Background: Neurofeedback training (NFT) has recently been proposed as a valuable technique for cognitive enhancement and psychiatric amelioration. However, effect of NFT of alpha activity on memory is controversial. The current study analyzed previous works in terms of randomized and blinded analyses, training paradigms, and participant characteristics to validate the efficacy of alpha NFT on memory in a healthy population. Objectives: A systematic meta-analysis of studies with randomized controlled trials was performed to explore the effect of alpha NFT on working memory (WM) and episodic memory (EM) in a healthy population. Methods: We searched PubMed, Embase, and Cochrane Library from January 1, 1999, to November 30, 2019. Previous studies were evaluated with the Cochrane risk of bias (RoB). A meta-analysis calculating absolute weighted standardized mean difference (SMD) using random-effects models was employed. Heterogeneity was estimated using I2 statistics. Funnel plots and Egger's test were performed to evaluate the quality of evidence. Results: Sixteen studies with 217 healthy participants in the control group and 210 participants in the alpha group met the eligibility criteria. Alpha NFT studies with WM measures presented little publication bias (P = 0.116), and 5 of 7 domains in the Cochrane RoB exhibited a low risk of bias. The overall effect size from 14 WM studies was 0.56 (95% CI 0.31–0.81, P < 0.0001; I2 = 28%). Six EM studies exhibited an effect size of 0.77 (95% CI 0.06–1.49, P = 0.03; I2 = 77%). Conclusion: Meta-analysis results suggest that alpha NFT seems to have a positive effect on the WM and EM of healthy participants. Future efforts should focus on the neurophysiological mechanisms of alpha NFT in memory.

中文翻译：

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阿尔法活动对健康参与者记忆的神经反馈：系统回顾和荟萃分析


背景：神经反馈训练（NFT）最近被提出作为认知增强和精神改善的一种有价值的技术。然而，α 活动的 NFT 对记忆的影响存在争议。当前的研究从随机和盲法分析、训练范式和参与者特征方面分析了先前的工作，以验证 alpha NFT 对健康人群记忆的功效。目的：对随机对照试验研究进行系统荟萃分析，以探讨 alpha NFT 对健康人群工作记忆（WM）和情景记忆（EM）的影响。方法：我们检索了 1999 年 1 月 1 日至 2019 年 11 月 30 日期间的 PubMed、Embase 和 Cochrane 图书馆。之前的研究采用 Cochrane 偏倚风险 (RoB) 进行评估。采用使用随机效应模型计算绝对加权标准化平均差（SMD）的荟萃分析。使用 I2 统计数据估计异质性。进行漏斗图和艾格检验来评估证据的质量。结果：包含 217 名健康对照组参与者和 210 名 α 组参与者的 16 项研究符合资格标准。采用 WM 测量的 Alpha NFT 研究几乎没有出现发表偏倚 (P = 0.116)，并且 Cochrane RoB 中 7 个领域中有 5 个显示出较低的偏倚风险。 14 项 WM 研究的总体效应大小为 0.56（95% CI 0.31–0.81，P < 0.0001；I2 = 28%）。六项 EM 研究的效应大小为 0.77（95% CI 0.06–1.49，P = 0.03；I2 = 77%）。结论：荟萃分析结果表明 alpha NFT 似乎对健康参与者的 WM 和 EM 有积极影响。未来的努力应该集中在记忆中α NFT 的神经生理学机制上。