Effects of noninvasive anodal transspinal direct current stimulation of the cervical segments on motor learning in healthy subjects

The aim of this study was to estimate the effect of noninvasive anodal transpinal spinal direct current stimulation (a-tsDCS) at the C7-Th1 level of the spinal cord (C7-Th1) on the corticospinal system and on the modulation of motor skills. The effect of tsDCS was assessed using motor-evoked potentials (MEP) from transcranial magnetic stimulation (TMS) in the primary motor cortex (M1). The study was done on 54 healthy subjects aged 22+/-4 years. Our results showed that the application of 11-minute a-tsDCS at the cervical spinal cord level with a current of 1.5 mA had no effect on the improvement in manual dexterity in the 9-HPT test and had no effect on visual-motor association learning in the SRT test. Moreover, the factor of motor learning during stimulation does not affect the MEP from TMS. Overall, these results point to the need to develop further protocols for the effects of tsDCS on upper limb motor skills.