Department of Brain and Cognitive Science, Ben Gurion University of the Negev, Beer-Sheva, Israel.
Department of Psychology, Ben Gurion University of the Negev, Beer-Sheva, Israel.
J Neurophysiol. 2021 Apr 1;125(4):1111-1120. doi: 10.1152/jn.00355.2020. Epub 2021 Feb 3.
Remarkable trial-by-trial variability is apparent in cortical responses to repeating stimulus presentations. This neural variability across trials is relatively high before stimulus presentation and then reduced (i.e., quenched) ∼0.2 s after stimulus presentation. Individual subjects exhibit different magnitudes of variability quenching, and previous work from our lab has revealed that individuals with larger variability quenching exhibit lower (i.e., better) perceptual thresholds in a contrast discrimination task. Here, we examined whether similar findings were also apparent in a motion detection task, which is processed by distinct neural populations in the visual system. We recorded EEG data from 35 adult subjects as they detected the direction of coherent motion in random dot kinematograms. The results demonstrated that individual magnitudes of variability quenching were significantly correlated with coherent motion thresholds, particularly when presenting stimuli with low dot densities, where coherent motion was more difficult to detect. These findings provide consistent support for the hypothesis that larger magnitudes of neural variability quenching are associated with better perceptual abilities in multiple visual domain tasks. The current study demonstrates that better visual perception abilities in a motion discrimination task are associated with larger quenching of neural variability. In line with previous studies and signal detection theory principles, these findings support the hypothesis that cortical sensory neurons increase reproducibility to enhance detection and discrimination of sensory stimuli.
在重复刺激呈现时，皮质反应明显存在显著的逐次变异性。这种跨试验的神经变异性在刺激呈现前相对较高，然后在刺激呈现后约 0.2 秒降低（即被抑制）。个体受试者表现出不同程度的变异性抑制，我们实验室的先前工作表明，变异性抑制较大的个体在对比度辨别任务中表现出较低（即更好）的感知阈值。在这里，我们研究了在运动检测任务中是否也存在类似的发现，运动检测任务由视觉系统中不同的神经群体处理。我们记录了 35 名成年受试者在随机点运动图中检测连贯运动方向时的 EEG 数据。结果表明，个体变异性抑制的幅度与连贯运动阈值显著相关，尤其是在呈现低点数密度的刺激时，因为连贯运动更难检测。这些发现为假设提供了一致的支持，即更大幅度的神经变异性抑制与多种视觉领域任务中的更好感知能力相关。本研究表明，在运动辨别任务中更好的视觉感知能力与更大的神经变异性抑制有关。与先前的研究和信号检测理论原则一致，这些发现支持了这样的假设，即皮质感觉神经元增加可重复性以增强对感觉刺激的检测和辨别。
