Noninvasive DC stimulation on neck changes MEP.

Direct current stimulation (DCS) has been known as a noninvasive method for modulating neural activity. We estimated the effects of noninvasive cutaneous DCS applied to the cervical region on corticospinal excitability and segmental sensorimotor excitability. The motor-evoked potential amplitudes and the parameters of the Hoffmann reflex were measured before, immediately after, 1 h after, and 2 h after DCS. In this study, we found that noninvasive cervical application of DCS could increase the motor-evoked potential amplitudes which reflected corticospinal tract excitability. This effect of DCS remained for 2 h after stimulation had ceased. These findings suggest DCS might be a noninvasive and effective tool for corticospinal tract excitation.