Abstract:
Bilateral motor training is a useful method for modifying corticospinal excitability. The
effects of bilateral movement that are caused by artificial stimulation on corticospinal excitability
have not been reported. We compared motor-evoked potentials (MEPs) of the primary motor
cortex (M1) after conventional bilateral motor training and artificial bilateral movements generated
by electromyogram activity of abductor pollicis brevis (APB) muscle-triggered peripheral nerve
stimulation (c-MNS) and transcranial magnetic stimulation of the ipsilateral M1 (i-TMS). A total of
three protocols with different interventions—bilateral finger training, APB-triggered c-MNS, and
APB-triggered i-TMS—were administered to 12 healthy participants. Each protocol consisted of
360 trials of 30 min for each trial. MEPs that were induced by single-pulse TMS, short-interval
intracortical inhibition (SICI), and intracortical facilitation (ICF) that were induced by paired-pulse
TMS were assessed as outcome measures at baseline and at 0, 20, 40, and 60 min after intervention.
MEP amplitude significantly increased up to 40 min post-intervention in all protocols compared to
that at the baseline, although there were some differences in the changing pattern of ICF and SICI in
each protocol. These findings suggest that artificial bilateral movement has the potential to increase
the ipsilateral cortical excitability of the moving finger.
