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ORIGINAL RESEARCH article
Front. Neurosci.
Sec. Neuroprosthetics
Volume 18 - 2024 |
doi: 10.3389/fnins.2024.1425527
This article is part of the Research Topic Individual Neurodynamics Tunes personalized Neuromodulation
[INTuNe] View all 4 articles
Beta tACS of varying intensities differentially affect resting-state and movement-related M1-M1 connectivity
Provisionally accepted- 1 Murdoch University, Perth, Australia
- 2 Curtin University, Perth, Western Australia, Australia
Due to the interconnected nature of the brain, changes in one region are likely to affect other structurally and functionally connected regions. Emerging evidence indicates that single-site transcranial alternating current stimulation (tACS) can modulate functional connectivity between stimulated and interconnected unstimulated brain regions. However, our understanding of the network response to tACS is incomplete. Here, we investigated the effect of beta tACS of different intensities on phase-based connectivity between the left and right primary motor cortices in 21 healthy young adults (13 female; mean age 24.30 ± 4.84 years). Participants underwent four sessions of 20 minutes of 20 Hz tACS of varying intensities (sham, 0.5 mA, 1.0 mA, or 1.5 mA) applied to the left primary motor cortex at rest. We recorded resting-state and event-related electroencephalography (EEG) before and after tACS, analyzing changes in sensorimotor beta (13 -30 Hz) imaginary coherence (ImCoh), an index of functional connectivity. Event-related EEG captured movementrelated beta activity as participants performed self-paced button presses using their right index finger. For resting-state connectivity, we observed intensity-dependent changes in beta ImCoh: sham and 0.5 mA stimulation resulted in an increase in beta ImCoh, while 1.0 mA and 1.5 mA stimulation decreased beta ImCoh. For event-related connectivity, 1.5 mA stimulation decreased broadband ImCoh (4 -90 Hz) during movement execution. None of the other stimulation intensities significantly modulated event-related ImCoh during movement preparation, execution, or termination. Interestingly, changes in ImCoh during movement preparation following 1.0 mA and 1.5 mA stimulation were significantly associated with participants' pre-tACS peak beta frequency, suggesting that the alignment of stimulation frequency and peak beta frequency affected the extent of neuromodulation. Collectively, these results suggest that beta tACS applied to a single site influences connectivity within the motor network in a manner that depends on the intensity and frequency of stimulation. These findings have significant implications for both research and clinical applications.
Keywords: transcranial alternating current stimulation, Electroencephalography, Neural oscillations, Beta Oscillations, Motor Cortex, motor control, connectivity
Received: 29 Apr 2024; Accepted: 29 Aug 2024.
Copyright: © 2024 Wansbrough, Marinovic, Fujiyama and Vallence. 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) or licensor 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:
Kym Wansbrough, Murdoch University, Perth, Australia
Ann-Maree Vallence, Murdoch University, Perth, Australia
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