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S74. HYPERACTIVATION OF LEFT MEDIAL FRONTAL AND CINGULATE GYRUS MEDIATES SOUND-INDUCED FLASH ILLUSION IN NON-AFFECTIVE PSYCHOSIS

Methods: Forty-nine individuals with SocAhn and 33 well-matched controls underwent a fMRI session, during which they were instructed to envision positive or neutral future events in next year in response to the cue words. Each trial was divided into construction phase and elaboration phase. After scanning, participants received an interview to confirm they were able to project themselves into future and rated their experience in future events. Results: Three contrasts were identified to examine the main effect of emotion [Positive Neutral] and phase [Construction Elaboration], and their interaction [(Positive_Construction – Neutral_Construction) – (Positive_Elaboration – Neutral_Elaboration)]. One sample t test was conducted on these contrasts in each group and the results demonstrated that, in the control group, a set of regions including the bilateral caudate, bilateral amygdala, the left medial prefrontal (mPFC), and the left inferior parietal lobe were more engaged in envisioning positive future episodes relative to neutral episodes. However, preferential engagement of these regions was not observed in the SocAhn group. Both the SocAhn and control groups exhibited similar brain activation for the phase contrast. In addition, no significant clusters were shown for the interaction contrast in both groups, which may reflect no significant emotion difference in construction and elaboration of future events in these participants. Two sample t test results indicated that compared to controls, individuals with SocAhn exhibited hypo-activation in the right caudate and the right precuneus cortex when envisioning positive future events (relative to neutral events). Subsequent ROI analysis indicated that social interaction in positive future events was correlated with the engagement of bilateral amygdala (left, r = 0.46, p = 0.001; right, r = 0.43, p = 0.003) in the SocAhn group. In the control group, social interaction was correlated with activation of the left mPFC (r = 0.43, p = 0.02). Discussion: The present findings suggest there is reduced engagement of the caudate and the precuneus cortex in individuals with SocAhn when they envision positive future events. In addition, social interaction involved in positive future episodes is related to activation in different regions in individuals with SocAhn and controls.