The long-term goal of this laboratory is to understand the neural circuitry of the first relay in the central taste pathways - the rostral nucleus tractus solitarius (rNTS) - that receives afferent sensory input via the facial (VII) and glossopharyngeal (IX) nerves. The experiments described in this proposal build upon the progress achieved during the last grant period investigating the basic neurobiology of the rNTS. We will use whole cell recording techniques in both an in vitro brain slice preparation and acutely dissociated rNTS neurons to study: 1. The biophysical characteristics of afferent input to the rNTS by investigating morphological, pharmacological and synaptic properties of neurons receiving input from the VIIth and IXth nerves exclusively, as well as rNTS neurons with convergent afferent input from the VIIth and IXth nerves. 2. The mechanisms of inhibition in rNTS by investigating the morphological, biophysical, pharmacological and immunocytochemical properties of rNTS interneurons. 3. The biophysical properties of the rNTS protection neurons that connect to the pons as well as to brainstem motor nuclei. These experiments will define the biophysical and synaptic properties of principal and intrinsic neurons of rNTS permitting us to refine and further develop a neural circuit diagram of the rNTS. Since the sense of taste has a primary role in feeding, in regulating food and fluid intake, and in the initiation of oral reflex activity such as tongue movements and salivary secretion, it is important to learn how sensory information originating in taste receptors is processed by taste relays in the central nervous system. The experiments outlined in this proposal will provide important new information on the neural circuits responsible for integrating, modifying and distributing sensory information originating in taste receptors, and thereby provide greater understanding of the role of the gustatory system in feeding and feeding-related disorders.