Matsushita M, Xiong G
Department of Anatomy, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
J Comp Neurol. 2001 Mar 26;432(1):101-18. doi: 10.1002/cne.1091.
In the upper cervical spinal segments, neurons in the medial part of lamina VI give rise to uncrossed spinocerebellar axons, whereas the central cervical nucleus (CCN) and neurons in laminae VII and VIII give rise to crossed spinocerebellar axons. Using anterograde labeling with biotinylated dextran in the rat, we examined the projections of these neuronal groups to the cerebellar nuclei. Uncrossed and crossed projections were distinguished by cerebellar lesions placed on the side contralateral or ipsilateral to the tracer injections confined to the second and third cervical spinal segments (C2 and C3, respectively). Labeled terminals of uncrossed projections were seen in the middle, dorsal, and ventrolateral parts of the middle subdivision and in the ventral part of the caudomedial subdivision of the medial nucleus. In the anterior interpositus nucleus, terminals were seen in the middle of the mediolateral extent, whereas, in the posterior interpositus nucleus, they were seen in lateral and caudal parts. The terminals of crossed projections from the CCN were distributed ventrally in medial to ventrolateral parts of the middle subdivision of the medial nucleus. Some terminals were seen in the caudomedial subdivision of the medial nucleus. In the anterior interpositus nucleus, labeled terminals were seen mainly in rostromedial parts, whereas, in the posterior interpositus nucleus, they were seen in caudal and dorsal parts of the medial half. The present study suggests that the medial lamina VI group and the CCN in the upper cervical segments project to the different areas of the cerebellar nuclei and are concerned with different functions.
在上颈髓节段，VI层内侧的神经元发出不交叉的脊髓小脑轴突，而颈中央核（CCN）以及VII层和VIII层的神经元发出交叉的脊髓小脑轴突。我们利用生物素化葡聚糖在大鼠体内进行顺行标记，研究了这些神经元群向小脑核的投射。通过在分别局限于第二和第三颈髓节段（C2和C3）的示踪剂注射对侧或同侧放置小脑损伤来区分不交叉和交叉投射。不交叉投射的标记终末见于内侧核中间亚核的中部、背侧和腹外侧部分以及尾内侧亚核的腹侧部分。在前间位核中，终末见于中外侧范围的中部，而在后间位核中，它们见于外侧和尾侧部分。来自CCN的交叉投射终末分布在内侧核中间亚核内侧至腹外侧部分的腹侧。在内侧核的尾内侧亚核中也可见到一些终末。在前间位核中，标记终末主要见于嘴内侧部分，而在后间位核中，它们见于内侧半的尾侧和背侧部分。本研究表明，上颈段的内侧VI层神经元群和CCN投射到小脑核的不同区域，并与不同功能相关。
