Eprints.nottingham.ac.uk



Exploring the advantages of multiband fMRI with simultaneous EEG to investigate coupling between gamma frequency neural activity and the BOLD response in humans.Makoto Ujia, Ross Wilsona, Susan T. Francisb, Karen J. Mullingera,b*?, Stephen D. Mayhewa*a Centre for Human Brain Health (CHBH), School of Psychology, University of Birmingham, Birmingham, UKb Sir Peter Mansfield Imaging Centre (SPMIC), School of Physics and Astronomy, University of Nottingham, Nottingham, UK* these authors were equally responsible for leading this study? corresponding authorAbstractWe established an optimal combination of EEG recording during sparse multiband (MB) fMRI that preserves high resolution, whole brain fMRI coverage whilst enabling broad-band EEG recordings which are uncorrupted by MRI gradient artefacts (GAs). We firstly determined the safety of simultaneous EEG recording during MB fMRI. Application of MB factor=4 produced <1°C peak heating of electrode/hardware during 20-minutes of GE-EPI data acquisition. However, higher SAR sequences require specific safety testing, with greater heating observed using PCASL with MB factor=4. Heating was greatest in the electrocardiogram channel, likely due to it possessing longest lead length. We investigated the effect of MB factor on the temporal signal to noise ratio for a range of GE-EPI sequences (varying MB factor and temporal interval between slice acquisitions). We found that, for our experimental purpose, the optimal acquisition was achieved with MB factor=3, 3mm isotropic voxels and 33 slices providing whole head coverage. This sequence afforded a 2.25s duration quiet period (without GAs) in every 3s TR. Using this sequence we demonstrated the ability to record gamma frequency (55-80Hz) EEG oscillations, in response to right index finger abduction, that are usually obscured by GAs during continuous fMRI data acquisition. In this novel application of EEG-MB fMRI to a motor task we observed a positive correlation between gamma and BOLD responses in bilateral motor regions. These findings support and extend previous work regarding coupling between neural and haemodynamic measures of brain activity in humans and showcase the utility of EEG-MB fMRI for future investigations.KeywordsEEG-fMRIMultiband or multislice fMRIGamma-BOLD couplingGradient artefactsSafetyHeatingMotor gamma oscillationsIntroductionElectroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are two neuroimaging techniques that are often used to investigate human brain function. Simultaneous EEG-fMRI recordings provide a wide range of complimentary information and can be advantageous for improving our understanding of brain function, for example: through investigating the spatiotemporal dynamics of neural activity (for a review, see ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1523/JNEUROSCI.0447-12.2012", "ISBN" : "1529-2401 (Electronic) 0270-6474 (Linking)", "PMID" : "22553012", "abstract" : "The simultaneous recording and analysis of electroencephalography (EEG) and fMRI data in human systems, cognitive and clinical neurosciences is rapidly evolving and has received substantial attention. The significance of multimodal brain imaging is documented by a steadily increasing number of laboratories now using simultaneous EEG-fMRI aiming to achieve both high temporal and spatial resolution of human brain function. Due to recent developments in technical and algorithmic instrumentation, the rate-limiting step in multimodal studies has shifted from data acquisition to analytic aspects. Here, we introduce and compare different methods for data integration and identify the benefits that come with each approach, guiding the reader toward an understanding and informed selection of the integration approach most suitable for addressing a particular research question.", "author" : [ { "dropping-particle" : "", "family" : "Huster", "given" : "R J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Debener", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Eichele", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Herrmann", "given" : "C S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "id" : "ITEM-1", "issue" : "18", "issued" : { "date-parts" : [ [ "2012" ] ] }, "note" : "Huster, Rene J\nDebener, Stefan\nEichele, Tom\nHerrmann, Christoph S\neng\nIntroductory\nResearch Support, Non-U.S. Gov't\n2012/05/04 06:00\nJ Neurosci. 2012 May 2;32(18):6053-60. doi: 10.1523/JNEUROSCI.0447-12.2012.", "page" : "6053-6060", "title" : "Methods for simultaneous EEG-fMRI: an introductory review", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Huster et al., 2012)", "manualFormatting" : "Huster et al., 2012", "plainTextFormattedCitation" : "(Huster et al., 2012)", "previouslyFormattedCitation" : "(Huster et al., 2012)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Huster et al., 2012), or studying the underlying neurophysiological origins of the measured responses by comparing neural and haemodynamic signals e.g. ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1073/pnas.1221287110", "ISBN" : "1091-6490 (Electronic) 0027-8424 (Linking)", "PMID" : "23898206", "abstract" : "fMRI is the foremost technique for noninvasive measurement of human brain function. However, its utility is limited by an incomplete understanding of the relationship between neuronal activity and the hemodynamic response. Though the primary peak of the hemodynamic response is modulated by neuronal activity, the origin of the typically negative poststimulus signal is poorly understood and its amplitude assumed to covary with the primary response. We use simultaneous recordings of EEG with blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF) fMRI during unilateral median nerve stimulation to show that the poststimulus fMRI signal is neuronally modulated. We observe high spatial agreement between concurrent BOLD and CBF responses to median nerve stimulation, with primary signal increases in contralateral sensorimotor cortex and primary signal decreases in ipsilateral sensorimotor cortex. During the poststimulus period, the amplitude and directionality (positive/negative) of the BOLD signal in both contralateral and ipsilateral sensorimotor cortex depends on the poststimulus synchrony of 8-13 Hz EEG neuronal activity, which is often considered to reflect cortical inhibition, along with concordant changes in CBF and metabolism. Therefore we present conclusive evidence that the fMRI time course represents a hemodynamic signature of at least two distinct temporal phases of neuronal activity, substantially improving understanding of the origin of the BOLD response and increasing the potential measurements of brain function provided by fMRI. We suggest that the poststimulus EEG and fMRI responses may be required for the resetting of the entire sensory network to enable a return to resting-state activity levels.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mayhew", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bagshaw", "given" : "A P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Francis", "given" : "S T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "edition" : "2013/07/31", "id" : "ITEM-1", "issue" : "33", "issued" : { "date-parts" : [ [ "2013" ] ] }, "note" : "Mullinger, Karen J\nMayhew, Stephen D\nBagshaw, Andrew P\nBowtell, Richard\nFrancis, Susan T\nG0901321/Medical Research Council/United Kingdom\nProc Natl Acad Sci U S A. 2013 Aug 13;110(33):13636-41. doi: 10.1073/pnas.1221287110. Epub 2013 Jul 29.", "page" : "13636-13641", "title" : "Poststimulus undershoots in cerebral blood flow and BOLD fMRI responses are modulated by poststimulus neuronal activity", "type" : "article-journal", "volume" : "110" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2013)", "plainTextFormattedCitation" : "(Mullinger et al., 2013)", "previouslyFormattedCitation" : "(Mullinger et al., 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2013). The primary advantage of simultaneous EEG-fMRI acquisition over separate recordings is that it enables investigation of unpredictable or spontaneous brain activity, as well as studying the trial-by-trial covariation in brain processing as measured by the two techniques ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.20024", "ISBN" : "1065-9471 (Print)\\n1065-9471 (Linking)", "ISSN" : "10659471", "PMID" : "15195285", "abstract" : "Combined EEG-fMRI has recently been used to explore the BOLD responses\\nto interictal epileptiform discharges. This study examines whether\\nmisspecification of the form of the haemodynamic response function\\n(HRF) results in significant fMRI responses being missed in the statistical\\nanalysis. EEG-fMRI data from 31 patients with focal epilepsy were\\nanalysed with four HRFs peaking from 3 to 9 sec after each interictal\\nevent, in addition to a standard HRF that peaked after 5.4 sec. In\\nfour patients, fMRI responses were correlated with gadolinium-enhanced\\nMR angiograms and with EEG data from intracranial electrodes. In\\nan attempt to understand the absence of BOLD responses in a significant\\ngroup of patients, the degree of signal loss occurring as a result\\nof magnetic field inhomogeneities was compared with the detected\\nfMRI responses in ten patients with temporal lobe spikes. Using multiple\\nHRFs resulted in an increased percentage of data sets with significant\\nfMRI activations, from 45% when using the standard HRF alone, to\\n62.5%. The standard HRF was good at detecting positive BOLD responses,\\nbut less appropriate for negative BOLD responses, the majority of\\nwhich were more accurately modelled by an HRF that peaked later than\\nthe standard. Co-registration of statistical maps with gadolinium-enhanced\\nMRIs suggested that the detected fMRI responses were not in general\\nrelated to large veins. Signal loss in the temporal lobes seemed\\nto be an important factor in 7 of 12 patients who did not show fMRI\\nactivations with any of the HRFs.", "author" : [ { "dropping-particle" : "", "family" : "Bagshaw", "given" : "Andrew P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Aghakhani", "given" : "Yahya", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "B\u00e9nar", "given" : "Christian G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kobayashi", "given" : "Eliane", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawco", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dubeau", "given" : "Fran\u00e7ois", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pike", "given" : "G. 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Recent hardware and software developments have made it feasible to acquire EEG and fMRI data simultaneously. We emphasize the potential of simultaneous EEG and fMRI recordings to pursue new strategies in cognitive neuroimaging. Specifically, we propose that, by exploiting the combined spatiotemporal resolution of the methods, the integration of EEG and fMRI recordings on a single-trial level enables the rich temporal dynamics of information processing to be characterized within spatially well-defined neural networks. \u00a9 2006 Elsevier Ltd. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Debener", "given" : "Stefan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ullsperger", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Siegel", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Engel", "given" : "Andreas K.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Trends in Cognitive Sciences", "id" : "ITEM-3", "issue" : "12", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "558-563", "title" : "Single-trial EEG-fMRI reveals the dynamics of cognitive function", "type" : "article-journal", "volume" : "10" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1016/j.ijpsycho.2007.04.010", "ISBN" : "0167-8760 (Print)\\r0167-8760 (Linking)", "ISSN" : "01678760", "PMID" : "17688963", "abstract" : "Concurrent event-related EEG-fMRI recordings pick up volume-conducted and hemodynamically convoluted signals from latent neural sources that are spatially and temporally mixed across the brain, i.e. the observed data in both modalities represent multiple, simultaneously active, regionally overlapping neuronal mass responses. This mixing process decreases the sensitivity of voxel-by-voxel prediction of hemodynamic activation by the EEG when multiple sources contribute to either the predictor and/or the response variables. In order to address this problem, we used independent component analysis (ICA) to recover maps from the fMRI and timecourses from the EEG, and matched these components across the modalities by correlating their trial-to-trial modulation. The analysis was implemented as a group-level ICA that extracts a single set of components from the data and directly allows for population inferences about consistently expressed function-relevant spatiotemporal responses. We illustrate the utility of this method by extracting a previously undetected but relevant EEG-fMRI component from a concurrent auditory target detection experiment. \u00a9 2007 Elsevier B.V. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Eichele", "given" : "Tom", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Calhoun", "given" : "Vince D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Specht", "given" : "Karsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jongsma", "given" : "Marijtje L.A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Quiroga", "given" : "Rodrigo Quian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Nordby", "given" : "Helge", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hugdahl", "given" : "Kenneth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "International Journal of Psychophysiology", "id" : "ITEM-4", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "222-234", "title" : "Unmixing concurrent EEG-fMRI with parallel independent component analysis", "type" : "article-journal", "volume" : "67" }, "uris" : [ "" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.1097/01.wnr.0000047685.08940.d0", "abstract" : "The alpha rhythm in the EEG is 8-12 Hz activity present when a subject is awake with eyes closed. In this study, we used simultaneous EEG and fMRI to make maps of regions whose MRI signal changed reliably with modulation in posterior alpha activity. We scanned 11 subjects as they rested with eyes closed. We found that increased alpha power was correlated with decreased MRI signal in multiple regions of occipital, superior temporal, inferior frontal, and cingulate cortex, and with increased signal in the thalamus and insula. These results are consistent with animal experiments and point to the alpha rhythm as an index of cortical inactivity that may be generated in part by the thalamus. These results also may have important implications for interpretation of resting baseline in fMRI studies.", "author" : [ { "dropping-particle" : "", "family" : "Goldman", "given" : "Robin I", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stern", "given" : "John M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Engel Jerome", "given" : "Jr", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cohen", "given" : "Mark S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroreport", "id" : "ITEM-5", "issue" : "18", "issued" : { "date-parts" : [ [ "2002" ] ] }, "page" : "2487-2492", "title" : "Simultaneous EEG and fMRI of the alpha rhythm", "type" : "article-journal", "volume" : "13" }, "uris" : [ "" ] }, { "id" : "ITEM-6", "itemData" : { "DOI" : "10.1002/hbm.20428", "ISBN" : "1097-0193 (Electronic)\\r1065-9471 (Linking)", "ISSN" : "10659471", "PMID" : "17598166", "abstract" : "Recent blood oxygenation level dependent functional MRI (BOLD fMRI) studies of the human brain have shown that in the absence of external stimuli, activity persists in the form of distinct patterns of temporally correlated signal fluctuations. In this work, we investigated the spontaneous BOLD signal fluctuations during states of reduced consciousness such as drowsiness and sleep. For this purpose, we performed BOLD fMRI on normal subjects during varying levels of consciousness, from resting wakefulness to light (non-slow wave) sleep. Depth of sleep was determined based on concurrently acquired EEG data. During light sleep, significant increases in the fluctuation level of the BOLD signal were observed in several cortical areas, among which visual cortex was the most significant. Correlations among brain regions involved with the default-mode network persisted during light sleep. These results suggest that activity in areas such as the default-mode network and primary sensory cortex, as measured from BOLD fMRI fluctuations, does not require a level of consciousness typical of wakefulness.", "author" : [ { "dropping-particle" : "", "family" : "Horovitz", "given" : "Silvina G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fukunaga", "given" : "Masaki", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Zwart", "given" : "Jacco A.", "non-dropping-particle" : "De", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gelderen", "given" : "Peter", "non-dropping-particle" : "Van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fulton", "given" : "Susan C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Balkin", "given" : "Thomas J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Duyn", "given" : "Jeff H.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Human Brain Mapping", "id" : "ITEM-6", "issue" : "6", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "671-682", "title" : "Low frequency BOLD fluctuations during resting wakefulness and light sleep: A simultaneous EEG-fMRI study", "type" : "article-journal", "volume" : "29" }, "uris" : [ "" ] }, { "id" : "ITEM-7", "itemData" : { "DOI" : "10.1016/j.neuroimage.2013.02.070", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "23507378", "abstract" : "The human brain is continually, dynamically active and spontaneous fluctuations in this activity play a functional role in affecting both behavioural and neuronal responses. However, the mechanisms through which this occurs remain poorly understood. Simultaneous EEG-fMRI is a promising technique to study how spontaneous activity modulates the brain's response to stimulation, as temporal indices of ongoing cortical excitability can be integrated with spatially localised evoked responses. Here we demonstrate an interaction between the ongoing power of the electrophysiological alpha oscillation and the magnitude of both positive (PBR) and negative (NBR) fMRI responses to two contrasts of visual checkerboard reversal. Furthermore, the amplitude of pre-stimulus EEG alpha-power significantly modulated the amplitude and shape of subsequent PBR and NBR to the visual stimulus. A nonlinear reduction of visual PBR and an enhancement of auditory NBR and default-mode network NBR were observed in trials preceded by high alpha-power. These modulated areas formed a functionally connected network during a separate resting-state recording. Our findings suggest that the \"baseline\" state of the brain exhibits considerable trial-to-trial variability which arises from fluctuations in the balance of cortical inhibition/excitation that are represented by respective increases/decreases in the power of the EEG alpha oscillation. The consequence of this spontaneous electrophysiological variability is modulated amplitudes of both PBR and NBR to stimulation. Fluctuations in alpha-power may subserve a functional relationship in the visual-auditory network, acting as mediator for both short and long-range cortical inhibition, the strength of which is represented in part by NBR.", "author" : [ { "dropping-particle" : "", "family" : "Mayhew", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ostwald", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Porcaro", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bagshaw", "given" : "A P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2013/03/20", "id" : "ITEM-7", "issued" : { "date-parts" : [ [ "2013" ] ] }, "note" : "Mayhew, Stephen D\nOstwald, Dirk\nPorcaro, Camillo\nBagshaw, Andrew P\nNeuroimage. 2013 Aug 1;76:362-72. doi: 10.1016/j.neuroimage.2013.02.070. Epub 2013 Mar 15.", "page" : "362-372", "title" : "Spontaneous EEG alpha oscillation interacts with positive and negative BOLD responses in the visual-auditory cortices and default-mode network", "type" : "article-journal", "volume" : "76" }, "uris" : [ "" ] }, { "id" : "ITEM-8", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.12.051", "abstract" : "Pain is a complex experience with sensory, emotional and cognitive aspects. The cortical representation of pain - the pain matrix - consists of a network of regions including the primary (S1) and secondary (S2) sensory cortex, insula, and anterior cingulate cortex (ACC). These structures interact with brain regions such as the prefrontal cortex and the amygdalae. Simultaneous EEG/fMRI (electroencephalography/functional magnetic resonance imaging) has recently been introduced as a method to study the spatiotemporal characteristics of cognitive processes with high spatial and high temporal resolution at the same time. The present study was conducted to clarify if single trial EEG-informed BOLD modeling supports the definition of functional compartments within the pain matrix and interconnected regions. Twenty healthy subjects received painful laser stimulation while EEG and the fMRI blood oxygen level dependent (BOLD) signal were recorded simultaneously. While the laser-evoked N2 potential provided no additional information for BOLD modeling, the regressor obtained from the single trial laser-evoked P2 potential explained additional variance in a network of cortical and subcortical structures that largely overlapped with the pain matrix. This modeling strategy yielded pronounced activation in the ACC, right amygdala and thalamus. Our results suggest that laser-evoked potential (LEP) informed fMRI can be used to visualize BOLD activation in the pain matrix with an emphasis on functional compartments (as defined by the temporal dynamics of the LEP) such as the medial pain system. Furthermore, our findings suggest a concerted effort of the ACC and the amygdala in the cognitive-emotional evaluation of pain.", "author" : [ { "dropping-particle" : "", "family" : "Mobascher", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brinkmeyer", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Warbrick", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Musso", "given" : "F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wittsack", "given" : "H J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Saleh", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schnitzler", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Winterer", "given" : "G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-8", "issue" : "3", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "917-926", "title" : "Laser-evoked potential P2 single-trial amplitudes covary with the fMRI BOLD response in the medial pain system and interconnected subcortical structures", "type" : "article-journal", "volume" : "45" }, "uris" : [ "" ] }, { "id" : "ITEM-9", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mayhew", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bagshaw", "given" : "A P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Francis", "given" : "S T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-9", "issued" : { "date-parts" : [ [ "2014" ] ] }, "page" : "263-274", "title" : "Evidence that the negative BOLD response is neuronal in origin: a simultaneous EEG-BOLD-CBF study in humans", "type" : "article-journal", "volume" : "94" }, "uris" : [ "" ] }, { "id" : "ITEM-10", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.11.014", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19110062", "abstract" : "Different EEG-vigilance stages from full alertness to sleep onset can be separated during rest. Also fMRI research recently focused on the resting condition and identified several resting state networks. In order to deepen the understanding of different levels of global brain function from relaxed wakefulness to sleep onset the association between EEG-vigilance stages and BOLD signals was analysed. EEG-vigilance stages were attributed to consecutive 3-sec-EEG-segments by an algorithm using topographic and spectral information. Results of the classification were validated by analysing the heart rates during the different brain states. Vigilance stages served as regressors for the analysis of the simultaneously acquired fMRI data. Additionally resting state networks were derived from the fMRI data using independent component analysis (ICA). Also vigilance associated brain activity revealed by EEG-based standardized low resolution tomography (sLORETA) was compared to the results of the fMRI analysis. Results showed increased BOLD signal in the occipital cortex, the anterior cingulate cortex, the frontal cortex, the parietal cortices and the temporal cortices and decreasing BOLD signals in the thalamus and the frontal cortex for declining vigilance stages (A2, A3, B1, B2/B3) in comparison to the high vigilance stage A1. Resting state networks revealed a spatial overlap with the vigilance stage associated BOLD maps in conjunction analyses. sLORETA showed increased neuroelectric alpha activity at the occipital cortex comparable to occipital BOLD signal decreases when comparing stage A with stage B. Different EEG-vigilance stages during rest are associated with pronounced differences of BOLD signals in several brain areas which partly correspond to the resting state networks. For cognitive fMRI-research it therefore seems important to pay attention to vigilance switches in order to separate vigilance associated BOLD signal changes from those specifically related to cognition.", "author" : [ { "dropping-particle" : "", "family" : "Olbrich", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mulert", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Trenner", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2008/12/27", "id" : "ITEM-10", "issue" : "2", "issued" : { "date-parts" : [ [ "2009" ] ] }, "note" : "Olbrich, Sebastian\nMulert, Christoph\nKarch, Susanne\nTrenner, Maja\nLeicht, Gregor\nPogarell, Oliver\nHegerl, Ulrich\nNeuroimage. 2009 Apr 1;45(2):319-32. doi: 10.1016/j.neuroimage.2008.11.014. Epub 2008 Nov 28.", "page" : "319-332", "title" : "EEG-vigilance and BOLD effect during simultaneous EEG/fMRI measurement", "type" : "article-journal", "volume" : "45" }, "uris" : [ "" ] }, { "id" : "ITEM-11", "itemData" : { "DOI" : "30/49/16709 [pii] 10.1523/JNEUROSCI.3949-09.2010", "ISBN" : "1529-2401 (Electronic) 0270-6474 (Linking)", "PMID" : "21148010", "abstract" : "Prior knowledge of the probabilities concerning decision alternatives facilitates the selection of more likely alternatives to the disadvantage of others. The neural basis of prior probability (PP) integration into the decision-making process and associated preparatory processes is, however, still essentially unknown. Furthermore, trial-to-trial fluctuations in PP processing have not been considered thus far. In a previous study, we found that the amplitude of the contingent negative variation (CNV) in a precueing task is sensitive to PP information (Scheibe et al., 2009). We investigated brain regions with a parametric relationship between neural activity and PP and those regions involved in PP processing on a trial-to-trial basis in simultaneously recorded electroencephalographic (EEG) and functional magnetic resonance imaging (fMRI) data. Conventional fMRI analysis focusing on the information content of the probability precue revealed increasing activation of the posterior medial frontal cortex with increasing PP, supporting its putative role in updating action values. EEG-informed fMRI analysis relating single-trial CNV amplitudes to the hemodynamic signal addressed trial-to-trial fluctuations in PP processing. We identified a set of regions mainly consisting of frontal, parietal, and striatal regions that represents unspecific response preparation on a trial-to-trial basis. A subset of these regions, namely, the dorsolateral prefrontal cortex, the inferior frontal gyrus, and the inferior parietal lobule, showed activations that exclusively represented the contributions of PP to the trial-to-trial fluctuations of the CNV.", "author" : [ { "dropping-particle" : "", "family" : "Scheibe", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ullsperger", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sommer", "given" : "W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Heekeren", "given" : "H R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "edition" : "2010/12/15", "id" : "ITEM-11", "issue" : "49", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Scheibe, Christina\nUllsperger, Markus\nSommer, Werner\nHeekeren, Hauke R\nResearch Support, Non-U.S. Gov't\nUnited States\nThe Journal of neuroscience : the official journal of the Society for Neuroscience\nJ Neurosci. 2010 Dec 8;30(49):16709-17.", "page" : "16709-16717", "title" : "Effects of parametrical and trial-to-trial variation in prior probability processing revealed by simultaneous electroencephalogram/functional magnetic resonance imaging", "type" : "article-journal", "volume" : "30" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Bagshaw et al., 2004; Becker et al., 2011; Debener et al., 2006; Eichele et al., 2008; Goldman et al., 2002; Horovitz et al., 2008; Mayhew et al., 2013; Mobascher et al., 2009; Mullinger et al., 2014; Olbrich et al., 2009; Scheibe et al., 2010)", "plainTextFormattedCitation" : "(Bagshaw et al., 2004; Becker et al., 2011; Debener et al., 2006; Eichele et al., 2008; Goldman et al., 2002; Horovitz et al., 2008; Mayhew et al., 2013; Mobascher et al., 2009; Mullinger et al., 2014; Olbrich et al., 2009; Scheibe et al., 2010)", "previouslyFormattedCitation" : "(Bagshaw et al., 2004; Becker et al., 2011; Debener et al., 2006; Eichele et al., 2008; Goldman et al., 2002; Horovitz et al., 2008; Mayhew et al., 2013; Mobascher et al., 2009; Mullinger et al., 2014; Olbrich et al., 2009; Scheibe et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Bagshaw et al., 2004; Becker et al., 2011; Debener et al., 2006; Eichele et al., 2008; Goldman et al., 2002; Horovitz et al., 2008; Mayhew et al., 2013; Mobascher et al., 2009; Mullinger et al., 2014; Olbrich et al., 2009; Scheibe et al., 2010). Thus simultaneous recordings enable spatial localisation of temporally dynamic response features. EEG-fMRI analysis has provided many novel insights into brain function. For example, such analyses have demonstrated specific BOLD correlates of: distinct neurophysiological components including the auditory oddball ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.20289", "ISBN" : "1065-9471 (Print)\\r1065-9471 (Linking)", "ISSN" : "10659471", "PMID" : "17295312", "abstract" : "There has recently been a growing interest in the use of simultaneous electroencephalography (EEG) and functional MRI (fMRI) for evoked activity in cognitive paradigms, thereby obtaining functional datasets with both high spatial and temporal resolution. The simultaneous recording permits obtaining event-related potentials (ERPs) and MR images in the same environment, conditions of stimulation, and subject state; it also enables tracing the joint fluctuations of EEG and fMRI signals. The goal of this study was to investigate the possibility of tracking the trial-to-trial changes in event-related EEG activity, and of using this information as a parameter in fMRI analysis. We used an auditory oddball paradigm and obtained single-trial amplitude and latency features from the EEG acquired during fMRI scanning. The single-trial P300 latency presented significant correlation with parameters external to the EEG (target-to-target interval and reaction time). Moreover, we obtained significant fMRI activations for the modulation by P300 amplitude and latency, both at the single-subject and at the group level. Our results indicate that, in line with other studies, the EEG can bring a new dimension to the field of fMRI analysis by providing fine temporal information on the fluctuations in brain activity.", "author" : [ { "dropping-particle" : "", "family" : "B\u00e9nar", "given" : "Christian G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sch\u00f6n", "given" : "Daniele", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grimault", "given" : "Stephan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Nazarian", "given" : "Bruno", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Burle", "given" : "Boris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Roth", "given" : "Muriel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Badier", "given" : "Jean Michel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Marquis", "given" : "Patrick", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Liegeois-Chauvel", "given" : "Catherine", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Anton", "given" : "Jean Luc", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Human Brain Mapping", "id" : "ITEM-1", "issue" : "7", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "602-613", "title" : "Single-trial analysis of oddball event-related potentials in simultaneous EEG-fMRI", "type" : "article-journal", "volume" : "28" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1073/pnas.0505508102", "abstract" : "The brain acts as an integrated information processing system, which methods in cognitive neuroscience have so far depicted in a fragmented fashion. Here, we propose a simple and robust way to integrate functional MRI (fMRI) with single trial event-related potentials (ERP) to provide a more complete spatiotemporal characterization of evoked responses in the human brain. The idea behind the approach is to find brain regions whose fMRI responses can be predicted by paradigm-induced amplitude modulations of simultaneously acquired single trial ERPs. The method was used to study a variant of a two-stimulus auditory target detection (odd-ball) paradigm that manipulated predictability through alternations of stimulus sequences with random or regular target-to-target intervals. In addition to electrophysiologic and hemodynamic evoked responses to auditory targets per se, single-trial modulations were expressed during the latencies of the P2 (170-ms), N2 (200-ms), and P3 (320-ms) components and predicted spatially separated fMRI activation patterns. These spatiotemporal matches, i.e., the prediction of hemodynamic activation by time-variant information from single trial ERPs, permit inferences about regional responses using fMRI with the temporal resolution provided by electrophysiology.", "author" : [ { "dropping-particle" : "", "family" : "Eichele", "given" : "Tom", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Specht", "given" : "Karsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jongsma", "given" : "Marijtje L A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Quiroga", "given" : "Rodrigo Quian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Nordby", "given" : "Helge", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hugdahl", "given" : "Kenneth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "id" : "ITEM-2", "issue" : "49", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "17798-17803", "title" : "Assessing the spatiotemporal evolution of neuronal activation with single-trial event-related potentials and functional MRI", "type" : "article-journal", "volume" : "102" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(B\u00e9nar et al., 2007; Eichele et al., 2005)", "plainTextFormattedCitation" : "(B\u00e9nar et al., 2007; Eichele et al., 2005)", "previouslyFormattedCitation" : "(B\u00e9nar et al., 2007; Eichele et al., 2005)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Bénar et al., 2007; Eichele et al., 2005) and the error-related negativity ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1523/JNEUROSCI.3286-05.2005", "abstract" : "Goal-directed behavior requires the continuous monitoring and dynamic adjustment of ongoing actions. Here, we report a direct coupling between the event-related electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and behavioral measures of performance monitoring in humans. By applying independent component analysis to EEG signals recorded simultaneously with fMRI, we found the single-trial error-related negativity of the EEG to be systematically related to behavior in the subsequent trial, thereby reflecting immediate behavioral adjustments of a cognitive performance monitoring system. Moreover, this trial-by-trial EEG measure of performance monitoring predicted the fMRI activity in the rostral cingulate zone, a brain region thought to play a key role in processing of response errors. We conclude that investigations of the dynamic coupling between EEG and fMRI provide a powerful approach for the study of higher order brain functions.", "author" : [ { "dropping-particle" : "", "family" : "Debener", "given" : "Stefan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ullsperger", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Siegel", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fiehler", "given" : "Katja", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cramon", "given" : "D Yves", "non-dropping-particle" : "von", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Engel", "given" : "Andreas K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "id" : "ITEM-1", "issue" : "50", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "11730-11737", "title" : "Trial-by-trial coupling of concurrent electroencephalogram and functional magnetic resonance imaging identifies the dynamics of performance monitoring", "type" : "article-journal", "volume" : "25" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Debener et al., 2005)", "plainTextFormattedCitation" : "(Debener et al., 2005)", "previouslyFormattedCitation" : "(Debener et al., 2005)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Debener et al., 2005); as well as specific neural activity in specific frequency bands ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1097/01.wnr.0000047685.08940.d0", "abstract" : "The alpha rhythm in the EEG is 8-12 Hz activity present when a subject is awake with eyes closed. In this study, we used simultaneous EEG and fMRI to make maps of regions whose MRI signal changed reliably with modulation in posterior alpha activity. We scanned 11 subjects as they rested with eyes closed. We found that increased alpha power was correlated with decreased MRI signal in multiple regions of occipital, superior temporal, inferior frontal, and cingulate cortex, and with increased signal in the thalamus and insula. These results are consistent with animal experiments and point to the alpha rhythm as an index of cortical inactivity that may be generated in part by the thalamus. These results also may have important implications for interpretation of resting baseline in fMRI studies.", "author" : [ { "dropping-particle" : "", "family" : "Goldman", "given" : "Robin I", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stern", "given" : "John M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Engel Jerome", "given" : "Jr", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cohen", "given" : "Mark S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroreport", "id" : "ITEM-1", "issue" : "18", "issued" : { "date-parts" : [ [ "2002" ] ] }, "page" : "2487-2492", "title" : "Simultaneous EEG and fMRI of the alpha rhythm", "type" : "article-journal", "volume" : "13" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "abstract" : "Electroencephalography-correlated functional magnetic resonance imaging (EEG/fMRI) can be used to identify blood oxygen level-dependent (BOLD) signal changes associated with both physiological and pathological EEG events. Here, we implemented continuous and simultaneous EEG/fMRI to identify BOLD signal changes related to spontaneous power fluctuations in the alpha rhythm (8-12 Hz), the dominant EEG pattern during relaxed wakefulness. Thirty-two channels of EEG were recorded in 10 subjects during eyes-closed rest inside a 1.5-T magnet resonance (MR) scanner using an MR-compatible EEG recording system. Functional scanning by echoplanar imaging covered almost the entire cerebrum every 4 s. Off-line MRI artifact subtraction software was applied to obtain continuous EEG data during fMRI acquisition. The average alpha power over 1-s epochs was derived at several electrode positions using a Fast Fourier Transform. The power time course was then convolved with a canonical hemodynamic response function, down-sampled, and used for statistical parametric mapping of associated signal changes in the image time series. At all electrode positions studied, a strong negative correlation of parietal and frontal cortical activity with alpha power was found. Conversely, only sparse and nonsystematic positive correlation was detected. The relevance of these findings is discussed in view of the current theories on the generation and significance of the alpha rhythm and the related functional neuroimaging findings.", "author" : [ { "dropping-particle" : "", "family" : "Laufs", "given" : "H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kleinschmidt", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Beyerle", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Eger", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Salek-Haddadi", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Preibisch", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Krakow", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-2", "issue" : "4", "issued" : { "date-parts" : [ [ "2003" ] ] }, "page" : "1463-1476", "title" : "EEG-correlated fMRI of human alpha activity", "type" : "article-journal", "volume" : "19" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Goldman et al., 2002; Laufs et al., 2003)", "plainTextFormattedCitation" : "(Goldman et al., 2002; Laufs et al., 2003)", "previouslyFormattedCitation" : "(Goldman et al., 2002; Laufs et al., 2003)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Goldman et al., 2002; Laufs et al., 2003). These studies have shown that simultaneous EEG-fMRI can provide greater speci?city regarding the spatial arrangement ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.03.062", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19345734", "abstract" : "The auditory oddball task is a well-studied stimulus paradigm used to investigate the neural correlates of simple target detection. It elicits several classic event-related potentials (ERPs), the most prominent being the P300 which is seen as a neural correlate of subjects' detection of rare (target) stimuli. Though trial-averaging is typically used to identify and characterize such ERPs, their latency and amplitude can vary on a trial-to-trial basis reflecting variability in the underlying neural information processing. Here we simultaneously recorded EEG and fMRI during an auditory oddball task and identified cortical areas correlated with the trial-to-trial variability of task-discriminating EEG components. Unique to our approach is a linear multivariate method for identifying task-discriminating components within specific stimulus- or response-locked time windows. We find fMRI activations indicative of distinct processes that contribute to the single-trial variability during target detection. These regions are different from those found using standard, including trial-averaged, regressors. Of particular note is the strong activation of the lateral occipital complex (LOC). The LOC was not seen when using traditional event-related regressors. Though LOC is typically associated with visual/spatial attention, its activation in an auditory oddball task, where attention can wax and wane from trial to trial, indicates that it may be part of a more general attention network involved in allocating resources for target detection and decision making. Our results show that trial-to-trial variability in EEG components, acquired simultaneously with fMRI, can yield task-relevant BOLD activations that are otherwise unobservable using traditional fMRI analysis.", "author" : [ { "dropping-particle" : "", "family" : "Goldman", "given" : "R I", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wei", "given" : "C Y", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Philiastides", "given" : "M G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gerson", "given" : "A D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Friedman", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brown", "given" : "T R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sajda", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2009/04/07", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2009" ] ] }, "note" : "Goldman, Robin I\nWei, Cheng-Yu\nPhiliastides, Marios G\nGerson, Adam D\nFriedman, David\nBrown, Truman R\nSajda, Paul\nAG005213/AG/NIA NIH HHS/\nEB004730/EB/NIBIB NIH HHS/\nHD14959/HD/NICHD NIH HHS/\nR01 MH085092/MH/NIMH NIH HHS/\nR33 EB004730-04/EB/NIBIB NIH HHS/\nNeuroimage. 