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.
This proposal aims to understand how neurons in the gustatory cortex (GC) integrate the chemosensory modalities of taste and smell. In rodents, GC has been traditionally studied for its involvement in taste. Recent data suggests that neurons in GC are multimodal, processing taste-related information such as temperature, touch and anticipatory cues. While the role of GC in processing taste information is well established, very little is known about its involvement in integrating olfactory information. With this proposal, we intend to study how neurons in GC integrate and encode naturally related chemosensory information, taste and odor. Multielectrode recordings in behaving rats will unveil how GC neurons represent tastes and retronasal odors, how experience of an odor- taste association alters that representation, and finally how odor-taste association learning modulates chemosensory activity. The results of these efforts will lay the foundation for an in depth understanding of ecologically related multimodal chemosensory processing at the circuit level in GC. If successful, this research will expand our knowledge of chemosensory processing, point to GC as a primary integrative area of information related to consummatory behaviors and reveal an area to study the interactions between chemosensory processing and behavioral food choice in animal models of eating disorders.
| Bamji-Stocke, Sanaya; Biggs, Bradley T; Samuelsen, Chad L (2018) Experience-dependent c-Fos expression in the primary chemosensory cortices of the rat. Brain Res 1701:189-195 |
| Samuelsen, Chad L; Fontanini, Alfredo (2017) Processing of Intraoral Olfactory and Gustatory Signals in the Gustatory Cortex of Awake Rats. J Neurosci 37:244-257 |
