scholarly journals A Future of Current Flow Modelling for Transcranial Electrical Stimulation?

2021 ◽  
Author(s):  
J. S. A. Lee ◽  
S. Bestmann ◽  
C. Evans
Keyword(s):  
Electrical Stimulation ◽  
Current Flow ◽  
Brain Activity ◽  
Cost Effective ◽  
Electrical Current ◽  
Transcranial Electrical Stimulation ◽  
Concentric Spheres ◽  
Mri Scans ◽  
Dose Control ◽  
Health And Disease

Abstract Purpose of Review Transcranial electrical stimulation (tES) is used to non-invasively modulate brain activity in health and disease. Current flow modeling (CFM) provides estimates of where and how much electrical current is delivered to in the brain during tES. It therefore holds promise as a method to reduce commonplace variability in tES delivery and, in turn, the outcomes of stimulation. However, the adoption of CFM has not yet been widespread and its impact on tES outcome variability is unclear. Here, we discuss the potential barriers to effective, practical CFM-informed tES use. Recent Findings CFM has progressed from models based on concentric spheres to gyri-precise head models derived from individual MRI scans. Users can now estimate the intensity of electrical fields (E-fields), their spatial extent, and the direction of current flow in a target brain region during tES. Here. we consider the multi-dimensional challenge of implementing CFM to optimise stimulation dose: this requires informed decisions to prioritise E-field characteristics most likely to result in desired stimulation outcomes, though the physiological consequences of the modelled current flow are often unknown. Second, we address the issue of a disconnect between predictions of E-field characteristics provided by CFMs and predictions of the physiological consequences of stimulation which CFMs are not designed to address. Third, we discuss how ongoing development of CFM in conjunction with other modelling approaches could overcome these challenges while maintaining accessibility for widespread use. Summary The increasing complexity and sophistication of CFM is a mandatory step towards dose control and precise, individualised delivery of tES. However, it also risks counteracting the appeal of tES as a straightforward, cost-effective tool for neuromodulation, particularly in clinical settings.

scholarly journals A future of current flow modelling for transcranial electrical stimulation?

2021 ◽  
Author(s):  
Jenny lee ◽  
Sven Bestmann ◽  
Carys Evans
Keyword(s):  
Electrical Stimulation ◽  
Current Flow ◽  
Brain Activity ◽  
Cost Effective ◽  
Electrical Current ◽  
Transcranial Electrical Stimulation ◽  
Clinical Settings ◽  
Dose Control ◽  
Health And Disease ◽  
The Brain

Transcranial electrical stimulation (tES) is used to non-invasively modulate brain activity in health and disease. Current flow modeling (CFM) provides estimates of where, and how much electrical current is delivered to the brain during tES. It therefore holds promise as a method to reduce commonplace variability in tES delivery and, in turn, the outcomes of stimulation. However, the adoption of CFM has not yet been widespread and its impact on tES outcome variability is unclear. Here we discuss the potential barriers to effective, practical CFM-informed tES use. We first consider the multi-dimensional challenge of optimising stimulation dose. CFMs estimate the intensity of electrical fields (E-fields), their spatial extent, and the direction of current flow in a target brain region during tES. Researchers must make informed decisions to prioritise E-field characteristics most likely to result in desired stimulation outcomes, though the physiological consequences of the modelled current flow are often unknown. Second, we address the issue of a disconnect between predictions of E-field characteristics provided by CFMs, and predictions of the physiological consequences of stimulation which CFMs are not designed to address. Third, we discuss how ongoing development of CFM in conjunction with other modelling approaches could overcome these challenges while maintaining accessibility for widespread use. The increasing complexity and sophistication of CFM is a mandatory step towards dose control and precise, individualised delivery of tES, but also risks counteracting the appeal of tES as a straight-forward, cost effective tool for neuromodulation, particularly in clinical settings.

Transcranial Electrical Stimulation and Recording of Brain Activity using Freestanding Plant‐Based Conducting Polymer Hydrogel Composites

2019 ◽  
Vol 5 (3) ◽  
pp. 1900652 ◽  
Author(s):  
George D. Spyropoulos ◽  
Jeremy Savarin ◽  
Eliot F. Gomez ◽  
Daniel T. Simon ◽  
Magnus Berggren ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Conducting Polymer ◽  
Brain Activity ◽  
Transcranial Electrical Stimulation ◽  
Polymer Hydrogel ◽  
Hydrogel Composites

Transcranial Electrical and Magnetic Stimulation

2017 ◽  
Author(s):  
Alexander Rotenberg ◽  
Alvaro Pascual-Leone ◽  
Alan D. Legatt
Keyword(s):  
Electrical Stimulation ◽  
Direct Current ◽  
Action Potentials ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Electrical Current ◽  
Cortical Mapping ◽  
Transcranial Electrical Stimulation ◽  
Advanced Stages ◽  
Low Amplitude