2009 Aug 1;47(1):136-47. doi: 10.1016/j.neuroimage.2009.03.062. Epub 2009 Apr 2.", "page" : "136-147", "title" : "Single-trial discrimination for integrating simultaneous EEG and fMRI: identifying cortical areas contributing to trial-to-trial variability in the auditory oddball task", "type" : "article-journal", "volume" : "47" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2010.09.041", "abstract" : "Simultaneous EEG-fMRI measurements can combine the high spatial resolution of fMRI with the high temporal resolution of EEG. Therefore, we applied this approach to the study of peripheral vision. More specifically, we presented visual field quadrant fragments of checkerboards and a full central checkerboard in a simple detection task. A technique called \"integration-by-prediction\" was used to integrate EEG and fMRI data. In particular, we used vectors of single-trial ERP amplitude differences between left and right occipital electrodes as regressors in an ERP-informed fMRI analysis. The amplitude differences for the regressors were measured at the latencies of the visual P1 and N1 components. Our results indicated that the traditional event-related fMRI analysis revealed mostly activations in the vicinity of the primary visual cortex and in the ventral visual stream, while both P1 and N1 regressors revealed activation of areas in the temporo-parietal junction. We conclude that simultaneous EEG-fMRI in a spatial detection task can separate visual processing at 100-200 ms from stimulus onset from the rest of the information processing in the brain.", "author" : [ { "dropping-particle" : "", "family" : "Novitskiy", "given" : "N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ramautar", "given" : "J R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vanderperren", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vos", "given" : "M", "non-dropping-particle" : "De", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mennes", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mijovic", "given" : "B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vanrumste", "given" : "B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stiers", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bergh", "given" : "B", "non-dropping-particle" : "Van den", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lagae", "given" : "L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sunaert", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Huffel", "given" : "S", "non-dropping-particle" : "Van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wagemans", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-2", "issue" : "2", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "824-835", "title" : "The BOLD correlates of the visual P1 and N1 in single-trial analysis of simultaneous EEG-fMRI recordings during a spatial detection task", "type" : "article-journal", "volume" : "54" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Goldman et al., 2009; Novitskiy et al., 2011)", "plainTextFormattedCitation" : "(Goldman et al., 2009; Novitskiy et al., 2011)", "previouslyFormattedCitation" : "(Goldman et al., 2009; Novitskiy et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Goldman et al., 2009; Novitskiy et al., 2011) or the temporal sequence ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1073/pnas.0505508102", "abstract" : "The brain acts as an integrated information processing system, which methods in cognitive neuroscience have so far depicted in a fragmented fashion. Here, we propose a simple and robust way to integrate functional MRI (fMRI) with single trial event-related potentials (ERP) to provide a more complete spatiotemporal characterization of evoked responses in the human brain. The idea behind the approach is to find brain regions whose fMRI responses can be predicted by paradigm-induced amplitude modulations of simultaneously acquired single trial ERPs. The method was used to study a variant of a two-stimulus auditory target detection (odd-ball) paradigm that manipulated predictability through alternations of stimulus sequences with random or regular target-to-target intervals. In addition to electrophysiologic and hemodynamic evoked responses to auditory targets per se, single-trial modulations were expressed during the latencies of the P2 (170-ms), N2 (200-ms), and P3 (320-ms) components and predicted spatially separated fMRI activation patterns. These spatiotemporal matches, i.e., the prediction of hemodynamic activation by time-variant information from single trial ERPs, permit inferences about regional responses using fMRI with the temporal resolution provided by electrophysiology.", "author" : [ { "dropping-particle" : "", "family" : "Eichele", "given" : "Tom", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Specht", "given" : "Karsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jongsma", "given" : "Marijtje L A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Quiroga", "given" : "Rodrigo Quian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Nordby", "given" : "Helge", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hugdahl", "given" : "Kenneth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "id" : "ITEM-1", "issue" : "49", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "17798-17803", "title" : "Assessing the spatiotemporal evolution of neuronal activation with single-trial event-related potentials and functional MRI", "type" : "article-journal", "volume" : "102" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1523/JNEUROSCI.2033-11.2012", "ISBN" : "1529-2401 (Electronic)\\r0270-6474 (Linking)", "ISSN" : "1529-2401", "PMID" : "22262876", "abstract" : "Learning is known to facilitate our ability to detect targets in clutter and optimize brain processes for successful visual recognition. Previous brain-imaging studies have focused on identifying spatial patterns (i.e., brain areas) that change with learning, implicating occipitotemporal and frontoparietal areas. However, little is known about the interactions within this network that mediate learning-dependent improvement in complex perceptual tasks (i.e., discrimination of visual forms in clutter). Here we take advantage of the complementary high spatial and temporal resolution of simultaneous EEG-fMRI to identify the learning-dependent changes in spatiotemporal brain patterns that mediate enhanced behavioral sensitivity in the discrimination of global forms after training. We measured the observers' choices when discriminating between concentric and radial patterns presented in noise before and after training. Similarly, we measured the choices of a pattern classifier when predicting each stimulus from EEG-fMRI signals. By comparing the performance of human observers and classifiers, we demonstrated that learning alters sensitivity to visual forms and EEG-fMRI activation patterns related to distinct visual recognition processes. In particular, behavioral improvement after training was associated with changes in (1) early processes involved in the integration of global forms in higher occipitotemporal and parietal areas, and (2) later processes related to categorical judgments in frontal circuits. Thus, our findings provide evidence that learning acts on distinct visual recognition processes and shapes feedforward interactions across brain areas to support performance in complex perceptual tasks.", "author" : [ { "dropping-particle" : "", "family" : "Mayhew", "given" : "Stephen D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Li", "given" : "Sheng", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kourtzi", "given" : "Zoe", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "The Journal of neuroscience : the official journal of the Society for Neuroscience", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "775-86", "title" : "Learning acts on distinct processes for visual form perception in the human brain.", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Eichele et al., 2005; Mayhew et al., 2012)", "plainTextFormattedCitation" : "(Eichele et al., 2005; Mayhew et al., 2012)", "previouslyFormattedCitation" : "(Eichele et al., 2005; Mayhew et al., 2012)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Eichele et al., 2005; Mayhew et al., 2012) of responsive brain areas, compared to that revealed by a standard analysis of data from a single neuroimaging modality.Recently, neuronal activity in the gamma frequency band, which is typically defined as between approximately 30-100Hz, has attracted much interest because gamma synchronization has been linked with a range of cognitive and sensory functions ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1126/science.1138071", "ISBN" : "0036-8075", "ISSN" : "0036-8075", "PMID" : "17395832", "abstract" : "Attention can be focused volitionally by \"top-down\" signals derived from task demands and automatically by \"bottom-up\" signals from salient stimuli. The frontal and parietal cortices are involved, but their neural activity has not been directly compared. Therefore, we recorded from them simultaneously in monkeys. Prefrontal neurons reflected the target location first during top-down attention, whereas parietal neurons signaled it earlier during bottom-up attention. Synchrony between frontal and parietal areas was stronger in lower frequencies during top-down attention and in higher frequencies during bottom-up attention. This result indicates that top-down and bottom-up signals arise from the frontal and sensory cortex, respectively, and different modes of attention may emphasize synchrony at different frequencies.", "author" : [ { "dropping-particle" : "", "family" : "Buschman", "given" : "Timothy J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "Earl K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science (New York, N.Y.)", "id" : "ITEM-1", "issue" : "5820", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "1860-1862", "title" : "Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices.", "type" : "article-journal", "volume" : "315" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1126/science.1099745", "ISBN" : "1095-9203 (Electronic) 0036-8075 (Linking)", "ISSN" : "0036-8075", "PMID" : "15218136", "author" : [ { "dropping-particle" : "", "family" : "Buzsaki", "given" : "Gyoergy", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Draguhn", "given" : "Andreas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science", "id" : "ITEM-2", "issue" : "June", "issued" : { "date-parts" : [ [ "2004" ] ] }, "page" : "1926-1929", "title" : "Neuronal Oscillations in Cortical Networks", "type" : "article-journal", "volume" : "304" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1038/nature08573", "ISBN" : "0028-0836", "ISSN" : "1476-4687", "PMID" : "19924214", "abstract" : "Gamma oscillations are thought to transiently link distributed cell assemblies that are processing related information, a function that is probably important for network processes such as perception, attentional selection and memory. This 'binding' mechanism requires that spatially distributed cells fire together with millisecond range precision; however, it is not clear how such coordinated timing is achieved given that the frequency of gamma oscillations varies substantially across space and time, from approximately 25 to almost 150 Hz. Here we show that gamma oscillations in the CA1 area of the hippocampus split into distinct fast and slow frequency components that differentially couple CA1 to inputs from the medial entorhinal cortex, an area that provides information about the animal's current position, and CA3, a hippocampal subfield essential for storage of such information. Fast gamma oscillations in CA1 were synchronized with fast gamma in medial entorhinal cortex, and slow gamma oscillations in CA1 were coherent with slow gamma in CA3. Significant proportions of cells in medial entorhinal cortex and CA3 were phase-locked to fast and slow CA1 gamma waves, respectively. The two types of gamma occurred at different phases of the CA1 theta rhythm and mostly on different theta cycles. These results point to routeing of information as a possible function of gamma frequency variations in the brain and provide a mechanism for temporal segregation of potentially interfering information from different sources.", "author" : [ { "dropping-particle" : "", "family" : "Colgin", "given" : "Laura Lee", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Denninger", "given" : "Tobias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fyhn", "given" : "Marianne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hafting", "given" : "Torkel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bonnevie", "given" : "Tora", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jensen", "given" : "Ole", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moser", "given" : "May-Britt", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moser", "given" : "Edvard I", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature", "id" : "ITEM-3", "issue" : "7271", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "353-357", "publisher" : "Nature Publishing Group", "title" : "Frequency of gamma oscillations routes flow of information in the hippocampus.", "type" : "article-journal", "volume" : "462" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1146/annurev.neuro.051508.135603", "ISBN" : "1545-4126 (Electronic) 0147-006X (Linking)", "PMID" : "19400723", "abstract" : "Neuronal gamma-band synchronization is found in many cortical areas, is induced by different stimuli or tasks, and is related to several cognitive capacities. Thus, it appears as if many different gamma-band synchronization phenomena subserve many different functions. I argue that gamma-band synchronization is a fundamental process that subserves an elemental operation of cortical computation. Cortical computation unfolds in the interplay between neuronal dynamics and structural neuronal connectivity. A core motif of neuronal connectivity is convergence, which brings about both selectivity and invariance of neuronal responses. However, those core functions can be achieved simultaneously only if converging neuronal inputs are functionally segmented and if only one segment is selected at a time. This segmentation and selection can be elegantly achieved if structural connectivity interacts with neuronal synchronization. I propose that this process is at least one of the fundamental functions of gamma-band synchronization, which then subserves numerous higher cognitive functions.", "author" : [ { "dropping-particle" : "", "family" : "Fries", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Annu Rev Neurosci", "edition" : "2009/04/30", "id" : "ITEM-4", "issued" : { "date-parts" : [ [ "2009" ] ] }, "note" : "Fries, Pascal\nAnnu Rev Neurosci. 2009;32:209-24. doi: 10.1146/annurev.neuro.051508.135603.", "page" : "209-224", "title" : "Neuronal gamma-band synchronization as a fundamental process in cortical computation", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.1146/annurev.neuro.18.1.555", "ISBN" : "0147-006X (Print) 0147-006x", "ISSN" : "0147006X", "PMID" : "7605074", "abstract" : "The mammalian visual system is endowed with a nearly infinite capacity for the recognition of patterns and objects. To have acquired this capability the visual system must have solved what is a fundamentally combinatorial prob lem. Any given image consists of a collection ... \\n", "author" : [ { "dropping-particle" : "", "family" : "Singer", "given" : "Wolf", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gray", "given" : "Charles M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Annual Review of Neuroscience", "id" : "ITEM-5", "issue" : "1", "issued" : { "date-parts" : [ [ "1995" ] ] }, "page" : "555-586", "title" : "Visual Feature Integration and the Temporal Correlation Hypothesis", "type" : "article-journal", "volume" : "18" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Buschman and Miller, 2007; Buzsaki and Draguhn, 2004; Colgin et al., 2009; Fries, 2009; Singer and Gray, 1995)", "plainTextFormattedCitation" : "(Buschman and Miller, 2007; Buzsaki and Draguhn, 2004; Colgin et al., 2009; Fries, 2009; Singer and Gray, 1995)", "previouslyFormattedCitation" : "(Buschman and Miller, 2007; Buzsaki and Draguhn, 2004; Colgin et al., 2009; Fries, 2009; Singer and Gray, 1995)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Buschman and Miller, 2007; Buzsaki and Draguhn, 2004; Colgin et al., 2009; Fries, 2009; Singer and Gray, 1995). Gamma-band synchronization has been observed in humans using non-invasive imaging methods during visual ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2005.08.043", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "16216533", "abstract" : "Neuronal gamma-band (30-100 Hz) synchronization subserves fundamental functions in neuronal processing. However, different experimental approaches differ widely in their success in finding gamma-band activity. We aimed at linking animal and human studies of gamma-band activity and at preparing optimized methods for an in-depth investigation of the mechanisms and functions of gamma-band activity and gamma-band coherence in humans. In the first step described here, we maximized the signal-to-noise ratio with which we can observe visually induced gamma-band activity in human magnetoencephalographic recordings. We used a stimulus and task design that evoked strong gamma-band activity in animals and combined it with multi-taper methods for spectral analysis and adaptive spatial filtering for source analysis. With this approach, we found human visual gamma-band activity very reliably across subjects and across multiple recording sessions of a given subject. While increases in gamma-band activity are typically accompanied by decreases in alpha- and beta-band activity, the gamma-band enhancement was often the spectral component with the highest signal-to-noise ratio. Furthermore, some subjects demonstrated two clearly separate visually induced gamma bands, one around 40 Hz and another between 70 and 80 Hz. Gamma-band activity was sustained for the entire stimulation period, which was up to 3 s. The sources of gamma-band activity were in the calcarine sulcus in all subjects. The results localize human visual gamma-band activity in frequency, time and space and the described methods allow its further investigation with great sensitivity. \u00a9 2005 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Hoogenboom", "given" : "Nienke", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schoffelen", "given" : "Jan Mathijs", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Parkes", "given" : "Laura M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "764-773", "title" : "Localizing human visual gamma-band activity in frequency, time and space", "type" : "article-journal", "volume" : "29" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2012.12.038", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "23274186", "abstract" : "Increases in the power of neural oscillations in the gamma (>40Hz) band are a key signature of information processing in cortical neuronal networks. However, non-invasive detection of these very small oscillations is difficult due to the presence of potential artefacts (both muscular and ocular) in the same frequency band and requires highly optimised paradigms. Numerous studies have shown that the properties of visual gamma-band responses to simple pattern stimuli are highly tuned to the stimuli parameters used. The aim of this work was to compare gamma oscillation response properties across some of the more commonly used stimulus configurations. To do this, MEG and EEG recordings were made during the presentation of eight different stimulus types in a 2??2??2 design. For the first stimulus factor, \"Type\", the stimulus pattern was either an annulus grating or a square wave grating. For the second stimulus factor, \"Field\", stimuli were presented in either four visual field quadrants simultaneously or only in the lower left quadrant. Finally, for the \"Move\" factor, stimuli either drifted at 1.33??s-1 or were stationary. For MEG gamma band responses, the following main effects were observed, a) gamma-band power was increased for annular stimuli compared to square wave stimuli, b) gamma-band power was increased for full field stimuli compared to single quadrant stimuli and c) gamma-band power was larger for drifting compared to stationary stimuli and were of significantly higher frequency. For the detectors used, the signal to noise ratio was substantially higher for MEG than EEG. The advantages and disadvantages of the different types of stimulus types are discussed. ?? 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Singh", "given" : "K D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "223-230", "publisher" : "Elsevier Inc.", "title" : "Visual gamma oscillations: The effects of stimulus type, visual field coverage and stimulus motion on MEG and EEG recordings", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Hoogenboom et al., 2006; Muthukumaraswamy and Singh, 2013)", "plainTextFormattedCitation" : "(Hoogenboom et al., 2006; Muthukumaraswamy and Singh, 2013)", "previouslyFormattedCitation" : "(Hoogenboom et al., 2006; Muthukumaraswamy and Singh, 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Hoogenboom et al., 2006; Muthukumaraswamy and Singh, 2013), somatosensory ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1523/JNEUROSCI.5228-04.2006", "ISBN" : "1529-2401 (Electronic) 0270-6474 (Linking)", "PMID" : "16407546", "abstract" : "We investigated the effects of spatial-selective attention on oscillatory neuronal dynamics in a tactile delayed-match-to-sample task. Whole-head magnetoencephalography was recorded in healthy subjects while dot patterns were presented to their index fingers using Braille stimulators. The subjects' task was to report the reoccurrence of an initially presented sample pattern in a series of up to eight test stimuli that were presented unpredictably to their right or left index finger. Attention was cued to one side (finger) at the beginning of each trial, and subjects performed the task at the attended side, ignoring the unattended side. After stimulation, high-frequency gamma-band activity (60-95 Hz) in presumed primary somatosensory cortex (S1) was enhanced, whereas alpha- and beta-band activity were suppressed in somatosensory and occipital areas and then rebounded. Interestingly, despite the absence of any visual stimulation, we also found time-locked activation of medial occipital, presumably visual, cortex. Most relevant, spatial tactile attention enhanced stimulus-induced gamma-band activity in brain regions consistent with contralateral S1 and deepened and prolonged the stimulus induced suppression of beta- and alpha-band activity, maximal in parieto-occipital cortex. Additionally, the beta rebound over contralateral sensorimotor areas was suppressed. We hypothesize that spatial-selective attention enhances the saliency of sensory representations by synchronizing neuronal responses in early somatosensory cortex and thereby enhancing their impact on downstream areas and facilitating interareal processing. Furthermore, processing of tactile patterns also seems to recruit visual cortex and this even more so for attended compared with unattended stimuli.", "author" : [ { "dropping-particle" : "", "family" : "Bauer", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Peeters", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "edition" : "2006/01/13", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2006" ] ] }, "note" : "Bauer, Markus\nOostenveld, Robert\nPeeters, Maarten\nFries, Pascal\nJ Neurosci. 2006 Jan 11;26(2):490-501.", "page" : "490-501", "title" : "Tactile spatial attention enhances gamma-band activity in somatosensory cortex and reduces low-frequency activity in parieto-occipital areas", "type" : "article-journal", "volume" : "26" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Bauer et al., 2006)", "plainTextFormattedCitation" : "(Bauer et al., 2006)", "previouslyFormattedCitation" : "(Bauer et al., 2006)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Bauer et al., 2006) and auditory ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1073/pnas.88.20.8996", "ISBN" : "0027-8424 (Print)\\r0027-8424 (Linking)", "ISSN" : "0027-8424", "PMID" : "1924362", "abstract" : "We have discovered a ca. 40-Hz transient magnetic oscillatory response, evoked in the human brain by the onset of auditory stimuli, consisting of four or more cycles locked in phase to stimulus onset in approximately the 20- to 130-ms poststimulus interval. The response originates in the supratemporal auditory cortex, some millimeters deeper and anterior to the source of the larger-amplitude slow-wave M100 component of the evoked magnetic field and moves in a posterior arcing trajectory 1 cm or more in length. The oscillatory cortical activation elicited by auditory stimuli may be similar to the gamma-band cortical oscillations elicited by olfactory and visual stimuli and may represent an essential component of auditory perceptual processing.", "author" : [ { "dropping-particle" : "", "family" : "Pantev", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Makeig", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hoke", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Galambos", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hampson", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gallen", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proceedings of the National Academy of Sciences of the United States of America", "id" : "ITEM-1", "issue" : "October", "issued" : { "date-parts" : [ [ "1991" ] ] }, "page" : "8996-9000", "title" : "Human auditory evoked gamma-band magnetic fields.", "type" : "article-journal", "volume" : "88" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.04.074", "ISSN" : "1053-8119", "abstract" : "For efficient and fast encoding of our complex acoustic environment, not only aspects of bottom-up processing are significant, but rather top-down influences such as attention, memory, and anticipation promote specific behavior and perception. Neural oscillatory activity in the gamma-range (30-80??Hz) is discussed as a conceivable candidate to represent very rapid modulations of top-down factors. We investigated effects of anticipation on early gamma-band responses (GBRs) of the EEG and event-related potentials (ERPs) in response to tone sequences. These sequences were composed of six sinusoidal tones, which could be either regularly ascending or descending in frequency. Thus, the sequences reflected a good continuation of pitch, which also resulted in the buildup of strong expectancies for the upcoming stimulus within the sequence. However, some of the tone sequences contained a violation of the good continuation of pitch at the third or fifth tone position. The early phase-locked portion of the gamma-band activity was significantly increased when tones were in line with the good continuation of sequences compared to deviant tones. Further, a pronounced early negative ERP response, starting at 150??ms, was elicited by deviant tones at the third and fifth position. Our results support the notion that gamma-band oscillations reflect perceptual grouping processes of concurrent sounds and anticipatory top-down modulation, which involves some of the first stages of auditory information processing. ?? 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Schadow", "given" : "Jeanette", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lenz", "given" : "Daniel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dettler", "given" : "Nicole", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fr\u00fcnd", "given" : "Ingo", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Herrmann", "given" : "Christoph S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "2", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "651-658", "publisher" : "Elsevier Inc.", "title" : "NeuroImage Early gamma-band responses re fl ect anticipatory top-down modulation in the auditory cortex", "type" : "article-journal", "volume" : "47" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Pantev et al., 1991; Schadow et al., 2009)", "plainTextFormattedCitation" : "(Pantev et al., 1991; Schadow et al., 2009)", "previouslyFormattedCitation" : "(Pantev et al., 1991; Schadow et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Pantev et al., 1991; Schadow et al., 2009) stimulation. It is also known to be involved in higher cognitive functions such as memory processes ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/nn759", "ISBN" : "1097-6256 (Print)", "ISSN" : "1097-6256", "PMID" : "11694886", "abstract" : "In humans, distinct processes within the hippocampus and rhinal cortex support declarative memory formation. But do these medial temporal lobe (MTL) substructures directly cooperate in encoding new memories? Phase synchronization of gamma-band electroencephalogram (EEG) oscillations (around 40 Hz) is a general mechanism of transiently connecting neural assemblies. We recorded depth-EEG from within the MTL of epilepsy patients performing a memorization task. Successful as opposed to unsuccessful memory formation was accompanied by an initial elevation of rhinal-hippocampal gamma synchronization followed by a later desynchronization, suggesting that effective declarative memory formation is accompanied by a direct and temporarily limited cooperation between both MTL substructures.", "author" : [ { "dropping-particle" : "", "family" : "Fell", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Klaver", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lehnertz", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grunwald", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schaller", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Elger", "given" : "C E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fernandez", "given" : "G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature Neuroscience", "id" : "ITEM-1", "issue" : "12", "issued" : { "date-parts" : [ [ "2001" ] ] }, "page" : "1259-1264", "title" : "Human memory formation is accompanied by rhinal-hippocampal coupling and decoupling.", "type" : "article-journal", "volume" : "4" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1093/cercor/bhg084", "ISBN" : "1047-3211", "ISSN" : "10473211", "PMID" : "14615302", "abstract" : "Functional imaging of human cortex implicates a diverse network of brain regions supporting working memory \u2014 the capacity to hold and manipulate information for short periods of time. Although we are beginning to map out the brain networks supporting working memory, little is known about its physiological basis. We analyzed intracranial recordings from two epileptic patients as they performed a working memory task. Spectral analyses revealed that, in both patients, gamma (30\u201360 Hz) oscillations increased approximately linearly with memory load, tracking closely with memory load over the course of the trial. This constitutes the first evidence that gamma oscillations, widely implicated in perceptual processes, support the maintenance of multiple items in working memory.", "author" : [ { "dropping-particle" : "", "family" : "Howard", "given" : "Marc W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rizzuto", "given" : "Daniel S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Caplan", "given" : "Jeremy B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Madsen", "given" : "Joseph R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lisman", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Aschenbrenner-Scheibe", "given" : "Richard", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schulze-Bonhage", "given" : "Andreas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kahana", "given" : "Michael J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Cerebral Cortex", "id" : "ITEM-2", "issue" : "12", "issued" : { "date-parts" : [ [ "2003" ] ] }, "page" : "1369-1374", "title" : "Gamma Oscillations Correlate with Working Memory Load in Humans", "type" : "article-journal", "volume" : "13" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Fell et al., 2001; Howard et al., 2003)", "plainTextFormattedCitation" : "(Fell et al., 2001; Howard et al., 2003)", "previouslyFormattedCitation" : "(Fell et al., 2001; Howard et al., 2003)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Fell et al., 2001; Howard et al., 2003) and motor control ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "ISBN" : "0022-3077 (Print)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "9862895", "abstract" : "The electromyogram (EMG) of healthy humans demonstrates a tendency to rhythmic oscillations at around 40 Hz (the Piper rhythm) during strong voluntary contraction. Why motor units should discharge synchronously locked to such a high-frequency is unclear. We recorded whole scalp magnetoencephalographic (MEG) signals simultaneously with surface EMG from 10 healthy subjects. In eight subjects, coherence and time domain analyses demonstrated correspondence between the MEG signal, originating near or in the hand region of the motor cortex, and the 35- to 60-Hz EMG recorded during repeated maximal isometric contractions of the contralateral forearm extensor muscles. Three of these subjects also showed similar coherence during isometric contractions of moderate strength and slow extension movements of the wrist. In addition, coherence and time domain analyses demonstrated correspondence between the MEG signals originating near or in the foot area of the motor cortex and EMG recorded during repeated maximal isometric contractions of the contralateral tibialis anterior muscle in the 30- to 60-Hz range. Most important, the frequency at the peak of the coherence spectrum differed between forearm and leg by as much as 10 Hz in the same subject. In contrast, the peak of the coherence spectrum occurred during sustained weak contraction in the 20- to 30-Hz range similarly for both forearm and foot. The lag between EMG and MEG activity in the leg was similar to 15 ms greater than that seen in the forearm, an interval appropriate for conduction in fast pyramidal pathways. It is concluded that the Piper rhythm in muscle may be driven by a comparable oscillatory activity in the contralateral motor cortex. This cortical rhythmicity can be picked up in several types of movement and seems distinct from the 20- to 30-Hz rhythmicity recorded during weak sustained contractions.", "author" : [ { "dropping-particle" : "", "family" : "Brown", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Salenius", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rothwell", "given" : "J C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hari", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-1", "issue" : "6", "issued" : { "date-parts" : [ [ "1998" ] ] }, "page" : "2911-2917", "title" : "Cortical correlate of the piper rhythm in humans", "type" : "article-journal", "volume" : "80" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.04.178", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18511304", "abstract" : "There has been increasing interest in the functional role of high-frequency (> 30??Hz) cortical oscillations accompanying various sensorimotor and cognitive tasks in humans. Similar \"high gamma\" activity has been observed in the motor cortex, although the role of this activity in motor control is unknown. Using whole-head MEG recordings combined with advanced source localization methods, we identified high-frequency (65 to 80??Hz) gamma oscillations in the primary motor cortex during self-paced movements of the upper and lower limbs. Brief bursts of gamma activity were localized to the contralateral precentral gyrus (MI) during self-paced index finger abductions, elbow flexions and foot dorsiflexions. In comparison to lower frequency (10-30??Hz) sensorimotor rhythms that are bilaterally suppressed prior to and during movement (Jurkiewicz et al., 2006), high gamma activity increased only during movement, reaching maximal increase 100 to 250??ms following EMG onset, and was lateralized to contralateral MI, similar to findings from intracranial EEG studies. Peak frequency of gamma activity was significantly lower during foot dorsiflexion (67.4 ?? 5.2??Hz) than during finger abduction (75.3 ?? 4.4??Hz) and elbow flexion (73.9 ?? 3.7??Hz) although markedly similar for left and right movements of the same body part within subjects, suggesting activation of a common underlying network for gamma oscillations in the left and right motor cortex. These findings demonstrate that voluntary movements elicit high-frequency gamma oscillations in the primary motor cortex that are effector specific, and possibly reflect the activation of cortico-subcortical networks involved in the feedback control of discrete movements. ?? 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bells", "given" : "Sonya", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaetz", "given" : "William", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bostan", "given" : "Andreea C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "1", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "332-342", "title" : "Self-paced movements induce high-frequency gamma oscillations in primary motor cortex", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1093/brain/121.12.2301", "ISBN" : "0006-8950 (Print)", "ISSN" : "0006-8950", "PMID" : "9874481", "abstract" : "It has been shown in animals that neuronal activity in the 'gamma band' (>30 Hz) is associated with cortical activation and may play a role in multi-regional and multi-modal integration of cortical processing. Studies of gamma activity in human scalp EEG have typically focused on event-related synchronization (ERS) in the 40 Hz band. To assess further the gamma band ERS further, as an index of cortical activation and as a tool for human functional brain mapping, we recorded subdural electrocorticographic (ECoG) signals in five clinical subjects while they performed visual\u2013motor decision tasks designed to activate the representations of different body parts in sensorimotor cortex. ECoG spectral analysis utilized a mixed-effects analysis of variance model in which within-trial temporal dependencies were accounted for. Taking an exploratory approach, we studied gamma ERS in 10-Hz-wide bands (overlapping by 5 Hz) ranging from 30 to 100 Hz, and compared these findings with changes in the alpha (8\u201313 Hz) and beta (15\u201325 Hz) bands. Gamma ERS (observed in three out of subjects) occurred in two broad bands\u2014'low gamma' included the 35\u201345 and 40\u201350 Hz bands, and 'high gamma' the 75\u201385, 80\u201390, 85\u201395 and 90\u2013100 Hz bands. The temporal and spatial characteristics of low and high gamma ERS were distinct, suggesting relatively independent", "author" : [ { "dropping-particle" : "", "family" : "Crone", "given" : "Nathan E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miglioretti", "given" : "Diana L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gordon", "given" : "Barry", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lesser", "given" : "Ronald P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Brain", "id" : "ITEM-3", "issue" : "August 2016", "issued" : { "date-parts" : [ [ "1998" ] ] }, "page" : "2301-2315", "title" : "Functional mapping of human sensorimotor cortex with electrocorticographic spectral analysis II. Event-related synchronization in the gamma band", "type" : "article-journal", "volume" : "121" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.08.041", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19715762", "abstract" : "High gamma (HG) power changes during motor activity, especially at frequencies above 70\u00a0Hz, play an important role in functional cortical mapping and as control signals for BCI (brain-computer interface) applications. Most studies of HG activity have used ECoG (electrocorticography) which provides high-quality spatially localized signals, but is an invasive method. Recent studies have shown that non-invasive modalities such as EEG and MEG can also detect task-related HG power changes. We show here that a 27 channel EEG (electroencephalography) montage provides high-quality spatially localized signals non-invasively for HG frequencies ranging from 83 to 101\u00a0Hz. We used a generic head model, a weighted minimum norm least squares (MNLS) inverse method, and a self-paced finger movement paradigm. The use of an inverse method enables us to map the EEG onto a generic cortex model. We find the HG activity during the task to be well localized in the contralateral motor area. We find HG power increases prior to finger movement, with average latencies of 462\u00a0ms and 82\u00a0ms before EMG (electromyogram) onset. We also find significant phase-locking between contra- and ipsilateral motor areas over a similar HG frequency range; here the synchronization onset precedes the EMG by 400\u00a0ms. We also compare our results to ECoG data from a similar paradigm and find EEG mapping and ECoG in good agreement. Our findings demonstrate that mapped EEG provides information on two important parameters for functional mapping and BCI which are usually only found in HG of ECoG signals: spatially localized power increases and bihemispheric phase-locking. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Scherer", "given" : "R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sorensen", "given" : "L. B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-4", "issue" : "1", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "930-938", "publisher" : "Elsevier Inc.", "title" : "High gamma mapping using EEG", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.1016/j.neuroimage.2010.01.077", "ISBN" : "1095-9572 (Electronic)\\n1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "20116434", "abstract" : "We measured visually-cued motor responses in two developmentally separate groups of children and compared these responses to a group of adults. We hypothesized that if post-movement beta rebound (PMBR) depends on developmentally sensitive processes, PMBR will be greatest in adults and progressively decrease in children performing a basic motor task as a function of age.Twenty children (10 young children 4-6 years; 10 adolescent children 11-13 years) and 10 adults all had MEG recorded during separate recordings of right and left index finger movements.Beta band (15-30 Hz) event-related desynchronization (ERD) of bi-lateral sensorimotor areas was observed to increase significantly from both contralateral and ipsilateral MI with age. Movement-related gamma synchrony (60-90 Hz) was also observed from contralateral MI for each age group. However, PMBR was significantly reduced in the 4-6 year group and, while more prominent, remained significantly diminished in the adolescent (11-13 year) age group as compared to adults. PMBR measures were weak or absent in the youngest children tested and appear maximally from bilateral MI in adults. Thus PMBR may reflect an age-dependent inhibitory process of the primary motor cortex which comes on-line with normal development.Previous studies have shown PMBR may be observed from MI following a variety of movement-related tasks in adult participants - however, the origin and purpose of the PMBR is unclear. The current study shows that the expected PMBR from MI observed from adults is increasingly diminished in adolescent and young children respectively. A reduction in PMBR from children may reflect reduced motor cortical inhibition. Relatively less motor inhibition may facilitate neuronal plasticity and promote motor learning in children. ?? 2010 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Gaetz", "given" : "W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "MacDonald", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cheyne", "given" : "D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Snead", "given" : "O. C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-5", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "792-807", "publisher" : "Elsevier Inc.", "title" : "Neuromagnetic imaging of movement-related cortical oscillations in children and adults: Age predicts post-movement beta rebound", "type" : "article-journal", "volume" : "51" }, "uris" : [ "" ] }, { "id" : "ITEM-6", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-6", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] }, { "id" : "ITEM-7", "itemData" : { "DOI" : "10.1126/science.1107027", "ISBN" : "1095-9203 (Electronic)$\\backslash$n0036-8075 (Linking)", "ISSN" : "0036-8075", "PMID" : "15802603", "abstract" : "Neuronal groups can interact with each other even if they are widely separated. One group might modulate its firing rate or its internal oscillatory synchronization to influence another group. We propose that coherence between two neuronal groups is a mechanism of efficient interaction, because it renders mutual input optimally timed and thereby maximally effective. Modulations of subjects' readiness to respond in a simple reaction-time task were closely correlated with the strength of gamma-band (40 to 70 hertz) coherence between motor cortex and spinal cord neurons. This coherence may contribute to an effective corticospinal interaction and shortened reaction times.", "author" : [ { "dropping-particle" : "", "family" : "Schoffelen", "given" : "Jan-mathijs", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science (New York, N.Y.)", "id" : "ITEM-7", "issue" : "5718", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "111-113", "title" : "Neuronal coherence as a mechanism of effective corticospinal interaction.", "type" : "article-journal", "volume" : "308" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Brown et al., 1998; Cheyne et al., 2008; Crone et al., 1998; Darvas et al., 2010; Gaetz et al., 2010; Muthukumaraswamy, 2010; Schoffelen et al., 2005)", "plainTextFormattedCitation" : "(Brown et al., 1998; Cheyne et al., 2008; Crone et al., 1998; Darvas et al., 2010; Gaetz et al., 2010; Muthukumaraswamy, 2010; Schoffelen et al., 2005)", "previouslyFormattedCitation" : "(Brown et al., 1998; Cheyne et al., 2008; Crone et al., 1998; Darvas et al., 2010; Gaetz et al., 2010; Muthukumaraswamy, 2010; Schoffelen et al., 2005)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Brown et al., 1998; Cheyne et al., 2008; Crone et al., 1998; Darvas et al., 2010; Gaetz et al., 2010; Muthukumaraswamy, 2010; Schoffelen et al., 2005). Therefore, due to the functional importance of gamma frequency activity, characterising the underlying mechanisms of these responses is of great interest.The majority of previous work investigating the link between BOLD signals and gamma activity has been conducted using invasive electrode recordings of local-field potentials in humans ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1126/science.1110913", "ISBN" : "1529-2401 (Electronic)\\r0270-6474 (Linking)", "ISSN" : "0036-8075", "PMID" : "16081741", "abstract" : "Functional magnetic resonance imaging (fMRI) is an important tool for investigating human brain function, but the relationship between the hemodynamically based fMRI signals in the human brain and the underlying neuronal activity is unclear. We recorded single unit activity and local field potentials in auditory cortex of two neurosurgical patients and compared them with the fMRI signals of 11 healthy subjects during presentation of an identical movie segment. The predicted fMRI signals derived from single units and the measured fMRI signals from auditory cortex showed a highly significant correlation (r = 0.75, P < 10(-47)). Thus, fMRI signals can provide a reliable measure of the firing rate of human cortical neurons.", "author" : [ { "dropping-particle" : "", "family" : "Mukamel", "given" : "Roy", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gelbard", "given" : "Hagar", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Arieli", "given" : "Amos", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hasson", "given" : "Uri", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fried", "given" : "Itzhak", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Malach", "given" : "Rafael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science (New York, N.Y.)", "id" : "ITEM-1", "issue" : "5736", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "951-954", "title" : "Coupling between neuronal firing, field potentials, and FMRI in human auditory cortex.", "type" : "article-journal", "volume" : "309" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2016.08.001", "ISSN" : "10959572", "PMID" : "27498370", "abstract" : "In current fMRI studies designed to map BOLD changes related to interictal epileptiform discharges (IED), which are recorded on simultaneous EEG, the information contained in the morphology and field extent of the EEG events is exclusively used for their classification. Usually, a BOLD predictor based on IED onset times alone is constructed, effectively treating all events as identical. We used intracranial EEG (icEEG)-fMRI data simultaneously recorded in humans to investigate the effect of including any of the features: amplitude, width (duration), slope of the rising phase, energy (area under the curve), or spatial field extent (number of contacts over which the sharp wave was observed) of the fast wave of the IED (the sharp wave), into the BOLD model, to better understand the neurophysiological origin of sharp wave-related BOLD changes, in the immediate vicinity of the recording contacts. Among the features considered, the width was the only one found to explain a significant amount of additional variance, suggesting that the amplitude of the BOLD signal depends more on the duration of the underlying field potential (reflected in the sharp wave width) than on the degree of neuronal activity synchrony (reflected in the sharp wave amplitude), and, consequently, that including inter-event variations of the sharp wave width in the BOLD signal model may increase the sensitivity of forthcoming EEG-fMRI studies of epileptic activity.", "author" : [ { "dropping-particle" : "", "family" : "Murta", "given" : "T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hu", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tierney", "given" : "T. M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Chaudhary", "given" : "U. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Walker", "given" : "M. C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Carmichael", "given" : "D. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Figueiredo", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lemieux", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "371-380", "title" : "A study of the electro-haemodynamic coupling using simultaneously acquired intracranial EEG and fMRI data in humans", "type" : "article-journal", "volume" : "142" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.cub.2007.06.066", "ISBN" : "0960-9822 (Print)\\r0960-9822 (Linking)", "ISSN" : "09609822", "PMID" : "17686438", "abstract" : "Background: To what extent is activity of individual neurons coupled to the local field potential (LFP) and to blood-oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI)? This issue is of high significance for understanding brain function and for relating animal studies to fMRI, yet it is still under debate. Results: Here we report data from simultaneous recordings of isolated unit activity and LFP by using multiple electrodes in the human auditory cortex. We found a wide range of coupling levels between the activity of individual neurons and gamma LFP. However, this large variability could be predominantly explained (r = 0.66) by the degree of firing-rate correlations between neighboring neurons. Importantly, this phenomenon occurred during both sensory stimulation and spontaneous activity. Concerning the coupling of neuronal activity to BOLD fMRI, we found that gamma LFP was well coupled to BOLD measured across different individuals (r = 0.62). By contrast, the coupling of single units to BOLD was highly variable and, again, tightly related to interneuronal-firing-rate correlations (r = 0.70). Conclusions: Our results offer a resolution to a central controversy regarding the coupling between neurons, LFP, and BOLD signals by demonstrating, for the first time, that the coupling of single units to the other measures is variable yet it is tightly related to the degree of interneuronal correlations in the human auditory cortex. \u00a9 2007 Elsevier Ltd. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Nir", "given" : "Yuval", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fisch", "given" : "Lior", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mukamel", "given" : "Roy", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gelbard-Sagiv", "given" : "Hagar", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Arieli", "given" : "Amos", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fried", "given" : "Itzhak", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Malach", "given" : "Rafael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Current Biology", "id" : "ITEM-3", "issue" : "15", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "1275-1285", "title" : "Coupling between Neuronal Firing Rate, Gamma LFP, and BOLD fMRI Is Related to Interneuronal Correlations", "type" : "article-journal", "volume" : "17" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mukamel et al., 2005; Murta et al., 2016; Nir et al., 2007)", "plainTextFormattedCitation" : "(Mukamel et al., 2005; Murta et al., 2016; Nir et al., 2007)", "previouslyFormattedCitation" : "(Mukamel et al., 2005; Murta et al., 2016; Nir et al., 2007)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mukamel et al., 2005; Murta et al., 2016; Nir et al., 2007), primates ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/35084005", "abstract" : "Functional magnetic resonance imaging (fMRI) is widely used to study the operational organization of the human brain, but the exact relationship between the measured fMRI signal and the underlying neural activity is unclear. Here we present simultaneous intracortical recordings of neural signals and fMRI responses. We compared local field potentials (LFPs), single- and multi-unit spiking activity with highly spatio-temporally resolved blood-oxygen-level-dependent (BOLD) fMRI responses from the visual cortex of monkeys. The largest magnitude changes were observed in LFPs, which at recording sites characterized by transient responses were the only signal that significantly correlated with the haemodynamic response. Linear systems analysis on a trial-by-trial basis showed that the impulse response of the neurovascular system is both animal- and site-specific, and that LFPs yield a better estimate of BOLD responses than the multi-unit responses. These findings suggest that the BOLD contrast mechanism reflects the input and intracortical processing of a given area rather than its spiking output.", "author" : [ { "dropping-particle" : "", "family" : "Logothetis", "given" : "N K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pauls", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Augath", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Trinath", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oeltermann", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature", "id" : "ITEM-1", "issue" : "6843", "issued" : { "date-parts" : [ [ "2001" ] ] }, "page" : "150-157", "title" : "Neurophysiological investigation of the basis of the fMRI signal", "type" : "article-journal", "volume" : "412" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "32/4/1395 [pii] 10.1523/JNEUROSCI.3985-11.2012", "ISBN" : "1529-2401 (Electronic) 0270-6474 (Linking)", "PMID" : "22279224", "abstract" : "There is growing evidence that several components of the mass neural activity contributing to the local field potential (LFP) can be partly separated by decomposing the LFP into nonoverlapping frequency bands. Although the blood oxygen level-dependent (BOLD) signal has been found to correlate preferentially with specific frequency bands of the LFP, it is still unclear whether the BOLD signal relates to the activity expressed by each LFP band independently of the others or if, instead, it also reflects specific relationships among different bands. We investigated these issues by recording, simultaneously and with high spatiotemporal resolution, BOLD signal and LFP during spontaneous activity in early visual cortices of anesthetized monkeys (Macaca mulatta). We used information theory to characterize the statistical dependency between BOLD and LFP. We found that the alpha (8-12 Hz), beta (18-30 Hz), and gamma (40-100 Hz) LFP bands were informative about the BOLD signal. In agreement with previous studies, gamma was the most informative band. Both increases and decreases in BOLD signal reliably followed increases and decreases in gamma power. However, both alpha and beta power signals carried information about BOLD that was largely complementary to that carried by gamma power. In particular, the relationship between alpha and gamma power was reflected in the amplitude of the BOLD signal, while the relationship between beta and gamma bands was reflected in the latency of BOLD with respect to significant changes in gamma power. These results lay the basis for identifying contributions of different neural pathways to cortical processing using fMRI.", "author" : [ { "dropping-particle" : "", "family" : "Magri", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schridde", "given" : "U", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Murayama", "given" : "Y", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Panzeri", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Logothetis", "given" : "N K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "edition" : "2012/01/27", "id" : "ITEM-2", "issue" : "4", "issued" : { "date-parts" : [ [ "2012" ] ] }, "note" : "Magri, Cesare\nSchridde, Ulrich\nMurayama, Yusuke\nPanzeri, Stefano\nLogothetis, Nikos K\nComparative Study\nResearch Support, Non-U.S. Gov't\nUnited States\nThe Journal of neuroscience : the official journal of the Society for Neuroscience\nJ Neurosci. 