Catherine A. McCormick IBN-9604466 Lay Summary This project investigates the organization of the central nervous system auditory circuits in various species in order to determine if primitive features of the auditory system are present in land vertebrates. The nervous system circuits underlying hearing are known to have a superficial similarity in all vertebrates. The classes of vertebrates differ, however, in the specific portions of the inner ear that are responsive to sound and, at least in part, in the specific cell populations of the brain that participate in auditory processing. The experiments in this project utilize modern neuroanatomical methods to map the auditory circuits in various species and to determine how other brain areas interface with them. The specific connections of the primitive vertebrate auditory receptors, the saccule and lagena, are being compared with the connections of the more recently developed auditory receptor, the basilar papilla. The results will broaden the understanding of the neural systems responsible for hearing as well as provide insights into primitive characteristics of the auditory circuits in early vertebrates. These results will contribute to the understanding of the changes that occurred as the auditory circuits evolved n land vertebrates and may reveal that primitive circuits persist along with more recent ones. Should such primitive circuits exist, they may subsequently be found to have a unique role in the hearing of land vertebrates, including humans. Such information could inform new approaches to understanding hearing deficits. This project is being performed at an institution oriented toward undergraduate education. Undergraduates participate in these studies, leering all of the surgical, laboratory, and analytical skills involved. The active involvement of undergraduates in original research enhances their science training and encourages them to pursue postgraduate training in science or science education at precollege as well as colleg e levels.
