Department of Experimental Psychology, Ghent University, Ghent, B-9000, Belgium.
Neuroscience Institute, New York University Langone Medical Center, New York, New York 10016
J Neurosci. 2021 Jan 6;41(1):167-178. doi: 10.1523/JNEUROSCI.2023-20.2020. Epub 2020 Nov 18.
Prior knowledge profoundly influences perceptual processing. Previous studies have revealed consistent suppression of predicted stimulus information in sensory areas, but how prior knowledge modulates processing higher up in the cortical hierarchy remains poorly understood. In addition, the mechanism leading to suppression of predicted sensory information remains unclear, and studies thus far have revealed a mixed pattern of results in support of either the "sharpening" or "dampening" model. Here, using 7T fMRI in humans (both sexes), we observed that prior knowledge acquired from fast, one-shot perceptual learning sharpens neural representation throughout the ventral visual stream, generating suppressed sensory responses. In contrast, the frontoparietal and default mode networks exhibit similar sharpening of content-specific neural representation, but in the context of unchanged and enhanced activity magnitudes, respectively: a pattern we refer to as "selective enhancement." Together, these results reveal a heretofore unknown macroscopic gradient of prior knowledge's sharpening effect on neural representations across the cortical hierarchy. A fundamental question in neuroscience is how prior knowledge shapes perceptual processing. Perception is constantly informed by internal priors in the brain acquired from past experiences, but the neural mechanisms underlying this process are poorly understood. To date, research on this question has focused on early visual regions, reporting a consistent downregulation when predicted stimuli are encountered. Here, using a dramatic one-shot perceptual learning paradigm, we observed that prior knowledge results in sharper neural representations across the cortical hierarchy of the human brain through a gradient of mechanisms. In visual regions, neural responses tuned away from internal predictions are suppressed. In frontoparietal regions, neural activity consistent with priors is selectively enhanced. These results deepen our understanding of how prior knowledge informs perception.
先前的知识深刻地影响着感知处理。先前的研究揭示了在感觉区域中一致的对预测刺激信息的抑制，但先前的知识如何调节皮质层次结构中更高层次的处理仍然知之甚少。此外，导致预测感觉信息抑制的机制尚不清楚，迄今为止的研究揭示了支持“锐化”或“抑制”模型的混合结果模式。在这里，我们使用人类的 7T fMRI（无论性别），观察到从快速、单次的感知学习中获得的先前知识锐化了腹侧视觉流中的神经表示，从而产生了被抑制的感觉反应。相比之下，额顶叶和默认模式网络表现出类似的内容特异性神经表示的锐化，但分别表现为不变和增强的活动幅度：我们称之为“选择性增强”的模式。总的来说，这些结果揭示了先前知识在皮质层次结构中对神经表示的锐化效应的未知宏观梯度。神经科学中的一个基本问题是先前知识如何塑造感知处理。感知不断受到大脑中从过去经验中获得的内部先验的影响，但这一过程的神经机制仍不清楚。迄今为止，对这个问题的研究主要集中在早期视觉区域，报告了当遇到预测刺激时一致的下调。在这里，我们使用一个戏剧性的单次感知学习范式，观察到先前的知识通过一系列机制导致大脑皮质层次结构中更清晰的神经表示。在视觉区域中，与内部预测不符的神经反应受到抑制。在前顶叶区域，与先验一致的神经活动被选择性地增强。这些结果加深了我们对先前知识如何告知感知的理解。
