Szmajda Brett A, Grünert Ulrike, Martin Paul R
National Vision Research Institute of Australia, Carlton, and the Department of Optometry and Vision Sciences, The University of Melbourne, Australia.
Vis Neurosci. 2005 Jul-Aug;22(4):395-404. doi: 10.1017/S0952523805224021.
We measured mosaic properties of midget and parasol ganglion cells in the retina of a New World monkey, the common marmoset Callithrix jacchus . We addressed the functional specialization of these populations for color and spatial vision, by comparing the mosaic of ganglion cells in dichromatic ("red-green color blind") and trichromatic marmosets. Ganglion cells were labelled by photolytic amplification of retrograde marker ("photofilling") following injections into the lateral geniculate nucleus, or by intracellular injection in an in vitro retinal preparation. The dendritic-field size, shape, and overlap of neighboring cells were measured. We show that in marmosets, both midget and parasol cells exhibit a radial bias, so that the long axis of the dendritic field points towards the fovea. The radial bias is similar for parasol cells and midget cells, despite the fact that midget cell dendritic fields are more elongated than are those of parasol cells. The dendritic fields of midget ganglion cells from the same (ON or OFF) response-type array show very little overlap, consistent with the low coverage of the midget mosaic in humans. No large differences in radial bias, or overlap, were seen on comparing retinae from dichromatic and trichromatic animals. These data suggest that radial bias in ganglion cell populations is a consistent feature of the primate retina. Furthermore, they suggest that the mosaic properties of the midget cell population are associated with high spatial resolution rather than being specifically associated with trichromatic color vision.
我们测量了一种新大陆猴——普通狨猴（Callithrix jacchus）视网膜中侏儒节细胞和伞状节细胞的镶嵌特性。通过比较二色性（“红绿色盲”）和三色性狨猴的节细胞镶嵌情况，我们探讨了这些细胞群体在颜色和空间视觉方面的功能特化。向外侧膝状体核注射后，通过逆行标记物的光解放大（“光填充”）对节细胞进行标记，或者在体外视网膜标本中进行细胞内注射来标记节细胞。测量了相邻细胞的树突野大小、形状和重叠情况。我们发现，在狨猴中，侏儒节细胞和伞状节细胞均表现出径向偏向，即树突野的长轴指向中央凹。尽管侏儒节细胞的树突野比伞状节细胞的更细长，但伞状节细胞和侏儒节细胞的径向偏向相似。来自相同（ON或OFF）反应类型阵列的侏儒节细胞的树突野几乎没有重叠，这与人类侏儒节细胞镶嵌的低覆盖率一致。在比较二色性和三色性动物的视网膜时，未发现径向偏向或重叠有很大差异。这些数据表明，节细胞群体的径向偏向是灵长类动物视网膜的一个一致特征。此外，这些数据还表明，侏儒节细胞群体的镶嵌特性与高空间分辨率相关，而不是与三色性颜色视觉特别相关。
