P253 Neurophysiological mechanisms of transcranial direct-current stimulation-enhanced motor learning in healthy children

Abstract

Introduction Transcranial direct-current stimulation (tDCS) enhances motor learning in adults. We recently demonstrated robust effects in children. Unique tDCS effects may occur in the developing brain, confounding trial design in disabled children. We investigated the neurophysiology underlying tDCS-induced enhancement of motor learning. Methods 24 healthy right-handed children trained their left hand on the Purdue Pegboard Test (PPT) over 3 consecutive days while receiving primary motor cortex (M1) tDCS as: (1) contralateral 1 mA anodal, (2) ipsilateral 1 mA cathodal, (3) ipsilateral 2 mA cathodal or (4) sham. Stimulation was applied for the first 20 min of training each day. Transcranial magnetic stimulation explored bihemispheric M1 neurophysiology at baseline and post-training. Outcomes included cortical excitability, short-interval intracortical inhibition (SICI), intracortical facilitation, cortical silent periods (cSP) and interhemispheric inhibition (IHI). Results All active tDCS paradigms enhanced motor learning by approximately 40% compared to sham ( p r = −0.541) and positively correlated with SICI ( r = 0.420). Anodal tDCS increased cortical excitability ( p p p p Conclusions tDCS enhancement of motor learning in healthy children is associated with changes in cortical excitability, intracortical and transcallosal inhibition. Intracortical inhibition may be associated with lower motor function. Elucidation of tDCS mechanisms of neuromodulation will inform optimization of stimulation parameters when applying tDCS to children with cerebral palsy.