Motor imagery while judging object-hand interactions.

Because corticospinal excitability, as assessed with transcranial magnetic stimulation, has been repeatedly shown to increase during motor imagery, we used this approach to determine whether appreciating object-hand interactions involves motor imagery. Corticospinal excitability was measured in nine healthy participants who were asked to decide whether a hand presented in a given posture was compatible with the use of an object. The control task consisted in deciding whether two hands were in the same posture; a dimming task was used to determine the baseline. We found a significant increase in corticospinal excitability while judging object-hand interactions in comparison with the two other tasks. This finding suggests that predicting the consequences of an action involves implicit motor imagery.