Waszak, F. 1 , Schuetz-Bosbach, S. 2 , Weiss, C. 2 & Ticini, L. 2
1 LPP, CNRS, Paris, France
2 MPI CBS, Leipzig, Germany
Our brain is able to recognize action sounds by representing them as motor events. Previous studies have demonstrated somatotopic activation of the listener's motor cortex during perception of the sound of over-familiar motor acts. The present experiments asked (i) how the motor system is activated by the sounds of actions that are newly acquired, and (ii) whether action-related sounds are represented with reference to extrinsic features related to action goals rather than with respect to lower-level intrinsic parameters related to the specific movements. Transcranial magnetic stimulation (TMS) was used to measure the correspondence between auditory and motor codes in the listener’s motor system. We compared the corticomotor excitability in response to the presentation of auditory stimuli before and after a short perceptuomotor training, in which voluntary actions were associated with arbitrary perceivable consequences void of a motoric meaning before training. Novel auditory-motor representations became manifest very rapidly. Indeed, passive listening to newly learnt action-related sounds activated a precise motor representation that took into account the variable contexts to which the individual was exposed to. Our results suggest that the human brain embodies a higher-order auditomotor representation of perceived actions, which is muscle-independent and corresponds to the action’s goals.