2012 Jan 25;32(4):1395-407.", "page" : "1395-1407", "title" : "The amplitude and timing of the BOLD signal reflects the relationship between local field potential power at different frequencies", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1126/science.1110948", "ISSN" : "0036-8075", "abstract" : "Functional imaging methods monitor neural activity by measuring hemodynamic signals. These are more closely related to local field potentials (LFPs) than to action potentials. We simultaneously recorded electrical and hemodynamic responses in the cat visual cortex. Increasing stimulus strength enhanced spiking activity, high-frequency LFP oscillations, and hemodynamic responses. With constant stimulus intensity, the hemodynamic response fluctuated; these fluctuations were only loosely related to action potential frequency but tightly correlated to the power of LFP oscillations in the gamma range. These oscillations increase with the synchrony of synaptic events, which suggests a close correlation between hemodynamic responses and neuronal synchronization.", "author" : [ { "dropping-particle" : "", "family" : "Niessing J, Ebisch B, Schmidt K, Niessing M, Singer W, Galuske R", "given" : "", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science", "id" : "ITEM-3", "issue" : "5736", "issued" : { "date-parts" : [ [ "2005", "8", "5" ] ] }, "page" : "948-951", "title" : "Hemodynamic Signals Correlate Tightly with Synchronized Gamma Oscillations", "type" : "article-journal", "volume" : "309" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "0913110107 [pii] 10.1073/pnas.0913110107", "ISBN" : "1091-6490 (Electronic) 0027-8424 (Linking)", "PMID" : "20439733", "abstract" : "Functional MRI (fMRI) has uncovered widespread hemodynamic fluctuations in the brain during rest. Recent electroencephalographic work in humans and microelectrode recordings in anesthetized monkeys have shown this activity to be correlated with slow changes in neural activity. Here we report that the spontaneous fluctuations in the local field potential (LFP) measured from a single cortical site in monkeys at rest exhibit widespread, positive correlations with fMRI signals over nearly the entire cerebral cortex. This correlation was especially consistent in a band of upper gamma-range frequencies (40-80 Hz), for which the hemodynamic signal lagged the neural signal by 6-8 s. A strong, positive correlation was also observed in a band of lower frequencies (2-15 Hz), albeit with a lag closer to zero. The global pattern of correlation with spontaneous fMRI fluctuations was similar whether the LFP signal was measured in occipital, parietal, or frontal electrodes. This coupling was, however, dependent on the monkey's behavioral state, being stronger and anticipatory when the animals' eyes were closed. These results indicate that the often discarded global component of fMRI fluctuations measured during the resting state is tightly coupled with underlying neural activity.", "author" : [ { "dropping-particle" : "", "family" : "Scholvinck", "given" : "M L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Maier", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ye", "given" : "F Q", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Duyn", "given" : "J H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leopold", "given" : "D A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "edition" : "2010/05/05", "id" : "ITEM-4", "issue" : "22", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Scholvinck, Marieke L\nMaier, Alexander\nYe, Frank Q\nDuyn, Jeff H\nLeopold, David A\nWellcome Trust/United Kingdom\nResearch Support, N.I.H., Extramural\nResearch Support, Non-U.S. Gov't\nUnited States\nProceedings of the National Academy of Sciences of the United States of America\nProc Natl Acad Sci U S A. 2010 Jun 1;107(22):10238-43. Epub 2010 May 3.", "page" : "10238-10243", "title" : "Neural basis of global resting-state fMRI activity", "type" : "article-journal", "volume" : "107" }, "uris" : [ "" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.1038/nn1977", "ISBN" : "1097-6256 (Print) 1097-6256 (Linking)", "PMID" : "17828254", "abstract" : "In noninvasive neuroimaging, neural activity is inferred from local fluctuations in deoxyhemoglobin. A fundamental question of functional magnetic resonance imaging (fMRI) is whether the inferred neural activity is driven primarily by synaptic or spiking activity. The answer is critical for the interpretation of the blood oxygen level-dependent (BOLD) signal in fMRI. Here, we have used well-established visual-system circuitry to create a stimulus that elicits synaptic activity without associated spike discharge. In colocalized recordings of neural and metabolic activity in cat primary visual cortex, we observed strong coupling between local field potentials (LFPs) and changes in tissue oxygen concentration in the absence of spikes. These results imply that the BOLD signal is more closely coupled to synaptic activity.", "author" : [ { "dropping-particle" : "", "family" : "Viswanathan", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Freeman", "given" : "R D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nat Neurosci", "edition" : "2007/09/11", "id" : "ITEM-5", "issue" : "10", "issued" : { "date-parts" : [ [ "2007" ] ] }, "note" : "Viswanathan, Ahalya\nFreeman, Ralph D\nEY01175/EY/NEI NIH HHS/\nEY03716/EY/NEI NIH HHS/\nNat Neurosci. 2007 Oct;10(10):1308-12. Epub 2007 Sep 9.", "page" : "1308-1312", "title" : "Neurometabolic coupling in cerebral cortex reflects synaptic more than spiking activity", "type" : "article-journal", "volume" : "10" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Logothetis et al., 2001; Magri et al., 2012; Niessing J, Ebisch B, Schmidt K, Niessing M, Singer W, Galuske R, 2005; Scholvinck et al., 2010; Viswanathan and Freeman, 2007)", "manualFormatting" : "(Logothetis et al., 2001; Magri et al., 2012; Niessing et al., 2005; Scholvinck et al., 2010; Viswanathan and Freeman, 2007)", "plainTextFormattedCitation" : "(Logothetis et al., 2001; Magri et al., 2012; Niessing J, Ebisch B, Schmidt K, Niessing M, Singer W, Galuske R, 2005; Scholvinck et al., 2010; Viswanathan and Freeman, 2007)", "previouslyFormattedCitation" : "(Logothetis et al., 2001; Magri et al., 2012; Niessing J, Ebisch B, Schmidt K, Niessing M, Singer W, Galuske R, 2005; Scholvinck et al., 2010; Viswanathan and Freeman, 2007)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Logothetis et al., 2001; Magri et al., 2012; Niessing et al., 2005; Scholvinck et al., 2010; Viswanathan and Freeman, 2007) and rodents ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1523/JNEUROSCI.2339-14.2015", "ISBN" : "1529-2401 (Electronic) 0270-6474 (Linking)", "ISSN" : "0270-6474", "PMID" : "25788681", "abstract" : "Studies that use prolonged periods of sensory stimulation report associations between regional reductions in neural activity and negative blood oxygenation level-dependent (BOLD) signaling. However, the neural generators of the negative BOLD response remain to be characterized. Here, we use single-impulse electrical stimulation of the whisker pad in the anesthetized rat to identify components of the neural response that are related to \" negative \" hemodynamic changes in the brain. Laminar multiunit activity and local field potential recordings of neural activity were performed concurrently with two-dimensional optical imaging spectroscopy measuring hemodynamic changes. Repeated measurements over multiple stimulation trials revealed significant variations in neural responses across session and animal datasets. Within this variation, we found robust long-latency decreases (300 and 2000 ms after stimulus presentation) in gamma-band power (30 \u2013 80 Hz) in the middle-superficial cortical layers in regions surrounding the activated whisker barrel cortex. This reduc-tion in gamma frequency activity was associated with corresponding decreases in the hemodynamic responses that drive the negative BOLD signal. These findings suggest a close relationship between BOLD responses and neural events that operate over time scales that outlast the initiating sensory stimulus, and provide important insights into the neurophysiological basis of negative neuroimaging signals.", "author" : [ { "dropping-particle" : "", "family" : "Boorman", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Harris", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bruyns-Haylett", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kennerley", "given" : "A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Zheng", "given" : "Y.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Martin", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Redgrave", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Berwick", "given" : "J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neuroscience", "id" : "ITEM-1", "issue" : "11", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "4641\u20134656", "title" : "Long-Latency Reductions in Gamma Power Predict Hemodynamic Changes That Underlie the Negative BOLD Signal", "type" : "article-journal", "volume" : "35" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2011.12.082", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "22245345", "abstract" : "The simultaneous recordings of neuronal and hemodynamic signals have revealed a significant involvement of high frequency bands (e.g., gamma range, 25-70Hz) in neurovascular coupling. However, the dependence on a physiological parameter is unknown. In this study, we performed simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) recordings in 12 Wistar rats using a conventional forepaw stimulation paradigm and concurrently monitored the systemic physiological parameters of the partial pressure of arterial oxygen, partial pressure of arterial carbon dioxide, pH, mean arterial blood pressure, and heart rate through the rat femoral artery. The high frequency bands in the artifact-free EEG signals, especially those in the gamma range, demonstrated a maximum correlation with fMRI signals in the rat somatosensory cortex. A multiple linear regression analysis demonstrated that the correlation coefficient between the gamma power and fMRI signal depended on the actual values of the physiological parameters (R 2=0.20, p<0.05), whereas the gamma power and fMRI signal by itself were independent. Among the parameters, the heart rate had a statistically significant slope (95% CI: 0.00027-0.0016, p<0.01) in a multiple linear regression model. These results indicate that neurovascular coupling is mainly driven by gamma oscillations, as expected, but coupling or potential decoupling is strongly influenced by systemic physiological parameters, which dynamically reflect the baseline vital status of the subject. ?? 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Sumiyoshi", "given" : "Akira", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Suzuki", "given" : "Hideaki", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ogawa", "given" : "Takeshi", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Riera", "given" : "Jorge J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Shimokawa", "given" : "Hiroaki", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kawashima", "given" : "Ryuta", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "1", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "738-746", "title" : "Coupling between gamma oscillation and fMRI signal in the rat somatosensory cortex: Its dependence on systemic physiological parameters", "type" : "article-journal", "volume" : "60" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Boorman et al., 2015; Sumiyoshi et al., 2012)", "plainTextFormattedCitation" : "(Boorman et al., 2015; Sumiyoshi et al., 2012)", "previouslyFormattedCitation" : "(Boorman et al., 2015; Sumiyoshi et al., 2012)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Boorman et al., 2015; Sumiyoshi et al., 2012). These studies showed the BOLD response is more strongly coupled to gamma frequency activity, compared with the activity in the lower (<30Hz) frequency bands.Whilst providing novel insights into neurovascular coupling, findings from invasive animal recordings cannot be easily extrapolated to scalp electrophysiological recordings due to differences in the recording references used and in the spatial scale of the neuronal populations involved in generating the signals ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2005.01.009", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "15862200", "abstract" : "Recent animal studies highlighting the relationship between functional imaging signals and the underlying neuronal activity have revealed the potential capabilities of non-invasive methods. However, the valuable exchange of information between animal and human studies remains restricted by the limited evidence of direct physiological links between species. In this study we used magnetoencephalography (MEG) to investigate the occurrence of 30-70 Hz (gamma) oscillations in human visual cortex, induced by the presentation of visual stimuli of varying contrast. These oscillations, well described in the animal literature, were observed in retinotopically concordant locations of visual cortex and show striking similarity to those found in primate visual cortex using surgically implanted electrodes. The amplitude of the gamma oscillations increases linearly with stimulus contrast in strong correlation with the gamma oscillations found in the local field potential (LFP) of the macaque. We demonstrate that non-invasive magnetic field measurements of gamma oscillations in human visual cortex concur with invasive measures of activation in primate visual cortex, suggesting both a direct representation of underlying neuronal activity and a concurrence between human and primate cortical activity. \u00a9 2005 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Hall", "given" : "Stephen D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Holliday", "given" : "Ian E.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hillebrand", "given" : "Arjan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Singh", "given" : "Krish D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furlong", "given" : "Paul L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hadjipapas", "given" : "Avgis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barnes", "given" : "Gareth R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "13-17", "title" : "The missing link: Analogous human and primate cortical gamma oscillations", "type" : "article-journal", "volume" : "26" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Hall et al., 2005)", "plainTextFormattedCitation" : "(Hall et al., 2005)", "previouslyFormattedCitation" : "(Hall et al., 2005)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Hall et al., 2005). In addition, although the coupling between BOLD and gamma-LFP activity is widely cited as principle evidence for the neural underpinnings of haemodynamic based functional neuroimaging, the majority of these seminal studies have been conducted in visual cortex ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/35084005", "abstract" : "Functional magnetic resonance imaging (fMRI) is widely used to study the operational organization of the human brain, but the exact relationship between the measured fMRI signal and the underlying neural activity is unclear. Here we present simultaneous intracortical recordings of neural signals and fMRI responses. We compared local field potentials (LFPs), single- and multi-unit spiking activity with highly spatio-temporally resolved blood-oxygen-level-dependent (BOLD) fMRI responses from the visual cortex of monkeys. The largest magnitude changes were observed in LFPs, which at recording sites characterized by transient responses were the only signal that significantly correlated with the haemodynamic response. Linear systems analysis on a trial-by-trial basis showed that the impulse response of the neurovascular system is both animal- and site-specific, and that LFPs yield a better estimate of BOLD responses than the multi-unit responses. These findings suggest that the BOLD contrast mechanism reflects the input and intracortical processing of a given area rather than its spiking output.", "author" : [ { "dropping-particle" : "", "family" : "Logothetis", "given" : "N K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pauls", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Augath", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Trinath", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oeltermann", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature", "id" : "ITEM-1", "issue" : "6843", "issued" : { "date-parts" : [ [ "2001" ] ] }, "page" : "150-157", "title" : "Neurophysiological investigation of the basis of the fMRI signal", "type" : "article-journal", "volume" : "412" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1038/nn1977", "ISBN" : "1097-6256 (Print) 1097-6256 (Linking)", "PMID" : "17828254", "abstract" : "In noninvasive neuroimaging, neural activity is inferred from local fluctuations in deoxyhemoglobin. A fundamental question of functional magnetic resonance imaging (fMRI) is whether the inferred neural activity is driven primarily by synaptic or spiking activity. The answer is critical for the interpretation of the blood oxygen level-dependent (BOLD) signal in fMRI. Here, we have used well-established visual-system circuitry to create a stimulus that elicits synaptic activity without associated spike discharge. In colocalized recordings of neural and metabolic activity in cat primary visual cortex, we observed strong coupling between local field potentials (LFPs) and changes in tissue oxygen concentration in the absence of spikes. These results imply that the BOLD signal is more closely coupled to synaptic activity.", "author" : [ { "dropping-particle" : "", "family" : "Viswanathan", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Freeman", "given" : "R D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nat Neurosci", "edition" : "2007/09/11", "id" : "ITEM-2", "issue" : "10", "issued" : { "date-parts" : [ [ "2007" ] ] }, "note" : "Viswanathan, Ahalya\nFreeman, Ralph D\nEY01175/EY/NEI NIH HHS/\nEY03716/EY/NEI NIH HHS/\nNat Neurosci. 2007 Oct;10(10):1308-12. Epub 2007 Sep 9.", "page" : "1308-1312", "title" : "Neurometabolic coupling in cerebral cortex reflects synaptic more than spiking activity", "type" : "article-journal", "volume" : "10" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Logothetis et al., 2001; Viswanathan and Freeman, 2007)", "plainTextFormattedCitation" : "(Logothetis et al., 2001; Viswanathan and Freeman, 2007)", "previouslyFormattedCitation" : "(Logothetis et al., 2001; Viswanathan and Freeman, 2007)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Logothetis et al., 2001; Viswanathan and Freeman, 2007), with some exceptions in auditory cortex ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1126/science.1110913", "ISBN" : "1529-2401 (Electronic)\\r0270-6474 (Linking)", "ISSN" : "0036-8075", "PMID" : "16081741", "abstract" : "Functional magnetic resonance imaging (fMRI) is an important tool for investigating human brain function, but the relationship between the hemodynamically based fMRI signals in the human brain and the underlying neuronal activity is unclear. We recorded single unit activity and local field potentials in auditory cortex of two neurosurgical patients and compared them with the fMRI signals of 11 healthy subjects during presentation of an identical movie segment. The predicted fMRI signals derived from single units and the measured fMRI signals from auditory cortex showed a highly significant correlation (r = 0.75, P < 10(-47)). Thus, fMRI signals can provide a reliable measure of the firing rate of human cortical neurons.", "author" : [ { "dropping-particle" : "", "family" : "Mukamel", "given" : "Roy", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gelbard", "given" : "Hagar", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Arieli", "given" : "Amos", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hasson", "given" : "Uri", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fried", "given" : "Itzhak", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Malach", "given" : "Rafael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Science (New York, N.Y.)", "id" : "ITEM-1", "issue" : "5736", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "951-954", "title" : "Coupling between neuronal firing, field potentials, and FMRI in human auditory cortex.", "type" : "article-journal", "volume" : "309" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mukamel et al., 2005)", "plainTextFormattedCitation" : "(Mukamel et al., 2005)", "previouslyFormattedCitation" : "(Mukamel et al., 2005)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mukamel et al., 2005). A wider understanding in other brain regions, for example sensorimotor cortex, is important to fully establish the fundamental nature of the gamma-BOLD relationship. Such investigations are particularly important given the recent doubt cast on the functional importance of narrow-band gamma responses in visual cortex ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1093/cercor/bhu091", "ISBN" : "1460-2199 (Electronic)$\\$r1047-3211 (Linking)", "ISSN" : "1460-2199", "PMID" : "24855114", "abstract" : "A striking feature of some field potential recordings in visual cortex is a rhythmic oscillation within the gamma band (30-80 Hz). These oscillations have been proposed to underlie computations in perception, attention, and information transmission. Recent studies of cortical field potentials, including human electrocorticography (ECoG), have emphasized another signal within the gamma band, a nonoscillatory, broadband signal, spanning 80-200 Hz. It remains unclear under what conditions gamma oscillations are elicited in visual cortex, whether they are necessary and ubiquitous in visual encoding, and what relationship they have to nonoscillatory, broadband field potentials. We demonstrate that ECoG responses in human visual cortex (V1/V2/V3) can include robust narrowband gamma oscillations, and that these oscillations are reliably elicited by some spatial contrast patterns (luminance gratings) but not by others (noise patterns and many natural images). The gamma oscillations can be conspicuous and robust, but because they are absent for many stimuli, which observers can see and recognize, the oscillations are not necessary for seeing. In contrast, all visual stimuli induced broadband spectral changes in ECoG responses. Asynchronous neural signals in visual cortex, reflected in the broadband ECoG response, can support transmission of information for perception and recognition in the absence of pronounced gamma oscillations.", "author" : [ { "dropping-particle" : "", "family" : "Hermes", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wandell", "given" : "B a", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Winawer", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Cerebral cortex (New York, N.Y. : 1991)", "id" : "ITEM-1", "issue" : "September", "issued" : { "date-parts" : [ [ "2014" ] ] }, "page" : "1-9", "title" : "Stimulus Dependence of Gamma Oscillations in Human Visual Cortex.", "type" : "article-journal" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Hermes et al., 2014)", "plainTextFormattedCitation" : "(Hermes et al., 2014)", "previouslyFormattedCitation" : "(Hermes et al., 2014)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Hermes et al., 2014), and the BOLD correlates of broader high-frequency activity ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.cub.2013.05.001", "ISBN" : "0960-9822", "ISSN" : "09609822", "PMID" : "23770184", "abstract" : "BACKGROUND Activity in the living human brain can be studied using multiple methods, spanning a wide range of spatial and temporal resolutions. We investigated the relationship between electric field potentials measured with electrocorticography (ECoG) and the blood oxygen level-dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI). We set out to explain the full set of measurements by modeling the underlying neural circuits. RESULTS ECoG responses in visual cortex can be separated into two visually driven components. One component is a specific temporal response that follows each stimulus contrast reversal (\"stimulus locked\"); the other component is an increase in the response variance (\"asynchronous\"). For electrodes in visual cortex (V1, V2, V3), the two measures respond to stimuli in the same region of visual space, but they have different spatial summation properties. The stimulus-locked ECoG component sums contrast approximately linearly across space; spatial summation in the asynchronous ECoG component is subadditive. Spatial summation measured using BOLD closely matches the asynchronous component. We created a neural simulation that accurately captures the main features of the ECoG time series; in the simulation, the stimulus-locked and asynchronous components arise from different neural circuits. CONCLUSIONS These observations suggest that the two ECoG components arise from different neural sources within the same cortical region. The spatial summation measurements and simulations suggest that the BOLD response arises primarily from neural sources that generate the asynchronous broadband ECoG component.", "author" : [ { "dropping-particle" : "", "family" : "Winawer", "given" : "Jonathan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kay", "given" : "Kendrick N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Foster", "given" : "Brett L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rauschecker", "given" : "Andreas M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Parvizi", "given" : "Josef", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wandell", "given" : "Brian A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Current Biology", "id" : "ITEM-1", "issue" : "13", "issued" : { "date-parts" : [ [ "2013", "7", "8" ] ] }, "page" : "1145-1153", "title" : "Asynchronous Broadband Signals Are the Principal Source of the BOLD Response in Human Visual Cortex", "type" : "article-journal", "volume" : "23" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Winawer et al., 2013)", "plainTextFormattedCitation" : "(Winawer et al., 2013)", "previouslyFormattedCitation" : "(Winawer et al., 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Winawer et al., 2013). Therefore non-invasive simultaneous EEG-fMRI recordings in humans offer many potential advantages for relating gamma and BOLD signals. Possibilities include extending previous studies suggestions of a strong gamma-BOLD relationship by investigating this coupling in motor paradigms, which have been widely shown to induce robust increases in gamma power ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.04.178", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18511304", "abstract" : "There has been increasing interest in the functional role of high-frequency (> 30??Hz) cortical oscillations accompanying various sensorimotor and cognitive tasks in humans. Similar \"high gamma\" activity has been observed in the motor cortex, although the role of this activity in motor control is unknown. Using whole-head MEG recordings combined with advanced source localization methods, we identified high-frequency (65 to 80??Hz) gamma oscillations in the primary motor cortex during self-paced movements of the upper and lower limbs. Brief bursts of gamma activity were localized to the contralateral precentral gyrus (MI) during self-paced index finger abductions, elbow flexions and foot dorsiflexions. In comparison to lower frequency (10-30??Hz) sensorimotor rhythms that are bilaterally suppressed prior to and during movement (Jurkiewicz et al., 2006), high gamma activity increased only during movement, reaching maximal increase 100 to 250??ms following EMG onset, and was lateralized to contralateral MI, similar to findings from intracranial EEG studies. Peak frequency of gamma activity was significantly lower during foot dorsiflexion (67.4 ?? 5.2??Hz) than during finger abduction (75.3 ?? 4.4??Hz) and elbow flexion (73.9 ?? 3.7??Hz) although markedly similar for left and right movements of the same body part within subjects, suggesting activation of a common underlying network for gamma oscillations in the left and right motor cortex. These findings demonstrate that voluntary movements elicit high-frequency gamma oscillations in the primary motor cortex that are effector specific, and possibly reflect the activation of cortico-subcortical networks involved in the feedback control of discrete movements. ?? 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bells", "given" : "Sonya", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaetz", "given" : "William", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bostan", "given" : "Andreea C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "332-342", "title" : "Self-paced movements induce high-frequency gamma oscillations in primary motor cortex", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1093/brain/121.12.2301", "ISBN" : "0006-8950 (Print)", "ISSN" : "0006-8950", "PMID" : "9874481", "abstract" : "It has been shown in animals that neuronal activity in the 'gamma band' (>30 Hz) is associated with cortical activation and may play a role in multi-regional and multi-modal integration of cortical processing. Studies of gamma activity in human scalp EEG have typically focused on event-related synchronization (ERS) in the 40 Hz band. To assess further the gamma band ERS further, as an index of cortical activation and as a tool for human functional brain mapping, we recorded subdural electrocorticographic (ECoG) signals in five clinical subjects while they performed visual\u2013motor decision tasks designed to activate the representations of different body parts in sensorimotor cortex. ECoG spectral analysis utilized a mixed-effects analysis of variance model in which within-trial temporal dependencies were accounted for. Taking an exploratory approach, we studied gamma ERS in 10-Hz-wide bands (overlapping by 5 Hz) ranging from 30 to 100 Hz, and compared these findings with changes in the alpha (8\u201313 Hz) and beta (15\u201325 Hz) bands. Gamma ERS (observed in three out of subjects) occurred in two broad bands\u2014'low gamma' included the 35\u201345 and 40\u201350 Hz bands, and 'high gamma' the 75\u201385, 80\u201390, 85\u201395 and 90\u2013100 Hz bands. The temporal and spatial characteristics of low and high gamma ERS were distinct, suggesting relatively independent", "author" : [ { "dropping-particle" : "", "family" : "Crone", "given" : "Nathan E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miglioretti", "given" : "Diana L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gordon", "given" : "Barry", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lesser", "given" : "Ronald P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Brain", "id" : "ITEM-2", "issue" : "August 2016", "issued" : { "date-parts" : [ [ "1998" ] ] }, "page" : "2301-2315", "title" : "Functional mapping of human sensorimotor cortex with electrocorticographic spectral analysis II. Event-related synchronization in the gamma band", "type" : "article-journal", "volume" : "121" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuroimage.2010.01.077", "ISBN" : "1095-9572 (Electronic)\\n1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "20116434", "abstract" : "We measured visually-cued motor responses in two developmentally separate groups of children and compared these responses to a group of adults. We hypothesized that if post-movement beta rebound (PMBR) depends on developmentally sensitive processes, PMBR will be greatest in adults and progressively decrease in children performing a basic motor task as a function of age.Twenty children (10 young children 4-6 years; 10 adolescent children 11-13 years) and 10 adults all had MEG recorded during separate recordings of right and left index finger movements.Beta band (15-30 Hz) event-related desynchronization (ERD) of bi-lateral sensorimotor areas was observed to increase significantly from both contralateral and ipsilateral MI with age. Movement-related gamma synchrony (60-90 Hz) was also observed from contralateral MI for each age group. However, PMBR was significantly reduced in the 4-6 year group and, while more prominent, remained significantly diminished in the adolescent (11-13 year) age group as compared to adults. PMBR measures were weak or absent in the youngest children tested and appear maximally from bilateral MI in adults. Thus PMBR may reflect an age-dependent inhibitory process of the primary motor cortex which comes on-line with normal development.Previous studies have shown PMBR may be observed from MI following a variety of movement-related tasks in adult participants - however, the origin and purpose of the PMBR is unclear. The current study shows that the expected PMBR from MI observed from adults is increasingly diminished in adolescent and young children respectively. A reduction in PMBR from children may reflect reduced motor cortical inhibition. Relatively less motor inhibition may facilitate neuronal plasticity and promote motor learning in children. ?? 2010 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Gaetz", "given" : "W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "MacDonald", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cheyne", "given" : "D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Snead", "given" : "O. C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-3", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "792-807", "publisher" : "Elsevier Inc.", "title" : "Neuromagnetic imaging of movement-related cortical oscillations in children and adults: Age predicts post-movement beta rebound", "type" : "article-journal", "volume" : "51" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-4", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Cheyne et al., 2008; Crone et al., 1998; Gaetz et al., 2010; Muthukumaraswamy, 2010)", "plainTextFormattedCitation" : "(Cheyne et al., 2008; Crone et al., 1998; Gaetz et al., 2010; Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Cheyne et al., 2008; Crone et al., 1998; Gaetz et al., 2010; Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Cheyne et al., 2008; Crone et al., 1998; Gaetz et al., 2010; Muthukumaraswamy, 2010), and gaining a fuller understanding of the fundamental relationship of these signals to each other and also to human behaviour ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/nature04258", "ISBN" : "1476-4687 (Electronic)\\r0028-0836 (Linking)", "ISSN" : "1476-4687", "PMID" : "16372022", "abstract" : "Our capacity to process and respond behaviourally to multiple incoming stimuli is very limited. To optimize the use of this limited capacity, attentional mechanisms give priority to behaviourally relevant stimuli at the expense of irrelevant distractors. In visual areas, attended stimuli induce enhanced responses and an improved synchronization of rhythmic neuronal activity in the gamma frequency band (40-70 Hz). Both effects probably improve the neuronal signalling of attended stimuli within and among brain areas. Attention also results in improved behavioural performance and shortened reaction times. However, it is not known how reaction times are related to either response strength or gamma-band synchronization in visual areas. Here we show that behavioural response times to a stimulus change can be predicted specifically by the degree of gamma-band synchronization among those neurons in monkey visual area V4 that are activated by the behaviourally relevant stimulus. When there are two visual stimuli and monkeys have to detect a change in one stimulus while ignoring the other, their reactions are fastest when the relevant stimulus induces strong gamma-band synchronization before and after the change in stimulus. This enhanced gamma-band synchronization is also followed by shorter neuronal response latencies on the fast trials. Conversely, the monkeys' reactions are slowest when gamma-band synchronization is high in response to the irrelevant distractor. Thus, enhanced neuronal gamma-band synchronization and shortened neuronal response latencies to an attended stimulus seem to have direct effects on visually triggered behaviour, reflecting an early neuronal correlate of efficient visuo-motor integration.", "author" : [ { "dropping-particle" : "", "family" : "Womelsdorf", "given" : "Thilo", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mitra", "given" : "Partha P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Desimone", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature", "id" : "ITEM-1", "issue" : "7077", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "733-736", "title" : "Gamma-band synchronization in visual cortex predicts speed of change detection", "type" : "article-journal", "volume" : "439" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2010.03.041", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "20307670", "abstract" : "Groups of activated neurons typically synchronize in the gamma-frequency band (30-100. Hz), and gamma-band synchronization has been implicated in numerous cognitive functions. Those functions are ultimately expressed as behavior and therefore, functional gamma-band synchronization should be directly related to behavior. We recorded the magnetoencephalogram in human subjects and used a visual stimulus to induce occipital gamma-band activity. We found that the strength of this gamma-band activity at a given moment predicted the speed with which the subject was able to report a change in the stimulus. This predictive effect was restricted in time, frequency and space: It started only around 200. ms before the behaviorally relevant stimulus change, was present only between 50 and 80. Hz, and was significant only in bilateral middle occipital gyrus, while the peak of overall visually induced gamma-band activity was found in the calcarine sulcus. These results suggest that visually induced gamma-band activity is functionally relevant for the efficient transmission of stimulus change information to brain regions issuing the corresponding motor response. ?? 2010 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Hoogenboom", "given" : "Nienke", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schoffelen", "given" : "Jan Mathijs", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "1162-1167", "title" : "Visually induced gamma-band activity predicts speed of change detection in humans", "type" : "article-journal", "volume" : "51" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Hoogenboom et al., 2010; Womelsdorf et al., 2006)", "plainTextFormattedCitation" : "(Hoogenboom et al., 2010; Womelsdorf et al., 2006)", "previouslyFormattedCitation" : "(Hoogenboom et al., 2010; Womelsdorf et al., 2006)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Hoogenboom et al., 2010; Womelsdorf et al., 2006).However, few simultaneous EEG-fMRI studies have investigated gamma activity due to technical limitations as detailed below, and consequently the relationship between haemodynamic responses and the gamma band activity in humans remains incompletely understood ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/nature06976", "ISBN" : "0028-0836 1476-4687", "author" : [ { "dropping-particle" : "", "family" : "Logothetis", "given" : "Nikos K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature", "id" : "ITEM-1", "issue" : "7197", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "869-878", "title" : "What we can do and what we cannot do with fMRI", "type" : "article-journal", "volume" : "453" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Logothetis, 2008)", "plainTextFormattedCitation" : "(Logothetis, 2008)", "previouslyFormattedCitation" : "(Logothetis, 2008)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Logothetis, 2008). The recording of EEG data in the MRI environment is technically challenging primarily due to the effect of the MRI on the EEG data quality. Namely, EEG data are corrupted by the gradient artefact (GA) produced by the time-varying magnetic ?eld gradients needed for imaging, the pulse artefact produced by cardiac pulse driven motion in the strong magnetic ?eld of the MR scanner, and motion artefacts due to head movement in the MR environment ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Methods in molecular biology (Clifton, N.J.)", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "303-326", "title" : "Combining EEG and FMRI", "type" : "article-journal", "volume" : "711" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger and Bowtell, 2011)", "plainTextFormattedCitation" : "(Mullinger and Bowtell, 2011)", "previouslyFormattedCitation" : "(Mullinger and Bowtell, 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger and Bowtell, 2011). The frequency characteristics of these artefacts mean that the GA is the primary problem for studying gamma band activity, with residual GAs easily obscuring the small amplitude neuronal signal of interest even after correction ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "S1053-8119(10)01281-4 [pii] 10.1016/j.neuroimage.2010.09.079", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "20932913", "abstract" : "Large artefacts that compromise EEG data quality are generated when electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are carried out concurrently. The gradient artefact produced by the time-varying magnetic field gradients is the largest of these artefacts. Although average artefact correction (AAS) and related techniques can remove the majority of this artefact, the need to avoid amplifier saturation necessitates the use of a large dynamic range and strong low-pass filtering in EEG recording. Any intrinsic reduction in the gradient artefact amplitude would allow data with a higher bandwidth to be acquired without amplifier saturation, thus increasing the frequency range of neuronal activity that can be investigated using combined EEG-fMRI. Furthermore, gradient artefact correction methods assume a constant artefact morphology over time, so their performance is compromised by subject movement. Since the resulting, residual gradient artefacts can easily swamp signals from brain activity, any reduction in their amplitude would be highly advantageous for simultaneous EEG-fMRI studies. The aim of this work was to investigate whether adjustment of the subject's axial position in the MRI scanner can reduce the amplitude of the induced gradient artefact, before and after artefact correction using AAS. The variation in gradient artefact amplitude as a function of the subject's axial position was first investigated in six subjects by applying gradient pulses along the three Cartesian axes. The results of this study showed that a significant reduction in the gradient artefact magnitude can be achieved by shifting the subject axially by 4 cm towards the feet relative to the standard subject position (nasion at iso-centre). In a further study, the 4-cm shift was shown to produce a 40{%} reduction in the RMS amplitude (and a 31{%} reduction in the range) of the gradient artefact generated during the execution of a standard multi-slice, EPI sequence. By picking out signals occurring at harmonics of the slice acquisition frequency, it was also shown that the 4-cm shift led to a 36{%} reduction in the residual gradient artefact after AAS. Functional and anatomical MR data quality is not affected by the 4-cm shift, as the head remains in the homogeneous region of the static magnet field and gradients.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yan", "given" : "W X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2010/10/12", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "note" : "Mullinger, Karen J\nYan, Winston X\nBowtell, Richard\nG0901321(46386)/Medical Research Council/United Kingdom\nG9900259/Medical Research Council/United Kingdom\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2011 Feb 1;54(3):1942-50. Epub 2010 Oct 13.", "page" : "1942-1950", "title" : "Reducing the gradient artefact in simultaneous EEG-fMRI by adjusting the subject's axial position", "type" : "article-journal", "volume" : "54" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2011, 2008b)", "plainTextFormattedCitation" : "(Mullinger et al., 2011, 2008b)", "previouslyFormattedCitation" : "(Mullinger et al., 2011, 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2011, 2008b).Despite the technical challenges, a few studies have attempted to study the gamma band using concurrent EEG and fMRI measures ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.22545", "ISBN" : "1097-0193 (Electronic)\\r1065-9471 (Linking)", "ISSN" : "10970193", "PMID" : "24839083", "abstract" : "It remains an outstanding question whether gamma-band oscillations reflect unitary cognitive processes within the same task. EEG/MEG studies do lack the resolution or coverage to address the highly debated question whether single gamma activity patterns are linked with multiple cognitive modules or alternatively each pattern associates with a specific cognitive module, within the same coherent perceptual task. One way to disentangle these issues would be to provide direct identification of their sources, by combining different techniques. Here, we directly examined these questions by performing simultaneous EEG/fMRI using an ambiguous perception paradigm requiring holistic integration. We found that distinct gamma frequency sub-bands reflect different neural substrates and cognitive mechanisms when comparing object perception states vs. no categorical perception. A low gamma sub-band (near 40 Hz) activity was tightly related to the decision making network, and in particular the anterior insula. A high gamma sub-band (\u223c60 Hz) could be linked to early visual processing regions. The demonstration of a clear functional topography for distinct gamma sub-bands within the same task shows that distinct gamma-band modulations underlie sensory processing and perceptual decision mechanisms.", "author" : [ { "dropping-particle" : "", "family" : "Castelhano", "given" : "Jo\u00e3o", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Duarte", "given" : "Isabel Catarina", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wibral", "given" : "Michael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rodriguez", "given" : "Eug\u00e9nio", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Castelo-Branco", "given" : "Miguel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Human Brain Mapping", "id" : "ITEM-1", "issue" : "10", "issued" : { "date-parts" : [ [ "2014" ] ] }, "page" : "5219-5235", "title" : "The dual facet of gamma oscillations: Separate visual and decision making circuits as revealed by simultaneous EEG/fMRI", "type" : "article-journal", "volume" : "35" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1523/JNEUROSCI.0326-17.2017", "ISBN" : "9788578110796", "ISSN" : "0270-6474", "PMID" : "25246403", "abstract" : "applicability for this approach.", "author" : [ { "dropping-particle" : "", "family" : "Green", "given" : "Jessica J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Boehler", "given" : "Carsten N.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Roberts", "given" : "Kenneth C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Chen", "given" : "Ling-Chia", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Krebs", "given" : "Ruth M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Song", "given" : "Allen W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Woldorff", "given" : "Marty G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "The Journal of Neuroscience", "id" : "ITEM-2", "issue" : "33", "issued" : { "date-parts" : [ [ "2017" ] ] }, "page" : "7803-7810", "title" : "Cortical and Subcortical Coordination of Visual Spatial Attention Revealed by Simultaneous EEG\u2013fMRI Recording", "type" : "article-journal", "volume" : "37" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1093/schbul/sbv092", "ISBN" : "4940741059805", "ISSN" : "17451701", "PMID" : "26163477", "abstract" : "Objectives. Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). Methods. EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG- informed fMRI). Results. A gamma-band\u2013specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. Conclusions. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeat- edly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia.", "author" : [ { "dropping-particle" : "", "family" : "Leicht", "given" : "Gregor", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vauth", "given" : "Sebastian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Polomac", "given" : "Nenad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Andreou", "given" : "Christina", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rauh", "given" : "Jonas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mu??mann", "given" : "Marius", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karow", "given" : "Anne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mulert", "given" : "Christoph", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Schizophrenia Bulletin", "id" : "ITEM-3", "issue" : "1", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "239-249", "title" : "EEG-Informed fMRI Reveals a Disturbed Gamma-Band-Specific Network in Subjects at High Risk for Psychosis", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1073/pnas.0700668104", "ISBN" : "0027-8424 (Print) 0027-8424 (Linking)", "PMID" : "17670949", "abstract" : "Functional neuroimaging and electrophysiological studies have documented a dynamic baseline of intrinsic (not stimulus- or task-evoked) brain activity during resting wakefulness. This baseline is characterized by slow ({<}0.1 Hz) fluctuations of functional imaging signals that are topographically organized in discrete brain networks, and by much faster (1-80 Hz) electrical oscillations. To investigate the relationship between hemodynamic and electrical oscillations, we have adopted a completely data-driven approach that combines information from simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Using independent component analysis on the fMRI data, we identified six widely distributed resting state networks. The blood oxygenation level-dependent signal fluctuations associated with each network were correlated with the EEG power variations of delta, theta, alpha, beta, and gamma rhythms. Each functional network was characterized by a specific electrophysiological signature that involved the combination of different brain rhythms. Moreover, the joint EEG/fMRI analysis afforded a finer physiological fractionation of brain networks in the resting human brain. This result supports for the first time in humans the coalescence of several brain rhythms within large-scale brain networks as suggested by biophysical studies.", "author" : [ { "dropping-particle" : "", "family" : "Mantini", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Perrucci", "given" : "M G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gratta", "given" : "C", "non-dropping-particle" : "Del", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Romani", "given" : "G L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Corbetta", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "edition" : "2007/08/03", "id" : "ITEM-4", "issue" : "32", "issued" : { "date-parts" : [ [ "2007" ] ] }, "note" : "Mantini, D\nPerrucci, M G\nDel Gratta, C\nRomani, G L\nCorbetta, M\nNS48013/NS/NINDS NIH HHS/\nR01MH71920-06/MH/NIMH NIH HHS/\nProc Natl Acad Sci U S A. 2007 Aug 7;104(32):13170-5. Epub 2007 Aug 1.", "page" : "13170-13175", "title" : "Electrophysiological signatures of resting state networks in the human brain", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.1371/journal.pone.0010298", "ISBN" : "1932-6203 (Electronic)\\r1932-6203 (Linking)", "ISSN" : "19326203", "PMID" : "20421978", "abstract" : "EEG studies of working memory (WM) have demonstrated load dependent frequency band modulations. FMRI studies have localized load modulated activity to the dorsolateral prefrontal cortex (DLPFC), medial prefrontal cortex (MPFC), and posterior parietal cortex (PPC). Recently, an EEG-fMRI study found that low frequency band (theta and alpha) activity negatively correlated with the BOLD signal during the retention phase of a WM task. However, the coupling of higher (beta and gamma) frequencies with the BOLD signal during WM is unknown.", "author" : [ { "dropping-particle" : "", "family" : "Michels", "given" : "Lars", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bucher", "given" : "Kerstin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "L\u00fcchinger", "given" : "Rafael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Klaver", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Martin", "given" : "Ernst", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jeanmonod", "given" : "Daniel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brandeis", "given" : "Daniel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "PLoS ONE", "id" : "ITEM-5", "issue" : "4", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "1-15", "title" : "Simultaneous EEG-fMRI during a working memory task: Modulations in low and high frequency bands", "type" : "article-journal", "volume" : "5" }, "uris" : [ "" ] }, { "id" : "ITEM-6", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.10.058", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19878729", "abstract" : "Oscillations in the gamma-band frequency range have been described to be more closely connected to hemodynamic changes as assessed with functional magnetic resonance imaging (fMRI) than other aspects of neuronal activity. In addition, gamma-band oscillations have attracted much interest during the last few years since they are thought to play a crucial role in many aspects of brain function related to perception and cognition. It was the aim of the present simultaneous EEG-fMRI study to identify brain regions specifically involved in the generation of the auditory gamma-band response (GBR) using single-trial coupling of EEG and fMRI. Ten healthy subjects participated in this study. Three different runs of an auditory choice reaction task with increasing difficulty were performed. Brain activity was recorded simultaneously with high density EEG (61 channels) and fMRI (1.5 T). BOLD correlates of the GBR have been predicted using the single-trial amplitude of the GBR. Reaction times (p < 0.001), error rates (p < 0.05) and self-ratings of task difficulty and effort demands (p < 0.001) were related to the level of difficulty in the task. In addition, we found a significant influence of task difficulty on the amplitude of the GBR at Cz (p < 0.05). Using single-trial coupling of EEG and fMRI GBR-specific activations were found only in the auditory cortex, the thalamus and the anterior cingulate cortex (ACC) in the most difficult run. Single-trial coupling might be a useful method in order to increase our knowledge about the functional neuroanatomy of \"neural ensembles\" coupled by 40 Hz oscillations. