The investigators will compare the effects on the nociceptive processing of healthy volunteers of cervical and lumbar tsDCS. This study will be a double-blinded, sham-controlled, cross-over trial. Each participant will undergo two experimental sessions (anodal cervical tsDCS and sham lumbar tsDCS vs. sham cervical tsDCS and anodal lumbar tsDCS), separated by at least one week.
Several studies have demonstrated that direct currents delivered through the skin at the level of the lumbar spinal cord can influence spinal cord function. In human volunteers, anodal lumbar transcutaneous spinal direct current stimulation (tsDCS) alters spinal processing of nociceptive inputs. Whether cervical tsDCS is able to do the same is less well known.