Parllel and multiple integration mechanisms of motor segments related to the control of posture and locomotion by the newly identified cerebellar locomotor region

本研究以完整的成年猫和幼年日本猴(M.fuscata)为研究对象。在猫的小脑运动区(CLR)植入刺激微电极，该区域在解剖上与Russel钩束中线相对应，多条升、下行迷走神经纤维通过该区域交叉。在一只无拘无束、清醒的猫身上，列车脉冲CLR微刺激(200赫兹)诱发出前后肢协调良好的四足(Q)运动。在CLR部位造成微小损伤后，猫仍然可以自发行走，但前后肢运动的协调性受到相当大的损害。我们认为，CLR刺激导致双侧下行至脑干的多个迷走神经纤维被激活，从而同时兴奋主要下行运动通路的起源细胞，并且CLR损伤阻断了源自顶核(FN)的运动驱动信号向运动相关的脑干-脊髓机制的传递。在一只四足或两足行走的猴子身上，我们通过正电子发射计算机断层扫描(PET)确定了活跃的大脑区域。在Q和两足(B)运动任务的执行过程中，我们发现小脑、视觉和运动皮质多个不同脑区的神经元活动增强。结果表明，B运动时视觉运动协调的功能意义比Q运动时强，而Q运动时小脑起主要作用。基于这些结果，我们提出了一个新的工作假设，即FN是参与猫和猴0和B运动的启动和控制的脊髓上中枢之一，与其一起，S唯一的多条和平行的输出通路。

Intact adult cats and juvenile Japanese monkeys (M. fuscata) were the subject of this study. In cats, a stimulating microelectrode was implanted targeting cerebellar locomotor region (CLR), which corresponds anatomically to the midline of hook bundle of Russel, through which multiple ascending and descending fastigiofugal fibers decussate. In an unrestrained, awake cat, a train pulse CLR microstimulation (200 Hz) evoked fore- and hindlimb well coordinated quadrupedal (Q) locomotion. After making a microlesion at the CLR site, the cat could still walk spontaneously but with considerably impaired coordination of fore- and hindlimb movements. We consider that CLR stimulation resulted in an activation of multiple fastigiofugal fibers descending bilaterally to the brainstem, thus simultaneously exciting cells of origin of major descending motor pathways, and that CLR lesion interrupted transmission of locomotor driving signals originating from the fastigial nucleus (FN) to locomotor-related brainstem-spinal cord mechanisms. In a single monkey walking either quadrupedally or bipedally, we have identified active brain regions by PET. During execution of Q and bipedal (B) locomotion task, we found that neuronal activities at multiple but different brain regions of the cerebellum, visual and motor cortices were enhanced. The results demonstrated that functional significance of visuomotor coordination is stronger during execution of B locomotion than that during execution of Q locomotion, and that in the latter, the cerebellum plays a major role. Based on the results obtained, we propose a new working hypotheis that the FN, with it s unique multiple and parallel output pathways, is one of the supraspinal centers involved in the initiation and control of 0 and B locomotion in both cat and monkey.