Department of Clinical Neurophysiology, University Medical Center Göttingen, Göttingen 37073, Germany
Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany.
eNeuro. 2020 Sep 8;7(5). doi: 10.1523/ENEURO.0126-20.2020. Print 2020 Sep/Oct.
Cognitive control is a mental process, which underlies adaptive goal-directed decisions. Previous studies have linked cognitive control to electrophysiological fluctuations in the θ band and θ-γ cross-frequency coupling (CFC) arising from the cingulate and frontal cortices. However, to date, the behavioral consequences of different forms of θ-γ CFC remain elusive. Here, we studied the behavioral effects of the θ-γ CFC via transcranial alternating current stimulation (tACS) designed to stimulate the frontal and cingulate cortices in humans. Using a double-blind, randomized, repeated measures study design, 24 healthy participants were subjected to three active and one control CFC-tACS conditions. In the active conditions, 80-Hz γ tACS was coupled to 4-Hz θ tACS. Specifically, in two of the active conditions, short γ bursts were coupled to the delivered θ cycle to coincide with either its peaks or troughs. In the third active condition, the phase of a θ cycle modulated the amplitude of the γ oscillation. In the fourth, control protocol, 80-Hz tACS was continuously superimposed over the 4-Hz tACS, therefore lacking any phase specificity in the CFC. During the 20 min of stimulation, the participants performed a Go/NoGo monetary reward-based and punishment-based instrumental learning task. A Bayesian hierarchical logistic regression analysis revealed that relative to the control, the peak-coupled tACS had no effects on the behavioral performance, whereas the trough-coupled tACS and, to a lesser extent, amplitude-modulated tACS reduced performance in conflicting trials. Our results suggest that cognitive control depends on the phase specificity of the θ-γ CFC.
认知控制是一种心理过程，它是适应性目标导向决策的基础。先前的研究将认知控制与θ 频段的电生理波动以及来自扣带回和额皮质的θ-γ 交叉频域耦合（CFC）联系起来。然而，迄今为止，不同形式的θ-γ CFC 的行为后果仍然难以捉摸。在这里，我们通过经颅交流电刺激（tACS）研究了θ-γ CFC 的行为效应，该刺激旨在刺激人类的额皮质和扣带回皮质。使用双盲、随机、重复测量研究设计，24 名健康参与者接受了三种主动和一种对照 CFC-tACS 条件的测试。在主动条件下，80HzγtACS 与 4HzθtACS 耦合。具体来说，在两种主动条件下，短γ 爆发与传递的θ 周期耦合，以与它们的峰值或波谷重合。在第三种主动条件下，θ 周期的相位调制γ 振荡的幅度。在第四种对照方案中，80Hz tACS 连续叠加在 4Hz tACS 上，因此在 CFC 中缺乏任何相位特异性。在 20 分钟的刺激过程中，参与者执行了一个基于 Go/NoGo 货币奖励和惩罚的工具学习任务。贝叶斯层次逻辑回归分析表明，与对照相比，峰值耦合 tACS 对行为表现没有影响，而谷值耦合 tACS 以及在较小程度上，幅度调制 tACS 降低了冲突试验中的表现。我们的结果表明，认知控制取决于θ-γ CFC 的相位特异性。
