Vision Science Group, Helen Wills Neuroscience Institute and School of Optometry, University of California, Berkeley, CA, USA; Center for Mind and Brain, University of California, Davis, CA, USA.
Eur J Neurosci. 2014 Feb;39(4):593-601. doi: 10.1111/ejn.12418. Epub 2013 Nov 20.
The spatial components of a visual scene are processed neurally in a sequence of coarse features followed by fine features. This coarse-to-fine temporal stream was initially considered to be a cortical function, but has recently been demonstrated in the dorsal lateral geniculate nucleus. The goal of this study was to test the hypothesis that coarse-to-fine processing is present at earlier stages of visual processing in the retinal ganglion cells that supply lateral geniculate nucleus (LGN) neurons. To compare coarse-to-fine processing in the cat's visual system, we measured the visual responses of connected neuronal pairs from the retina and LGN, and separate populations of cells from each region. We found that coarse-to-fine processing was clearly present at the ganglion cell layer of the retina. Interestingly, peak and high-spatial-frequency cutoff responses were higher in the LGN than in the retina, indicating that there was a progressive cascade of coarse-to-fine information from the retina to the LGN to the visual cortex. The analysis of early visual pathway receptive field characteristics showed that the physiological response interplay between the center and surround regions was consistent with coarse-to-fine features and may provide a primary role in the underlying mechanism. Taken together, the results from this study provided a framework for understanding the emergence and refinement of coarse-to-fine processing in the visual system.
视觉场景的空间成分在神经中以粗特征 followed by 细特征的顺序进行处理。这种从粗到细的时间流最初被认为是皮质功能，但最近在背外侧膝状体核中得到了证明。本研究的目的是检验以下假设：在为外侧膝状体核（LGN）神经元提供输入的视网膜神经节细胞中，视觉处理的早期阶段存在从粗到细的处理。为了比较猫的视觉系统中的从粗到细的处理，我们测量了来自视网膜和 LGN 的连接神经元对以及来自每个区域的分离细胞群体的视觉反应。我们发现，在视网膜的神经节细胞层中明显存在从粗到细的处理。有趣的是，在 LGN 中，峰值和高空间频率截止响应高于视网膜，表明从视网膜到 LGN 再到视觉皮层存在信息的逐渐级联从粗到细。对早期视觉通路感受野特征的分析表明，中心和周围区域之间的生理反应相互作用与从粗到细的特征一致，并且可能在潜在机制中发挥主要作用。总之，这项研究的结果为理解视觉系统中从粗到细的处理的出现和细化提供了一个框架。
