The sense of taste involves chemosensory stimuli that usually are complex mixtures rather than single pure substances. It remains critical to know whether the taste system treats stimulus mixtures differently from their individually presented components. This work uses the relatively simple taste system of the catfish, which is exquisitely sensitive to amino acid stimuli, to understand how such neural information about mixtures is processed. Electrophysiology on single nerve cells in the peripheral taste system will be used to see what types of mixture interactions (suppression or enhancement) are present, whether different nerves process a mixture differently, and whether the mixture interactions are predictable based on responses to the individual components of the mixture. Responses of nerve cells in the brain will reveal how the inputs from different peripheral fiber types converge, and whether mixture information is processed differently between periphery and brain. Specific behaviors elicited by particular amino acids, such as feeding, will be used to determine how well discrimination can be done by taste alone, and how mixtures affect behavior. This study using this unique model system will have an impact on neuroscience in general, by increasing our understanding of how complex sensory information in general is processed, by providing useful comparisons with other model chemosensory systems in insects and crustaceans, and by providing useful analogies to current work in visual and auditory analysis of complex signals. It also is likely to have an impact on biotechnology, by providing useful information on how mixtures affect flavor, and by offering the potential for chemosensory modulation of feeding behavior in aquaculture.
