Lavoie B, Parent A
Centre de Recherche en Neurobiologie, Hôpital de l'Enfant-Jésus, Québec, Canada.
J Comp Neurol. 1994 Jun 8;344(2):210-31. doi: 10.1002/cne.903440204.
The efferent projections of the pedunculopontine nucleus (PPN) to the basal ganglia have been studied in the squirrel monkey (Saimiri sciureus) with [3H]leucine and Phaseolus vulgaris-leucoagglutinin (PHA-L) as anterograde tracers. Following unilateral injections of [3H]leucine or PHA-L in the central portion of the PPN, numerous autoradiographic linear profiles or PHA-L-labeled fibers ascend to the forebrain, both ipsilaterally and contralaterally. These fibers form a compact bundle that courses in the central portion of the mesopontine tegmentum. At rostral mesencephalic levels, this bundle splits into ventromedial and dorsolateral fascicles that arborize in basal ganglia and thalamic nuclei, respectively. The substantia nigra and the subthalamic nucleus are by far the most densely innervated structures of the basal ganglia. In these two nuclei, labeled fibers arborize profusely ipsilaterally and less abundantly contralaterally. The labeled fibers in the substantia nigra are thin and varicose and arborize almost exclusively in the pars compacta, where they closely surround the soma and proximal dendrites of dopaminergic neurons. In the subthalamic nucleus, labeled fibers are also thin and appear to contact more than one neuron along their course. Numerous labeled fibers also occur in the pallidal complex, where they arborize most profusely in the internal segment. Several thick, labeled fibers oriented dorsolaterally in the pallidal complex give rise to thinner fibers that closely surround the soma and proximal dendrites of pallidal neurons. Some labeled fibers are also scattered in the striatum. These fibers abound in the peripallidal and ventral portions of the putamen, are more sparsely distributed in the remaining portion of the putamen as well as in the caudate nucleus, and are virtually absent in the ventral striatum. These results reveal that the PPN gives rise to a massive and highly ordered innervation of the basal ganglia in the squirrel monkey. This nucleus may thus act as an important relay in the basal ganglia circuitry in primates.
利用[³H]亮氨酸和菜豆白细胞凝集素（PHA-L）作为顺行示踪剂，在松鼠猴（Saimiri sciureus）中研究了脚桥核（PPN）向基底神经节的传出投射。在PPN中央部分单侧注射[³H]亮氨酸或PHA-L后，大量放射自显影线性轮廓或PHA-L标记的纤维向同侧和对侧的前脑上升。这些纤维形成一个紧密的束，在脑桥中脑被盖的中央部分走行。在中脑嘴侧水平，这个束分裂为腹内侧和背外侧束，分别在基底神经节和丘脑核中分支。黑质和丘脑底核是基底神经节中接受神经支配最密集的结构。在这两个核中，标记纤维主要在同侧大量分支，在对侧分支较少。黑质中的标记纤维细且有曲张，几乎只在致密部分支，它们紧密围绕多巴胺能神经元的胞体和近端树突。在丘脑底核中，标记纤维也很细，并且在其走行过程中似乎与不止一个神经元接触。苍白球复合体中也有许多标记纤维，它们在内侧段分支最丰富。苍白球复合体中一些向背外侧走行的粗标记纤维发出较细的纤维，紧密围绕苍白球神经元的胞体和近端树突。一些标记纤维也散布在纹状体中。这些纤维在壳核的周围苍白球和腹侧部分大量存在，在壳核的其余部分以及尾状核中分布较稀疏，在腹侧纹状体中几乎不存在。这些结果表明，PPN对松鼠猴的基底神经节产生大量且高度有序的神经支配。因此，这个核可能在灵长类动物的基底神经节回路中起到重要的中继作用。
