Article

Long-term changes in the motor cortex can be induced by
practicing motor tasks with simultaneous application of peripheral nerve
stimulation. This combination may augment motor rehabilitation after stroke but
has been used primarily during contraction of the affected hand. The authors
tested the effect of a right hand movement that electrically stimulated left hand
contraction on right motor cortex excitability. METHODS: Three tasks were used in
15 healthy subjects--a motor and stimulation task (MS(task)), stimulation only
task (S(task)), and motor only task (M(task)). The MS(task) consisted of
isometric thumb abduction of the right hand that triggered paired electrical
stimulation of the left abductor pollicis brevis (APB) and first dorsal
interosseus (FDI) motor points. The S(task) was performed 1 week later and
matched the stimulation received in the MS(task). The M(task) was performed as a
control. Transcranial magnetic stimulation applied to the right motor cortex
assessed corticospinal excitability, short latency intracortical inhibition, and
intracortical facilitation of the FDI and APB before, immediately after, and 30
minutes after task performance. RESULTS: Corticospinal excitability increased in
the FDI and APB following the MS(task) but not following the S(task) or M(task).
The increased excitability present 30 minutes after the MS(task) also correlated
with excitability measures recorded 1 week later. CONCLUSION: A bilateral motor
and electrical stimulation task can drive persistent adaptation within the
corticospinal system. Hemiplegic subjects who have poor voluntary movement of the
affected hand may be able to contract the unaffected hand to activate and train
homologous movements.

Langue : ANGLAIS