MPOA · Neural mechanism underlying the central regulation of male sexual arousal and ejaculation

Sexual behavior patterns are unique among the behavioral repertoire of animals. Sex serves no survival advantage for the individual per se, but is vital for species preservation. To this end, evolution has hedonically biased animals to engage in behaviors that culminate in the conspecific transfer of genetic material. Male sexual behavior is characterized by distinct phases in this behavioral action sequence leading up to ejaculation. Lesions of the medial preoptic area (MPOA), an anterior extension of the hypothalamus, in rodents have been shown to eliminate both reward-seeking, or appetitive (female pursuit and anogenital investigation), and reward-consuming, or consummatory (mounting, intromissions, and ejaculation), male sexual behaviors. Furthermore, focal lesion studies and physiological evidence suggests the presence of separate populations within the MPOA mediating the control of these two phases, and behavioral evidence points to the idea that the performance of appetitive and consummatory behaviors are reciprocally related. However, the mechanistic role of the MPOA in controlling downstream circuitry facilitating male sexual arousal, copulation, and the interaction of these dimensions of behavior has not been explored. This proposal aims to understand how male sexual arousal and copulatory performance are encoded in the brain, utilizing activity-dependent genetic labeling approaches, in vivo calcium imaging, causal optogenetic manipulation of neuronal subpopulations, and genetic-based tracing methods. The project will be the first to mechanistically address how the brain provides descending control over male arousal and ejaculation, exposing potential central mechanisms that could be acted on for the treatment of sexual dysfunction.