Transcranial direct current stimulation (tDCS) can improve cognitive function. However, it is not clear how high-definition tDCS (HD-tDCS) regulates the cognitive function and its neural mechanism, especially in individuals with mild cognitive impairment (MCI). This study aimed to examine whether HD-tDCS can modulate cognitive function in individuals with MCI and to determine whether the potential variety is related to spontaneous brain activity changes recorded by resting-state functional magnetic resonance imaging (rs-fMRI). Forty-three individuals with MCI were randomly assigned to receive either 10 HD-tDCS sessions or 10 sham sessions to the left dorsolateral prefrontal cortex (L-DLPFC). The fractional amplitude of low-frequency fluctuation (fALFF) and the regional homogeneity (ReHo) was computed using rs-fMRI data from all participants. The results showed that the fALFF and ReHo values changed in multiple areas following HD-tDCS. Brain regions with significant decreases in fALFF values include the Insula R, Precuneus R, Thalamus L, and Parietal Sup R, while the Temporal Inf R, Fusiform L, Occipital Sup L, Calcarine R, and Angular R showed significantly increased in their fALFF values. The brain regions with significant increases in ReHo values include the Temporal Inf R, Putamen L, Frontal Mid L, Precentral R, Frontal Sup Medial L, Frontal Sup R, and Precentral L. We found that HD-tDCS can alter the intensity and synchrony of brain activity, and our results indicate that fALFF and ReHo analysis are sensitive indicators for the detection of HD-tDCS during spontaneous brain activity. Interestingly, HD-tDCS increases the ReHo values of multiple brain regions, which may be related to the underlying mechanism of its clinical effects, these may also be related to a potential compensation mechanism involving the mobilization of more regions to complete a function following a functional decline.

中文翻译：

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在轻度认知障碍患者的左背外侧前额叶皮层上重复阳极高清经颅直流电刺激增加了多个大脑区域的区域同质性。

经颅直流电刺激（tDCS）可以改善认知功能。然而，目前尚不清楚高清tDCS（HD-tDCS）如何调节认知功能及其神经机制，尤其是在轻度认知障碍（MCI）个体中。本研究旨在检查 HD-tDCS 是否可以调节 MCI 个体的认知功能，并确定潜在的变化是否与静息状态功能磁共振成像 (rs-fMRI) 记录的自发大脑活动变化有关。43 名患有 MCI 的人被随机分配到左侧背外侧前额叶皮层 (L-DLPFC) 接受 10 次 HD-tDCS 会话或 10 次假手术。使用来自所有参与者的 rs-fMRI 数据计算低频波动的分数幅度 (fALFF) 和区域同质性 (ReHo)。结果表明，在 HD-tDCS 之后，fALFF 和 ReHo 值在多个区域发生了变化。fALFF 值显着降低的大脑区域包括 Insula R、Precuneus R、Thalamus L 和顶叶 Sup R，而颞 Inf R、梭状 L、枕骨 Sup L、Calcarine R 和 Angular R 的 fALFF 值显着增加. ReHo 值显着增加的大脑区域包括 Temporal Inf R、Putamen L、Frontal Mid L、Precentral R、Frontal Sup 内侧 L、Frontal Sup R 和 Precentral L。我们发现 HD-tDCS 可以改变强度和同步性大脑活动，我们的结果表明 fALFF 和 ReHo 分析是检测自发大脑活动期间 HD-tDCS 的敏感指标。有趣的是，HD-tDCS 增加了多个大脑区域的 ReHo 值，