Trans-spinal direct current stimulation affects the corticospinal system but does not affect motor skills

Abstract

Abstract The purpose of the study was to investigate the effect of anodal trans-spinal direct current stimulation (tsDCS) applied at the level of cervical spinal cord enlargement (C7–Th1 segments) on corticospinal system excitability and motor skills. The study involved 54 healthy adults aged 21.19 ± 3.2 years. Our results showed that the application of an anodal tsDCS (11-minute, 1.5 mA) affected the first dorsal interosseous muscle of the index finger when measured by motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation of the primary motor cortex. The effect of tsDCS manifested as a decrease in MEP amplitude immediately following stimulation and an increase in amplitude 15 minutes after it. The statistical analysis demonstrated that the dynamics of MEP amplitudes differed between groups receiving anodal tsDCS and sham stimulation, although anodal tsDCS did not affect motor skills production. The ability of an individual after receiving anodal tsDCS to coordinate their fingers and manipulate objects effectively in the nine-hole peg test and pressing a key in response to visual stimulus in the serial reaction time task did not differ from the sham stimulation. We also found that the motor learning factor during stimulation did not affect the change in MEP amplitude.