van Groen T, Wyss J M
Department of Cell Biology and Anatomy, University of Alabama, Birmingham 35294.
J Comp Neurol. 1990 Oct 22;300(4):593-606. doi: 10.1002/cne.903000412.
Although the retrosplenial granular a cortex (Rga) is situated in a critical position between the hippocampal formation and the neocortex, few studies have examined its connections. The present experiments use both retrograde and anterograde tracing techniques to characterize the afferent and efferent connections of Rga. Cortical projections to Rga originate in the ipsilateral area infraradiata, the retrosplenial agranular and granular b cortices, the ventral subiculum, and the contralateral Rga. Subcortical projections originate in the claustrum, the diagonal band of Broca, the thalamus, the midbrain raphe nuclei, and the locus coeruleus. The thalamic projections to Rga originate mainly in the anterodorsal (AD) and laterodorsal (LD) nuclei with sparse projections arising in the anteroventral (AV) and reuniens nuclei. Each projection to Rga terminates in distinct layers of the cortex. The thalamic projection from AD terminates primarily in layers I, III, and IV of Rga, whereas the axons arising from the LD nucleus have a dense terminal plexus only in layer 1. The projections arising from the subiculum end predominantly in layer II, whereas the postsubiculum projects to layers I and III-V. Axons from the contralateral Rga form a dense terminal plexus in layers IV and V, with a smaller number of terminals in layers I and VI. Rga projects ipsilaterally to the AV and LD nuclei of the thalamus and to the anterior cingulate, retrosplenial agranular,a and postsubicular cortices. Contralaterally it projects to the retrosplenial agranular and Rga cortices. Rga projections to the thalamus terminate ipsilaterally in the dorsal part of LD and bilaterally in AV. Together, these data suggest that Rga integrates thalamic with limbic information.
尽管压后颗粒皮质（Rga）位于海马结构和新皮质之间的关键位置，但很少有研究对其连接进行过研究。本实验采用逆行和顺行示踪技术来描绘Rga的传入和传出连接。投射到Rga的皮质起源于同侧辐射下区、压后无颗粒皮质和颗粒b皮质、腹侧下托以及对侧Rga。皮质下投射起源于屏状核、布洛卡斜带、丘脑、中脑缝核和蓝斑。投射到Rga的丘脑主要起源于前背核（AD）和外侧背核（LD），在前腹核（AV）和连合核有稀疏投射。每条投射到Rga的纤维都终止于皮质的不同层。来自AD的丘脑投射主要终止于Rga的I、III和IV层，而来自LD核的轴突仅在第1层有密集的终末丛。来自下托的投射主要终止于II层，而后下托投射到I层和III - V层。来自对侧Rga的轴突在IV和V层形成密集的终末丛，在I和VI层有较少的终末。Rga同侧投射到丘脑的AV和LD核以及前扣带回、压后无颗粒皮质和后下托皮质。对侧则投射到压后无颗粒皮质和Rga皮质。Rga投射到丘脑的纤维同侧终止于LD的背侧部分，双侧终止于AV。这些数据共同表明，Rga整合了丘脑和边缘系统的信息。
