Dr. Zipursky and his colleagues are studying the role of the gene neurexin IV in brain development. The gene is the fruit fly Drosophila melanogaster's homolog of the human autism-linked gene CNTNAP2, and it is believed to play a role in regulating the formation of connections between neurons in the brain. Zipursky's team plans to explore the gene's role in the fruit fly's visual system. Using the many tools available to manipulate genes in this well-studied model, the researchers will investigate the role of neurexin IV in various classes of neurons, such as those that sense light and those that relay visual information to the brain. The researchers will also analyze the functions of the handful of genes that have been shown to interact with neurexin IV. Together, these studies will provide a detailed picture of how neurexin IV regulates wiring in various types of neurons, and will set the stage for developing genetic screens to identify other components of the neurexin IV pathways. Zipursky and colleagues hope to use the Drosophila model to shed light on how neurexin IV — and by extension, the human CNTNAP2 — functions during development, and to identify neurexin-interacting genes whose human counterparts could also contribute to autism.