van Groen T, Wyss J M
Department of Cell Biology, University of Alabama, Birmingham 35294.
J Comp Neurol. 1992 Jan 8;315(2):200-16. doi: 10.1002/cne.903150207.
Although the retrosplenial dysgranular cortex (Rdg) is situated both physically and connectionally between the hippocampal formation and the neocortex, few studies have focused on the connections of Rdg. The present study employs retrograde and anterograde anatomical tracing methods to delineate the connections of Rdg. Each projection to Rdg terminates in distinct layers of the cortex. The thalamic projections to Rdg originate in the anterior (primarily the anteromedial), lateral (primarily the laterodorsal), and reuniens nuclei. Those from the anteromedial nucleus terminate predominantely in layers I and IV-VI, whereas the axons arising from the laterodorsal nucleus have a dense terminal plexus in layers I and III-IV. The cortical projections to Rdg originate primarily in the infraradiata, retrosplenial, postsubicular, and areas 17 and 18b cortices. The projections arising from visual areas 18b and 17 predominantly terminate in layer I of Rdg, axons from contralateral Rdg form a dense terminal plexus in layers I-IV, with a smaller number of terminals in layers V and VI, afferents from postsubiculum terminate in layers I and III-V, and the projection from infraradiata cortex terminates in layers I and V-VI. The efferent projections from Rdg are widespread. The major cortical projections from Rdg are to infraradiata, retrosplenial granular, area 18b, and postsubicular cortices. Subcortical projections from Rdg terminate primarily in the ipsilateral caudate and lateral thalamic nuclei and bilaterally in the anterior thalamic nuclei. The efferent projections from Rdg are topographically organized. Rostral Rdg projects to the dorsal infraradiata cortex and the rostral postsubiculum, while caudal Rdg axons terminate predominantely in the ventral infraradiata and the caudal postsubicular cortices. Caudal but not rostral Rdg projects to areas 17 and 18b of the cortex. The Rdg projections to the lateral and anterior nuclei also are organized along the rostral-caudal axis. Together, these data suggest that Rdg integrates thalamic, hippocampal, and neocortical information.
尽管压后颗粒下皮质（Rdg）在解剖位置和连接关系上均处于海马结构与新皮质之间，但很少有研究聚焦于Rdg的连接。本研究采用逆行和顺行解剖示踪方法来描绘Rdg的连接。每条投射至Rdg的纤维都终止于皮质的不同层。投射至Rdg的丘脑纤维起源于前核（主要是前内侧核）、外侧核（主要是背外侧核）和 reuniens 核。来自前内侧核的纤维主要终止于I层和IV - VI层，而来自背外侧核的轴突在I层和III - IV层有密集的终末丛。投射至Rdg的皮质纤维主要起源于辐射下皮质、压后皮质、后下托皮质以及17区和18b区皮质。来自视觉18b区和17区的投射主要终止于Rdg的I层，对侧Rdg的轴突在I - IV层形成密集的终末丛，在V层和VI层有较少的终末，来自后下托的传入纤维终止于I层和III - V层，辐射下皮质的投射终止于I层和V - VI层。Rdg的传出投射广泛。Rdg的主要皮质投射至辐射下皮质、压后颗粒皮质、18b区和后下托皮质。Rdg的皮质下投射主要终止于同侧尾状核和外侧丘脑核，双侧投射至前丘脑核。Rdg的传出投射呈拓扑学组织。Rdg的嘴侧部分投射至背侧辐射下皮质和嘴侧后下托，而尾侧Rdg的轴突主要终止于腹侧辐射下皮质和尾侧后下托皮质。尾侧而非嘴侧的Rdg投射至皮质的17区和18b区。Rdg向外侧核和前核的投射也沿嘴尾轴组织。总之，这些数据表明Rdg整合了丘脑、海马和新皮质的信息。
