Transcranial alternating current Stimulation (tACS) induced aftereffects in the individual Alpha frequency band: an EEG/fNIRS study

经颅交流电刺激 (tACS) 在个体 α 频段引起的后遗症：一项 EEG/fNIRS 研究

• 批准号: 398325528
• 负责人: Professor Dr. Michael Doppelmayr
• 金额: --
• 依托单位: Abteilung Sportpsychologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/398325528?language=en
• 关键词: Transcranial; alternating; current; Stimulation; tACS

Transcranial alternating current stimulation (tACS) is a highly interesting, new method to modulate brain rhythms. Electrodes are placed on the head and a minimal alternating current (1mA) within a selected frequency is sent through the brain. As far as reported this method can be used in humans without any risk. However, it may alter or modulate brain rhythms and concurrent the discharge pattern of the neurons in the targeted area. The most important brain oszillation in humans is the alpha rhythm with a frequency of about 10 Hz. Because alpha frequency can vary between subjects, for stimulation and analysis the individually adjusted alpha frequency (IAF) is used.Recent studies indicated that a) IAF adjusted tACS can enhance the amplitudes of the electroencephalogram (EEG) in this frequency for up to 90 minutes (Kasten et al.2016) b) if an implicit motor learning paradigm as a “serial reaction time task” (SRTT) is executed during tACS, this can increase learning performance (Pollok et al. 2015).Based on these findings we will perform a study including a 20 minute tACS adjusted to the IAF. We will also include a SRTT and we will analyze the effects for six hours after the stimulation. Forty male participants, double-blind divided in a stimulation (Stim) and a sham stimulation (Sham) group, will voluntarily take part in the experiment. We will focus on the effects of IAF-tACS on the EEG amplitudes, on learning performance and on the blood oxygenation in the brain, as assessed by functional near infrared spectroscopy (fNIRS). Three main questions will be answered:i) It has been reported that IAF-tACS can enhance the EEG amplitudes in this frequency range for up to 90 minutes. In a pilot study we have observed increased amplitudes for more than three hours after the stimulation. Thus, we will analyze the duration of this after effect for up to six hours after the tACS.ii) implicit motor learning paradigms as the SRTT yield better results if trained with accompanying tACS. If this positive effect is due to the tACS induced enhanced amplitudes, learning effectivity should be increased too, as long as the amplitudes are enhanced. Thus, the participants will perform the SRTT repeatedly after the tACS (assuming there are enlevated amplitudes) and we will analyze the learning efficiency.iii) Up to now there is no single report about whether the increase of the EEG amplitudes during tACS is correlated to an accompanying increased or decreased brain activity. Thus, we will record brain blood oxygenation by the means of fNIRS, as a measure of brain activity. fNIRS will be recorded before, during and after tACS.Taken together these are three highly relevant topics that will be answered with this study. The results are of high importance both, for the understanding of the basic mechanisms of tACS as well as for potential therapeutic applications.

经颅交流电刺激（tACS）是一种非常有趣的调节脑节律的新方法。电极被放置在头部，一个最小的交流电（1mA）在一个选定的频率内通过大脑。据报道，这种方法可以用于人类没有任何风险。然而，它可能改变或调节脑节律，并发目标区域神经元的放电模式。人类大脑中最重要的振荡是频率约为10赫兹的α节律。由于α频率在受试者之间可能不同，因此在刺激和分析中使用单独调整的α频率（IAF）。最近的研究表明，a) IAF调整后的tACS可以在长达90分钟的时间内增强该频率的脑电图（EEG）振幅（Kasten et al.2016） b)如果在tACS期间执行内隐运动学习范式作为“系列反应时间任务”（SRTT），这可以提高学习表现（Pollok et al. 2015）。基于这些发现，我们将进行一项研究，其中包括调整到IAF的20分钟tACS。我们还会进行SRTT我们会分析刺激后6小时的效果。40名男性参与者，双盲分为刺激组（Stim）和假刺激组（sham），自愿参加实验。我们将重点关注IAF-tACS对脑电图振幅、学习表现和大脑血氧的影响，这些影响是通过功能近红外光谱（fNIRS）来评估的。将回答三个主要问题：i)据报道，IAF-tACS可以增强该频率范围内的脑电图幅度长达90分钟。在一项初步研究中，我们观察到刺激后三个多小时的振幅增加。因此，我们将在tACS结束后的6个小时内分析这种后效的持续时间。ii)内隐动作学习范式作为SRTT，如果辅以tACS训练，效果会更好。如果这种积极效果是由于tACS诱导的振幅增强，那么只要振幅增强，学习效率也应该提高。因此，参与者将在tACS之后重复执行SRTT（假设有振幅升高），我们将分析学习效率。iii)到目前为止，关于tACS期间脑电图振幅的增加是否与脑活动的增加或减少相关，尚无单一的报道。因此，我们将通过近红外光谱（fNIRS）来记录脑血氧合，作为衡量大脑活动的一种手段。在tac之前、期间和之后记录fNIRS。综上所述，这三个高度相关的主题将在本研究中得到解答。这些结果对于了解tACS的基本机制以及潜在的治疗应用都具有重要意义。