The neural basis of disturbed efference copy mechanism in patients with schizophrenia

Core psychopathological symptoms in patients with schizophrenia suggest that their sense of self may be disturbed. A disturbance in predictive motor mechanisms may be the cause of such symptoms. Ten patients with schizophrenia and ten healthy right-handed control subjects opened and closed their hand. This movement was filmed with an MRI compatible video camera and projected online onto a monitor. BOLD contrast was measured with fMRI. The temporal delay between movement and feedback was parametrically varied. Participants judged whether or not there was a delay. Patients were less sensitive to these delays than a matched control group. Comparing neural activation between the two groups showed a reduced attenuation of movement-sensitive perceptual areas in patients with increasing delay and a higher activation in the putamen in controls. The results provide further evidence that impaired efference copy mechanisms may contribute to the pathogenesis of schizophrenia and its first rank symptoms.