ヒトの聴覚ミラー・ニューロン、そして共感力

Empathy and the somatotopic auditory mirror system in humans
Gazzola V, Aziz-Zadeh L, Keysers C.
Curr Biol. 2006 Sep 19;16(18):1824-9.

　
How do we understand the actions of other individuals if we can only hear them? Auditory mirror neurons respond both while monkeys perform hand or mouth actions and while they listen to sounds of similar actions . This system might be critical for auditory action understanding and language evolution . Preliminary evidence suggests that a similar system may exist in humans . Using fMRI, we searched for brain areas that respond both during motor execution and when individuals listened to the sound of an action made by the same effector. We show that a left hemispheric temporo-parieto-premotor circuit is activated in both cases, providing evidence for a human auditory mirror system. In the left premotor cortex, a somatotopic pattern of activation was also observed: A dorsal cluster was more involved during listening and execution of hand actions, and a ventral cluster was more involved during listening and execution of mouth actions. Most of this system appears to be multimodal because it also responds to the sight of similar actions. Finally, individuals who scored higher on an empathy scale activated this system more strongly, adding evidence for a possible link between the motor mirror system and empathy.
　
猿の聴覚ミラーニューロンは行為を行うときも、他個体の同様の行為の音を聞いたときも活動する。ヒトでも同様の活動が左半球の側頭-頭頂-運動前野サーキットで見られた。運動前野では体部位表現があり、背側では腕の運動に関する音、腹側では口の運動に関する音に対して反応を示した。これらは運動を視覚で捉えたときにも同様の活動を示したので、マルチモーダルなものだと考えられる。ちなみに共感度テストで高い点を示した者はこれらの活動が強かったため、ミラー・システムと共感とのリンクが示唆される。