Functional brain networks underlying evidence integration and delusional ideation.

Cognitive biases affecting evidence integration contribute to delusions and delusional ideation in the psychosis continuum. In previously published work we observed hyperactivity in a visual attention network (VsAN) during confirmatory evidence integration, and hypoactivity in a cognitive evaluation network (CEN) during disconfirmatory evidence integration in schizophrenia patients with delusions, suggesting that a task-specific imbalance of these networks may contribute to delusion maintenance. In the current study, we investigated whether patterns of aberrant functional connectivity observed in past work were associated with delusional ideation in 41 healthy individuals by examining associations between cognitive biases, subclinical schizotypal traits, and functional brain activity during evidence integration. Behaviourally, we replicated positive associations between schizotypal traits and cognitive biases and further showed that this association was driven by delusional ideation specifically. Constrained principal component analysis for fMRI (fMRI-CPCA) revealed recruitment of the brain networks observed in our previous clinical and non-clinical evidence integration studies: default-mode network (DMN); cognitive evaluation network (CEN); and visual attention (VsAN) network. Moreover, as with clinically-significant delusions, delusional ideation was associated with decreased CEN activity during the processing of disconfirmatory evidence and increased VsAN activity during the processing of confirmatory evidence. These findings suggest that this altered pattern of activation across networks during evidence integration may underlie delusional ideation and delusions in the psychosis continuum.