TMS provides evidence of effector-specific premotor contributions to action interpretation


Although it is well established that regions of ventral premotor cortex (vPMC) are active during action observation, it remains controversial whether that activation plays a causal role in action interpretation. In the experiment reported here, we used offline continuous theta-burst stimulation (cTBS) to investigate this question. All participants received offline cTBS to the hand area of vPMC in one session and to the lip area in a separate session, and after each session performed an action-interpretation task in which half of the trials were pantomimed hand actions and half were pantomimed mouth actions. The results show that participants were less accurate in interpreting hand actions after receiving cTBS over the hand area than after receiving stimulation over the lip area, and less accurate at interpreting lip actions after receiving cTBS over the lip area than after receiving stimulation over the hand area. This double dissociation provides evidence in support of the claim that somatotopically organized regions of vPMC contribute causally to action interpretation, and the claim that action production and action interpretation rely on overlapping mechanisms. In more general terms, they reveal an involvement of the motor system in more sophisticated cognitive processes than has hitherto been demonstrated.

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