Lee Won Hee, Lisanby Sarah H, Laine Andrew F, Peterchev Angel V
IEEE Trans Biomed Eng. 2015 Sep;62(9):2095-105. doi: 10.1109/TBME.2015.2425406. Epub 2015 Apr 22.
To develop a pipeline for realistic head models of nonhuman primates (NHPs) for simulations of noninvasive brain stimulation, and use these models together with empirical threshold measurements to demonstrate that the models capture individual anatomical variability.
Based on structural MRI data, we created models of the electric field (E-field) induced by right unilateral (RUL) electroconvulsive therapy (ECT) in four rhesus macaques. Individual motor threshold (MT) was measured with transcranial electric stimulation (TES) administered through the RUL electrodes in the same subjects.
The interindividual anatomical differences resulted in 57% variation in median E-field strength in the brain at fixed stimulus current amplitude. Individualization of the stimulus current by MT reduced the E-field variation in the target motor area by 27%. There was significant correlation between the measured MT and the ratio of simulated electrode current and E-field strength (r(2) = 0.95, p = 0.026). Exploratory analysis revealed significant correlations of this ratio with anatomical parameters including of the superior electrode-to-cortex distance, vertex-to-cortex distance, and brain volume (r(2) > 0.96, p < 0.02). The neural activation threshold was estimated to be 0.45 ±0.07 V/cm for 0.2-ms stimulus pulse width.
These results suggest that our individual-specific NHP E-field models appropriately capture individual anatomical variability relevant to the dosing of TES/ECT. These findings are exploratory due to the small number of subjects.
This study can contribute insight in NHP studies of ECT and other brain stimulation interventions, help link the results to clinical studies, and ultimately lead to more rational brain stimulation dosing paradigms.
开发一种用于非人类灵长类动物（NHP）逼真头部模型的管道，以模拟无创脑刺激，并将这些模型与经验阈值测量结合使用，以证明模型能够捕捉个体解剖学变异性。
基于结构磁共振成像（MRI）数据，我们创建了四只恒河猴右侧单侧（RUL）电惊厥治疗（ECT）诱发的电场（E场）模型。在同一受试者中，通过RUL电极进行经颅电刺激（TES）测量个体运动阈值（MT）。
个体间的解剖差异导致在固定刺激电流幅度下，大脑中E场强度中位数有57%的变化。通过MT对刺激电流进行个体化处理，可使目标运动区域的E场变化减少27%。测量的MT与模拟电极电流和E场强度之比之间存在显著相关性（r(2)=0.95，p=0.026）。探索性分析显示，该比值与包括电极到皮层的上距离、顶点到皮层的距离和脑容量在内的解剖参数存在显著相关性（r(2)>0.96，p<0.02）。对于0.2毫秒的刺激脉冲宽度，神经激活阈值估计为0.45±0.07伏/厘米。
这些结果表明，我们的个体特异性NHP E场模型适当地捕捉了与TES/ECT给药相关的个体解剖学变异性。由于受试者数量较少，这些发现具有探索性。
本研究可为ECT和其他脑刺激干预的NHP研究提供见解，有助于将结果与临床研究联系起来，并最终导致更合理的脑刺激给药范式。
