Department of Experimental Psychology, Ghent University, Ghent, Belgium.
Division of Psychology, School of Social Sciences, University of Dundee, Dundee, UK.
Eur J Neurosci. 2022 Jun;55(11-12):3241-3255. doi: 10.1111/ejn.15719. Epub 2022 Jun 1.
Pre-stimulus electroencephalogram (EEG) oscillations, especially in the alpha range (8-13 Hz), can affect the sensitivity to temporal lags between modalities in multisensory perception. The effects of alpha power are often explained in terms of alpha's inhibitory functions, whereas effects of alpha frequency have bolstered theories of discrete perceptual cycles, where the length of a cycle, or window of integration, is determined by alpha frequency. Such studies typically employ visual detection paradigms with near-threshold or even illusory stimuli. It is unclear whether such results generalize to above-threshold stimuli. Here, we recorded EEG, while measuring temporal discrimination sensitivity in a temporal-order judgement task using above-threshold auditory and visual stimuli. We tested whether the power and instantaneous frequency of pre-stimulus oscillations predict audiovisual temporal discrimination sensitivity on a trial-by-trial basis. By applying a jackknife procedure to link single-trial pre-stimulus oscillatory power and instantaneous frequency to psychometric measures, we identified a posterior cluster where lower alpha power was associated with higher temporal sensitivity of audiovisual discrimination. No statistically significant relationship between instantaneous alpha frequency and temporal sensitivity was found. These results suggest that temporal sensitivity for above-threshold multisensory stimuli fluctuates from moment to moment and is indexed by modulations in alpha power.
刺激前脑电图 (EEG) 振荡，尤其是在 alpha 频段（8-13Hz），可以影响多感觉感知中模式之间时间滞后的敏感性。alpha 功率的影响通常用 alpha 的抑制功能来解释，而 alpha 频率的影响则支持了离散感知周期的理论，其中一个周期的长度或整合窗口由 alpha 频率决定。此类研究通常采用具有接近阈或甚至幻觉刺激的视觉检测范式。目前尚不清楚这些结果是否适用于阈上刺激。在这里，我们记录了脑电图，同时使用阈上听觉和视觉刺激在时间顺序判断任务中测量时间辨别敏感性。我们测试了刺激前振荡的功率和瞬时频率是否可以逐次预测视听时间辨别敏感性。通过应用刀切程序将单次试验刺激前振荡功率和瞬时频率与心理物理测量联系起来，我们确定了一个后集群，其中较低的 alpha 功率与视听辨别较高的时间敏感性相关。没有发现瞬时 alpha 频率与时间敏感性之间存在统计学上显著的关系。这些结果表明，阈上多感觉刺激的时间敏感性在瞬间波动，并且由 alpha 功率的调制来指示。
