OP 11. Optimized tDCS electrode configurations for five targets determined via an inverse FE modeling approach
OP 11. Optimized tDCS electrode configurations for five targets determined via an inverse FE modeling approach
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OP 11. 通过逆有限元建模方法确定的五个目标的优化 tDCS 电极配置
DOI：
10.1016/j.clinph.2013.04.078
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发表时间：
2013
影响因子：
4.7
通讯作者：
T. Oostendorp
中科院分区：
文献类型：
--
作者：
S. Rampersad;Dick F. Stegeman;Dick F. Stegeman;T. Oostendorp
引言经颅直流电刺激（tDCS）已显示出改善健康受试者和患有各种神经病理学的患者的脑功能的潜力。不幸的是，tDCS的效果太小，寿命太短，无法用作临床治疗。增加tDCS的效应大小可能通过更好地在方向和幅度上瞄准电流来实现。体积传导建模已经表明，具有最高电场强度的区域并不像通常假设的那样位于电极下方（Datta等人，2009年）。已经公开了针对点电极和环电极的优化尝试（[Im等人，2008]，[Dmochowski等人，2011]），但不适用于大多数实验室中使用的方形贴片。为了找到这些电极，配置，导致在目标区域的最大刺激，我们提出了一个逆建模approach.ObjectivesWe模拟tDCS为10000配置，并确定这些导致最佳电场，无论是在强度和方向，在五个最目标的位置在tDCS研究：运动皮层（M1）、背外侧前额叶皮层、额下回、枕叶皮层和小脑。该模型包含超过400万个元素和11种组织类型。通过包括海绵层和颅骨孔，特别关注颅骨，这是tDCS电流的主要屏障。脑各向异性由DTI测量得出，在皮肤表面上放置由标准10-10 EEG系统和脸颊和颈部的额外点组成的89个点的网格。对于2个点的每个组合，我们将5 × 5 cm电极贴片放置在模型上，以两个点为中心，并模拟1 mA tDCS。在每个目标，我们放置在大脑中的圆柱形体积和选择的配置导致最高的平均场强或最佳方向的目标volum.ResultsFor所有目标，优化的配置不包括常用的配置。通常，在接近垂直于标准配置的配置中发现最高场强。优化的基础上，无论是强度或方向的字段导致完全不同的configuration.ConclusionThe优化的配置，发现在这项研究中表明，改进的结果tDCS可以预期。我们通过观察磁场的强度或方向发现了不同的优化配置。通过实验比较这些优化配置不仅可以验证我们的建模方法，还可以提供有关tDCS背后机制的有价值的信息。该方法可用于优化任何目标位置的刺激。
IntroductionTranscranial direct current stimulation (tDCS) has shown potential in improving brain function in both healthy subjects and patients suffering from a wide range of neuropathologies. Unfortunately, the effects are too small and short-lived for tDCS to be used as a clinical therapy. Increasing the effect size of tDCS could possibly be achieved by better targeting the current, both in direction and amplitude. Volume conduction modeling has shown that the areas with the highest electric fields strengths do not, as is often assumed, lie beneath the electrodes (Datta et al., 2009). Attempts at optimization have been published for point and ring electrodes ([Im et al., 2008], [Dmochowski et al., 2011]), but not for the square patches used in most labs. In order to find for these electrodes, configurations that do result in maximum stimulation at the target area, we propose an inverse modeling approach.ObjectivesWe simulate tDCS for ∼7000 configurations and determine which of these lead to optimal electric fields, both in strength and direction, at the five most target locations in tDCS research: motor cortex (M1), dorsolateral prefrontal cortex, inferior frontal gyrus, occipital cortex and cerebellum.MethodsA detailed finite element (FE) head model was made by automatic segmentation of MR images aided by manual corrections. The model contains over 4 million elements and 11 tissue types. Special attention was given to the skull, the main barrier for the tDCS current, by including the spongiosa layer and skull holes. Brain anisotropy was derived from DTI measurements.On the skin surface, a grid of 89 points was placed consisting of the standard 10–10 EEG system and extra points on the cheeks and neck. For each combination of 2 points, we placed 5 × 5 cm electrode patches onto the model, centred on the two points, and simulated 1 mA tDCS. At each target, we placed a cylindrical volume in the brain and selected the configurations leading to highest mean field strength or optimal direction in the target volume.ResultsFor all targets, the optimized configurations did not include the commonly used configurations. Often, highest field strengths were found in configurations that are near-perpendicular to the standard configurations. Optimization based on either strength or direction of the field lead to completely different configurations.ConclusionThe optimized configurations found in this study suggest that improved results of tDCS can be expected. We found different optimized configurations by looking at either strength or direction of the field. Comparing these optimized configurations experimentally will not only verify our modeling approach, but also provide valuable information on the mechanisms behind tDCS. This approach can be used to optimize stimulation for any target location.