University of Ottawa Institute of Mental Health Research, Ottawa, ON K1Z 7K4, Canada.
Biomedical Engineering Group, Higher Technical School of Telecommunications Engineering, University of Valladolid, Valladolid 47011, Spain.
Cereb Cortex. 2022 Aug 3;32(16):3441-3456. doi: 10.1093/cercor/bhab425.
Studies of perception and cognition in schizophrenia (SCZ) show neuronal background noise (ongoing activity) to intermittently overwhelm the processing of external stimuli. This increased noise, relative to the activity evoked by the stimulus, results in temporal imprecision and higher variability of behavioral responses. What, however, are the neural correlates of temporal imprecision in SCZ behavior? We first report a decrease in electroencephalography signal-to-noise ratio (SNR) in two SCZ datasets and tasks in the broadband (1-80 Hz), theta (4-8 Hz), and alpha (8-13 Hz) bands. SCZ participants also show lower inter-trial phase coherence (ITPC)-consistency over trials in the phase of the signal-in theta. From these ITPC results, we varied phase offsets in a computational simulation, which illustrated phase-based temporal desynchronization. This modeling also provided a necessary link to our results and showed decreased neural synchrony in SCZ in both datasets and tasks when compared with healthy controls. Finally, we showed that reduced SNR and ITPC are related and showed a relationship to temporal precision on the behavioral level, namely reaction times. In conclusion, we demonstrate how temporal imprecision in SCZ neural activity-reduced relative signal strength and phase coherence-mediates temporal imprecision on the behavioral level.
精神分裂症（SCZ）的感知和认知研究表明，神经元背景噪声（持续活动）会间歇性地压倒外部刺激的处理。与刺激引起的活动相比，这种增加的噪声导致时间不精确和行为反应的可变性更高。然而，SCZ 行为中时间不精确的神经相关性是什么？我们首先报告了在两个 SCZ 数据集和任务中，脑电图信号噪声比（SNR）在宽带（1-80 Hz）、theta（4-8 Hz）和 alpha（8-13 Hz）频段的降低。SCZ 参与者在 theta 频段的信号相位中也表现出较低的试验间相位相干性（ITPC）-试验一致性。从这些 ITPC 结果中，我们在计算模拟中改变了相位偏移，该模拟说明了基于相位的时间去同步化。这种建模还为我们的结果提供了必要的联系，并表明与健康对照组相比，在两个数据集和任务中，SCZ 的神经同步性降低。最后，我们表明，降低的 SNR 和 ITPC 是相关的，并显示了与行为水平上的时间精度的关系，即反应时间。总之，我们证明了 SCZ 神经活动中的时间不精确性——降低的相对信号强度和相位相干性——如何在行为水平上介导时间不精确性。
