Visual selectivity and motor role of action observation/execution neurons in macaque ventral premotor cortex

Summary Neurons responding during action execution and action observation were discovered in the ventral premotor cortex three decades ago. However, neither the minimum visual features nor the motor involvement of Action Observation/Execution Neurons (AOENs) have been revealed at present. We investigated the minimal visual stimulus for activation and the involvement in motor behavior of AOENs in ventral premotor area F5c of four macaques. The large majority of AOENs showed highly phasic responses during the action videos, and also responded to an abstract shape moving towards but not interacting with an object, even when the shape moved on a scrambled background, implying that most AOENs in F5c do not require the perception of causality or a meaningful action. Additionally, electrical microstimulation of AOEN sites invariably elicited motor responses and frequently interfered with visually guided object grasping. Our findings suggest that an important role of F5c AOENs in visuomotor control during object grasping.