Project Summary/Abstract To understand mental health and disease, we need to understand the function of the brain at the level of genes, gene regulatory networks, neurons, circuit structure, and physiology. Drosophila has emerged as one of the most powerful model systems for these questions, given the range of tools and the tractability of analyzing complex behaviors at all these levels. This proposal seeks to understand Drosophila reproductive behaviors. One reason Drosophila is such a powerful system is that the sex- specific master regulatory transcription factors that direct reproductive behaviors are known. This has provided a powerful molecular inroad into identifying and manipulating the neurons that underlie these behaviors. These tools can also be used to perform neuron-specific mutational studies to discover the functions of genes that direct behaviors, which leverages one of the biggest strengths of the Drosophila model system. In addition, this system affords an unparalleled model to both examine the sex-specific development of these neurons and how they are modified by adult experiences. Research using the Drosophila model has continued to uncover biologically important processes that have informed on human health and disease, including studies of the nervous system and behavior. The work will build off of my laboratories 15-year NIGMS funded research program. We will continue to address these behavioral questions using cutting-edge molecular-genetic, genomic, proteomic, behavioral and microscopy tools to gain insights into complex behaviors.