Deniau J M, Chevalier G
Université Pierre et Marie Curie, Département des Neurosciences de la Vision, Institut des Neurosciences, U.A. 1199, Paris, France.
Neuroscience. 1992;46(2):361-77. doi: 10.1016/0306-4522(92)90058-a.
As a major output station of the basal ganglia, the pars reticulata of the substantia nigra has stimulated much interest. In the past two decades there has been a growing body of evidence for a partition of this structure into separate channels to express the striatal processing. To further our knowledge on the functional partitioning of the rodent substantia nigra pars reticulata, the regional distribution of the nigral efferent cell groups that provide innervation of thalamus, colliculus and tegmentum has been detailed in rat using the wheatgerm agglutinin conjugated with horseradish peroxidase as an axonal tracer. To ensure a total visualization of the nigral efferent neurons we have, in a preliminary study, determined the total extent of the nigral terminal field in each of the nigral target structures using the anterograde transport of wheatgerm agglutinin-horseradish peroxidase and Phaseolus vulgaris leucoagglutinin. At variance with the classical view that nigral cells innervating distinct target structures form functionally distinct subnuclei, the results suggest a nigral compartmentation that rather relies upon specific associations of efferent cell groups. As disclosed, these associations are specified by topographic rules and spatially ordered in a series of curved laminae enveloping an excentrated dorsolateral core. In this onion-like model of the substantia nigra pars reticulata, each lamella defines an associative unit composed of a set of neurons innervating particular loci of thalamus, colliculus and/or tegmentum. This lamellar partitioning bestows the ability upon the substantia nigra to dispatch the striatal outflow via parallel and divergent channels to functionally associated target areas in thalamus and brainstem.
作为基底神经节的主要输出站，黑质网状部引起了人们极大的兴趣。在过去的二十年里，越来越多的证据表明，该结构可分为不同的通道来表达纹状体的处理过程。为了进一步了解啮齿动物黑质网状部的功能分区，利用与辣根过氧化物酶结合的小麦胚芽凝集素作为轴突示踪剂，详细研究了大鼠黑质传出细胞群在丘脑、丘系和被盖的神经支配区域分布。为了确保完全可视化黑质传出神经元，在一项初步研究中，我们利用小麦胚芽凝集素-辣根过氧化物酶和菜豆白细胞凝集素的顺行运输，确定了黑质各靶结构中黑质终末场的总体范围。与经典观点不同，经典观点认为支配不同靶结构的黑质细胞形成功能上不同的亚核，而结果表明黑质的分隔更依赖于传出细胞群的特定关联。如所揭示的，这些关联由地形规则指定，并在围绕偏心背外侧核心的一系列弯曲薄片中按空间顺序排列。在这种黑质网状部的洋葱样模型中，每个薄片定义了一个关联单元，该单元由一组支配丘脑、丘系和/或被盖特定位点的神经元组成。这种层状分区赋予黑质通过平行和发散通道将纹状体输出发送到丘脑和脑干中功能相关靶区域的能力。
