Lomber S G, Payne B R, Cornwell P, Pearson H E
Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts 02118.
J Comp Neurol. 1993 Dec 15;338(3):432-57. doi: 10.1002/cne.903380308.
The purpose of the present study was to determine the pattern and density of retinal projections to the dorsal lateral geniculate nucleus (dLGN) following ablation of visual cortical areas in developing cats of different postnatal ages and in mature cats. The terminations of retinal projections to the dLGN were evaluated following the injection of tritiated amino acids into one eye. Regardless of age, a visual cortical ablation of areas 17 and 18 induces massive death of neurons within the regions of the dLGN that are linked topographically to the cortical areas removed. However, the pattern of retinal projections to these degenerated regions of the dLGN differs depending upon whether the cortical lesion is incurred early in postnatal life or in adulthood. Following ablation on the day of birth (P1), virtually all surviving cells were found in the C-complex of dLGN with only a token number in the A-laminae. Correspondingly, retinal projections were maintained to the C-complex of the nucleus and were barely detectable in the degenerated A-laminae. However, in cats in which areas 17 and 18 had been removed in adulthood (> or = 6 months of age) retinal projections were maintained to the A-laminae even though nearly all neurons in those laminae had degenerated. Moreover, a subgroup of animals that incurred area 17 and 18 ablations at P1 showed that the modification of retinal projections to the A-laminae occurs within the first postnatal month, and an additional subgroup showed that retinal projections become increasingly resistant to the degenerative events in the dLGN that follow ablation of areas 17 and 18 at progressively older ages during the first postnatal month. Furthermore, retinal inputs also respond, in an age-dependent way, to degeneration of neurons in the C-complex induced by extension of the cortical ablation to include extrastriate visual areas.
本研究的目的是确定在不同出生后年龄的发育中猫以及成年猫视觉皮层区域被切除后，视网膜向背外侧膝状核（dLGN）投射的模式和密度。在将氚标记氨基酸注入一只眼睛后，评估视网膜向dLGN投射的终末。无论年龄如何，对17区和18区的视觉皮层切除都会导致dLGN中与被切除皮层区域存在拓扑连接的区域内大量神经元死亡。然而，视网膜向dLGN这些退化区域的投射模式因皮层损伤是在出生后早期还是成年期发生而有所不同。在出生当天（P1）进行切除后，几乎所有存活细胞都位于dLGN的C复合体中，A板层中只有少量细胞。相应地，视网膜投射维持到该核的C复合体，而在退化的A板层中几乎检测不到。然而，在成年期（≥6个月龄）切除17区和18区的猫中，即使这些板层中的几乎所有神经元都已退化，视网膜投射仍维持到A板层。此外，在P1时切除17区和18区的一组动物显示，视网膜向A板层投射的改变发生在出生后的第一个月内，另一组动物显示，在出生后的第一个月内，随着年龄的增长，视网膜投射对17区和18区切除后dLGN中的退化事件越来越有抵抗力。此外，视网膜输入也以年龄依赖的方式对因皮层切除扩展至包括纹外视觉区域而导致的C复合体中神经元的退化做出反应。
