rTMS stimulation improves the facial mimicry and detection responses in an empathic emotional task

Facial expression detection and facial mimicry behavior in response to an empathic situation were analyzed in the present research. We supposed a “simulation mechanism” may be related to empathic response, and that it could be supported by prefrontal cortical structures. High frequency rTMS (repeated Transcranial Magnetic Stimulation) was applied to MPFC to induce an increased response to facial expression of emotions when subjects (N = 16) were required to empathize with the emotional stimuli. The stimulus valence was also varied (negative vs positive vs. neutral faces) to explore also the emotional content effect on empathic behavior. Autonomic (facial zygomatic and corrugator EMG subjective response) and detection (correct recognitions, CRs; RTs, response times) measures were found to be modulated by MPFC activity. Specifically, when prefrontal structures were activated (in comparison with sham effect and control site stimulation) an increased performance was observed in terms of increased CRs and reduced RTs for face recognition from one hand; of increased emotion-specific EMG response for the other hand. In fact, zygomatic muscle was more responsive in case of positive emotion (happiness), whereas corrugator activity was related to negative emotions (fear, anger, disgust). A higher effect was revealed for negative, and potentially aversive, faces in comparison respectively with positive and neutral faces. Finally, a direct correlation was found between the autonomic and detection measures. Taken together, these results suggest a “simulation mechanism” underlying empathic situations that includes both EMG and behavioral responses. This mechanism appears to be supported and regulated by MPFC area.