Event
Bioengineering Seminar Series: Didier A. Depireux
Wednesday, November 19, 2008
2:00 p.m.
PEPCO Room, Kim Engineering Building
Professor William Bentley
(310) 405-4321
bentley@umd.edu
Please note the special day, time and location.
Untangling the Coding of Complex Sounds in Auditory Cortex
Presented by Didier A. Depireux
Assistant Professor, Anatomy and Neurobiology
University of Maryland Baltimore
Auditory cortex has solved the challenging task of extracting and separating overlapping sound streams with a complex time-frequency representation. The corresponding complex neural response has been partially described by a linear measure, called the spectro-temporal receptive field. To better understand the full nature of the time-frequency analysis performed in cortex, we have further characterized the responses of auditory neurons in cortex and midbrain to complex sounds. We have shown, in the awake animal, the existence of non-trivial nonlinearities (not solely the result of the positivity of spike counts or saturating nonlinearities), such as contrast tuning, and dynamics in the tuning of neural filtering, whereby the filtering characteristics of a neuron depends on recent spectro-temporal content over a tens of millisecond timescale. The complexity of the cortical responses arises in part because of a feedback system within the auditory pathway between cortex and midbrain, a system still very poorly understood, but which is increasingly attracting attention.
About the Speaker
Didier Depireux received his M.Sc. and Ph.D. in Theoretical Physics with Dr. S.J. Gates from the University of Maryland at College Park. After post-doctoral work in integrable systems in Canada, he became interested in computational neuroscience and the sense of hearing, and joined the laboratory of Dr. S.A. Shamma at the Institute for Systems Reseach, College Park. In 2002, he joined the faculty of the University of Maryland School of Medicine in Baltimore. Currently he is assistant professor at the department of Anatomy and Neurobiology. Research in his laboratory is focused, first, on the encoding of sounds such as speech and music in the auditory pathway, and second on the neural changes associated with the induction of tinnitus (ear ringing), and the corresponding effects by which amide anesthetics provide temporary relief from tinnitus.
