Behavioral Neuroendocrinology and Neuroethology

     We are interested in the interrelation of hormones, brain, and behavior. We study a variety of avian species that exhibit high degrees of neuroplasticity in response to hormone treatment. These studies are designed to investigate both how hormones act in the brain to affect the learning and activation of behavior and how behavioral and other stimuli are processed by the brain to influence reproductive endocrine activity and the timing of seasonal reproduction. A particular focus is the song control system, a circuit that represents a neural specialization that has evolved in songbirds in association with their ability to produce, learn and perceive complex vocalizations. Several brain nuclei in this circuit express receptors for a variety of hormones including sex steroid hormones and melatonin. Both over the course of development and seasonally in adulthood, hormones are able to induce substantial changes in the total volume specific nuclei and changes in biochemical activity. Also there are substantial sex differences in the size and connectivity of several of these vocal control nuclei in many songbird species.

     Current research activities include: (1) investigations of seasonal brain changes and neural sex differences mediating bird song learning and production; (2) studies addressing how the neuroendocrine system integrates cues that regulate seasonal reproduction including photoperiod and supplementary factors that augment the photo-induction of gonadal growth, such as the perception of conspecific vocalizations; (3) studies of the regulation of the steroid metabolizing enzyme, aromatase,  and the relatively fast actions of 17b-estradiol in relation to the activation of male reproduction behavior in quail.