Department of Neurology, Baystate Medical Center - UMass Medical School, Springfield, MA 01107, USA; Department of Biomedical Engineering and Institute of Applied Life Sciences, UMass Amherst, Amherst, MA 01003, USA.
Department of Neurology, Baystate Medical Center - UMass Medical School, Springfield, MA 01107, USA.
Neuroimage. 2021 Aug 15;237:118144. doi: 10.1016/j.neuroimage.2021.118144. Epub 2021 May 12.
We used three dose levels (Sham, 2 mA, and 4 mA) and two different electrode montages (unihemispheric and bihemispheric) to examine DOSE and MONTAGE effects on regional cerebral blood flow (rCBF) as a surrogate marker of neural activity, and on a finger sequence task, as a surrogate behavioral measure drawing on brain regions targeted by transcranial direct current stimulation (tDCS). We placed the anodal electrode over the right motor region (C4) while the cathodal or return electrode was placed either over a left supraorbital region (unihemispheric montage) or over the left motor region (C3 in the bihemispheric montage). Performance changes in the finger sequence task for both hands (left hand: p = 0.0026, and right hand: p = 0.0002) showed a linear tDCS dose response but no montage effect. rCBF in the right hemispheric perirolandic area increased with dose under the anodal electrode (p = 0.027). In contrast, in the perirolandic ROI in the left hemisphere, rCBF showed a trend to increase with dose (p = 0.053) and a significant effect of montage (p = 0.00004). The bihemispheric montage showed additional rCBF increases in frontomesial regions in the 4mA condition but not in the 2 mA condition. Furthermore, we found strong correlations between simulated current density in the left and right perirolandic region and improvements in the finger sequence task performance (FSP) for the contralateral hand. Our data support not only a strong direct tDCS dose effect for rCBF and FSP as surrogate measures of targeted brain regions but also indirect effects on rCBF in functionally connected regions (e.g., frontomesial regions), particularly in the higher dose condition and on FSP of the ipsilateral hand (to the anodal electrode). At a higher dose and irrespective of polarity, a wider network of sensorimotor regions is positively affected by tDCS.
我们使用了三个剂量水平（假刺激、2 mA 和 4 mA）和两种不同的电极排列方式（单半球和双半球），以检查剂量和电极排列方式对区域脑血流（rCBF）的影响，rCBF 作为神经活动的替代标志物，以及对手指序列任务的影响，该任务作为一种替代行为测量方法，利用经颅直流电刺激（tDCS）靶向的脑区。我们将阳极电极放置在右侧运动区（C4），而阴极或返回电极放置在左侧眶上区（单半球排列方式）或左侧运动区（C3 在双半球排列方式）。双手手指序列任务的表现变化（左手：p = 0.0026，右手：p = 0.0002）显示出线性 tDCS 剂量反应，但没有电极排列方式的影响。在阳极电极下，右侧半球旁运动区的 rCBF 随剂量增加而增加（p = 0.027）。相比之下，在左侧半球的旁运动区 ROI 中，rCBF 随剂量增加呈增加趋势（p = 0.053），且电极排列方式有显著影响（p = 0.00004）。双半球排列方式在 4 mA 条件下在前额内侧区域显示出额外的 rCBF 增加，但在 2 mA 条件下没有。此外，我们发现左侧和右侧旁运动区的模拟电流密度与对侧手手指序列任务表现（FSP）的改善之间存在强烈相关性。我们的数据不仅支持 rCBF 和 FSP 作为靶向脑区的替代测量指标的强烈直接 tDCS 剂量效应，还支持间接影响功能连接区域（例如，额内侧区域）的 rCBF，特别是在更高剂量条件下和同侧手的 FSP（到阳极电极）。在更高的剂量下，无论极性如何，更大的感觉运动区域网络都会受到 tDCS 的积极影响。
