Bilateral Transcranial Direct Stimulation Over the Primary Motor Cortex Alters Motor Modularity of Multiple Muscles

Jae Hyuk Lee, Yan Jin, Bum Chul Yoon

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) has been demonstrated to modulate the motor performance of both healthy individuals and patients with neuromuscular disorders. However, the effect of tDCS on motor control of multiple muscles, which is a prerequisite to change in motor performance, is currently unknown. Using dimensionality reduction analysis, we investigated whether bilateral tDCS over M1 modulates the coordinated activity of 12 muscles. Fifteen healthy men participated in this randomized, double-blind crossover study. Each participant received a 20-min sham and 2-mA stimulation bilaterally over M1 (anode on the right M1 and cathode on the left M1), with a minimum washout period of 4 days. Muscle activation and end-point kinematics were evaluated during a task where participants reached out to a marked target with non-dominant hand as fast as possible, before and immediately after tDCS application. We found decreased similarity in motor modularity and significant changes in muscle activation in a specific motor module, particularly when reaching out to a target placed within arm’s length and improved smoothness index of movement only following 2-mA stimulation. These findings indicate that clinicians and researchers need to consider the simultaneous effect of bilateral tDCS over M1 on multiple muscles when they establish tDCS protocol to change in motor performance of patients with neuromuscular deficits.

Original languageEnglish
Pages (from-to)474-488
Number of pages15
JournalJournal of Motor Behavior
Issue number4
Publication statusPublished - 2020 Jul 3

Bibliographical note

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©, Copyright © Taylor & Francis Group, LLC.


  • motor modularity
  • muscle coordination
  • primary motor cortex
  • reaching performance
  • transcranial direct stimulation

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience


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