Wynn Syanah C, Marshall Tom R, Nyhus Erika
Neuroimaging Center, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany.
Department of Psychology and Program in Neuroscience, Bowdoin College, Brunswick, ME, United States.
bioRxiv. 2024 Jun 1:2024.05.27.596015. doi: 10.1101/2024.05.27.596015.
The information transfer necessary for successful memory retrieval is believed to be mediated by theta and gamma oscillations. These oscillations have been linked to memory processes in electrophysiological studies, which were correlational in nature. In the current study, we used transcranial alternating current stimulation (tACS) to externally modulate brain oscillations to examine its direct effects on memory performance. Participants received sham, theta (4 Hz), and gamma (50 Hz) tACS over frontoparietal regions while retrieving information in a source memory paradigm. Linear regression models were used to investigate the direct effects of oscillatory non-invasive brain stimulation (NIBS) on memory accuracy and confidence. Our results indicate that both theta and gamma tACS altered memory confidence. Specifically, theta tACS seemed to lower the threshold for confidence in retrieved information, while gamma tACS appeared to alter the memory confidence bias. Furthermore, the individual differences in tACS effects could be predicted from electroencephalogram (EEG) measures recorded prior to stimulation, suggesting that EEG could be a useful tool for predicting individual variability in the efficacy of NIBS.
成功的记忆检索所必需的信息传递被认为是由θ波和γ波振荡介导的。在电生理研究中，这些振荡与记忆过程相关联，而这些研究本质上是相关性的。在当前的研究中，我们使用经颅交流电刺激（tACS）从外部调节脑振荡，以检验其对记忆表现的直接影响。在一个源记忆范式中检索信息时，参与者在前额叶顶叶区域接受了伪刺激、θ波（4赫兹）和γ波（50赫兹）的tACS。线性回归模型被用于研究振荡性非侵入性脑刺激（NIBS）对记忆准确性和信心的直接影响。我们的结果表明，θ波和γ波的tACS都改变了记忆信心。具体而言，θ波tACS似乎降低了对检索到的信息的信心阈值，而γ波tACS似乎改变了记忆信心偏差。此外，tACS效应的个体差异可以从刺激前记录的脑电图（EEG）测量中预测出来，这表明EEG可能是预测NIBS疗效个体差异的有用工具。
