Self-monitoring of social facial expressions in the primate amygdala and cingulate cortex

Abstract

Keeping track of self-executed facial expressions is essential for the ability to correctly interpret and reciprocate social expressions. However, little is known about neural mechanisms that participate in self-monitoring of facial expression. We designed a natural paradigm for social interactions where a monkey is seated in front of a peer monkey that is concealed by an opaque liquid crystal display shutter positioned between them. Opening the shutter for short durations allowed the monkeys to see each other and encouraged facial communication. To explore neural mechanisms that participate in self-monitoring of facial expression, we simultaneously recorded the elicited natural facial interactions and the neural activity of single neurons in the amygdala and the dorsal anterior cingulate cortex (dACC), two regions that are implicated with decoding of others' gestures. Neural activity in both regions was temporally locked to distinctive facial gestures and close inspection of time lags revealed activity that either preceded (production) or lagged (monitor) initiation of facial expressions. This result indicates that single neurons in the dACC and the amygdala hold information about self-executed facial expressions and demonstrates an intimate overlap between the neural networks that participate in decoding and production of socially informative facial information.