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Front. Neurosci. | doi: 10.3389/fnins.2019.00286

Single Sessions of High-Definition Transcranial Direct Current Stimulation do not Alter Lower Extremity Biomechanical or Corticomotor Response Variables Post-Stroke

  • 1Health and Exercise Science, Medical University of South Carolina, United States
  • 2Ralph H. Johnson VA Medical Center, United States
  • 3High Point University, United States

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to modulate cortical activity. However, measured effects on clinically relevant assessments have been inconsistent, possibly due to the non-focal dispersion of current from traditional two electrode configurations. High-definition (HD)-tDCS uses a small array of electrodes (N = 5) to improve targeted current delivery. The purpose of this study was to determine the effects of a single session of anodal and cathodal HD-tDCS on gait kinematics and kinetics and the corticomotor response to transcranial magnetic stimulation (TMS) in individuals post-stroke. We hypothesized that ipsilesional anodal stimulation would increase the corticomotor response to TMS leading to beneficial changes in gait. Eighteen participants post-stroke (average age 64.8 years, SD 12.5; average months post-stroke 54, SD 42; average lower extremity Fugl-Meyer score 26, SD 6) underwent biomechanical and corticomotor response testing on three separate occasions prior to and after HD-tDCS stimulation. In a randomized order, anodal, cathodal, and sham HD-tDCS were applied to the ipsilesional motor cortex for 20 minutes while participants pedaled on a recumbent cycle ergometer. Gait kinetic and kinematic data were collected while walking on an instrumented split-belt treadmill with motion capture. The corticomotor response of the paretic and non-paretic tibialis anterior muscles were measured using neuronavigated TMS. Repeated measures ANOVAs using within-subject factors of time point (pre, post) and stimulation type (sham, anodal, cathodal) were used to compare effects of HD-tDCS stimulation on measured variables. HD-tDCS had no effect on over ground walking speed (P > 0.41), or kinematic variables (P > 0.54). The corticomotor responses of the tibialis anterior muscles were also unaffected by HD-tDCS (resting motor threshold, P = 0.15; motor evoked potential amplitude, P = 0.25; motor evoked potential normalized latency, P = 0.66). A single session of anodal or cathodal HD-tDCS delivered to a standardized ipsilesional area of the motor cortex does not appear to alter gait kinematics or corticomotor response post-stroke. Repeated sessions and individualized delivery of HD-tDCS may be required to induce beneficial plastic effects. Contralesional stimulation should also be investigated due to the altered interactions between the cerebral hemispheres post-stroke.

Keywords: HD-tDCS, Anodal, Cathodal, Gait, mobility, tDCS, Brain Stimulation, TMS

Received: 05 Sep 2018; Accepted: 11 Mar 2019.

Edited by:

Ioan Opris, University of Miami, United States

Reviewed by:

Winston D. Byblow, The University of Auckland, New Zealand
Antonio Oliviero, Fundación del Hospital Nacional de Parapléjicos, Spain  

Copyright: © 2019 Kindred, Kautz, Wonsetler and Bowden. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Mark G. Bowden, Medical University of South Carolina, Health and Exercise Science, Charleston, Co, United States,