Abstract
The mirror neuron system is thought to underlie the human ability to recognise the actions and gestures of others. It does so by providing a neural mechanism through which a perceived action can be directly matched with its corresponding representation within the observer's own motor repertoire. For this direct matching mechanism to mediate action understanding, a subset of mirror neurons should be more active when perceived and executed actions are identical, relative to when they are different. This strict correspondence has been demonstrated in monkeys, but the degree of correspondence required for activation of human mirror areas remains unclear. Here, we used fMRI to determine if areas within the mirror system are more active during the observation of matching (congruent) hand gestures compared to those that are non-matching (incongruent). Participants performed a series of pantomimed hand actions, while simultaneously observing either a congruent or incongruent action in separate, counterbalanced blocks. Crucially, the observed actions were irrelevant to participants, so any correspondence between observed and executed actions was incidental. Our analysis revealed that, while performing a specific action, particular nodes within the human mirror system were more active during the perception of congruent, relative to incongruent, actions. These findings indicate that areas within the human mirror system do indeed demonstrate a strict correspondence between observed and executed actions. We conclude that these mirror areas may be critical in the direct matching process that underlies action recognition.