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Mulert", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hepp", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirsch", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Reiser", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "J\u00e4ger", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moller", "given" : "H. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McCarley", "given" : "R. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-6", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2238-2247", "title" : "Single-trial coupling of the gamma-band response and the corresponding BOLD signal", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-7", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.09.011", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19778619", "abstract" : "Previous studies using combined electrical and hemodynamic measurements of brain activity, such as EEG and (BOLD) fMRI, have yielded discrepant results regarding the relationship between neuronal activity and the associated BOLD response. In particular, some studies suggest that this link, or transfer function, depends on the frequency content of neuronal activity, while others suggest that total neuronal power accounts for the changes in BOLD. Here we explored this dependency by comparing different frequency-dependent and -independent transfer functions, using simultaneous EEG-fMRI. Our results suggest that changes in BOLD are indeed associated with changes in the spectral profile of neuronal activity and that these changes do not arise from one specific spectral band. Instead they result from the dynamics of the various frequency components together, in particular, from the relative power between high and low frequencies. Understanding the nature of the link between neuronal activity and BOLD plays a crucial role in improving the interpretability of BOLD images as well as on the design of more robust and realistic models for the integration of EEG and fMRI.", "author" : [ { "dropping-particle" : "", "family" : "Rosa", "given" : "M J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kilner", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Blankenburg", "given" : "F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Josephs", "given" : "O", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Penny", "given" : "W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-7", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Rosa, M J\nKilner, J\nBlankenburg, F\nJosephs, O\nPenny, W\neng\nWellcome Trust/United Kingdom\nResearch Support, Non-U.S. Gov't\n2009/09/26 06:00\nNeuroimage. 2010 Jan 15;49(2):1496-509. doi: 10.1016/j.neuroimage.2009.09.011. Epub 2009 Sep 22.", "page" : "1496-1509", "title" : "Estimating the transfer function from neuronal activity to BOLD using simultaneous EEG-fMRI", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-8", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-8", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Castelhano et al., 2014; Green et al., 2017; Leicht et al., 2016; Mantini et al., 2007; Michels et al., 2010; Mulert et al., 2010; Rosa et al., 2010; Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Castelhano et al., 2014; Green et al., 2017; Leicht et al., 2016; Mantini et al., 2007; Michels et al., 2010; Mulert et al., 2010; Rosa et al., 2010; Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Castelhano et al., 2014; Green et al., 2017; Leicht et al., 2016; Mantini et al., 2007; Michels et al., 2010; Mulert et al., 2010; Rosa et al., 2010; Scheeringa et al., 2011). Of these a number limited the frequency range of the measured gamma band to a range of 30-50Hz (or narrower) to avoid the high frequencies where the GAs dominate (e.g. ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.09.011", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19778619", "abstract" : "Previous studies using combined electrical and hemodynamic measurements of brain activity, such as EEG and (BOLD) fMRI, have yielded discrepant results regarding the relationship between neuronal activity and the associated BOLD response. In particular, some studies suggest that this link, or transfer function, depends on the frequency content of neuronal activity, while others suggest that total neuronal power accounts for the changes in BOLD. Here we explored this dependency by comparing different frequency-dependent and -independent transfer functions, using simultaneous EEG-fMRI. Our results suggest that changes in BOLD are indeed associated with changes in the spectral profile of neuronal activity and that these changes do not arise from one specific spectral band. Instead they result from the dynamics of the various frequency components together, in particular, from the relative power between high and low frequencies. Understanding the nature of the link between neuronal activity and BOLD plays a crucial role in improving the interpretability of BOLD images as well as on the design of more robust and realistic models for the integration of EEG and fMRI.", "author" : [ { "dropping-particle" : "", "family" : "Rosa", "given" : "M J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kilner", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Blankenburg", "given" : "F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Josephs", "given" : "O", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Penny", "given" : "W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Rosa, M J\nKilner, J\nBlankenburg, F\nJosephs, O\nPenny, W\neng\nWellcome Trust/United Kingdom\nResearch Support, Non-U.S. Gov't\n2009/09/26 06:00\nNeuroimage. 2010 Jan 15;49(2):1496-509. doi: 10.1016/j.neuroimage.2009.09.011. Epub 2009 Sep 22.", "page" : "1496-1509", "title" : "Estimating the transfer function from neuronal activity to BOLD using simultaneous EEG-fMRI", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.10.058", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19878729", "abstract" : "Oscillations in the gamma-band frequency range have been described to be more closely connected to hemodynamic changes as assessed with functional magnetic resonance imaging (fMRI) than other aspects of neuronal activity. In addition, gamma-band oscillations have attracted much interest during the last few years since they are thought to play a crucial role in many aspects of brain function related to perception and cognition. It was the aim of the present simultaneous EEG-fMRI study to identify brain regions specifically involved in the generation of the auditory gamma-band response (GBR) using single-trial coupling of EEG and fMRI. Ten healthy subjects participated in this study. Three different runs of an auditory choice reaction task with increasing difficulty were performed. Brain activity was recorded simultaneously with high density EEG (61 channels) and fMRI (1.5 T). BOLD correlates of the GBR have been predicted using the single-trial amplitude of the GBR. Reaction times (p < 0.001), error rates (p < 0.05) and self-ratings of task difficulty and effort demands (p < 0.001) were related to the level of difficulty in the task. In addition, we found a significant influence of task difficulty on the amplitude of the GBR at Cz (p < 0.05). Using single-trial coupling of EEG and fMRI GBR-specific activations were found only in the auditory cortex, the thalamus and the anterior cingulate cortex (ACC) in the most difficult run. Single-trial coupling might be a useful method in order to increase our knowledge about the functional neuroanatomy of \"neural ensembles\" coupled by 40 Hz oscillations. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Mulert", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hepp", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirsch", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Reiser", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "J\u00e4ger", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moller", "given" : "H. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McCarley", "given" : "R. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2238-2247", "title" : "Single-trial coupling of the gamma-band response and the corresponding BOLD signal", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1073/pnas.0700668104", "ISBN" : "0027-8424 (Print) 0027-8424 (Linking)", "PMID" : "17670949", "abstract" : "Functional neuroimaging and electrophysiological studies have documented a dynamic baseline of intrinsic (not stimulus- or task-evoked) brain activity during resting wakefulness. This baseline is characterized by slow ({<}0.1 Hz) fluctuations of functional imaging signals that are topographically organized in discrete brain networks, and by much faster (1-80 Hz) electrical oscillations. To investigate the relationship between hemodynamic and electrical oscillations, we have adopted a completely data-driven approach that combines information from simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Using independent component analysis on the fMRI data, we identified six widely distributed resting state networks. The blood oxygenation level-dependent signal fluctuations associated with each network were correlated with the EEG power variations of delta, theta, alpha, beta, and gamma rhythms. Each functional network was characterized by a specific electrophysiological signature that involved the combination of different brain rhythms. Moreover, the joint EEG/fMRI analysis afforded a finer physiological fractionation of brain networks in the resting human brain. This result supports for the first time in humans the coalescence of several brain rhythms within large-scale brain networks as suggested by biophysical studies.", "author" : [ { "dropping-particle" : "", "family" : "Mantini", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Perrucci", "given" : "M G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gratta", "given" : "C", "non-dropping-particle" : "Del", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Romani", "given" : "G L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Corbetta", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "edition" : "2007/08/03", "id" : "ITEM-3", "issue" : "32", "issued" : { "date-parts" : [ [ "2007" ] ] }, "note" : "Mantini, D\nPerrucci, M G\nDel Gratta, C\nRomani, G L\nCorbetta, M\nNS48013/NS/NINDS NIH HHS/\nR01MH71920-06/MH/NIMH NIH HHS/\nProc Natl Acad Sci U S A. 2007 Aug 7;104(32):13170-5. Epub 2007 Aug 1.", "page" : "13170-13175", "title" : "Electrophysiological signatures of resting state networks in the human brain", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mantini et al., 2007; Mulert et al., 2010; Rosa et al., 2010)", "manualFormatting" : "Mantini et al., 2007; Mulert et al., 2010; Rosa et al., 2010", "plainTextFormattedCitation" : "(Mantini et al., 2007; Mulert et al., 2010; Rosa et al., 2010)", "previouslyFormattedCitation" : "(Mantini et al., 2007; Mulert et al., 2010; Rosa et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Mantini et al., 2007; Mulert et al., 2010; Rosa et al., 2010). However, this band limiting approach, is clearly suboptimal when gamma responses that are often reported in the upper portion of the 30-100 Hz frequency range ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Muthukumaraswamy, 2010)", "plainTextFormattedCitation" : "(Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Muthukumaraswamy, 2010) have been related to behaviour and other neuronal measures e.g. GABA concentration ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1073/pnas.0900728106", "abstract" : "Functional imaging of the human brain is an increasingly important technique for clinical and cognitive neuroscience research, with functional MRI (fMRI) of the blood oxygen level-dependent (BOLD) response and electroencephalography or magnetoencephalography (MEG) recordings of neural oscillations being 2 of the most popular approaches. However, the neural and physiological mechanisms that generate these responses are only partially understood and sources of interparticipant variability in these measures are rarely investigated. Here, we test the hypothesis that the properties of these neuroimaging metrics are related to individual levels of cortical inhibition by combining magnetic resonance spectroscopy to quantify resting GABA concentration in the visual cortex, MEG to measure stimulus-induced visual gamma oscillations and fMRI to measure the BOLD response to a simple visual grating stimulus. Our results demonstrate that across individuals gamma oscillation frequency is positively correlated with resting GABA concentration in visual cortex (R = 0.68; P {<} 0.02), BOLD magnitude is inversely correlated with resting GABA (R = -0.64; P {<} 0.05) and that gamma oscillation frequency is strongly inversely correlated with the magnitude of the BOLD response (R = -0.88; P {<} 0.001). Our results are therefore supportive of recent theories suggesting that these functional neuroimaging metrics are dependent on the excitation/inhibition balance in an individual's cortex and have important implications for the interpretation of functional imaging results, particularly when making between-group comparisons in clinical research.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Edden", "given" : "Richard A E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Derek K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Swettenham", "given" : "Jennifer B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Singh", "given" : "Krish D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "id" : "ITEM-1", "issue" : "20", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "8356-8361", "title" : "Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans", "type" : "article-journal", "volume" : "106" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Muthukumaraswamy et al., 2009)", "plainTextFormattedCitation" : "(Muthukumaraswamy et al., 2009)", "previouslyFormattedCitation" : "(Muthukumaraswamy et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Muthukumaraswamy et al., 2009). An alternative approach taken by other studies, or in addition to band-limiting gamma, has been to adopt a sparse fMRI sequence ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1093/schbul/sbv092", "ISBN" : "4940741059805", "ISSN" : "17451701", "PMID" : "26163477", "abstract" : "Objectives. Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). Methods. EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG- informed fMRI). Results. A gamma-band\u2013specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. Conclusions. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeat- edly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia.", "author" : [ { "dropping-particle" : "", "family" : "Leicht", "given" : "Gregor", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vauth", "given" : "Sebastian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Polomac", "given" : "Nenad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Andreou", "given" : "Christina", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rauh", "given" : "Jonas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mu??mann", "given" : "Marius", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karow", "given" : "Anne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mulert", "given" : "Christoph", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Schizophrenia Bulletin", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "239-249", "title" : "EEG-Informed fMRI Reveals a Disturbed Gamma-Band-Specific Network in Subjects at High Risk for Psychosis", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.10.058", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19878729", "abstract" : "Oscillations in the gamma-band frequency range have been described to be more closely connected to hemodynamic changes as assessed with functional magnetic resonance imaging (fMRI) than other aspects of neuronal activity. In addition, gamma-band oscillations have attracted much interest during the last few years since they are thought to play a crucial role in many aspects of brain function related to perception and cognition. It was the aim of the present simultaneous EEG-fMRI study to identify brain regions specifically involved in the generation of the auditory gamma-band response (GBR) using single-trial coupling of EEG and fMRI. Ten healthy subjects participated in this study. Three different runs of an auditory choice reaction task with increasing difficulty were performed. Brain activity was recorded simultaneously with high density EEG (61 channels) and fMRI (1.5 T). BOLD correlates of the GBR have been predicted using the single-trial amplitude of the GBR. Reaction times (p < 0.001), error rates (p < 0.05) and self-ratings of task difficulty and effort demands (p < 0.001) were related to the level of difficulty in the task. In addition, we found a significant influence of task difficulty on the amplitude of the GBR at Cz (p < 0.05). Using single-trial coupling of EEG and fMRI GBR-specific activations were found only in the auditory cortex, the thalamus and the anterior cingulate cortex (ACC) in the most difficult run. Single-trial coupling might be a useful method in order to increase our knowledge about the functional neuroanatomy of \"neural ensembles\" coupled by 40 Hz oscillations. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Mulert", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hepp", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirsch", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Reiser", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "J\u00e4ger", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moller", "given" : "H. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McCarley", "given" : "R. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2238-2247", "title" : "Single-trial coupling of the gamma-band response and the corresponding BOLD signal", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-3", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "previouslyFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011) rather than conventional, continuous fMRI acquisition. Sparse sequences feature an acquisition time shorter than the repetition time (TR) of the MRI sequence in order to provide a time window with no MRI gradients present in which to collect EEG data. As a result this approach enables the full gamma frequency range to be investigated. However, conventional MRI sequences require a long TR (>3s) and/or small number of slices to be acquired to provide the required sparsity; imposing limitations in the temporal sampling or spatial coverage possible and consequently limiting the utility of the fMRI data acquired.Therefore in order to optimize simultaneous EEG-fMRI recordings to study gamma-BOLD coupling, we need to establish a novel method to obtain cleaner EEG data in the high (>30Hz) frequency band. Multiband (MB) fMRI has the potential to overcome the limitations imposed by conventional sparse fMRI sequences. MB acquisition ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/mrm.22361", "ISBN" : "1522-2594 (Electronic) 0740-3194 (Linking)", "PMID" : "20432285", "abstract" : "Parallel imaging in the form of multiband radiofrequency excitation, together with reduced k-space coverage in the phase-encode direction, was applied to human gradient echo functional MRI at 7 T for increased volumetric coverage and concurrent high spatial and temporal resolution. Echo planar imaging with simultaneous acquisition of four coronal slices separated by 44mm and simultaneous 4-fold phase-encoding undersampling, resulting in 16-fold acceleration and up to 16-fold maximal aliasing, was investigated. Task/stimulus-induced signal changes and temporal signal behavior under basal conditions were comparable for multiband and standard single-band excitation and longer pulse repetition times. Robust, whole-brain functional mapping at 7 T, with 2 x 2 x 2mm(3) (pulse repetition time 1.25 sec) and 1 x 1 x 2mm(3) (pulse repetition time 1.5 sec) resolutions, covering fields of view of 256 x 256 x 176 mm(3) and 192 x 172 x 176 mm(3), respectively, was demonstrated with current gradient performance.", "author" : [ { "dropping-particle" : "", "family" : "Moeller", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Olman", "given" : "C A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Strupp", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Harel", "given" : "N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magn Reson Med", "edition" : "2010/05/01", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Moeller, Steen\nYacoub, Essa\nOlman, Cheryl A\nAuerbach, Edward\nStrupp, John\nHarel, Noam\nUgurbil, Kamil\nCA 76535/CA/NCI NIH HHS/\nEB 000513/EB/NIBIB NIH HHS/\nP30 NS057091/NS/NINDS NIH HHS/\nP30 NS057091-01/NS/NINDS NIH HHS/\nP30 NS057091-05/NS/NINDS NIH HHS/\nP41 RR008079/RR/NCRR NIH HHS/\nP41 RR008079-175232/RR/NCRR NIH HHS/\nP41 RR008079-17S17728/RR/NCRR NIH HHS/\nP41 RR08079/RR/NCRR NIH HHS/\nR01 CA076535/CA/NCI NIH HHS/\nR01 CA076535-03/CA/NCI NIH HHS/\nR01 EB000331/EB/NIBIB NIH HHS/\nR01 EB000331-08/EB/NIBIB NIH HHS/\nR01 EB008645/EB/NIBIB NIH HHS/\nR01 EB008645-03/EB/NIBIB NIH HHS/\nR01 EB008645-04/EB/NIBIB NIH HHS/\nR01 MH070800/MH/NIMH NIH HHS/\nR01 MH070800-05/MH/NIMH NIH HHS/\nR44 EB005139-03/EB/NIBIB NIH HHS/\nMagn Reson Med. 2010 May;63(5):1144-53. doi: 10.1002/mrm.22361.", "page" : "1144-1153", "title" : "Multiband multislice GE-EPI at 7 tesla, with 16-fold acceleration using partial parallel imaging with application to high spatial and temporal whole-brain fMRI", "type" : "article-journal", "volume" : "63" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1371/journal.pone.0015710", "ISBN" : "1932-6203 (Electronic) 1932-6203 (Linking)", "PMID" : "21187930", "abstract" : "Echo planar imaging (EPI) is an MRI technique of particular value to neuroscience, with its use for virtually all functional MRI (fMRI) and diffusion imaging of fiber connections in the human brain. EPI generates a single 2D image in a fraction of a second; however, it requires 2-3 seconds to acquire multi-slice whole brain coverage for fMRI and even longer for diffusion imaging. Here we report on a large reduction in EPI whole brain scan time at 3 and 7 Tesla, without significantly sacrificing spatial resolution, and while gaining functional sensitivity. The multiplexed-EPI (M-EPI) pulse sequence combines two forms of multiplexing: temporal multiplexing (m) utilizing simultaneous echo refocused (SIR) EPI and spatial multiplexing (n) with multibanded RF pulses (MB) to achieve mxn images in an EPI echo train instead of the normal single image. This resulted in an unprecedented reduction in EPI scan time for whole brain fMRI performed at 3 Tesla, permitting TRs of 400 ms and 800 ms compared to a more conventional 2.5 sec TR, and 2-4 times reductions in scan time for HARDI imaging of neuronal fibertracks. The simultaneous SE refocusing of SIR imaging at 7 Tesla advantageously reduced SAR by using fewer RF refocusing pulses and by shifting fat signal out of the image plane so that fat suppression pulses were not required. In preliminary studies of resting state functional networks identified through independent component analysis, the 6-fold higher sampling rate increased the peak functional sensitivity by 60{%}. The novel M-EPI pulse sequence resulted in a significantly increased temporal resolution for whole brain fMRI, and as such, this new methodology can be used for studying non-stationarity in networks and generally for expanding and enriching the functional information.", "author" : [ { "dropping-particle" : "", "family" : "Feinberg", "given" : "D A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "S M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ramanna", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gunther", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Glasser", "given" : "M F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "PLoS One", "edition" : "2010/12/29", "id" : "ITEM-2", "issue" : "12", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Feinberg, David A\nMoeller, Steen\nSmith, Stephen M\nAuerbach, Edward\nRamanna, Sudhir\nGunther, Matthias\nGlasser, Matt F\nMiller, Karla L\nUgurbil, Kamil\nYacoub, Essa\n1R44NS063537/NS/NINDS NIH HHS/\n1R44NS073417/NS/NINDS NIH HHS/\n1U54MH091657-01/MH/NIMH NIH HHS/\nP30 NS057091/NS/NINDS NIH HHS/\nP41 RR08079/RR/NCRR NIH HHS/\nR01 EB000331/EB/NIBIB NIH HHS/\nS10 RR1395/RR/NCRR NIH HHS/\nPLoS One. 2010 Dec 20;5(12):e15710. doi: 10.1371/journal.pone.0015710.", "page" : "e15710", "title" : "Multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging", "type" : "article-journal", "volume" : "5" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Feinberg et al., 2010; Moeller et al., 2010)", "plainTextFormattedCitation" : "(Feinberg et al., 2010; Moeller et al., 2010)", "previouslyFormattedCitation" : "(Feinberg et al., 2010; Moeller et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Feinberg et al., 2010; Moeller et al., 2010) can be employed to: shorten repetition times (TR); increase brain coverage for a given TR; or shorten the acquisition time of whole-head fMRI in a sparse fMRI sequence which would lengthen the gradient-free time window in which EEG data can be collected. Sparse MB fMRI acquisitions therefore offer great potential for improving EEG data quality during simultaneous acquisitions. However, due to the additional radio frequency (RF) power of MB excitation the safety of EEG-MB fMRI acquisitions must be assessed ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/mrm.24719", "ISBN" : "1522-2594 (Electronic) 0740-3194 (Linking)", "PMID" : "23468087", "abstract" : "PURPOSE: To evaluate an alternative method for generating multibanded radiofrequency (RF) pulses for use in multiband slice-accelerated imaging with slice-GRAPPA unaliasing, substantially reducing the required peak power without bandwidth compromises. This allows much higher accelerations for spin-echo methods such as SE-fMRI and diffusion-weighted MRI where multibanded slice acceleration has been limited by available peak power. THEORY AND METHODS: Multibanded \"time-shifted\" RF pulses were generated by inserting temporal shifts between the applications of RF energy for individual bands, avoiding worst-case constructive interferences. Slice profiles and images in phantoms and human subjects were acquired at 3 T. RESULTS: For typical sinc pulses, time-shifted multibanded RF pulses were generated with little increase in required peak power compared to single-banded pulses. Slice profile quality was improved by allowing for higher pulse bandwidths, and image quality was improved by allowing for optimum flip angles to be achieved. CONCLUSION: A simple approach has been demonstrated that significantly alleviates the restrictions imposed on achievable slice acceleration factors in multiband spin-echo imaging due to the power requirements of multibanded RF pulses. This solution will allow for increased accelerations in diffusion-weighted MRI applications where data acquisition times are normally very long and the ability to accelerate is extremely valuable.", "author" : [ { "dropping-particle" : "", "family" : "Auerbach", "given" : "E J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Xu", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magn Reson Med", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2013" ] ] }, "note" : "Auerbach, Edward J\nXu, Junqian\nYacoub, Essa\nMoeller, Steen\nUgurbil, Kamil\nENG\nP41 EB015894/EB/NIBIB NIH HHS/\nP41 RR008079/RR/NCRR NIH HHS/\nU54 MH091657/MH/NIMH NIH HHS/\n1U54MH091657/MH/NIMH NIH HHS/\nResearch Support, N.I.H., Extramural\n2013/03/08 06:00\nMagn Reson Med. 2013 May;69(5):1261-7. doi: 10.1002/mrm.24719. Epub 2013 Mar 6.", "page" : "1261-1267", "title" : "Multiband accelerated spin-echo echo planar imaging with reduced peak RF power using time-shifted RF pulses", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Auerbach et al., 2013)", "plainTextFormattedCitation" : "(Auerbach et al., 2013)", "previouslyFormattedCitation" : "(Auerbach et al., 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Auerbach et al., 2013). In addition, as MB methods can affect temporal signal to noise (tSNR) of fMRI data ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2014.10.027", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "ISSN" : "10959572", "PMID" : "25462696", "abstract" : "Echo planar imaging (EPI) is the MRI technique that is most widely used for blood oxygen level-dependent (BOLD) functional MRI (fMRI). Recent advances in EPI speed have been made possible with simultaneous multi-slice (SMS) methods which combine acceleration factors M from multiband (MB) radiofrequency pulses and S from simultaneous image refocusing (SIR) to acquire a total of N = S\u00d7. M images in one echo train, providing up to N times speed-up in total acquisition time over conventional EPI. We evaluated accelerations as high as N = 48 using different combinations of S and M which allow for whole brain imaging in as little as 100. ms at 3. T with a 32 channel head coil. The various combinations of acceleration parameters were evaluated by tSNR as well as BOLD contrast-to-noise ratio (CNR) and information content from checkerboard and movie clips in fMRI experiments. We found that at low acceleration factors (N. \u2264. 6), setting S=. 1 and varying M alone yielded the best results in all evaluation metrics, while at acceleration N = 8 the results were mixed using both S=. 1 and S=. 2 sequences. At higher acceleration factors (N > 8), using S=. 2 yielded maximal BOLD CNR and information content as measured by classification of movie clip frames. Importantly, we found significantly greater BOLD information content using relatively fast TRs in the range of 300. ms-600. ms compared to a TR of 2. s, suggesting that faster TRs capture more information per unit time in task based fMRI.", "author" : [ { "dropping-particle" : "", "family" : "Chen", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vu", "given" : "A. T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Xu", "given" : "J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Feinberg", "given" : "D. A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "452-459", "title" : "Evaluation of highly accelerated simultaneous multi-slice EPI for fMRI", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2015.08.056", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "ISSN" : "10959572", "PMID" : "26341029", "abstract" : "Functional magnetic resonance imaging (fMRI) studies that require high-resolution whole-brain coverage have long scan times that are primarily driven by the large number of thin slices acquired. Two-dimensional multiband echo-planar imaging (EPI) sequences accelerate the data acquisition along the slice direction and therefore represent an attractive approach to such studies by improving the temporal resolution without sacrificing spatial resolution. In this work, a 2D multiband EPI sequence was optimized for 1.5. mm isotropic whole-brain acquisitions at 3. T with 10 healthy volunteers imaged while performing simultaneous visual and motor tasks. The performance of the sequence was evaluated in terms of BOLD sensitivity and false-positive activation at multiband (MB) factors of 1, 2, 4, and 6, combined with in-plane GRAPPA acceleration of 2. \u00d7 (GRAPPA 2), and the two reconstruction approaches of Slice-GRAPPA and Split Slice-GRAPPA. Sensitivity results demonstrate significant gains in temporal signal-to-noise ratio (tSNR) and t-score statistics for MB 2, 4, and 6 compared to MB 1. The MB factor for optimal sensitivity varied depending on anatomical location and reconstruction method. When using Slice-GRAPPA reconstruction, evidence of false-positive activation due to signal leakage between simultaneously excited slices was seen in one instance, 35 instances, and 70 instances over the ten volunteers for the respective accelerations of MB 2. \u00d7. GRAPPA 2, MB 4. \u00d7. GRAPPA 2, and MB 6. \u00d7. GRAPPA 2. The use of Split Slice-GRAPPA reconstruction suppressed the prevalence of false positives significantly, to 1 instance, 5 instances, and 5 instances for the same respective acceleration factors. Imaging protocols using an acceleration factor of MB 2. \u00d7. GRAPPA 2 can be confidently used for high-resolution whole-brain imaging to improve BOLD sensitivity with very low probability for false-positive activation due to slice leakage. Imaging protocols using higher acceleration factors (MB 3 or MB 4. \u00d7. GRAPPA 2) can likely provide even greater gains in sensitivity but should be carefully optimized to minimize the possibility of false activations.", "author" : [ { "dropping-particle" : "", "family" : "Todd", "given" : "Nick", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "Steen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "Edward J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "Essa", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Flandin", "given" : "Guillaume", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Weiskopf", "given" : "Nikolaus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "32-42", "title" : "Evaluation of 2D multiband EPI imaging for high-resolution, whole-brain, task-based fMRI studies at 3T: Sensitivity and slice leakage artifacts", "type" : "article-journal", "volume" : "124" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Chen et al., 2015; Todd et al., 2016)", "plainTextFormattedCitation" : "(Chen et al., 2015; Todd et al., 2016)", "previouslyFormattedCitation" : "(Chen et al., 2015; Todd et al., 2016)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Chen et al., 2015; Todd et al., 2016) assessing the implementation of MB and the effect on fMRI tSNR is also important to enable optimised EEG-fMRI studies to take place.Therefore the aim of this work was to assess the overall feasibility of recording EEG simultaneously with MB fMRI in humans. This took place in three parts: i) assessing the safety implications of EEG-MB fMRI; ii) assessing the tSNR of MB fMRI and iii) applying an optimised EEG-MB fMRI approach to investigate single-trial coupling relationships between MB-BOLD and gamma and beta frequency EEG responses to a finger-abduction motor task. We chose to investigate motor responses as an event-related synchronisation (ERS) of gamma oscillations (reflecting an increase in power), typically accompanied by desynchronization (ERD) of beta frequency (15-30Hz) oscillations (reflecting a reduction in power), in the primary motor cortex contralateral to the movement have been well documented using invasive electroencephalography (ECoG) ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.08.041", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19715762", "abstract" : "High gamma (HG) power changes during motor activity, especially at frequencies above 70\u00a0Hz, play an important role in functional cortical mapping and as control signals for BCI (brain-computer interface) applications. Most studies of HG activity have used ECoG (electrocorticography) which provides high-quality spatially localized signals, but is an invasive method. Recent studies have shown that non-invasive modalities such as EEG and MEG can also detect task-related HG power changes. We show here that a 27 channel EEG (electroencephalography) montage provides high-quality spatially localized signals non-invasively for HG frequencies ranging from 83 to 101\u00a0Hz. We used a generic head model, a weighted minimum norm least squares (MNLS) inverse method, and a self-paced finger movement paradigm. The use of an inverse method enables us to map the EEG onto a generic cortex model. We find the HG activity during the task to be well localized in the contralateral motor area. We find HG power increases prior to finger movement, with average latencies of 462\u00a0ms and 82\u00a0ms before EMG (electromyogram) onset. We also find significant phase-locking between contra- and ipsilateral motor areas over a similar HG frequency range; here the synchronization onset precedes the EMG by 400\u00a0ms. We also compare our results to ECoG data from a similar paradigm and find EEG mapping and ECoG in good agreement. Our findings demonstrate that mapped EEG provides information on two important parameters for functional mapping and BCI which are usually only found in HG of ECoG signals: spatially localized power increases and bihemispheric phase-locking. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Scherer", "given" : "R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sorensen", "given" : "L. B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "930-938", "publisher" : "Elsevier Inc.", "title" : "High gamma mapping using EEG", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Darvas et al., 2010)", "plainTextFormattedCitation" : "(Darvas et al., 2010)", "previouslyFormattedCitation" : "(Darvas et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Darvas et al., 2010), MEG ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Muthukumaraswamy, 2010)", "plainTextFormattedCitation" : "(Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Muthukumaraswamy, 2010) and EEG ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.04.178", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18511304", "abstract" : "There has been increasing interest in the functional role of high-frequency (> 30??Hz) cortical oscillations accompanying various sensorimotor and cognitive tasks in humans. Similar \"high gamma\" activity has been observed in the motor cortex, although the role of this activity in motor control is unknown. Using whole-head MEG recordings combined with advanced source localization methods, we identified high-frequency (65 to 80??Hz) gamma oscillations in the primary motor cortex during self-paced movements of the upper and lower limbs. Brief bursts of gamma activity were localized to the contralateral precentral gyrus (MI) during self-paced index finger abductions, elbow flexions and foot dorsiflexions. In comparison to lower frequency (10-30??Hz) sensorimotor rhythms that are bilaterally suppressed prior to and during movement (Jurkiewicz et al., 2006), high gamma activity increased only during movement, reaching maximal increase 100 to 250??ms following EMG onset, and was lateralized to contralateral MI, similar to findings from intracranial EEG studies. Peak frequency of gamma activity was significantly lower during foot dorsiflexion (67.4 ?? 5.2??Hz) than during finger abduction (75.3 ?? 4.4??Hz) and elbow flexion (73.9 ?? 3.7??Hz) although markedly similar for left and right movements of the same body part within subjects, suggesting activation of a common underlying network for gamma oscillations in the left and right motor cortex. These findings demonstrate that voluntary movements elicit high-frequency gamma oscillations in the primary motor cortex that are effector specific, and possibly reflect the activation of cortico-subcortical networks involved in the feedback control of discrete movements. ?? 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bells", "given" : "Sonya", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaetz", "given" : "William", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bostan", "given" : "Andreea C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "332-342", "title" : "Self-paced movements induce high-frequency gamma oscillations in primary motor cortex", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Cheyne et al., 2008)", "plainTextFormattedCitation" : "(Cheyne et al., 2008)", "previouslyFormattedCitation" : "(Cheyne et al., 2008)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Cheyne et al., 2008) (for reviews, ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.3389/fnhum.2013.00138", "ISBN" : "1662-5161 (Electronic)\\n1662-5161 (Linking)", "ISSN" : "1662-5161", "PMID" : "23596409", "abstract" : "In recent years high-frequency brain activity in the gamma-frequency band (30-80 Hz) and above has become the focus of a growing body of work in MEG/EEG research. Unfortunately, high-frequency neural activity overlaps entirely with the spectral bandwidth of muscle activity (~20-300 Hz). It is becoming appreciated that artifacts of muscle activity may contaminate a number of non-invasive reports of high-frequency activity. In this review, the spectral, spatial, and temporal characteristics of muscle artifacts are compared with those described (so far) for high-frequency neural activity. In addition, several of the techniques that are being developed to help suppress muscle artifacts in MEG/EEG are reviewed. Suggestions are made for the collection, analysis, and presentation of experimental data with the aim of reducing the number of publications in the future that may contain muscle artifacts.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Frontiers in Human Neuroscience", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1-11", "title" : "High-frequency brain activity and muscle artifacts in MEG/EEG: a review and recommendations", "type" : "article-journal", "volume" : "7" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.3389/fnhum.2013.00575", "ISBN" : "1662-5161 (Electronic)\\r1662-5161 (Linking)", "ISSN" : "1662-5161", "PMID" : "24062675", "abstract" : "The human motor cortex exhibits transient bursts of high frequency gamma oscillations in the 60 to 90 Hz range during movement. It has been proposed that gamma oscillations generally reflect local intracortical activity. However, movement-evoked gamma is observed simultaneously in both cortical and subcortical (basal ganglia) structures and thus appears to reflect long-range cortical-subcortical interactions. Recent evidence suggests that gamma oscillations do not simply reflect sensory reafference, but have a facilitative role in movement initiation. Here we summarize contributions of MEG to our understanding of movement-evoked gamma oscillations, including evidence that transient gamma bursts during the performance of specific movements constitutes a stereotyped spectral and temporal pattern within individuals \u2013 a gamma \u201cfingerprint\u201d \u2013 that is highly stable over time. Although their functional significance remains to be fully understood, movement-evoked gamma oscillations may represent frequency specific tuning within cortical-subcortical networks that can be monitored non-invasively using MEG during a variety of motor tasks, and may provide important information regarding cortical dynamics of ongoing motor control.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Frontiers in Human Neuroscience", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1-7", "title" : "MEG studies of motor cortex gamma oscillations: evidence for a gamma \u201cfingerprint\u201d in the brain?", "type" : "article-journal", "volume" : "7" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.expneurol.2012.08.030", "ISBN" : "1090-2430 (Electronic)\\n0014-4886 (Linking)", "ISSN" : "00144886", "PMID" : "22981841", "abstract" : "The human sensorimotor cortex demonstrates a variety of oscillatory activity that is strongly modulated by movement and somatosensory input. Studies using scalp EEG and intracranial electrical recordings have provided much of our current knowledge regarding the frequency and temporal specificity of these sensorimotor rhythms and their relationship to various movement parameters, however with limitations in identifying the underlying neural sources, and the variety of motor behaviors that can be studied, respectively. Magnetoencephalography (MEG) recordings, combined with spatial filtering source reconstruction methods, provide an ideal non-invasive method for the localization of sensorimotor rhythms and for describing their precise time course during a variety of motor tasks. This review describes the application of MEG to the study of oscillatory activity in the human sensorimotor cortex, including advances in localization techniques and recent contributions of MEG to our understanding of the functional role of these oscillations in both adult and developmental populations. \u00a9 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas Owen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Experimental Neurology", "id" : "ITEM-3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "27-39", "title" : "MEG studies of sensorimotor rhythms: A review", "type" : "article", "volume" : "245" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)", "manualFormatting" : "Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013", "plainTextFormattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)", "previouslyFormattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013). To our knowledge, the motor gamma-BOLD relationship has not previously been investigated with simultaneous EEG-fMRI acquisition in humans. Therefore, through this proof of concept study we also aim to widen the understanding of gamma-BOLD coupling across the cortex. We hypothesise that the single-trial positive BOLD response in contralateral motor cortex will correlate positively with gamma power ERS and negatively with beta power ERD. Methods Data were acquired and analysed in two stages. Stage one consisted of initial safety testing and image-quality optimisation of EEG-MB fMRI; whilst stage two involved the application of the optimised scanning protocol for the concurrent EEG-fMRI study of human brain responses during motor tasks. During both stages, EEG data were acquired using BrainAmp MRplus EEG amplifiers (Brain Products, Munich) with 5kHz sampling rate and an MR-compatible 63-channel EEG cap (EasyCap, Herrsching). The hardware band-pass filters were set to a 0.016-250 Hz range, with a roll-off of 30 dB/octave at high frequency. Electrode layout followed the extended international 10-20 system with an additional channel for recording the electrocardiogram (ECG). FCz was used as the reference electrode. A 3T Philips Achieva MRI scanner with a body transmit and 32-channel receiver-array head coil was used for MR data acquisition. The MB implementation for fMRI acquisitions in this study was from Gyrotools, Zurich. MR-EEG scanner clocks were synchronised for all EEG data acquisition ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2008b)", "plainTextFormattedCitation" : "(Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2008b). All data acquisition on humans was performed with approval from the local ethics committee and informed consent was obtained from all subjects involved in this project.Stage 1: Assessing the safety and tSNR of EEG-MB fMRISafety testingSafety testing was performed on a conductive, head shaped phantom with a conductivity of about 0.5?