Transcranial direct current stimulation (tDCS) is an easy to use, noninvasive brain stimulation technique that gained prominence for its potential in cognitive rehabilitation. Electroencephalography (EEG), which records electrical brain activity with a high temporal resolution, is well suited to quantify tDCS-induced neuromodulation in humans. However, most studies relying on scalp EEG recordings or event-related potentials showed low reliability and only indirect correlations. Here, we combined intracranial EEG (iEEG) recordings with a sham-controlled tDCS experiment during fast periodic visual stimulation. Anodal (+2 mA) tDCS was applied over the right occipito-temporal cortex for 20 min using two small ring high-definition electrodes. Through the analysis of iEEG signals of 947 intracerebral contacts in 11 drug-resistant epileptic patients, we quantified the neuromodulation of iEEG cognitive evoked responses during (P2 phase) and after (P3 phase) tDCS by comparison to a control phase before tDCS (P1 phase). Significant neuromodulations of face-selective iEEG activity in anterior & posterior temporal lobe and in the occipital lobe were found, with amplitude increases of 3% and 4%, 16% and 13%, and 36% and 33%, during and after tDCS, respectively. Interestingly, despite a unique tDCS session, the face-selective neuromodulation in the right visual occipito-temporal cortex remained significant ( P = 0.015) after tDCS (P3 vs. P1). This iEEG study demonstrates that using low intensity tDCS and small ring electrodes can induce significant electrophysiological effects on a selective cognitive function in humans.

中文翻译：

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经颅直流电刺激神经调节人类颅内认知诱发电量活动

经颅直流电刺激 （tDCS） 是一种易于使用的无创脑刺激技术，因其在认知康复方面的潜力而备受关注。脑电图 （EEG） 以高时间分辨率记录脑电活动，非常适合量化 tDCS 诱导的人类神经调控。然而，大多数依赖于头皮脑电图记录或事件相关电位的研究显示可靠性低，并且只有间接相关性。在这里，我们将颅内脑电图 （iEEG） 记录与快速周期性视觉刺激期间的假对照 tDCS 实验相结合。使用两个小环形高清电极将阳极 （+2 mA） tDCS 应用于右侧枕颞叶皮层 20 分钟。通过分析 11 名耐药癫痫患者 947 名脑内接触者的 iEEG 信号，我们量化了 tDCS 期间 （P2 期） 和之后 （P3 期） iEEG 认知诱发反应的神经调控与 tDCS 之前的对照阶段 （P1 期）。在前后颞叶和枕叶中发现了面部选择性 iEEG 活动的显著神经调节，幅度分别增加了 3%和 4%，16%和 13%，以及 36%和 33%，在 tDCS 期间和之后。有趣的是，尽管进行了独特的 tDCS 会话，但在 tDCS 后，右侧视觉枕颞叶皮层的面部选择性神经调控仍然显着 （P = 0.015） （P3 vs. P1）。这项 iEEG 研究表明，使用低强度 tDCS 和小环形电极可以对人类的选择性认知功能产生显着的电生理效应。