Tolbert D L, Alisky J M, Clark B R
Francis and Doris Murphy Neuroanatomy Research Laboratory, St Louis University School of Medicine, Missouri 63104.
Neuroscience. 1993 Aug;55(3):755-74. doi: 10.1016/0306-4522(93)90440-q.
The topography of wheatgerm agglutinin-horseradish peroxidase/horseradish peroxidase-labeled mossy fiber terminals of lower thoracic-upper lumbar (T12-L3) spinal projections to the cerebellar anterior lobe was quantitatively analysed in adult rats. Computer-based image analysis mapped the orthogonal (parallel to the surface) distribution of labeled terminals in two-dimensional reconstructions of the unfoled anterior lobe cortex. The radial (perpendicular to the surface) distribution of terminals within the granule cell layer was mapped by computing whether the terminals were in either the outer- or inner-halves of this layer. The number of labeled terminals in each lobule was calculated. In the anterior lobe, lower thoracic-upper lumbar spinocerebellar projections terminate primarily in lobules II (mean 27.14%), III (mean 38.68%), and IV (mean 19.31%). Different-sized bilateral injections restricted to L1 were used to study the organization of intrasegmental spinocerebellar projections. Small injections into L1 labeled a limited number of terminals which were located either in clusters or were spatially isolated. Intermediate-sized intrasegmental injections resulted in additional clusters of labeled terminals. Many of the terminal clusters were spatially related and formed larger irregularly shaped patches. Large intrasegmental injections labeled terminal clusters and patches that were discontinuous but aligned parallel to the longitudinal (transverse) axis of lobules II-IV. Injections including segments rostral and caudal to L1 were used to study the topography of intersegmental lower thoracic-upper lumbar spinocerebellar projections. Multisegmental injections increased the number of labeled terminal clusters and patches which obscured the pattern of segmental input, but there was still a transversely oriented pattern of termination. Distinct transversely aligned terminal free areas remained apparent. Lower thoracic-upper lumbar spinocerebellar projections terminated in both the outer- and inner-halves of the granule cell layer, but overall were more numerous in the outer-half of this layer. In serially spaced sagittal sections, however, the majority of terminals alternated between the outer- and inner-halves of the granule cell layer. Outer- and inner-terminals were not spatially segregated in their orthogonal distribution. These results indicate lower thoracic-upper lumbar spinocerebellar projections have a complex three-dimensional topography in the anterior lobe. These findings are discussed in relation to previous findings for a sagittally oriented topography for lower thoracic-upper lumbar spinocerebellar projections and in the context of how cerebellar somatosensory afferent input may be organized.
在成年大鼠中，对下胸段-上腰段（T12-L3）脊髓投射至小脑前叶的麦胚凝集素-辣根过氧化物酶/辣根过氧化物酶标记的苔藓纤维终末的局部解剖结构进行了定量分析。基于计算机的图像分析在未展开的前叶皮质的二维重建中描绘了标记终末的正交（平行于表面）分布。通过计算终末是否位于颗粒细胞层的外半层或内半层来描绘颗粒细胞层内终末的径向（垂直于表面）分布。计算每个小叶中标记终末的数量。在前叶中，下胸段-上腰段脊髓小脑投射主要终止于小叶II（平均27.14%）、III（平均38.68%）和IV（平均19.31%）。使用局限于L1的不同大小的双侧注射来研究节段内脊髓小脑投射的组织。向L1进行小剂量注射标记了数量有限的终末，这些终末要么成簇分布，要么在空间上孤立。中等大小的节段内注射导致额外的标记终末簇。许多终末簇在空间上相关并形成更大形状不规则且不连续的斑块。大剂量节段内注射标记了终末簇和斑块，这些终末簇和斑块是不连续的，但与小叶II-IV的纵向（横向）轴平行排列。包括L1头侧和尾侧节段的注射用于研究节段间下胸段-上腰段脊髓小脑投射的局部解剖结构。多节段注射增加了标记终末簇和斑块的数量，这掩盖了节段性输入的模式，但仍然存在横向排列的终止模式。明显的横向排列的终末自由区仍然可见。下胸段-上腰段脊髓小脑投射终止于颗粒细胞层的外半层和内半层，但总体上在该层的外半层数量更多。然而，在连续间隔的矢状切片中，大多数终末在颗粒细胞层的外半层和内半层之间交替。外终末和内终末在其正交分布中在空间上没有分离。这些结果表明，下胸段-上腰段脊髓小脑投射在前叶具有复杂的三维局部解剖结构。结合先前关于下胸段-上腰段脊髓小脑投射矢状位局部解剖结构的研究结果以及小脑躯体感觉传入输入可能的组织方式，对这些发现进行了讨论。
