Disturbed functional connectivity within brain networks subserving domain-specific subcomponents of working memory in schizophrenia: relation to performance and clinical symptoms.

INTRODUCTION: Disturbed interregional functional connectivity has been hypothesized to be a promising marker of schizophrenia. The relationship between working memory (WM) impairment, disturbed functional connectivity, and the characteristic symptoms of schizophrenia, however, remains elusive.

METHODS: We used functional MRI (fMRI) to investigate in patients with schizophrenia and matched controls the patterns of functional connectivity during the performance of different tasks selectively engaging subcomponent processes of working memory.

RESULTS: Compared with controls, patients showed reduced connectivity of the prefrontal cortex with the intraparietal cortex and the hippocampus and abnormal negative interactions between the ventrolateral and dorsolateral prefrontal cortex during the non-articulatory maintenance of phonological information. During the maintenance of visuospatial information, patients presented reduced connectivity between regions in the superior parietal and occipital cortex, as well as enhanced positive connectivity of the frontal eye field with visual processing areas.

DISCUSSION: Our findings suggest complex dysregulations within the networks supporting working memory functions in schizophrenia, which manifest as decreased positive and abnormal negative interactions. Correlations between the connection strength and WM performance suggest that these dysregulations may be neurofunctional correlates of the WM deficits seen in schizophrenia. Altered prefronto-hippocampal and parieto-occipital connectivity was further found to be associated with higher positive symptoms, providing a possible explanation for the development of delusions and disorganization symptoms.

CONCLUSION: The present findings can help to better understand the relationship between altered patterns of synchronized brain activity and the cognitive and clinical symptoms of schizophrenia.