Department of Clinical and Health Psychology, Department of Neuroscience, Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
Department of Clinical and Health Psychology, Department of Neuroscience, Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
Brain Stimul. 2019 Mar-Apr;12(2):267-274. doi: 10.1016/j.brs.2018.10.016. Epub 2018 Oct 28.
Inaccurate electrode placement and electrode drift during a transcranial electrical stimulation (tES) session have been shown to alter predicted field distributions in the brain and thus may contribute to a large variation in tES study outcomes. Currently, there is no objective and independent measure to quantify electrode placement accuracy/drift in tES clinical studies.
OBJECTIVE/HYPOTHESIS: We proposed and tested novel methods to quantify accurate and consistent electrode placements in tES using models generated from a 3D scanner.
Accurate electrode placements were quantified as Discrepancy in eight tES participants by comparing landmark distances of physical electrode locations F3/F4 to their model counterparts. Distances in models were computed using curve and linear based methods. Variability of landmark locations in a single subject was computed for multiple stimulation sessions to determine consistent electrode placements across four experimenters.
We obtained an average of 0.4 cm in Discrepancy, which was within the placement accuracy/drift threshold (1 cm) for conventional tES electrodes (∼35 cm) to achieve reliable tES sessions suggested in the literature. Averaged Variability was 5.2%, with F4 electrode location as the least consistent placement.
These methods provide objective feedback for experimenters on their performance in placing tES electrodes. Applications of these methods can be used to monitor electrode locations in tES studies of a larger cohort using F3/F4 montage and other conventional electrode arrangements. Future studies may include co-registering the landmark locations with imaging-derived head models to quantify the effects of electrode accuracy/drift on predicted field distributions in the brain.
在经颅电刺激（tES）过程中，电极放置不准确和电极漂移已被证明会改变大脑中预测的场分布，因此可能导致 tES 研究结果的很大差异。目前，在 tES 临床研究中，没有客观和独立的方法来量化电极放置的准确性/漂移。
目的/假设：我们提出并测试了使用 3D 扫描仪生成的模型来量化 tES 中准确和一致的电极放置的新方法。
在 8 名 tES 参与者中，通过将物理电极位置 F3/F4 的地标距离与模型对应物进行比较，来量化准确的电极放置。模型中的距离使用曲线和线性方法计算。在多个刺激会话中计算单个受试者地标位置的可变性，以确定四个实验者之间一致的电极放置。
我们获得了 0.4cm 的平均差异，这在传统 tES 电极（约 35cm）的放置准确性/漂移阈值（1cm）范围内，以实现文献中建议的可靠 tES 会话。平均可变性为 5.2%，其中 F4 电极位置的放置最不一致。
这些方法为实验者提供了关于他们放置 tES 电极性能的客观反馈。这些方法的应用可用于使用 F3/F4 导联和其他常规电极排列监测更大队列的 tES 研究中的电极位置。未来的研究可能包括将地标位置与成像衍生的头部模型配准，以量化电极准确性/漂移对大脑中预测场分布的影响。