-1m-1 to mimic skin conductivity ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.20891", "abstract" : "The collection of electroencephalography (EEG) data during simultaneous functional magnetic resonance imaging (fMRI) is impeded by large artefacts in the EEG recordings, with the pulse artefact (PA) being particularly challenging because of its persistence even after application of artefact correction algorithms. Despite several possible causes of the PA having been hypothesized, few studies have rigorously quantified the contributions from the different putative sources. This article presents analytic expressions and simulations describing two possible sources of the PA corresponding to different movements in the strong static field of the MR scanner: cardiac-pulse-driven head rotation and blood-flow-induced Hall voltages. Models of head rotation about a left-right axis and flow in a deep artery running in the anterior-posterior direction reproduced properties of the PA including the left/right spatial variation of polarity. Of these two sources, head rotation was shown to be the most likely source of the PA with simulated magnitudes of {>}200 muV being generated at 3 T, similar to the in vivo PA magnitudes, for an angular velocity of just 0.5 degrees /s. Smaller artefact voltages of less than 10 muV were calculated for flow in a model artery with physical characteristics similar to the internal carotid artery. A deeper physical understanding of the PA is a key step in working toward production of higher fidelity EEG/fMRI data: analytic expressions for the artefact voltages can guide a redesign of the wiring layout on EEG caps to minimize intrinsic artefact pickup, while simulated artefact maps could be incorporated into selective filters.", "author" : [ { "dropping-particle" : "", "family" : "Yan", "given" : "Winston X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Geirsdottir", "given" : "Gerda B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Hum Brain Mapp", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "604-620", "title" : "Physical modeling of pulse artefact sources in simultaneous EEG/fMRI", "type" : "article-journal", "volume" : "31" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Yan et al., 2010)", "plainTextFormattedCitation" : "(Yan et al., 2010)", "previouslyFormattedCitation" : "(Yan et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Yan et al., 2010). The phantom was left in the scanner room over night to equilibrate to the ambient temperature. The EEG cap was then connected to the phantom using conductive gel (Abralyte 2000 [EasyCap GmbH, Munich]) and all electrode impedances were maintained below 15k?. Fibre-optic thermometers (Luxtron Corporation, Santa Clara, CA, USA) were used to continually monitor (1 Hz sampling rate) heating effects at seven locations: four scalp electrodes (Cz, TP7, FCz & TP8), the ECG lead (connected to the base of the phantom’s neck), the cable bundle coming from the EEG cap and the scanner bore (as a control measurement of heating effects unrelated to the presence of the EEG system). Thermometer sensors were placed in the conductive gel under the electrodes and taped to the surface of the cable bundle and scanner bore. The phantom was then placed at the MR scanner iso-centre. Firstly, a 5-minute recording of baseline temperature at each location was collected without any scanning. Then two 20-minute MRI scans, both employing MB factor 4 and spectral presaturation with inversion recovery (SPIR) fat suppression, were performed to test for heating during the highest realistic values of specific absorption rate (SAR) for a given sequence type. Please note MB factor 4 was the highest available in this implementation of MB. The sequences tested were: 1) gradient echo (GE)-EPI (using: TR/TE=1000/40ms, SENSE=2, slices=48, B1 RMS=1.09μT, SAR/head=22%); 2) Pseudo-continuous arterial spin labelling (PCASL)-GE-EPI (using: TR/TE=3500/9.8ms, SENSE=2, slices=32, B1 RMS=1.58μT, SAR/head=46%). Between the two MRI scans there was a 10 minute period without scanning to allow a return to baseline following any heating effects from the previous MRI scan.AnalysisThe mean baseline temperature at each thermometer location was determined using the 5 minute recording prior to each MRI scan. For each location, the mean baseline temperature was then subtracted from the temperature timeseries recorded during each scan to give the change in temperature across the whole 20 minute scan period.Image quality: tSNRTo assess the effect of the implementation of MB excitation on the fMRI signal tSNR, fMRI data were recorded on 3 healthy-adult subjects (age 32 ± 2 years) during five different GE-EPI pulse sequences: MB factor = 1 with equidistant slice acquisition MB factor = 2 with equidistant slice acquisition MB factor = 2 with sparse slice acquisition MB factor = 3 with equidistant slice acquisition MB factor = 3 with sparse slice acquisitionEquidistant acquisition used the full TR period, comprised of equal temporal intervals between each slice acquisition. For sparse acquisitions MR data were acquired in the minimum possible time at the beginning of the TR period; the rest of the TR period then formed a quiet period with no MR gradients. A TR = 3060ms and 36 slices were chosen to ensure that these parameters could be used for all combinations of MB factors and slice acquisition (in scans i-v) whilst adhering to requirements for EEG clock synchronisation ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2006.04.231", "abstract" : "Investigating human brain function non-invasively by simultaneous EEG and fMRI measurements is gaining in popularity as more and better solutions to the inherent technical challenges emerge. We demonstrate the use of a commercially available frequency divider and phase-locking device for the purpose of synchronizing an MRI acquisition with a simultaneous recording of the EEG. Synchronization hugely improves the effectiveness of MRI artefact removal from the EEG signal by the common mean template subtraction method. It complements or substitutes post-processing techniques like filtering, thereby increasing the usable bandwidth of the EEG signal to about 150 Hz. This is important for covering the full range of human Gamma band activity. Similarly, synchronization eliminates the necessity for over-sampling of the EEG signal.", "author" : [ { "dropping-particle" : "", "family" : "Mandelkow", "given" : "H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Halder", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Boesiger", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brandeis", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "1120-1126", "title" : "Synchronization facilitates removal of MRI artefacts from concurrent EEG recordings and increases usable bandwidth", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "plainTextFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mandelkow et al., 2006; Mullinger et al., 2008b). Other parameters were set for all scans as follows: TE= 40ms, SENSE=2, flip angle=79°, 41 volumes acquired. A T1-weighted anatomical image was also acquired for each subject.AnalysisFor each subject the anatomical image was used to segment the grey matter (FSL FAST, ) ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1109/42.906424", "ISBN" : "0278-0062 (Print) 0278-0062 (Linking)", "PMID" : "11293691", "abstract" : "The finite mixture (FM) model is the most commonly used model for statistical segmentation of brain magnetic resonance (MR) images because of its simple mathematical form and the piecewise constant nature of ideal brain MR images. However, being a histogram-based model, the FM has an intrinsic limitation--no spatial information is taken into account. This causes the FM model to work only on well-defined images with low levels of noise; unfortunately, this is often not the the case due to artifacts such as partial volume effect and bias field distortion. Under these conditions, FM model-based methods produce unreliable results. In this paper, we propose a novel hidden Markov random field (HMRF) model, which is a stochastic process generated by a MRF whose state sequence cannot be observed directly but which can be indirectly estimated through observations. Mathematically, it can be shown that the FM model is a degenerate version of the HMRF model. The advantage of the HMRF model derives from the way in which the spatial information is encoded through the mutual influences of neighboring sites. Although MRF modeling has been employed in MR image segmentation by other researchers, most reported methods are limited to using MRF as a general prior in an FM model-based approach. To fit the HMRF model, an EM algorithm is used. We show that by incorporating both the HMRF model and the EM algorithm into a HMRF-EM framework, an accurate and robust segmentation can be achieved. More importantly, the HMRF-EM framework can easily be combined with other techniques. As an example, we show how the bias field correction algorithm of Guillemaud and Brady (1997) can be incorporated into this framework to achieve a three-dimensional fully automated approach for brain MR image segmentation.", "author" : [ { "dropping-particle" : "", "family" : "Zhang", "given" : "Y", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brady", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "IEEE Trans Med Imaging", "edition" : "2001/04/11", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2001" ] ] }, "note" : "Zhang, Y\nBrady, M\nSmith, S\nIEEE Trans Med Imaging. 2001 Jan;20(1):45-57.", "page" : "45-57", "title" : "Segmentation of brain MR images through a hidden Markov random field model and the expectation-maximization algorithm", "type" : "article-journal", "volume" : "20" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Zhang et al., 2001)", "plainTextFormattedCitation" : "(Zhang et al., 2001)", "previouslyFormattedCitation" : "(Zhang et al., 2001)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Zhang et al., 2001) which formed a mask for subsequent analysis. The tSNR was calculated in every grey matter voxel (Eq. 1) and then averaged over voxels for each subject. The group mean and standard deviation in grey matter of the tSNR was then found for each of the five scans to assess the change in tSNR with MB factor and slice acquisition scheme. tSNRvoxel=?mean?signal?over?timevoxelstandard?deviation?over?timevoxelEq. 1Stage 2: EEG-fMRI motor study12 right-handed subjects (10 males, 2 females, age = 26.6 ±5.7) took part in the study. After initial data processing, two subjects were excluded from further analysis due to repeated, excessive head motion (>4mm, as assessed from fMRI realignment parameters).Data acquisitionThe EEG cap was put on the subject and all electrode impedances were maintained below 10k? for the duration of the study. EEG-fMRI data were acquired using a sparse GE-EPI scheme (TR=3000ms (of which: acquisition time=750ms, quiet period=2250ms), TE=40ms, MB factor=3, 33 slices, voxels=3mm3, SENSE = 2, FOV = 240 x 240 mm, flip angle = 79°, 192 volumes, SAR/head<7%). These parameters had been optimised based on the results of Stage 1 and the requirements of the paradigm (see below). High frequency (>30 Hz) artefacts were minimised by mechanically isolating the EEG amplifiers from the scanner bed and minimising MR scanner room environment noise ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Methods in molecular biology (Clifton, N.J.)", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "303-326", "title" : "Combining EEG and FMRI", "type" : "article-journal", "volume" : "711" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1073/pnas.1221287110", "ISBN" : "1091-6490 (Electronic) 0027-8424 (Linking)", "PMID" : "23898206", "abstract" : "fMRI is the foremost technique for noninvasive measurement of human brain function. However, its utility is limited by an incomplete understanding of the relationship between neuronal activity and the hemodynamic response. Though the primary peak of the hemodynamic response is modulated by neuronal activity, the origin of the typically negative poststimulus signal is poorly understood and its amplitude assumed to covary with the primary response. We use simultaneous recordings of EEG with blood oxygenation level-dependent (BOLD) and cerebral blood flow (CBF) fMRI during unilateral median nerve stimulation to show that the poststimulus fMRI signal is neuronally modulated. We observe high spatial agreement between concurrent BOLD and CBF responses to median nerve stimulation, with primary signal increases in contralateral sensorimotor cortex and primary signal decreases in ipsilateral sensorimotor cortex. During the poststimulus period, the amplitude and directionality (positive/negative) of the BOLD signal in both contralateral and ipsilateral sensorimotor cortex depends on the poststimulus synchrony of 8-13 Hz EEG neuronal activity, which is often considered to reflect cortical inhibition, along with concordant changes in CBF and metabolism. Therefore we present conclusive evidence that the fMRI time course represents a hemodynamic signature of at least two distinct temporal phases of neuronal activity, substantially improving understanding of the origin of the BOLD response and increasing the potential measurements of brain function provided by fMRI. We suggest that the poststimulus EEG and fMRI responses may be required for the resetting of the entire sensory network to enable a return to resting-state activity levels.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mayhew", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bagshaw", "given" : "A P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Francis", "given" : "S T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proc Natl Acad Sci U S A", "edition" : "2013/07/31", "id" : "ITEM-2", "issue" : "33", "issued" : { "date-parts" : [ [ "2013" ] ] }, "note" : "Mullinger, Karen J\nMayhew, Stephen D\nBagshaw, Andrew P\nBowtell, Richard\nFrancis, Susan T\nG0901321/Medical Research Council/United Kingdom\nProc Natl Acad Sci U S A. 2013 Aug 13;110(33):13636-41. doi: 10.1073/pnas.1221287110. Epub 2013 Jul 29.", "page" : "13636-13641", "title" : "Poststimulus undershoots in cerebral blood flow and BOLD fMRI responses are modulated by poststimulus neuronal activity", "type" : "article-journal", "volume" : "110" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2013; Mullinger and Bowtell, 2011)", "plainTextFormattedCitation" : "(Mullinger et al., 2013; Mullinger and Bowtell, 2011)", "previouslyFormattedCitation" : "(Mullinger et al., 2013; Mullinger and Bowtell, 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2013; Mullinger and Bowtell, 2011). In addition, the subject was positioned such that electrodes Fp1 and Fp2 were at the iso-centre in the foot/head direction so as to further reduce the amplitude of the GAs ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "S1053-8119(10)01281-4 [pii] 10.1016/j.neuroimage.2010.09.079", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "20932913", "abstract" : "Large artefacts that compromise EEG data quality are generated when electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are carried out concurrently. The gradient artefact produced by the time-varying magnetic field gradients is the largest of these artefacts. Although average artefact correction (AAS) and related techniques can remove the majority of this artefact, the need to avoid amplifier saturation necessitates the use of a large dynamic range and strong low-pass filtering in EEG recording. Any intrinsic reduction in the gradient artefact amplitude would allow data with a higher bandwidth to be acquired without amplifier saturation, thus increasing the frequency range of neuronal activity that can be investigated using combined EEG-fMRI. Furthermore, gradient artefact correction methods assume a constant artefact morphology over time, so their performance is compromised by subject movement. Since the resulting, residual gradient artefacts can easily swamp signals from brain activity, any reduction in their amplitude would be highly advantageous for simultaneous EEG-fMRI studies. The aim of this work was to investigate whether adjustment of the subject's axial position in the MRI scanner can reduce the amplitude of the induced gradient artefact, before and after artefact correction using AAS. The variation in gradient artefact amplitude as a function of the subject's axial position was first investigated in six subjects by applying gradient pulses along the three Cartesian axes. The results of this study showed that a significant reduction in the gradient artefact magnitude can be achieved by shifting the subject axially by 4 cm towards the feet relative to the standard subject position (nasion at iso-centre). In a further study, the 4-cm shift was shown to produce a 40{%} reduction in the RMS amplitude (and a 31{%} reduction in the range) of the gradient artefact generated during the execution of a standard multi-slice, EPI sequence. By picking out signals occurring at harmonics of the slice acquisition frequency, it was also shown that the 4-cm shift led to a 36{%} reduction in the residual gradient artefact after AAS. Functional and anatomical MR data quality is not affected by the 4-cm shift, as the head remains in the homogeneous region of the static magnet field and gradients.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yan", "given" : "W X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2010/10/12", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "note" : "Mullinger, Karen J\nYan, Winston X\nBowtell, Richard\nG0901321(46386)/Medical Research Council/United Kingdom\nG9900259/Medical Research Council/United Kingdom\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2011 Feb 1;54(3):1942-50. Epub 2010 Oct 13.", "page" : "1942-1950", "title" : "Reducing the gradient artefact in simultaneous EEG-fMRI by adjusting the subject's axial position", "type" : "article-journal", "volume" : "54" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2011)", "plainTextFormattedCitation" : "(Mullinger et al., 2011)", "previouslyFormattedCitation" : "(Mullinger et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2011). Foam padding was placed around the subject's head to reduce motion-related artefacts. The EEG and MR scanner clocks were synchronised (Brain Products Synchbox), and the TR made equal to a multiple of the EEG sampling period, to ensure consistent sampling of the GA waveforms ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2006.04.231", "abstract" : "Investigating human brain function non-invasively by simultaneous EEG and fMRI measurements is gaining in popularity as more and better solutions to the inherent technical challenges emerge. We demonstrate the use of a commercially available frequency divider and phase-locking device for the purpose of synchronizing an MRI acquisition with a simultaneous recording of the EEG. Synchronization hugely improves the effectiveness of MRI artefact removal from the EEG signal by the common mean template subtraction method. It complements or substitutes post-processing techniques like filtering, thereby increasing the usable bandwidth of the EEG signal to about 150 Hz. This is important for covering the full range of human Gamma band activity. Similarly, synchronization eliminates the necessity for over-sampling of the EEG signal.", "author" : [ { "dropping-particle" : "", "family" : "Mandelkow", "given" : "H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Halder", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Boesiger", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brandeis", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "1120-1126", "title" : "Synchronization facilitates removal of MRI artefacts from concurrent EEG recordings and increases usable bandwidth", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "plainTextFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mandelkow et al., 2006; Mullinger et al., 2008b). The onset of every TR period was marked in the EEG data to facilitate GA correction. Simultaneous electromyogram (EMG) recordings were made from electrodes attached over the first dorsal interosseous (FDI) muscle of the right hand using a Brain Product EXG amplifier. Cardiac and respiratory cycles were simultaneously recorded using the scanner's physiological monitoring system (vector cardiogram (VCG) and respiratory belt). A T1-weighted anatomical image (MPRAGE sequence) with 1mm isotropic resolution was also acquired. EEG electrode locations were digitised (Polhemus Fastrak) to facilitate individualised co-registration of electrode positions with each subject’s anatomical image.ParadigmSubjects performed abduction movements of the right-hand index finger in time with an auditory cue (1 kHz tones, 50ms duration, 2.5Hz presentation rate) that was delivered to both ears via headphones, as previously employed in an MEG study ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Muthukumaraswamy, 2010)", "plainTextFormattedCitation" : "(Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Muthukumaraswamy, 2010). A single trial consisted of four abduction movements which were performed briskly following each auditory cue within the MR gradient quiet period of a single TR. The onset of the first cue was 250ms after the end of the MR acquisition in that TR, such that the cues occurred at 1000, 1400, 1800 and 2200ms relative to the start of a given TR, resulting in all movements occurring within a 1.5s window for each trial. Abduction trials were separated by a 16s (five 3s TR periods + 750ms MR acquisition + 250ms) resting baseline interval (see Figure 1). Subjects were instructed to fixate on a centrally displayed cross, to keep their hands by their sides and to remain as still as possible throughout the whole experiment. Immediately prior to the first auditory cue of each trial, a visual cue appeared, the fixation cross changed to a plus sign for 2s, warning the subjects to prepare for the upcoming trial. Subjects performed a 10-minute practice outside the scanner (50 trials of the same auditory cued abduction task for 1.5s, separated by an interval of 5.5s and EEG recorded) in order to familiarize themselves with the paradigm and were then subsequently positioned inside the MRI scanner where they each completed four runs of 30 trials during fMRI, resulting in 120 trials per subject in total.AnalysisEEGCardiac R-peaks were detected from the VCG recording and used to inform pulse artefact correction of data recording inside the scanner ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2008b)", "plainTextFormattedCitation" : "(Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2008b). For both EEG and EMG data, gradient and pulse artefacts were corrected in BrainVision Analyzer2 using sliding window templates formed from the averages of 45 and 21 artefacts respectively, which were subtracted from each occurrence of the respective artefacts. Data were subsequently downsampled (600Hz), bandpass filtered (EEG: 0.5-120Hz, EMG: 0.5-45Hz) and epoched into single-trials from -16s to 2s relative to the onset of the first auditory cue in each trial (BrainVision Analyzer2). Through visual inspection of the data, noisy EEG channels and trials that were contaminated with large motion artefacts, substantial EMG activity during the baseline period, or showed a lack of abduction movement in the EMG signal, were removed. This resulted in a group mean (±standard error [SE]) of 84 ± 2 trials remaining for further analysis. Independent component analysis of the EEG data (ICA, EEGLAB, ) was then used to remove eye-blinks/movements ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "S1388-2457(00)00386-2 [pii]", "ISBN" : "1388-2457 (Print) 1388-2457 (Linking)", "PMID" : "11018488", "abstract" : "OBJECTIVES: Electrical potentials produced by blinks and eye movements present serious problems for electroencephalographic (EEG) and event-related potential (ERP) data interpretation and analysis, particularly for analysis of data from some clinical populations. Often, all epochs contaminated by large eye artifacts are rejected as unusable, though this may prove unacceptable when blinks and eye movements occur frequently. METHODS: Frontal channels are often used as reference signals to regress out eye artifacts, but inevitably portions of relevant EEG signals also appearing in EOG channels are thereby eliminated or mixed into other scalp channels. A generally applicable adaptive method for removing artifacts from EEG records based on blind source separation by independent component analysis (ICA) (Neural Computation 7 (1995) 1129; Neural Computation 10(8) (1998) 2103; Neural Computation 11(2) (1999) 606) overcomes these limitations. RESULTS: Results on EEG data collected from 28 normal controls and 22 clinical subjects performing a visual selective attention task show that ICA can be used to effectively detect, separate and remove ocular artifacts from even strongly contaminated EEG recordings. The results compare favorably to those obtained using rejection or regression methods. CONCLUSIONS: The ICA method can preserve ERP contributions from all of the recorded trials and all the recorded data channels, even when none of the single trials are artifact-free.", "author" : [ { "dropping-particle" : "", "family" : "Jung", "given" : "T P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Makeig", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Westerfield", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Townsend", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Courchesne", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sejnowski", "given" : "T J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Clin Neurophysiol", "edition" : "2000/10/06", "id" : "ITEM-1", "issue" : "10", "issued" : { "date-parts" : [ [ "2000" ] ] }, "note" : "Jung, T P\nMakeig, S\nWesterfield, M\nTownsend, J\nCourchesne, E\nSejnowski, T J\n1RO1-NS34155-01/NS/NINDS NIH HHS/United States\nResearch Support, Non-U.S. Gov't\nResearch Support, U.S. Gov't, Non-P.H.S.\nResearch Support, U.S. Gov't, P.H.S.\nNetherlands\nClinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology\nClin Neurophysiol. 2000 Oct;111(10):1745-58.", "page" : "1745-1758", "title" : "Removal of eye activity artifacts from visual event-related potentials in normal and clinical subjects", "type" : "article-journal", "volume" : "111" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.jneumeth.2003.10.009 S0165027003003479 [pii]", "ISBN" : "0165-0270 (Print) 0165-0270 (Linking)", "PMID" : "15102499", "abstract" : "We have developed a toolbox and graphic user interface, EEGLAB, running under the crossplatform MATLAB environment (The Mathworks, Inc.) for processing collections of single-trial and/or averaged EEG data of any number of channels. Available functions include EEG data, channel and event information importing, data visualization (scrolling, scalp map and dipole model plotting, plus multi-trial ERP-image plots), preprocessing (including artifact rejection, filtering, epoch selection, and averaging), independent component analysis (ICA) and time/frequency decompositions including channel and component cross-coherence supported by bootstrap statistical methods based on data resampling. EEGLAB functions are organized into three layers. Top-layer functions allow users to interact with the data through the graphic interface without needing to use MATLAB syntax. Menu options allow users to tune the behavior of EEGLAB to available memory. Middle-layer functions allow users to customize data processing using command history and interactive 'pop' functions. Experienced MATLAB users can use EEGLAB data structures and stand-alone signal processing functions to write custom and/or batch analysis scripts. Extensive function help and tutorial information are included. A 'plug-in' facility allows easy incorporation of new EEG modules into the main menu. EEGLAB is freely available () under the GNU public license for noncommercial use and open source development, together with sample data, user tutorial and extensive documentation.", "author" : [ { "dropping-particle" : "", "family" : "Delorme", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Makeig", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci Methods", "edition" : "2004/04/23", "id" : "ITEM-2", "issue" : "1", "issued" : { "date-parts" : [ [ "2004" ] ] }, "note" : "Delorme, Arnaud\nMakeig, Scott\nResearch Support, Non-U.S. Gov't\nResearch Support, U.S. Gov't, P.H.S.\nNetherlands\nJournal of neuroscience methods\nJ Neurosci Methods. 2004 Mar 15;134(1):9-21.", "page" : "9-21", "title" : "EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis", "type" : "article-journal", "volume" : "134" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Delorme and Makeig, 2004; Jung et al., 2000)", "plainTextFormattedCitation" : "(Delorme and Makeig, 2004; Jung et al., 2000)", "previouslyFormattedCitation" : "(Delorme and Makeig, 2004; Jung et al., 2000)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Delorme and Makeig, 2004; Jung et al., 2000), with an average of 2 ICs (SE = 1) removed per subject, and data were re-referenced to an average of all non-noisy channels.Individual, 4-layer (scalp, skull, CSF, & brain) boundary element (BEM) head models were constructed from the T1 anatomical image of each subject using the Fieldtrip toolbox () ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1155/2011/156869", "ISBN" : "1687-5273 (Electronic)", "PMID" : "21253357", "abstract" : "This paper describes FieldTrip, an open source software package that we developed for the analysis of MEG, EEG, and other electrophysiological data. The software is implemented as a MATLAB toolbox and includes a complete set of consistent and user-friendly high-level functions that allow experimental neuroscientists to analyze experimental data. It includes algorithms for simple and advanced analysis, such as time-frequency analysis using multitapers, source reconstruction using dipoles, distributed sources and beamformers, connectivity analysis, and nonparametric statistical permutation tests at the channel and source level. The implementation as toolbox allows the user to perform elaborate and structured analyses of large data sets using the MATLAB command line and batch scripting. Furthermore, users and developers can easily extend the functionality and implement new algorithms. The modular design facilitates the reuse in other software packages.", "author" : [ { "dropping-particle" : "", "family" : "Oostenveld", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Maris", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schoffelen", "given" : "J M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Comput Intell Neurosci", "edition" : "2011/01/22", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2011" ] ] }, "note" : "Oostenveld, Robert\nFries, Pascal\nMaris, Eric\nSchoffelen, Jan-Mathijs\nResearch Support, Non-U.S. Gov't\nUnited States\nComputational intelligence and neuroscience\nComput Intell Neurosci. 2011;2011:156869. Epub 2010 Dec 23.", "page" : "156869", "title" : "FieldTrip: Open source software for advanced analysis of MEG, EEG, and invasive electrophysiological data", "type" : "article-journal", "volume" : "2011" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Oostenveld et al., 2011)", "plainTextFormattedCitation" : "(Oostenveld et al., 2011)", "previouslyFormattedCitation" : "(Oostenveld et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Oostenveld et al., 2011). A Linearly Constrained Minimum Variance (LCMV) beamformer ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "abstract" : "An algorithm for localization of electromagnetic activity in the central nervous system is explored. This algorithm generates a neural activity index map within the brain by passing surface recordings through a set of spatial filters. The covariance matrix of the surface recordings is used to optimize the spatial filters' responses. This approach is studied in simulated situations and in real data. The simulations show the method's capability to detect areas of activity without prior knowledge of the number of sources. The resolving power of the method increases with number of electrodes and signal-to-noise ratio, and it decreases with depth. The analysis of the electrophysiological data indicates that the method can distinguish simultaneously active areas in a realistic fashion. The analyzed recordings are bilateral median SEP responses, an epoch of spike activity showing several active regions and a recording with eye movement superimposed on spike activity. The method and the results are discussed in relation to current localization techniques.", "author" : [ { "dropping-particle" : "", "family" : "Drongelen", "given" : "W", "non-dropping-particle" : "van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yuchtman", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Veen", "given" : "BD", "non-dropping-particle" : "Van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Huffelen", "given" : "AC", "non-dropping-particle" : "van", "parse-names" : false, "suffix" : "" } ], "container-title" : "Brain Topography", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "1996" ] ] }, "page" : "39-49", "title" : "A spatial filtering technique to detect and localize multiple sources in the brain", "type" : "article-journal", "volume" : "9" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1109/10.623056", "ISSN" : "0018-9294", "PMID" : "9282479", "abstract" : "A spatial filtering method for localizing sources of brain electrical activity from surface recordings is described and analyzed. The spatial filters are implemented as a weighted sum of the data recorded at different sites. The weights are chosen to minimize the filter output power subject to a linear constraint. The linear constraint forces the filter to pass brain electrical activity from a specified location, while the power minimization attenuates activity originating at other locations. The estimated output power as a function of location is normalized by the estimated noise power as a function of location to obtain a neural activity index map. Locations of source activity correspond to maxima in the neural activity index map. The method does not require any prior assumptions about the number of active sources of their geometry because it exploits the spatial covariance of the source electrical activity. This paper presents a development and analysis of the method and explores its sensitivity to deviations between actual and assumed data models. The effect on the algorithm of covariance matrix estimation, correlation between sources, and choice of reference is discussed. Simulated and measured data is used to illustrate the efficacy of the approach.", "author" : [ { "dropping-particle" : "", "family" : "Veen", "given" : "B D", "non-dropping-particle" : "van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Drongelen", "given" : "W", "non-dropping-particle" : "van", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yuchtman", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Suzuki", "given" : "A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Biomedical", "id" : "ITEM-2", "issue" : "9", "issued" : { "date-parts" : [ [ "1997" ] ] }, "page" : "867-880", "title" : "Localization of brain electrical activity via linearly constrained minimum variance spatial filtering", "type" : "article-journal", "volume" : "44" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Robinson", "given" : "S E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vrba", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Recent Advances in Biomagnetism", "id" : "ITEM-3", "issued" : { "date-parts" : [ [ "1999" ] ] }, "page" : "302-305", "title" : "Functional neuroimaging by synthetic aperture magnetometry (SAM)", "type" : "article-journal", "volume" : "Tohoku Uni" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Robinson and Vrba, 1999; van Drongelen et al., 1996; van Veen et al., 1997)", "plainTextFormattedCitation" : "(Robinson and Vrba, 1999; van Drongelen et al., 1996; van Veen et al., 1997)", "previouslyFormattedCitation" : "(Robinson and Vrba, 1999; van Drongelen et al., 1996; van Veen et al., 1997)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Robinson and Vrba, 1999; van Drongelen et al., 1996; van Veen et al., 1997) was then employed to separately spatially localise changes in each subject’s gamma (55–80Hz) and beta (15-30Hz) frequency oscillations (filtered using 2nd order Butterworth filters implemented in Matlab) in response to abduction movements. The optimal frequency band for the localisation of gamma ERS was determined based on an iterative process of initially investigating time-frequency spectrograms created from broad gamma band (30-100Hz) source localisation and observing that consistently, across subjects, the peak gamma ERS was found in the 55-80Hz, gamma band range, in agreement with many previous findings ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.02.032", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18424182", "abstract" : "Electrocorticographic (ECoG) recordings obtained using intracranially implanted electrodes in epilepsy patients indicate that high gamma band (HGB) activity of sensorimotor cortex is focally increased during voluntary movement. These movement related HGB modulations may play an important role in sensorimotor cortex function. It is however currently not clear to what extent this type of neural activity can be detected using non-invasive electroencephalography (EEG) and how similar HGB responses in healthy human subjects are to those observed in epilepsy patients. Using the same arm reaching task, we have investigated spectral power changes both in intracranial ECoG recordings in epilepsy patients and in non-invasive EEG recordings optimized for detecting HGB activity in healthy subjects. Our results show a common HGB response pattern both in ECoG and EEG recorded above the sensorimotor cortex contralateral to the side of arm movement. In both cases, HGB activity increased around movement onset in the 60-90 Hz range and became most pronounced at reaching movement end. Additionally, we found EEG HGB activity above the frontal midline possibly generated by the anterior supplementary motor area (SMA), a region that was however not covered by the intracranial electrodes used in the present study. In summary, our findings show that HGB activity from human sensorimotor cortex can be non-invasively detected in healthy subjects using EEG, opening a new perspective for investigating the role of high gamma range neuronal activity both in function and dysfunction of the human cortical sensorimotor network. \u00a9 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Ball", "given" : "Tonio", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Demandt", "given" : "Evariste", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mutschler", "given" : "Isabella", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Neitzel", "given" : "Eva", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mehring", "given" : "Carsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vogt", "given" : "Klaus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Aertsen", "given" : "Ad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schulze-Bonhage", "given" : "Andreas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "302-310", "title" : "Movement related activity in the high gamma range of the human EEG", "type" : "article-journal", "volume" : "41" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.04.178", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18511304", "abstract" : "There has been increasing interest in the functional role of high-frequency (> 30??Hz) cortical oscillations accompanying various sensorimotor and cognitive tasks in humans. Similar \"high gamma\" activity has been observed in the motor cortex, although the role of this activity in motor control is unknown. Using whole-head MEG recordings combined with advanced source localization methods, we identified high-frequency (65 to 80??Hz) gamma oscillations in the primary motor cortex during self-paced movements of the upper and lower limbs. Brief bursts of gamma activity were localized to the contralateral precentral gyrus (MI) during self-paced index finger abductions, elbow flexions and foot dorsiflexions. In comparison to lower frequency (10-30??Hz) sensorimotor rhythms that are bilaterally suppressed prior to and during movement (Jurkiewicz et al., 2006), high gamma activity increased only during movement, reaching maximal increase 100 to 250??ms following EMG onset, and was lateralized to contralateral MI, similar to findings from intracranial EEG studies. Peak frequency of gamma activity was significantly lower during foot dorsiflexion (67.4 ?? 5.2??Hz) than during finger abduction (75.3 ?? 4.4??Hz) and elbow flexion (73.9 ?? 3.7??Hz) although markedly similar for left and right movements of the same body part within subjects, suggesting activation of a common underlying network for gamma oscillations in the left and right motor cortex. These findings demonstrate that voluntary movements elicit high-frequency gamma oscillations in the primary motor cortex that are effector specific, and possibly reflect the activation of cortico-subcortical networks involved in the feedback control of discrete movements. ?? 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bells", "given" : "Sonya", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaetz", "given" : "William", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bostan", "given" : "Andreea C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "1", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "332-342", "title" : "Self-paced movements induce high-frequency gamma oscillations in primary motor cortex", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-3", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Ball et al., 2008; Cheyne et al., 2008; Muthukumaraswamy, 2010)", "manualFormatting" : "(Ball et al., 2008; Cheyne et al., 2008; Muthukumaraswamy, 2010", "plainTextFormattedCitation" : "(Ball et al., 2008; Cheyne et al., 2008; Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Ball et al., 2008; Cheyne et al., 2008; Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Ball et al., 2008; Cheyne et al., 2008; Muthukumaraswamy, 2010; for reviews, ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.3389/fnhum.2013.00138", "ISBN" : "1662-5161 (Electronic)\\n1662-5161 (Linking)", "ISSN" : "1662-5161", "PMID" : "23596409", "abstract" : "In recent years high-frequency brain activity in the gamma-frequency band (30-80 Hz) and above has become the focus of a growing body of work in MEG/EEG research. Unfortunately, high-frequency neural activity overlaps entirely with the spectral bandwidth of muscle activity (~20-300 Hz). It is becoming appreciated that artifacts of muscle activity may contaminate a number of non-invasive reports of high-frequency activity. In this review, the spectral, spatial, and temporal characteristics of muscle artifacts are compared with those described (so far) for high-frequency neural activity. In addition, several of the techniques that are being developed to help suppress muscle artifacts in MEG/EEG are reviewed. Suggestions are made for the collection, analysis, and presentation of experimental data with the aim of reducing the number of publications in the future that may contain muscle artifacts.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Frontiers in Human Neuroscience", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1-11", "title" : "High-frequency brain activity and muscle artifacts in MEG/EEG: a review and recommendations", "type" : "article-journal", "volume" : "7" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.3389/fnhum.2013.00575", "ISBN" : "1662-5161 (Electronic)\\r1662-5161 (Linking)", "ISSN" : "1662-5161", "PMID" : "24062675", "abstract" : "The human motor cortex exhibits transient bursts of high frequency gamma oscillations in the 60 to 90 Hz range during movement. It has been proposed that gamma oscillations generally reflect local intracortical activity. However, movement-evoked gamma is observed simultaneously in both cortical and subcortical (basal ganglia) structures and thus appears to reflect long-range cortical-subcortical interactions. Recent evidence suggests that gamma oscillations do not simply reflect sensory reafference, but have a facilitative role in movement initiation. Here we summarize contributions of MEG to our understanding of movement-evoked gamma oscillations, including evidence that transient gamma bursts during the performance of specific movements constitutes a stereotyped spectral and temporal pattern within individuals \u2013 a gamma \u201cfingerprint\u201d \u2013 that is highly stable over time. Although their functional significance remains to be fully understood, movement-evoked gamma oscillations may represent frequency specific tuning within cortical-subcortical networks that can be monitored non-invasively using MEG during a variety of motor tasks, and may provide important information regarding cortical dynamics of ongoing motor control.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ferrari", "given" : "Paul", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Frontiers in Human Neuroscience", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1-7", "title" : "MEG studies of motor cortex gamma oscillations: evidence for a gamma \u201cfingerprint\u201d in the brain?", "type" : "article-journal", "volume" : "7" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.expneurol.2012.08.030", "ISBN" : "1090-2430 (Electronic)\\n0014-4886 (Linking)", "ISSN" : "00144886", "PMID" : "22981841", "abstract" : "The human sensorimotor cortex demonstrates a variety of oscillatory activity that is strongly modulated by movement and somatosensory input. Studies using scalp EEG and intracranial electrical recordings have provided much of our current knowledge regarding the frequency and temporal specificity of these sensorimotor rhythms and their relationship to various movement parameters, however with limitations in identifying the underlying neural sources, and the variety of motor behaviors that can be studied, respectively. Magnetoencephalography (MEG) recordings, combined with spatial filtering source reconstruction methods, provide an ideal non-invasive method for the localization of sensorimotor rhythms and for describing their precise time course during a variety of motor tasks. This review describes the application of MEG to the study of oscillatory activity in the human sensorimotor cortex, including advances in localization techniques and recent contributions of MEG to our understanding of the functional role of these oscillations in both adult and developmental populations. \u00a9 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas Owen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Experimental Neurology", "id" : "ITEM-3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "27-39", "title" : "MEG studies of sensorimotor rhythms: A review", "type" : "article", "volume" : "245" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)", "manualFormatting" : "Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)", "plainTextFormattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)", "previouslyFormattedCitation" : "(Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Cheyne and Ferrari, 2013; Cheyne, 2013; Muthukumaraswamy, 2013). For each subject and frequency band (beta or gamma), source power during the active (0s to 1.5s) and passive (-9.0s to -7.5s) time windows, defined relative to the first cue onset, were calculated. The passive window definition in the baseline interval, during the first MR-quiet period that preceded the visual probe cue of that trial, was chosen to avoid both the periods of MR acquisition and any brain activity occurring due to the visual cue. Subsequently, pseudo T-statistic (T-statistic) maps were computed as the ratio of the difference in source power between the active and passive windows, divided by the sum of the noise power estimates inherent to the sensors during both active and passive windows ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/S0074-7742(05)68006-3", "ISBN" : "0123668697", "ISSN" : "00747742", "PMID" : "16443013", "abstract" : "Magnetoencephalography (MEG) measures the magnetic fields outside the head created by electrical neuronal activity. The aim of many studies is to subsequently determine the spatiotemporal characteristics of these neuronal sources on the basis of the extracranial recordings, which means that an inverse problem needs to be solved. The MEG inverse problem is theoretically insoluble; just as inferring a three-dimensional scene from a two-dimensional image is insoluble. However, we are able to interpret cinematic images because we make certain assumptions about the world (the size of people, the way shadows fall) that allow us to achieve a percept. In MEG we are searching for a similar set of assumptions on which to base algorithms to interpret the MEG data. Recent work has shown that a class of algorithms used to solve the MEG inverse problem produce functionally plausible and verifiable results. These algorithms make the assumption that no two distinct cortical areas are perfectly linearly correlated in their activation time series and it has been shown empirically that this assumption is often justified. First, the spatial concurrence of beamformer images of induced neuronal activity and the BOLD (blood oxygenation level dependent) functional magnetic resonance imaging (fMRI) response was demonstrated in a biological motion and a letter fluency task (Singh et al., 2002) and more recently in a working memory task (Coppola et al., 2004). Second, beamformer analysis has been applied successfully in various experimental paradigms, ranging from experiments involving primary visual, auditory, and somatosensory cortices as well as the use of more cognitively demanding paradigms (e.g., Fawcett et al., 2004; Furlong et al., 2004; Gaetz and Cheyne, 2003; Hashimoto et al., 2001; Herdman et al., 2003; Hobson et al., 2005; Kamada et al., 1998; Ploner et al., 2002; Taniguchi et al., 2000; Ukai et al., 2002; also see Hillebrand et al., 2005, for review). One of the main advantages of beamformer analysis is that induced changes in cortical oscillatory power that do not result in a strong average-evoked response can be identified and localized. In particular, by using an active and control state, stimulus induced increases and decreases in cortical rhythms, known as event-related synchronization (ERS) and event-related desynchronization (ERD), respectively (Pfurtscheller and Lopes da Silva, 1999), can be quantified. Such changes in ongoing activity have been shown to play\u2026", "author" : [ { "dropping-particle" : "", "family" : "Hillebrand", "given" : "Arjan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barnes", "given" : "Gareth R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "International Review of Neurobiology", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2005" ] ] }, "page" : "149-171", "title" : "Beamformer Analysis of MEG Data", "type" : "article", "volume" : "68" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Robinson", "given" : "S E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vrba", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Recent Advances in Biomagnetism", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "1999" ] ] }, "page" : "302-305", "title" : "Functional neuroimaging by synthetic aperture magnetometry (SAM)", "type" : "article-journal", "volume" : "Tohoku Uni" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Hillebrand and Barnes, 2005; Robinson and Vrba, 1999)", "plainTextFormattedCitation" : "(Hillebrand and Barnes, 2005; Robinson and Vrba, 1999)", "previouslyFormattedCitation" : "(Hillebrand and Barnes, 2005; Robinson and Vrba, 1999)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Hillebrand and Barnes, 2005; Robinson and Vrba, 1999).The maximum peak ?-statistic location of the gamma power ERS and minimum peak ?