The research in this proposal investigates the potential influence of forebrain projections to brainstem nuclei involved in ingestive behaviors. Specifically, the parabrachial nucleus (PBN) in the dorsal pons traffics both gustatory and visceral sensory information and is essential to the acquisition of learned taste aversions and expression of salt appetite. In normal animals, these procedures alter the response of gustatory neurons in the nucleus of the solitary tract and PBN. Extracellular recordings from gustatory neurons in the PBN in response to 0.3 M sucrose, 0.1 M NaCl, 0.03 M citric acid and 0.0003 M quinine HCl will be assessed. Then, stimulation of the central nucleus of the amygdala (CNA) will be done through a bipolar electrode before, during, and after sapid stimulation with each chemical. These procedures will be performed in both acutely prepared, lightly, anesthetized rats and chronically prepared, awake, behaving rats. This condition is necessary due to differences between PBN taste cells in anesthetized and awake preparations. Given the strong reciprocal connection between the CNA and the PBN, it is not surprising that the amygdala is a structure of import to the display of more complex taste- guided behaviors. Lesions in this forebrain area disrupt learned taste aversions and the expression of a salt appetite. The objective of the current proposal is to determine how activity in the CNA modulates the response profiles of gustatory neurons in the PBN. If our prediction is born out, then the data from these experiments will provide insight to potential mechanisms related to centrifugal control of gustatory sensory processing. Any effects that occur with these procedures will inform investigations of both the forebrain and brainstem.
