scholarly journals Electric Field Model of Transcranial Electric Stimulation in Nonhuman Primates: Correspondence to Individual Motor Threshold

2015 ◽  
Vol 62 (9) ◽  
pp. 2095-2105 ◽  
Author(s):  
Won Hee Lee ◽  
Sarah H. Lisanby ◽  
Andrew F. Laine ◽  
Angel V. Peterchev
Keyword(s):  
Electric Field ◽  
Electric Stimulation ◽  
Nonhuman Primates ◽  
Field Model ◽  
Motor Threshold ◽  
Transcranial Electric Stimulation ◽  
Individual Motor

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 Electric Field Dynamics in the Brain During Multi-Electrode Transcranial Electric Stimulation

2018 ◽  
Author(s):  
Ivan Alekseichuk ◽  
Arnaud Y. Falchier ◽  
Gary Linn ◽  
Ting Xu ◽  
Michael P. Milham ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Stimulation ◽  
Brain Regions ◽  
Neural Oscillations ◽  
Non Invasive ◽  
Multiple Electrodes ◽  
Transcranial Electric Stimulation ◽  
Mechanistic Understanding ◽  
Linear Manner ◽  
The Brain

ABSTRACTNeural oscillations play a crucial role in communication between remote brain areas. Transcranial electric stimulation with alternating currents (TACS) can manipulate these brain oscillations in a non-invasive manner. Of particular interest, TACS protocols using multiple electrodes with phase shifted stimulation currents were developed to alter the connectivity between two or more brain regions. Typically, an increase in coordination between two sites is assumed when they experience an in-phase stimulation and a disorganization through an anti-phase stimulation. However, the underlying biophysics of multi-electrode TACS has not been studied in detail, thus limiting our ability to develop a mechanistic understanding. Here, we leverage direct invasive recordings from two non-human primates during multi-electrode TACS to show that the electric field magnitude and phase depend on the phase of the stimulation currents in a non-linear manner. Further, we report a novel phenomenon of a “traveling wave” stimulation where the location of the electric field maximum changes over the stimulation cycle. Our results provide a basis for a mechanistic understanding of multi-electrode TACS, necessitating the reevaluation of previously published studies, and enable future developments of novel stimulation protocols.

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 Optimizing the Electric Field Strength in Multiple Targets for Multichannel Transcranial Electric Stimulation

2020 ◽  
Author(s):  
Guilherme B. Saturnino ◽  
Kristoffer H. Madsen ◽  
Axel Thielscher
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Optimization Algorithm ◽  
Electric Stimulation ◽  
Field Direction ◽  
Field Pattern ◽  
Test Case ◽  
Preferred Direction ◽  
Transcranial Electric Stimulation

AbstractObjectiveMost approaches to optimize the electric field pattern generated by multichannel Transcranial Electric Stimulation (TES) require the definition of a preferred direction of the electric field in the target region(s). However, this requires knowledge about how the neural effects depend on the field direction, which is not always available. Thus, it can be preferential to optimize the field strength in the target(s), irrespective of the field direction. However, this results in a more complex optimization problem.ApproachWe introduce and validate a novel optimization algorithm that maximizes focality while controlling the electric field strength in the target to maintain a defined value. It obeys the safety constraints, allows limiting the number of active electrodes and allows also for multi-target optimization.Main ResultsThe optimization algorithm outperformed naïve search approaches in both quality of the solution and computational efficiency. Using the amygdala as test case, we show that it allows for reaching a reasonable trade-off between focality and field strength in the target. In contrast, simply maximizing the field strength in the target results in far more extended fields. In addition, by maintaining the pre-defined field strengths in the targets, the new algorithm allows for a balanced stimulation of two or more regions.SignificanceThe novel algorithm can be used to automatically obtain individualized, optimal montages for targeting regions without the need to define preferential directions. It will automatically select the field direction that achieves the desired field strength in the target(s) with the most focal stimulation pattern.

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.

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