Alpha rhythms (∼10Hz) in the human brain are classically associated with idling activities, being predominantly observed during quiet restfulness with closed eyes. However, recent studies demonstrated that alpha (∼10Hz) rhythms can directly relate to visual stimulation, resulting in oscillations, which can last for as long as one second. This alpha reverberation, dubbed perceptual echoes (PE), suggests that the visual system actively samples and processes visual information within the alpha-band frequency. Although PE have been linked to various visual functions, their underlying mechanisms and functional role are not completely understood. In this study, we investigated the relationship between conscious perception and the generation and the amplitude of PE. Specifically, we displayed two coloured Gabor patches with different orientations on opposite sides of the screen, and using a set of dichoptic mirrors, we induced a binocular rivalry between the two stimuli. We asked participants to continuously report which one of two Gabor patches they consciously perceived, while recording their EEG signals. Importantly, the luminance of each patch fluctuated randomly over time, generating random sequences from which we estimated two impulse-response functions (IRFs) reflecting the PE generated by the perceived (dominant) and non-perceived (suppressed) stimulus, respectively. We found that the alpha power of the PE generated by the consciously perceived stimulus was comparable with that of the PE generated during monocular vision (control condition) and higher than the PE induced by the suppressed stimulus. Moreover, confirming previous findings, we found that all PEs propagated as a travelling wave from posterior to frontal brain regions, irrespective of conscious perception. All in all our results demonstrate a correlation between conscious perception and PE, suggesting that the synchronization of neural activity plays an important role in visual sampling and conscious perception.

中文翻译：

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意识知觉和知觉回声：双眼竞争研究


人脑中的阿尔法节律（~10Hz）通常与闲置活动相关，主要在闭眼安静休息时观察到。然而，最近的研究表明，α（∼10Hz）节律可以与视觉刺激直接相关，从而导致振荡，这种振荡可以持续长达一秒。这种阿尔法混响被称为感知回声（PE），表明视觉系统主动采样和处理阿尔法波段频率内的视觉信息。尽管 PE 与各种视觉功能有关，但其潜在机制和功能作用尚不完全清楚。在这项研究中，我们研究了意识知觉与PE的产生和幅度之间的关系。具体来说，我们在屏幕的两侧显示了两个不同方向的彩色伽博斑块，并使用一组分光镜，我们诱导了两种刺激之间的双眼竞争。我们要求参与者在记录脑电图信号的同时，不断报告他们有意识地感知到的两个 Gabor 斑块中的哪一个。重要的是，每个斑块的亮度随时间随机波动，生成随机序列，从中我们估计两个脉冲响应函数（IRF），分别反映由感知（主导）和非感知（抑制）刺激生成的 PE。我们发现，由有意识感知的刺激产生的 PE 的 α 功率与单眼视觉（控制条件）期间产生的 PE 的 α 功率相当，并且高于由抑制刺激引起的 PE。此外，为了证实之前的发现，我们发现所有 PE 都以行波形式从后脑区域传播到额叶区域，而与意识感知无关。 总而言之，我们的结果证明了意识知觉和 PE 之间的相关性，表明神经活动的同步在视觉采样和意识知觉中发挥着重要作用。