LONG TERM RECORDING FROM AFFERENT TASTE FIBERS

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Development of an implantable, multielectrode array has made it possible to record chronically, over periods of several weeks, from sensory fibers of taste nerves that innervate the tongue. In the current proposal, the electrode array will be used to systematically test hypotheses about neural discharge properties of peripheral taste fibers over long time frames that encompass numerous cycles of taste bud cell turnover, and synapse remodeling. In addition, the multielectrode recording device will be progressively refined to improve and expand its range of capabilities. The rat chorda tympani nerve will be dissected and implanted with the multielectrode array through which taste nerve fibers regenerate. Subsequently, recordings will be made from the same single fiber, or sets of fibers, for weeks. In Specific Aim 1, chronic recordings from single taste fibers of the chorda tympani nerve will be used to test the hypotheses that response characteristics of taste fibers, and receptive field properties, remain stable during cycles of taste bud cell turnover and synapse remodeling. In Specific Aim 2, simultaneous recordings from several individual fibers will be studied over weeks to test the hypothesis that there is a unique pattern of fiber activity for separate chemical qualities, and that the pattern remains stable over time. In Specific Aim 3, an implantable telemetry system will be used with the multielectrode array to record from chorda tympani fibers in awake rats and investigate the pattern of neural activity during feeding and drinking. The implantable, multielectrode recording array and its further refinement make possible tests of hypotheses about basic taste neurobiology that could not be resolved with previous neurophysiological techniques. Also, studies of taste fiber responses in behaving animals become feasible with the implantable device. Furthermore, continued refinement of, and experiments with, the implantable electrode array can lead to potential applications as a neural prosthesis in regeneration and restoration of sensory and motor function after trauma or disease.