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Updated: Jun 25, 2026

Intracortical Inhibition Within the Primary Motor Cortex Can Be Modulated by Changing the Focus of Attention
Published on: September 11, 2017
Suppression of ipsilateral motor cortex facilitates motor skill learning.
Masahito Kobayashi1, Hugo Théoret, Alvaro Pascual-Leone
1Behavioral Neurology Unit, Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.
Disrupting one primary motor cortex (M1) with repetitive transcranial magnetic stimulation (rTMS) slowed learning with the opposite hand but enhanced motor skill acquisition with the same hand, supporting inter-hemispheric competition.
Area of Science:
- Neuroscience
- Motor Control
- Cognitive Science
Background:
- The primary motor cortex (M1) is crucial for early motor skill learning.
- Inter-hemispheric competition suggests that unilateral brain activity can influence the opposite hemisphere.
Purpose of the Study:
- To investigate if disrupting one M1 enhances motor learning in the ipsilateral hand via inter-hemispheric competition.
- To examine the effects of unilateral M1 disruption on motor skill acquisition.
Main Methods:
- Slow-frequency repetitive transcranial magnetic stimulation (rTMS) was applied to M1 (ipsilateral or contralateral) or a control site (Cz) before motor skill practice.
- Participants (n=?) practiced a simple motor skill over 2 days, with execution time and error rates recorded.
- Participants were randomly assigned to one of three stimulation groups.
Main Results:
- rTMS disruption of M1 led to non-significant slowing of skill acquisition in the contralateral hand.
- rTMS over the ipsilateral M1 significantly enhanced motor learning, indicated by reduced execution time by day 1, compared to control groups.
- This enhancement suggests increased excitability in the unaffected motor cortex.
Conclusions:
- Unilateral M1 disruption supports the theory of inter-hemispheric competition in motor learning.
- Findings offer novel insights for neurorehabilitation strategies aimed at improving motor function.
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