Tusa R J, Palmer L A
J Comp Neurol. 1980 Sep 1;193(1):147-64. doi: 10.1002/cne.901930110.
The retinotopic organization of cat cortex, in the vicinity of areas 20 and 21 as defined by Heath and Jones ('71), was determined using electrophysiological mapping techniques. Although the topography of the visual field representations in this region of cortex is more complex than that found in areas 17, 18, and 19, this region appears to contain four representations of the visual hemifield. The four cortical areas these visual field representations occupy have been labeled 20a, 20b, 21a, 21b. These representations are not as precise as those found in areas 17, 18, and 19; the receptive fields in areas 20a, 20b, 21a, and 21b are larger and there is more scatter in receptive field location among adjacent cells. The upper visual hemifield is emphasized in all four of these areas, but the extent of the representation ranges from just the central 20 degrees found in area 21a to nearly the entire upper visual quadrant found in area 20b. The peak areal magnification factors found in these areas are all at least one order of magnitude less than those found in area 17. The visual field transformations from retina onto cortex in areas 20a, 20b, 21a, and 21b are similar to the types we found in other cortical visual areas, and the significance of these transformations for visual processing is discussed.
利用电生理图谱技术，确定了猫皮层在希思和琼斯（1971年）所定义的20区和21区附近的视网膜拓扑组织。尽管该皮层区域中视野表征的拓扑结构比在17区、18区和19区中发现的更为复杂，但该区域似乎包含四个视觉半视野的表征。这些视野表征所占据的四个皮层区域已被标记为20a、20b、21a、21b。这些表征不如在17区、18区和19区中发现的那样精确；20a区、20b区、21a区和21b区中的感受野更大，相邻细胞间感受野位置的分散性也更大。所有这四个区域都着重表征上半视野，但表征范围从21a区中仅中央20度到20b区中几乎整个上半视觉象限不等。在这些区域中发现的峰值面积放大因子都比在17区中发现的至少小一个数量级。20a区、20b区、21a区和21b区中从视网膜到皮层的视野转换与我们在其他皮层视觉区域中发现的类型相似，并且讨论了这些转换对视觉处理的意义。
