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This Article Full Text Full Text (PDF) eTables All Versions of this Article: ptj.20090075v1 90/3/398    most recent Submit a response Alert me when this article is cited Alert me when Rapid Responses are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Williams, J. A. Articles by Fregni, F. Search for Related Content PubMed PubMed Citation Articles by Williams, J. A. Articles by Fregni, F. Related Collections Adaptive/Assistive Devices Electrotherapy Therapeutic Exercise Motor Control and Motor Learning Neurology/Neuromuscular System: Other Social Bookmarking                      What's this?

Interhemispheric Modulation Induced by Cortical Stimulation and Motor Training

J.A. Williams, MA, is Research Assistant, Department of Neurology, Harvard Medical School, Boston, Massachusetts.
A. Pascual-Leone, MD, PhD, is Associate Professor, Department of Neurology, Harvard Medical School.
F. Fregni, MD, PhD, MPH, is Assistant Professor, Department of Neurology, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215 (USA). Dr Fregni also is Director, Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital, Harvard Medical School.

Address all correspondence to Dr Fregni at: Fregni.Felipe{at}mgh.harvard.edu.

Background: Interhemispheric inhibition might be a beneficial cortico-cortical interaction, but also might be maladaptive in people with neurological disorders. One recently revisited technique that has been shown to be effective in improving motor function in people with stroke using interhemispheric modulation is transcranial direct current stimulation (tDCS).

Objective: The aim of this study was to investigate the effects of tDCS combined with unilateral motor training with contralateral hand restraint on interhemispheric inhibition between the dominant and nondominant hemispheres of the brain and on motor performance in participants who were healthy.

Design: This was a double-blind, prospective, single-center study with participants who were healthy.

Methods: Twenty participants who were healthy were randomly assigned to receive either active or sham tDCS of the primary motor cortex (M1) bilaterally combined with unilateral motor training and contralateral hand restraint. A blinded rater assessed motor function and cortical excitability, including assessment of transcallosal inhibition (TCI).

Results: There was a larger increase in motor performance in the nondominant hand for the active tDCS group compared with the sham tDCS group. In addition, a decrease in cortical excitability in the dominant hemisphere and a decrease in TCI from the dominant to nondominant hemisphere were observed for the active tDCS group only. The TCI decrease in the active tDCS group was correlated with motor performance improvement for the nondominant hand.

Limitations: Limitations of this study included missing the effect of intracortical inhibition due to a floor effect, not using the optimal tDCS montage, and not being able to assess the effects of other variables such as gender due to the small sample size.

Conclusions: The results indicate that tDCS enhances the effects of unilateral motor training and contralateral hand restraint on motor function, and this benefit is associated with a different mechanism of action characterized by bihemispheric modulation in which TCI from the dominant to the nondominant hemisphere is decreased. Transcranial direct current stimulation might be a useful tool to enhance the motor effects of constraint-induced movement therapy.

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