Mirror neuron system dysfunction in schizophrenia and its clinical implication

Since the discovery of mirror neuron system, several neurophysiological and neuroimaging studies showed that the mirror neuron system might have a role in understanding other people's actions and intentions with automatic simulation of their actions. Moreover, some studies suggested that mirror neurons have a broader role in social cognition including understanding others' emotions and empathy. It has not been proved, however, whether the mirror neuron system is necessarily involved in empathy processes. In the domain of social cognition deficits, it is important to investigate the involvement of mirror neuron system dysfunction in psychosis such as schizophrenia. Using magnetoencephalography, we examined whether antipsychotic-free schizophrenia patients displayed mirror neuron system dysfunction during observation of biological motion (jaw movement). Compared with normal controls, the patients with schizophrenia had fewer components of both the waveform and equivalent current dipole, suggesting aberrant brain activity resulting from dysfunction of the right inferior parietal cortex. They also lacked the changes of alpha band and gamma band oscillation seen in normal controls, and had weaker phase locking factors and gamma-synchronization predominantly in right parietal cortex. This finding demonstrated that untreated patients with schizophrenia exhibited aberrant mirror neuron system function based on the right inferior parietal cortex, which is characterized by dysfunction of gamma-synchronization.