Selemon L D, Goldman-Rakic P S
Section of Neuroanatomy, Yale University School of Medicine, New Haven, Connecticut 06510.
J Comp Neurol. 1990 Jul 15;297(3):359-76. doi: 10.1002/cne.902970304.
The topography and interrelationship of striatofugal neurons have been examined using a double retrograde tracing paradigm to label striatopallidal and striatonigral neurons in the same neostriatum. The rostral globus pallidus and the rostral substantia nigra in the same hemisphere were injected simultaneously with fluorescent tracers in three monkeys. In addition, the caudal globus pallidus and the caudal substantia nigra were injected separately in a fourth and fifth monkey with a fluorescent dye and wheat germ agglutinin-horseradish peroxidase (WGA-HRP), respectively. Digitized plots of fluorescent dye-labeled neurons revealed that large numbers of striatonigral projection neurons lie within both neostriatal nuclei, i.e., the caudate and putamen. Similarly, neurons innervating the globus pallidus were found in both caudate and putamen. The distribution of retrogradely labeled neurons observed was consistent with the topography of striatofugal projections that has been described previously, i.e., the rostrocaudal and mediolateral axes of the neostriatum are preserved in the striatopallidal and striatonigral projections (e.g., Szabo, '62, '67, '70, '72) and the dorsoventral axis is inverted in the projection of the neostriatum onto the nigra but not in the striatopallidal projection (Nauta and Domesick, '79; Gerfen, '85). Analysis of cases in which striatonigral and striatopallidal neurons were present in large numbers within the same region of the neostriatum disclosed that the two populations are intermingled such that small clusters of striatopallidal neurons are surrounded by striatonigral neurons and vice versa. The clustered arrangement of striatofugal neurons observed in the fluorescent cases was unambiguous in a case in which HRP was injected into the caudal substantia nigra. In this case, both anterogradely labeled terminals and retrogradely labeled neurons exhibited a striking, compartmental-like distribution in the posterior putamen. Our observations indicate that the matrix compartment of the neostriatum is comprised of a patchwork of interposed clusters of nigral and pallidal efferent neurons. We hypothesize that these clusters of efferent neurons may direct interdigitated cortical inputs into distinct nigro- and pallido-thalamic pathways. In view of the parallel nature of processing throughout the basal ganglia, it appears that convergence of these segregated nigral and pallidal loops must occur at the cortical level where prefrontal and premotor targets of the basal ganglia are interconnected via corticocortical projections (Selemon and Goldman-Rakic, '88).
利用双重逆行追踪范式来标记同一新纹状体内的纹状体苍白球和纹状体黑质神经元，以此研究了纹状体传出神经元的拓扑结构及其相互关系。在三只猴子的同一半球中，同时向嘴侧苍白球和嘴侧黑质注射了荧光示踪剂。此外，在第四只和第五只猴子中，分别向尾侧苍白球和尾侧黑质注射了荧光染料和小麦胚凝集素 - 辣根过氧化物酶（WGA - HRP）。荧光染料标记神经元的数字化图谱显示，大量纹状体黑质投射神经元位于两个新纹状体核团内，即尾状核和壳核。同样，在尾状核和壳核中均发现了支配苍白球的神经元。观察到的逆行标记神经元的分布与先前描述的纹状体传出投射的拓扑结构一致，即新纹状体的前后轴和中外侧轴在纹状体苍白球和纹状体黑质投射中得以保留（例如，Szabo，1962年、1967年、1970年、1972年），并且新纹状体到黑质的投射中背腹轴是倒置的，但在纹状体苍白球投射中并非如此（Nauta和Domesick，1979年；Gerfen，1985年）。对新纹状体同一区域内大量存在纹状体黑质和纹状体苍白球神经元的病例分析表明，这两种神经元群体相互交织，以至于小群的纹状体苍白球神经元被纹状体黑质神经元包围，反之亦然。在向尾侧黑质注射HRP的病例中，荧光病例中观察到的纹状体传出神经元的簇状排列清晰可见。在这个病例中，顺行标记的终末和逆行标记的神经元在后部壳核中均呈现出显著的、类似分区的分布。我们的观察结果表明，新纹状体的基质区由插入的黑质和苍白球传出神经元簇组成的拼凑物构成。我们推测，这些传出神经元簇可能将相互交叉的皮质输入引导至不同的黑质 - 丘脑和苍白球 - 丘脑通路。鉴于整个基底神经节处理过程的平行性质，似乎这些分离的黑质和苍白球环路的汇聚必定发生在皮质水平，在该水平基底神经节的前额叶和运动前区靶点通过皮质 - 皮质投射相互连接（Selemon和Goldman - Rakic，1988年）。
