Flaherty A W, Graybiel A M
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
J Neurosci. 1993 Aug;13(8):3222-37. doi: 10.1523/JNEUROSCI.13-08-03222.1993.
The basal ganglia act through direct and indirect striatopallidal output pathways that have different effects on cortical activity. This division has been proposed to underlie the fundamental distinction between hyperkinetic and hypokinetic movement disorders such as Parkinson's disease and Huntington's disease. Evidence to date does not favor a relationship between this dual organization and the division of the striatum into striosome and matrix compartments. However, the possibility has been raised that the division of striatopallidal output paths reflects a compartmentalization of the matrix itself into clusters of different striatopallidal projection neurons. We directly tested this hypothesis in squirrel monkeys by comparing the distributions of striatal output neurons retrogradely labeled from the two pallidal segments. Striatopallidal neurons labeled by small injections confined to either the external pallidum (GPe) or the internal pallidum (GPi) formed small clusters ("matrisomes") in the matrix compartment of the putamen. However, contrary to previous predictions, labeled matrisomes projecting to GPe were not systematically separated from those projecting to GPi. They could overlap extensively, and within individual matrisomes GPe-projecting neurons and GPi-projecting neurons were extensively intermixed. Double-retrograde labeling analysis in single sections demonstrated that only 2.1 +/- 2.7% of labeled striatal neurons were doubly labeled from both GPe and GPi--a number not significantly different from zero. GPe-projecting and GPi-projecting neurons in the putamen also differed sharply in their expression of enkephalin-like immunoreactivity: 71.3 +/- 7.6% of the neurons labeled by GPe injections were enkephalin positive, in contrast to 10.0 +/- 3.6% of the neurons labeled by GPi injections. These results suggest that in the primate, populations of striatopallidal output neurons are grouped in clusters in the matrix, but that individual neurons in any given cluster project either to GPe or to GPi. Matrisomal clustering may thus coordinate signals sent into the direct and indirect pathways of the basal ganglia from distributed populations of projection neurons in the striatum.
基底神经节通过对皮质活动有不同影响的直接和间接纹状体苍白球输出通路发挥作用。有人提出这种划分是运动亢进和运动减退性运动障碍（如帕金森病和亨廷顿病）之间根本区别的基础。迄今为止的证据并不支持这种双重组织与纹状体分为纹状体小体和基质区室之间的关系。然而，有人提出纹状体苍白球输出路径的划分反映了基质本身划分为不同纹状体苍白球投射神经元的簇。我们通过比较从两个苍白球节段逆行标记的纹状体输出神经元的分布，在松鼠猴中直接检验了这一假设。局限于外侧苍白球（GPe）或内侧苍白球（GPi）的小注射标记的纹状体苍白球神经元在壳核的基质区室中形成小簇（“基质小体”）。然而，与先前的预测相反，投射到GPe的标记基质小体与投射到GPi的标记基质小体没有系统地分开。它们可能广泛重叠，并且在单个基质小体中，投射到GPe的神经元和投射到GPi的神经元广泛混合。单节段的双重逆行标记分析表明，只有2.1±2.7%的标记纹状体神经元同时被GPe和GPi双重标记——这个数字与零没有显著差异。壳核中投射到GPe和投射到GPi的神经元在脑啡肽样免疫反应性表达上也有很大差异：GPe注射标记的神经元中有71.3±7.6%脑啡肽呈阳性，而GPi注射标记的神经元中只有10.0±3.6%呈阳性。这些结果表明，在灵长类动物中，纹状体苍白球输出神经元群体在基质中聚集成簇，但任何给定簇中的单个神经元要么投射到GPe，要么投射到GPi。因此，基质小体聚集可能协调从纹状体中分布的投射神经元群体发送到基底神经节直接和间接通路的信号。
