Absence of Alpha-tACS Aftereffects in Darkness Reveals Importance of Taking Derivations of Stimulation Frequency and Individual Alpha Variability Into Account.
Absence of Alpha-tACS Aftereffects in Darkness Reveals Importance of Taking Derivations of Stimulation Frequency and Individual Alpha Variability Into Account.
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DOI：
10.3389/fpsyg.2018.00984
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发表时间：
2018
影响因子：
3.8
通讯作者：
Herrmann CS
中科院分区：
文献类型：
--
作者：
Stecher HI;Herrmann CS
经颅交流电刺激（tACS）已被广泛用作探索脑振荡作用的基本工具。许多研究表明，频率特异性的tACS不仅能够在刺激过程中改变认知过程，而且还能引起脑电图（EEG）上可见的特定生理后遗症。这些后遗症的出现与刺激的必要持续时间之间的关系尚无定论。我们在这项研究中的目标是缩小tac -阻滞的关键长度，通过它可以引起后遗症。我们用α-tACS刺激被试，分别以1分钟、3分钟、5分钟和10分钟为长度，依次递增和递减。在每个脑块之后，我们在一个视觉警戒任务中测量静息脑电图10分钟。与假手术组相比，刺激组在任何刺激阻断后均未发现α-权能的持续增强。这些发现没有提供关于关键刺激持续时间的信息。此外，这与先前的研究结果相冲突，表明在α范围内进行10分钟的tACS后功率增加。基于已知的(1)刺激频率与个体α频率不匹配和(2)基线α-活性异常的混淆，我们进行了额外的探索性分析。ANCOVA的结果表明，这两个因素都解释了方差，但不能确切地解决这两个因素是如何干扰刺激效应的。采用线性混合模型，我们发现α-tACS刺激10 min后，α-tACS刺激的效果显著，刺激频率与个体α频率不匹配的影响显著。讨论了这些发现对未来研究的意义。
Transcranial alternating current stimulation (tACS) has found widespread use as a basic tool in the exploration of the role of brain oscillations. Many studies have shown that frequency-specific tACS is able to not only alter cognitive processes during stimulation, but also cause specific physiological aftereffects visible in the electroencephalogram (EEG). The relationship between the emergence of these aftereffects and the necessary duration of stimulation is inconclusive. Our goal in this study was to narrow down the crucial length of tACS-blocks, by which aftereffects can be elicited. We stimulated participants with α-tACS in four blocks of 1-, 3-, 5-, and 10-min length, once in increasing and once in decreasing order. After each block, we measured the resting EEG for 10 min during a visual vigilance task. We could not find lasting enhancement of α-power following any stimulation block, when comparing the stimulated groups to the sham group. These findings offer no information regarding the crucial stimulation duration. In addition, this conflicts with previous findings, showing a power increase following 10 min of tACS in the alpha range. We performed additional explorative analyses, based on known confounds of (1) mismatches between stimulation frequency and individual alpha frequency and (2) abnormalities in baseline α-activity. The results of an ANCOVA suggested that both factor explain variance, but could not resolve how exactly both factors interfere with the stimulation effect. Employing a linear mixed model, we found a significant effect of stimulation following 10 min of α-tACS in the increasing sequence and a significant effect of the mismatch between stimulated frequency and individual alpha frequency. The implications of these findings for future research are discussed.
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影响因子：
2.7
作者：
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通讯作者：
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影响因子：
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