A transcranial magnetic stimulation study of corticospinal excitability during the observation of meaningless, goal-directed, and social behaviour

Abstract

The effects of action observation on cortical processes have typically been interpreted in the context of so-called "mirror systems" (i.e., brain regions active during both the experience and observation of behaviour, emotion, or sensation), and viewed as subserving social cognition via a self-other matching mechanism. If such cortical processes do indeed facilitate social understanding, then cortical activity during action observation might be further enhanced when observing behaviour embedded within a social, interactive context. Transcranial magnetic stimulation (TMS) was administered to 27 healthy adults, and corticospinal excitability (CSE), which is a putative measure of the mirror system, was examined during the observation of (1) meaningless behaviour, (2) goal-directed behaviour, and (3) social behaviour. Although CSE was enhanced during the observation of both goal-directed and social behaviour, there was no difference between the two. These findings suggest that while the putative human mirror system is responsive to goal-directed behaviour, it may not be more responsive to behaviour that occurs within a social context.