Bevan M D, Clarke N P, Bolam J P
Medical Research Council Anatomical Neuropharmacology Unit and University Department of Pharmacology, Oxford OX1 3TH, United Kingdom.
J Neurosci. 1997 Jan 1;17(1):308-24. doi: 10.1523/JNEUROSCI.17-01-00308.1997.
To determine the principles of synaptic innervation of neurons in the entopeduncular nucleus and subthalamic nucleus by neurons of functionally distinct regions of the pallidal complex, double anterograde labeling was carried out at both light and electron microscopic levels in the rat. Deposits of the anterograde tracers Phaseolus vulgaris-leucoagglutinin and biotinylated dextran amine were placed in different functional domains of the pallidal complex in the same animals. The tracer deposits in the ventral pallidum and the globus pallidus gave rise to GABA-immunopositive projections to the entopeduncular nucleus, the subthalamic nucleus, and the more medial lateral hypothalamus that were largely segregated but overlapped at the interface between the two fields of projection. In these regions the proximal parts of individual neurons in the entopeduncular nucleus, lateral hypothalamus, and subthalamic nucleus received synaptic input from terminals derived from both the ventral pallidum and the globus pallidus. Furthermore, the analysis of the afferent synaptic input to the dendrites of neurons in the subthalamic nucleus that cross functional boundaries of the nucleus defined by the pallidal inputs, revealed that terminals with the morphological and neurochemical characteristics of those derived from the pallidal complex make synaptic contact with all parts of the dendritic tree, including distal regions. It is concluded that functionally diverse information carried by the descending projections of the pallidal complex is synaptically integrated by neurons of the entopeduncular nucleus, lateral hypothalamus, and subthalamic nucleus by two mechanisms. First, neurons located at the interface between functionally distinct, but topographically adjacent, projections could integrate diverse information by means of the synaptic convergence at the level of the cell body and proximal dendrites. Second, because the distal dendrites of neurons in the subthalamic nucleus receive input from the pallidum, those that extend across two distinct domains of pallidal input could also provide the morphological basis of integration.
为了确定苍白球复合体不同功能区的神经元对脚内核和底丘脑核神经元的突触支配原则，在大鼠中进行了光镜和电镜水平的双重顺行标记。将顺行示踪剂菜豆白细胞凝集素和生物素化葡聚糖胺注入同一动物苍白球复合体的不同功能区。腹侧苍白球和苍白球中的示踪剂沉积产生了向脚内核、底丘脑核和下丘脑内侧更外侧区域的GABA免疫阳性投射，这些投射在很大程度上是分开的，但在两个投射区域的界面处重叠。在这些区域，脚内核、下丘脑外侧和底丘脑核中单个神经元的近端部分接受来自腹侧苍白球和苍白球终末的突触输入。此外，对底丘脑核中跨越由苍白球输入所定义的核功能边界的神经元树突的传入突触输入分析表明，具有苍白球复合体来源的形态和神经化学特征的终末与树突的所有部分，包括远端区域，形成突触联系。得出的结论是，苍白球复合体下行投射携带的功能多样的信息通过两种机制在脚内核、下丘脑外侧和底丘脑核的神经元中进行突触整合。首先，位于功能不同但在地形上相邻的投射之间界面处的神经元可以通过细胞体和近端树突水平的突触汇聚来整合多样的信息。其次，由于底丘脑核中神经元的远端树突接受苍白球的输入，那些延伸穿过两个不同苍白球输入区域的树突也可以提供整合的形态学基础。
