Use-dependent plasticity in human primary motor hand area:Synergistic interplay between training and immobilisation

Abstract

Training and immobilization are powerful drivers of use-dependent plasticity in human primary motor hand area (M1HAND). Here we used transcranial magnetic stimulation to clarify how training and immobilisation of a single finger interact within M1HAND. Healthy volunteers trained to track a moving target with a finger for one week. The tracking skill acquired with the trained finger was transferred to a non-trained finger of the same hand. The cortical representations of the trained and non-trained finger muscle converged in proportion with skill transfer. Finger immobilisation alone attenuated the corticomotor representation and pre-existing tracking skill of the immobilized finger. The detrimental effects of finger immobilization were blocked by concurrent training of the non-immobilized finger. Conversely, immobilization of the non-trained fingers accelerated learning during the first two days of training. The results provide novel insight into use-dependent cortical plasticity, revealing synergistic rather than competitive interaction patterns within M1HAND.