Joel D, Weiner I
Department of Psychology, Tel Aviv University, Ramat-Aviv, Tel Aviv, Israel.
Brain Res Brain Res Rev. 1997 Feb;23(1-2):62-78. doi: 10.1016/s0165-0173(96)00018-5.
The current view of basal ganglia organization holds that functionally corresponding subregions of the frontal cortex, basal ganglia and thalamus form several parallel segregated basal ganglia-thalamocortical circuits. In addition, this view states that striatal output reaches the basal ganglia output nuclei (the substantia nigra pars reticulata (SNR) and the internal segment of the globus pallidus (GPi)) via a 'direct' pathway, and via an 'indirect pathway' which traverses the external segment of the globus pallidus (GPe) and the subthalamic nucleus (STN). However, the topographical relationships of GPe and STN, and their topographical relationships with the basal ganglia-thalamocortical circuits are still unclear. The present work reviewed primate data on the topographical organization of STN afferents from GPe, and STN efferents to the pallidum, striatum and SNR, and examined these data with respect to a tripartite (motor, associative and limbic) functional subdivision of the striatum and pallidum. This examination indicated the following. (1) On the basis of its efferent connections, the STN may be divided into a motor and an associative territories, as well as a smaller limbic territory, each projecting to corresponding areas in the pallidum and striatum. (2) Efferents from GPe are in a position to contact subthalamic cells projecting to GPi/SNR, thus providing anatomical support for the existence of indirect pathways. (3) Moreover, given the tripartite division of the striatum, pallidum, and STN, the available data indicate the existence of indirect pathways connecting functionally corresponding subregions of the striatum, pallidum, and STN, as well as indirect pathways connecting functionally non-corresponding subregions. On the basis of the above we suggested that there may be two types of indirect pathways, one which terminates in the same subregion in GPi/SNR as the direct pathway arising from the same striatal subregion, and another which terminates in a different GPi/SNR subregion than the direct pathway arising from the same striatal subregion. We termed the former a 'closed indirect pathway' and the latter an 'open indirect pathway'. The application of these concepts to the surveyed data suggested the existence of three closed indirect pathways, each connecting the corresponding functional (motor, associative, and limbic) regions of the striatum, pallidum, STN, and SNR, as well as of two open indirect pathways, one connecting the associative striatum to the motor subregions of the basal ganglia, and the other connecting the associative striatum to the limbic subregions of the basal ganglia. While the organization of the closed indirect pathways fits the closed segregated arrangement of basal ganglia-thalamocortical circuitry, the organization of the open indirect pathways fits the recently suggested open interconnected scheme of basal ganglia thalamocortical circuitry. The clinical implications of this scheme for Huntington's disease are discussed.
目前关于基底神经节组织的观点认为，额叶皮质、基底神经节和丘脑在功能上相对应的亚区域形成了几个平行的、分离的基底神经节 - 丘脑皮质回路。此外，该观点指出，纹状体输出通过一条“直接”通路到达基底神经节输出核（黑质网状部（SNR）和苍白球内侧段（GPi）），并通过一条“间接”通路，该通路穿过苍白球外侧段（GPe）和底丘脑核（STN）。然而，GPe和STN的拓扑关系，以及它们与基底神经节 - 丘脑皮质回路的拓扑关系仍不清楚。本研究回顾了灵长类动物中关于STN来自GPe的传入纤维以及STN到苍白球、纹状体和SNR的传出纤维的拓扑组织的数据，并根据纹状体和苍白球的三分法（运动、联合和边缘）功能细分来检查这些数据。该检查表明了以下几点。（1）基于其传出连接，STN可分为一个运动区和一个联合区，以及一个较小的边缘区，每个区域投射到苍白球和纹状体中的相应区域。（2）GPe的传出纤维能够与投射到GPi/SNR的底丘脑细胞接触，从而为间接通路的存在提供了解剖学支持。（3）此外，考虑到纹状体、苍白球和STN的三分法，现有数据表明存在连接纹状体、苍白球和STN功能上相对应亚区域的间接通路，以及连接功能上不相对应亚区域的间接通路。基于上述情况，我们认为可能存在两种类型的间接通路，一种终止于GPi/SNR中与来自相同纹状体亚区域的直接通路相同的亚区域，另一种终止于与来自相同纹状体亚区域的直接通路不同的GPi/SNR亚区域。我们将前者称为“闭合间接通路”，后者称为“开放间接通路”。将这些概念应用于所调查的数据表明存在三条闭合间接通路，每条通路连接纹状体、苍白球、STN和SNR的相应功能（运动、联合和边缘）区域，以及两条开放间接通路，一条连接联合纹状体与基底神经节的运动亚区域，另一条连接联合纹状体与基底神经节的边缘亚区域。虽然闭合间接通路的组织符合基底神经节 - 丘脑皮质回路的闭合分离排列，但开放间接通路的组织符合最近提出的基底神经节丘脑皮质回路的开放互连模式。本文讨论了该模式对亨廷顿病的临床意义。
