We are conducting brain imaging studies to explore a neural basis for risky behaviors in disinhibited individuals. Component 3 will use samples identified in Component 2, to study the differential brain activation during risky decision making associated with individual differences in behavioral disinhibition. This component utilizes a novel assessment of decisions to engage in risk taking and response to the reward and loss consequences of such decisions developed for use in functional magnetic resonance imaging. In collaboration with Component 2's twin studies, the heritability of performance on this novel task and its relationship to behavioral disinhibition and HIV risk behaviors will be determined.