Hall Michelle G, Mattingley Jason B, Dux Paul E
School of Psychology, The University of Queensland , St Lucia, Queensland , Australia.
Queensland Brain Institute, The University of Queensland , St Lucia, Queensland , Australia.
J Neurophysiol. 2018 Apr 1;119(4):1461-1470. doi: 10.1152/jn.00733.2017. Epub 2018 Jan 10.
The human visual system is remarkably sensitive to environmental regularities, which can facilitate behavioral performance when sensory events conform to past experience. The point at which prior knowledge is integrated during visual perception is unclear, particularly for incidentally learned associations. One possibility is that expectation shapes neural activity prospectively, in an anticipatory fashion, allowing prior knowledge to affect the earliest stages of sensory processing. Alternatively, cognitive processes underlying object recognition and conflict detection may be necessary precursors, constraining effects to later stages of processing. Here we used electroencephalography (EEG) to uncover neural activity that distinguishes between visual stimuli that match prior exposure and those that deviate from it. Participants identified visual targets that were associated with possible target locations; each location was associated with a high-probability target and a low-probability target. Alongside a behavioral cost for stimuli that had occurred infrequently at a cued location compared with those that had occurred frequently, we observed a focal modulation of the evoked EEG response at 250 ms after target onset. Relative to likely targets, unlikely targets evoked an enhanced negativity at midline frontal electrodes, and individual differences in the magnitude of this effect were correlated with the response time difference between likely and unlikely targets. In contrast, the evoked response at the latency of the P1, a correlate of early sensory processing, was indistinguishable for likely and unlikely targets. Together, these results point to postperceptual processes as a key stage at which experience modulates visual processing. NEW & NOTEWORTHY We combined electroencephalography with an incidental learning paradigm to investigate whether prior knowledge of environmental regularities modulates visual processing at early or late stages of sensory analysis. Our results reveal that modulations of neural activity arising at midlevel processing stages predict behavioral costs for unexpected stimuli rather than effects at early stages of sensory encoding.
人类视觉系统对环境规律非常敏感，当感官事件符合过去的经验时，这有助于行为表现。在视觉感知过程中，先验知识整合的时间点尚不清楚，尤其是对于偶然学到的关联。一种可能性是，期望以前瞻性的方式塑造神经活动，使先验知识能够影响感觉处理的最早阶段。另一种可能性是，物体识别和冲突检测背后的认知过程可能是必要的前提条件，将影响限制在处理的后期阶段。在这里，我们使用脑电图（EEG）来揭示区分与先前暴露匹配的视觉刺激和与之偏离的视觉刺激的神经活动。参与者识别与可能的目标位置相关联的视觉目标；每个位置都与一个高概率目标和一个低概率目标相关联。与频繁出现在提示位置的刺激相比，偶尔出现在提示位置的刺激存在行为代价，同时，我们观察到目标出现后250毫秒时诱发的EEG反应有局部调制。相对于可能的目标，不太可能的目标在中线额电极处诱发增强的负电位，并且这种效应的大小的个体差异与可能和不太可能的目标之间的反应时间差异相关。相比之下，P1潜伏期的诱发反应（早期感觉处理的一个指标）在可能和不太可能的目标之间没有区别。总之，这些结果表明，感知后过程是经验调节视觉处理的关键阶段。新内容与值得注意之处我们将脑电图与偶然学习范式相结合，以研究环境规律的先验知识是否在感觉分析的早期或晚期阶段调节视觉处理。我们的结果表明，在中级处理阶段出现的神经活动调制预测了意外刺激的行为代价，而不是感觉编码早期阶段的效应。
