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Anatomy and Physiology of the Auditory Nervous System

      The cochlear nucleus receives all known acoustic input to the brain by way of the auditory nerve and in turn, initiates all ascending auditory pathway. In this nucleus, the electrophysiological responses of most neurons exhibit significant changes in the representation of acoustic information compared to that of the auditory nerve. In order to understand how sound is processed at this initial stage of the central nervous system, our task necessarily involves studying identified cell populations, analyzing their synaptic connections, and revealing features of their signaling capabilities. Each neuron population in the cochlear nucleus is hypothesized to receive a distinctive pattern of excitatory and inhibitory inputs and to express characteristic subsets of receptors, G proteins, and second messengers.

     Together, these features form the substrate for stimulus coding in each cell population. We combine intracellular recording and staining methods, track tracing techniques, and immunocytochemistry in the auditory nerve and cochlear nucleus in our investigations of cellular circuits and neuronal signaling in the mature animal. We are also studying how deafness affects the synaptic development of this system in mutant mice and congenitally deaf cats. In this way, we can explore both the macro and molecular contributions to acoustic processing at this level of the auditory nervous system.