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

数百年来，鸟类的歌声一直吸引着人们，让人们感到愉悦。鸟类鸣叫的方式和原因，雄性和雌性在鸣叫类型上的差异，以及鸣叫在春夏增加而在秋冬减少的方式和原因，都是很容易理解的。然而，鸟类的听觉在性别之间是相同的还是不同的，以及这种听觉是否会随季节变化，人们知之甚少。在这项工作中，将记录雄性和雌性鸣禽在春季和秋季的听觉神经和脑干的电反应，以了解听觉系统是否在季节之间发生变化，以及这种变化是否在性别之间有所不同。秋天的鸟儿将被植入激素（雌激素或睾丸激素），以模仿春天的状态。他们的反应将在激素植入前后被记录下来，以确定激素是否能改变听觉系统对声音的反应。最后，将对鸟的内耳进行染色，以确定耳朵中是否存在激素受体，这可能会导致季节变化。预计雌性会比雄性对声音更敏感，所有的鸟类在春天都会对声音更敏感，以便在关键时刻加强沟通。我们还预计，耳朵中可能存在雌性激素和雄性激素受体，它们可以调节性别和季节对听觉加工的影响。鸣禽可能是研究人类听力的一个重要模型，因为女性表现出激素引起的听力变化，而男性则没有。鸣禽可以帮助我们理解为什么人类表现出这些模式的生理基础，而这反过来又会在研究一些听力相关疾病的基础上被证明是有用的。这项工作将把一个有前途的年轻研究生培养成一个独立的科学家。此外，本研究还将对参与研究的多名本科生进行科学训练。

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.