Columbia University



How can destabilized birdsong inform us about language impairment in aphasia?

Leonard L. LaPointe, PhD

Frank Johnson, PhD

John A. Thompson, MS

Florida State University

Malcolm R. McNeil, PhD

Sheila Pratt, PhD

University of Pittsburgh

Species-specific vocal production represents one of many strategies by which organisms communicate. Only a few (oscine passerines and humans) develop their vocal behavior through experience against the backdrop of time-sensitive sensory and motor experiences. One unique vocal learning exemplar is the zebra finch (Taeniopygia guttata). The process of vocal learning in zebra finches occurs during two overlapping phases: auditory learning (post hatch days 20-35) and sensory-motor integration (post hatch days 35-80). During auditory learning, the juvenile bird attends to and memorizes a tutor vocal pattern, followed by a sensory-integration phase where the bird practices singing and gradually modifies output. The birdsong laboratory in the Program in Neuroscience at Florida State University has a research agenda that includes systematic ablation of discrete, interconnected telencephalic nuclei underlying vocal learning and production of the zebra finch (Thompson, et al, 2007). Of particular interest to us is the trajectory of disruption and subsequent recovery of song patterns (3-5 days). The nature of paradigmatic (syllables, or units of meaning) and syntagmatic (order) changes that characterize post-surgical destabilization and recovery of zebra finch song and how these might compare to human language dissolution and recovery are in need of examination for their potential to inform processes in human speech.

Acoustic wave files and spectrographic records have been analyzed for patterns of vocal destabilization and recovery in a sample of 6 adult zebra finches in our laboratory (See Figure 1 for an exemplar) We present pre-and post-operative differences along several acoustic parameters:

• Changes in structure and number of paradigmatic (notes or syllables) vs. syntagmatic (order) in destabilized birdsong and in recovery of crystallized birdsong

• Changes in birdsong motif and extraneous syllables before, during and after recovery

• Differences in the relative syllable duration and inter-syllabic interval duration across pre-and post-operative conditions

• Changes in the acoustic parameters of pitch, frequency modulation, pitch goodness, and entropy across pre-operative and recovery phases

Human and non-human communication has been investigated from a variety of perspectives within science. Birdsong learning is a worthy model system for the study of acquisition with many parallels to human language development (Kuhl, 2003). Whether or not these commonalities extend to patterns of dissolution and recovery is a research agenda that has interested very few neural ethologists, neurolinguists, or aphasiologists. Cross disciplinary and cross-species exploration of the parameters of dissolution and recovery of zebra finch birdsong against the backdrop of aphasia is a unique perspective that may encourage discovery or refinement of distinctive models of language loss and recovery.

References

Kuhl, P. (2003). Human speech and birdsong: Communication and the social brain. Proceedings of the National Academy of Sciences, 100, 17, 9645–9646.

Thompson, J.A., Wu, W., Bertram, R., & Johnson, F. (2007). Auditory-Dependent Vocal Recovery in Adult Male Zebra Finches Is Facilitated by Lesion of a Forebrain Pathway That Includes the Basal Ganglia. Journal of Neuroscience, 27(45):12308-12320.

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