-statistic location of the beta power ERD in the contralateral primary motor cortex (cM1) defined the site of a gamma and a beta virtual electrode (VE). A broadband (1-120Hz) timecourse of neural activity was then extracted from these two VE locations, by multiplying the channel level data by the respective broadband beamformer weights. Time-frequency spectrograms of gamma and beta VE data were calculated using a multitaper wavelet approach ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Scheeringa et al., 2011)", "previouslyFormattedCitation" : "(Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Scheeringa et al., 2011). Windows of 0.4s duration were moved across the data in steps of 50ms, resulting in a frequency resolution of 2.5Hz, and the use of seven tapers resulted in a spectral smoothing of ±10Hz. Using the mean of the passive window data as baseline the spectrograms were converted to display change in activity relative to baseline. Separately for each subject, VE timecourses were filtered into the gamma and beta bands, Hilbert transformed and then the average power during the active window was calculated for each trial ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.06.080", "abstract" : "We recorded auditory-evoked potentials (AEPs) during simultaneous, continuous fMRI and identified trial-to-trial correlations between the amplitude of electrophysiological responses, characterised in the time domain and the time-frequency domain, and the hemodynamic BOLD response. Cortical AEPs were recorded from 30 EEG channels within the 3 T MRI scanner with and without the collection of simultaneous BOLD fMRI. Focussing on the Cz (vertex) EEG response, single-trial AEP responses were measured from time-domain waveforms. Furthermore, a novel method was used to characterise the single-trial AEP response within three regions of interest in the time-frequency domain (TF-ROIs). The latency and amplitude values of the N1 and P2 AEP peaks during fMRI scanning were not significantly different from the Control session (p{>}0.16). BOLD fMRI responses to the auditory stimulation were observed in bilateral secondary auditory cortices as well as in the right precentral and postcentral gyri, anterior cingulate cortex (ACC) and supplementary motor cortex (SMC). Significant single-trial correlations were observed with a voxel-wise analysis, between (1) the magnitude of the EEG TF-ROI1 (70-800 ms post-stimulus, 1-5 Hz) and the BOLD response in right primary (Heschl's gyrus) and secondary (STG, planum temporale) auditory cortex; and (2) the amplitude of the P2 peak and the BOLD response in left pre- and postcentral gyri, the ACC and SMC. No correlation was observed with single-trial N1 amplitude on a voxel-wise basis. An fMRI-ROI analysis of functionally-identified auditory responsive regions identified further single-trial correlations of BOLD and EEG responses. The TF amplitudes in TF-ROI1 and TF-ROI2 (20-400 ms post-stimulus, 5-15 Hz) were significantly correlated with the BOLD response in all bilateral auditory areas investigated (planum temporale, superior temporal gyrus and Heschl's gyrus). However the N1 and P2 peak amplitudes, occurring at similar latencies did not show a correlation in these regions. N1 and P2 peak amplitude did correlate with the BOLD response in bilateral precentral and postcentral gyri and the SMC. Additionally P2 and TF-ROI1 both correlated with the ACC. TF-ROI3 (400-900 ms post-stimulus, 4-10 Hz) correlations were only observed in the ACC and SMC. Across the group, the subject-mean N1 peak amplitude correlated with the BOLD response amplitude in the primary and secondary auditory cortices bilaterally, as well as the right precentral gyru\u2026", "author" : [ { "dropping-particle" : "", "family" : "Mayhew", "given" : "Stephen D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dirckx", "given" : "Sharon G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Niazy", "given" : "Rami K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Iannetti", "given" : "Gian D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wise", "given" : "Richard G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "849-864", "title" : "EEG signatures of auditory activity correlate with simultaneously recorded fMRI responses in humans", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mayhew", "given" : "S D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bagshaw", "given" : "A P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Francis", "given" : "S T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2014" ] ] }, "page" : "263-274", "title" : "Evidence that the negative BOLD response is neuronal in origin: a simultaneous EEG-BOLD-CBF study in humans", "type" : "article-journal", "volume" : "94" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mayhew et al., 2010; Mullinger et al., 2014)", "plainTextFormattedCitation" : "(Mayhew et al., 2010; Mullinger et al., 2014)", "previouslyFormattedCitation" : "(Mayhew et al., 2010; Mullinger et al., 2014)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mayhew et al., 2010; Mullinger et al., 2014). These single trial power values were then mean-subtracted to form regressors of gamma and beta power, which represented the trial-by-trial variability in single-trial stimulus response amplitudes, for subsequent GLM analysis of fMRI data. The amplitude of rejected trials was set to the mean value (zero). EEG data recorded outside the scanner were analysed using equivalent methodology, to provide comparison of data quality with the inside scanner recordings.fMRIfMRI data were processed using FSL v5.0.9 (). Data from each subject were corrected for physiological noise using a RETROICOR approach (Glover et al., 1999) implemented using in-house Matlab code, motion corrected (MCFLIRT), spatially smoothed (5mm FWHM Gaussian kernel), high-pass temporally filtered (100s cutoff), registered to their T1 anatomical brain image (FLIRT), and normalised to the MNI 2mm standard brain. GLM analyses were performed using FEAT v6.0. First-level analysis was performed employing four regressors: 1) boxcar abduction movement, 2) boxcar visual probe cue, 3&4) parametric modulation of single-trial gamma and beta neuronal responses, respectively. All regressors were convolved with the double-gamma HRF. Both positive and negative contrasts were assessed for each regressor. For each subject and frequency band, ?rst-level results were combined across all four runs using a second-level, ?xed effects analysis to calculate an average response per subject. These results were then combined across all subjects at the third, group-level using a FLAME mixed-effects analysis ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2003.12.023 S1053811903007894 [pii]", "ISBN" : "1053-8119 (Print) 1053-8119 (Linking)", "PMID" : "15050594", "abstract" : "Functional magnetic resonance imaging studies often involve the acquisition of data from multiple sessions and/or multiple subjects. A hierarchical approach can be taken to modelling such data with a general linear model (GLM) at each level of the hierarchy introducing different random effects variance components. Inferring on these models is nontrivial with frequentist solutions being unavailable. A solution is to use a Bayesian framework. One important ingredient in this is the choice of prior on the variance components and top-level regression parameters. Due to the typically small numbers of sessions or subjects in neuroimaging, the choice of prior is critical. To alleviate this problem, we introduce to neuroimage modelling the approach of reference priors, which drives the choice of prior such that it is noninformative in an information-theoretic sense. We propose two inference techniques at the top level for multilevel hierarchies (a fast approach and a slower more accurate approach). We also demonstrate that we can infer on the top level of multilevel hierarchies by inferring on the levels of the hierarchy separately and passing summary statistics of a noncentral multivariate t distribution between them.", "author" : [ { "dropping-particle" : "", "family" : "Woolrich", "given" : "M W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Behrens", "given" : "T E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Beckmann", "given" : "C F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jenkinson", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "S M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2004/03/31", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2004" ] ] }, "note" : "Woolrich, Mark W\nBehrens, Timothy E J\nBeckmann, Christian F\nJenkinson, Mark\nSmith, Stephen M\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2004 Apr;21(4):1732-47.", "page" : "1732-1747", "title" : "Multilevel linear modelling for FMRI group analysis using Bayesian inference", "type" : "article-journal", "volume" : "21" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Woolrich et al., 2004)", "plainTextFormattedCitation" : "(Woolrich et al., 2004)", "previouslyFormattedCitation" : "(Woolrich et al., 2004)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Woolrich et al., 2004). Since our a-priori hypothesis was to investigate motor fMRI responses and their correlation with gamma and beta EEG activity, a mask of motor cortex (Oxford–Harvard cortical atlas, FSL) was applied as pre-threshold mask to all group-level statistical maps before cluster correction. Main effect (boxcar model of the task) and the single trial EEG regressor correlation BOLD Z-statistic images were threshold using Z > 2.3 and cluster corrected signi?cance threshold of p < 0.05. Results Stage 1: Feasibility testingSafety testingThe temperature changes measured at all thermometer sensors during the GE-EPI sequence are plotted in Figure 2. The greatest heating was observed in the ECG channel, which showed a ~0.5°C increase. This temperature increase occurred gradually over the first 10 minutes and then stabilised and showed no further change. Nominal heating was observed in the other channels. The higher SAR of the PCASL sequence resulted in a greater heating effect than the GE-EPI, again the largest temperature increase was seen in the ECG channel (~0.9°C) with increases in other channels (TP8 = ~0.8°C) also observed (Figure S1). As this GE-EPI sequence, with parameters chosen to maximise SAR, showed no heating effect close to 1°C, the use of the MB GE-EPI (with parameters resulting in lower SAR) with the EEG system was regarded safe for the following experiments ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/jmri.21583", "ISBN" : "1053-1807 (Print)\\r1053-1807 (Linking)", "ISSN" : "10531807", "PMID" : "18972332", "abstract" : "PURPOSE To investigate heating during postimplantation localization of intracranial electroencephalograph (EEG) electrodes by MRI. MATERIALS AND METHODS A phantom patient with a realistic arrangement of electrodes was used to simulate tissue heating during MRI. Measurements were performed using 1.5 Tesla (T) and 3T MRI scanners, using head- and body-transmit RF-coils. Two electrode-lead configurations were assessed: a \"standard\" condition with external electrode-leads physically separated and a \"fault\" condition with all lead terminations electrically shorted. RESULTS Using a head-transmit-receive coil and a 2.4 W/kg head-average specific absorption rate (SAR) sequence, at 1.5T the maximum temperature change remained within safe limits (<1 degrees C). Under \"standard\" conditions, we observed greater heating (<or=2.0 degrees C) at 3T on one system and similar heating (<1 degrees C) on a second, compared with the 1.5T system. In all cases these temperature maxima occurred at the grid electrode. In the \"fault\" condition, larger temperature increases were observed at both field strengths, particularly for the depth electrodes. Conversely, with a body-transmit coil at 3T significant heating (+6.4 degrees C) was observed (same sequence, 1.2/0.5 W/kg head/body-average) at the grid electrode under \"standard\" conditions, substantially exceeding safe limits. These temperature increases neglect perfusion, a major source of heat dissipation in vivo. CONCLUSION MRI for intracranial electrode localization can be performed safely at both 1.5T and 3T provided a head-transmit coil is used, electrode leads are separated, and scanner-reported SARs are limited as determined in advance for specific scanner models, RF coils and implant arrangements. Neglecting these restrictions may result in tissue injury.", "author" : [ { "dropping-particle" : "", "family" : "Carmichael", "given" : "David W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Thornton", "given" : "John S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rodionov", "given" : "Roman", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Thornton", "given" : "Rachel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McEvoy", "given" : "Andrew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Allen", "given" : "Philip J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lemieux", "given" : "Louis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Magnetic Resonance Imaging", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "1233-1244", "title" : "Safety of localizing epilepsy monitoring intracranial electroencephalograph electrodes using MRI: Radiofrequency-induced heating", "type" : "article-journal", "volume" : "28" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Medicines and Healthcare Products Regulatory Agency", "given" : "", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-2", "issue" : "March", "issued" : { "date-parts" : [ [ "2015" ] ] }, "publisher-place" : "UK", "title" : "Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use", "type" : "article-journal" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Carmichael et al., 2008; Medicines and Healthcare Products Regulatory Agency, 2015)", "plainTextFormattedCitation" : "(Carmichael et al., 2008; Medicines and Healthcare Products Regulatory Agency, 2015)", "previouslyFormattedCitation" : "(Carmichael et al., 2008; Medicines and Healthcare Products Regulatory Agency, 2015)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Carmichael et al., 2008; Medicines and Healthcare Products Regulatory Agency, 2015).Image quality: tSNRThe variation in BOLD tSNR with MB factor = 1-3 and slice spacing acquisition is summarised in Table 1. These data indicate that the variability in tSNR between subjects was far larger than the variability of tSNR with imaging parameters. Figure 3 shows the spatial variation in tSNR over a single slice for each subject for the two sparse imaging acquisition sequences tested, which were the most promising sequences for our EEG-fMRI application. Visual inspection of the images in Figure 3 and direct comparison of the mean and standard deviation of tSNR within subjects shows no clear change in tSNR (12.6 ± 22% between MB factor 2 to 3) between MB factors. Since, for sparse sequences, using a MB factor of 3 compared with 2 results in a 33% reduction in the time required to acquire the same number of slices the MB factor of 3 was chosen for the EEG-fMRI experiment, to maximise the duration of the MR quiet-period for EEG measurements without degradation of the tSNR.Study 2: EEG-fMRI motor studyAll subjects performed the abduction task as instructed, judged by visual inspection of the EMG data showing increases in power during brisk finger movements which accurately timed to the auditory cues, and EMG power returning to rest levels during the baseline periods showing subjects remained still in these periods. Mean rectified EMG activity during the passive and active periods is shown for a representative subject in Figure 4. Figure 5 shows the group average T-statistic map of changes in both EEG gamma- and beta-power during the active window compared to the passive window. An increase in gamma power (ERS, positive T values, Fig. 5a) was only observed in contralateral M1, whereas a decrease in beta power (ERD, negative T values, Fig. 5b) was observed in bilaterally in contralateral and ipsilateral M1. Specifically, the mean of the individual subject VE locations in cM1 for the gamma ERS was found at: [-21±3, -31±3, 59±3] mm [MNI:x,y,z] (see Fig 5a, crosshair) and the beta ERD was found at [-39±3, -32±2, 51±4] mm (see Fig 5b, crosshair), where errors denote standard error over subjects. Both these locations lie in the post-central gyrus, the gamma VE location was found to be significantly more medial (t(9) = 3.76, p=0.004 paired t-test) than the beta VE location, but no difference in the y (t(9) = 0.41, p=0.69) or z (t(9) = 1.32, p=0.21) co-ordinates was observed.Figure 6 shows the group mean time-frequency spectrograms measured from cM1 for the gamma (Fig 6a&b) and beta (Fig 6c&d) VE locations. Figures 6a&c display the mean time-frequency spectrogram for the whole 18s duration of the abduction trial and preceding inter-trial interval, with Figure 6b&d showing the active and passive periods only. The broadband increases in power (red vertical stripes lasting ~750ms and occurring every 3s) show the effect of the residual GAs caused by the MRI data acquisition on the EEG power spectrum. It is clear that neuronal EEG responses above 20 Hz recorded during MRI data acquisition are corrupted by residual GAs with signal degradation increasing with increasing frequency (Fig. 6a&c). Note that, due to the way the trials were epoched, the increase in <30Hz power between -16s and -14s represents the post-movement alpha/beta rebound. By selecting the active (0 to 1.5s) and passive (-9 to -7.5s) time windows during MR quiet periods a reliable comparison of neuronal signals between rest and task was made for both the gamma and beta bands (Fig. 6b&d). During the active window, when the FDI abduction movements were performed, ERS of gamma band power (55-80Hz) and ERD of beta band power (15-30Hz) occurred compared with the passive window of baseline resting fixation with no movement (Fig. 6b&d). As expected due to the VE definition, stronger gamma power ERS was observed in the gamma VE than the beta VE, and stronger beta power ERD was observed in the beta VE than in the gamma VE. Comparison of these results with those from data recorded outside the scanner (Figure S2 & S3), show that very similar gamma and beta responses were measured in both recordings, providing confidence in the quality of our data inside the scanner.As expected across 10 subjects, we observed a significant main-effect (correlation with boxcar regressor) positive BOLD response to the abduction movements in the motor cortex, with the peak voxel (Z=5.12, p<1x10-19) lying within the masked region found at [-38, -32, 66] mm [MNI:x,y,z] in cM1, as shown in Figure 7, red-orange. With a second peak (Z=4.97, p<1x10-19) found on the midline at [-4, -14, 70] mm [MNI:x,y,z]. In addition a positive correlation between single-trial gamma power ERS and the BOLD response was observed in cM1, with the peak (Z=3.11, p<0.001) located at [-32, -42, 60] mm [MNI:x,y,z] (Fig 7, green) with additional responses in the ipsilateral primary motor cortex with the peak (Z=3.02, p<0.01) located at [34, -42, 60] mm [MNI:x,y,z] and on the midline with peak (Z=2.97, p<0.01) located at [2, -36, 56] mm [MNI:x,y,z]. No significant negative correlations were observed with the boxcar or gamma band regressors. No significant positive or negative correlations between single-trial beta and BOLD responses were observed. DiscussionHere, through a series of experiments we show that, with the right safety precautions and MRI sequence choice, it is safe to simultaneously acquire EEG data with MB fMRI data, despite the higher peak RF power required for MB acquisitions compared with conventional fMRI acquisitions. We also show that, for the implementation of MB used here, there is no measurable degradation of the fMRI signal tSNR when moving to a sparse acquisition with a MB factor of 3 compared with the conventional continuous equi-spacing acquisition with no MB factor, allowing for the presence of physiological noise. We finally show the considerable gains that can be achieved in using MB fMRI with concurrent EEG data acquisition by studying gamma-BOLD coupling with a simple motor task. We were able to reliably detect the gamma response to finger abductions within cM1 and found that this response was positively correlated with the BOLD response in bilateral primary motor cortex with activation extending directly posterior to the hand-knob area of the contralateral motor cortex. Safety and signal quality considerationsWe show that for a GE-EPI sequence using a MB factor of 4 resulting in a B1 RMS=1.09μT, SAR/head=22% that the maximum heating observed over a 20 minute period was ~0.5 ?C (Figure 2) which is considerably less than the recommended 1 ?C safety limit ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Medicines and Healthcare Products Regulatory Agency", "given" : "", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "March", "issued" : { "date-parts" : [ [ "2015" ] ] }, "publisher-place" : "UK", "title" : "Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use", "type" : "article-journal" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)", "plainTextFormattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)", "previouslyFormattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Medicines and Healthcare Products Regulatory Agency, 2015). Furthermore the majority of this 0.5 ?C temperature increase was observed within the first 5-6 minutes of scanning after which the temperature remained relatively constant suggesting that there is not a linear heating effect over time. Therefore even if data were continuously acquired for a longer period, which is uncommon in neuroimaging studies, the risk to the subject is unlikely to increase greatly. A similar pattern of heating was observed for the PCASL sequence where the greatest heating occurred in the first few minutes before a plateau was reached (Figure S1). However, this heating effect was far greater, up to ~0.9 ?C over the electrodes and locations measured, reflecting the increased B1 power used in that sequence (B1 RMS=1.58μT, SAR/head=46%). As this temperature rise was only just within the safe limit for human tissue ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Medicines and Healthcare Products Regulatory Agency", "given" : "", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "March", "issued" : { "date-parts" : [ [ "2015" ] ] }, "publisher-place" : "UK", "title" : "Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use", "type" : "article-journal" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)", "plainTextFormattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)", "previouslyFormattedCitation" : "(Medicines and Healthcare Products Regulatory Agency, 2015)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Medicines and Healthcare Products Regulatory Agency, 2015) and given that not all locations on the phantom were monitored, we would strongly suggest sequences such as MB-PCASL should not be used with concurrent EEG recordings. Although we didn’t record temperature data from occipital electrodes due to practical limitations, we believe temperature increases at T7/T8 are likely to approximate the O1/O2 electrodes, due to similar wire lengths. The greatest heating effect in both GE-EPI and PCASL scans was observed in the ECG lead. This lead is considerably longer than the other leads in the EEG cap, which probably resulted in greater RF absorption in this lead ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.ijpsycho.2007.06.008", "abstract" : "Although the focus of attention on data degradation during simultaneous MRI/EEG recording has to date largely been upon EEG artefacts, the presence of the conducting wires and electrodes of the EEG recording system also causes some degradation of MRI data quality. This may result from magnetic susceptibility effects which lead to signal drop-out and image distortion, as well as the perturbation of the radiofrequency fields, which can cause local signal changes and a global reduction in the signal to noise ratio (SNR) of magnetic resonance images. Here, we quantify the effect of commercially available 32 and 64 electrode caps on the quality of MR images obtained in scanners operating at magnetic fields of 1.5, 3 and 7 T, via the use of MR-based, field-mapping techniques and analysis of the SNR in echo planar image time series. The electrodes are shown to be the dominant source of magnetic field inhomogeneity, although the localised nature of the field perturbation that they produce means that the effect on the signal intensity from the brain is not significant. In the particular EEG caps investigated here, RF inhomogeneity linked to the longer ECG and EOG leads causes some reduction in the signal intensity in images obtained at 3 and 7 T. Measurements of the standard deviation of white matter signal in EPI time series indicates that the introduction of the EEG cap produces a small reduction in the image signal to noise ratio, which increases with the number of electrodes used.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Debener", "given" : "Stefan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Coxon", "given" : "Ronald", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "International Journal of Psychophysiology", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "178-188", "title" : "Effects of simultaneous EEG recording on MRI data quality at 1.5, 3 and 7 tesla", "type" : "article-journal", "volume" : "67" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2008a)", "plainTextFormattedCitation" : "(Mullinger et al., 2008a)", "previouslyFormattedCitation" : "(Mullinger et al., 2008a)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2008a) causing the larger heating effect observed here. Given the potential to use the VCG system, supplied by the MRI manufacturer, to monitor the cardiac cycle ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2008b)", "plainTextFormattedCitation" : "(Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Mullinger et al., 2008b) it would be possible to reduce the risk of heating effects by removing the ECG lead and electrode from the EEG setup. However, given the increase in temperature (~0.8 ?C) in the Tp8 electrode, which also has a relatively long lead, the removal of the ECG lead alone is unlikely to ensure that high SAR sequences can be run safely with EEG system present. These findings are in general agreement with recent work that also considered safety implication of MB ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1371/journal.pone.0178409", "ISBN" : "1111111111", "ISSN" : "19326203", "PMID" : "28552957", "abstract" : "PURPOSE Concurrent EEG and fMRI is increasingly used to characterize the spatial-temporal dynamics of brain activity. However, most studies to date have been limited to conventional echo-planar imaging (EPI). There is considerable interest in integrating recently developed high-speed fMRI methods with high-density EEG to increase temporal resolution and sensitivity for task-based and resting state fMRI, and for detecting interictal spikes in epilepsy. In the present study using concurrent high-density EEG and recently developed high-speed fMRI methods, we investigate safety of radiofrequency (RF) related heating, the effect of EEG on cortical signal-to-noise ratio (SNR) in fMRI, and assess EEG data quality. MATERIALS AND METHODS The study compared EPI, multi-echo EPI, multi-band EPI and multi-slab echo-volumar imaging pulse sequences, using clinical 3 Tesla MR scanners from two different vendors that were equipped with 64- and 256-channel MR-compatible EEG systems, respectively, and receive only array head coils. Data were collected in 11 healthy controls (3 males, age range 18-70 years) and 13 patients with epilepsy (8 males, age range 21-67 years). Three of the healthy controls were scanned with the 256-channel EEG system, the other subjects were scanned with the 64-channel EEG system. Scalp surface temperature, SNR in occipital cortex and head movement were measured with and without the EEG cap. The degree of artifacts and the ability to identify background activity was assessed by visual analysis by a trained expert in the 64 channel EEG data (7 healthy controls, 13 patients). RESULTS RF induced heating at the surface of the EEG electrodes during a 30-minute scan period with stable temperature prior to scanning did not exceed 1.0\u00b0 C with either EEG system and any of the pulse sequences used in this study. There was no significant decrease in cortical SNR due to the presence of the EEG cap (p > 0.05). No significant differences in the visually analyzed EEG data quality were found between EEG recorded during high-speed fMRI and during conventional EPI (p = 0.78). Residual ballistocardiographic artifacts resulted in 58% of EEG data being rated as poor quality. CONCLUSION This study demonstrates that high-density EEG can be safely implemented in conjunction with high-speed fMRI and that high-speed fMRI does not adversely affect EEG data quality. However, the deterioration of the EEG quality due to residual ballistocardiographic artifacts remains a signi\u2026", "author" : [ { "dropping-particle" : "", "family" : "Foged", "given" : "Mette Thrane", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lindberg", "given" : "Ulrich", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vakamudi", "given" : "Kishore", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Larsson", "given" : "Henrik B.W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pinborg", "given" : "Lars H.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kj\u00f1r", "given" : "Troels W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fabricius", "given" : "Martin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Svarer", "given" : "Claus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ozenne", "given" : "Brice", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Thomsen", "given" : "Carsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Beniczky", "given" : "S\u00e1ndor", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Paulson", "given" : "Olaf B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Posse", "given" : "Stefan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "PLoS ONE", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2017" ] ] }, "title" : "Safety and EEG data quality of concurrent high-density EEG and high-speed fMRI at 3 Tesla", "type" : "article-journal", "volume" : "12" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Foged et al., 2017)", "plainTextFormattedCitation" : "(Foged et al., 2017)", "previouslyFormattedCitation" : "(Foged et al., 2017)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Foged et al., 2017). It is also important to note that minimal heating effects were observed at the MRI scanner bore location suggesting that the MR scanning was not increasing the ambient temperature of the bore. Therefore the observed electrode heating specifically arose from the interaction between the EEG system and the RF slice excitation pulses. These data highlight the potential dangers of using MB sequences for EEG-fMRI where high SAR values can arise from the increased B1 ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/mrm.22845", "ISBN" : "1522-2594", "ISSN" : "07403194", "PMID" : "21381106", "abstract" : "Radiofrequency magnetic fields are critical to nuclear excitation and signal reception in magnetic resonance imaging. The interactions between these fields and human tissues in anatomical geometries results in a variety of effects regarding image integrity and safety of the human subject. In recent decades, numerical methods of calculation have been used increasingly to understand the effects of these interactions and aid in engineering better, faster, and safer equipment and methods. As magnetic resonance imaging techniques and technology have evolved through the years, so to have the requirements for meaningful interpretation of calculation results. Here, we review the basic physics of radiofrequency electromagnetics in magnetic resonance imaging and discuss a variety of ways radiofrequency field calculations are used in magnetic resonance imaging in engineering and safety assurance from simple systems and sequences through advanced methods of development for the future.", "author" : [ { "dropping-particle" : "", "family" : "Collins", "given" : "Christopher M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wang", "given" : "Zhangwei", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magnetic Resonance in Medicine", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "1470-1482", "title" : "Calculation of radiofrequency electromagnetic fields and their effects in MRI of human subjects", "type" : "article-journal", "volume" : "65" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Collins and Wang, 2011)", "plainTextFormattedCitation" : "(Collins and Wang, 2011)", "previouslyFormattedCitation" : "(Collins and Wang, 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Collins and Wang, 2011) and the need for specific safety testing of any sequences used. Since there are choices in how the RF pulses required for MB sequences can be implemented, with varying effects on SAR ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.jmr.2013.02.002", "ISBN" : "1090-7807", "ISSN" : "10907807", "PMID" : "23473893", "abstract" : "The recent advancement of simultaneous multi-slice imaging using multiband excitation has dramatically reduced the scan time of the brain. The evolution of this parallel imaging technique began over a decade ago and through recent sequence improvements has reduced the acquisition time of multi-slice EPI by over ten fold. This technique has recently become extremely useful for (i) functional MRI studies improving the statistical definition of neuronal networks, and (ii) diffusion based fiber tractography to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences. \u00a9 2012 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Feinberg", "given" : "David A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Setsompop", "given" : "Kawin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Magnetic Resonance", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2013" ] ] }, "title" : "Ultra-fast MRI of the human brain with simultaneous multi-slice imaging", "type" : "article-journal" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Wong", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proceedings of the 20th Annual Meeting of ISMRM", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "2209", "publisher-place" : "Melbourne, Australia", "title" : "Optimized phase schedules for minimizing peak RF power in simultaneous multi-slice RF excitation pulses", "type" : "paper-conference" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1002/mrm.23152", "ISBN" : "1522-2594", "ISSN" : "07403194", "PMID" : "22009706", "abstract" : "This communication describes radiofrequency pulses capable of performing\\nspatially periodic excitation, inversion, and refocusing. The generation\\nof such pulses either by multiplication of existing radiofrequency\\npulses by a Dirac comb function or by means of Fourier series expansion\\nis described. Practical schemes for the implementation of such pulses\\nare given, and strategies for optimizing the pulse profile at fixed\\npulse duration are outlined. The pulses are implemented using a spin-echo\\nsequence. The power deposition is independent of the number of slices\\nacquired, and hence the power deposition per slice is considerably\\nreduced compared to multislice imaging. Excellent image quality is\\nobtained both in phantoms and in images of the human head. These\\npulses should find widespread application for multiplexed imaging,\\nin particular at high static magnetic field strengths and for pulse\\nsequences that have a high radiofrequency power deposition and could\\nlead to dramatic increases in scanning efficiency.", "author" : [ { "dropping-particle" : "", "family" : "Norris", "given" : "David G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Koopmans", "given" : "Peter J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Boyacio??lu", "given" : "Rasim", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barth", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magnetic Resonance in Medicine", "id" : "ITEM-3", "issue" : "5", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "1234-1240", "title" : "Power independent of number of slices (PINS) radiofrequency pulses for low-power simultaneous multislice excitation", "type" : "article-journal", "volume" : "66" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Feinberg and Setsompop, 2013; Norris et al., 2011; Wong, 2012)", "plainTextFormattedCitation" : "(Feinberg and Setsompop, 2013; Norris et al., 2011; Wong, 2012)", "previouslyFormattedCitation" : "(Feinberg and Setsompop, 2013; Norris et al., 2011; Wong, 2012)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Feinberg and Setsompop, 2013; Norris et al., 2011; Wong, 2012), it is important that MB implementations by different MR manufactures and software providers are individually tested before being used in human experiments.It is known that the use of MB can reduce image quality and consequently degrade the temporal stability of the signals acquired using EPI based sequences ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2014.10.027", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "ISSN" : "10959572", "PMID" : "25462696", "abstract" : "Echo planar imaging (EPI) is the MRI technique that is most widely used for blood oxygen level-dependent (BOLD) functional MRI (fMRI). Recent advances in EPI speed have been made possible with simultaneous multi-slice (SMS) methods which combine acceleration factors M from multiband (MB) radiofrequency pulses and S from simultaneous image refocusing (SIR) to acquire a total of N = S\u00d7. M images in one echo train, providing up to N times speed-up in total acquisition time over conventional EPI. We evaluated accelerations as high as N = 48 using different combinations of S and M which allow for whole brain imaging in as little as 100. ms at 3. T with a 32 channel head coil. The various combinations of acceleration parameters were evaluated by tSNR as well as BOLD contrast-to-noise ratio (CNR) and information content from checkerboard and movie clips in fMRI experiments. We found that at low acceleration factors (N. \u2264. 6), setting S=. 1 and varying M alone yielded the best results in all evaluation metrics, while at acceleration N = 8 the results were mixed using both S=. 1 and S=. 2 sequences. At higher acceleration factors (N > 8), using S=. 2 yielded maximal BOLD CNR and information content as measured by classification of movie clip frames. Importantly, we found significantly greater BOLD information content using relatively fast TRs in the range of 300. ms-600. ms compared to a TR of 2. s, suggesting that faster TRs capture more information per unit time in task based fMRI.", "author" : [ { "dropping-particle" : "", "family" : "Chen", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vu", "given" : "A. T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Xu", "given" : "J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Feinberg", "given" : "D. A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "452-459", "title" : "Evaluation of highly accelerated simultaneous multi-slice EPI for fMRI", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2015.08.056", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "ISSN" : "10959572", "PMID" : "26341029", "abstract" : "Functional magnetic resonance imaging (fMRI) studies that require high-resolution whole-brain coverage have long scan times that are primarily driven by the large number of thin slices acquired. Two-dimensional multiband echo-planar imaging (EPI) sequences accelerate the data acquisition along the slice direction and therefore represent an attractive approach to such studies by improving the temporal resolution without sacrificing spatial resolution. In this work, a 2D multiband EPI sequence was optimized for 1.5. mm isotropic whole-brain acquisitions at 3. T with 10 healthy volunteers imaged while performing simultaneous visual and motor tasks. The performance of the sequence was evaluated in terms of BOLD sensitivity and false-positive activation at multiband (MB) factors of 1, 2, 4, and 6, combined with in-plane GRAPPA acceleration of 2. \u00d7 (GRAPPA 2), and the two reconstruction approaches of Slice-GRAPPA and Split Slice-GRAPPA. Sensitivity results demonstrate significant gains in temporal signal-to-noise ratio (tSNR) and t-score statistics for MB 2, 4, and 6 compared to MB 1. The MB factor for optimal sensitivity varied depending on anatomical location and reconstruction method. When using Slice-GRAPPA reconstruction, evidence of false-positive activation due to signal leakage between simultaneously excited slices was seen in one instance, 35 instances, and 70 instances over the ten volunteers for the respective accelerations of MB 2. \u00d7. GRAPPA 2, MB 4. \u00d7. GRAPPA 2, and MB 6. \u00d7. GRAPPA 2. The use of Split Slice-GRAPPA reconstruction suppressed the prevalence of false positives significantly, to 1 instance, 5 instances, and 5 instances for the same respective acceleration factors. Imaging protocols using an acceleration factor of MB 2. \u00d7. GRAPPA 2 can be confidently used for high-resolution whole-brain imaging to improve BOLD sensitivity with very low probability for false-positive activation due to slice leakage. Imaging protocols using higher acceleration factors (MB 3 or MB 4. \u00d7. GRAPPA 2) can likely provide even greater gains in sensitivity but should be carefully optimized to minimize the possibility of false activations.", "author" : [ { "dropping-particle" : "", "family" : "Todd", "given" : "Nick", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "Steen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "Edward J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "Essa", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Flandin", "given" : "Guillaume", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Weiskopf", "given" : "Nikolaus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "32-42", "title" : "Evaluation of 2D multiband EPI imaging for high-resolution, whole-brain, task-based fMRI studies at 3T: Sensitivity and slice leakage artifacts", "type" : "article-journal", "volume" : "124" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Chen et al., 2015; Todd et al., 2016)", "plainTextFormattedCitation" : "(Chen et al., 2015; Todd et al., 2016)", "previouslyFormattedCitation" : "(Chen et al., 2015; Todd et al., 2016)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Chen et al., 2015; Todd et al., 2016). However, due to the ability of MB to shorten the TR, the increased temporal sampling can result in increased signal sensitivity per unit time as well as enhanced t-statistics of activation maps ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2015.08.056", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "ISSN" : "10959572", "PMID" : "26341029", "abstract" : "Functional magnetic resonance imaging (fMRI) studies that require high-resolution whole-brain coverage have long scan times that are primarily driven by the large number of thin slices acquired. Two-dimensional multiband echo-planar imaging (EPI) sequences accelerate the data acquisition along the slice direction and therefore represent an attractive approach to such studies by improving the temporal resolution without sacrificing spatial resolution. In this work, a 2D multiband EPI sequence was optimized for 1.5. mm isotropic whole-brain acquisitions at 3. T with 10 healthy volunteers imaged while performing simultaneous visual and motor tasks. The performance of the sequence was evaluated in terms of BOLD sensitivity and false-positive activation at multiband (MB) factors of 1, 2, 4, and 6, combined with in-plane GRAPPA acceleration of 2. \u00d7 (GRAPPA 2), and the two reconstruction approaches of Slice-GRAPPA and Split Slice-GRAPPA. Sensitivity results demonstrate significant gains in temporal signal-to-noise ratio (tSNR) and t-score statistics for MB 2, 4, and 6 compared to MB 1. The MB factor for optimal sensitivity varied depending on anatomical location and reconstruction method. When using Slice-GRAPPA reconstruction, evidence of false-positive activation due to signal leakage between simultaneously excited slices was seen in one instance, 35 instances, and 70 instances over the ten volunteers for the respective accelerations of MB 2. \u00d7. GRAPPA 2, MB 4. \u00d7. GRAPPA 2, and MB 6. \u00d7. GRAPPA 2. The use of Split Slice-GRAPPA reconstruction suppressed the prevalence of false positives significantly, to 1 instance, 5 instances, and 5 instances for the same respective acceleration factors. Imaging protocols using an acceleration factor of MB 2. \u00d7. GRAPPA 2 can be confidently used for high-resolution whole-brain imaging to improve BOLD sensitivity with very low probability for false-positive activation due to slice leakage. Imaging protocols using higher acceleration factors (MB 3 or MB 4. \u00d7. GRAPPA 2) can likely provide even greater gains in sensitivity but should be carefully optimized to minimize the possibility of false activations.", "author" : [ { "dropping-particle" : "", "family" : "Todd", "given" : "Nick", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "Steen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "Edward J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "Essa", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Flandin", "given" : "Guillaume", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Weiskopf", "given" : "Nikolaus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "32-42", "title" : "Evaluation of 2D multiband EPI imaging for high-resolution, whole-brain, task-based fMRI studies at 3T: Sensitivity and slice leakage artifacts", "type" : "article-journal", "volume" : "124" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Todd et al., 2016)", "plainTextFormattedCitation" : "(Todd et al., 2016)", "previouslyFormattedCitation" : "(Todd et al., 2016)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Todd et al., 2016). MB fMRI has been shown to be useful in a number of different applications since its conception only a few years ago, with the relative gains in sampling rate and voxel size that it can provide offsetting any signal quality degradation incurred ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2015.06.089", "ISBN" : "1095-9572\\r1053-8119", "ISSN" : "10959572", "PMID" : "26162554", "abstract" : "A multiband multi-echo (MBME) sequence is implemented and compared to a matched standard multi-echo (ME) protocol to investigate the potential improvement in sensitivity and spatial specificity at 7. T for resting state and task fMRI. ME acquisition is attractive because BOLD sensitivity is less affected by variation in T2*, and because of the potential for separating BOLD and non-BOLD signal components. MBME further reduces TR thus increasing the potential reduction in physiological noise. In this study we used FSL-FIX to clean ME and MBME resting state and task fMRI data (both 3.5. mm isotropic). After noise correction, the detection of resting state networks improves with more non-artifactual independent components being observed. Additional activation clusters for task data are discovered for MBME data (increased sensitivity) whereas existing clusters become more localized for resting state (improved spatial specificity). The results obtained indicate that MBME is superior to ME at high field strengths.", "author" : [ { "dropping-particle" : "", "family" : "Boyacio\u011flu", "given" : "Rasim", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schulz", "given" : "Jenni", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Koopmans", "given" : "Peter J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barth", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "352-361", "title" : "Improved sensitivity and specificity for resting state and task fMRI with multiband multi-echo EPI compared to multi-echo EPI at 7T", "type" : "article-journal", "volume" : "119" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/mrm.22361", "ISBN" : "1522-2594 (Electronic) 0740-3194 (Linking)", "PMID" : "20432285", "abstract" : "Parallel imaging in the form of multiband radiofrequency excitation, together with reduced k-space coverage in the phase-encode direction, was applied to human gradient echo functional MRI at 7 T for increased volumetric coverage and concurrent high spatial and temporal resolution. Echo planar imaging with simultaneous acquisition of four coronal slices separated by 44mm and simultaneous 4-fold phase-encoding undersampling, resulting in 16-fold acceleration and up to 16-fold maximal aliasing, was investigated. Task/stimulus-induced signal changes and temporal signal behavior under basal conditions were comparable for multiband and standard single-band excitation and longer pulse repetition times. Robust, whole-brain functional mapping at 7 T, with 2 x 2 x 2mm(3) (pulse repetition time 1.25 sec) and 1 x 1 x 2mm(3) (pulse repetition time 1.5 sec) resolutions, covering fields of view of 256 x 256 x 176 mm(3) and 192 x 172 x 176 mm(3), respectively, was demonstrated with current gradient performance.", "author" : [ { "dropping-particle" : "", "family" : "Moeller", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Olman", "given" : "C A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Strupp", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Harel", "given" : "N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magn Reson Med", "edition" : "2010/05/01", "id" : "ITEM-2", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Moeller, Steen\nYacoub, Essa\nOlman, Cheryl A\nAuerbach, Edward\nStrupp, John\nHarel, Noam\nUgurbil, Kamil\nCA 76535/CA/NCI NIH HHS/\nEB 000513/EB/NIBIB NIH HHS/\nP30 NS057091/NS/NINDS NIH HHS/\nP30 NS057091-01/NS/NINDS NIH HHS/\nP30 NS057091-05/NS/NINDS NIH HHS/\nP41 RR008079/RR/NCRR NIH HHS/\nP41 RR008079-175232/RR/NCRR NIH HHS/\nP41 RR008079-17S17728/RR/NCRR NIH HHS/\nP41 RR08079/RR/NCRR NIH HHS/\nR01 CA076535/CA/NCI NIH HHS/\nR01 CA076535-03/CA/NCI NIH HHS/\nR01 EB000331/EB/NIBIB NIH HHS/\nR01 EB000331-08/EB/NIBIB NIH HHS/\nR01 EB008645/EB/NIBIB NIH HHS/\nR01 EB008645-03/EB/NIBIB NIH HHS/\nR01 EB008645-04/EB/NIBIB NIH HHS/\nR01 MH070800/MH/NIMH NIH HHS/\nR01 MH070800-05/MH/NIMH NIH HHS/\nR44 EB005139-03/EB/NIBIB NIH HHS/\nMagn Reson Med. 2010 May;63(5):1144-53. doi: 10.1002/mrm.22361.", "page" : "1144-1153", "title" : "Multiband multislice GE-EPI at 7 tesla, with 16-fold acceleration using partial parallel imaging with application to high spatial and temporal whole-brain fMRI", "type" : "article-journal", "volume" : "63" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1371/journal.pone.0015710", "ISBN" : "1932-6203 (Electronic) 1932-6203 (Linking)", "PMID" : "21187930", "abstract" : "Echo planar imaging (EPI) is an MRI technique of particular value to neuroscience, with its use for virtually all functional MRI (fMRI) and diffusion imaging of fiber connections in the human brain. EPI generates a single 2D image in a fraction of a second; however, it requires 2-3 seconds to acquire multi-slice whole brain coverage for fMRI and even longer for diffusion imaging. Here we report on a large reduction in EPI whole brain scan time at 3 and 7 Tesla, without significantly sacrificing spatial resolution, and while gaining functional sensitivity. The multiplexed-EPI (M-EPI) pulse sequence combines two forms of multiplexing: temporal multiplexing (m) utilizing simultaneous echo refocused (SIR) EPI and spatial multiplexing (n) with multibanded RF pulses (MB) to achieve mxn images in an EPI echo train instead of the normal single image. This resulted in an unprecedented reduction in EPI scan time for whole brain fMRI performed at 3 Tesla, permitting TRs of 400 ms and 800 ms compared to a more conventional 2.5 sec TR, and 2-4 times reductions in scan time for HARDI imaging of neuronal fibertracks. The simultaneous SE refocusing of SIR imaging at 7 Tesla advantageously reduced SAR by using fewer RF refocusing pulses and by shifting fat signal out of the image plane so that fat suppression pulses were not required. In preliminary studies of resting state functional networks identified through independent component analysis, the 6-fold higher sampling rate increased the peak functional sensitivity by 60{%}. The novel M-EPI pulse sequence resulted in a significantly increased temporal resolution for whole brain fMRI, and as such, this new methodology can be used for studying non-stationarity in networks and generally for expanding and enriching the functional information.", "author" : [ { "dropping-particle" : "", "family" : "Feinberg", "given" : "D