Chomsung Ranida D, Petry Heywood M, Bickford Martha E
Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky 40292, USA.
J Comp Neurol. 2008 Sep 1;510(1):24-46. doi: 10.1002/cne.21763.
Two pathways from the superior colliculus (SC) to the tree shrew pulvinar nucleus have been described, one in which the axons terminate in dense (or specific) patches and one in which the axon arbors are more diffusely organized (Luppino et al. [1988] J. Comp. Neurol. 273:67-86). As predicted by Lyon et al. ([2003] J. Comp. Neurol. 467:593-606), we found that anterograde labeling of the diffuse tectopulvinar pathway terminated in the acetylcholinesterase (AChE)-rich dorsal pulvinar (Pd), whereas the specific pathway terminated in the AChE-poor central pulvinar (Pc). Injections of retrograde tracers in Pd labeled non-gamma-aminobutyric acid (GABA)-ergic wide-field vertical cells located in the lower stratum griseum superficiale and stratum opticum of the medial SC, whereas injections in Pc labeled similar cells in more lateral regions. At the ultrastructural level, we found that tectopulvinar terminals in both Pd and Pc contact primarily non-GABAergic dendrites. When present, however, synaptic contacts on GABAergic profiles were observed more frequently in Pc (31% of all contacts) compared with Pd (16%). Terminals stained for the type 2 vesicular glutamate transporter, a potential marker of tectopulvinar terminals, also contacted more GABAergic profiles in Pc (19%) compared with Pd (4%). These results provide strong evidence for the division of the tree shrew pulvinar into two distinct tectorecipient zones. The potential functions of these pathways are discussed.
从树鼩上丘（SC）到丘脑枕核的两条通路已被描述，一条通路中轴突终止于密集（或特定）的斑块，另一条通路中轴突分支的组织更为弥散（Luppino等人，[1988]《比较神经学杂志》273:67 - 86）。正如Lyon等人（[2003]《比较神经学杂志》467:593 - 606）所预测的，我们发现弥散性顶盖 - 丘脑枕通路的顺行标记终止于富含乙酰胆碱酯酶（AChE）的背侧丘脑枕（Pd），而特定通路终止于AChE含量低的中央丘脑枕（Pc）。在Pd注射逆行示踪剂标记了位于内侧SC浅层灰质下层和视层的非γ - 氨基丁酸（GABA）能宽视野垂直细胞，而在Pc注射标记了更外侧区域的类似细胞。在超微结构水平上，我们发现Pd和Pc中的顶盖 - 丘脑枕终末主要与非GABA能树突接触。然而，当存在时，与Pd（16%）相比，在Pc中观察到与GABA能形态的突触接触更频繁（占所有接触的31%）。用2型囊泡谷氨酸转运体染色的终末，这是顶盖 - 丘脑枕终末的一个潜在标记物，与Pd（4%）相比，在Pc中也与更多的GABA能形态接触（19%）。这些结果为将树鼩丘脑枕分为两个不同的顶盖接受区提供了有力证据。并讨论了这些通路的潜在功能。
