Department of Radiology, the First Affiliated Hospital of USTC, Hefei National Research Center for Physical Sciences at the Microscale and School of Life Science, Division of Life Science and Medicine, University of Science & Technology of China, Hefei, China.
Department of Social and Behavioural Sciences, City University of Hong Kong, Hong Kong, People's Republic of China.
PLoS Biol. 2023 Feb 13;21(2):e3001999. doi: 10.1371/journal.pbio.3001999. eCollection 2023 Feb.
Although previous studies have reported correlations between alpha oscillations and the "retention" subprocess of working memory (WM), causal evidence has been limited in human neuroscience due to the lack of delicate modulation of human brain oscillations. Conventional transcranial alternating current stimulation (tACS) is not suitable for demonstrating the causal evidence for parietal alpha oscillations in WM retention because of its inability to modulate brain oscillations within a short period (i.e., the retention subprocess). Here, we developed an online phase-corrected tACS system capable of precisely correcting for the phase differences between tACS and concurrent endogenous oscillations. This system permits the modulation of brain oscillations at the target stimulation frequency within a short stimulation period and is here applied to empirically demonstrate that parietal alpha oscillations causally relate to WM retention. Our experimental design included both in-phase and anti-phase alpha-tACS applied to participants during the retention subprocess of a modified Sternberg paradigm. Compared to in-phase alpha-tACS, anti-phase alpha-tACS decreased both WM performance and alpha activity. These findings strongly support a causal link between alpha oscillations and WM retention and illustrate the broad application prospects of phase-corrected tACS.
虽然先前的研究报告了 alpha 振荡与工作记忆 (WM) 的“保持”子过程之间的相关性，但由于缺乏对人类大脑振荡的精细调节，人类神经科学中的因果证据一直有限。由于传统的经颅交流电刺激 (tACS) 无法在短时间内调节大脑振荡（即保持子过程），因此不适合证明 WM 保持中顶叶 alpha 振荡的因果证据。在这里，我们开发了一种在线相位校正 tACS 系统，能够精确校正 tACS 和同时发生的内源性振荡之间的相位差。该系统允许在短刺激期间以目标刺激频率调制大脑振荡，并在此应用于实证证明顶叶 alpha 振荡与 WM 保持有因果关系。我们的实验设计包括在修改后的 Sternberg 范式的保持子过程中向参与者施加同相和反相 alpha-tACS。与同相 alpha-tACS 相比，反相 alpha-tACS 降低了 WM 性能和 alpha 活动。这些发现强烈支持 alpha 振荡与 WM 保持之间的因果关系，并说明了相位校正 tACS 的广泛应用前景。
