scholarly journals Group-Level Analysis of Induced Electric Field in Deep Brain Regions by Different TMS Coils

2019 ◽  
Author(s):  
Jose Gomez-Tames ◽  
Atsushi Hamasaka ◽  
Akimasa Hirata ◽  
Ilkka Laakso ◽  
Mai Lu ◽  
...  
Keyword(s):  
Electric Fields ◽  
Brain Regions ◽  
Invasive Technique ◽  
Group Level ◽  
Registration Method ◽  
Non Invasive ◽  
Consistent Group ◽  
Coil Performance ◽  
Deep Brain Region ◽  
Deep Brain

AbstractDeep transcranial magnetic stimulation (dTMS) is a non-invasive technique used in treating depression. In this study, we computationally evaluate group-level dosage during dTMS with the aim of characterizing targeted deep brain regions to overcome the limitation of using individualized head models to characterize coil performance in a population.We use an inter-subject registration method adapted to deep brain regions that enable projection of computed electric fields (EFs) from individual realistic head models (n= 18) to the average space of deep brain regions. The computational results showed consistent group-level hotspots of the EF in deep brain region with intensities between 20%-50% of the maximum EF in the cortex. Large co-activation in other brain regions was confirmed while half-value penetration depth from the cortical surface was smaller than 2 cm. The halo figure-8 assembly and halo circular assembly coils induced the highest EFs for caudate, putamen, and hippocampus.Generalized induced EF maps of deep regions show target regions despite inter-individual difference. This is the first study that visualizes generalized target regions during dTMS and provides a method for making informed decisions during dTMS interventions in clinical practice.

scholarly journals Interindividual variability of electric fields during transcranial temporal interference stimulation (tTIS)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jill von Conta ◽  
Florian H. Kasten ◽  
Branislava Ćurčić-Blake ◽  
André Aleman ◽  
Axel Thielscher ◽  
...  
Keyword(s):  
Electric Fields ◽  
Interindividual Variability ◽  
Brain Regions ◽  
Single Subject ◽  
Non Invasive ◽  
Left Hippocampus ◽  
Potential Benefits ◽  
Stimulation Technique ◽  
Deep Brain ◽  
Stimulation Of

AbstractTranscranial temporal interference stimulation (tTIS) is a novel non-invasive brain stimulation technique for electrical stimulation of neurons at depth. Deep brain regions are generally small in size, making precise targeting a necessity. The variability of electric fields across individual subjects resulting from the same tTIS montages is unknown so far and may be of major concern for precise tTIS targeting. Therefore, the aim of the current study is to investigate the variability of the electric fields due to tTIS across 25 subjects. To this end, the electric fields of different electrode montages consisting of two electrode pairs with different center frequencies were simulated in order to target selected regions-of-interest (ROIs) with tTIS. Moreover, we set out to compare the electric fields of tTIS with the electric fields of conventional tACS. The latter were also based on two electrode pairs, which, however, were driven in phase at a common frequency. Our results showed that the electric field strengths inside the ROIs (left hippocampus, left motor area and thalamus) during tTIS are variable on single subject level. In addition, tTIS stimulates more focally as compared to tACS with much weaker co-stimulation of cortical areas close to the stimulation electrodes. Electric fields inside the ROI were, however, comparable for both methods. Overall, our results emphasize the potential benefits of tTIS for the stimulation of deep targets, over conventional tACS. However, they also indicate a need for individualized stimulation montages to leverage the method to its fullest potential.

scholarly journals Orientation of Temporal Interference for Non-Invasive Deep Brain Stimulation in Epilepsy

2020 ◽  
Author(s):  
Florian Missey ◽  
Evgeniia Rusina ◽  
Emma Acerbo ◽  
Boris Botzanowski ◽  
Romain Carron ◽  
...  
Keyword(s):  
Electric Fields ◽  
Brain Regions ◽  
Intracranial Stimulation ◽  
Epileptogenic Zone ◽  
Implanted Electrodes ◽  
Non Invasive ◽  
Gamma Range ◽  
Wide Range ◽  
Drug Resistant Epilepsy ◽  
Intracranial Electrodes

AbstractIn patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on nonpenetrating surface electrodes, namely an orientation-tunable form of temporally-interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally-invasive temporally-interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue.

