A mirror mechanism for smiling in the anterior cingulate cortex.

It was recently proposed that the neural substrate mediating smile production might play a key role also in the recognition of others' smile. This hypothesis, however, has been challenged by difficulties in eliciting ecological smiling in standard laboratory settings. Here we report of a case where these difficulties were overcome by combining electrical stimulation and intracranial electroencephalogram recording in a patient with drug-resistant focal epilepsy. The stimulation of the pregenual anterior cingulate cortex (pACC) elicited a smiling facial expression. The same leads exploring pACC showed an increase of gamma band activity (50-100 Hz) during the observation of video-clips depicting actors laughing, relative to video-clips depicting actors crying or producing a neutral expression. These findings indicate that both smile production and recognition are encoded in pACC and further support the role of this region in social cognition. (PsycINFO Database Record (c) 2017 APA, all rights reserved).