Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales, Sydney, Australia.
School of Psychiatry, University of New South Wales, Sydney, Australia; Department of Psychiatry, St George Hospital, Sydney, Australia; Black Dog Institute, Sydney, Australia.
Brain Stimul. 2012 Jul;5(3):408-421. doi: 10.1016/j.brs.2011.07.004. Epub 2011 Aug 9.
Electroconvulsive therapy (ECT) is a highly effective treatment for severe depressive disorder. Efficacy and cognitive outcomes have been shown to depend on variations in electrode placement and other stimulus parameters, presumably because of differences in the pattern of neuronal activation. This latter effect, however, is poorly understood.
In this study, we present an anatomically accurate human head computational model to stimulate neuronal excitation during ECT, to better understand the effects of varying electrode placement and stimulus parameters.
Electric field and current density throughout the head, as well as direct neural activation within the brain, were computed using the finite element method. Regions representing passive volume conductors (skin, skull, cerebrospinal fluid) were extracellularly coupled to an excitable neural continuum region representing the brain. The skull was modeled with anistropic electrical conductivity.
Simulation results indicated that direct activation of the brain occurred immediately beneath the electrodes on the scalp, consistent with existing imaging studies. In addition, we found that the brainstem was also activated using a right unilateral electrode configuration. Simulation also demonstrated that a reduction in stimulus amplitude or pulse width led to a reduction in the spatial extent of brain activation.
The novel model described in this study was able to simulate direct excitation of the brain during ECT, was useful in characterizing differences in neuronal activation as electrode placement, pulse width, and amplitude were altered, and is proposed as a tool for further exploring the effects of variations in ECT stimulation approaches. Results from the simulations assist in understanding recently described clinical phenomena, in particular, the reduction in cognitive side effects with ultrabrief pulse width stimulation, and greater effects of the ECT stimulus on cardiovascular function with unilateral electrode placement.
电抽搐疗法（ECT）是一种治疗严重抑郁症的有效方法。疗效和认知结果取决于电极放置和其他刺激参数的变化，这可能是由于神经元激活模式的差异。然而，后一种效应理解得还很差。
在这项研究中，我们提出了一个解剖精确的人类头部计算模型，以刺激 ECT 期间的神经元兴奋，以更好地了解电极放置和刺激参数变化的影响。
使用有限元方法计算头部的电场和电流密度，以及大脑内的直接神经激活。代表被动容积导体（皮肤、颅骨、脑脊液）的区域与代表大脑的可兴奋神经连续体区域进行细胞外耦合。颅骨的电导率具有各向异性。
模拟结果表明，大脑的直接激活发生在头皮电极下方，与现有成像研究一致。此外，我们发现，使用右侧单侧电极配置也会激活脑干。模拟还表明，刺激幅度或脉冲宽度的降低会导致大脑激活的空间范围缩小。
本研究中描述的新模型能够模拟 ECT 期间大脑的直接兴奋，有助于描述电极放置、脉冲宽度和幅度改变时神经元激活的差异，并且可以作为进一步探索 ECT 刺激方法变化影响的工具。模拟结果有助于理解最近描述的临床现象，特别是超短脉冲宽度刺激对认知副作用的减少，以及单侧电极放置对心血管功能的 ECT 刺激作用更大。
