Integration of taste and olfactory signals in gustatory cortex

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DESCRIPTION (provided by applicant): Integration of sensory information from multiple modalities is believed to enhance the detection of convergent stimuli. This multimodal integration was originally theorized to occur only in higher order cortical areas, such as prefrontal cortex. However, recent research has shown multimodal sensory responses in every primary sensory cortex, including gustatory cortex (GC). GC is the primary cortex responsible for processing information related to taste and is known to code multisensory information related to taste, such as temperature, touch and anticipatory cues. However, the most conspicuous sensory interaction, that of taste and olfaction, has not been explored at the GC circuit-level. Taste and olfaction are intimately linked. Anatomical and neuroimaging studies have begun to describe the synergistic integration of these two modalities and suggest GC as a primary integrative chemosensory node. Despite this great progress, very little information is available on whether and how single neurons in GC integrate multimodal chemosensory integration. The proposed research is a three step approach, all of which rely upon multielectrode techniques to record ensembles of single neurons in GC while rats intraorally sample tastes and odors. The first experiment is designed to determine how taste and odor are represented by single neurons in GC. After a better understanding of GC chemosensory response, the second experiment will test the hypothesis that odor-taste experience modulates chemosensory activity in GC. The third experiment continues along this trajectory to explore how incongruent odor-taste mixtures suppress chemosensory activity in GC. Altogether, the experiments outlined in this R03 proposal will lay a foundation for an in depth understanding of the circuit-level integration of multimodal chemosensory information in GC of alert rodents. If successful, this research will elucidate how single neurons in GC process ecologically synergistic chemosensory information and will establish GC as a primary area of multisensory integration of stimuli related to food.