Electroconvulsive therapy, electric field, neuroplasticity, and clinical outcomes

AbstractElectroconvulsive therapy (ECT) remains the gold-standard treatment for patients with depressive episodes, but the underlying mechanisms for antidepressant response and procedure-induced cognitive side effects have yet to be elucidated. Such mechanisms may be complex and involve certain ECT parameters and brain regions. Regarding parameters, the electrode placement (right unilateral or bitemporal) determines the geometric shape of the electric field (E-field), and amplitude determines the E-field magnitude in select brain regions (e.g., hippocampus). Here, we aim to determine the relationships between hippocampal E-field strength, hippocampal neuroplasticity, and antidepressant and cognitive outcomes. We used hippocampal E-fields and volumes generated from a randomized clinical trial that compared right unilateral electrode placement with different pulse amplitudes (600, 700, and 800 mA). Hippocampal E-field strength was variable but increased with each amplitude arm. We demonstrated a linear relationship between right hippocampal E-field and right hippocampal neuroplasticity. Right hippocampal neuroplasticity mediated right hippocampal E-field and antidepressant outcomes. In contrast, right hippocampal E-field was directly related to cognitive outcomes as measured by phonemic fluency. We used receiver operating characteristic curves to determine that the maximal right hippocampal E-field associated with cognitive safety was 112.5 V/m. Right hippocampal E-field strength was related to the whole-brain ratio of E-field strength per unit of stimulation current, but this whole-brain ratio was unrelated to antidepressant or cognitive outcomes. We discuss the implications of optimal hippocampal E-field dosing to maximize antidepressant outcomes and cognitive safety with individualized amplitudes.

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Identifying regions in prefrontal cortex related to working memory improvement: a novel meta-analytic method using electric field modeling

10.1101/2021.03.11.435002 ◽

2021 ◽

Author(s):

Miles Wischnewski ◽

Kathleen E. Mantell ◽

Alexander Opitz

Keyword(s):

Working Memory ◽

Prefrontal Cortex ◽

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Electric Fields ◽

Brain Regions ◽

Medium Effect ◽

Analytic Method ◽

List Type

AbstractAltering cortical activity using transcranial direct current stimulation (tDCS) has been shown to improve working memory (WM) performance. Due to large inter-experimental variability in the tDCS montage configuration and strength of induced electric fields, results have been mixed. Here, we present a novel meta-analytic method relating behavioral effect sizes to electric field strength to identify brain regions underlying largest tDCS-induced WM improvement. Simulations on 69 studies targeting left prefrontal cortex showed that tDCS electric field strength in lower dorsolateral prefrontal cortex (Brodmann area 45/47) relates most strongly to improved WM performance. This region explained 7.8% of variance, equaling a medium effect. A similar region was identified when correlating WM performance and electric field strength of right prefrontal tDCS studies (n = 18). Maximum electric field strength of five previously used tDCS configurations were outside of this location. We thus propose a new tDCS montage which maximizes the tDCS electric field strength in that brain region. Our findings can benefit future tDCS studies that aim to affect WM function.Highlights-We summarize the effect of 87 tDCS studies on working memory performance-We introduce a new meta-analytic method correlating tDCS electric fields and performance-tDCS-induced electric fields in lower DLPFC correlate significantly with improved working memory-The lower DLPFC was not maximally targeted by most tDCS montages and we provide an optimized montage

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P079 Electroconvulsive therapy induced hippocampal electric field strength and structural plasticity

Clinical Neurophysiology ◽

10.1016/j.clinph.2016.10.204 ◽

2017 ◽

Vol 128 (3) ◽

pp. e45

Author(s):

Z.- D. Deng ◽

C. Abbott

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Electroconvulsive Therapy ◽

Structural Plasticity

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Computational comparison of conventional and novel electroconvulsive therapy electrode placements for the treatment of depression

European Psychiatry ◽

10.1016/j.eurpsy.2019.05.006 ◽

2019 ◽

Vol 60 ◽

pp. 71-78 ◽

Cited By ~ 2

Author(s):

Siwei Bai ◽

Donel Martin ◽

Tianruo Guo ◽

Socrates Dokos ◽

Colleen Loo

Keyword(s):

Electroconvulsive Therapy ◽

Regional Differences ◽

Computational Modelling ◽

Human Head ◽

Brain Regions ◽

Electrical Stimulus ◽

Electrode Placement ◽

Treatment Of Depression ◽

Mri Scans ◽

Average Electric Field

AbstractBackground:Electroconvulsive therapy (ECT) is a highly effective treatment for severe psychiatric disorders. Despite its high efficacy, the use of ECT would be greater if the risk of cognitive side effects were reduced. Over the last 20 years, developments in ECT technique, including improvements in the dosing methodology and modification of the stimulus waveform, have allowed for improved treatment methods with reduced adverse cognitive effects. There is increasing evidence that the electrode placement is important for orienting the electrical stimulus and therefore modifying treatment outcomes, with potential for further improvement of the placements currently used in ECT.Objective:We used computational modelling to perform an in-depth examination into regional differences in brain excitation by the ECT stimulus for several lesser known and novel electrode placements, in order to investigate the potential for an electrode placement that may optimise clinical outcomes.Methods:High resolution finite element human head models were generated from MRI scans of three subjects. The models were used to compare regional differences in average electric field (EF) magnitude among a total of thirteen bipolar ECT electrode placements, i.e. three conventional placements as well as ten lesser known and novel placements.Results and conclusion:In this exploratory study on a systemic comparison of thirteen ECT electrode placements, the EF magnitude at regions of interest (ROIs) was highly dependent upon the position of both electrodes, especially the ROIs close to the cortical surface. Compared to conventional right-unilateral (RUL) ECT using a temporo-parietal placement, fronto-parietal and supraorbito-parietal RUL also robustly stimulated brain regions considered important for efficacy, while sparing regions related to cognitive functions, and may be a preferrable approach to the currently used placement for RUL ECT. The simulations also found that regional average EF magnitude varied between individual subjects, due to factors such as head size, and results also depended on the size of the defined ROI.

