Facial gestures are enacted through a cortical hierarchy of dynamic and stable codes.

Abstract

Facial gestures are one fundamental set of communicative behaviors in primates, generated through the dynamic arrangement of many fine muscles. Anatomy shows that facial muscles are under direct control from multiple cortical regions, and studies of patients with focal lesions suggest that lateral frontal cortices control voluntary movements and medial emotional expressions. By directly measuring single-neuron activity from both sets of areas, we found that lateral and medial cortical face motor regions encode both types of gestures. They do so through area-specific temporal activity patterns, distinguishable well prior to movement onset. Our results show that cortical regions projecting in parallel downstream form a continuum of gesture coding, from dynamic to temporally stable, to produce socially appropriate motor outputs during communication.