Electric field induced in a spherical volume conductor from arbitrary coils: application to magnetic stimulation and MEG

1992 ◽  
Vol 30 (4) ◽  
pp. 433-440 ◽  
Author(s):  
H. Eaton
Keyword(s):  
Electric Field ◽  
Magnetic Stimulation ◽  
Volume Conductor ◽  
Spherical Volume

scholarly journals Proof of concept study to develop a novel connectivity-based electric-field modelling approach for individualized targeting of transcranial magnetic stimulation treatment

2021 ◽  
Author(s):  
Nicholas L. Balderston ◽  
Joanne C. Beer ◽  
Darsol Seok ◽  
Walid Makhoul ◽  
Zhi-De Deng ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Electric Field ◽  
Magnetic Stimulation ◽  
Depression Symptoms ◽  
Single Subject ◽  
Proof Of Concept ◽  
Concept Study ◽  
Field Modelling ◽  
Left Dlpfc ◽  
Modelling Approach

AbstractResting state functional connectivity (rsFC) offers promise for individualizing stimulation targets for transcranial magnetic stimulation (TMS) treatments. However, current targeting approaches do not account for non-focal TMS effects or large-scale connectivity patterns. To overcome these limitations, we propose a novel targeting optimization approach that combines whole-brain rsFC and electric-field (e-field) modelling to identify single-subject, symptom-specific TMS targets. In this proof of concept study, we recruited 91 anxious misery (AM) patients and 25 controls. We measured depression symptoms (MADRS/HAMD) and recorded rsFC. We used a PCA regression to predict symptoms from rsFC and estimate the parameter vector, for input into our e-field augmented model. We modeled 17 left dlPFC and 7 M1 sites using 24 equally spaced coil orientations. We computed single-subject predicted ΔMADRS/HAMD scores for each site/orientation using the e-field augmented model, which comprises a linear combination of the following elementwise products (1) the estimated connectivity/symptom coefficients, (2) a vectorized e-field model for site/orientation, (3) rsFC matrix, scaled by a proportionality constant. In AM patients, our connectivity-based model predicted a significant decrease depression for sites near BA9, but not M1 for coil orientations perpendicular to the cortical gyrus. In control subjects, no site/orientation combination showed a significant predicted change. These results corroborate previous work suggesting the efficacy of left dlPFC stimulation for depression treatment, and predict better outcomes with individualized targeting. They also suggest that our novel connectivity-based e-field modelling approach may effectively identify potential TMS treatment responders and individualize TMS targeting to maximize the therapeutic impact.

A 4 × 4 array multichannel magnetic stimulation system using submillimeter sized planar square spiral coils: The spatial distribution of electromagnetic field

2022 ◽  
pp. 1-18
Author(s):  
Lei Tian ◽  
Limei Song ◽  
Yu Zheng ◽  
Jinhai Wang
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Spatial Distribution ◽  
Field Strength ◽  
Electric Field ◽  
Magnetic Stimulation ◽  
Spiral Coil ◽  
Average Magnetic Field ◽  
Stimulation System ◽  
Field Strengths

Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices.

scholarly journals A generalized workflow for conducting electric field–optimized, fMRI-guided, transcranial magnetic stimulation

2020 ◽  
Vol 15 (11) ◽  
pp. 3595-3614 ◽  
Author(s):  
Nicholas L. Balderston ◽  
Camille Roberts ◽  
Emily M. Beydler ◽  
Zhi-De Deng ◽  
Thomas Radman ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Electric Field ◽  
Magnetic Stimulation
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