Department of Psychology, Ariel University, Ariel, Israel.
Clinical Research Center for Brain Sciences, Herzog Medical Center, Jerusalem, Israel.
Cogn Affect Behav Neurosci. 2020 Feb;20(1):103-114. doi: 10.3758/s13415-019-00755-7.
Recent reviews of transcranial direct current stimulation (tDCS) show limited support for its initially cited enhancing effects on working memory (WM). They highlight the need for additional research, assessing the specific circumstances that optimize stimulation outcome. Social stress is an attractive candidate in this regard, as it affects WM and is mediated by prefrontal cortex activity; tDCS that targets these neuronal networks may, therefore, interact with social stress to affect WM. Our objective was to explore the interaction between social stress and tDCS on WM performance in a healthy cohort, 69 female participants were randomized to four experimental conditions (i.e., 2 × 2 design): stimulation (dlPFC tDCS vs. sham stimulation) and stress manipulation (Trier Social Stress Test [TSST] procedure vs. a friendly control TSST). Participants' attention, WM (assessed using an n-back task), and subjective/objective indicators of stress were assessed. A significant Stimulation × Stress Manipulation interaction was found, F(1, 65) = 6.208, p = .015, suggesting that active tDCS may increase WM performance in the no-stress conditions, while decreasing it under stress. Follow-up analyses of variance, however, were not significant (i.e., ps=.083 / .093), and Bayesian analyses were inconclusive. In conclusion, stress seems to be a crucial factor in determining the effects of tDCS, and tDCS may have an enhancing effect on WM at lower levels of stress, while being detrimental at higher stress levels (i.e., reversing the direction of effect). Possible theoretical underpinnings of the findings are discussed, while acknowledging the need for further research.
最近对经颅直流电刺激（tDCS）的综述表明，其最初被引用的增强工作记忆（WM）的效果有限。它们强调需要进行额外的研究，评估优化刺激效果的具体情况。社会压力在这方面是一个有吸引力的候选因素，因为它会影响 WM，并且由前额叶皮层活动介导；因此，针对这些神经元网络的 tDCS 可能会与社会压力相互作用，从而影响 WM。我们的目的是在健康队列中探索社会压力和 tDCS 对 WM 表现的相互作用，共有 69 名女性参与者被随机分配到四个实验条件（即 2×2 设计）：刺激（dlPFC tDCS 与假刺激）和应激操纵（特里尔社会应激测试 [TSST] 程序与友好控制 TSST）。评估了参与者的注意力、WM（使用 n-back 任务评估）和压力的主观/客观指标。发现刺激×应激操纵的交互作用显著，F（1,65）=6.208，p=.015，表明在无应激条件下，主动 tDCS 可能会提高 WM 表现，而在应激下则会降低 WM 表现。然而，方差的后续分析并不显著（即，p=.083/.093），贝叶斯分析也没有得出结论。总之，压力似乎是决定 tDCS 效果的关键因素，tDCS 可能在较低的压力水平下对 WM 有增强作用，而在较高的压力水平下则会产生不利影响（即，改变效果的方向）。讨论了这些发现的可能理论基础，同时承认需要进一步的研究。
