Coleman K A, Mitrofanis J
Sydney Institute of Biomedical Research, Department of Anatomy and Histology, University of Sydney, Sydney, Australia.
Eur J Neurosci. 1996 Feb;8(2):388-404. doi: 10.1111/j.1460-9568.1996.tb01222.x.
The visual sector of the reticular thalamic nucleus has come under some intense scrutiny over recent years, principally because of the key role that the nucleus plays in the processing of visual information. Despite this scrutiny, we know very little of how the connections between the reticular nucleus and the different areas of visual cortex and the different visual dorsal thalamic nuclei are organized. This study examines the patterns of reticular connections with the visual cortex and the dorsal thalamus in the rat, a species where the visual pathways have been well documented. Biotinylated dextran, an anterograde and retrograde tracer, was injected into different visual cortical areas [17; rostral 18a: presumed area AL: (anterolateral); caudal 18a: presumed area LM (lateromedial); rostral 18b: presumed area AM (anteromedial); caudal 18b: presumed area PM (posteromedial)] and into different visual dorsal thalamic nuclei (posterior thalamic, lateral geniculate nuclei), and the patterns of anterograde and retrograde labelling in the reticular nucleus were examined. From the cortical injections, we find that the visual sector of the reticular nucleus is divided into subsectors that each receive an input from a distinct visual cortical area, with little or no overlap. Further, the resulting pattern of cortical terminations in the reticular nucleus reflects largely the patterns of termination in the dorsal thalamus. That is, each cortical area projects to a largely distinct subsector of the reticular nucleus, as it does to a largely distinct dorsal thalamic nucleus. As with each of the visual cortical areas, each of the visual dorsal thalamic (lateral geniculate, lateral posterior, posterior thalamic) nuclei relate to a separate territory of the reticular nucleus, with little or no overlap. Each of these dorsal thalamic territories within the reticular nucleus receives inputs from one or more of the visual cortical areas. For instance, the region to the reticular nucleus that is labelled after an injection into the lateral geniculate nucleus encompasses the reticular regions which receive afferents from cortical areas 17, rostral 18b and caudal 18b. These results suggest that individual cortical areas may influence the activity of different dorsal thalamic nuclei through their reticular connections.
近年来，丘脑网状核的视觉部分受到了一些深入的研究，主要是因为该核在视觉信息处理中发挥着关键作用。尽管有这些研究，但我们对网状核与视觉皮层不同区域以及不同视觉背侧丘脑核之间的连接是如何组织的却知之甚少。本研究考察了大鼠中网状核与视觉皮层和背侧丘脑之间的连接模式，大鼠的视觉通路已有充分的文献记载。将生物素化葡聚糖（一种顺行和逆行示踪剂）注入不同的视觉皮层区域[17区；18a区前部：推测为AL区（前外侧）；18a区后部：推测为LM区（外侧内侧）；18b区前部：推测为AM区（前内侧）；18b区后部：推测为PM区（后内侧）]以及不同的视觉背侧丘脑核（丘脑后部、外侧膝状体核），并检查网状核中顺行和逆行标记的模式。从皮层注射实验中，我们发现网状核的视觉部分被分为不同的亚区，每个亚区都接收来自不同视觉皮层区域的输入，几乎没有重叠。此外，皮层在网状核中的终末模式在很大程度上反映了在背侧丘脑中的终末模式。也就是说，每个皮层区域投射到网状核的一个基本不同的亚区，就如同它投射到一个基本不同的背侧丘脑核一样。与每个视觉皮层区域一样，每个视觉背侧丘脑（外侧膝状体、丘脑外侧后部、丘脑后部）核都与网状核的一个独立区域相关，几乎没有重叠。网状核内的这些背侧丘脑区域中的每一个都接收来自一个或多个视觉皮层区域的输入。例如，向外侧膝状体核注射后在网状核中标记的区域包括从皮层17区、18b区前部和18b区后部接收传入纤维的网状区域。这些结果表明，单个皮层区域可能通过其网状连接影响不同背侧丘脑核的活动。
