Parent M, Lévesque M, Parent A
Centre de recherche Université Laval Robert-Giffard, 2601, Chemin de la Canardière, Beauport, Québec, Canada, G1J 2G3.
J Comp Neurol. 2001 Oct 15;439(2):162-75. doi: 10.1002/cne.1340.
The axonal projections of the internal pallidum (GPi) in cynomolgus monkeys (Macaca fascicularis) were studied by labeling small pools of neurons with biotinylated dextran amine. Fifty-two axons were reconstructed entirely from serial sections with a camera lucida. Two types of projection neurons were identified in the GPi on the basis of their target sites. The abundant and centrally located type I neurons gave rise to a long axonal branch that descended directly to the pedunculopontine tegmental nucleus, where it arborized discretely. Other branches ascended to the thalamus and broke into 10-15 thinner collaterals that ran through most of the ventral anterior nucleus, where they terminated as typical plexuses. About half of these axons gave rise to collaterals that arborized in both components of the centre médian/parafascicular thalamic complex. The less numerous and peripherally located type II neurons had an axon that climbed the rostral thalamic pole, coursed along the stria medullaris, and arborized profusely within the lateral habenular nucleus, which stood out as the most densely innervated pallidal target. Some type II axons provided collaterals to the anterior thalamic nuclei. A small proportion of axons of both types had branches that crossed the midline and terminated in contralateral GPi target structures. Three-dimensional reconstruction showed that type I axons arborized principally along the sagittal plane. These data reveal that GPi neurons of type I act through a widely distributed axonal network upon thalamic and brainstem premotor neurons, whereas type II neurons act in a much more focused manner upon lateral habenular neurons.
通过用生物素化葡聚糖胺标记少量神经元池，研究了食蟹猴（猕猴）苍白球内侧部（GPi）的轴突投射。用明箱绘图仪从连续切片中完整重建了52条轴突。根据靶位点在GPi中鉴定出两种投射神经元。数量丰富且位于中央的I型神经元发出一条长轴突分支，直接向下延伸至脚桥被盖核，并在那里离散地分支。其他分支向上延伸至丘脑，分成10 - 15条较细的侧支，穿过大部分腹前核，并在那里形成典型的丛状终末。这些轴突中约一半发出侧支，在丘脑中央中核/束旁核复合体的两个部分都有分支。数量较少且位于外周的II型神经元有一条轴突，向上攀爬至丘脑嘴侧极，沿着髓纹走行，并在外侧缰核内大量分支，外侧缰核是苍白球最密集支配的靶区。一些II型轴突向丘脑前核提供侧支。两种类型的一小部分轴突有穿过中线并终止于对侧GPi靶结构的分支。三维重建显示，I型轴突主要沿矢状面分支。这些数据表明，I型GPi神经元通过广泛分布的轴突网络作用于丘脑和脑干的运动前神经元，而II型神经元则以更集中的方式作用于外侧缰核神经元。
