High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS).
High-resolution computational modeling of the current flow in the outer ear during transcutaneous auricular Vagus Nerve Stimulation (taVNS).
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DOI：
10.1016/j.brs.2021.09.001
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发表时间：
2021-11
影响因子：
7.7
通讯作者：
Bikson M
中科院分区：
文献类型：
--
作者：
Kreisberg E;Esmaeilpour Z;Adair D;Khadka N;Datta A;Badran BW;Bremner JD;Bikson M
经皮耳迷走神经刺激（taVNS）向耳朵施加低强度电流，目的是激活迷走神经的耳分支。施加到耳朵的刺激的灵敏度和选择性取决于由给定电极蒙太奇（大小和放置）产生的电流模式。我们比较了不同的电极设计taVNS考虑预测的峰值电场（灵敏度）和它们的空间分布（选择性）。基于优化的高分辨率（0.47 mm）T1和T2加权MRI，我们开发了左耳和周围头部组织（包括脑、CSF/脑膜、颅骨、肌肉、血管、脂肪、软骨和皮肤）的解剖模型。根据不同的神经密度，将耳朵进一步分割为6个感兴趣区域（ROI）：耳甲腔、耳甲桥、耳轮、耳屏、对耳屏和耳垂。复制了一系列taVNS电极蒙太奇，包括耳屏、耳甲桥、耳垂、耳甲腔和耳轮上的不同电极尺寸和位置。假设激活阈值为6.15 V/m、12.3 V/m或24.6 V/m，使用有限元法（FEM）预测在1 mA或2 mA taVNS下每个导联的耳（从浅表皮肤到软骨）电场。最后，考虑到每个ROI，我们计算了每个蒙太奇的灵敏度和选择性。通过耳朵的电流模式对电极导联具有高度特异性。电场在电极正下方的耳朵区域处最大，并且对于给定的总电流，随着电极尺寸的减小而增大。根据施加的电流和神经阈值，激活也可能发生在多个前表面电极之间的区域中。每个考虑的蒙太奇都是针对一个或两个感兴趣区域的选择性。例如，跨耳屏的电极限制了对耳屏的显著电场。通过耳垂的刺激将显著的电场限制在耳垂和对耳屏。由于这种相对选择性，在实验研究中使用对照耳蒙太奇支持靶向测试。相对靶向在激活阈值和组织性质的假设中是稳健的。计算模型提供了关于电极形状和放置细节如何影响灵敏度（需要多少电流）和选择性（空间分布）的额外见解，从而支持对现有方法的分析和对新设备的优化。我们的研究结果表明，taVNS电流模式和相对目标是强大的个体，虽然（方差）轴突形态没有表示。
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). We compare different electrodes designs for taVNS considering both the predicted peak electric fields (sensitivity) and their spatial distribution (selectivity). 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. 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. 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.
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影响因子：
3
作者：
Charvet LE;Kasschau M;Datta A;Knotkova H;Stevens MC;Alonzo A;Loo C;Krull KR;Bikson M
通讯作者：
Bikson M
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通讯作者：
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通讯作者：
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