Introduction: Non-invasive brain stimulation has therapeutic potential in cerebral palsy but mechanisms remain unestablished in children. We have demonstrated that transcranial direct current stimulation (tDCS) can enhance motor learning in healthy and hemiparetic children. High-definition (HD-tDCS) may have additional capacity but is unstudied in pediatric populations. Motor maps generated with transcranial magnetic stimulation (TMS) may provide insight toward neuromodulation mechanisms.

Methods: AMPED (Accelerated Motor Learning in PEDiatrics) was a randomized, sham-controlled clinical trial (NCT03193580). Twenty-four healthy, right-handed children aged 12-18 years completed five consecutive days of training the Purdue Pegboard Test (PPT) randomized to contralateral M1 tDCS, HD-tDCS, or sham. Using neuronavigated robotic TMS, motor maps were obtained for 4 upper extremity muscles with outcomes of motor map area, volume, and center of gravity). Outcomes were repeated at 6-weeks.

Results: Both tDCS and HD-tDCS enhanced motor learning compared to sham with moderate, comparable effect sizes on Day 4 and Day 5 (tDCS d=0.960, d=0.655; HD-tDCS d=0.766, d=0.851) that persisted to 6 weeks. Training effects spilled over to the untrained hand and different motor tasks. Motor map area and volume were measurable with robotic TMS but did not change across time or treatment group. Procedures including tDCS, HD-tDCS and robotic TMS were safe and well tolerated with no adverse events or dropouts.

Conclusion/Discussion: Both tDCS and HD-tDCS can enhance motor learning in children with lasting effects. Robotic TMS motor mapping is feasible in children. These tools should advance clinical trials in disabled children with cerebral palsy.