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Journal of Biomedical Optics • Open Access

Functional near-infrared spectroscopy maps cortical plasticity underlying altered motor performance induced by transcranial direct current stimulation
Author(s): Bilal Khan; Timea Hodics; Nathan Hervey; George V. Kondraske; Ann M. Stowe; George Alexandrakis

Paper Abstract

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.

Paper Details

Date Published: 5 November 2013
PDF: 12 pages
J. Biomed. Opt. 18(11) 116003 doi: 10.1117/1.JBO.18.11.116003
Published in: Journal of Biomedical Optics Volume 18, Issue 11
Show Author Affiliations
Bilal Khan, The Univ. of Texas at Arlington (United States)
Timea Hodics, The Univ. of Texas Southwestern Medical Ctr. at Dallas (United States)
Nathan Hervey, The Univ. of Texas at Arlington (United States)
George V. Kondraske, The Univ. of Texas at Arlington (United States)
Ann M. Stowe, The Univ. of Texas Southwestern Medical Ctr. at Dallas (United States)
George Alexandrakis, The Univ. of Texas at Arlington (United States)

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