Gabriel Kreiman Gabriel.Kreiman@childrens.harvard

[Pages:10]Human neurophysiology

Gabriel Kreiman Gabriel.Kreiman@childrens.harvard.edu

Children's Hospital Boston, Harvard Medical School McGovern Institute for Brain Research Massachusetts Institute of Technology

? Genomics, microarrays, transcriptional regulation ? Visual object recognition ? More info at

Single neuron recordings in epileptic patients

MRI

Electrodes

?Patients with pharmacologically intractable epilepsy

?Electrodes implanted to localize seizure focus

Fried et al. J.Neurosurgery 1999

Spike sorting

?Targets include the hippocampus, entorhinal cortex, amygdala and parahippocampal gyrus

Collaboration with neurosurgeonKIrtezimhaakn,FKroiecdh,(FUriCedLA(2)0a0n0)dNCahturriestNoef uKroscchie(nCcael3te:9c4h6)-953

Inferior temporal cortex

projects to frontal cortex and the medial temporal lobe (among other

places)

Saleem & Tanaka. J.Neurosci.1996 Suzuki. Sem.Neurosci. 1996 Miller. Nat.Rev.Neurosci. 2000 Logothetis & Sheinberg. Ann.Rev.Neurosci. 1996

Individual neurons in the human MTL show visual selectivity and visual invariance

Emotional face (100) Object (51)

Spatial (105)

Animal (46)

Car (17)

Face drawing (134) Famous face (100) Pattern (54)

1000 ms

R Entorhinal Cortex

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Two extreme forms of representation

Fully distributed representation

Every unit responds to every object Every object is represented by the

combined ensemble activity

Completely sparse representation (grandmother representation)

Every unit responds to only 1 object Every object is represented by 1 neuron

A neuron selective to 3 different views of Bill Clinton

n=9

n=14

n=13

n=7

n=5

n=7

n=6

n=6

n=7

n=4

n=11

n=11

n=10

n=7

n=4

1000 ms

R amygdala

A neuron selective to 7 different views of actress Jennifer Aniston

ROC area=1

L Parahippocampal gyrus

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