It has been well established that gonadal steroids regulate reproductive behavior in primates. The main steroid involved in this regulation is testosterone which acts at specific sites in the brain. Although it is known that testosterone stimulates male behavior by acting on the brain, very little is known about the neurobiology of the interaction between the endocrine system and the central nervous system. The goal of Pomerantz's research program is to elucidate this relationship in primates. This research will use state-of-the-art neuroendocrine techniques to study the role of specific areas of the brain that regulate reproductive behavior. The data generated by this research will provide a solid foundation for future research aimed at understanding hormone-mediated neuroendocrine and neurochemical processes that modulate the reproductive behavior of male primates.