Abstract

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.

中文翻译：

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压力和经颅直流电刺激（tDCS）对工作记忆的影响：一项随机对照试验。

摘要

经颅直流电刺激（tDCS）的最新评论显示，对其最初引用的对工作记忆（WM）的增强作用的支持有限。他们强调需要进行其他研究，评估可优化刺激结果的具体情况。在这方面，社会压力是一个有吸引力的候选者，因为它会影响WM，并由前额叶皮层活动介导。因此，针对这些神经网络的tDCS可能会与社会压力相互作用，从而影响WM。我们的目标是探讨健康人群中社会压力和tDCS对WM表现的相互作用，将69名女性参与者随机分配到四个实验条件（即2×2设计）：刺激（dlPFC tDCS与假刺激）和压力操纵（特里尔社会压力测试[TSST]程序与友好对照的TSST）。Ñ -back任务），以及应力的主观/客观指标进行了评估。发现显着的刺激×压力操纵相互作用，F（1，65）= 6.208，p = .015，表明活动的tDCS可以在无压力条件下提高WM性能，而在压力下降低WM性能。然而，方差的后续分析并不显着（即，ps = .083 / .093），贝叶斯分析尚无定论。总之，压力似乎是决定tDCS效果的关键因素，tDCS可能在较低压力水平下对WM有增强作用，而在较高压力水平下则有不利影响（即，反转作用方向）。讨论了研究结果的可能的理论基础，同时承认有待进一步研究。