A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moeller", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "S M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auerbach", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ramanna", "given" : "S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gunther", "given" : "M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Glasser", "given" : "M F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "PLoS One", "edition" : "2010/12/29", "id" : "ITEM-3", "issue" : "12", "issued" : { "date-parts" : [ [ "2010" ] ] }, "note" : "Feinberg, David A\nMoeller, Steen\nSmith, Stephen M\nAuerbach, Edward\nRamanna, Sudhir\nGunther, Matthias\nGlasser, Matt F\nMiller, Karla L\nUgurbil, Kamil\nYacoub, Essa\n1R44NS063537/NS/NINDS NIH HHS/\n1R44NS073417/NS/NINDS NIH HHS/\n1U54MH091657-01/MH/NIMH NIH HHS/\nP30 NS057091/NS/NINDS NIH HHS/\nP41 RR08079/RR/NCRR NIH HHS/\nR01 EB000331/EB/NIBIB NIH HHS/\nS10 RR1395/RR/NCRR NIH HHS/\nPLoS One. 2010 Dec 20;5(12):e15710. doi: 10.1371/journal.pone.0015710.", "page" : "e15710", "title" : "Multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging", "type" : "article-journal", "volume" : "5" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1016/j.neuroimage.2015.02.052", "ISBN" : "0000000000000", "ISSN" : "10959572", "PMID" : "25743045", "abstract" : "The recent introduction of simultaneous multi-slice (SMS) acquisitions has enabled the acquisition of blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) data with significantly higher temporal sampling rates. In a parallel development, the use of multi-echo fMRI acquisitions in conjunction with a multi-echo independent component analysis (ME-ICA) approach has been introduced as a means to automatically distinguish functionally-related BOLD signal components from signal artifacts, with significant gains in sensitivity, statistical power, and specificity. In this work, we examine the gains that can be achieved with a combined approach in which data obtained with a multi-echo simultaneous multi-slice (MESMS) acquisition are analyzed with ME-ICA. We find that ME-ICA identifies significantly more BOLD-like components in the MESMS data as compared to data acquired with a conventional multi-echo single-slice acquisition. We demonstrate that the improved performance of MESMS derives from both an increase in the number of temporal samples and the enhanced ability to filter out high-frequency artifacts.", "author" : [ { "dropping-particle" : "", "family" : "Olafsson", "given" : "Valur", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kundu", "given" : "Prantik", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wong", "given" : "Eric C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bandettini", "given" : "Peter A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Liu", "given" : "Thomas T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-4", "issued" : { "date-parts" : [ [ "2015" ] ] }, "title" : "Enhanced identification of BOLD-like components with multi-echo simultaneous multi-slice (MESMS) fMRI and multi-echo ICA", "type" : "article-journal" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Boyacio\u011flu et al., 2015; Feinberg et al., 2010; Moeller et al., 2010; Olafsson et al., 2015)", "plainTextFormattedCitation" : "(Boyacio\u011flu et al., 2015; Feinberg et al., 2010; Moeller et al., 2010; Olafsson et al., 2015)", "previouslyFormattedCitation" : "(Boyacio\u011flu et al., 2015; Feinberg et al., 2010; Moeller et al., 2010; Olafsson et al., 2015)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Boyacio?lu et al., 2015; Feinberg et al., 2010; Moeller et al., 2010; Olafsson et al., 2015). Indeed, our own investigations showed that the variation in tSNR over subjects was far greater than the variation in tSNR between the sequences tested with different MB factors and slice acquisition schemes (Table 1). This suggests that the tSNR measures were dominated by physiological noise and anatomical variability rather than imaging sequence differences. Even when changes in tSNR within subjects between MB 2 and 3 were considered there no clear reduction was seen with increasing MB factor (Figure 3) in these data. By using MB factor = 3 with sparse slice acquisition we were able to maintain whole-head coverage whilst obtaining a 2.25s MR quiet period, within our 3s TR, in which to study EEG-BOLD coupling. Therefore the relative gain in quiet period time far outweighed effects on tSNR which were encountered. Benefits of MB fMRI for the simultaneous recording of high frequency EEG signals The presence of residual GAs in EEG data at frequencies above 20 Hz shows the necessity of an MR quiet period to provide the best SNR for studying beta and gamma band signals. These residual artefacts are present despite strict adherence to best-current practice acquisition and the implementation of hardware solutions (synchronisation (ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2006.04.231", "abstract" : "Investigating human brain function non-invasively by simultaneous EEG and fMRI measurements is gaining in popularity as more and better solutions to the inherent technical challenges emerge. We demonstrate the use of a commercially available frequency divider and phase-locking device for the purpose of synchronizing an MRI acquisition with a simultaneous recording of the EEG. Synchronization hugely improves the effectiveness of MRI artefact removal from the EEG signal by the common mean template subtraction method. It complements or substitutes post-processing techniques like filtering, thereby increasing the usable bandwidth of the EEG signal to about 150 Hz. This is important for covering the full range of human Gamma band activity. Similarly, synchronization eliminates the necessity for over-sampling of the EEG signal.", "author" : [ { "dropping-particle" : "", "family" : "Mandelkow", "given" : "H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Halder", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Boesiger", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brandeis", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "1120-1126", "title" : "Synchronization facilitates removal of MRI artefacts from concurrent EEG recordings and increases usable bandwidth", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/jmri.21277", "abstract" : "PURPOSE: To demonstrate that two methodological developments (synchronization of the MR scanner and electroencephalography [EEG] clocks and use of the scanner's vectorcardiogram [VCG]) improve the quality of EEG data recorded in combined EEG/functional MRI experiments in vivo. MATERIALS AND METHODS: EEG data were recorded using a 32-channel system, during simultaneous multislice EPI acquisition carried out on a 3 Tesla scanner. Recordings were made on three subjects in the resting state and on five subjects using a block paradigm involving visual stimulation with a 10-Hz flashing checkerboard. RESULTS: Gradient artifacts were significantly reduced in the EEG data recorded in vivo when synchronization and a TR equal to a multiple of the EEG clock period were used. This was evident from the greater attenuation of the signal at multiples of the slice acquisition frequency. Pulse artifact correction based on R-peak markers derived from the VCG was shown to offer a robust alternative to the conventionally used ECG-based method. Driven EEG responses at frequencies of up to 60 Hz due to the visual stimulus could be more readily detected in data recorded with EEG and MR scanner clock synchronization. CONCLUSION: Synchronization of the scanner and EEG clocks, along with VCG-based R-peak detection is advantageous in removing gradient and pulse artifacts in combined EEG/fMRI recordings. This approach is shown to allow the robust detection of high frequency driven activity in the EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morgan", "given" : "Paul S", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Magn Reson Imaging", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "607-616", "title" : "Improved artifact correction for combined electroencephalography/functional MRI by means of synchronization and use of vectorcardiogram recordings", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "manualFormatting" : "Mandelkow et al., 2006; Mullinger et al., 2008", "plainTextFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)", "previouslyFormattedCitation" : "(Mandelkow et al., 2006; Mullinger et al., 2008b)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Mandelkow et al., 2006; Mullinger et al., 2008) and optimal positioning (ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "S1053-8119(10)01281-4 [pii] 10.1016/j.neuroimage.2010.09.079", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "20932913", "abstract" : "Large artefacts that compromise EEG data quality are generated when electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are carried out concurrently. The gradient artefact produced by the time-varying magnetic field gradients is the largest of these artefacts. Although average artefact correction (AAS) and related techniques can remove the majority of this artefact, the need to avoid amplifier saturation necessitates the use of a large dynamic range and strong low-pass filtering in EEG recording. Any intrinsic reduction in the gradient artefact amplitude would allow data with a higher bandwidth to be acquired without amplifier saturation, thus increasing the frequency range of neuronal activity that can be investigated using combined EEG-fMRI. Furthermore, gradient artefact correction methods assume a constant artefact morphology over time, so their performance is compromised by subject movement. Since the resulting, residual gradient artefacts can easily swamp signals from brain activity, any reduction in their amplitude would be highly advantageous for simultaneous EEG-fMRI studies. The aim of this work was to investigate whether adjustment of the subject's axial position in the MRI scanner can reduce the amplitude of the induced gradient artefact, before and after artefact correction using AAS. The variation in gradient artefact amplitude as a function of the subject's axial position was first investigated in six subjects by applying gradient pulses along the three Cartesian axes. The results of this study showed that a significant reduction in the gradient artefact magnitude can be achieved by shifting the subject axially by 4 cm towards the feet relative to the standard subject position (nasion at iso-centre). In a further study, the 4-cm shift was shown to produce a 40{%} reduction in the RMS amplitude (and a 31{%} reduction in the range) of the gradient artefact generated during the execution of a standard multi-slice, EPI sequence. By picking out signals occurring at harmonics of the slice acquisition frequency, it was also shown that the 4-cm shift led to a 36{%} reduction in the residual gradient artefact after AAS. Functional and anatomical MR data quality is not affected by the 4-cm shift, as the head remains in the homogeneous region of the static magnet field and gradients.", "author" : [ { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yan", "given" : "W X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2010/10/12", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "note" : "Mullinger, Karen J\nYan, Winston X\nBowtell, Richard\nG0901321(46386)/Medical Research Council/United Kingdom\nG9900259/Medical Research Council/United Kingdom\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2011 Feb 1;54(3):1942-50. Epub 2010 Oct 13.", "page" : "1942-1950", "title" : "Reducing the gradient artefact in simultaneous EEG-fMRI by adjusting the subject's axial position", "type" : "article-journal", "volume" : "54" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Mullinger et al., 2011)", "manualFormatting" : "Mullinger et al., 2011", "plainTextFormattedCitation" : "(Mullinger et al., 2011)", "previouslyFormattedCitation" : "(Mullinger et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }Mullinger et al., 2011)) and beamforming post-processing ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "S1053-8119(08)01160-9 [pii] 10.1016/j.neuroimage.2008.10.047", "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19049883", "abstract" : "This paper investigates the application of source reconstruction methodologies to EEG data recorded in concurrent EEG/fMRI experiments at 7T. An EEG phantom containing a dipolar current source is described and used to investigate the accuracy of source localisation. Both dipole fitting and beamformer algorithms are shown to yield accurate locations for the dipole within the phantom. Source reconstruction methodologies are also shown to reduce significantly the level of interference in the recorded EEG, caused by the MR scanner. A comparison between beamformer and dipole fitting approaches is made and it is shown that, due to its adaptive weighting parameters, the beamformer provides better suppression of interference when compared to the dipole fit. In addition it is shown that, in the case of the beamformer, use of a high EEG channel density improves the level of interference reduction, and the ratio of measured signal to interference can be improved by a factor of approximately 1.6 if the number of EEG electrodes is increased from 32 to 64. The interference reduction properties of source localisation are shown theoretically, in simulation, and in phantom data. Finally, in-vivo experiments conducted at 7T show that effects in the gamma band can be recorded using simultaneous EEG/fMRI. These results are achieved by application of beamformer methodology to 64 channel EEG data.", "author" : [ { "dropping-particle" : "", "family" : "Brookes", "given" : "M J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vrba", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Geirsdottir", "given" : "G B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yan", "given" : "W X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stevenson", "given" : "C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "P G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2008/12/04", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2009" ] ] }, "note" : "Brookes, Matthew J\nVrba, Jiri\nMullinger, Karen J\nGeirsdottir, Gerda Bjork\nYan, Winston X\nStevenson, Claire M\nBowtell, Richard\nMorris, Peter G\nMedical Research Council/United Kingdom\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2009 Apr 1;45(2):440-52. Epub 2008 Nov 12.", "page" : "440-452", "title" : "Source localisation in concurrent EEG/fMRI: applications at 7T", "type" : "article-journal", "volume" : "45" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2007.12.030", "abstract" : "The simultaneous application of functional MRI and EEG represents an attractive, non-invasive technique for the combined measurement of electrical and haemodynamic activity in the human brain. Simultaneous EEG/fMRI provides a brain imaging modality with millimeter spatial accuracy, and millisecond temporal resolution. However, simultaneously acquired measurements are difficult due to the artifacts that are induced in the EEG by both the temporally varying field gradients used in MRI, and also blood flow effects. In this paper we apply an EEG beamformer spatial filter to EEG data recorded simultaneously with fMRI. We show, using this technique, that it is possible to localise accurately electrical effects in the brain, and that the localisation of driven oscillatory responses in the human visual cortex are spatially co-incident with the fMRI BOLD response. We also show how the beamformer can be used to extract timecourses of electrical activity from areas of interest in the brain. Such timecourses have millisecond time resolution. Finally, we show that in addition to source localisation, the beamformer spatial filter acts to reject interference in EEG signals, thus increasing the effective signal to noise ratio of electrical measurements. We show that the EEG-beamformer can eliminate effectively the ballistocardiogram artifact as well as residual gradient artifacts that remain in EEG data following correction using averaged artifact subtraction techniques.", "author" : [ { "dropping-particle" : "", "family" : "Brookes", "given" : "Matthew J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stevenson", "given" : "Claire M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "Peter G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "1090-1104", "title" : "Simultaneous EEG source localisation and artifact rejection during concurrent fMRI by means of spatial filtering", "type" : "article-journal", "volume" : "40" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Brookes et al., 2009, 2008)", "plainTextFormattedCitation" : "(Brookes et al., 2009, 2008)", "previouslyFormattedCitation" : "(Brookes et al., 2009, 2008)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Brookes et al., 2009, 2008) which are all designed to minimise the residual GAs. Whilst the magnitude of the residual GA appears to increase with frequency (Figure 6), it is actually relatively constant across the frequency bands above 20 Hz (Figure S4c&d), but the relative contribution of the GA to the overall signal is increased due to the decrease in the amplitude of the underlying neuronal activity at higher frequencies resulting in Figure S4e&f. These residual artefacts are likely to be caused by sub-millimetre movements of the subject’s head during data acquisition causing small changes in the GA profile, preventing perfect correction by template subtraction methods ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "ISBN" : "1095-9572 (Electronic) 1053-8119 (Linking)", "PMID" : "19385014", "abstract" : "Implementation of concurrent functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) recording results in the generation of large artefacts that can compromise the quality of EEG data. While much effort has been devoted towards studying the temporal variation of the artefact waveforms produced by time-varying magnetic field gradients, the spatial variation of the artefact voltage across EEG leads has not previously been investigated in any depth. The aim of this work is to develop an improved understanding of the spatial characteristics of the gradient artefacts and the mechanism which underlies their generation. This paper therefore presents physical models of the artefacts produced by the temporally-varying magnetic field gradients required for MRI. Novel analytic expressions for the artefact voltage that account for realistic shifts and rotations of the human head were calculated from electromagnetic theory, assuming a spherical, homogeneous head and longitudinal wirepaths for the EEG cap. These were then corroborated by comparison with numerical simulations using actual EEG wirepaths and with experimental measurements on an agar phantom and human head. The numerical simulations produced accurate reproductions of experimentally measured spatial patterns for both the spherical phantom and human head in a variety of orientations and gradient fields; correlation coefficients were as high as 0.98 for the phantom and 0.95 for the human head. Furthermore, it was determined that artefact voltages for both longitudinal and transverse gradients could be decreased by adjusting the subject's axial position with respect to the gradient coils. The accuracy of the modelled spatial maps along with the ability to model gradient artefacts for any given head orientation are a step towards developing improved artefact correction algorithms that incorporate motion tracking of the subject and selective filtering based on calculated spatial artefact templates, leading to greater fidelity in simultaneous EEG/fMRI data.", "author" : [ { "dropping-particle" : "", "family" : "Yan", "given" : "W X", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "K J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brookes", "given" : "M J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "edition" : "2009/04/23", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2009" ] ] }, "note" : "Yan, Winston X\nMullinger, Karen J\nBrookes, Matt J\nBowtell, Richard\nG9900259/Medical Research Council/United Kingdom\nResearch Support, Non-U.S. Gov't\nUnited States\nNeuroImage\nNeuroimage. 2009 Jun;46(2):459-71.", "page" : "459-471", "title" : "Understanding gradient artefacts in simultaneous EEG/fMRI", "type" : "article-journal", "volume" : "46" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.mri.2007.03.005", "ISBN" : "0730-725X (Print)\\r0730-725X (Linking)", "ISSN" : "0730725X", "PMID" : "17462844", "abstract" : "Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has become a widely used application in spite of EEG perturbations due to electromagnetic interference in the MR environment. The most prominent and disturbing artifacts in the EEG are caused by the alternating magnetic fields (gradients) of the MR scanner. Different methods for gradient artifact correction have been developed. Here we propose an approach for the systematic evaluation and comparison of these gradient artifact correction methods. Exemplarily, we evaluate different algorithms all based on artifact template subtraction - the currently most established means of gradient artifact removal. We introduce indices for the degree of gradient artifact reduction and physiological signal preservation. The combination of both indices was used as a measure for the overall performance of gradient artifact removal and was shown to be useful in identifying problems during artifact removal. We demonstrate that the evaluation as proposed here allows to reveal frequency-band specific performance differences among the algorithms. This emphasizes the importance of carefully selecting the artifact correction method appropriate for the respective case. \u00a9 2007 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Ritter", "given" : "Petra", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Becker", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Graefe", "given" : "Christine", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Villringer", "given" : "Arno", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magnetic Resonance Imaging", "id" : "ITEM-2", "issue" : "6", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "923-932", "title" : "Evaluating gradient artifact correction of EEG data acquired simultaneously with fMRI", "type" : "article-journal", "volume" : "25" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Ritter et al., 2007; Yan et al., 2009)", "plainTextFormattedCitation" : "(Ritter et al., 2007; Yan et al., 2009)", "previouslyFormattedCitation" : "(Ritter et al., 2007; Yan et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Ritter et al., 2007; Yan et al., 2009). Given that such small head movements cannot be eliminated during acquisition and the current lack of a post-processing method to completely remove residual GAs from the EEG data, despite considerable effort by a number of groups ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.06.022", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19539035", "abstract" : "Although solutions for imaging-artifact correction in simultaneous EEG-fMRI are improving, residual artifacts after correction still considerably affect the EEG spectrum in the ultrafast frequency band above 100 Hz. Yet this band contains subtle but valuable physiological signatures such as fast gamma oscillations or evoked high-frequency (600 Hz) bursts related to spiking of thalamocortical and cortical neurons. Here we introduce a simultaneous EEG-fMRI approach that integrates hard and software modifications for continuous acquisition of ultrafast EEG oscillations during fMRI. Our approach is based upon and extends the established method of averaged artifact subtraction (AAS). Particularly for recovery of ultrahigh-frequency EEG signatures, AAS requires invariantly sampled and constant imaging-artifact waveforms to achieve optimal imaging-artifact correction. Consequently, we adjusted our acquisition setup such that both physiological ultrahigh-frequency EEG and invariantly sampled imaging artifacts were captured. In addition, we extended the AAS algorithm to cope with other, non-sampling related sources of imaging-artifact variations such as subject movements. A cascaded principal component analysis finally removed remaining imaging-artifact residuals. We provide a detailed evaluation of averaged ultrahigh-frequency signals and unaveraged broadband EEG spectra up to 1 kHz. Evoked nanovolt-sized high-frequency bursts were successfully recovered during periods of MR data acquisition afflicted by imaging artifacts in the millivolt range. Compared to periods without imaging artifacts they exhibited the same mean amplitudes, latencies and waveforms and a signal-to-noise ratio of 72%. Furthermore we identified consistent dipole sources. In conclusion, ultrafast EEG oscillations can be continuously monitored during fMRI using the proposed approach. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Freyer", "given" : "Frank", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Becker", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Anami", "given" : "Kimitaka", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Curio", "given" : "Gabriel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Villringer", "given" : "Arno", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ritter", "given" : "Petra", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "94-108", "title" : "Ultrahigh-frequency EEG during fMRI: Pushing the limits of imaging-artifact correction", "type" : "article-journal", "volume" : "48" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2016.05.003", "ISBN" : "1053-8119", "ISSN" : "10959572", "PMID" : "27157789", "abstract" : "The simultaneous acquisition of electroencephalography and functional magnetic resonance imaging (EEG-fMRI) is a multimodal technique extensively applied for mapping the human brain. However, the quality of EEG data obtained within the MRI environment is strongly affected by subject motion due to the induction of voltages in addition to artefacts caused by the scanning gradients and the heartbeat. This has limited its application in populations such as paediatric patients or to study epileptic seizure onset. Recent work has used a Moir??-phase grating and a MR-compatible camera to prospectively update image acquisition and improve fMRI quality (prospective motion correction: PMC). In this study, we use this technology to retrospectively reduce the spurious voltages induced by motion in the EEG data acquired inside the MRI scanner, with and without fMRI acquisitions. This was achieved by modelling induced voltages from the tracking system motion parameters; position and angles, their first derivative (velocities) and the velocity squared. This model was used to remove the voltages related to the detected motion via a linear regression. Since EEG quality during fMRI relies on a temporally stable gradient artefact (GA) template (calculated from averaging EEG epochs matched to scan volume or slice acquisition), this was evaluated in sessions both with and without motion contamination, and with and without PMC. We demonstrate that our approach is capable of significantly reducing motion-related artefact with a magnitude of up to 10??mm of translation, 6?? of rotation and velocities of 50??mm/s, while preserving physiological information. We also demonstrate that the EEG-GA variance is not increased by the gradient direction changes associated with PMC. Provided a scan slice-based GA template is used (rather than a scan volume GA template) we demonstrate that EEG variance during motion can be supressed towards levels found when subjects are still. In summary, we show that PMC can be used to dramatically improve EEG quality during large amplitude movements, while benefiting from previously reported improvements in fMRI quality, and does not affect EEG data quality in the absence of large amplitude movements.", "author" : [ { "dropping-particle" : "", "family" : "Maziero", "given" : "Danilo", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Velasco", "given" : "Tonicarlo R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hunt", "given" : "Nigel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Payne", "given" : "Edwin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Lemieux", "given" : "Louis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Salmon", "given" : "Carlos E G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Carmichael", "given" : "David W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "13-27", "title" : "Towards motion insensitive EEG-fMRI: Correcting motion-induced voltages and gradient artefact instability in EEG using an fMRI prospective motion correction (PMC) system", "type" : "article-journal", "volume" : "138" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.01.024", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19349230", "abstract" : "In this work we introduce a new algorithm to correct the imaging artefacts in the EEG signal measured during fMRI acquisition. The correction techniques proposed so far cannot optimally represent transitions, i.e. when abrupt changes of the artefact properties due to head movements occur. The algorithm developed here takes the head movement parameters from the fMRI signal into account to calculate adequate EEG artefact templates and subsequently correct the distorted EEG data. The data reported in this work demonstrate that the realignment parameter-informed algorithm outperforms the commonly used moving average algorithm if head movements occur. The superiority is reflected by comparing the residual variance after artefact correction with either method. The residual variance is lower around head-movements that exceed head deflections of about 1 mm when applying the realignment parameter-informed algorithm. Additionally, the signal to noise ratio of a surrogate event-related potential (ERP) increased by 10-40% for head displacements larger than 1 mm. The algorithm developed here is particularly suited for studies where head movements of the subject cannot be prevented as in studies with patients, children, or during sleep. Furthermore, the enhanced signal to noise ratio of a single trial ERP indicates the power of the presented algorithm for single trial ERP-fMRI studies in which EEG signal quality is a critical factor. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sch\u00f6nfelder", "given" : "Vinzenz H.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Specht", "given" : "Karsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Nordby", "given" : "Helge", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hugdahl", "given" : "Kenneth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-3", "issue" : "4", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "1144-1150", "title" : "Realignment parameter-informed artefact correction for simultaneous EEG-fMRI recordings", "type" : "article-journal", "volume" : "45" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1016/j.neuroimage.2007.12.030", "abstract" : "The simultaneous application of functional MRI and EEG represents an attractive, non-invasive technique for the combined measurement of electrical and haemodynamic activity in the human brain. Simultaneous EEG/fMRI provides a brain imaging modality with millimeter spatial accuracy, and millisecond temporal resolution. However, simultaneously acquired measurements are difficult due to the artifacts that are induced in the EEG by both the temporally varying field gradients used in MRI, and also blood flow effects. In this paper we apply an EEG beamformer spatial filter to EEG data recorded simultaneously with fMRI. We show, using this technique, that it is possible to localise accurately electrical effects in the brain, and that the localisation of driven oscillatory responses in the human visual cortex are spatially co-incident with the fMRI BOLD response. We also show how the beamformer can be used to extract timecourses of electrical activity from areas of interest in the brain. Such timecourses have millisecond time resolution. Finally, we show that in addition to source localisation, the beamformer spatial filter acts to reject interference in EEG signals, thus increasing the effective signal to noise ratio of electrical measurements. We show that the EEG-beamformer can eliminate effectively the ballistocardiogram artifact as well as residual gradient artifacts that remain in EEG data following correction using averaged artifact subtraction techniques.", "author" : [ { "dropping-particle" : "", "family" : "Brookes", "given" : "Matthew J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stevenson", "given" : "Claire M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "Peter G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bowtell", "given" : "Richard", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-4", "issue" : "3", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "1090-1104", "title" : "Simultaneous EEG source localisation and artifact rejection during concurrent fMRI by means of spatial filtering", "type" : "article-journal", "volume" : "40" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Brookes et al., 2008; Freyer et al., 2009; Maziero et al., 2016; Moosmann et al., 2009)", "plainTextFormattedCitation" : "(Brookes et al., 2008; Freyer et al., 2009; Maziero et al., 2016; Moosmann et al., 2009)", "previouslyFormattedCitation" : "(Brookes et al., 2008; Freyer et al., 2009; Maziero et al., 2016; Moosmann et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Brookes et al., 2008; Freyer et al., 2009; Maziero et al., 2016; Moosmann et al., 2009), the merit of an MR quiet period, that enables the study of higher frequency neuronal activity unadulterated by concurrent fMRI acquisition, is clear.Indeed, using a sparse MR sequence incorporating quiet periods has previously been implemented to allow the study of gamma band activity during fMRI ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1093/schbul/sbv092", "ISBN" : "4940741059805", "ISSN" : "17451701", "PMID" : "26163477", "abstract" : "Objectives. Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). Methods. EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG- informed fMRI). Results. A gamma-band\u2013specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. Conclusions. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeat- edly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia.", "author" : [ { "dropping-particle" : "", "family" : "Leicht", "given" : "Gregor", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vauth", "given" : "Sebastian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Polomac", "given" : "Nenad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Andreou", "given" : "Christina", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rauh", "given" : "Jonas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mu??mann", "given" : "Marius", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karow", "given" : "Anne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mulert", "given" : "Christoph", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Schizophrenia Bulletin", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "239-249", "title" : "EEG-Informed fMRI Reveals a Disturbed Gamma-Band-Specific Network in Subjects at High Risk for Psychosis", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.10.058", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19878729", "abstract" : "Oscillations in the gamma-band frequency range have been described to be more closely connected to hemodynamic changes as assessed with functional magnetic resonance imaging (fMRI) than other aspects of neuronal activity. In addition, gamma-band oscillations have attracted much interest during the last few years since they are thought to play a crucial role in many aspects of brain function related to perception and cognition. It was the aim of the present simultaneous EEG-fMRI study to identify brain regions specifically involved in the generation of the auditory gamma-band response (GBR) using single-trial coupling of EEG and fMRI. Ten healthy subjects participated in this study. Three different runs of an auditory choice reaction task with increasing difficulty were performed. Brain activity was recorded simultaneously with high density EEG (61 channels) and fMRI (1.5 T). BOLD correlates of the GBR have been predicted using the single-trial amplitude of the GBR. Reaction times (p < 0.001), error rates (p < 0.05) and self-ratings of task difficulty and effort demands (p < 0.001) were related to the level of difficulty in the task. In addition, we found a significant influence of task difficulty on the amplitude of the GBR at Cz (p < 0.05). Using single-trial coupling of EEG and fMRI GBR-specific activations were found only in the auditory cortex, the thalamus and the anterior cingulate cortex (ACC) in the most difficult run. Single-trial coupling might be a useful method in order to increase our knowledge about the functional neuroanatomy of \"neural ensembles\" coupled by 40 Hz oscillations. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Mulert", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hepp", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirsch", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Reiser", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "J\u00e4ger", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moller", "given" : "H. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McCarley", "given" : "R. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2238-2247", "title" : "Single-trial coupling of the gamma-band response and the corresponding BOLD signal", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-3", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "previouslyFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011). We have extended these previous works by showing that beta and gamma band activity from motor cortex can be measured in the MRI environment. We observed an ERS of gamma band power during the abduction movements compared with rest (Figs 5a and 6a&b) localised to cM1, in close agreement with previous MEG studies ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2008.02.032", "ISBN" : "1053-8119", "ISSN" : "10538119", "PMID" : "18424182", "abstract" : "Electrocorticographic (ECoG) recordings obtained using intracranially implanted electrodes in epilepsy patients indicate that high gamma band (HGB) activity of sensorimotor cortex is focally increased during voluntary movement. These movement related HGB modulations may play an important role in sensorimotor cortex function. It is however currently not clear to what extent this type of neural activity can be detected using non-invasive electroencephalography (EEG) and how similar HGB responses in healthy human subjects are to those observed in epilepsy patients. Using the same arm reaching task, we have investigated spectral power changes both in intracranial ECoG recordings in epilepsy patients and in non-invasive EEG recordings optimized for detecting HGB activity in healthy subjects. Our results show a common HGB response pattern both in ECoG and EEG recorded above the sensorimotor cortex contralateral to the side of arm movement. In both cases, HGB activity increased around movement onset in the 60-90 Hz range and became most pronounced at reaching movement end. Additionally, we found EEG HGB activity above the frontal midline possibly generated by the anterior supplementary motor area (SMA), a region that was however not covered by the intracranial electrodes used in the present study. In summary, our findings show that HGB activity from human sensorimotor cortex can be non-invasively detected in healthy subjects using EEG, opening a new perspective for investigating the role of high gamma range neuronal activity both in function and dysfunction of the human cortical sensorimotor network. \u00a9 2008 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Ball", "given" : "Tonio", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Demandt", "given" : "Evariste", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mutschler", "given" : "Isabella", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Neitzel", "given" : "Eva", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mehring", "given" : "Carsten", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vogt", "given" : "Klaus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Aertsen", "given" : "Ad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schulze-Bonhage", "given" : "Andreas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "302-310", "title" : "Movement related activity in the high gamma range of the human EEG", "type" : "article-journal", "volume" : "41" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.expneurol.2012.08.030", "ISBN" : "1090-2430 (Electronic)\\n0014-4886 (Linking)", "ISSN" : "00144886", "PMID" : "22981841", "abstract" : "The human sensorimotor cortex demonstrates a variety of oscillatory activity that is strongly modulated by movement and somatosensory input. Studies using scalp EEG and intracranial electrical recordings have provided much of our current knowledge regarding the frequency and temporal specificity of these sensorimotor rhythms and their relationship to various movement parameters, however with limitations in identifying the underlying neural sources, and the variety of motor behaviors that can be studied, respectively. Magnetoencephalography (MEG) recordings, combined with spatial filtering source reconstruction methods, provide an ideal non-invasive method for the localization of sensorimotor rhythms and for describing their precise time course during a variety of motor tasks. This review describes the application of MEG to the study of oscillatory activity in the human sensorimotor cortex, including advances in localization techniques and recent contributions of MEG to our understanding of the functional role of these oscillations in both adult and developmental populations. \u00a9 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Cheyne", "given" : "Douglas Owen", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Experimental Neurology", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "27-39", "title" : "MEG studies of sensorimotor rhythms: A review", "type" : "article", "volume" : "245" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.08.041", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19715762", "abstract" : "High gamma (HG) power changes during motor activity, especially at frequencies above 70\u00a0Hz, play an important role in functional cortical mapping and as control signals for BCI (brain-computer interface) applications. Most studies of HG activity have used ECoG (electrocorticography) which provides high-quality spatially localized signals, but is an invasive method. Recent studies have shown that non-invasive modalities such as EEG and MEG can also detect task-related HG power changes. We show here that a 27 channel EEG (electroencephalography) montage provides high-quality spatially localized signals non-invasively for HG frequencies ranging from 83 to 101\u00a0Hz. We used a generic head model, a weighted minimum norm least squares (MNLS) inverse method, and a self-paced finger movement paradigm. The use of an inverse method enables us to map the EEG onto a generic cortex model. We find the HG activity during the task to be well localized in the contralateral motor area. We find HG power increases prior to finger movement, with average latencies of 462\u00a0ms and 82\u00a0ms before EMG (electromyogram) onset. We also find significant phase-locking between contra- and ipsilateral motor areas over a similar HG frequency range; here the synchronization onset precedes the EMG by 400\u00a0ms. We also compare our results to ECoG data from a similar paradigm and find EEG mapping and ECoG in good agreement. Our findings demonstrate that mapped EEG provides information on two important parameters for functional mapping and BCI which are usually only found in HG of ECoG signals: spatially localized power increases and bihemispheric phase-locking. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Scherer", "given" : "R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sorensen", "given" : "L. B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-3", "issue" : "1", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "930-938", "publisher" : "Elsevier Inc.", "title" : "High gamma mapping using EEG", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1152/jn.00607.2010", "ISBN" : "1522-1598 (Electronic)\\r0022-3077 (Linking)", "ISSN" : "0022-3077", "PMID" : "20884762", "abstract" : "Muthukumaraswamy SD. Functional properties of human primary motor cortex gamma oscillations. J Neurophysiol 104: 2873-2885, 2010. First published September 8, 2010; doi:10.1152/jn.00607.2010. Gamma oscillations in human primary motor cortex (M1) have been described in human electrocorticographic and noninvasive magnetoencephalographic (MEG)/electroencephalographic recordings, yet their functional significance within the sensorimotor system remains unknown. In a set of four MEG experiments described here a number of properties of these oscillations are elucidated. First, gamma oscillations were reliably localized by MEG in M1 and reached peak amplitude 137 ms after electromyographic onset and were not affected by whether movements were cued or self-paced. Gamma oscillations were found to be stronger for larger movements but were absent during the sustained part of isometric movements, with no finger movement or muscle shortening. During repetitive movement sequences gamma oscillations were greater for the first movement of a sequence. Finally, gamma oscillations were absent during passive shortening of the finger compared with active contractions sharing similar kinematic properties demonstrating that M1 oscillations are not simply related to somatosensory feedback. This combined pattern of results is consistent with gamma oscillations playing a role in a relatively late stage of motor control, encoding information related to limb movement rather than to muscle contraction.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neurophysiology", "id" : "ITEM-4", "issue" : "5", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2873-2885", "title" : "Functional Properties of Human Primary Motor Cortex Gamma Oscillations", "type" : "article-journal", "volume" : "104" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Ball et al., 2008; Cheyne, 2013; Darvas et al., 2010; Muthukumaraswamy, 2010)", "plainTextFormattedCitation" : "(Ball et al., 2008; Cheyne, 2013; Darvas et al., 2010; Muthukumaraswamy, 2010)", "previouslyFormattedCitation" : "(Ball et al., 2008; Cheyne, 2013; Darvas et al., 2010; Muthukumaraswamy, 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Ball et al., 2008; Cheyne, 2013; Darvas et al., 2010; Muthukumaraswamy, 2010). This gamma band response was accompanied by a decrease (ERD) in beta band power (Figs 5b and 6c&d) which was observed in bilateral M1, in agreement with previous studies collected outside an MRI environment ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.11.045", "abstract" : "There is increasing interest in the role gamma oscillations ( approximately 40 Hz) play in visual information processing. Despite this interest, and in contrast to the classically studied visual evoked potential, surprisingly little is known about the intra-individual repeatability of induced gamma oscillations. Similarly, little is known about inter-individual variability in terms of gamma oscillation frequency, bandwidth and amplitude with no extant normative data for these parameters. The purpose of the current study was therefore to examine the repeatability of visual gamma oscillations and to provide the first normative data on them. Our results demonstrate that evoked responses were highly repeatable across recording sessions whereas for induced visual gamma oscillations a large amount of inter-individual variability existed in terms of frequency, bandwidth and amplitude. However, these parameters and the general morphology of the gamma band response were stable within the same individuals for at least 4 weeks. The high degree of individual variability in gamma oscillations for gamma amplitude, bandwidth and frequency suggests that between-group studies on gamma oscillations will be difficult, requiring relatively large amounts of data to detect differences. However, the high degree of individual repeatability for gamma oscillation frequency, bandwidth and amplitude suggests that these dependent variables will be well suited for repeated-measure designs such as pharmacological studies. A number of individuals are described which show clear evoked responses yet a near absence of gamma oscillations and vice versa suggesting dissociations between the generative mechanisms of these responses. Our results also demonstrate that gamma frequency tends to decline with age and is positively correlated with the thickness of the pericalcarine cortex.", "author" : [ { "dropping-particle" : "", "family" : "Muthukumaraswamy", "given" : "Suresh D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Singh", "given" : "Krish D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Swettenham", "given" : "Jennifer B", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Derek K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "3349-3357", "title" : "Visual gamma oscillations and evoked responses: variability, repeatability and structural MRI correlates", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Jurkiewicz", "given" : "M T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaetz", "given" : "W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bostan", "given" : "A C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cheyne", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuroimage", "id" : "ITEM-2", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "1281-1289", "title" : "Post-movement beta rebound is generated in motor cortex: Evidence from neuromagnetic recordings", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1097/WNP.0b013e3182872f40", "ISBN" : "2122633255", "ISSN" : "1537-1603", "PMID" : "23733096", "abstract" : "Power changes in the beta frequency range (17-25 Hz) in the human motor and premotor areas during action observation have been associated with the mirror neuron system and have been studied extensively. These changes mimic motor activity during actual motion execution, albeit reduced in strength. Recent noninvasive (EEG/magnetoencephalography) and invasive studies (electrocorticography) have shown that during actual motion, beta power changes are accompanied by highly localized changes in the high gamma band (70-100 Hz). In this study, we investigate, using 27-channel EEG in combination with a generic head model and a cortical mapping algorithm, whether such high gamma changes are also present during motion observation. Subjects were presented with a 2.7-second video of a moving hand, contrasted with a video of moving scenery of equal length. Our results show nonlateralized beta band decrease in power in response to the moving hand versus the response to the moving scenery. We also find significant increase in high gamma power. However, unlike the beta band response, increases in this band are lateralized, with a preference for the hemisphere of the dominant hand.