Dissertation Research: Physiological mechanisms regulating plasticity in the peripheral auditory system: implications for communication

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Bird song has intrigued and delighted humans for hundreds of years. It is well understood how and why birds sing, how and why males and females differ in the types of sounds that they make, and how and why song production increases in the spring/summer and decreases in the fall/winter. However, whether bird hearing is the same or different between sexes and whether that hearing changes seasonally is poorly understood. In this work the electrical responses of the auditory nerve and brainstem of male and female songbirds will be recorded during the spring and the fall to understand whether the auditory system changes between seasons and whether this change is different between the sexes. Fall birds will be implanted with hormones (estrogen or testosterone) to mimic a spring-like condition. Their responses will be recorded before and after hormone implantation to determine if hormones can change the response of the auditory system to sound. Finally, the inner ear of the bird will be stained to determine whether there are receptors for hormones present in the ear, which could drive seasonal changes. It is expected that females will be more sensitive to sounds than males and that all birds will be more sensitive to sounds in the spring to improve communication during critical times. It is also expected that there will be estrogen and testosterone receptors in the ear which could mediate sex and seasonal effects on auditory processing. Songbirds may be an important model for the study of human hearing because women show hormone-induced changes in hearing that men do not show. Songbirds can help us understand the physiological basis for why humans show these patterns, and this should in turn prove useful in studying the basis of a number of hearing-related diseases. This work will train a promising young graduate student to become an independent scientist. Additonally this study will add to the scientific training of multiple undergraduates who will participate in the research.