Dysfunctional activation of the default mode network in response inhibition in schizophrenia

The aim of this study was to characterize dysfunctional cerebral activation in patients with schizophrenia while they performed a response inhibition task. To achieve this, performance on the task and functional magnetic resonance imaging (fMRI) were compared between healthy control subjects (HC) and patients with schizophrenia (SZ). We focused on the default mode network (DMN), as there is strong evidence in the literature that lack of DMN suppression in schizophrenia is associated with cognitive impairment including poor response inhibition. fMRI was used to measure blood-oxygen-level-dependent activation in 84 subjects (44 SZ and 40 HC) while they performed a Go NoGo task. The subjects were also evaluated for psychiatric symptoms and immediate visual memory. SZ performed more poorly than HC on the task; they had a higher number of commission errors. On the fMRI, the patients consistently evidenced higher activation than the controls in several areas of the default mode network (DMN) including the precuneus, rostral anterior cingulate, parahippocampus and insula. The higher brain activation in the patients with schizophrenia indicates a failure to deactivate the DMN while they perform the response inhibition task. These findings point to the importance of DMN dysfunction as an underlying cause of impairment in response inhibition in schizophrenia. DMN disruptions play an essential role in the cognitive impairment present in schizophrenia.