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "Felix", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "Rajesh P N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Murias", "given" : "Micheal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society", "id" : "ITEM-3", "issue" : "3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "299-307", "title" : "Localized high gamma motor oscillations respond to perceived biologic motion.", "type" : "article-journal", "volume" : "30" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Darvas et al., 2013; Jurkiewicz et al., 2006; Muthukumaraswamy et al., 2010)", "plainTextFormattedCitation" : "(Darvas et al., 2013; Jurkiewicz et al., 2006; Muthukumaraswamy et al., 2010)", "previouslyFormattedCitation" : "(Darvas et al., 2013; Jurkiewicz et al., 2006; Muthukumaraswamy et al., 2010)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Darvas et al., 2013; Jurkiewicz et al., 2006; Muthukumaraswamy et al., 2010). Interestingly, previous invasive and non-invasive electrophysiological recordings have shown that the gamma ERS is more spatially focal to cM1 than the beta ERD ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1523/JNEUROSCI.3886-06.2007", "ISBN" : "0270-6474", "ISSN" : "0270-6474", "PMID" : "17329441", "abstract" : "In the first large study of its kind, we quantified changes in electrocorticographic signals associated with motor movement across 22 subjects with subdural electrode arrays placed for identification of seizure foci. Patients underwent a 5-7 d monitoring period with array placement, before seizure focus resection, and during this time they participated in the study. An interval-based motor-repetition task produced consistent and quantifiable spectral shifts that were mapped on a Talairach-standardized template cortex. Maps were created independently for a high-frequency band (HFB) (76-100 Hz) and a low-frequency band (LFB) (8-32 Hz) for several different movement modalities in each subject. The power in relevant electrodes consistently decreased in the LFB with movement, whereas the power in the HFB consistently increased. In addition, the HFB changes were more focal than the LFB changes. Sites of power changes corresponded to stereotactic locations in sensorimotor cortex and to the results of individual clinical electrical cortical mapping. Sensorimotor representation was found to be somatotopic, localized in stereotactic space to rolandic cortex, and typically followed the classic homunculus with limited extrarolandic representation.", "author" : [ { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leuthardt", "given" : "E. C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schalk", "given" : "Gerwin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P. N.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Anderson", "given" : "N. R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moran", "given" : "D. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "J. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neuroscience", "id" : "ITEM-1", "issue" : "9", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "2424-2432", "title" : "Spectral Changes in Cortical Surface Potentials during Motor Movement", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1097/WNP.0b013e3182872f40", "ISBN" : "2122633255", "ISSN" : "1537-1603", "PMID" : "23733096", "abstract" : "Power changes in the beta frequency range (17-25 Hz) in the human motor and premotor areas during action observation have been associated with the mirror neuron system and have been studied extensively. These changes mimic motor activity during actual motion execution, albeit reduced in strength. Recent noninvasive (EEG/magnetoencephalography) and invasive studies (electrocorticography) have shown that during actual motion, beta power changes are accompanied by highly localized changes in the high gamma band (70-100 Hz). In this study, we investigate, using 27-channel EEG in combination with a generic head model and a cortical mapping algorithm, whether such high gamma changes are also present during motion observation. Subjects were presented with a 2.7-second video of a moving hand, contrasted with a video of moving scenery of equal length. Our results show nonlateralized beta band decrease in power in response to the moving hand versus the response to the moving scenery. We also find significant increase in high gamma power. However, unlike the beta band response, increases in this band are lateralized, with a preference for the hemisphere of the dominant hand.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "Felix", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "Rajesh P N", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Murias", "given" : "Micheal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "299-307", "title" : "Localized high gamma motor oscillations respond to perceived biologic motion.", "type" : "article-journal", "volume" : "30" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Darvas et al., 2013; Miller et al., 2007)", "plainTextFormattedCitation" : "(Darvas et al., 2013; Miller et al., 2007)", "previouslyFormattedCitation" : "(Darvas et al., 2013; Miller et al., 2007)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Darvas et al., 2013; Miller et al., 2007), which was also observed in our data. In addition to the difference in the spatial localisation of the gamma/beta responses, we also observed different temporal profiles between the spectral responses from these locations. The gamma ERS covered a relatively large frequency range (~50-80Hz) and, whilst it could be seen for the entire movement period, it was strongest at initial movement onset (i.e. 0-0.5s Fig 6a). The beta ERD was found to be much stronger and was present consistently throughout the entire movement period. Together these differences in spatial location and temporal response profile suggest different neuronal populations are driving these two responses, in line with previous findings ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.08.041", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19715762", "abstract" : "High gamma (HG) power changes during motor activity, especially at frequencies above 70\u00a0Hz, play an important role in functional cortical mapping and as control signals for BCI (brain-computer interface) applications. Most studies of HG activity have used ECoG (electrocorticography) which provides high-quality spatially localized signals, but is an invasive method. Recent studies have shown that non-invasive modalities such as EEG and MEG can also detect task-related HG power changes. We show here that a 27 channel EEG (electroencephalography) montage provides high-quality spatially localized signals non-invasively for HG frequencies ranging from 83 to 101\u00a0Hz. We used a generic head model, a weighted minimum norm least squares (MNLS) inverse method, and a self-paced finger movement paradigm. The use of an inverse method enables us to map the EEG onto a generic cortex model. We find the HG activity during the task to be well localized in the contralateral motor area. We find HG power increases prior to finger movement, with average latencies of 462\u00a0ms and 82\u00a0ms before EMG (electromyogram) onset. We also find significant phase-locking between contra- and ipsilateral motor areas over a similar HG frequency range; here the synchronization onset precedes the EMG by 400\u00a0ms. We also compare our results to ECoG data from a similar paradigm and find EEG mapping and ECoG in good agreement. Our findings demonstrate that mapped EEG provides information on two important parameters for functional mapping and BCI which are usually only found in HG of ECoG signals: spatially localized power increases and bihemispheric phase-locking. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Darvas", "given" : "F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Scherer", "given" : "R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sorensen", "given" : "L. B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "930-938", "publisher" : "Elsevier Inc.", "title" : "High gamma mapping using EEG", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1523/JNEUROSCI.3886-06.2007", "ISBN" : "0270-6474", "ISSN" : "0270-6474", "PMID" : "17329441", "abstract" : "In the first large study of its kind, we quantified changes in electrocorticographic signals associated with motor movement across 22 subjects with subdural electrode arrays placed for identification of seizure foci. Patients underwent a 5-7 d monitoring period with array placement, before seizure focus resection, and during this time they participated in the study. An interval-based motor-repetition task produced consistent and quantifiable spectral shifts that were mapped on a Talairach-standardized template cortex. Maps were created independently for a high-frequency band (HFB) (76-100 Hz) and a low-frequency band (LFB) (8-32 Hz) for several different movement modalities in each subject. The power in relevant electrodes consistently decreased in the LFB with movement, whereas the power in the HFB consistently increased. In addition, the HFB changes were more focal than the LFB changes. Sites of power changes corresponded to stereotactic locations in sensorimotor cortex and to the results of individual clinical electrical cortical mapping. Sensorimotor representation was found to be somatotopic, localized in stereotactic space to rolandic cortex, and typically followed the classic homunculus with limited extrarolandic representation.", "author" : [ { "dropping-particle" : "", "family" : "Miller", "given" : "K. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leuthardt", "given" : "E. C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schalk", "given" : "Gerwin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rao", "given" : "R. P. N.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Anderson", "given" : "N. R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moran", "given" : "D. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Miller", "given" : "J. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ojemann", "given" : "J. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Neuroscience", "id" : "ITEM-2", "issue" : "9", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "2424-2432", "title" : "Spectral Changes in Cortical Surface Potentials during Motor Movement", "type" : "article-journal", "volume" : "27" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Darvas et al., 2010; Miller et al., 2007)", "plainTextFormattedCitation" : "(Darvas et al., 2010; Miller et al., 2007)", "previouslyFormattedCitation" : "(Darvas et al., 2010; Miller et al., 2007)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Darvas et al., 2010; Miller et al., 2007).Given the considerable advantages of MRI for providing excellent spatial resolution of brain activity ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1093/cercor/bhu150", "ISBN" : "1460-2199 (Electronic)\\r1047-3211 (Linking)", "ISSN" : "14602199", "PMID" : "24994817", "abstract" : "The precise delineation of auditory areas in vivo remains problematic. Histological analysis of postmortem tissue indicates that the relation of areal borders to macroanatomical landmarks is variable across subjects. Furthermore, functional parcellation schemes based on measures of, for example, frequency preference (tonotopy) remain controversial. Here, we propose a 7 Tesla magnetic resonance imaging method that enables the anatomical delineation of auditory cortical areas in vivo and in individual brains, through the high-resolution visualization (0.6 \u00d7 0.6 \u00d7 0.6 mm(3)) of intracortical anatomical contrast related to myelin. The approach combines the acquisition and analysis of images with multiple MR contrasts (T1, T2*, and proton density). Compared with previous methods, the proposed solution is feasible at high fields and time efficient, which allows collecting myelin-related and functional images within the same measurement session. Our results show that a data-driven analysis of cortical depth-dependent profiles of anatomical contrast allows identifying a most densely myelinated cortical region on the medial Heschl's gyrus. Analyses of functional responses show that this region includes neuronal populations with typical primary functional properties (single tonotopic gradient and narrow frequency tuning), thus indicating that it may correspond to the human homolog of monkey A1.", "author" : [ { "dropping-particle" : "", "family" : "Martino", "given" : "Federico", "non-dropping-particle" : "De", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moerel", "given" : "Michelle", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Xu", "given" : "Junqian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moortele", "given" : "Pierre Francois", "non-dropping-particle" : "Van De", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ugurbil", "given" : "Kamil", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Goebel", "given" : "Rainer", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Yacoub", "given" : "Essa", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Formisano", "given" : "Elia", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Cerebral Cortex", "id" : "ITEM-1", "issue" : "10", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "3394-3405", "title" : "High-resolution mapping of myeloarchitecture in vivo: Localization of auditory areas in the human brain", "type" : "article-journal", "volume" : "25" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/mrm.24156", "ISBN" : "1522-2594 (Electronic) 0740-3194 (Linking)", "PMID" : "22231859", "abstract" : "Echo-planar imaging is the most widely used imaging sequence for functional magnetic resonance imaging (fMRI) due to its fast acquisition. However, it is prone to local distortions, image blurring, and signal voids. As these effects scale with echo train length and field strength, it is essential for high-resolution echo-planar imaging at ultrahigh field to address these problems. Partially parallel acquisition methods can be used to improve the image quality of echo-planar imaging. However, partially parallel acquisition can be affected by aliasing artifacts and noise enhancement. Another way to shorten the echo train length is to reduce the field-of-view (FOV) while maintaining the same spatial resolution. However, to achieve significant acceleration, the resulting FOV becomes very small. Another problem occurs when FOV selection is incomplete such that there is remaining signal aliased from the region outside the reduced FOV. In this article, a novel approach, a combination of reduced FOV imaging with partially parallel acquisition, is presented. This approach can address the problems described above of each individual method, enabling high-quality single-shot echo-planar imaging acquisition, with submillimeter isotropic resolution and good signal-to-noise ratio, for fMRI at ultrahigh field strength. This is demonstrated in fMRI of human brain at 7T with an isotropic resolution of 650 mum.", "author" : [ { "dropping-particle" : "", "family" : "Heidemann", "given" : "R M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ivanov", "given" : "D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Trampel", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fasano", "given" : "F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Meyer", "given" : "H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pfeuffer", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Turner", "given" : "R", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Magn Reson Med", "edition" : "2012/01/11", "id" : "ITEM-2", "issue" : "5", "issued" : { "date-parts" : [ [ "2012" ] ] }, "note" : "Heidemann, Robin M\nIvanov, Dimo\nTrampel, Robert\nFasano, Fabrizio\nMeyer, Heiko\nPfeuffer, Josef\nTurner, Robert\nMagn Reson Med. 2012 Nov;68(5):1506-16. doi: 10.1002/mrm.24156. Epub 2012 Jan 9.", "page" : "1506-1516", "title" : "Isotropic submillimeter fMRI in the human brain at 7 T: combining reduced field-of-view imaging and partially parallel acquisitions", "type" : "article-journal", "volume" : "68" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(De Martino et al., 2015; Heidemann et al., 2012)", "plainTextFormattedCitation" : "(De Martino et al., 2015; Heidemann et al., 2012)", "previouslyFormattedCitation" : "(De Martino et al., 2015; Heidemann et al., 2012)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(De Martino et al., 2015; Heidemann et al., 2012) it is highly desirable to take advantage of this feature in the investigation of the origin of electrophysiological responses, where non-invasive EEG/MEG recordings are limited. However, previous studies ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1093/schbul/sbv092", "ISBN" : "4940741059805", "ISSN" : "17451701", "PMID" : "26163477", "abstract" : "Objectives. Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). Methods. EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG- informed fMRI). Results. A gamma-band\u2013specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. Conclusions. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeat- edly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia.", "author" : [ { "dropping-particle" : "", "family" : "Leicht", "given" : "Gregor", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Vauth", "given" : "Sebastian", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Polomac", "given" : "Nenad", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Andreou", "given" : "Christina", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Rauh", "given" : "Jonas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mu??mann", "given" : "Marius", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karow", "given" : "Anne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mulert", "given" : "Christoph", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Schizophrenia Bulletin", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "239-249", "title" : "EEG-Informed fMRI Reveals a Disturbed Gamma-Band-Specific Network in Subjects at High Risk for Psychosis", "type" : "article-journal", "volume" : "42" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuroimage.2009.10.058", "ISBN" : "1095-9572 (Electronic)\\r1053-8119 (Linking)", "ISSN" : "10538119", "PMID" : "19878729", "abstract" : "Oscillations in the gamma-band frequency range have been described to be more closely connected to hemodynamic changes as assessed with functional magnetic resonance imaging (fMRI) than other aspects of neuronal activity. In addition, gamma-band oscillations have attracted much interest during the last few years since they are thought to play a crucial role in many aspects of brain function related to perception and cognition. It was the aim of the present simultaneous EEG-fMRI study to identify brain regions specifically involved in the generation of the auditory gamma-band response (GBR) using single-trial coupling of EEG and fMRI. Ten healthy subjects participated in this study. Three different runs of an auditory choice reaction task with increasing difficulty were performed. Brain activity was recorded simultaneously with high density EEG (61 channels) and fMRI (1.5 T). BOLD correlates of the GBR have been predicted using the single-trial amplitude of the GBR. Reaction times (p < 0.001), error rates (p < 0.05) and self-ratings of task difficulty and effort demands (p < 0.001) were related to the level of difficulty in the task. In addition, we found a significant influence of task difficulty on the amplitude of the GBR at Cz (p < 0.05). Using single-trial coupling of EEG and fMRI GBR-specific activations were found only in the auditory cortex, the thalamus and the anterior cingulate cortex (ACC) in the most difficult run. Single-trial coupling might be a useful method in order to increase our knowledge about the functional neuroanatomy of \"neural ensembles\" coupled by 40 Hz oscillations. \u00a9 2009 Elsevier Inc. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Mulert", "given" : "C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leicht", "given" : "G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hepp", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirsch", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Karch", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pogarell", "given" : "O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Reiser", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hegerl", "given" : "U.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "J\u00e4ger", "given" : "L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moller", "given" : "H. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "McCarley", "given" : "R. W.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "NeuroImage", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "2238-2247", "title" : "Single-trial coupling of the gamma-band response and the corresponding BOLD signal", "type" : "article-journal", "volume" : "49" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-3", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)", "previouslyFormattedCitation" : "(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Leicht et al., 2016; Mulert et al., 2010; Scheeringa et al., 2011) have required considerable compromise on spatial resolution (slice thickness ranging from 4-8mm with slice gaps of 0.4-1mm) and/or brain coverage (between 35 and 120mm) to provide a sufficient quiet period to TR ratio (ranging between 30-90% of time) and sampling rate of MRI responses (TRs between 3 and 3.63s). With the current implementation of MB we have shown that these trade-offs can be minimised such that 3 mm isotropic voxels, with no slice gap and 99 mm brain coverage with a quiet period to TR ratio of 75%, can be achieved with a TR of 3s.BOLD responses and coupling to EEG responses and future research possibilitiesExploiting the advantages of EEG-MB fMRI has allowed us to show the potential of this technique for non-invasively investigating brain function. We found that, out of all our regressors, the boxcar model of the finger abductions showed the strongest correlation with the BOLD response, with the largest activations arising in the contralateral postcentral gyrus (M1) [-38, -32, 66] mm, and supplementary motor area [-4, -14, 70] mm as well as bilateral S2. All of which are regions expected to be activated in a simple sensorimotor task. Interestingly the regions of gamma-BOLD correlation were smaller and more focal, with peak activity being observed between the postcentral gyrus and superior parietal lobule both in contralateral [-32,-42, 60] mm, ipsilateral [34, -42, 60] mm regions, and a central peak found between precentral and postcentral gyrus at [2, -36, 56] mm. The contralateral activation extends to directly posterior to the hand-knob area of the left sensorimotor cortex, further suggesting this was a localised, task specific response. The bilaterality of this correlation, given the gamma ERS was lateralised to the left cM1, appears surprising, but falls consistently within the bilateral somatosensory cortex and therefore is likely to arise due to the mutual correlation of BOLD signals between the contralateral and ipsilateral regions of the somatosensory network for this task.It is unsurprising given the robust task employed that the BOLD response was well characterised by a simple boxcar model and that this showed the strongest activations in the motor network. However, single-trial variability in BOLD and gamma ERS response amplitudes were well coupled in the somatosensory network. This finding supports previous work showing a tight coupling of natural variability in BOLD and gamma responses in the visual system ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Logothetis", "given" : "Nikos K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "J Neurosci", "id" : "ITEM-1", "issue" : "10", "issued" : { "date-parts" : [ [ "2003" ] ] }, "page" : "3963-3971", "title" : "The underpinnings of the BOLD functional magnetic resonance imaging signal", "type" : "article-journal", "volume" : "23" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.neuron.2010.11.044", "abstract" : "Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies. Trial-by-trial BOLD fluctuations correlated positively with trial-by-trial fluctuations in high-EEG gamma power (60-80 Hz) and negatively with alpha and beta power. Gamma power on the one hand, and alpha and beta power on the other hand, independently contributed to explaining BOLD variance. These results indicate that the BOLD-gamma coupling observed in animals can be extrapolated to humans performing a task and that neuronal dynamics underlying high- and low-frequency synchronization contribute independently to the BOLD signal.", "author" : [ { "dropping-particle" : "", "family" : "Scheeringa", "given" : "Ren\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Petersson", "given" : "Karl-Magnus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Oostenveld", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grothe", "given" : "Iris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Norris", "given" : "David G", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hagoort", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bastiaansen", "given" : "Marcel C M", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Neuron", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "572-583", "title" : "Neuronal Dynamics Underlying High- and Low-Frequency EEG Oscillations Contribute Independently to the Human BOLD Signal", "type" : "article-journal", "volume" : "69" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Logothetis, 2003; Scheeringa et al., 2011)", "plainTextFormattedCitation" : "(Logothetis, 2003; Scheeringa et al., 2011)", "previouslyFormattedCitation" : "(Logothetis, 2003; Scheeringa et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Logothetis, 2003; Scheeringa et al., 2011) and extends these findings into the sensorimotor modality. It is likely that the BOLD-gamma coupling was most evident in the sensory network where the variability to the task was the greatest and therefore least explained by the boxcar constant main effect. We hypothesize that a greater amount of response variability was elicited in the somatosensory network than the motor cortex as the subject’s abduction movements showed such a high level of consistency in both timing and amplitude (Fig 4), reflecting similar motor output. However, it is possible that the sensation of finger movement, and thus the somatosensory input, may have varied depending on what external surfaces were touched with the finger when subjects’ arms were slightly cramped for space inside the scanner. Whilst this cannot be proven with these data, it provides a basis for further investigation. The lack of significant correlation between the beta ERD and BOLD responses appears a surprising result given previous reports of negative beta-BOLD correlations ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.20585", "abstract" : "Similar to the posterior alpha rhythm, pericentral (Rolandic) EEG rhythms in the alpha and beta frequency range are referred to as \"idle rhythms\" indicating a \"resting state\" of the respective system. The precise function of these rhythms is not clear. We used simultaneous EEG-fMRI during a bimanual motor task to localize brain areas involved in Rolandic alpha and beta EEG rhythms. The identification of these rhythms in the MR environment was achieved by a blind source separation algorithm. Rhythm \"strength\", i.e. spectral power determined by wavelet analysis, inversely correlated most strongly with the fMRI-BOLD signal in the postcentral cortex for the Rolandic alpha (mu) rhythm and in the precentral cortex for the Rolandic beta rhythm. FMRI correlates of Rolandic alpha and beta rhythms were distinct from those associated with the posterior \"classical\" alpha rhythm, which correlated inversely with the BOLD signal in the occipital cortex. An inverse correlation with the BOLD signal in the respective sensory area seems to be a general feature of \"idle rhythms\".", "author" : [ { "dropping-particle" : "", "family" : "Ritter", "given" : "Petra", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Villringer", "given" : "Arno", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Hum Brain Mapp", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "1168-1187", "title" : "Rolandic alpha and beta EEG rhythms' strengths are inversely related to fMRI-BOLD signal in primary somatosensory and motor cortex", "type" : "article-journal", "volume" : "30" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Ritter et al., 2009)", "plainTextFormattedCitation" : "(Ritter et al., 2009)", "previouslyFormattedCitation" : "(Ritter et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Ritter et al., 2009) and the clear beta band responses which we observed (Fig 5b). However, here we considered the variability in the EEG response which explained variance in the BOLD data in addition to that explained by a constant amplitude boxcar model. Further inspection of our data with a fixed effects cluster corrected Z>2.0 group analysis showed that beta-BOLD correlations were observed in central and ipsilateral motor cortex, but these did not survive mixed effects Z>2.3. Therefore it seems that the effect size was too weak for the beta correlation to arise in our data sample. Beta ERD is widely observed during preparation and execution of movements ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.conb.2010.02.015", "ISBN" : "1873-6882 (Electronic)\\r0959-4388 (Linking)", "ISSN" : "09594388", "PMID" : "20359884", "abstract" : "In this review, we consider the potential functional role of beta-band oscillations, which at present is not yet well understood. We discuss evidence from recent studies on top-down mechanisms involved in cognitive processing, on the motor system and on the pathophysiology of movement disorders that suggest a unifying hypothesis: beta-band activity seems related to the maintenance of the current sensorimotor or cognitive state. We hypothesize that beta oscillations and/or coupling in the beta-band are expressed more strongly if the maintenance of the status quo is intended or predicted, than if a change is expected. Moreover, we suggest that pathological enhancement of beta-band activity is likely to result in an abnormal persistence of the status quo and a deterioration of flexible behavioural and cognitive control. \u00a9 2010 Elsevier Ltd.", "author" : [ { "dropping-particle" : "", "family" : "Engel", "given" : "Andreas K.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Current Opinion in Neurobiology", "id" : "ITEM-1", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "156-165", "title" : "Beta-band oscillations-signalling the status quo?", "type" : "article", "volume" : "20" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1371/journal.pone.0060060", "ISBN" : "1932-6203 (Electronic)\\r1932-6203 (Linking)", "ISSN" : "19326203", "PMID" : "23555884", "abstract" : "Although beta oscillations (\u2248 13-35 Hz) are often considered as a sensorimotor rhythm, their functional role remains debated. In particular, the modulations of beta power during preparation and execution of complex movements in different contexts were barely investigated. Here, we analysed the beta oscillations recorded with electroencephalography (EEG) in a precued grasping task in which we manipulated two critical parameters: the grip type (precision vs. side grip) and the force (high vs. low force) required to pull an object along a horizontal axis. A cue was presented 3 s before a GO signal and provided full, partial or no information about the two movement parameters. We measured beta power over the centro-parietal areas during movement preparation and execution as well as during object hold. We explored the modulations of power in relation to the amount and type of prior information provided by the cue. We also investigated how beta power was affected by the grip and force parameters. We observed an increase in beta power around the cue onset followed by a decrease during movement preparation and execution. These modulations were followed by a transient power increase during object hold. This pattern of modulations did not differ between the 4 movement types (2 grips \u00d72 forces). However, the amount and type of prior information provided by the cue had a significant effect on the beta power during the preparatory delay. We discuss how these results fit with current hypotheses on the functional role of beta oscillations.", "author" : [ { "dropping-particle" : "", "family" : "Zaepffel", "given" : "Manuel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Trachel", "given" : "Romain", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kilavik", "given" : "Bj\u00f8rg Elisabeth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brochier", "given" : "Thomas", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "PLoS ONE", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1-10", "title" : "Modulations of EEG Beta Power during Planning and Execution of Grasping Movements", "type" : "article-journal", "volume" : "8" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1002/hbm.20585", "abstract" : "Similar to the posterior alpha rhythm, pericentral (Rolandic) EEG rhythms in the alpha and beta frequency range are referred to as \"idle rhythms\" indicating a \"resting state\" of the respective system. The precise function of these rhythms is not clear. We used simultaneous EEG-fMRI during a bimanual motor task to localize brain areas involved in Rolandic alpha and beta EEG rhythms. The identification of these rhythms in the MR environment was achieved by a blind source separation algorithm. Rhythm \"strength\", i.e. spectral power determined by wavelet analysis, inversely correlated most strongly with the fMRI-BOLD signal in the postcentral cortex for the Rolandic alpha (mu) rhythm and in the precentral cortex for the Rolandic beta rhythm. FMRI correlates of Rolandic alpha and beta rhythms were distinct from those associated with the posterior \"classical\" alpha rhythm, which correlated inversely with the BOLD signal in the occipital cortex. An inverse correlation with the BOLD signal in the respective sensory area seems to be a general feature of \"idle rhythms\".", "author" : [ { "dropping-particle" : "", "family" : "Ritter", "given" : "Petra", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Moosmann", "given" : "Matthias", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Villringer", "given" : "Arno", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Hum Brain Mapp", "id" : "ITEM-3", "issue" : "4", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "1168-1187", "title" : "Rolandic alpha and beta EEG rhythms' strengths are inversely related to fMRI-BOLD signal in primary somatosensory and motor cortex", "type" : "article-journal", "volume" : "30" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Engel and Fries, 2010; Ritter et al., 2009; Zaepffel et al., 2013)", "plainTextFormattedCitation" : "(Engel and Fries, 2010; Ritter et al., 2009; Zaepffel et al., 2013)", "previouslyFormattedCitation" : "(Engel and Fries, 2010; Ritter et al., 2009; Zaepffel et al., 2013)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Engel and Fries, 2010; Ritter et al., 2009; Zaepffel et al., 2013), however there is a sparsity of evidence directly linking parameters of the beta ERD amplitude to the quality of motor performance, leaving much still to be understood concerning beta oscillations precise functional role ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/j.cub.2009.07.074", "ISBN" : "1879-0445 (Electronic)\\n0960-9822 (Linking)", "ISSN" : "09609822", "PMID" : "19800236", "abstract" : "Neurons have a striking tendency to engage in oscillatory activities. One important type of oscillatory activity prevalent in the motor system occurs in the beta frequency band, at about 20 Hz. It is manifest during the maintenance of tonic contractions and is suppressed prior to and during voluntary movement [1-7]. This and other correlative evidence suggests that beta activity might promote tonic contraction, while impairing motor processing related to new movements [3, 8, 9]. Hence, bursts of beta activity in the cortex are associated with a strengthening of the motor effects of sensory feedback during tonic contraction and with reductions in the velocity of voluntary movements [9-11]. Moreover, beta activity is increased when movement has to be resisted or voluntarily suppressed [7, 12, 13]. Here we use imperceptible transcranial alternating-current stimulation to entrain cortical activity at 20 Hz in healthy subjects and show that this slows voluntary movement. The present findings are the first direct evidence of causality between any physiological oscillatory brain activity and concurrent motor behavior in the healthy human and help explain how the exaggerated beta activity found in Parkinson's disease can lead to motor slowing in this illness [14]. \u00a9 2009 Elsevier Ltd. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Pogosyan", "given" : "Alek", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Gaynor", "given" : "Louise Doyle", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Eusebio", "given" : "Alexandre", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brown", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Current Biology", "id" : "ITEM-1", "issue" : "19", "issued" : { "date-parts" : [ [ "2009" ] ] }, "page" : "1637-1641", "title" : "Boosting Cortical Activity at Beta-Band Frequencies Slows Movement in Humans", "type" : "article-journal", "volume" : "19" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.conb.2010.02.015", "ISBN" : "1873-6882 (Electronic)\\r0959-4388 (Linking)", "ISSN" : "09594388", "PMID" : "20359884", "abstract" : "In this review, we consider the potential functional role of beta-band oscillations, which at present is not yet well understood. We discuss evidence from recent studies on top-down mechanisms involved in cognitive processing, on the motor system and on the pathophysiology of movement disorders that suggest a unifying hypothesis: beta-band activity seems related to the maintenance of the current sensorimotor or cognitive state. We hypothesize that beta oscillations and/or coupling in the beta-band are expressed more strongly if the maintenance of the status quo is intended or predicted, than if a change is expected. Moreover, we suggest that pathological enhancement of beta-band activity is likely to result in an abnormal persistence of the status quo and a deterioration of flexible behavioural and cognitive control. \u00a9 2010 Elsevier Ltd.", "author" : [ { "dropping-particle" : "", "family" : "Engel", "given" : "Andreas K.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Fries", "given" : "Pascal", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Current Opinion in Neurobiology", "id" : "ITEM-2", "issue" : "2", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "156-165", "title" : "Beta-band oscillations-signalling the status quo?", "type" : "article", "volume" : "20" }, "uris" : [ "" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.expneurol.2012.09.014", "ISBN" : "0014-4886", "ISSN" : "00144886", "PMID" : "23022918", "abstract" : "Since the first descriptions of sensorimotor rhythms by Berger (1929) and by Jasper and Penfield (1949), the potential role of beta oscillations (~ 13-30 Hz) in the brain has been intensely investigated. We start this review by showing that experimental studies in humans and monkeys have reached a consensus on the facts that sensorimotor beta power is low during movement, transiently increases after movement end (the \"beta rebound\") and tonically increases during object grasping. Recently, a new surge of studies exploiting more complex sensorimotor tasks including multiple events, such as instructed delay tasks, reveal novel characteristics of beta oscillatory activity. We therefore proceed by critically reviewing also this literature to understand whether modulations of beta oscillations in task epochs other than those during and after movement are consistent across studies, and whether they can be reconciled with a role for beta oscillations in sensorimotor transmission. We indeed find that there are additional processes that also strongly affect sensorimotor beta oscillations, such as visual cue anticipation and processing, fitting with the view that beta oscillations reflect heightened sensorimotor transmission beyond somatosensation. However, there are differences among studies, which may be interpreted more readily if we assume multiple processes, whose effects on the overall measured beta power overlap in time. We conclude that beta oscillations observed in sensorimotor cortex may serve large-scale communication between sensorimotor and other areas and the periphery. \u00a9 2012 Elsevier Inc.", "author" : [ { "dropping-particle" : "", "family" : "Kilavik", "given" : "Bj\u00f8rg Elisabeth", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Zaepffel", "given" : "Manuel", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brovelli", "given" : "Andrea", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "MacKay", "given" : "William A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Riehle", "given" : "Alexa", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Experimental Neurology", "id" : "ITEM-3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "15-26", "title" : "The ups and downs of beta oscillations in sensorimotor cortex", "type" : "article", "volume" : "245" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Engel and Fries, 2010; Kilavik et al., 2013; Pogosyan et al., 2009)", "plainTextFormattedCitation" : "(Engel and Fries, 2010; Kilavik et al., 2013; Pogosyan et al., 2009)", "previouslyFormattedCitation" : "(Engel and Fries, 2010; Kilavik et al., 2013; Pogosyan et al., 2009)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Engel and Fries, 2010; Kilavik et al., 2013; Pogosyan et al., 2009). Given the beta ERD has been considered to be a simple gating mechanism ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1002/hbm.23189", "ISBN" : "1097-0193 (Electronic)\\r1065-9471 (Linking)", "ISSN" : "10970193", "PMID" : "27061243", "abstract" : "\u00a9 2016 Wiley Periodicals, Inc. Movement induced modulation of the beta rhythm is one of the most robust neural oscillatory phenomena in the brain. In the preparation and execution phases of movement, a loss in beta amplitude is observed [movement related beta decrease (MRBD)]. This is followed by a rebound above baseline on movement cessation [post movement beta rebound (PMBR)]. These effects have been measured widely, and recent work suggests that they may have significant importance. Specifically, they have potential to form the basis of biomarkers for disease, and have been used in neuroscience applications ranging from brain computer interfaces to markers of neural plasticity. However, despite the robust nature of both MRBD and PMBR, the phenomena themselves are poorly understood. In this study, we characterise MRBD and PMBR during a carefully controlled isometric wrist flexion paradigm, isolating two fundamental movement parameters; force output, and the rate of force development (RFD). Our results show that neither altered force output nor RFD has a significant effect on MRBD. In contrast, PMBR was altered by both parameters. Higher force output results in greater PMBR amplitude, and greater RFD results in a PMBR which is higher in amplitude and shorter in duration. These findings demonstrate that careful control of movement parameters can systematically change PMBR. Further, for temporally protracted movements, the PMBR can be over 7 s in duration. This means accurate control of movement and judicious selection of paradigm parameters are critical in future clinical and basic neuroscientific studies of sensorimotor beta oscillations.", "author" : [ { "dropping-particle" : "", "family" : "Fry", "given" : "Adam", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mullinger", "given" : "Karen J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "O'Neill", "given" : "George C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barratt", "given" : "Eleanor L.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "Peter G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Bauer", "given" : "Markus", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Folland", "given" : "Jonathan P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brookes", "given" : "Matthew J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Human Brain Mapping", "id" : "ITEM-1", "issue" : "7", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "2493-2511", "title" : "Modulation of post-movement beta rebound by contraction force and rate of force development", "type" : "article-journal", "volume" : "37" }, "uris" : [ "" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1002/hbm.21016", "ISBN" : "1097-0193 (Electronic)\\r1065-9471 (Linking)", "ISSN" : "10659471", "PMID" : "21229612", "abstract" : "The neural basis of the blood oxygenation level-dependent (BOLD) response measured using fMRI is poorly understood. This work involves a parallel study using fMRI and MEG to explore the relationship between the neuromagnetic and the BOLD responses in motor cortex. Linearity of the BOLD response was investigated using a simple graded motor task, manipulating stimulus duration. Significant changes in the BOLD response, and \u03b2-band synchrony were localised to the contra-lateral primary motor cortex, with the appearance of ipsilateral activation on lowering the statistical threshold. This suggests a strong correlation between the two responses. The BOLD time-courses were compared with virtual sensor traces at the peak of \u03b2-band activity. Linearity of the event-related desynchronisation (ERD) in the \u03b2-band response during movement and the corresponding post-movement \u03b2-rebound were investigated. The BOLD responses were found to increase monotonically and non-linearly with stimulus duration, whereas the \u03b2-band ERD produced a roughly linear increase. The non-linearity in BOLD is probably largely haemodynamic in origin, but it could also reflect other neural phenomena, including the \u03b2-rebound. \u00a9 2007.", "author" : [ { "dropping-particle" : "", "family" : "Stevenson", "given" : "Claire M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Brookes", "given" : "Matthew J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "Peter G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Human Brain Mapping", "id" : "ITEM-2", "issue" : "2", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "182-197", "title" : "\u03b2-Band correlates of the fMRI BOLD response", "type" : "article-journal", "volume" : "32" }, "uris" : [ "" ] } ], "mendeley" : { "formattedCitation" : "(Fry et al., 2016; Stevenson et al., 2011)", "plainTextFormattedCitation" : "(Fry et al., 2016; Stevenson et al., 2011)", "previouslyFormattedCitation" : "(Fry et al., 2016; Stevenson et al., 2011)" }, "properties" : { "noteIndex" : 0 }, "schema" : "" }(Fry et al., 2016; Stevenson et al., 2011) required to allow neuronal activity involved in task execution to take place in other, typically higher, frequency bands it is conceivable that the amplitude variability of the ERD is less related to the task performance and reflects more of a binarised signal to permit the necessary activation. In conclusion we show that EEG can be safely acquired concurrently with GE-EPI MB-fMRI data and allows the investigation of neuronal and hemodynamic task responses with high spatial, temporal and spectral resolution. We use a simple motor task in this work to show that tight gamma-BOLD coupling is observed on an individual trial basis, agreeing with previous invasive recordings in both animal and human visual/auditory cortex. In the future such methodologies that allow detailed integration of a wide frequency range of neural signals may be used to build a more complete understanding of pathways of feedforward and feedback neural communication and of how such signals contribute to neurovascular coupling mechanisms and the generation of the hemodynamic response. AcknowledgementsWe thank the Birmingham Nottingham Strategic Collaboration Fund for supporting this work and MU and a University of Nottingham Anne McLaren Fellowship for funding KJM and a University of Birmingham Fellowship for funding SDM. ReferencesADDIN Mendeley Bibliography CSL_BIBLIOGRAPHY Auerbach, E.J., Xu, J., Yacoub, E., Moeller, S., Ugurbil, K., 2013. Multiband accelerated spin-echo echo planar imaging with reduced peak RF power using time-shifted RF pulses. Magn Reson Med 69, 1261–1267. doi:10.1002/mrm.24719Bagshaw, A.P., Aghakhani, Y., Bénar, C.G., Kobayashi, E., Hawco, C., Dubeau, F., Pike, G.B., Gotman, J., 2004. EEG-fMRI of focal epileptic spikes: Analysis with multiple haemodynamic functions and comparison with gadolinium-enhanced MR angiograms. Hum. Brain Mapp. 22, 179–192. doi:10.1002/hbm.20024Ball, T., Demandt, E., Mutschler, I., Neitzel, E., Mehring, C., Vogt, K., Aertsen, A., Schulze-Bonhage, A., 2008. 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Temperature was calculated relative to an initial 5-minute baseline recording made before the scan started.Figure 3. Spatial maps of tSNR of middle slice of the stack for each subject for sparse image acquisition sequences with MB factor 2 (top row) and 3 (bottom row). The values below the each map show the mean tSNR ± SD over all grey matter voxels for a given subject and scan.Figure 4. EMG activity recorded from the right FDI during the passive (-9 to -7.5s) and active (0-1.5s) time windows (here the time windows are concatenated together for visualisation purposes) from three representative subjects. The average timecourse across all trials and runs from a representative subject is shown. Onset of the first auditory cue occurred at 0s relative to index finger abduction movements. Error bars denote standard deviation across runs.Figure 5. Group average (N=10) T-statistic beamformer maps showing regions exhibiting power increases and decreases in a) gamma- and b) beta-power, respectively, during the active window (0-1.5s) as compared with the passive window (-9.5-7s). The crosshairs represent the group average of the individual VE locations found in cM1 for the gamma (a) and beta (b) frequency activity. Figure 6. Group mean (N=10) time-frequency spectrograms demonstrating changes in the EEG signal power in cM1 relative to the passive window (-9 to -7.5s) for a&b) gamma ERS and c&d) beta ERD VE location. The passive window was located in an MR quiet period and before any anticipation of the stimulus. Time is displayed relative to the auditory cue onset. Spectrograms were calculated with frequency resolution of 2.5Hz with spectral smoothing of ±10Hz. a&c) show 18s whole-trial duration, note the residual GAs during fMRI acquisition periods. b&d) show the gamma and beta power responses during the active window (0 to 1.5s) where movement occurred, with the passive window data appended pre-stimulus for comparison. Colour bars denote the relative change in power from the average power during the passive window period (baseline measure) of the passive window for each frequency. See Figure S4 for absolute power changes of same time-frequency spectrograms.Figure 7. Group average (N=10) fMRI mixed effects results. Positive correlation of BOLD signal to the boxcar model of right index finger abduction movements (red-yellow) and areas of positive gamma-BOLD correlation (green). All correlations are cluster corrected with p < 0.05, masked with motor cortex. The crosshairs represent the peak positive gamma-BOLD correlation in cM1 (at [-32, -42, 60] mm). ................
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