Effects of transcranial static magnetic stimulation over the primary motor cortex on local and network spontaneous electroencephalogram oscillations

Abstract

Transcranial static magnetic stimulation (tSMS) is a novel non-invasive brain stimulation technique that reduces cortical excitability at the stimulation site. We investigated the effects of tSMS over the left primary motor cortex (M1) for 20 min on the local electroencephalogram (EEG) power spectrum and interregional EEG coupling. Twelve right-handed healthy subjects participated in this crossover, double-blind, sham-controlled study. Resting-state EEG data were recorded for 3 min before the intervention and 17 min after the beginning of the intervention. The power spectrum at the left central electrode (C3) and the weighted phase lag index (wPLI) between C3 and the other electrodes was calculated for theta (4–8 Hz), alpha (8–12 Hz), and beta (12–30 Hz) frequencies. The tSMS significantly increased theta power at C3 and the functional coupling in the theta band between C3 and the parietal midline electrodes. The tSMS over the left M1 for 20 min exhibited modulatory effects on local cortical activity and interregional functional coupling in the theta band. The neural oscillations in the theta band may have an important role in the neurophysiological effects induced by tSMS over the frontal cortex.

Effects of transcranial static magnetic field stimulation over the left dorsolateral prefrontal cortex on random number generation

“…tSMS is based on the transcranial application of a static magnetic field (120-200 mT at 2-3 cm from the magnet surface) (Rivadulla et al, 2014) over the skull. Recently, a number of studies applying tSMS over different cortical areas (e.g., visual, motor, supplementary motor and somatosensory cortices) have demonstrated neurophysiological and/or behavioral effects in healthy subjects and patients (Arias et al, 2017;Carrasco-López et al, 2017;Dileone et al, 2018;Gonzalez-Rosa et al, 2015;Kirimoto et al, 2020Kirimoto et al, , 2018Kirimoto et al, , 2014Lacroix et al, 2019;Lozano-Soto et al, 2018;Nakagawa et al, 2019;Nakagawa and Nakazawa, 2018;Nojima et al, 2019Nojima et al, , 2016Oliviero et al, 2011;Sheffield et al, 2019;Shibata et al, 2021;Silbert et al, 2013;Soto-León et al, 2022). These studies support the main idea that tSMS has general inhibitory effects by a reduction in the neuronal excitability, and one of the proposed mechanisms for this to happen is a mechanical mechanism (Hernando et al, 2020).…”

Tackling social anxiety with targeted brain stimulation: investigating the effects of transcranial static magnetic field stimulation on self-focused attention

“…The fourth limitation is the need for more clarity regarding the remote brain effect. The researcher reported that tSMS can not only suppress brain function directly under the magnet but also induce various remote effects through brain networks ( Shibata et al, 2021 ; Takamatsu et al, 2021 ). However, this study only measured the rPFA cortex, and the impact of tSMS on this area that extends to other brain regions warrants further investigation.…”

Neurophysiological correlates of tactile width discrimination in humans

“…Theta band has been previously associated with tactile function, namely in roughness discrimination (Genna et al, 2017(Genna et al, , 2018. Alternatively, such theta modulation could also reflect some form of interaction between the somatosensory and the motor cortex (Shibata et al, 2021) as expected from the change occurring between the tactile discrimination period and the response period (more associated "Task description" the electrodes presenting modulations between the discrimination and response periods are presented. "Tactile discrimination" the networks of electrodes that are correlated with performance "between-subjects" and "within-subjects" are presented.…”