Noninvasive magnetic and electrical stimulation of cerebral cortex is an evolving field. The most widely used variant, transcranial electrical stimulation (TES), is routinely used for intraoperative monitoring. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are emerging as clinical and experimental tools. TMS has gained wide acceptance in extraoperative functional cortical mapping. TES and TMS rely on pulsatile stimulation with electrical current intensities sufficient to trigger action potentials within the stimulated cortical volume. tDCS, in contrast, is based on neuromodulatory effects of very-low-amplitude direct current conducted through the scalp. tDCS and TMS, particularly when applied in repetitive trains, can modulate cortical excitability for prolonged periods and thus are either in active clinical use or in advanced stages of clinical trials for common neurological and psychiatric disorders such as major depression and epilepsy. This chapter summarizes physiologic principles of transcranial stimulation and clinical applications of these techniques.

Does Transcranial Electrical Stimulation Induce Changes in Peripheral Physiology?

2017 ◽  
Vol 41 (S1) ◽  
pp. S33-S33
Author(s):  
S. Lehto
Keyword(s):  
Electrical Stimulation ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Neuronal Excitability ◽  
Brain Activity ◽  
Brain Structures ◽  
Point Of View ◽  
Transcranial Electrical Stimulation ◽  
Dorsolateral Prefrontal ◽  
Competing Interest

Transcranial electrical stimulation (tES) is a non-invasive brain stimulation method that has evoked increasing interest during the past years. The most common form of tES, transcranial direct current stimulation (tDCS), is considered to modulate neuronal resting potentials. For example, anodal stimulation over motor cortex appears to lead to increased neuronal excitability under the stimulation electrodes. However, some recent findings suggest that the effects of tDCS extend beyond the cortical areas under the electrodes, to deeper brain structures such as the midbrain. The brain also actively regulates peripheral physiology. Thus, changes in brain activity following tES may lead to modulation of peripheral physiology. For example, tDCS targeting primary motor cortex has been observed to induce changes in peripheral glucose metabolism. Furthermore, stimulation of dorsolateral prefrontal cortex has been shown to lead to alterations in cortisol secretion and the activity of the autonomic nervous system. Unpublished findings from our group corroborate with the above observations. Nevertheless, the evidence regarding peripheral effects of tES remains limited. Investigating such possible effects may be relevant especially from the point of view of tES safety and potential therapeutic discoveries.Disclosure of interestThe author has not supplied his declaration of competing interest.

scholarly journals fMRI and Transcranial Electrical Stimulation (tES): A systematic review of parameter space and outcomes

2020 ◽  
Author(s):  
Peyman Ghobadi-Azbari ◽  
Asif Jamil ◽  
Fatemeh Yavari ◽  
Zeinab Esmaeilpour ◽  
Nastaran Malmir ◽  
...  
Keyword(s):  
Systematic Review ◽  
Electrical Stimulation ◽  
Parameter Space ◽  
Brain Activity ◽  
Random Noise ◽  
Brain Regions ◽  
Transcranial Electrical Stimulation ◽  
Future Studies ◽  
Non Invasive ◽  
And Behavior

AbstractThe combination of non-invasive brain stimulation interventions with human brain mapping methods have supported research beyond correlational associations between brain activity and behavior. Functional MRI (fMRI) partnered with transcranial electrical stimulation (tES) methods, i.e., transcranial direct current (tDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation, explore the neuromodulatory effects of tES in the targeted brain regions and their interconnected networks and provide opportunities for individualized interventions. Advances in the field of tES-fMRI can be hampered by the methodological variability between studies that confounds comparability/replicability. In order to explore variability in the tES-fMRI methodological parameter space (MPS), we conducted a systematic review of 222 tES-fMRI experiments (181 tDCS, 39 tACS and 2 tRNS) published before February 1, 2019, and suggested a framework to systematically report main elements of MPS across studies. We have organized main findings in terms of fMRI modulation by tES. tES modulates activation and connectivity beyond the stimulated areas particularly with prefrontal stimulation. There were no two studies with the same MPS to replicate findings. We discuss how to harmonize the MPS to promote replication in future studies.

scholarly journals Enhancement of Event-Related Desynchronization in Motor Imagery Based on Transcranial Electrical Stimulation

2021 ◽  
Vol 15 ◽  
Author(s):  
Jiaxin Xie ◽  
Maoqin Peng ◽  
Jingqing Lu ◽  
Chao Xiao ◽  
Xin Zong ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Imagery ◽  
Brain Activity ◽  
Transcranial Electrical Stimulation ◽  
Linear Discriminant ◽  
Left Hand ◽  
Event Related Desynchronization ◽  
Power Spectral ◽  
Transcranial Alternating Current Stimulation ◽  
The Individual

