臨床におけるミラーニューロン―特に心的側面について

Mirror Neuron System Dysfunction in Schizophrenia and its Clinical Implication

ミラーニューロンシステムは，模倣や他者行為の理解に重要な役割を果たすだけでなく，他者の行為の意図の理解，そして他者の感情理解や共感などの社会認知に重要な役割を果たすという見解が提案されている。この社会認知という側面で，精神障害例の示す行動異常とミラーニューロンシステム異常の関係を探る研究は今後重要と思われる。この中で，統合失調症群におけるミラーニューロンシステム応答異常に関する研究を紹介した。統合失調症で認められた右頭頂葉下部領域ないしは上側頭回後部における高周波ミラーニューロンシステム応答の質的な異常は，自我障害をはじめとする異常体験と社会的コミュニケーション障害を説明できる可能性があることが示唆された。

Abstract

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.