Department of Psychology, Yangzhou University, Yangzhou, 225000, China; Department of Neuroscience, Karolinska Institutet, Stockholm, 17177, Sweden.
Department of Neuroscience, Karolinska Institutet, Stockholm, 17177, Sweden.
Brain Stimul. 2022 Nov-Dec;15(6):1439-1447. doi: 10.1016/j.brs.2022.10.009. Epub 2022 Oct 31.
Using transcranial alternating current stimulation (tACS) to improve visuospatial working memory (vsWM) has received considerable attention over the past few years. However, fundamental issues remain, such as the optimal frequency, the generality of behavioral effects, and the anatomical specificity of stimulation.
Here we examined the effects of two theory-driven tACS protocols for improving vsWM on behavioral and electroencephalogram (EEG) measures.
Twenty adults each completed 3 HD-tACS conditions (Tuned, Slow, and Sham) on two separate days. The Tuned condition refers to a situation in which the frequency of tACS is tuned to individual theta peak measured during a vsWM task. By contrast, the frequency was fixed to 4 Hz in the Slow condition. A high-definition tACS was deployed to target smaller frontal and parietal regions for increasing their phase-locking values. During each tACS condition, participants performed vsWM, mental rotation (MR), and arithmetic tasks. Resting-state EEG (rs-EEG) was recorded before and after each condition.
Compared with Sham, Tuned but not Slow improved both vsWM and MR but not arithmetics. The rs-EEG recording showed an increased fronto-parietal synchrony for Tuned, and this increase in synchronicity was correlated with the behavioral improvement. A follow-up study showed no behavioral improvement in Tuned with an anti-phase setting.
We provide the first evidence that simulating right fronto-parietal network with the tuned frequency increases the interregional synchronicity and improves performance on two spatial tasks. The results provide insight into the structure of spatial abilities as well as suggestions for stimulating the fronto-parietal network.
在过去几年中，使用经颅交流电刺激（tACS）来改善视空间工作记忆（vsWM）受到了广泛关注。然而，仍存在一些基本问题，例如最佳频率、行为效应的普遍性以及刺激的解剖学特异性。
本研究旨在通过行为和脑电图（EEG）测量来检验两种理论驱动的 tACS 方案对改善 vsWM 的效果。
20 名成年人在两天内分别完成了 3 种 HD-tACS 条件（调谐、慢和假）。调谐条件是指 tACS 的频率与在 vsWM 任务中测量到的个体 theta 峰相匹配的情况。相比之下，慢条件的频率固定为 4 Hz。高清晰度 tACS 用于靶向更小的额顶区域以增加其相位锁定值。在每个 tACS 条件下，参与者执行 vsWM、心理旋转（MR）和算术任务。在每个条件前后记录静息状态 EEG（rs-EEG）。
与假相比，调谐而非慢调改善了 vsWM 和 MR，但不改善算术。rs-EEG 记录显示调谐时额顶同步性增加，这种同步性的增加与行为改善相关。一项后续研究表明，在调谐时采用反相设置没有改善行为。
我们首次提供了证据，表明模拟右额顶网络的调谐频率可以增加区域间的同步性，并改善两项空间任务的表现。研究结果为空间能力的结构提供了新的认识，并为刺激额顶网络提供了建议。
