Sripanidkulchai K, Wyss J M
J Comp Neurol. 1986 Dec 8;254(2):143-65. doi: 10.1002/cne.902540202.
The topographic relationships between anterior thalamic neurons and their terminal projection fields in the retrosplenial cortex of the rat were characterized by experiments with the fluorescent dye retrograde labeling technique. The results demonstrate that the anterodorsal (DAD) and anteroventral (AV) nuclei project heavily to retrosplenial granular cortex (Rg) and to a lesser extent to retrosplenial agranular cortex (Rag). In contrast, the anteromedial (AM) and lateral dorsal (LD) nuclei project heavily to Rag and more lightly to Rg. Irrespective of terminal field in Rg or Rag, the neuronal cell bodies in AD and AV are organized topographically so that the neurons in the caudal part of each nucleus project to rostral retrosplenial cortex and the neurons in the rostral portion of each nucleus project to the caudal retrosplenial cortex. Further, the ventromedial AD and AV neurons project to rostral retrosplenial cortex, whereas dorsolateral neurons in both nuclei project to caudal retrosplenial cortex. LD neurons display a different topographic organization. The neurons in the medioventral part of LD project primarily to the rostral retrosplenial cortex, and the neurons in lateral LD project to the caudal retrosplenial cortex. This latter projection to the caudal retrosplenial cortex is also contributed to by neurons residing in the mediodorsal part of caudal LD. The neurons in AM that project to the retrosplenial cortex display less segregation than the AV, AD, or LD neurons. In all experiments, a number of neurons in the dorsal ventro-anterolateral nucleus were labeled by retrosplenial injections. The largest number of cells in this nucleus were labeled after Rag injections, and these were topographically organized such that the neurons projecting to the rostral Rag were located immediately deep to the internal medullary lamina, and the neurons projecting to the caudal Rag were more ventrally located. Very few thalamic neurons have axon collaterals to different areas of the retrosplenial cortex as shown by double labeling experiments. Together, these results demonstrate a highly organized thalamic projection to the retrosplenial cortex.
通过荧光染料逆行标记技术实验，对大鼠丘脑前核神经元与其在压后皮质的终末投射区之间的局部关系进行了表征。结果表明，丘脑前背核（DAD）和前腹核（AV）大量投射至压后颗粒皮质（Rg），并较少程度地投射至压后无颗粒皮质（Rag）。相反，丘脑前内侧核（AM）和背外侧核（LD）大量投射至Rag，而投射至Rg的程度较轻。无论投射至Rg还是Rag，AD和AV中的神经元胞体均按局部定位排列，使得每个核尾侧部分的神经元投射至压后皮质的嘴侧，而每个核嘴侧部分的神经元投射至压后皮质的尾侧。此外，AD和AV的腹内侧神经元投射至压后皮质的嘴侧，而两个核中的背外侧神经元投射至压后皮质的尾侧。LD神经元表现出不同的局部定位组织。LD中间腹侧部分的神经元主要投射至压后皮质的嘴侧，而外侧LD的神经元投射至压后皮质的尾侧。尾侧LD中间背侧部分的神经元也对压后皮质尾侧有这种投射。投射至压后皮质的AM神经元比AV、AD或LD神经元表现出的分离程度更低。在所有实验中，压后注射标记了背腹前外侧核中的一些神经元。该核中标记细胞数量最多的是在Rag注射后，这些细胞按局部定位排列，使得投射至嘴侧Rag的神经元紧邻内髓板深部，而投射至尾侧Rag的神经元位置更靠腹侧。如双重标记实验所示，很少有丘脑神经元有轴突侧支至压后皮质的不同区域。总之，这些结果表明丘脑至压后皮质的投射具有高度组织性。
