Lee Won Hee, Kennedy Nigel I, Bikson Marom, Frangou Sophia
Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, United States.
Department of Biomedical Engineering, The City College of New York, City University of New York, New York, NY, United States.
Front Psychiatry. 2018 Feb 22;9:48. doi: 10.3389/fpsyt.2018.00048. eCollection 2018.
We use auditory verbal hallucinations (AVH) to illustrate the challenges in defining and assessing target engagement in the context of transcranial direct current stimulation (tDCS) for psychiatric disorders. We defined the target network as the cluster of regions of interest (ROIs) that are consistently implicated in AVH based on the conjunction of multimodal meta-analytic neuroimaging data. These were prescribed in the New York Head (a population derived model) and head models of four single individuals. We appraised two potential measures of target engagement, tDCS-induced peak electric field strength and tDCS-modulated volume defined as the percentage of the volume of the AVH network exposed to electric field magnitude stronger than the postulated threshold for neuronal excitability. We examined a left unilateral (LUL) montage targeting the prefrontal cortex (PFC) and temporoparietal junction (TPJ), a bilateral (BL) prefrontal montage, and a 2 × 1 montage targeting the left PFC and the TPJ bilaterally. Using computational modeling, we estimated the peak electric field strength and modulated volume induced by each montage for current amplitudes ranging 1-4 mA. We found that the LUL montage was inferior to both other montages in terms of peak electric field strength in right-sided AVH-ROIs. The BL montage was inferior to both other montages in terms of modulated volume of the left-sided AVH-ROIs. As the modulated volume is non-linear, its variability between montages reduced for current amplitudes above 3 mA. These findings illustrate how computational target engagement for tDCS can be tailored to specific networks and provide a principled approach for future study design.
我们使用听觉言语幻觉（AVH）来说明在经颅直流电刺激（tDCS）治疗精神疾病的背景下定义和评估靶点参与度所面临的挑战。我们将目标网络定义为基于多模态元分析神经影像数据的联合，始终与AVH相关的感兴趣区域（ROI）集群。这些区域在纽约头部模型（一种基于人群的模型）和四个个体的头部模型中被规定。我们评估了两种潜在的靶点参与度测量方法，即tDCS诱导的峰值电场强度和tDCS调制体积，tDCS调制体积定义为暴露于比假定的神经元兴奋性阈值更强的电场强度下的AVH网络体积的百分比。我们研究了针对前额叶皮质（PFC）和颞顶叶交界处（TPJ）的左单侧（LUL）电极片、双侧（BL）前额叶电极片以及双侧针对左PFC和TPJ的2×1电极片。使用计算模型，我们估计了每个电极片在1 - 4 mA电流幅度下诱导的峰值电场强度和调制体积。我们发现，在右侧AVH - ROI的峰值电场强度方面，LUL电极片不如其他两种电极片。在左侧AVH - ROI的调制体积方面，BL电极片不如其他两种电极片。由于调制体积是非线性的，对于高于3 mA的电流幅度，其在不同电极片之间的变异性降低。这些发现说明了如何针对tDCS的计算靶点参与度进行特定网络的定制，并为未来的研究设计提供了一种有原则的方法。
