Numerical Analyses of Transcranial Magnetic Stimulation Based on Individual Brain Models by Using a Scalar-Potential Finite-Difference Method

Yamamoto, Ken; Takiyama, Yoshihiro; Saitoh, Youichi; Sekino, Masaki

doi:10.1109/tmag.2016.2519443

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…Different brain tissue layers were not differentiated so that the model possessed an isotropic inner electrical conductivity of 0.33 S/m, and the cortical surface was assumed to be at a depth of 1.5 cm from the surface of the model. To calculate the electric field induced by high-frequency oscillating currents in the coils, a scalar-potential finite-difference (SPFD) tool developed by our group was employed (Yamamoto et al, 2016 ). The electric field produced inside the brain model can be acquired by solving the following equation:…”

Section: Methodsmentioning

confidence: 99%

Magnetically Induced Temporal Interference for Focal and Deep-Brain Stimulation

Xin

Kuwahata

Liu

et al. 2021

Front. Hum. Neurosci.

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Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that has been clinically applied for neural modulation. Conventional TMS systems are restricted by the trade-off between depth penetration and the focality of the induced electric field. In this study, we integrated the concept of temporal interference (TI) stimulation, which has been demonstrated as a non-invasive deep-brain stimulation method, with magnetic stimulation in a four-coil configuration. The attenuation depth and spread of the electric field were obtained by performing numerical simulation. Consequently, the proposed temporally interfered magnetic stimulation scheme was demonstrated to be capable of stimulating deeper regions of the brain model while maintaining a relatively narrow spread of the electric field, in comparison to conventional TMS systems. These results demonstrate that TI magnetic stimulation could be a potential candidate to recruit brain regions underneath the cortex. Additionally, by controlling the geometry of the coil array, an analogous relationship between the field depth and focality was observed, in the case of the newly proposed method. The major limitations of the methods, however, would be the considerable intensity and frequency of the input current, followed by the frustration in the thermal management of the hardware.

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Section: Methodsmentioning

confidence: 99%

Magnetically Induced Temporal Interference for Focal and Deep-Brain Stimulation

Xin

Kuwahata

Liu

et al. 2021

Front. Hum. Neurosci.

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“…To assess the extent of the brain areas stimulated under different stimulation conditions, we simulated the TMS-induced eddy current density in the brain model of the Japanese monkey by the scalar potential finite difference (SPFD) method (10,11). As shown in Fig.…”

Section: Simulation Of Tms-induced Eddy Current Density In the Monkey Brainmentioning

confidence: 99%

“…The extent of TMS-induced eddy currents in the monkey brain was assessed by the SPFD method (Fig. 1C) (10,11). We used the monkey brain model (the MRI standard brain of Japanese macaque monkey, http://brainatlas.brain.riken.jp/jm/modules/xoonips/listitem.php?index_id=9) (63) segmented into three materials (white matter, gray matter, and cerebrospinal fluid) and calculated the density of eddy currents induced by TMS with the intensity of 60% of the machine power.…”

Section: Simulation Of Tms-induced Eddy Current Density In Monkey Brainmentioning

confidence: 99%

Depression-like state induced by low-frequency repetitive transcranial magnetic stimulation to ventral medial frontal cortex in monkeys

Nakamura

Kishimoto

Sekino

et al. 2021

Preprint

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The medial frontal cortex (MFC), especially its ventral part, has long been of great interest with respect to the pathology of mood disorders. A number of human brain imaging studies have demonstrated the abnormalities of this brain region in patients with mood disorders, however, whether it is critically involved in the pathogenesis of such disorders remains to be fully elucidated. In this study, we conducted a causal study to investigate how the suppression of neural activity in the ventral region of the MFC (vMFC) affects the behavioral and physiological states of monkeys by using repetitive transcranial magnetic stimulation (rTMS). By using low-frequency rTMS (LF-rTMS) as an inhibitory intervention, we found that LF-rTMS targeting the vMFC induced a depression-like state in monkeys, which was characterized by a reduced spontaneous behavioral activity, increased plasma cortisol level, impaired sociability, and decreased motivation level. On the other hand, no such significant changes in behavioral and physiological states were observed when targeting the other MFC regions, dorsal or posterior. We further found that the administration of an antidepressant agent, ketamine, ameliorated the abnormal behavioral and physiological states induced by the LF-rTMS intervention. These findings indicate the causal involvement of the vMFC in the regulation of mood and affect and the validity of the LF-rTMS-induced dysfunction of the vMFC as a nonhuman primate model of the depression-like state.

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“…The EF strengths on the target region had a normalised standard deviation of 18% (mean value of 203 V/m). In summary, various studies have investigated inter-subject variability of the induced EF ranging from a few to up to 50 subjects (Bijsterbosch et al, 2012;Crowther, Hadimani and Jiles, 2014;Lee et al, 2016;Yamamoto et al, 2016). In the studies reviewed in this and other subsections, adults have been the predominant population segment (figure 5(b)), and the elderly and youth populations are almost unexplored.…”

Section: Effects Of Anatomical and Inter-individual Factorsmentioning

confidence: 99%

“…Hernandez-Garcia et al 2010Homogeneous sphere (7.5 cm) Peterchev (2013, 2014) Homogeneous sphere (8.5 cm) Nummenmaa et al (2013) Homogeneous sphere (globally best-fitted to inner-skull surface) Homogeneous sphere (locally fitted to inner-skull surface close to TMS coil location) Koponen, Nieminen and Ilmoniemi (2015) Homogeneous sphere (8.5 cm) Yamamoto et al (2016) Homogeneous sphere (7.5 cm)…”

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confidence: 99%

Review on biophysical modelling and simulation studies for transcranial magnetic stimulation

2020

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Transcranial magnetic stimulation (TMS) is a technique for noninvasively stimulating a brain area for therapeutic, rehabilitation treatments and neuroscience research. Despite our understanding of the physical principles and experimental developments pertaining to TMS, it is difficult to identify the exact brain target as the generated dosage exhibits a non-uniform distribution owing to the complicated and subject-dependent brain anatomy and the lack of biomarkers that can quantify the effects of TMS in most cortical areas. Computational dosimetry has progressed significantly and enables TMS assessment by computation of the induced electric field (the primary physical agent known to activate the brain neurons) in a digital representation of the human head. In this review, TMS dosimetry studies are summarised, clarifying the importance of the anatomical and human biophysical parameters and computational methods. This review shows that there is a high consensus on the importance of a detailed cortical folding representation and an accurate modelling of the surrounding cerebrospinal fluid. Recent studies have also enabled the prediction of individually optimised stimulation based on magnetic resonance imaging of the patient/subject and have attempted to understand the temporal effects of TMS at the cellular level by incorporating neural modelling. These efforts, together with the fast deployment of personalised TMS computations, will permit the adoption of TMS dosimetry as a standard procedure in clinical procedures.

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Numerical Analyses of Transcranial Magnetic Stimulation Based on Individual Brain Models by Using a Scalar-Potential Finite-Difference Method

Cited by 11 publications

References 7 publications

Magnetically Induced Temporal Interference for Focal and Deep-Brain Stimulation

Magnetically Induced Temporal Interference for Focal and Deep-Brain Stimulation

Depression-like state induced by low-frequency repetitive transcranial magnetic stimulation to ventral medial frontal cortex in monkeys

Review on biophysical modelling and simulation studies for transcranial magnetic stimulation

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