' S3 M% P% w R2 \! @9 _tvb now,tvbnow,bttvb進化論作者達爾文留意到人類表情與內心的關係,把這個肌肉活動與心理的互動現象串連起來:「The free expression by outward signs of an emotion intensifies it... skeletal muscle feedback from facial expressions plays a causal role in regulating emotional experience and behavior.」這個劃時代的Facial Feedback Hypothesis理論,到本世紀終於透過神經傳遞和分子反應科技得到證實,為大腦的可塑性neuroplasticity提供基礎。