Department of Vision and Cognition, Netherlands Institute for Neuroscience (KNAW), Amsterdam 1105 BA, Netherlands.
Momilab Research Unit, Institutions, Markets, Technologies School for Advanced Studies Lucca, Lucca 55100, Italy.
Proc Natl Acad Sci U S A. 2024 Nov 12;121(46):e2221623121. doi: 10.1073/pnas.2221623121. Epub 2024 Nov 4.
The visual system needs to identify perceptually relevant borders to segment complex natural scenes. The primary visual cortex (V1) is thought to extract local borders, and higher visual areas are thought to identify the perceptually relevant borders between objects and the background. To test this conjecture, we used natural images that had been annotated by human observers who marked the perceptually relevant borders. We assessed the effect of perceptual relevance on V1 responses using human neuroimaging, macaque electrophysiology, and computational modeling. We report that perceptually relevant borders elicit stronger responses in the early visual cortex than irrelevant ones, even if simple features, such as contrast and the energy of oriented filters, are matched. Moreover, V1 neurons discriminate perceptually relevant borders surprisingly fast, during the early feedforward-driven activity at a latency of ~50 ms, indicating that they are tuned to the features that characterize them. We also revealed a delayed, contextual effect that enhances the V1 responses that are elicited by perceptually relevant borders at a longer latency. Our results reveal multiple mechanisms that allow V1 neurons to infer the layout of objects in natural images.
视觉系统需要识别出感知相关的边界，以分割复杂的自然场景。人们认为初级视觉皮层（V1）提取局部边界，而更高的视觉区域则识别物体和背景之间的感知相关边界。为了验证这一假设，我们使用了已经被人类观察者标记出感知相关边界的自然图像。我们使用人类神经影像学、猕猴电生理学和计算模型来评估感知相关性对 V1 反应的影响。我们报告说，即使匹配了简单的特征，如对比度和方向滤波器的能量，感知相关的边界也会在早期视觉皮层中引起比不相关的边界更强的反应。此外，V1 神经元可以在大约 50 毫秒的早期前馈驱动活动期间非常快速地区分感知相关的边界，这表明它们对特征有调谐。我们还揭示了一个延迟的上下文效应，它增强了在较长潜伏期由感知相关边界引起的 V1 反应。我们的研究结果揭示了多种机制，使 V1 神经元能够推断自然图像中物体的布局。
