Prestimulus alpha power but not phase influences visual discrimination of long‐duration visual stimuli
Prestimulus alpha power but not phase influences visual discrimination of long‐duration visual stimuli
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DOI：
10.1111/ejn.15169
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发表时间：
2021-03
影响因子：
3.4
通讯作者：
Georgios Michail;Lino Toran Jenner;J. Keil
中科院分区：
文献类型：
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作者：
Georgios Michail;Lino Toran Jenner;J. Keil
枕部阿尔法频段的振荡与视觉知觉和注意力密切相关。在多项研究中，增加阿尔法功率已被证明可以降低难以检测的视觉刺激的检测率。最近的研究通过改变知觉偏差来解释这一发现。此外，刺激开始前的阿尔法振荡阶段对于视觉刺激的检测似乎是至关重要的。这是因为在每个阿尔法周期的过程中，大脑皮层兴奋性的变化。然而，以前的研究经常使用视觉刺激在知觉阈值上的短呈现时间。在这里，我们使用更长的呈现时间来阐明相同的机制是否适用于呈现长达1500毫秒的显著但具有挑战性的视觉刺激的感知。为此，我们在两种选择的强迫选择任务中向参与者呈现了难以区分但突出的直立或倾斜的高斯栅格，同时记录枕叶脑电活动。以前的报告将阿尔法功率与刺激检测命中率联系起来，我们发现，个体阿尔法频率上的低刺激前功率与较高的感知准确性有关。与最近的发现相反，我们既没有发现阿尔法功率对判据的影响，也没有发现阿尔法阶段对知觉或反应速度的影响。我们认为，更长的呈现时间可能会减弱可能的反应偏差，而更高的兴奋性可能会增强辨别能力，从而导致感知准确性的提高和不受影响的反应标准。
Occipital oscillations in the alpha band are closely related to visual perception and attention. In multiple studies, increased alpha power has been shown to reduce detection rates of hard‐to‐detect visual stimuli. Recent studies explain this finding by a shift in perceptual bias. Moreover, the phase of alpha oscillations prior to stimulus onset appears to be critical for the detection of visual stimuli. This is explained by a shift in cortical excitability over the course of each alpha cycle. However, prior studies often used short presentation times of visual stimuli at the perceptual threshold. Here, we use longer presentation times to elucidate whether the same mechanisms hold for the perception of salient but challenging visual stimuli presented for up to 1,500 ms. To this end, we presented participants with hard to distinguish but salient upright or tilted Gaussian gratings in a two‐alternative forced choice task, while recording occipital electroencephalographic activity. Previous reports link alpha power to stimulus detection hit rates, and we found that low prestimulus power at the individual alpha frequency relates to higher perceptual accuracy. Contrary to recent findings, we neither found an influence of alpha power on criterion, nor an influence of alpha phase on perception or response speed. We argue that longer presentation times might attenuate a possible response bias, and increased excitability might sharpen the discrimination ability, thereby leading to increased perceptual accuracy and unaffected response criterion.