A dissertation presented to the Watson School of Biological Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Biological Sciences at Cold Spring Harbor Laboratory (July 2007).
In this dissertation, I combined two complementary approaches to study how the brain processes acoustic signals and to characterize neuronal dynamics in the auditory cortex.
As a top-down theoretical analysis of neural behaviors at the population level, we exploited the idea of sparse overcomplete linear representations and developed a model for monaural blind source separation (Asari et al., 2006, 2007). We also derived experimentally testable predictions about the dynamic nature of representations in the auditory cortex.
As a bottom-up experimental analysis at the single-cell level, we used whole-cell recordings in vivo and found that stimulus context could exert surprisingly long-lasting effects in rat auditory cortex, sometimes as long as four seconds (Asari and Zador, submitted). We also found that restricting knowledge of the stimulus history to only a few hundred milliseconds (as in conventional models) reduced the predictable component of the response by about half of that of the optimal infinite-history model.