Facilitation of corticospinal excitability. The increase in MEP amplitude after VR wrist exercise following tDCS (A) was greater and sustained for 20 min after exercise compared with the three other conditions (B,C,D) in healthy volunteers and other two conditions (B,C) in stroke patients (***P < 0.001, **P < 0.01, *P < 0.05). P value from the post hoc analysis with Bonferroni correction. Error bars indicate standard errors of the mean (SEM). MEPs, motor evoked potentials, VR, virtual reality, tDCS, transcranial direct current stimulation.