title: Suppression of ipsilateral motor cortex facilitates motor skill learning.
abstract: The primary motor cortex (M1) plays a critical role in early aspects of motor skill learning. Given the notion of inter-hemispheric competition, unilateral disruption of M1 may increase excitability of the unaffected motor cortex and thus improve motor learning with the ipsilateral hand. We applied slow-frequency repetitive transcranial magnetic stimulation (rTMS) before the initiation of practice of a simple motor skill. Participants were randomly divided into three stimulation groups: (i) ipsilateral M1; (ii) contralateral M1; and (iii) Cz (control site). The mean execution time and error rate were recorded in four sessions distributed over 2 days. Disruption of M1 with rTMS slowed down skill acquisition with the contralateral hand, albeit non significantly, but paradoxically enhanced learning with the ipsilateral hand. This was evidenced by a significant decrease of execution time at the end of day 1 in the group that received rTMS over the ipsilateral M1 compared with both control groups (Cz and contralateral M1 stimulation). This supports the notion of inter-hemispheric competition and provides novel insights that may be applicable to neurorehabilitation.
authors.affiliation: Behavioral Neurology Unit, Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.
authors.forename: Masahito
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Hugo
authors.initials: H
authors.lastname: Théoret
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual-Leone
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D009433:Neural Inhibition; D050781:Transcranial Magnetic Stimulation