And when you use the "smile muscles" at the corners of your mouth, you change the direction of the blood flow inside your face in such a way that it causes the temperature of the blood to drop.

当你使用嘴角的“微笑肌肤肉”时，你改变了流进脸部血液的方向，用这种方式能降低血液的温度。

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For others the difference is very subtle and for others it only becomes noticeable when they smile and contract the muscles in their face.

对于其他人来说，这样的区别是非常小的，只有当她们微笑的时候对比她们脸部肌肉的时候才能看出来。

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Whenever we smile, nerves and muscles may transmit messages that turn on happiness centers in the brain, Laird speculates.

每当我们微笑时，神经和肌肉就会传递信息使大脑的快乐中心兴奋，莱尔德猜测说。

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You know, even some goes pass you on the street and you don't smile ostensibly you don't smile-- there are certain micro-muscles in your face that are moving that actually make you feel better.

即使路人与你擦身而过时，你没笑,表面上你没有笑-,但你面部的细微肌肉,会收缩，让你感觉更好。

哈佛公开课 - 幸福课课程节选

In research performed at the University of Clermont-Ferrand in France, subjects were asked to interpret real vs. fake smiles, while holding a pencil in their mouths to repress the muscles that help us smile.

FORBES: The Untapped Power Of Smiling

Such a smile, commonly referred to as a Duchenne smile, after the 19th century French neurologist who first described it, activates major muscles around the mouth and the eyes.

WSJ: Stress-Busting Smiles

By contrast, a standard social smile, which is sometimes called a Pan Am smile after the polite expression the former airline's stewardesses used to greet passengers, activates only the muscles around the mouth.

WSJ: Stress-Busting Smiles