Changes in corticospinal excitability during observation of walking in humans

To address whether the passive observation of walking would induce an increase in motor cortical excitability, we examined the responses of motor-evoked potential elicited by transcranial magnetic stimulation in the tibialis anterior and soleus muscles as the participants observed naturally performed walking. Motor-evoked potentials in these muscles were significantly increased during the observation of walking throughout the entire step-cycle periods, but not during specific step periods. These findings indicate that cortical excitability can be increased not only during the observation of voluntary hand/arm movements, but also during the observation of automatic movements such as walking. It is also suggested that the present results may reflect the increased cortical excitability during the entire walking cycle.