Effects of transspinal electrical stimulation estimated by transcranial magnetic stimulation

The current study aimed to demonstrate the specifics of the effect of anodal transspinal direct current stimulation (tsDCS) applied at the level of the cervical spinal cord thickening on the corticospinal system of a healthy person. The study involved 54 healthy adults aged 22+/-4 years. Our results showed that application of a 1l-minute anodal tsDCS at the level of the cervical spinal cord C7-Th1 with a current value of 1.5 mA has an effect on the muscles of the upper limbs. In particular, the effect of tsDCS is a decrease in motor evoked potentials (MEP) amplitude immediately after stimulation, and an increase in amplitude 15 minutes after stimulation. These results can be explained by the fact that tsDCS induces changes in the excitability of the corticospinal tract, thereby causing suprasegmental effects in the brain and brainstem. The statistical analysis demonstrated that the dynamics of MEP amplitudes differs between groups receiving anodal tsDCS and sham stimulation. Altogether, these findings point to the need for further research into the effects of tsDCS on the upper limbs, as the effects of tsDCS are often limited to studies of the lower limbs. The current study showed that the noninvasive cervical tsDCS can modulate the excitability of the corticospinal tract, and thus can probably have a positive effect on the production of motor skills.