Hrycyshyn A W, Flumerfelt B A
J Comp Neurol. 1981 Apr 10;197(3):503-16. doi: 10.1002/cne.901970310.
The mode and pattern of termination of the afferents to the lateral reticular nucleus (LRN) of the cat were examined at the cellular level through the ultrastructural localization of induced degeneration. Examination of the LRN following hemicordotomy at the fifth and sixth cervical levels revealed that most of the degenerating terminals were in contact with intermediate and distal dendrites, and that most of these degenerating terminals were small and contained round vesicles. Fewer degenerating terminals were observed on the somata and proximal dendrites after spinal hemisection, and most of these terminals were large and contained round vesicles. Following lesions of the pericruciate cortex, small degenerating terminals were occasionally observed making contact onto intermediate and distal dendrites. Degenerating rubral terminals were observed synapsing on somata, somatic and dendritic spines, proximal dendrites and most commonly on intermediate and distal dendrites following lesioning of the red nucleus. The degenerating axosomatic rubro-LRN terminals belonged to the large, round-vesicle terminal population, while those degenerating terminals contacting intermediate and distal dendrites belonged to the small, round-vesicle population. Small, degenerating terminals were occasionally seen following lesions of the fastigial nucleus, and they made synaptic contact mainly onto intermediate and distal dendrites and dendritic spines. The present ultrastructural observations taken together with the convergence pattern of LRN afferents and the available electrophysiological data on inputs to the LRN suggest an extensive integration of converging impulses from two or more afferent sources to the rostral LRN neurons. The results of this study therefore support the veiw that the rostral LRN functions as a comparator of command signals from the motor cortex and red nucleus and feedback signals from the spinal cord and cerebellum during ongoing movement.
通过诱导变性的超微结构定位，在细胞水平上研究了猫外侧网状核（LRN）传入纤维的终止方式和模式。在第五和第六颈椎水平进行脊髓半横切术后对LRN的检查显示，大多数变性终末与中间和远端树突接触，并且这些变性终末大多数较小且含有圆形囊泡。脊髓半切术后，在胞体和近端树突上观察到的变性终末较少，并且这些终末大多数较大且含有圆形囊泡。在十字周皮质损伤后，偶尔会观察到小的变性终末与中间和远端树突接触。在红核损伤后，观察到变性的红核终末与胞体、胞体和树突棘、近端树突形成突触，最常见的是与中间和远端树突形成突触。变性的轴-体红核-LRN终末属于大的、圆形囊泡终末群体，而那些与中间和远端树突接触的变性终末属于小的、圆形囊泡群体。在顶核损伤后偶尔会看到小的变性终末，它们主要与中间和远端树突以及树突棘形成突触接触。目前的超微结构观察结果，连同LRN传入纤维的汇聚模式以及关于LRN输入的现有电生理数据，表明来自两个或更多传入源的汇聚冲动广泛整合到延髓LRN神经元。因此，本研究结果支持这样一种观点，即在进行性运动期间，延髓LRN作为运动皮层和红核的指令信号与脊髓和小脑的反馈信号的比较器发挥作用。
