Mäki-Marttunen Verónica, Velinov Alexandra, Nieuwenhuis Sander
Cognitive Psychology Unit, Faculty of Social Sciences, Leiden University, Leiden, Alaska 2333, The Netherlands
Cognitive Psychology Unit, Faculty of Social Sciences, Leiden University, Leiden, Alaska 2333, The Netherlands.
eNeuro. 2025 Jan 27;12(1). doi: 10.1523/ENEURO.0064-24.2024. Print 2025 Jan.
The brain attends to environmental rhythms by aligning the phase of internal oscillations. However, the factors underlying fluctuations in the strength of this phase entrainment remain largely unknown. In the present study, we examined whether the strength of low-frequency electroencephalography (EEG) phase entrainment to rhythmic stimulus sequences varied with the pupil size and posterior alpha-band power, thought to reflect the arousal level and excitability of posterior cortical brain areas, respectively. We recorded the pupil size and scalp EEG while participants carried out an intermodal selective attention task, in which they were instructed to attend to a rhythmic sequence of visual or auditory stimuli and ignore the other perceptual modality. As expected, intertrial phase coherence (ITC), a measure of entrainment strength, was larger for the task-relevant than for the task-irrelevant modality. Across the experiment, the pupil size and posterior alpha power were strongly linked with each other. Interestingly, ITC tracked both variables: larger pupil size was associated with a selective increase in entrainment to the task-relevant stimulus sequence, whereas larger posterior alpha power was associated with a decrease in phase entrainment to both the task-relevant and task-irrelevant stimulus sequences. Exploratory analyses showed that a temporal relation between ITC and posterior alpha power emerged in the time periods around pupil maxima and pupil minima. These results indicate that endogenous sources contribute distinctly to the fluctuations of EEG phase entrainment.
大脑通过使内部振荡的相位同步来适应环境节律。然而，这种相位同步强度波动背后的因素在很大程度上仍然未知。在本研究中，我们检验了低频脑电图（EEG）对节律性刺激序列的相位同步强度是否随瞳孔大小和后阿尔法波段功率而变化，这两个因素分别被认为反映了后皮质脑区的唤醒水平和兴奋性。我们记录了参与者在进行跨模态选择性注意任务时的瞳孔大小和头皮脑电图，在该任务中，他们被指示关注视觉或听觉刺激的节律序列，并忽略另一种感知模态。正如预期的那样，作为同步强度度量的试间相位相干性（ITC），与任务相关模态相比，任务无关模态的ITC更大。在整个实验过程中，瞳孔大小和后阿尔法功率彼此密切相关。有趣的是，ITC跟踪了这两个变量：较大的瞳孔大小与对任务相关刺激序列的同步选择性增加有关，而较大的后阿尔法功率与对任务相关和任务无关刺激序列的相位同步减少有关。探索性分析表明，在瞳孔最大值和瞳孔最小值附近的时间段内，ITC和后阿尔法功率之间出现了时间关系。这些结果表明，内源性因素对脑电图相位同步的波动有明显贡献。
