Optimized multi-electrode stimulation increases focality and intensity at target
Optimized multi-electrode stimulation increases focality and intensity at target
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DOI：
10.1088/1741-2560/8/4/046011
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发表时间：
2011-08-01
影响因子：
4
通讯作者：
Parra, Lucas C.
中科院分区：
文献类型：
--
作者：
Dmochowski, Jacek P.;Datta, Abhishek;Parra, Lucas C.
经颅直流电刺激（tDCS）提供了一种非侵入性工具，通过放置在头皮上的电极输送电流来引起神经调节。目前的临床范例使用两个相对较大的电极来通过头部注入电流，从而产生广泛分布在大脑的大区域上的电场。在本文中，我们提出了一种方法，使用多个小电极（即1.2厘米直径），并系统地优化所施加的电流，以实现有效的和有针对性的刺激，同时确保刺激的安全性。我们发现了一个基本的权衡可实现的强度（在目标）和焦点，算法来优化这两个措施。当与大的垫电极（这里近似为一组覆盖25 cm（2）的小电极）相比时，所提出的方法实现了使用相同的总电流在皮质目标处同时表现出更大的聚焦性（80%的改善）和更高的目标强度（98%的改善）的电场。这些改进说明了最佳电极配置对所需电场方向和最大总电流（出于安全考虑）的先前未认识到且非平凡的依赖性。类似地，通过利用脑解剖结构的特异质细节，优化方法显著改进了使用小电极的先前未优化方法。该分析还揭示了传统双极导联的最佳使用：最大强度的切向场是通过沿所需场的方向放置在距目标沿着相当远的距离处的两个电极获得的;当需要径向场时，最大强度配置由直接放置在目标上方的电极和远距离返回电极组成。总而言之，如果临床医生可以定义目标位置和刺激方向，则与先前的解决方案相比，所提出的技术在聚焦性和强度方面都是上级的，因此预期将转化为改善的患者安全性和增加的临床疗效。
Transcranial direct current stimulation (tDCS) provides a non-invasive tool to elicit neuromodulation by delivering current through electrodes placed on the scalp. The present clinical paradigm uses two relatively large electrodes to inject current through the head resulting in electric fields that are broadly distributed over large regions of the brain. In this paper, we present a method that uses multiple small electrodes (i.e. 1.2 cm diameter) and systematically optimize the applied currents to achieve effective and targeted stimulation while ensuring safety of stimulation. We found a fundamental trade-off between achievable intensity (at the target) and focality, and algorithms to optimize both measures are presented. When compared with large pad-electrodes (approximated here by a set of small electrodes covering 25 cm(2)), the proposed approach achieves electric fields which exhibit simultaneously greater focality (80% improvement) and higher target intensity (98% improvement) at cortical targets using the same total current applied. These improvements illustrate the previously unrecognized and non-trivial dependence of the optimal electrode configuration on the desired electric field orientation and the maximum total current (due to safety). Similarly, by exploiting idiosyncratic details of brain anatomy, the optimization approach significantly improves upon prior un-optimized approaches using small electrodes. The analysis also reveals the optimal use of conventional bipolar montages: maximally intense tangential fields are attained with the two electrodes placed at a considerable distance from the target along the direction of the desired field; when radial fields are desired, the maximum-intensity configuration consists of an electrode placed directly over the target with a distant return electrode. To summarize, if a target location and stimulation orientation can be defined by the clinician, then the proposed technique is superior in terms of both focality and intensity as compared to previous solutions and is thus expected to translate into improved patient safety and increased clinical efficacy.