Dissertation Research: Neurophysiological Control of Avian Vocal Behavior

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ABSTRACT Deviche & Gulledge IBN 96-23171 Neurophysiological Control of Avian Vocal Behavior In songbirds, singing is a learned behavior controlled by specific brain regions collectively called the vocal control system. Because the vocal control regions regulate a single behavior, studies on this subject offer a unique opportunity for elucidating the neural bases of behavior. Steroidal hormones play essential roles in this system s sexual differentiation and in vocal behavior learning and expression. However, extensive research on steroid effects has not satisfactorily explained characteristics of the vocal control system at all stages of song development and expression. The investigators have observed opioids and their receptors in vocal control regions. In other systems opioids modulate neuron morphology and survival, sensory processing, and learning and memory. In order to ascertain whether opioids regulate any of these features of vocal control, it is necessary to determine if any correlation exists between vocal control system opioid activity an d particular aspects of singing behavior. The proposed work will use radioimmunoassays to measure opioid concentrations in vocal control regions microdissected from dark-eyed junco (Junco hyemalis) brains during four stages: song template storage, song expression, song recognition, and post- breeding cessation of singing behavior. Additionally, a parallel study that will directly asses the effects of chronic opioid antagonist administration on singing behavior in adult male juncos will be conducted. This project will help direct future research on the role(s) of opioids in controlling behavior.