Hormones have strong effects on behavior. The sex hormones estrogen and testosterone, for example, are responsible for major differences in the behaviors of men and women. The Kristan laboratory studies how hormones initiate and control behavior. To get a precise understanding of these mechanisms, they work with an animal, the medicinal leech, which produces a variety of complex behaviors with a relatively simple nervous system. Studying the control of swimming, crawling, and feeding, they have elucidated how leeches produce behaviors and choose among them. Understanding gained from these studies has informed experiments on more complex animals, including humans, which employ the same mechanisms to decide among possible behavioral responses. The Kristan group will use the same electrophysiological, pharmacological, and behavioral techniques that have proven so successful for them in understanding behavioral choice to study the cellular basis for behavioral modulation by hormones. They will determine how an analog of vasopressin causes courtship, copulation, and egg deposition in medicinal leeches. Vasopressin is a peptide hormone that is broadly distributed across the animal kingdom. All animals, from snails to humans, use vasopressin to induce and modify reproductive and parenting behaviors. Treating leeches with a homologue of vasopression reliably elicits leech reproductive behavior. The Kristan group will characterize activity in the nervous system before and during conopressin treatment. Their studies will show how this hormone causes individually identified neurons to change their activity and induces the animal to produce the constellation of behaviors that are essential for successful reproduction and, thereby, the continuation of the species. This project, from its beginning, has been conducted primarily by undergraduates, and a major component of the project will continue to give these students an opportunity to take part in cutting-edge research.