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Electroconvulsive therapy (ECT) during pregnancy: quantifying and assessing the electric field strength inside the foetal brain

Scientific Reports ◽

10.1038/s41598-018-22528-x ◽

2018 ◽

Vol 8 (1) ◽

Cited By ~ 2

Author(s):

Behailu Kibret ◽

Malin Premaratne ◽

Caley Sullivan ◽

Richard H. Thomson ◽

Paul B. Fitzgerald

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Electroconvulsive Therapy ◽

Foetal Brain

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Uncovering the underlying mechanisms and whole-brain dynamics of therapeutic deep brain stimulation for Parkinson's disease

10.1101/083162 ◽

2016 ◽

Author(s):

Victor M Saenger ◽

Joshua Kahan ◽

Tom Foltynie ◽

Karl Friston ◽

Tipu Z Aziz ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Deep Brain Stimulation ◽

Brain Stimulation ◽

Resting State Fmri ◽

Brain Regions ◽

Brain Dynamics ◽

Whole Brain ◽

Underlying Mechanisms ◽

Deep Brain

Deep brain stimulation (DBS) for Parkinson's disease is a highly effective treatment in controlling otherwise debilitating symptoms yet the underlying brain mechanisms are currently not well understood. We used whole-brain computational modeling to disclose the effects of DBS ON and OFF during collection of resting state fMRI in ten Parkinson's Disease patients. Specifically, we explored the local and global impact of DBS in creating asynchronous, stable or critical oscillatory conditions using a supercritical bifurcation model. We found that DBS shifts the global brain dynamics of patients nearer to that of healthy people by significantly changing the bifurcation parameters in brain regions implicated in Parkinson's Disease. We also found higher communicability and coherence brain measures during DBS ON compared to DBS OFF. Finally, by modeling stimulation we identified possible novel DBS targets. These results offer important insights into the underlying effects of DBS, which may in time offer a route to more efficacious treatments.

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Electric Field Controlled Indirect-Direct-Indirect Band Gap Transition in Monolayer InSe

Nanoscale Research Letters ◽

10.1186/s11671-019-3162-0 ◽

2019 ◽

Vol 14 (1) ◽

Author(s):

Xian-Bo Xiao ◽

Qian Ye ◽

Zheng-Fang Liu ◽

Qing-Ping Wu ◽

Yuan Li ◽

...

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Band Gap ◽

Energy Band ◽

Electronic Structures ◽

Optoelectronic Devices ◽

Group Iii ◽

Underlying Mechanisms ◽

Indirect Band Gap

Abstract Electronic structures of monolayer InSe with a perpendicular electric field are investigated. Indirect-direct-indirect band gap transition is found in monolayer InSe as the electric field strength is increased continuously. Meanwhile, the global band gap is suppressed gradually to zero, indicating that semiconductor-metal transformation happens. The underlying mechanisms are revealed by analyzing both the orbital contributions to energy band and evolution of band edges. These findings may not only facilitate our further understanding of electronic characteristics of layered group III-VI semiconductors, but also provide useful guidance for designing optoelectronic devices.

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Rapid whole-brain electric field mapping in transcranial magnetic stimulation using deep learning

PLoS ONE ◽

10.1371/journal.pone.0254588 ◽

2021 ◽

Vol 16 (7) ◽

pp. e0254588

Author(s):

Guoping Xu ◽

Yogesh Rathi ◽

Joan A. Camprodon ◽

Hanqiang Cao ◽

Lipeng Ning

Keyword(s):

Neural Network ◽

Transcranial Magnetic Stimulation ◽

Electric Field ◽

Network Architecture ◽

Magnetic Stimulation ◽

Complex Structure ◽

Brain Regions ◽

Imaging Data ◽

Feature Maps ◽

Whole Brain

Transcranial magnetic stimulation (TMS) is a non-invasive neurostimulation technique that is increasingly used in the treatment of neuropsychiatric disorders and neuroscience research. Due to the complex structure of the brain and the electrical conductivity variation across subjects, identification of subject-specific brain regions for TMS is important to improve the treatment efficacy and understand the mechanism of treatment response. Numerical computations have been used to estimate the stimulated electric field (E-field) by TMS in brain tissue. But the relative long computation time limits the application of this approach. In this paper, we propose a deep-neural-network based approach to expedite the estimation of whole-brain E-field by using a neural network architecture, named 3D-MSResUnet and multimodal imaging data. The 3D-MSResUnet network integrates the 3D U-net architecture, residual modules and a mechanism to combine multi-scale feature maps. It is trained using a large dataset with finite element method (FEM) based E-field and diffusion magnetic resonance imaging (MRI) based anisotropic volume conductivity or anatomical images. The performance of 3D-MSResUnet is evaluated using several evaluation metrics and different combinations of imaging modalities and coils. The experimental results show that the output E-field of 3D-MSResUnet provides reliable estimation of the E-field estimated by the state-of-the-art FEM method with significant reduction in prediction time to about 0.24 second. Thus, this study demonstrates that neural networks are potentially useful tools to accelerate the prediction of E-field for TMS targeting.

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