Transcranial magnetic stimulation studies of the human mirror neuron system

Abstract

In a portion of the premotor area of the macaque brain named F5 (human homologue of Brodmann's Area 44), there are neurons that are called “mirror neurons”, which fire when a primate performs or observes another person/animal performing a goal-oriented action. These neurons are active when performing and observing the same action, hence the term is “action observation/execution matching system”. This system may be a fundamental component of imitation, learning and social behavior since observing and understanding the actions of others is a way to understand their intentions and motivations. This paper will review studies that were recently conducted in our laboratory using transcranial magnetic stimulation (TMS) to investigate the characteristics and specificity of this action observation/execution matching system in humans. In this series of studies, we addressed the following issues: effects of (1) visual-experience (i.e., when the subjects observe natural versus unnatural actions of their own hands or of other unknown hands), (2) perspective-taking, and (3) presence of a “goal” in action observation. The results show that motor facilitation during action observation is indeed due to the modulatory role of mirror neurons and studies of action observation have some implications in understanding social communication.