University of Twente, Drienerlolaan 5, 7522 NB Enschede, Netherlands.
J Neural Eng. 2017 Oct;14(5):056014. doi: 10.1088/1741-2552/aa7960. Epub 2017 Jun 20.
Trans-spinal direct current stimulation (tsDCS) is a potential new technique for the treatment of spinal cord injury (SCI). TsDCS aims to facilitate plastic changes in the neural pathways of the spinal cord with a positive effect on SCI recovery. To establish tsDCS as a possible treatment option for SCI, it is essential to gain a better understanding of its cause and effects. We seek to understand the acute effect of tsDCS, including the generated electric field (EF) and its polarization effect on the spinal circuits, to determine a cellular target. We further ask how these findings can be interpreted to explain published experimental results.
We use a realistic full body finite element volume conductor model to calculate the EF of a 2.5 mA direct current for three different electrode configurations. We apply the calculated electric field to realistic motoneuron models to investigate static changes in membrane resting potential. The results are combined with existing knowledge about the theoretical effect on a neuronal level and implemented into an existing lumbar spinal network model to simulate the resulting changes on a network level.
Across electrode configurations, the maximum EF inside the spinal cord ranged from 0.47 V m to 0.82 V m. Axon terminal polarization was identified to be the dominant cellular target. Also, differences in electrode placement have a large influence on axon terminal polarization. Comparison between the simulated acute effects and the electrophysiological long-term changes observed in human tsDCS studies suggest an inverse relationship between the two.
We provide methods and knowledge for better understanding the effects of tsDCS and serve as a basis for a more targeted and optimized application of tsDCS.
经颅直流电刺激(trans-spinal direct current stimulation, tsDCS)是一种治疗脊髓损伤(spinal cord injury, SCI)的潜在新技术。tsDCS 的目的是利用脊髓神经通路的可塑性变化，对 SCI 的恢复产生积极影响。为了将 tsDCS 确立为 SCI 的一种可能治疗选择，必须更好地了解其原因和效果。我们试图了解 tsDCS 的急性效应，包括产生的电场(electric field, EF)及其对脊髓回路的极化效应，以确定细胞靶点。我们进一步询问如何解释这些发现，以解释已发表的实验结果。
我们使用现实的全身有限元容积导体模型，为三种不同的电极配置计算 2.5 mA 直流电的 EF。我们将计算出的电场应用于现实的运动神经元模型，以研究膜静息电位的静态变化。结果与神经元水平理论效应的现有知识相结合，并被纳入现有的腰椎脊髓网络模型中，以模拟网络水平的相应变化。
在各种电极配置下，脊髓内的最大 EF 范围从 0.47 V/m 到 0.82 V/m。轴突末梢极化被确定为主要的细胞靶点。此外，电极放置位置的差异对轴突末梢极化有很大影响。模拟的急性效应与人类 tsDCS 研究中观察到的电生理长期变化之间的比较表明，两者之间存在反比关系。
我们提供了更好地理解 tsDCS 效应的方法和知识，并为更有针对性和优化的 tsDCS 应用提供了基础。
