Dysfunctional neural networks associated with impaired social interactions in early psychosis: an ICA analysis.

The "default mode", or baseline of brain function is a topic of great interest in schizophrenia research. Recent neuroimaging studies report that the symptoms of chronic schizophrenia subjects are associated with temporal frequency alterations as well as with the disruption of local spatial patterns in the default mode network (DMN). Previous studies both on chronic and medicated subjects with psychosis suffered from limitations; on this basis, it was hypothesized that the default mode network showed abnormal activation and connectivity in young and neuroleptic-naïve patients with first-episode psychosis. This study investigated emotional responses to pleasant and unpleasant/disgusting visual stimuli by a resting-state analysis of fMRI-data from 12 untreated first-episode psychosis patients with prevalently negative symptomatology versus 12 healthy subjects. We chose this experimental task to explore the functional link between default mode network and hedonic processing which has been proposed as a marker of cerebral dysfunction in psychotic disorder and implicated in its pathophysiology. Independent Component Analysis (ICA) was used to identify the default mode component. Both healthy and first-episode subjects showed significant spatial differences in the default mode network. In first-episode subjects, medial frontal hypoactivity and cerebellar hyperactivity were correlated with the severity of negative symptoms.