Muscat Louise, Huberman Andrew D, Jordan Cynthia L, Morin Lawrence P
Graduate Program in Neurobiology and Behavior, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
J Comp Neurol. 2003 Nov 24;466(4):513-24. doi: 10.1002/cne.10894.
The hamster suprachiasmatic nucleus (SCN), site of the circadian clock, has been thought to be equally and completely innervated by each retina. This issue was studied in animals that had received an injection of the tracer cholera toxin subunit B (CTb) conjugated to Alexa 488 into the vitreous of one eye, with CTb-Alexa 594 injected into the other. Retinal projections to the SCN and other nuclei of the circadian system were simultaneously evaluated by using confocal laser microscopy. Each retina provides completely overlapping terminal fields throughout each SCN. Although SCN innervation by the contralateral retina is slightly denser than that from the ipsilateral retina, there are distinct SCN regions where input from one side is predominant, but not exclusive. A dense terminal field from the contralateral retina encompasses, and extends dorsally beyond, the central SCN subnucleus identified by calbindin-immunoreactive neurons. Surrounding the dense terminal field, innervation is largely derived from the ipsilateral retina. The densest terminal field in the intergeniculate leaflet is from the contralateral retina, which completely overlaps the ipsilateral projection. Most nuclei of the pretectum receive innervation largely, but not solely, from the contralateral retina, although the olivary pretectal nucleus has very dense patches of innervation derived exclusively from one retina or the other. Retina-dependent variation in terminal field density within the three closely examined nuclei may indicate areas of specialized function not previously appreciated. This issue is discussed in the context of the melanopsin-containing retinal ganglion cell projections to several nuclei in the circadian visual system.
仓鼠的视交叉上核（SCN）是昼夜节律钟的所在部位，一直被认为接受来自每个视网膜的同等且完全的神经支配。在将与Alexa 488偶联的示踪剂霍乱毒素B亚基（CTb）注入一只眼睛的玻璃体，而将CTb-Alexa 594注入另一只眼睛的动物中研究了这个问题。通过共聚焦激光显微镜同时评估视网膜向SCN和昼夜节律系统其他核的投射。每个视网膜在整个SCN中提供完全重叠的终末场。虽然来自对侧视网膜的SCN神经支配比同侧视网膜的略密集，但存在不同的SCN区域，其中一侧的输入占主导，但并非唯一。来自对侧视网膜的密集终末场包围并背侧延伸超过由钙结合蛋白免疫反应性神经元识别的中央SCN亚核。在密集终末场周围，神经支配主要来自同侧视网膜。在膝间小叶中最密集的终末场来自对侧视网膜，它与同侧投射完全重叠。顶盖前区的大多数核主要但并非仅接受来自对侧视网膜的神经支配，尽管橄榄顶盖前核有非常密集的神经支配斑块，仅来自一侧视网膜。在所仔细检查的三个核内终末场密度的视网膜依赖性变化可能表明以前未被认识到的特殊功能区域。在含黑视蛋白的视网膜神经节细胞向昼夜节律视觉系统中几个核的投射的背景下讨论了这个问题。
