scholarly journals A Computational Modeling Study to Investigate the Use of Epicranial Electrodes to Deliver Interferential Stimulation to Subcortical Regions

2021 ◽  
Vol 15 ◽  
Author(s):  
Ahmad Khatoun ◽  
Boateng Asamoah ◽  
Myles Mc Laughlin
Keyword(s):  
Electric Field ◽  
Computational Modeling ◽  
Electric Fields ◽  
Electric Stimulation ◽  
Cortical Stimulation ◽  
Tetrahedral Mesh ◽  
Subcortical Region ◽  
Subcortical Stimulation ◽  
Transcranial Electric Stimulation ◽  
Subcortical Regions

Background: Epicranial cortical stimulation (ECS) is a minimally invasive neuromodulation technique that works by passing electric current between subcutaneous electrodes positioned on the skull. ECS causes a stronger and more focused electric field in the cortex compared to transcranial electric stimulation (TES) where the electrodes are placed on the scalp. However, it is unknown if ECS can target deeper regions where the electric fields become relatively weak and broad. Recently, interferential stimulation (IF) using scalp electrodes has been proposed as a novel technique to target subcortical regions. During IF, two high, but slightly different, frequencies are applied which sum to generate a low frequency field (i.e., 10 Hz) at a target subcortical region. We hypothesized that IF using ECS electrodes would cause stronger and more focused subcortical stimulation than that using TES electrodes.Objective: Use computational modeling to determine if interferential stimulation-epicranial cortical stimulation (IF-ECS) can target subcortical regions. Then, compare the focality and field strength of IF-ECS to that of interferential Stimulation-transcranial electric stimulation (IF-TES) in the same subcortical region.Methods: A human head computational model was developed with 19 TES and 19 ECS disk electrodes positioned on a 10–20 system. After tetrahedral mesh generation the model was imported to COMSOL where the electric field distribution was calculated for each electrode separately. Then in MATLAB, subcortical targets were defined and the optimal configurations were calculated for both the TES and ECS electrodes.Results: Interferential stimulation using ECS electrodes can deliver stronger and more focused electric fields to subcortical regions than IF using TES electrodes.Conclusion: Interferential stimulation combined with ECS is a promising approach for delivering subcortical stimulation without the need for a craniotomy.

scholarly journals Spatiotemporal structure of intracranial electric fields induced by transcranial electric stimulation in human and nonhuman primates

2016 ◽  
Author(s):  
Alexander Opitz ◽  
Arnaud Falchier ◽  
Chao-Gan Yan ◽  
Erin Yeagle ◽  
Gary Linn ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electric Stimulation ◽  
Brain Regions ◽  
Electrode Arrays ◽  
Non Invasive ◽  
Crucial Information ◽  
Cebus Monkeys ◽  
Transcranial Electric Stimulation ◽  
The Brain

AbstractTranscranial electric stimulation (TES) is an emerging technique, developed to non-invasively modulate brain function. However, the spatiotemporal distribution of the intracranial electric fields induced by TES remains poorly understood. In particular, it is unclear how much current actually reaches the brain, and how it distributes across the brain. Lack of this basic information precludes a firm mechanistic understanding of TES effects. In this study we directly measure the spatial and temporal characteristics of the electric field generated by TES using stereotactic EEG (s-EEG) electrode arrays implanted in cebus monkeys and surgical epilepsy patients. We found a small frequency dependent decrease (10%) in magnitudes of TES induced potentials and negligible phase shifts over space. Electric field strengths were strongest in superficial brain regions with maximum values of about 0.5 mV/mm. Our results provide crucial information for the interpretation of human TES studies and the optimization and design of TES stimulation protocols. In addition, our findings have broad implications concerning electric field propagation in non-invasive recording techniques such as EEG/MEG.

scholarly journals Electric field dynamics in the brain during multi-electrode transcranial electric stimulation

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ivan Alekseichuk ◽  
Arnaud Y. Falchier ◽  
Gary Linn ◽  
Ting Xu ◽  
Michael P. Milham ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Stimulation ◽  
Transcranial Electric Stimulation ◽  
The Brain

scholarly journals Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

2017 ◽  
Vol 10 (4) ◽  
pp. e25-e26 ◽  
Author(s):  
Yu Huang ◽  
Anli Liu ◽  
Belen Lafon ◽  
Daniel Friedman ◽  
Michael Dayan ◽  
...  
Keyword(s):  
Human Brain ◽  
Electric Fields ◽  
Electric Stimulation ◽  
Transcranial Electric Stimulation

scholarly journals Comparative Modeling of Transcranial Magnetic and Electric Stimulation in Mouse, Monkey, and Human

