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

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Alexander Opitz ◽  
Arnaud Falchier ◽  
Chao-Gan Yan ◽  
Erin M. Yeagle ◽  
Gary S. Linn ◽  
...  
Keyword(s):  
Electric Fields ◽  
Electric Stimulation ◽  
Nonhuman Primates ◽  
Spatiotemporal Structure ◽  
Transcranial Electric Stimulation

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

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 Simulating individually targeted transcranial electric stimulation for experimental application

2019 ◽  
Author(s):  
Jan-Ole Radecke ◽  
Asad Khan ◽  
Andreas K. Engel ◽  
Carsten H. Wolters ◽  
Till R. Schneider
Keyword(s):  
Electric Fields ◽  
Electric Stimulation ◽  
Target Location ◽  
Complex Interaction ◽  
Spatial Extent ◽  
Experimental Sample ◽  
Current Densities ◽  
Transcranial Electric Stimulation ◽  
Anatomical Properties ◽  
Underlying Mechanisms

AbstractTranscranial electric stimulation (tES) induces electric fields that are subject to a complex interaction with individual anatomical properties, such as the low-conducting human skull, the distribution of cerebrospinal fluid or the sulcal depth, as well as stimulation target location and orientation. This complex interaction might contribute to the heterogenous results that are commonly observed in applications of tES in humans. Targeted tES, on the other hand, might be able to account for some of these individual factors. In the present study, we used the finite-element method (FEM) and head models of twenty-one participants to evaluate the effect of individually targeted tES on simulated intracranial current densities. Head models were based on an automated segmentation algorithm to facilitate processing in experimental sample sizes. We compared a standard stimulation montage to two individually optimized tES montages using an Alternating Direction Method of Multipliers (ADMM) and a Constrained Maximum Intensity (CMI) approach. A right parietal target was defined with three different orientations. Individual current densities showed varying intensity and spatial extent near the lower limit at which physiological efficacy of electric fields can be assumed. Both individually optimized targeting algorithms were able to control the electric field properties, with respect to intensities and/or spatial extent of the electric fields. Still, across head models, intensity in the stimulation target was constrained by individual anatomical properties. Thus, our results underline the importance of targeted tES in enhancing the effectiveness of future tES applications and in elucidating the underlying mechanisms.

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 Correction: Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Yu Huang ◽  
Anli A Liu ◽  
Belen Lafon ◽  
Daniel Friedman ◽  
Michael Dayan ◽  
...  
Keyword(s):  
Human Brain ◽  
Electric Fields ◽  
Electric Stimulation ◽  
Transcranial Electric Stimulation
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