Impaired intrinsic motivation in psychosis risk relates to ventral striatum activation to self-generated reinforcement signals

BACKGROUND: Youth at risk for psychosis based on subthreshold positive symptoms (PS) show elevated negative symptoms such as amotivation, associated with disability and increased risk of psychotic transition. Intrinsic motivation (IM), the desire to obtain internal satisfactions such as mastery or curiosity, is more impaired in psychosis than extrinsic motivation (EM), the desire to obtain external rewards. However, the neural mechanisms underlying IM impairment in PS have scarcely been studied, and never with measures designed for this purpose. METHODS: We applied a novel fMRI fractal memory task that leveraged distinct feedback conditions designed to engage IM and EM processes, along with self-reported IM and EM, in adolescents and young adults with PS (n = 95) and healthy controls (CT, n = 31). RESULTS: We hypothesized that IM would generate reinforcement signals in the ventral striatum (VS), a core motivation region, as individuals internally evaluated their performance relative to their expectations. We further hypothesized that reduced VS activation would relate dimensionally to lower self-reported IM across both PS and CT groups. Consistent with these hypotheses, VS and related motivation circuitry preferentially activated to higher confidence task choices and to reward prediction error during performance feedback. VS activation during task choices related selectively to IM but not EM. CONCLUSIONS: Our findings highlight the role of VS in encoding self-generated reinforcement signals, and demonstrate a selective relationship between VS activation and IM. Understanding the link between VS dysfunction and impaired IM will facilitate therapeutic advances to remediate IM deficits in those at risk for psychosis.