Abstract
Action observation (AO) and motor imagery (MI) can have positive effects on motor learning and neurorehabilitation. Neuroimaging evidence indicates that AO and MI engage neural networks similar to those engaged during physical execution (PE). Studies examining combined AO and MI (AOMI) indicate that more robust effects may be facilitated when engaging in both methods simultaneously, compared to AO or MI alone. Hence, AOMI training could potentially provide a more efficient method to promote cortical reorganization. The current study evaluated the effect of AOMI training using a transcranial magnetic stimulation (TMS)-evoked thumb movement paradigm. Previous studies found that PE and MI training led to plasticity-related changes in the direction of TMS-evoked thumb movements. In the present study, TMS was delivered to left primary motor cortex to evoke thumb movements at baseline and after each of 5 blocks of AOMI training. The training involved participants repeatedly watching a video of a thumb movement in the opposite direction (flexion or extension) to their dominant baseline TMS-evoked thumb movement, while simultaneously imagining the feeling (kinesthetic MI) of making the movement they observed. Preliminary results (n=10) show a significant change in the proportion of TMS-evoked thumb movements in the direction of training after 4 blocks (1200 trials) of AOMI training. These changes are comparable to previous data showing changes arising from MI only training. Overall, these initial results indicate that AOMI can induce motor cortical reorganization after exposure to a sufficient amount of training, but may not be more efficient than MI alone.
