EEG modulation by tDCS montages

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EEG modulation by different transcranial direct current stimulation (tDCS) montages: a randomized double-blind sham-control mechanistic pilot trial in healthy participants.

Background: Based on our Phantom study on transcranial direct current stimulation (tDCS), we hypothesized that EEG band power and field confinement would be greater following left dorsolateral prefrontal cortex (DLPFC – F3) tDCS using circular vs. rectangular electrodes. Methods: Double-blind randomized trial comparing tDCS with anode over the left DLPFC (groups: rectangular electrodes, circular electrodes, sham) and 2 active subgroup references (right shoulder vs. right DLPFC cathodes). Results: Twenty-four randomized participants were assessed. We indeed found higher average EEG power spectral density (PSD) across bands for circular vs. rectangular electrodes, largely confined to F3 and there was a significant increase at AF3 for low alpha (p=0.037). Significant differences included: increased PSD in low beta (p=0.024) and theta bands (p=0.021) at F3, and in theta (p=0.036) at FC5 for the right DLPFC vs. shoulder with no coherence changes. We also found PSD differences between active vs. sham tDCS at Fz for alpha (p=0.043), delta (p=0.036), high delta (p=0.030); and at FC1 for alpha (p=0.031), with coherence differences for F3-Fz in beta (p=0.044), theta (p=0.044), delta (p=0.037) and high delta (p=0.009). Conclusion: This pilot study despite having low statistical power given its small sample size shows that active left DLPFC tDCS modulates EEG frontocentrally and suggests that electrode shapes/reference locations affect its neurophysiological effects, such as increased low alpha power at AF3 using circular vs. rectangular electrodes. Further research with more participants is warranted.

PMID: 33305643 [PubMed – as supplied by publisher]

Expert Rev Med Devices. 2020 Dec 11;:

Authors: El-Hagrassy MM, Duarte D, Lu J, Uygur-Kucukseymen E, Munger M, Thibaut A, Lv P, Morales-Quezada L, Fregni F