2018 ◽  
Author(s):  
Ivan Alekseichuk ◽  
Kathleen Mantell ◽  
Sina Shirinpour ◽  
Alexander Opitz
Keyword(s):  
Finite Element ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Mouse Brain ◽  
Electric Stimulation ◽  
Human Model ◽  
Brain Anatomy ◽  
List Type

ABSTRACTTranscranial magnetic stimulation (TMS) and transcranial electric stimulation (TES) are increasingly popular methods to noninvasively affect brain activity. However, their mechanism of action and dose-response characteristics remain under active investigation. Translational studies in animals play a pivotal role in these efforts due to a larger neuroscientific toolset enabled by invasive recordings. In order to translate knowledge gained in animal studies to humans, it is crucial to generate comparable stimulation conditions with respect to the induced electric field in the brain. Here, we conduct a finite element method (FEM) modeling study of TMS and TES electric fields in a mouse, capuchin monkey, and human model. We systematically evaluate the induced electric fields and analyze their relationship to head and brain anatomy. We find that with increasing head size, TMS-induced electric field strength first increases and then decreases according to a two-term exponential function. TES-induced electric field strength strongly decreases from smaller to larger specimen with up to 100x fold differences across species. Our results can serve as a basis to compare and match stimulation parameters across studies in animals and humans.HIGHLIGHTSTranslational research in brain stimulation should account for large differences in induced electric fields in different organismsWe simulate TMS and TES electric fields using anatomically realistic finite element models in three species: mouse, monkey, and humanTMS with a 70 mm figure-8 coil creates an approximately 2-times weaker electric field in a mouse brain than in monkey and human brains, where electric field strength is comparableTwo-electrode TES creates an approximately 100-times stronger electric field in a mouse brain and 3.5-times stronger electric field in a monkey brain than in a human brain

P097 Direct measurement of electric fields in human and monkeys during transcranial electric stimulation

2017 ◽  
Vol 128 (3) ◽  
pp. e57-e59
Author(s):  
A. Opitz ◽  
A. Falchier ◽  
C.-G. Yan ◽  
E. Yeagle ◽  
G. Linn ◽  
...  
Keyword(s):  
Electric Fields ◽  
Direct Measurement ◽  
Electric Stimulation ◽  
Transcranial Electric Stimulation

scholarly journals Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Yu Huang ◽  
Anli A Liu ◽  
Belen Lafon ◽  
Daniel Friedman ◽  
Michael Dayan ◽  
...  
Keyword(s):  
Human Brain ◽  
Electric Fields ◽  
Electric Stimulation ◽  
Animal Studies ◽  
Current Flow ◽  
Electrical Currents ◽  
Tissue Conductivity ◽  
Flow Models ◽  
Transcranial Electric Stimulation

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.

scholarly journals Effects of electrodes length and insulation for transcranial electric stimulation

2019 ◽  
Vol 10 ◽  
pp. 111
Author(s):  
Ryosuke Tomio
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Subcutaneous Fat ◽  
Motor Evoked Potential ◽  
Threshold Level ◽  
Lower Threshold ◽  
The Finite Element Method ◽  
Stimulation Threshold ◽  
Transcranial Electric Stimulation ◽  
The Brain

Background: The aim of this study is to investigate the effects of length and insulation of the corkscrew electrodes for transcranial motor evoked potential (tMEP) monitoring. Methods: We used the finite element method to visualize the electric field in the brain, which was generated by electrodes of different lengths (4, 7, and 12 mm). Two types of head models were generated: A model that included a subcutaneous fat layer and another without a fat layer. Two insulated needle types of conductive tip (5 and 2 mm) were studied. The stimulation threshold levels of hand tMEP were measured in a clinical setting to compare normal corkscrew and insulated 7-mm depth corkscrew. Results: The electric field in the brain depended on the electrode depths in the no fat layer model. The deeper the electrodes reached, the stronger the electric fields generated. Electrode insulation made a difference in the fat layer models. The threshold level recordings of tMEP revealed that the 7-mm insulated electrodes showed a lower threshold than the normal electrodes by one-side replacement in each patient: 33.6 ± 9.6 mA and 36.3 ± 11.0 mA (n =16, P < 0.001), respectively. The 7-mm insulated electrodes also showed a lower threshold than the normal electrodes when both sides, electrodes were replaced: 34.4 ± 8.6 mA and 37.5 ± 9.2 mA (n =10, P = 0.003), respectively. Conclusions: The electrodes depth reached enough to skull is considered to be efficient. Insulation of the electrodes with a conductive tip is efficient when there is subcutaneous fat layer.

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