Schedule of Events | Symposia

HD-tDCS of the left primary motor cortices upregulates alpha power in the motor circuitry during eyes-closed rest

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Yasra Arif¹ (yasra027@gmail.com), Maggie Rempe², Nathan Petro³, Hannah Okelberry⁴, Jason John⁵, Grant Garrison⁶, Kennedy Kress⁷, Kellen McDonald⁸, Giorgia Picci⁹, Tony Wilson¹⁰; ¹Institute for Human Neuroscience, Boys Town National Research Hospital

Noninvasive brain stimulation techniques, including transcranial direct current stimulation (tDCS), have been shown to modulate cortical excitability. While several electroencephalography (EEG) studies have targeted the primary motor cortices to manipulate motor circuitry, inter-individual baseline variability and volume conduction in conventional EEG studies complicate the accurate characterization of tDCS effects on spontaneous neural dynamics. In the current study, we used high-definition tDCS (HD-tDCS) combined with high-density magnetoencephalography (MEG) to overcome these limitations. Sixty-three healthy adults underwent three stimulation visits (i.e., anodal, cathodal, and sham), during which they completed 20 min of 4X1 motor HD-tDCS followed by eyes-closed resting state during MEG. MEG data were source-imaged and whole-brain vertex-wise ANOVAs were conducted on spatially resolved relative power maps to assess stimulation-related differences in the spontaneous neural power across six canonical frequency bands. Our neural findings indicated that both anodal and cathodal HD-tDCS were associated with significantly increased relative alpha power in distributed brain regions, including bilateral posterior superior temporal cortices, paracentral lobules, right inferior parietal regions, right somatosensory cortices, and left parieto-occipital cortices compared to sham. Surprisingly, no polarity-specific effects were observed. Broadly our data align with previous studies documenting both local and widespread effects of tDCS. Further, the observed spontaneous alpha changes in the somatosensory and association cortices are indicative of downstream modulation of motor-related circuits. This highlights the potential of motor HD-tDCS to influence sensory integration and motor processing across the brain even in the absence of active movement, suggesting the need for further exploration in clinical populations.

Topic Area: PERCEPTION & ACTION: Motor control