Kim Seong-Eun, Kim Hyun-Seok, Kwak Youngchul, Ahn Min-Hee, Choi Kyung Mook, Min Byoung-Kyong
Department of Applied Artificial Intelligence, Seoul National University of Science and Technology, Seoul, South Korea.
Biomedical Engineering Research Center, Asan Medical Center, Seoul, South Korea.
Front Neurosci. 2022 Oct 3;16:1013691. doi: 10.3389/fnins.2022.1013691. eCollection 2022.
Transcranial current stimulation is a neuromodulation technique used to modulate brain oscillations and, in turn, to enhance human cognitive function in a non-invasive manner. This study investigated whether cross-frequency coupled transcranial alternating current stimulation (CFC-tACS) improved working memory performance. Participants in both the tACS-treated and sham groups were instructed to perform a modified Sternberg task, where a combination of letters and digits was presented. Theta-phase/high-gamma-amplitude CFC-tACS was administered over electrode F3 and its four surrounding return electrodes (Fp1, Fz, F7, and C3) for 20 min. To identify neurophysiological correlates for the tACS-mediated enhancement of working memory performance, we analyzed EEG alpha and theta power, cross-frequency coupling, functional connectivity, and nodal efficiency during the retention period of the working memory task. We observed significantly reduced reaction times in the tACS-treated group, with suppressed treatment-mediated differences in frontal alpha power and unidirectional Fz-delta-phase to Oz-high-gamma-amplitude modulation during the second half of the retention period when network analyses revealed tACS-mediated fronto-occipital dissociative neurodynamics between alpha suppression and delta/theta enhancement. These findings indicate that tACS modulated top-down control and functional connectivity across the fronto-occipital regions, resulting in improved working memory performance. Our observations are indicative of the feasibility of enhancing cognitive performance by the CFC-formed tACS.
经颅电流刺激是一种神经调节技术，用于调节脑振荡，进而以非侵入性方式增强人类认知功能。本研究调查了交叉频率耦合经颅交流电刺激（CFC-tACS）是否能改善工作记忆表现。tACS治疗组和假刺激组的参与者都被要求执行一项改良的斯特恩伯格任务，任务中会呈现字母和数字的组合。在电极F3及其周围四个返回电极（Fp1、Fz、F7和C3）上施加θ相位/高γ振幅CFC-tACS，持续20分钟。为了确定tACS介导的工作记忆表现增强的神经生理学相关因素，我们在工作记忆任务的保持期分析了脑电图的α和θ功率、交叉频率耦合、功能连接和节点效率。我们观察到tACS治疗组的反应时间显著缩短，在保持期后半段，额叶α功率的治疗介导差异受到抑制，并且在网络分析显示tACS介导的α抑制和δ/θ增强之间的额枕解离神经动力学时，存在从Fzδ相位到Oz高γ振幅的单向调制。这些发现表明，tACS调节了额枕区域的自上而下控制和功能连接，从而改善了工作记忆表现。我们的观察结果表明，通过CFC形成的tACS增强认知表现是可行的。
