Striatal functional activation and psychosis risk
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The striatum is involved in learning from feedback. Psychosis is strongly related to increased striatal dopamine. The goal of the current research is to examine whether psychosis risk is associated with neural evidence consistent with increased striatal dopamine. If psychosis risk is associated with increased striatal dopamine, then it is expected that psychosis risk would be associated with decreased striatal activation on a task involving learning from both positive and negative feedback, a probabilistic category learning task (PCLT; i.e. the Weather Prediction Task). Further, it is also expected that psychosis risk would be associated with increased striatal activation for unexpected reward but decreased striatal activation for unexpected punishment on a task that allows for separate assessment of reward and punishment feedback, a reversal learning task (RLT). In the current study, there were two groups of college student participants: (a) psychosis risk (n = 21) who had both extreme levels of self-reported psychotic-like beliefs and experiences as well as at least moderate levels of interview-rated current attenuated psychotic symptoms (APS); and (b) controls (n = 20) who had average levels of self-reported psychotic-like beliefs and experiences. Participants completed both the PCLT and RLT during fMRI scanning. As expected there was decreased striatal activation on the PCLT in psychosis risk. Further, as expected, on the RLT, for unexpected reward psychosis risk was associated with increased striatal activation, but for unexpected punishment psychosis risk was associated with decreased striatal activation. The current results suggest that psychosis risk is associated with a pattern of neural dysfunction that is consistent with increased striatal dopamine in psychosis risk.
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