Deficit in a neural correlate of reality monitoring in schizophrenia patients

Abstract

Patients who suffer from the devastating psychiatric illness schizophrenia are plagued by hallucinations, bizarre behavior, and delusional ideas, such as believing that they are controlled by malevolent outside forces. A fundamental human cognitive operation that may contribute to these hallmark symptoms is the ability to maintain accurate and coherent self-referential processing over time, such as occurs during reality monitoring (distinguishing self-generated from externally perceived information). However, the neural bases for a disturbance in this operation in schizophrenia have not been fully explored. Using functional magnetic resonance imaging, we asked clinically stable schizophrenia patients to remember whether or not they had generated a target word during an earlier sentence completion task. We found that, during accurate performance of this self-referential source memory task, the schizophrenia subjects manifest a deficit in rostral medial prefrontal cortex (mPFC) activity - a brain region critically implicated in both the instantiation and the retrieval of self-referential information in healthy subjects. Impairment in rostral mPFC function likely plays a key role in the profound subjective disturbances that characterize schizophrenia and that are the aspect of the disorder most troubling to patients and to society at large.