Carey R G, Neal T L
Brain Res. 1986 Oct 29;386(1-2):155-68. doi: 10.1016/0006-8993(86)90152-6.
We previously described the existence of reciprocal connections between the dorsal claustrum and striate cortex in the tree shrew, Tupaia glis. These projections were found to originate and terminate in a distinct topographic manner within the mid region of the upper portion of the dorsal claustrum. In this investigation, we examined the afferent and efferent projections between the claustrum and the lateral intermediate nucleus (Li) of the visual thalamus using small electrophoretic injections of anterograde and/or retrograde tracers (horseradish peroxidase, wheat germ agglutinin/horseradish peroxidase, or tritiated amino acids) into the claustrum, as well as the Li. Following tracer injections in the dorsal claustrum, labeled cells and/or terminal grains were found throughout the Li, except at the more caudal levels where the activity was confined to the lateral and medial borders. Tracer injections within the same nuclear region of the dorsal thalamus confirmed the existence of reciprocal projections between the Li and the claustrum. Following anterograde tracer injections, labeled terminals were found only within the most ventral zone of the dorsal claustrum--the 'hilum'; while retrograde tracer injections, produced labeled cells principally along the outer margins of the claustrum, including the hilum and tended to encapsulate the nucleus at all levels. Both sets of labeled activity were found to extend in this specific fashion over the majority of the dorsal claustrum, but appeared not to overlap with regions interconnected with striate cortex. These results thus suggest that the claustrum is capable of exerting a neural influence on cortex directly as well as indirectly via the visual thalamus. However, since the thalamic projection terminates in a claustral region not known to project to visual cortex, it is uncertain what function such projections have within the claustrum. It is possible that since Li receives ascending projections from the pretectum and superior colliculus, that it provides a multisensory input to the claustrum for relay onto areas outside of primary visual cortex.
我们之前描述过，在树鼩（笔尾树鼩）中，背侧屏状核与纹状皮层之间存在相互连接。这些投射被发现以上下分明的拓扑方式起始并终止于背侧屏状核上部的中间区域。在本研究中，我们使用向屏状核以及外侧中间核（Li）微量电泳注射顺行和/或逆行示踪剂（辣根过氧化物酶、小麦胚凝集素/辣根过氧化物酶或氚标记氨基酸）的方法，研究了屏状核与视觉丘脑外侧中间核（Li）之间的传入和传出投射。在背侧屏状核注射示踪剂后，在整个外侧中间核（Li）均发现了标记细胞和/或终末颗粒，但在更靠尾侧的水平，活性局限于外侧和内侧边界。在背侧丘脑相同核区域内注射示踪剂证实了外侧中间核（Li）与屏状核之间存在相互投射。顺行示踪剂注射后，标记终末仅见于背侧屏状核最腹侧区域——“门区”；而逆行示踪剂注射则主要在屏状核外缘产生标记细胞，包括门区，并在各个水平倾向于包裹该核。两组标记活性均以这种特定方式延伸至背侧屏状核的大部分区域，但似乎不与与纹状皮层相互连接的区域重叠。这些结果因此表明，屏状核能够直接以及通过视觉丘脑间接对皮层施加神经影响。然而，由于丘脑投射终止于屏状核中一个未知是否投射至视觉皮层的区域，因此尚不确定这些投射在屏状核内具有何种功能。有可能由于外侧中间核（Li）接受来自顶盖前区和上丘的上行投射，它为屏状核提供多感觉输入以便中继至初级视觉皮层以外的区域。