scholarly journals Deep Learning for Non-Invasive Cortical Potential Imaging

2020 ◽  
Author(s):  
Alexandra Razorenova ◽  
Nikolay Yavich ◽  
Mikhail Malovichko ◽  
Maxim Fedorov ◽  
Nikolay Koshev ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Deep Learning ◽  
Electric Fields ◽  
Spatial Resolution ◽  
Brain Activity ◽  
Invasive Technique ◽  
Problem Solver ◽  
Deep Convolutional Neural Networks ◽  
Non Invasive ◽  
Cortical Potential Imaging

AbstractElectroencephalography (EEG) is a well-established non-invasive technique to measure the brain activity, albeit with a limited spatial resolution. Variations in electric conductivity between different tissues distort the electric fields generated by cortical sources, resulting in smeared potential measurements on the scalp. One needs to solve an ill-posed inverse problem to recover the original neural activity. In this article, we present a generic method of recovering the cortical potentials from the EEG measurement by introducing a new inverse-problem solver based on deep Convolutional Neural Networks (CNN) in paired (U-Net) and unpaired (DualGAN) configurations. The solvers were trained on synthetic EEG-ECoG pairs that were generated using a head conductivity model computed using the Finite Element Method (FEM). These solvers are the first of their kind, that provide robust translation of EEG data to the cortex surface using deep learning. Providing a fast and accurate interpretation of the tracked EEG signal, our approach promises a boost to the spatial resolution of the future EEG devices.

scholarly journals Orientation of Temporal Interference for Non-invasive Deep Brain Stimulation in Epilepsy

2021 ◽  
Vol 15 ◽  
Author(s):  
Florian Missey ◽  
Evgeniia Rusina ◽  
Emma Acerbo ◽  
Boris Botzanowski ◽  
Agnès Trébuchon ◽  
...  
Keyword(s):  
Electric Fields ◽  
Pulse Width Modulation ◽  
Brain Regions ◽  
Intracranial Stimulation ◽  
Epileptogenic Zone ◽  
Implanted Electrodes ◽  
Non Invasive ◽  
Gamma Range ◽  
Wide Range ◽  
Drug Resistant Epilepsy

In patients with focal drug-resistant epilepsy, electrical stimulation from intracranial electrodes is frequently used for the localization of seizure onset zones and related pathological networks. The ability of electrically stimulated tissue to generate beta and gamma range oscillations, called rapid-discharges, is a frequent indication of an epileptogenic zone. However, a limit of intracranial stimulation is the fixed physical location and number of implanted electrodes, leaving numerous clinically and functionally relevant brain regions unexplored. Here, we demonstrate an alternative technique relying exclusively on non-penetrating surface electrodes, namely an orientation-tunable form of temporally interfering (TI) electric fields to target the CA3 of the mouse hippocampus which focally evokes seizure-like events (SLEs) having the characteristic frequencies of rapid-discharges, but without the necessity of the implanted electrodes. The orientation of the topical electrodes with respect to the orientation of the hippocampus is demonstrated to strongly control the threshold for evoking SLEs. Additionally, we demonstrate the use of Pulse-width-modulation of square waves as an alternative to sine waves for TI stimulation. An orientation-dependent analysis of classic implanted electrodes to evoke SLEs in the hippocampus is subsequently utilized to support the results of the minimally invasive temporally interfering fields. The principles of orientation-tunable TI stimulation seen here can be generally applicable in a wide range of other excitable tissues and brain regions, overcoming several limitations of fixed electrodes which penetrate tissue and overcoming several limitations of other non-invasive stimulation methods in epilepsy, such as transcranial magnetic stimulation (TMS).

scholarly journals Temporal interference stimulation targets deep brain regions by modulating neural oscillations

2019 ◽  
Author(s):  
Zeinab Esmaeilpour ◽  
Greg Kronberg ◽  
Davide Reato ◽  
Lucas C Parra ◽  
Marom Bikson
Keyword(s):  
Electric Fields ◽  
Modulation Frequency ◽  
Hippocampal Slices ◽  
Human Head ◽  
Gamma Oscillations ◽  
Brain Regions ◽  
Neural Oscillations ◽  
Neuronal Membrane ◽  
Underlying Mechanisms ◽  
Deep Brain

