It’s long been known that simply smiling makes people feel better and making an angry face can make people feel more angry. Thus some cosmetic surgeons speculated:
People with Botox may be less vulnerable to the angry emotions of other people
because they themselves can’t make angry or unhappy faces as easily. And because
people with Botox can’t spread bad feelings to others via their expressions,
people without Botox may be happier too.
We show that, during imitation of angry facial expressions, reduced
feedback due to BTX treatment attenuates activation of the left
amygdala and its functional coupling with brain stem regions
implicated in autonomic manifestations of emotional states. These
findings demonstrate that facial feedback modulates neural activity
within central circuitries of emotion during intentional imitation of
facial expressions. Given that people tend to mimic the emotional
expressions of others, this could provide a potential physiological
basis for the social transfer of emotion.