Wässle H, Grünert U, Röhrenbeck J, Boycott B B
Max-Planck-Institut für Hirnforschung, Frankfurt, FRG.
Nature. 1989 Oct 19;341(6243):643-6. doi: 10.1038/341643a0.
It has long been contentious whether the large representation of the fovea in the primate visual cortex (V1) indicates a selective magnification of this part of the retina, or whether it merely reflects the density of retinal ganglion cells. The measurement of the retinal ganglion-cell density is complicated by lateral displacements of cells around the fovea and the presence of displaced amacrine cells in the ganglion cell layer. We have now identified displaced amacrine cells by GABA immunohistochemistry and by retrograde degeneration of ganglion cells. By reconstructing the fovea from serial sections, we were able to compare the densities of cones, cone pedicles and ganglion cells; in this way we found that there are more than three ganglion cells per foveal cone. Between the central and the peripheral retina, the ganglion cell density changes by a factor of 1,000-2,000, which is within the range of estimates of the cortical magnification factor. There is therefore no need to postulate a selective magnification of the fovea in the geniculate and/or the visual cortex.
长期以来，灵长类动物视觉皮层（V1）中中央凹的大量表征是表明视网膜这一部分的选择性放大，还是仅仅反映视网膜神经节细胞的密度，一直存在争议。视网膜神经节细胞密度的测量因中央凹周围细胞的横向移位以及神经节细胞层中移位无长突细胞的存在而变得复杂。我们现在通过GABA免疫组织化学和神经节细胞的逆行变性鉴定出了移位无长突细胞。通过从连续切片重建中央凹，我们能够比较视锥细胞、视锥细胞蒂和神经节细胞的密度；通过这种方式，我们发现每个中央凹视锥细胞有三个以上的神经节细胞。在中央视网膜和周边视网膜之间，神经节细胞密度变化了1000 - 2000倍，这在皮质放大倍数的估计范围内。因此，无需假定在膝状体和/或视觉皮层中中央凹有选择性放大。
