The candidate is an Assistant Professor of Psychiatry, Board Certified in General and Child Psychiatry. He is proposing a career development plan designed to acquire the necessary expertise to conduct neurodevelopmentally-informed studies of childhood Obsessive Compulsive Disorder (OCD) utilizing a systems-neuroscience approach. To achieve this aim, the candidate will acquire general clinical research skills, and focused training in neurobehavioral and neuroimaging methodologies. In recent years, there has been an increased recognition of OCD as a severe, high prevalent and chronically disabling disorder. Despite the fact that OCD is three times more common than schizophrenia and half as common as depression, there has been surprisingly little systematic investigation of the disorder. Because OCD emerges during childhood or adolescence in 33% to 50% of cases, studies of the illness during childhood near the point of illness onset are of particular importance in order to study the psychobiology of the disorder before the course of illness confounds and treatment effects confound data, and to determine whether neurodevelopmental abnormalities contribute to the etiology of the disorder. To date, however, there has been no systematic study in young- onset, medication-naive OCD patients close to the point of illness onset. Neurobiological models for OCD have consistently implicated orbital prefrontal cortical (OrbPFC) and basal ganglia circuits in the pathophysiology of this disorder, but they typically have not utilized a developmental framework for conceptualizing or studying the illness. The applicant has conducted studies demonstrating disturbances of response suppression in OCD, a neuropsychological function believed to be subserved largely by OrbPFC. A developmental neurobiologic approach to examine brain circuits involved in neuropsychiatric disorders of childhood such as OCD is critical to the understanding of how developmental brain changes can lead to psychiatric illness, and to the modification of its presentation with age. During the SDAC award period, the candidate proposes to develop expertise in: 1) clinical research methods related to diagnostic assessment, 2) the neurobehavioral and neuroimaging assessment of fronto-striatal circuitry implicated in the pathophysiology of OCD, and 3) developmentally informed strategies for studying the interplay of psychological and brain development. This training program will prepare him to undertake neurodevelopmentally informed studies of OCD designed to investigate the role of anatomic and neurophysiologic disturbances in fronto-striatal circuitry in childhood OCD.