Steroid hormones exert powerful effects on a wide range of mechanisms ranging from development and reproduction to cognition and the establishment of social hierarchies. The new studies proposed here will identify the cellular and molecular events that mediate rapid steroid actions on nerve cells (neurons) that directly generate behavior, in this case vocalizations that are essential for social communication. Long-term influences of steroids on the development and maintenance of vocal behaviors and neurons is well known, but their short-term actions is both unexpected and essentially unexplored. The vocal control system of teleost fish presents the most basic example of how the central nervous system of vertebrates produces social, context-dependent vocalizations. The PI has discovered that androgens, estrogen and cortisol (the major "stress" steroid in teleost fish) induce rapid changes in the output of vocal neurons that parallel the time course of steroid effects on natural calling behaviors. This now provides a model to study the physiological basis for rapid steroid effects on neurons that directly lead to changes in a social behavior. Neurophysiological, molecular and behavioral methods will be used to show how steroids shape neuronal function, where the receptors that mediate these effects are located, and how vocal behaviors are influenced by one or more steroids. The principles identified apply to other vertebrates because vocal, neural and endocrine mechanisms are evolutionarily conserved between teleosts and other groups, including birds and mammals. This research has, and will continue to, train undergraduate, graduate, and postdoctoral students of both sexes from diverse cultural backgrounds and geographic regions and make the results of the research easily accessible to the general public through publications, press interviews and presentations at professional societies, universities, marine biology laboratories and local community science centers.
Project Summary: Understanding how hormones influence the nervous system helps reveal how the brain controls behaviors like vocalization (sound production). Our investigations of the simpler nervous system of fishes have shown that hormones dramatically influence the activity levels of individual neurons and neuron-to-neuron interactions underlying vocal behavior. By adopting an interdisciplinary program of research, we have made significant progress in identifying fundamental mechanisms by which hormones act on the central nervous system to modify behavior. Thus, by combining cellular, molecular and behavioral approaches we have shown that (1) vocal behavior is controlled by a vocal pattern generator in the central nervous system whose rhythmic output directly determines the attributes of natural vocalizations, (2) naturally occurring daily variation in vocal behavior is determined by daily changes in the activity of vocal pattern generating neurons, and (3) naturally occurring steroid hormones, and neurochemicals that rapidly alter patterns of neural activity, can induce changes in vocal neuron activity which mimic daily changes in vocal behavior. Intellectual Merit: The principles identified through this research apply to all vertebrate groups because vocal, neurobiological and hormonal mechanisms are shared between fishes and other vertebrates, including mammals. Broader Impact: This research has made significant contributions to the training of undergraduate, graduate, and postdoctoral students from diverse cultural backgrounds and geographic regions and made the results of the research easily accessible to the general public through publications, press interviews and presentations at professional societies, universities, marine biology laboratories and local community science centers.