Due to the individual differences controlling brain-computer interfaces (BCIs), the applicability and accuracy of BCIs based on motor imagery (MI-BCIs) are limited. To improve the performance of BCIs, this article examined the effect of transcranial electrical stimulation (tES) on brain activity during MI. This article designed an experimental paradigm that combines tES and MI and examined the effects of tES based on the measurements of electroencephalogram (EEG) features in MI processing, including the power spectral density (PSD) and dynamic event-related desynchronization (ERD). Finally, we investigated the effect of tES on the accuracy of MI classification using linear discriminant analysis (LDA). The results showed that the ERD of the μ and β rhythms in the left-hand MI task was enhanced after electrical stimulation with a significant effect in the tDCS group. The average classification accuracy of the transcranial alternating current stimulation (tACS) group and transcranial direct current stimulation (tDCS) group (88.19% and 89.93% respectively) were improved significantly compared to the pre-and pseudo stimulation groups. These findings indicated that tES can improve the performance and applicability of BCI and that tDCS was a potential approach in regulating brain activity and enhancing valid features during noninvasive MI-BCI processing.

scholarly journals Transcranial Electrical Stimulation Motor Threshold Combined with Reverse-Calculated Electric Field Modeling Can Determine Individualized tDCS Dosage

2019 ◽  
Author(s):  
Kevin A. Caulfield ◽  
Bashar W. Badran ◽  
William H. DeVries ◽  
Philipp M. Summers ◽  
Emma Kofmehl ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Electric Field ◽  
Single Pulse ◽  
Structural Mri ◽  
Transcranial Electrical Stimulation ◽  
Motor Threshold ◽  
Quick Method ◽  
Easy Method ◽  
Field Modeling ◽  
Mri Scans

AbstractBackgroundUnique amongst brain stimulation tools, transcranial direct current stimulation (tDCS) currently lacks an easy method for individualizing dosage.ObjectiveCan one individually dose tDCS? We developed a novel method of reverse-calculating electric-field (E-field) models based on Magnetic Resonance Imaging (MRI) scans that can determine individualized tDCS dose. We also sought to develop an MRI-free method of individualizing tDCS dose by measuring transcranial magnetic stimulation (TMS) motor threshold (MT) and single pulse, suprathreshold transcranial electrical stimulation (TES) MT and regressing it against E-field modeling.MethodsIn 29 healthy adults, we acquired TMS MT, TES MT, and structural MRI scans with a fiducial marking the motor hotspot. We then computed a “reverse-calculated tDCS dose” of tDCS applied at the scalp needed to cause a 1.00V/m E-field at the cortex. Finally, we examined whether the predicted E-field values correlated with each participant’s measured TMS MT or TES MT.ResultsWe were able to determine a reverse-calculated tDCS dose for each participant. The Transcranial Electrical Stimulation MT, but not the Transcranial Magnetic Stimulation MT, significantly correlated with the calculated tDCS dose determined by E-field modeling (R2 = 0.509, p < 0.001).ConclusionsReverse-calculation E-field modeling, alone or in combination with TES MT, shows promise as a method to individualize tDCS dose. The large range of the reverse-calculated tDCS doses between subjects underscores the likely need to individualize tDCS dose. If these results are confirmed in future studies, TES MT may evolve into an inexpensive and quick method to individualize tDCS dose.

Transcranial Electrical Stimulation in Post-Stroke Cognitive Rehabilitation

2016 ◽  
Vol 21 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Silvia Convento ◽  
Cristina Russo ◽  
Luca Zigiotto ◽  
Nadia Bolognini
Keyword(s):  
Electrical Stimulation ◽  
Cognitive Rehabilitation ◽  
Cognitive Disorders ◽  
Spatial Neglect ◽  
Transcranial Electrical Stimulation ◽  
Clinical Settings ◽  
Post Stroke ◽  
Neuropsychological Disorders ◽  
Current State ◽  
Stimulation Technique

Abstract. Cognitive rehabilitation is an important area of neurological rehabilitation, which aims at the treatment of cognitive disorders due to acquired brain damage of different etiology, including stroke. Although the importance of cognitive rehabilitation for stroke survivors is well recognized, available cognitive treatments for neuropsychological disorders, such as spatial neglect, hemianopia, apraxia, and working memory, are overall still unsatisfactory. The growing body of evidence supporting the potential of the transcranial Electrical Stimulation (tES) as tool for interacting with neuroplasticity in the human brain, in turn for enhancing perceptual and cognitive functions, has obvious implications for the translation of this noninvasive brain stimulation technique into clinical settings, in particular for the development of tES as adjuvant tool for cognitive rehabilitation. The present review aims at presenting the current state of art concerning the use of tES for the improvement of post-stroke visual and cognitive deficits (except for aphasia and memory disorders), showing the therapeutic promises of this technique and offering some suggestions for the design of future clinical trials. Although this line of research is still in infancy, as compared to the progresses made in the last years in other neurorehabilitation domains, current findings appear very encouraging, supporting the development of tES for the treatment of post-stroke cognitive impairments.

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