Prolonged motor skill learning--a combined behavioural training and θ burst TMS study

To assess the behavioural effects of prolonged motor practice in healthy volunteers, and the specific impact of inhibiting different motor-related brain regions in the late phase of motor learning using continuous theta burst transcranial magnetic stimulation (cTBS).

Twelve subjects trained their non-dominant arm in eight arm motor tasks (Arm Ability Training, AAT) once a day for three weeks (16 sessions). During the last four days, training was performed before and after applying cTBS to either M1, S1, SMA, or PMC.

The AAT induced substantial and robust motor learning for the trained arm with variations across tasks. Considerable motor learning was also observed in the non-trained dominant arm with remarkably similar variations across tasks, suggesting that practise improved common underlying sensorimotor capacities (abilities) in addition to effector-specific effects. When applied after prolonged training, inhibitory cTBS showed no detrimental effects on motor performance/learning; M1 cTBS even improved performance in a labyrinth task.

Prolonged training with the non-dominant arm led to profound motor learning across abilities with transfer to the non-trained dominant arm. Unlike during early stages of motor learning, no detrimental effect of cTBS over M1, S1, PMC, or SMA could be substantiated after prolonged motor practice.