Denervation of frown muscles with botulinum toxin disrupts facial feedback to central circuitry of emotion

Background: Given that people mimic the emotional expressions of others, feedback from facial muscles has been suggested to play a role in socially-induced affect. Imitation of facial emotion patterns engages limbic regions such as the amygdala which has strong connections to autonomic brainstem regions. Facial feedback could therefore modulate activation of the amygdala and its participation in autonomic manifestations of emotional states. We tested this hypothesis by investigating the neural correlates of intentional facial mimicry after peripheral denervation of emotionally expressive face muscles via botulinum toxin (BTX).