Affiliations: Program in Physical Therapy, University of Minnesota,
Minneapolis, MN, USA | Laboratory for Noninvasive Brain Stimulation,
Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical
School, Boston, MA, USA
Note: [] Corresponding author: James R. Carey, Program in Physical
Therapy, MMC 388, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN
55455, USA. Tel.: +1 612 626 2746; E-mail: carey007@umn.edu
Abstract: Purpose. This study explored the effects of motor learning training
combined with repetitive transcranial magnetic stimulation (rTMS) on motor
performance in healthy subjects. Methods. Twenty-seven right-handed subjects were randomized to
three groups: ipsilateral rTMS (IS group), contralateral rTMS (CS group), and
sham rTMS (SS group). rTMS was applied for 10 minutes (1 Hz, 90% motor
threshold) prior to training. Training involved 10 minutes of finger tracking
with the right hand. Tracking performance was tested before, during and after
training. Results. Improvement in tracking performance over the
posttests was not significantly different between the CS and SS groups, whereas
it was significantly lower for the IS group compared to the SS group. No
difference was found across groups at retention tests. Conclusion. These findings indicate that rTMS interfered with
motor performance transiently when applied ipsilateral to the training hand and
had no effect when applied contralaterally. These results invite further work
to determine whether the disruptive effect of ipsilateral rTMS observed here in
healthy subjects, with presumably balanced interhemispheric inhibition, might
translate differently to subjects with abnormal interhemispheric inhibition
(stroke patients) in a way that disinhibits the ipsilesional hemisphere and
improves performance in the paretic hand.
Keywords: Repetitive transcranial magnetic stimulation, motor cortex, motor learning, interhemispheric inhibition
