DESCRIPTION (provided by applicant): Appropriate social behavior often demands self-control. Both neuropsychiatric disorders (e.g., schizophrenia, addiction) as well as disease states (e.g., HIV positivity, brain lesions) can lead to changes in the neural mechanisms involved in self-control - often with effects most strongly manifested in social contexts. Understanding how the brain identifies social contexts, evaluates potential outcomes, and guides selection of appropriate behavior would provide insight into these disorders and the development of new treatments. Recent work - including from our group - demonstrates that neural activity in temporo-parietal junction (TPJ) signals information relevant for identifying social context, that these social signals influence valuation processes in orbitofrontal cortex (OFC) and ventral striatum (VS), and that social value signals inform reward comparison processes in ventromedial prefrontal cortex (vmPFC). Yet, this now-standard model for social decision making leaves unanswered key questions about brain function and dysfunction, especially how social contexts can potentiate maladaptive decision making observed in disorders. We propose and empirically test a novel two-stage neural circuit model of social decisions. The first stage involves identification of a social context, which we hypothesize relies on computations in TPJ that shape subsequent valuation and decision processes elsewhere. In a second stage, control processes shape ongoing behavior toward social goals (e.g., maximizing the acquisition of information about others, shaping interpersonal reputations), which we refer to as social control. We propose to evaluate this model using an integrated set of experiments conducted in humans and monkeys. We will use similar tasks that manipulate the nature and quality of social contexts (e.g., cooperative or competitive) for decision making, involve both social and non-social reward outcomes, and provide complementary information from functional magnetic resonance imaging (fMRI) in humans, neurophysiological recordings in monkeys, and repetitive transcranial magnetic stimulation (rTMS) in both species (including simultaneous neural recordings in monkeys).