Manipulation of Human Verticality Using High-Definition Transcranial Direct Current Stimulation

Using conventional tDCS over the temporo-parietal junction (TPJ) we previously reported that it is possible to manipulate subjective visual vertical (SVV) and postural control. We also demonstrated that high-definition tDCS (HD-tDCS) can achieve substantially greater cortical stimulation focality th...

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Published in:	Frontiers in neurology Vol. 9; p. 825
Main Authors:	Santos, Taiza E G, Favoretto, Diandra B, Toostani, Iman Ghodratti, Nascimento, Diego C, Rimoli, Brunna P, Bergonzoni, Eduardo, Lemos, Tenysson Will, Truong, Dennis Q, Delbem, Alexandre C B, Makkiabadi, Bahador, Moraes, Renato, Louzada, Francisco, Bikson, Marom, Leite, Joao P, Edwards, Dylan J
Format:	Journal Article
Language:	English
Published:	Switzerland Frontiers Media S.A 22-10-2018
Subjects:	electroencephalography high-definition transcranial direct current stimulation Neurology postural control temporo-parietal junction verticality electroencephalography postural control high-definition transcranial direct current stimulation verticality temporo-parietal junction
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Summary:	Using conventional tDCS over the temporo-parietal junction (TPJ) we previously reported that it is possible to manipulate subjective visual vertical (SVV) and postural control. We also demonstrated that high-definition tDCS (HD-tDCS) can achieve substantially greater cortical stimulation focality than conventional tDCS. However, it is critical to establish dose-response effects using well-defined protocols with relevance to clinically meaningful applications. To conduct three pilot studies investigating polarity and intensity-dependent effects of HD-tDCS over the right TPJ on behavioral and physiological outcome measures in healthy subjects. We additionally aimed to establish the feasibility, safety, and tolerability of this stimulation protocol. We designed three separate randomized, double-blind, crossover phase I clinical trials in different cohorts of healthy adults using the same stimulation protocol. The primary outcome measure for trial 1 was SVV; trial 2, weight-bearing asymmetry (WBA); and trial 3, electroencephalography power spectral density (EEG-PSD). The HD-tDCS montage comprised a single central, and 3 surround electrodes (HD-tDCS3x1) over the right TPJ. For each study, we tested 3x2 min HD-tDCS3x1 at 1, 2 and 3 mA; with anode center, cathode center, or sham stimulation, in random order across days. We found significant SVV deviation relative to baseline, specific to the cathode center condition, with consistent direction and increasing with stimulation intensity. We further showed significant WBA with direction governed by stimulation polarity (cathode center, left asymmetry; anode center, right asymmetry). EEG-PSD in the gamma band was significantly increased at 3 mA under the cathode. The present series of studies provide converging evidence for focal neuromodulation that can modify physiology and have behavioral consequences with clinical potential.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Reviewed by: Christopher Bockisch, Universität Zürich, Switzerland; Paul Taylor, Ludwig Maximilian University Neurology, Germany This article was submitted to Neuro-Otology, a section of the journal Frontiers in Neurology Edited by: Dominik Straumann, Universität Zürich, Switzerland
ISSN:	1664-2295 1664-2295
DOI:	10.3389/fneur.2018.00825