Mode of hand training determines cortical reorganisation: A randomized controlled study in healthy adults

Objective: To evaluate two commonly used forms of hand training with respect to influence on dexterity and cortical reorganization. Subjects: Thirty healthy volunteers (mean age 24.2 years). Methods: The subjects were randomized to 25 min of shaping exercises or general activity training of the non-dominant hand. The dexterity and the cortical motor maps (number of excitable positions) of the abductor pollicis brevis muscle were evaluated pre- and post-training by the Purdue Peg Board test and transcranial magnetic stimulation, respectively. Results: After shaping exercises the dexterity increased significantly (p <= 0.005) for both hands, mostly so in the non-dominant hand. The cortical motor map of the abductor pollicis brevis muscle shifted forwardly into the pre-motor area without expanding. After general activity training, no significant improvements in dexterity were found for the non-dominant hand. The cortical motor map of the non-dominant abductor pollicis brevis muscle expanded significantly (p = 0.03) in the posterior (sensory) direction. Conclusion: These results indicate that shaping exercises, but not general activity training, increase dexterity of the trained non-dominant hand in parallel with a shift of location of active transcranial magnetic stimulation positions. Shifts of active cortical areas might be important for the interpretation of brain plasticity in common behavioural tasks.