New paper: tDCS and Perception of Visual Vertical
Polarity-Dependent Misperception of Subjective Visual Vertical during and after Transcranial Direct Current Stimulation (tDCS)
PLoS ONE 11(3): e0152331. doi:10.1371/journal.pone.0152331
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Taiza E. G. Santos-Pontelli 1*, Brunna P. Rimoli 1, Diandra B. Favoretto 1, Suleimy C. Mazin 1, Dennis Q. Truong 2, Joao P. Leite 1, Octavio M. Pontes-Neto 1, Suzanne R. Babyar 3, Michael Reding 3, Marom Bikson 2, Dylan J. Edwards 3
1 Department of Neuroscience and Behavioral Sciences, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil, 2 Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of New York of the City University of New York, New York, New York, United States of America, 3 Non-invasive Brain Stimulation and Human Motor Control Laboratory, Burke Medical Research Institute, White Plains, New York, United States of America; Neurology Department, Weill Medical College, Cornell University, New York, New York, United States of America
Abstract: Pathologic tilt of subjective visual vertical (SVV) frequently has adverse functional conse- quences for patients with stroke and vestibular disorders. Repetitive transcranial magnetic stimulation (rTMS) of the supramarginal gyrus can produce a transitory tilt on SVV in healthy subjects. However, the effect of transcranial direct current stimulation (tDCS) on SVV has never been systematically studied. We investigated whether bilateral tDCS over the tempo- ral-parietal region could result in both online and offline SVV misperception in healthy sub- jects. In a randomized, sham-controlled, single-blind crossover pilot study, thirteen healthy subjects performed tests of SVV before, during and after the tDCS applied over the tempo- ral-parietal region in three conditions used on different days: right anode/left cathode; right cathode/left anode; and sham. Subjects were blind to the tDCS conditions. Montage-spe- cific current flow patterns were investigated using computational models. SVV was signifi- cantly displaced towards the anode during both active stimulation conditions when compared to sham condition. Immediately after both active conditions, there were rebound effects. Longer lasting after-effects towards the anode occurred only in the right cathode/left anode condition. Current flow models predicted the stimulation of temporal-parietal regions under the electrodes and deep clusters in the posterior limb of the internal capsule. The present findings indicate that tDCS over the temporal-parietal region can significantly alter human SVV perception. This tDCS approach may be a potential clinical tool for the treat- ment of SVV misperception in neurological patients.
