Triple tSMS system (“SHIN jiba”) for non-invasive deep brain stimulation: a validation study in healthy subjects

Abstract

Background Transcranial static magnetic field stimulation (tSMS) using a small and strong neodymium (NdFeB) magnet can temporarily suppress brain functions below the magnet. It is a promising non-invasive brain stimulation modality because of its competitive advantages such as safety, simplicity, and low-cost. However, current tSMS is insufficient to effectively stimulate deep brain areas due to attenuation of the magnetic field with the distance from the magnet. The aim of this study was to develop a brand-new tSMS system for non-invasive deep brain stimulation. Methods We designed and fabricated a triple tSMS system with three cylindrical NdFeB magnets placed close to each other. We compared the strength of magnetic field produced by the triple tSMS system with that by the current tSMS. Furthermore, to confirm its function, we stimulated the primary motor area in 17 healthy subjects with the triple tSMS for 20 min and assessed the cortical excitability using the motor evoked potential (MEP) obtained by transcranial magnetic stimulation. Results Our triple tSMS system produced the magnetic field sufficient for neuromodulation up to 80 mm depth from the magnet surface, which was 30 mm deeper than the current tSMS system. In the stimulation experiment, the triple tSMS significantly reduced the MEP amplitude, demonstrating a successful inhibition of the M1 excitability in healthy subjects. Conclusion Our triple tSMS system has an ability to produce an effective magnetic field in deep areas and to modulate the brain functions. It can be used for non-invasive deep brain stimulation.

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

“…CH3 might not receive sufficient magnetic force as the centers of the magnets were surrounded by CH36, CH37, CH40, and CH41, as depicted in Figure 1 . Further, a previous study demonstrated that although the triple tSMS system could provide the same neuromodulatory effect as the conventional tSMS, the magnetic field just below the triple tSMS system was weaker than the conventional tSMS, due to the interference of the magnetic fields produced by the three magnets ( Shibata et al, 2022 ). Since CH40 was positioned just at the boundary of two magnets, its activity may not have been suppressed due to interference of the magnetic fields, which will be a topic for future investigation.…”

“…We used a triple tSMS system with three cylindrical nickel-plated (Ni–Cu–Ni) NdFeB magnets placed close to one another ( Shibata et al, 2022 ):…”

“…The study used three magnets to resolve a trade-off between the summation of the magnetic fields from multiple magnets and the avoidance of poor focality. The triple tSMS system can produce an effective magnetic field in deep areas and modulate brain functions ( Shibata et al, 2022 ). The current tSMS system with a single magnet system was insufficient to effectively stimulate deep brain areas due to the attenuation of the magnetic field proportionally to the distance from the magnet.…”

“…The current tSMS system with a single magnet system was insufficient to effectively stimulate deep brain areas due to the attenuation of the magnetic field proportionally to the distance from the magnet. In contrast, the triple tSMS system produced a magnetic field sufficient for neuromodulation up to 80 mm depth from the magnet surface, 30 mm deeper than the conventional tSMS system ( Shibata et al, 2022 ). The triple tSMS is as safe as the conventional tSMS with a single magnet system.…”

Effect of transcranial static magnetic stimulation over unilateral or bilateral motor association cortex on performance of simple and choice reaction time tasks

“…In the past decade, various local brain regions such as the sensorimotor ( Silbert et al, 2013 ; Kirimoto et al, 2014 , 2016 , 2018 ; Nojima et al, 2015 , 2019 ; Davila-Perez et al, 2019 ; Nakagawa et al, 2019 ; Shibata et al, 2020 ), supplementary motor ( Kirimoto et al, 2016 ; Pineda-Pardo et al, 2019 ; Tsuru et al, 2020 ; Guida et al, 2023 ), visual ( Gonzalez-Rosa et al, 2015 ; Oliviero et al, 2015 ; Lozano-Soto et al, 2018 ), and dorsolateral prefrontal ( Sheffield et al, 2019 ; Chen et al, 2021 ; Watanabe et al, 2021 , 2023 ; Soto-León et al, 2023 ) cortices have been revealed to be modulated by tSMS, with potential clinical applications for neurological disorders ( Di Lazzaro et al, 2021 ; Dileone et al, 2022 ; Shimomura et al, 2023 ). In addition, a new tSMS device constructed with three NdFeB magnets (called “SHIN jiba”) was introduced last year, and simulation has revealed that this triple tSMS can produce the greater static magnetic fields than the conventional tSMS ( Shibata et al, 2022 ). However, its effect on behavioral performance has not been clear to date.…”