A fundamental issue of taste physiology is whether there are specific types of responses in specific nerve fibers, or whether there is a continuum of sensitivities across the population of fibers. This project exploits the remarkable taste system of the catfish, which has taste buds all over the skin of the body, to investigate the physiology of taste responses to particular compounds and to particular mixtures. Electrophysiological recording will be used to determine how amino acid taste "quality" and quantity (intensity) are represented in neurons of the facial nerve, which innervates the taste buds. Since in real life taste receptors rarely encounter sequentially spaced delivery of single chemicals, stimuli will include single compounds and mixtures, to see whether, as in invertebrates, responses to taste mixtures are not simply predictable from responses to the individual components. Recordings also will be made in the cells of central pathways that process the taste information through the brainstem and higher gustatory nuclei. This unusual preparation has provided a wealth of fundamental information on taste sensitivity already, and this project will provide results that are likely to have high impact on gustatory research. This physiology also will complement current exciting work on taste biochemistry, and the analyses of complex stimuli are likely to be important to sensory science in general.
