Abstract
Transcranial static magnetic field stimulation (tSMS) is a non-invasive brain stimulation technique known to reduce cortical excitability. Although its effectiveness has been demonstrated in various cortical regions, it remains unclear whether somatosensory processing is influenced by this stimulation. The purpose of this study was to investigate whether tSMS over the primary somatosensory cortex (S1) modulates somatosensory evoked potentials (SEPs) and high-frequency oscillations superimposed on them (somatosensory HFOs). In a randomized crossover study, twenty healthy young adults received tSMS or sham stimulation over the left S1 (corresponding to C3 of the international 10–20 system) for 20 min. SEPs were recorded in response to right median nerve stimulation before, immediately after, and 20 min after stimulation. Somatosensory HFOs were extracted by applying a 400–800 Hz band-pass filter to SEP waveforms and separated into early and late components relative to the N20 peak latency. TSMS over the left S1 significantly reduced the amplitude of early HFOs 20 min after stimulation, whereas late HFOs remained unchanged. No effects of tSMS were observed on the N20 component of standard SEPs, which reflects neural activity in area 3b of the S1. Early and late HFOs are thought to reflect the action potentials of thalamocortical fibers and the activity of GABAergic interneurons, respectively. These findings therefore suggest that tSMS over the S1 selectively attenuates thalamocortical input while exerting no effect on GABAergic interneuron activity.
Data availability
The datasets used during the study will be available from the corresponding author on reasonable request.
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Acknowledgements
We thank all the participants who have devoted their time and effort to this study. This study was partially supported by grants from the Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research [grant number: 22K17777 and 24K14259]) and AUHW Grant-in-Aid for Encouragement of Early-Career Scientists (EECS2517).
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Yuki Tanaka collected and analyzed data and drafted the manuscript. Aoki Takahashi, Riku Ishizaka, Kodai Minami, Taisei Miyazaki, Kenta Oguma, and Nodoka Shimizume collected data. Isamu Ozaki conceptualized the study and revised the manuscript. Tatsunori Watanabe conceptualized, designed, and supervised the study and revised the manuscript.
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Tanaka, Y., Takahashi, A., Ishizaka, R. et al. Somatosensory evoked potentials and high-frequency oscillations after transcranial static magnetic stimulation over the primary somatosensory cortex. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38767-2
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DOI: https://doi.org/10.1038/s41598-026-38767-2