Temporal Coding and Palatability in Gustatory Cortex

Brandeis University, Waltham MA

Investigators

Linked publications & trials

Abstract

[unreadable] DESCRIPTION (provided by applicant): When a taste is on an animal's tongue, behavior must soon follow--the substance must either be swallowed or expelled. This intimate coupling between stimulus and response implies that the function of gustatory neural circuits is to transform taste activity into response activity in 2-3 seconds; this in turn implies that neurons in these circuits may respond to tastes with temporal codes (i. e., responses that change through time) that reflect the perception-to-action transformation. My lab has begun to look for such content in taste- related temporal codes in cortex, identifying epochs of the neural responses in which "pure" chemosensory information seems to become imbued with emotional meaning in anticipation of consumption or rejection. The experiments proposed here will use large arrays of tastes, in association with chronic recordings of ensembles of GC single neurons, careful observation of rat taste-related behaviors, and pharmacological manipulation, to thoroughly explore features of the temporal codes that are related to taste identity, palatability/emotion, and the act of consuming or rejecting taste substances. First, we will look at responses to multiple tastes from each 'basic taste' category (sweet, salty, sour, and bitter), to determine how more and less similar tastes are distinguished by their associated temporal codes. Next, we will examine neural responses to, and preferences for, a range of taste concentrations-concentrations that should all be recognizable as the same taste, but that should vary widely in palatability and even in exact flavor; this should allow us to independently manipulate the palatability-related parts of the temporal codes. We will also manipulate the palatability of an individual tastant by increasing the rats' appetite for sodium, to test whether such changes are represented only in palatability-related parts of the temporal codes. Finally, we will inactivate the amygdala, thought to be the source of much of the palatability/emotional information in the brain, during tasting; if the amygdala truly imbues the taste with palatability, then this manipulation should only effect the palatability-related parts of cortical temporal codes. These experiments should greatly expand our understanding of how taste processing works in cortex, and as such should affect how we think about sensory processing in general. [unreadable] [unreadable] [unreadable]