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

To evaluate two commonly used forms of hand training with respect to influence on dexterity and cortical reorganization.

Thirty healthy volunteers (mean age 24.2 years).

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.

After shaping exercises the dexterity increased significantly (p < or = 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.

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.