All organisms must choose between investing resources in producing young or maintaining self through feeding, growth, and repair of tissues. Each time an organism makes this choice, it must also cope with the associated trade-offs that directly impact both its survival and reproductive fitness. Despite the critical importance of choosing between self-maintenance and reproduction, the mechanisms that shape these decision-making processes is not yet understood. In addition, it is not clear how resource availability, such as the quantity of body fat stores and the presence of mates and food, influences the motivation to pursue one opportunity over another. The goal of this project is to understand if and how glucocorticoid hormones interact with specific neuropeptides in the brain to regulate the behavioral switch between reproduction and feeding. This project provides outstanding opportunities for student involvement, with hands-on training in techniques that integrate neuroendocrine methods with behavioral analyses in the field. All project participants receive training in effective science communication techniques using a teaching module that includes participation in a community-based workshop on the "Neurobiology of Decision-Making." The proximate goal is to broaden the participation of diverse students in science education and community outreach. The researcher also incorporates project results into inquiry-based learning modules for use in the classroom, thereby exposing many more students to scientific discovery than is typically achievable in the laboratory.
This project merges field and laboratory studies to better understand the neuroendocrine basis of decision-making. Because the decision to pursue reproductive versus foraging opportunities occurs on a short time scale (minutes to hours) in many animals, it is often difficult to disentangle the mechanisms that regulate both the individual behaviors and the transition between them. In this context, organisms that exhibit seasonal transitions between temporally distinct life-history stages can illuminate the mechanisms that regulate the underlying behaviors in all animals. Red-sided garter snakes (Thamnophis sirtalis) are a phenomenal vertebrate model in this regard because reproduction and foraging are relegated to temporally distinct life-history stages, and snakes undergo dramatic changes in hormone-brain-behavior relationships during the transition to foraging. Based on extensive preliminary data from the investigator's laboratory, this project tests a model in which glucocorticoids interact with the neuromodulators arginine vasotocin and neuropeptide Y to facilitate life-history transitions. The investigator uses a combination of pharmacological manipulation, immunohistochemistry, Western blot, and behavioral assays to achieve the following aims: (1) Determine the function of elevated glucocorticoids during life-history transitions; (2) Determine how glucocorticoids interact with neuromodulators to induce life-history transitions; and (3) Determine if and how neuromodulators are associated with altered sensitivity of the hypothalamus-pituitary-adrenal axis. Results from this project will provide a framework for understanding the neuroendocrine basis of decision-making and the mechanisms by which neuroendocrine signals reconfigure regulatory systems.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
