| Understanding the principles by which the cellular and molecular substrates of the nervous system are organized and operate to give rise to behavior represents the fundamental goal of neuroscience. The significance of innate behavioral programs for animal life and thus as foci for neuroethological studies has long been apparent. The very innate nature of these rituals suggests that their underlying neural substrates are genetically determined and programmed during development. Thus, neurogenetic approaches to the analysis of such networks facilitate the identification of genes that regulate the development and function of the nervous system to create the potential for complex behaviors. Once identified, these genes themselves may be used as entry points for the dissection of the circuitry they specify to determine the function and contribution of distinct neural populations for specific behavioral processes.; Sexual differentiation represents one of the most profound and significant developmental programs in animals, affecting both the morphological and physiological aspects of growth, development, and function. Most interestingly, given appropriate selective pressure, pathways for sexual development often produce striking sexually dimorphic behaviors. In Drosophila melanogaster, male sexual behavior is regulated by the fruitless branch of the Drosophila sex-differentiation hierarchy. Male-specific Fruitless isoforms (FruM) are expressed throughout the nervous system, including peripheral and central regions previously implicated in sexual behaviors.; We have used a number of molecular genetic techniques to identify the neurons in which FruM is expressed and manipulate populations of these cells in order to determine their function in sexual behavior. These have included targeted inhibition of fruM expression using RNAi, and the introduction of the yeast GAL4 transcription factor into the fru locus via homologous recombination. These strategies have allowed the specific visualization and manipulation of distinct populations of fruM neurons to determine their contributions to male sexual behavior.; Using these approaches, we have begun to characterize the architecture of the circuitry underlying sexual behaviors in Drosophila. At a more general level, these studies begin to address how programs for complex behaviors may be built into the nervous system and demonstrate how neurogenetic approaches may be applied to identification and dissection of their underlying circuitry. |
