Hayes N L, Rustioni A
Exp Brain Res. 1981;41(2):89-107. doi: 10.1007/BF00236598.
Single and double retrograde tracer techniques were employed in cats to investigate: (1) the topographical relationships between supraspinal neurons projecting to either the brachial or lumbosacral enlargement, (2) the distribution and relative frequency of single supraspinal neurons which project to both enlargements by means of axonal branching. In one group of cats large injections of horseradish peroxidase (HRP) were made throughout either the brachial or lumbosacral enlargement. The results from these experiments support recent observations on the multiplicity of brainstem centers giving origin to descending spinal pathways and provide evidence for a population of corticospinal neurons in area 6. In a second set of experiments, HRP was injected in one enlargement, and 3H-apo-HRP (enzymatically inactive) was injected in the other enlargement. Relatively large numbers of neurons with collateral projections to both enlargements (double-labeled) were observed in the medullary and pontine reticular formation, the medial and inferior vestibular nuclei bilaterally, the ipsilateral lateral vestibular nucleus, Edinger-Westphal nucleus, caudal midline raphe nuclei and nuclear regions surrounding the brachium conjunctivum. By contrast, double-labeled neurons were infrequently observed in the red nucleus and sensorimotor cortex, contralateral to the injections. In the red nucleus, lateral vestibular nucleus and sensorimotor cortex, neurons projecting to the brachial enlargement were largely segregated topographically from neurons projecting to the lumbosacral enlargement. However, there was some overlap, and double-labeled neurons were consistently observed within the region of overlap. In the sensorimotor cortex, the overlap between brachial- and lumbar-projecting neurons was most prominent in areas 4 and 3a, along the cruciate sulcus, but also involved other cytoarchitectonic regions in the medial aspect of the hemisphere.
（1）投射到臂丛或腰骶膨大的脊髓上神经元之间的拓扑关系；（2）通过轴突分支投射到两个膨大的单个脊髓上神经元的分布和相对频率。在一组猫中，在整个臂丛或腰骶膨大处大量注射辣根过氧化物酶（HRP）。这些实验的结果支持了最近关于起源于下行脊髓通路的脑干中心多样性的观察，并为6区的皮质脊髓神经元群体提供了证据。在第二组实验中，在一个膨大处注射HRP，在另一个膨大处注射3H-脱辅基-HRP（无酶活性）。在延髓和脑桥网状结构、双侧内侧和下前庭核、同侧外侧前庭核、动眼神经副核、尾侧中线缝核以及结合臂周围的核区域中观察到相对大量的向两个膨大发出侧支投射的神经元（双标记）。相比之下，在注射对侧的红核和感觉运动皮层中很少观察到双标记神经元。在红核、外侧前庭核和感觉运动皮层中，投射到臂丛膨大的神经元在拓扑学上与投射到腰骶膨大的神经元基本分离。然而，存在一些重叠，并且在重叠区域内始终观察到双标记神经元。在感觉运动皮层中，投射到臂丛和腰骶的神经元之间的重叠在4区和3a区沿着十字沟最为明显，但也涉及半球内侧的其他细胞构筑区域。
