Article

Training-related improvements in motor function are associated with
changes in movement representation of the primary motor cortex (M1). In healthy
individuals, transcranial magnetic stimulation (TMS) of M1 delivered in a strict
temporal relationship (Hebbian-type stimulation) during execution of movements
enhances these effects and is superior to random stimulation. The authors tested whether training combined with Hebbian-type M1 stimulation
enhances M1 reorganization in patients with stroke.
METHODS: Six patients with
chronic stroke participated in the study. Patients executed robot-assisted wrist
extension movements at 0.2 Hz frequency while subthreshold repetitive TMS was
applied over M1 in a strict temporal relationship to the training movements. TMS
was applied to either the affected hemisphere (contralateral M1) or the
nonaffected hemisphere (ipsilateral M1) at 0.1 Hz. Intervention-related changes
in motor maps and intracortical excitability were measured using TMS. RESULTS:
Training alone or combined Hebbian-type stimulation of either M1 resulted in
differential effects on motor maps and intracortical inhibition. Shifts in motor
maps were associated with increases in intracortical excitability. In contrast to
previous results for healthy participants, the inhibitory effect of ipsilateral
M1 Hebbian-type stimulation was not present, and the facilitatory effect of
contralateral M1 stimulation was more subtle. CONCLUSIONS: Hebbian-type
stimulation is feasible in patients poststroke and induces map reorganization and
associated decreases in GABAergic inhibition. However, because TMS protocols have
a different effect on motor reorganization in the injured brain and may depend on
location of the lesion, protocols need to be tailored to the patient's pathology.

Langue : ANGLAIS