Rieck R W, Carey R G
J Comp Neurol. 1985 Apr 8;234(2):137-54. doi: 10.1002/cne.902340202.
The present study demonstrates the organization of a thalamocortical projecting system which terminates within layer I of the visual cortex in the hooded rat. Horseradish peroxidase (HRP) injections restricted to layer I resulted in retrograde labeling of large and medium-sized multipolar and fusiform neurons that are located within the ventromedial (VM) nucleus and a dorsomedial subunit of the ventral anterolateral nucleus (VAL). Retrograde cellular labeling also occurs within the anteromedial nucleus (AM) following these injections. After restriction of HRP injections to layer I, peroxidase labeling was not found within neurons of the classically defined intralaminar system, i.e., central medial, paracentral, and central lateral nuclei, or within the rostral continuations of the intralaminar system. Since the VM, dorsomedial VAL, and AM nuclei are directly adjacent to portions of the internal medullary lamina, we refer to this amalgam of rostral thalamic nuclei that project to layer I as the "paralaminar" system. We also provide cytoarchitectonic criteria that can be used to distinguish three separate subdivisions within the VAL complex, including that portion of the VAL which is part of the "paralaminar" system. In contrast, when control injections of WGA-HRP are placed within either the cellular supragranular or infragranular layers of the visual cortex, no appreciable number of neurons are labeled within the VM, VAL, or AM.
本研究展示了一种丘脑皮质投射系统的组织结构，该系统终止于有头罩大鼠视觉皮质的第I层。将辣根过氧化物酶（HRP）注射局限于第I层，导致位于腹内侧（VM）核和腹前外侧核（VAL）背内侧亚单位内的大型和中型多极神经元及梭形神经元出现逆行标记。在这些注射后，前内侧核（AM）内也出现逆行细胞标记。将HRP注射局限于第I层后，在经典定义的板内核系统的神经元内，即中央内侧核、中央旁核和中央外侧核，或在板内核系统的嘴侧延续部分内，未发现过氧化物酶标记。由于VM核、VAL背内侧核和AM核直接毗邻内髓板的部分区域，我们将这种投射至第I层的嘴侧丘脑核的组合称为“板旁”系统。我们还提供了细胞构筑学标准，可用于区分VAL复合体中的三个独立亚区，包括作为“板旁”系统一部分的VAL部分。相比之下，当将WGA-HRP对照注射置于视觉皮质的细胞颗粒上层或颗粒下层时，VM核、VAL核或AM核内没有明显数量的神经元被标记。
