从背景中检测和分割有意义的人物是视觉的主要功能之一。虽然在非人类灵长类动物中的工作涉及这种图形-地面调制中的早期视觉机制,人类的神经成像在很大程度上将数字和物体的处理归因于视觉层次结构的更高阶段。这里,我们使用7特斯拉的高场功能磁共振成像来测量人类早期视觉皮层(N=6,4名女性)对任务无关方向定义图形的BOLD反应。我们使用了一种新颖的基于种群感受场映射的方法来解决图形-地面调制的两种组成机制的空间分布:局部边界响应,以及由特征的全局差异驱动的跨越图形区域的全部范围的进一步增强。重建这些效应的独特空间轮廓表明,图形增强以与自动,来自更高视觉区域的上下文驱动反馈。重要声明视觉系统的核心功能是将复杂的2D输入解析为有意义的图形。我们不断地无缝地这样做,通过处理有关可见边缘的信息以及分析图形和背景之间的大规模差异。虽然有影响力的神经生理学工作具有一种有趣的机制,可以增强V1对感知数字的反应,我们对早期视觉系统如何有助于人类的图形-地面处理知之甚少。这里,我们使用先进的计算分析方法和高场人体fMRI数据来解析早期视觉系统(V1和LGN)中局部边缘和全局图形增强的不同空间轮廓;后者是独特的,并且与自动,来自更高层次视觉区域的刺激驱动反馈。
The detection and segmentation of meaningful figures from their background is one of the primary functions of vision. While work in nonhuman primates has implicated early visual mechanisms in this figure-ground modulation, neuroimaging in humans has instead largely ascribed the processing of figures and objects to higher stages of the visual hierarchy. Here, we used high-field fMRI at 7 Tesla to measure BOLD responses to task-irrelevant orientation-defined figures in human early visual cortex (N = 6, four females). We used a novel population receptive field mapping-based approach to resolve the spatial profiles of two constituent mechanisms of figure-ground modulation: a local boundary response, and a further enhancement spanning the full extent of the figure region that is driven by global differences in features. Reconstructing the distinct spatial profiles of these effects reveals that figure enhancement modulates responses in human early visual cortex in a manner consistent with a mechanism of automatic, contextually driven feedback from higher visual areas.SIGNIFICANCE STATEMENT A core function of the visual system is to parse complex 2D input into meaningful figures. We do so constantly and seamlessly, both by processing information about visible edges and by analyzing large-scale differences between figure and background. While influential neurophysiology work has characterized an intriguing mechanism that enhances V1 responses to perceptual figures, we have a poor understanding of how the early visual system contributes to figure-ground processing in humans. Here, we use advanced computational analysis methods and high-field human fMRI data to resolve the distinct spatial profiles of local edge and global figure enhancement in the early visual system (V1 and LGN); the latter is distinct and consistent with a mechanism of automatic, stimulus-driven feedback from higher-level visual areas.