scholarly journals Can transcranial electric stimulation with multiple electrodes reach deep targets?

2018 ◽  
Author(s):  
Yu Huang ◽  
Lucas C Parra
Keyword(s):  
Electric Stimulation ◽  
Target Location ◽  
Head Model ◽  
Multiple Electrodes ◽  
Realistic Head Model ◽  
Transcranial Electric Stimulation ◽  
The Brain ◽  
Deep Target ◽  
Deep Brain ◽  
Intense Stimulation

To reach a deep target in the brain with transcranial electric stimulation (TES), currents have to pass also through the cortical surface. Thus, it is generally thought that TES cannot achieve focal deep brain stimulation. Recent efforts with interfering waveforms and pulsed stimulation have argued that one can achieve deeper or more intense stimulation in the brain. Here we argue that conventional transcranial stimulation with multiple current sources is just as effective as these new approaches. The conventional multi-electrode approach can be numerically optimized to maximize intensity or focality at a desired target location. Using such optimal electrode configurations we find in a detailed and realistic head model that deep targets may in fact be strongly stimulated, with cerebrospinal fluid guiding currents deep into 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 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 Transcranial electric stimulation seen from within the brain

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Angel V Peterchev
Keyword(s):  
Electric Stimulation ◽  
Computer Models ◽  
Transcranial Electric Stimulation ◽  
The Brain

Computer models can make transcranial electric stimulation a better tool for research and therapy.

scholarly journals A flexible workflow for simulating transcranial electric stimulation in healthy and lesioned brains

2020 ◽  
Author(s):  
Benjamin Kalloch ◽  
Pierre-Louis Bazin ◽  
Arno Villringer ◽  
Bernhard Sehm ◽  
Mario Hlawitschka
Keyword(s):  
White Matter ◽  
Electric Stimulation ◽  
Diffusion Tensor ◽  
Head Model ◽  
Imaging Data ◽  
Mr Images ◽  
Anisotropic Conductivity ◽  
Irregular Structures ◽  
Transcranial Electric Stimulation ◽  
Air Cavities

AbstractSimulating transcranial electric stimulation is actively researched as knowledge about the distribution of the electrical field is decisive for understanding the variability in the elicited stimulation effect. Several software pipelines comprehensively solve this task in an automated manner for standard use-cases. However, simulations for non-standard applications such as uncommon electrode shapes or the creation of head models from non-optimized T1-weighted imaging data and the inclusion of irregular structures are more difficult to accomplish.We address these limitations and suggest a comprehensive workflow to simulate transcranial electric stimulation based on open-source tools. The workflow covers the head model creation from MRI data, the electrode modeling, the modeling of anisotropic conductivity behavior of the white matter, the numerical simulation and visualization.Skin, skull, air cavities, cerebrospinal fluid, white matter, and gray matter are segmented semi-automatically from T1-weighted MR images. Electrodes of arbitrary number and shape can be modeled. The meshing of the head model is implemented in a way to preserve feature edges of the electrodes and is free of topological restrictions of the considered structures of the head model. White matter anisotropy can be computed from diffusion-tensor imaging data.Our solver application was verified analytically and by contrasting tDCS simulation results with another simulation pipeline (SimNIBS 3.0). An agreement in both cases underlines the validity of our workflow.Our suggested solutions facilitate investigations of irregular structures in patients (e.g. lesions, implants) or of new electrode types. For a coupled use of the described workflow, we provide documentation and disclose the full source code of the developed tools.

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 EEG Deblurring Techniques in a Clinical Context

2004 ◽  
Vol 43 (01) ◽  
pp. 114-117 ◽  
Author(s):  
F. Cincotti ◽  
C. Babiloni ◽  
C. Miniussi ◽  
F. Carducci ◽  
D. Moretti ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Magnetic Resonance Images ◽  
Head Model ◽  
Clinical Environment ◽  
Clinical Context ◽  
Time Period ◽  
Realistic Head Model ◽  
Eeg Data ◽  
Eeg Recordings ◽  
The Brain

Summary Objectives: EEG scalp potential distributions recorded in humans are affected by low spatial resolution and by the dependence on the electrical reference used. High resolution EEG technologies are available to drastically increase the spatial resolution of the raw EEG. Such technologies include the computation of surface Laplacian (SL) of the recorded potentials, as well as the use of realistic head models to estimate the cortical sources via linear inverse procedure (low resolution brain electromagnetic tomography, LORETA). However, these deblurring procedures are generally used in conjunction with EEG recordings with 64-128 scalp electrodes and with realistic head models obtained via sequential magnetic resonance images (MRIs) of the subjects. Such recording setup it is not often available in the clinical context, due to both the unavailability of these technologies and the scarce compliance of the patients with them. In this study we addressed the use of SL and LORETA deblurring techniques to analyze data from a standard 10-20 system (19 electrodes) in a group of Alzheimer disease (AD) patients. Methods: EEG data related to unilateral finger movements were gathered from 10 patients affected by AD. SL and LORETA techniques were applied for source estimation of EEG data. The use of MRIs for the construction of head models was avoided by using the quasi-realistic head model of the Brain Imaging Neurology Institute of Montreal. Results: A similar cortical activity estimated by the SL and LORETA techniques was observed during an identical time period of the acquired EEG data in the examined population. Conclusions: The results of the present study suggest that both SL and LORETA approaches can be usefully applied in the clinical context, by using quasi-realistic head modeling and a standard 10-20 system as electrode montage (19 electrodes). These results represent a reciprocal cross-validation of the two mathematically independent techniques in a clinical environment.

Uncertainty quantification and sensitivity analysis of transcranial electric stimulation for 9-subdomain human head model

2022 ◽  
Vol 135 ◽  
pp. 1-11
Author(s):  
Anna Šušnjara ◽  
Ožbej Verhnjak ◽  
Dragan Poljak ◽  
Mario Cvetković ◽  
Jure Ravnik
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Quantification ◽  
Electric Stimulation ◽  
Human Head ◽  
Head Model ◽  
Transcranial Electric Stimulation ◽  
Human Head Model

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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