Alpha Oscillatory Activity Causally Linked to Working Memory Retention: Insights from Online Phase-corrected Closed-loop Transcranial Alternating Current Stimulation (tACS)

Abstract

Although previous studies have reported correlations between alpha oscillations and the "retention" sub-process of working memory (WM), no direct causal evidence has been established in human neuroscience. Here, we developed an online phase-locking closed-loop transcranial alternating current stimulation (tACS) system capable of precisely controlling the phase difference between tACS and concurrent endogenous oscillations. This system permits both up- and down-regulation of brain oscillations at the target stimulation frequency, 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 39 participants during the retention intervals of a modified Sternberg paradigm. Compared to in-phase alpha-tACS, anti-phase alpha-tACS decreased both WM performance and alpha activity. Moreover, the in-phase tACS-induced changes in WM performance were positively correlated with alpha oscillatory activity. These findings strongly support a causal link between alpha oscillations and WM retention, and illustrate the broad application prospects of phase-locking tACS.

Video game proficiency predicted by EEG oscillatory indexes of visual working memory

“…In a study done by Riddle et al, 26 authors found parietal alpha had a causal role for information suppression in WM. In the pre-print version, Chen et al, 27 indicate a causal link between alpha power and retention in WM. In the mentioned study, researchers apply transcranial alternating current stimulation (tACS) in both in-phase and anti-phase stages to link these interventions with EEG data but also with behavioral outputs.…”

“…In the mentioned study, researchers apply transcranial alternating current stimulation (tACS) in both in-phase and anti-phase stages to link these interventions with EEG data but also with behavioral outputs. 27 Inhibition of unrelated information suppression is a crucial aspect of not only WM but also video game pro ciency, an experience that highly relies on VWM function. Inhibition of non-task-related stimulus processing may be necessary to perform a visual scanning task with high e ciency.…”