Perspective-dependent activation of frontoparietal circuits during the observation of a static body effector.

The perspective from which body-related stimuli are observed plays a fundamental role in modulating cerebral activity during the processing of others' bodies and actions. Previous research has shown perspective-dependent cerebral responses during the observation of both ongoing actions and static images of an acting body with implied motion information, with an advantage for the egocentric viewpoint. The present high-density EEG study assessed event-related potentials triggered by the presentation of a forearm at rest before reach-to-grasp actions, shown from four different viewpoints. Through a spatiotemporal analysis of the scalp electric field and the localization of cortical generators, our study revealed overall different processing for the third-person perspective relative to other viewpoints, mainly due to a later activation of motor-premotor regions. Since observing a static body effector often precedes action observation, our results integrate previous evidence of perspective-dependent encoding, with cascade implications on the design of neurorehabilitative or motor learning interventions based on action observation.