Olfactory information comes into the brain from the level of the olfactory receptor neurons to the first processing center of the forebrain, the olfactory bulb. However, functional information as to how odors are processed at more central neural levels is fragmentary at best. A key question is how information about biologically relevant odors is handled by the cerebral lobes, after arriving via the olfactory tracts from the olfactory bulbs. The channel catfish, Ictalurus punctatus, a teleost fish, is the only vertebrate species for which there is a clear correlation across the morphological type of olfactory receptor neuron, the specific molecular transduction system, the type of biologically relevant odor detected, and the local portion of the olfactory bulb used to process this information. This project uses electrophysiological recording by multi-electrode methods as well as single electrodes, to determine whether biologically relevant odors of amino acids, bile salts, and nucleotides are represented in by local activity showing an 'odotopic' map in the cerebral lobes as they are in the olfactory bulb; to determine the response properties of odor-responsive neurons within the cerebral lobes; and to determine whether the odor-induced synchrony of activity seen in olfactory receptor neurons modulates odor responses within the cerebral lobes. Results will provide a new level of understanding higher-level processing of olfactory information in vertebrates, and will provide an evolutionary and comparative perspective on how odors are processed in cortical neurons. The issue of synchronous oscillating activity is relevant to computational and theoretical models of brain function. Because teleost fish comprise the largest number of vertebrate species, and are economically important worldwide, this work has importance beyond neuroscience to comparative physiology and ecology, and to aquaculture. Finally, this project promotes the teaching and training of postdoctoral, graduate and undergraduate students, including those from under-served groups, in an EPSCoR-designated state.
