Functional near-infrared spectroscopy maps cortical plasticity underlying altered motor performance induced by transcranial direct current stimulation

Bilal Khan, Timea Hodics, Nathan Hervey, George Kondraske, Ann M. Stowe, George Alexandrakis

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Transcranial direct current stimulation (tDCS) of the human sensorimotor cortex during physical rehabilitation induces plasticity in the injured brain that improves motor performance. Bi-hemispheric tDCS is a noninvasive technique that modulates cortical activation by delivering weak current through a pair of anodal-cathodal (excitation-suppression) electrodes, placed on the scalp and centered over the primary motor cortex of each hemisphere. To quantify tDCS-induced plasticity during motor performance, sensorimotor cortical activity was mapped during an event-related, wrist flexion task by functional near-infrared spectroscopy (fNIRS) before, during, and after applying both possible bi-hemispheric tDCS montages in eight healthy adults. Additionally, torque applied to a lever device during isometric wrist flexion and surface electromyography measurements of major muscle group activity in both arms were acquired concurrently with fNIRS. This multiparameter approach found that hemispheric suppression contralateral to wrist flexion changed resting-state connectivity from intra-hemispheric to inter-hemispheric and increased flexion speed (p < 0.05). Conversely, exciting this hemisphere increased opposing muscle output resulting in a decrease in speed but an increase in accuracy (p < 0.05 for both). The findings of this work suggest that tDCS with fNIRS and concurrent multimotor measurements can provide insights into how neuroplasticity changes muscle output, which could find future use in guiding motor rehabilitation.

Original languageEnglish
Article number116003
JournalJournal of Biomedical Optics
Issue number11
StatePublished - Nov 2013

Bibliographical note

Funding Information:
Support for this work was provided in part by the National Institute of Biomedical Imaging and Bioengineering (NIBIB), Grant No. 1R01EB013313-01 and by the Eunice Kennedy Shriver National Institute of Child Health and Human Development K23 grant, Grant No. 5K23HD050267.


  • cortical stimulation
  • functional near-infrared spectroscopy
  • motor cortex
  • neuroimaging
  • task performance
  • transcranial direct current stimulation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering


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