High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)

Background: Transcutaneous auricular Vagus Nerve Stimulation (taVNS) applies low-intensity electrical current to the ear with the intention of activating the auricular branch of the Vagus nerve. The sensitivity and selectivity of stimulation applied to the ear depends on current flow pattern produce...

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Autores principales: Erica Kreisberg, Zeinab Esmaeilpour, Devin Adair, Niranjan Khadka, Abhishek Datta, Bashar W. Badran, J. Douglas Bremner, Marom Bikson
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Publicado: Elsevier 2021
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spelling oai:doaj.org-article:7d2c4e3d19f24e35b8b02c778cfef7002021-11-20T04:58:23ZHigh-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)1935-861X10.1016/j.brs.2021.09.001https://doaj.org/article/7d2c4e3d19f24e35b8b02c778cfef7002021-11-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S1935861X21002278https://doaj.org/toc/1935-861XBackground: Transcutaneous auricular Vagus Nerve Stimulation (taVNS) applies low-intensity electrical current to the ear with the intention of activating the auricular branch of the Vagus nerve. The sensitivity and selectivity of stimulation applied to the ear depends on current flow pattern produced by a given electrode montage (size and placement). Objective: We compare different electrodes designs for taVNS considering both the predicted peak electric fields (sensitivity) and their spatial distribution (selectivity). Methods: Based on optimized high-resolution (0.47 mm) T1 and T2 weighted MRI, we developed an anatomical model of the left ear and the surrounding head tissues including brain, CSF/meninges, skull, muscle, blood vessels, fat, cartilage, and skin. The ear was further segmented into 6 regions of interest (ROI) based on various nerve densities: cavum concha, cymba concha, crus of helix, tragus, antitragus, and earlobe. A range of taVNS electrode montages were reproduced spanning varied electrodes sizes and placements over the tragus, cymba concha, earlobe, cavum concha, and crus of helix. Electric field across the ear (from superficial skin to cartilage) for each montage at 1 mA or 2 mA taVNS, assuming an activation threshold of 6.15 V/m, 12.3 V/m or 24.6 V/m was predicted using a Finite element method (FEM). Finally, considering every ROI, we calculated the sensitivity and selectivity of each montage. Results: Current flow patterns through the ear were highly specific to the electrode montage. Electric field was maximal at the ear regions directly under the electrodes, and for a given total current, increases with decreasing electrode size. Depending on the applied current and nerves threshold, activation may also occur in the regions between multiple anterior surface electrodes. Each considered montage was selective for one or two regions of interest. For example, electrodes across the tragus restricted significant electric field to the tragus. Stimulation across the earlobe restricted significant electric field to the earlobe and the antitragus. Because of this relative selectivity, use of control ear montages in experimental studies, support testing of targeting. Relative targeting was robust across assumptions of activation threshold and tissue properties. Discussion: Computational models provide additional insight on how details in electrode shape and placement impact sensitivity (how much current is needed) and selectivity (spatial distribution), thereby supporting analysis of existing approaches and optimization of new devices. Our result suggest taVNS current patterns and relative target are robust across individuals, though (variance in) axon morphology was not represented.Erica KreisbergZeinab EsmaeilpourDevin AdairNiranjan KhadkaAbhishek DattaBashar W. BadranJ. Douglas BremnerMarom BiksonElsevierarticleNon-invasive brain stimulationTranscutaneous auricular vagus nerve stimulationAuricular branch of the vagus nerveComputational modellingFinite element method modelsCurrent flow modelsNeurosciences. Biological psychiatry. NeuropsychiatryRC321-571ENBrain Stimulation, Vol 14, Iss 6, Pp 1419-1430 (2021)
institution DOAJ
collection DOAJ
language EN
topic Non-invasive brain stimulation
Transcutaneous auricular vagus nerve stimulation
Auricular branch of the vagus nerve
Computational modelling
Finite element method models
Current flow models
Neurosciences. Biological psychiatry. Neuropsychiatry
RC321-571
spellingShingle Non-invasive brain stimulation
Transcutaneous auricular vagus nerve stimulation
Auricular branch of the vagus nerve
Computational modelling
Finite element method models
Current flow models
Neurosciences. Biological psychiatry. Neuropsychiatry
RC321-571
Erica Kreisberg
Zeinab Esmaeilpour
Devin Adair
Niranjan Khadka
Abhishek Datta
Bashar W. Badran
J. Douglas Bremner
Marom Bikson
High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
description Background: Transcutaneous auricular Vagus Nerve Stimulation (taVNS) applies low-intensity electrical current to the ear with the intention of activating the auricular branch of the Vagus nerve. The sensitivity and selectivity of stimulation applied to the ear depends on current flow pattern produced by a given electrode montage (size and placement). Objective: We compare different electrodes designs for taVNS considering both the predicted peak electric fields (sensitivity) and their spatial distribution (selectivity). Methods: Based on optimized high-resolution (0.47 mm) T1 and T2 weighted MRI, we developed an anatomical model of the left ear and the surrounding head tissues including brain, CSF/meninges, skull, muscle, blood vessels, fat, cartilage, and skin. The ear was further segmented into 6 regions of interest (ROI) based on various nerve densities: cavum concha, cymba concha, crus of helix, tragus, antitragus, and earlobe. A range of taVNS electrode montages were reproduced spanning varied electrodes sizes and placements over the tragus, cymba concha, earlobe, cavum concha, and crus of helix. Electric field across the ear (from superficial skin to cartilage) for each montage at 1 mA or 2 mA taVNS, assuming an activation threshold of 6.15 V/m, 12.3 V/m or 24.6 V/m was predicted using a Finite element method (FEM). Finally, considering every ROI, we calculated the sensitivity and selectivity of each montage. Results: Current flow patterns through the ear were highly specific to the electrode montage. Electric field was maximal at the ear regions directly under the electrodes, and for a given total current, increases with decreasing electrode size. Depending on the applied current and nerves threshold, activation may also occur in the regions between multiple anterior surface electrodes. Each considered montage was selective for one or two regions of interest. For example, electrodes across the tragus restricted significant electric field to the tragus. Stimulation across the earlobe restricted significant electric field to the earlobe and the antitragus. Because of this relative selectivity, use of control ear montages in experimental studies, support testing of targeting. Relative targeting was robust across assumptions of activation threshold and tissue properties. Discussion: Computational models provide additional insight on how details in electrode shape and placement impact sensitivity (how much current is needed) and selectivity (spatial distribution), thereby supporting analysis of existing approaches and optimization of new devices. Our result suggest taVNS current patterns and relative target are robust across individuals, though (variance in) axon morphology was not represented.
format article
author Erica Kreisberg
Zeinab Esmaeilpour
Devin Adair
Niranjan Khadka
Abhishek Datta
Bashar W. Badran
J. Douglas Bremner
Marom Bikson
author_facet Erica Kreisberg
Zeinab Esmaeilpour
Devin Adair
Niranjan Khadka
Abhishek Datta
Bashar W. Badran
J. Douglas Bremner
Marom Bikson
author_sort Erica Kreisberg
title High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
title_short High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
title_full High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
title_fullStr High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
title_full_unstemmed High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS)
title_sort high-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular vagus nerve stimulation (tavns)
publisher Elsevier
publishDate 2021
url https://doaj.org/article/7d2c4e3d19f24e35b8b02c778cfef700
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