Haines D E, Dietrichs E
Department of Anatomy, University of Mississippi Medical Center, Jackson 39216.
Anat Embryol (Berl). 1991;184(3):255-68. doi: 10.1007/BF01673260.
The distribution of corticonuclear fibers to medial-most parts of the posterior interposed nucleus (NIP) from lateral areas of the vermis was studied in the squirrel monkey (Saimiri sciureus), using a silver impregnation method. The origin and course of degenerated fibers were studied in serial sections. The distribution pattern of corticonuclear fibers from a series of small well localized lesions placed in the vermis and paravermal cortex of lobule V is compatible with the interpretation that an x zone is present in Saimiri. A comparison of the positions of lesions and the trajectory of fibers arising therein suggests that corticonuclear input to medial-most parts of the NIP originated from a narrow cortical area (about 0.5-0.7 mm wide) located between a cortical area projecting into the medial cerebellar nucleus (the A zone) and a laterally adjacent area (the B zone) which related to the lateral vestibular nucleus. This NIP-projecting cortical area, located about 1.7 mm to 2.5 mm off the midline in lobule V, is interpreted as the x zone in this primate; it extends from lobule IV into lobule VI in squirrel monkey. Corticonuclear fibers of zone x in this primate form a comparatively small terminal field in the medial-most portions of NIP. This contrasts with the distribution of corticonuclear fibers of the C2 zone which consistently distribute to terminal fields that are shifted into more central areas of NIP. There appears to be no overlap of the corticonuclear terminal fields in the NIP for zone x versus the C2 zone. These results were correlated with data from the literature on the distribution of olivocerebellar fibers to the x zone and the C2 zone and the arrangement of cerebellar nucleoolivary projections into the inferior olive from the NIP. The x zone and the C2 zone both receive input from the contralateral medial accessory olive (MAO), both zones project into the NIP, and the NIP projects into those regions of the MAO which, in turn, project to these respective cortical zones and into the NIP. This suggest that the x zone is a component of the NIP-MAO circuit. Furthermore the proposed function of the x zone would support the view that this sagittal strip may have a more extensive rostrocaudal distribution in primates as compared to the cat.
采用银浸染法，在松鼠猴（Saimiri sciureus）中研究了来自蚓部外侧区域的皮质核纤维向最内侧的后间位核（NIP）的分布。在连续切片中研究了变性纤维的起源和走行。在小叶V的蚓部和旁蚓皮质中放置一系列小的、定位良好的损伤，来自这些损伤区域的皮质核纤维的分布模式符合这样的解释，即松鼠猴中存在一个x区。损伤位置与从中发出的纤维轨迹的比较表明，向NIP最内侧部分的皮质核输入起源于一个狭窄的皮质区域（约0.5 - 0.7毫米宽），该区域位于投射到内侧小脑核的皮质区域（A区）和与外侧前庭核相关的外侧相邻区域（B区）之间。这个投射到NIP的皮质区域位于小叶V中距中线约1.7毫米至2.5毫米处，在这种灵长类动物中被解释为x区；在松鼠猴中，它从小叶IV延伸到小叶VI。这种灵长类动物中x区的皮质核纤维在NIP的最内侧部分形成相对较小的终末场。这与C2区的皮质核纤维分布形成对比，C2区的皮质核纤维始终分布到向NIP更中央区域偏移的终末场。在NIP中，x区与C2区的皮质核终末场似乎没有重叠。这些结果与文献中关于橄榄小脑纤维向x区和C2区的分布以及从小脑核橄榄投射从NIP进入下橄榄核的排列的数据相关。x区和C2区都接受来自对侧内侧副橄榄核（MAO）的输入，两个区都投射到NIP，并且NIP投射到MAO的那些区域，而这些区域又投射到这些各自的皮质区并进入NIP。这表明x区是NIP - MAO回路的一个组成部分。此外，所提出的x区的功能支持这样一种观点，即与猫相比，这个矢状带在灵长类动物中可能具有更广泛的前后分布。
