3 research outputs found
Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans
Optimization of motor performance is of importance in daily life, in relation to recovery following injury as well as for elite sports performance. The present study investigated whether transcutaneous spinal direct current stimulation (tsDCS) may enhance voluntary ballistic activation of ankle muscles and descending activation of spinal motor neurons in ableâbodied adults. Fortyâone adults (21 men; 24.0 ± 3.2 years) participated in the study. The effect of tsDCS on ballistic motor performance and plantar flexor muscle activation was assessed in a doubleâblinded shamâcontrolled crossâover experiment. In separate experiments, the underlying changes in excitability of corticospinal and spinal pathways were probed by evaluating soleus (SOL) motor evoked potentials (MEPs) following singleâpulse transcranial magnetic stimulation (TMS) over the primary motor cortex, SOL Hâreflexes elicited by tibial nerve stimulation and TMSâconditioning of SOL Hâreflexes. Measures were obtained before and after cathodal tsDCS over the thoracic spine (T11âT12) for 10 min at 2.5 mA. We found that cathodal tsDCS transiently facilitated peak acceleration in the ballistic motor task compared to sham tsDCS. Following tsDCS, SOL MEPs were increased without changes in Hâreflex amplitudes. The shortâlatency facilitation of the Hâreflex by subthreshold TMS, which is assumed to be mediated by the fast conducting monosynaptic corticomotoneuronal pathway, was also enhanced by tsDCS. We argue that tsDCS briefly facilitates voluntary motor output by increasing descending drive from corticospinal neurones to spinal plantar flexor motor neurons. tsDCS can thus transiently promote withinâsession CNS function and voluntary motor output and holds potential as a technique in the rehabilitation of motor function following central nervous lesions