Functional disconnection between the prefrontal and parietal cortices during working memory processing in schizophrenia: a [[sup.15]O][H.sub.2]O PET study

Objective: The prefrontal-parietal circuits have been reported to play an important role in working memory. The purpose of this study was to use direct neuroimaging to address whether interregional correlation in the prefrontal-parietal circuits is impaired in schizophrenia. Method: [[sup.15]O][H.sub.2]O positron emission tomography was used to compare regional blood flow changes in 12 schizophrenic and 12 healthy comparison subjects during the n-back sequential-picture working memory task. Interregional correlation was assessed by correlating the regional activation of the lateral prefrontal area with that of other activated areas in each subject group. Results: Dorsolateral prefrontal activation was observed around the right superior frontal sulcus in the healthy subjects, and ventrolateral prefrontal activation below the right inferior frontal sulcus was observed in the schizophrenic patients. Activation in the right lateral prefrontal cortex was significantly correlated with activation in the bilateral inferior parietal region in the healthy subjects but was not correlated with any regional activation in the patients. Conclusions: The findings suggest prefrontal-parietal functional disconnection, particularly prefrontal dissociation and abnormal prefrontal-parietal interaction, during working memory processing in schizophrenia.