AbstractTemporal interference (TI) stimulation of the brain generates amplitude-modulated electric fields oscillating in the kHz range. A validated current-flow model of the human head estimates that amplitude-modulated electric fields are stronger in deep brain regions, while unmodulated electric fields are maximal at the cortical regions. The electric field threshold to modulate carbachol-induced gamma oscillations in rat hippocampal slices was determined for unmodulated 0.05-2 kHz sine waveforms, and 5 Hz amplitude-modulated waveforms with 0.1-2 kHz carrier frequencies. The neuronal effects are replicated with a computational network model to explore the underlying mechanisms. Experiment and model confirm the hypothesis that spatial selectivity of temporal interference stimulation depends on the phasic modulation of neural oscillations only in deep brain regions. This selectivity is governed by network adaption (e.g. GABAb) that is faster than the amplitude-modulation frequency. The applied current required depends on the neuronal membrane time-constant (e.g. axons) approaching the kHz carrier frequency of temporal interference stimulation.

scholarly journals Magnetically Induced Temporal Interference for Focal and Deep-Brain Stimulation

2021 ◽  
Vol 15 ◽  
Author(s):  
Zonghao Xin ◽  
Akihiro Kuwahata ◽  
Shuang Liu ◽  
Masaki Sekino
Keyword(s):  
Deep Brain Stimulation ◽  
Electric Field ◽  
Brain Stimulation ◽  
Magnetic Stimulation ◽  
Brain Regions ◽  
Potential Candidate ◽  
Non Invasive ◽  
Neural Modulation ◽  
Stimulation Method ◽  
Deep Brain

Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique that has been clinically applied for neural modulation. Conventional TMS systems are restricted by the trade-off between depth penetration and the focality of the induced electric field. In this study, we integrated the concept of temporal interference (TI) stimulation, which has been demonstrated as a non-invasive deep-brain stimulation method, with magnetic stimulation in a four-coil configuration. The attenuation depth and spread of the electric field were obtained by performing numerical simulation. Consequently, the proposed temporally interfered magnetic stimulation scheme was demonstrated to be capable of stimulating deeper regions of the brain model while maintaining a relatively narrow spread of the electric field, in comparison to conventional TMS systems. These results demonstrate that TI magnetic stimulation could be a potential candidate to recruit brain regions underneath the cortex. Additionally, by controlling the geometry of the coil array, an analogous relationship between the field depth and focality was observed, in the case of the newly proposed method. The major limitations of the methods, however, would be the considerable intensity and frequency of the input current, followed by the frustration in the thermal management of the hardware.

scholarly journals Group-level analysis of induced electric field in deep brain regions by different TMS coils

2020 ◽  
Vol 65 (2) ◽  
pp. 025007 ◽  
Author(s):  
Jose Gomez-Tames ◽  
Atsushi Hamasaka ◽  
Akimasa Hirata ◽  
Ilkka Laakso ◽  
Mai Lu ◽  
...  
Keyword(s):  
Electric Field ◽  
Brain Regions ◽  
Group Level ◽  
Level Analysis ◽  
Deep Brain

scholarly journals Numerical Study on Electrode Design for Rodent Deep Brain Stimulation With Implantations Cranial to Targeted Nuclei

2021 ◽  
Vol 15 ◽  
Author(s):  
Konstantin Butenko ◽  
Rüdiger Köhling ◽  
Ursula van Rienen
Keyword(s):  
Deep Brain Stimulation ◽  
Electric Fields ◽  
Brain Stimulation ◽  
Numerical Study ◽  
Brain Regions ◽  
Electrode Design ◽  
Rodent Models ◽  
Neurological Damage ◽  
Direct Targeting ◽  
Deep Brain

The globus pallidus internus and the subthalamic nucleus are common targets for deep brain stimulation to alleviate symptoms of Parkinson's disease and dystonia. In the rodent models, however, their direct targeting is hindered by the relatively large dimensions of applied electrodes. To reduce the neurological damage, the electrodes are usually implanted cranial to the nuclei, thus exposing the non-targeted brain regions to large electric fields and, in turn, possible undesired stimulation effects. In this numerical study, we analyze the spread of the fields for the conventional electrodes and several modifications. As a result, we present a relatively simple electrode design that allows an efficient focalization of the stimulating field in the inferiorly located nuclei.

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