Cortical Excitability Changes after Repetitive Self-regulated vs. Tracking Movements of the Hand

摘要

In stroke rehabilitation, the optimal training parameters for re-gaining impaired hand function are unknown. Examining cortical reorganization in normals during different training paradigms could aid in developing these optimal parameters. Previous work using imaging techniques has shown differences in brain activation between self-regulated movements (i.e. movement timing and amplitude determined by the subject) and tracking movements (i.e. movement timing and amplitude goals specified) of the index finger in both normals and stroke patients. The goal of this study is to use TMS to compare single session modulation of corticospinal excitability and short-interval intracortical inhibition (ICI) induced by two different training methods: repetitive self-regulated and repetitive tracking movements in a finger flexion/extension task that mimics a functional grasp and release. No significant changes in resting motor threshold (RMT) or recruitment curve were found. In the extensor digitorum communis (EDC) muscle, there tended to be a decrease in ICI after self-regulated practice and increase after tracking practice when ICI was measured using a conditioning stimulus (CS) intensity of 60% RMT. At CS intensity of 80% RMT, there tended to be a decrease in EDC ICI after both types of tasks. In the flexor digitorum superficialis (FDS) muscle, there was a significant interaction effect as FDS ICI remained stable or slightly increased after self-regulated practice and decreased after tracking practice at CS intensities of 60 and 80% RMT. The training seems to have an opposite effect on the FDS and EDC, perhaps because the EDC is a prime mover. This implies that precision training could produce an increase in inhibition in the primary muscle and a decrease in the antagonist.