Tsukahara N, Bando T, Murakami F, Oda Y
Brain Res. 1983 Sep 12;274(2):249-59. doi: 10.1016/0006-8993(83)90702-3.
Intracellular recordings were made from neurons of the red nucleus (RN) in cats where the cerebellar cortical effects were removed by chronic ablation of the intermediate part of the anterior lobe of the cerebellum. A prolonged depolarization could be elicited by stimulating the nucleus interpositus (IP) of the cerebellum, nucleus reticularis tegmenti pontis (NRTP) and the nucleus reticularis paramedianus (PMRN). This prolonged depolarization was abolished after cooling the inferior and middle cerebellar peduncles and persisted after ablation of the cerebral sensorimotor cortex. The prolonged depolarization was also recorded intracellularly from IP neurons. It was concluded that the prolonged depolarization set up in RN neurons is due to the repetitive discharges of IP neurons which produces tonic bombardment onto RN cells. The mechanisms of the repetitive discharges of IP neurons are considered to be due to impulse reverberation via the IP. The dynamic properties of the reverberating circuits were characterized by regenerative behavior. Above and below threshold, there were two states, the excited state where many constituent neurons were active, and the resting state where all neurons were inactive. It was found that cats with chronically stimulated cerebral peduncle (CP), and tested in an acute experiment, showed sometimes effective for inducing the prolonged depolarization and repetitive discharges of RN neurons by stimulation of IP. The prolonged depolarization thus produced could be reversibly abolished by cooling the middle and inferior cerebellar peduncles. The possible constituent neurons of the reverberating circuits were investigated in light of previous physiological investigations of stimulating the NRTP, PMRN, nucleus reticularis lateralis (LRN), nucleus olivaris inferior (IO) and recording EPSPs in RN cells. The RN cells receive axon reflex activation from NRTP and PMRN, and disynaptic excitation from NRTP, PMRN, LRN and IO. Based on these and other available data, the components of the cerebello-precerebellar reverberating circuits are discussed.
在猫身上，通过慢性切除小脑前叶中间部分来消除小脑皮质效应后，从红核（RN）神经元进行细胞内记录。刺激小脑间位核（IP）、脑桥被盖网状核（NRTP）和正中旁网状核（PMRN）可诱发长时间去极化。冷却小脑下脚和中脚后，这种长时间去极化消失，而在切除大脑感觉运动皮层后仍持续存在。在IP神经元中也细胞内记录到了长时间去极化。得出的结论是，RN神经元中产生的长时间去极化是由于IP神经元的重复放电，对RN细胞产生了强直性轰击。IP神经元重复放电的机制被认为是由于通过IP的冲动折返。折返回路的动态特性以再生行为为特征。在阈值上下有两种状态，一种是许多组成神经元活跃的兴奋状态，另一种是所有神经元都不活跃的静息状态。发现慢性刺激脑桥（CP）并在急性实验中进行测试的猫，有时通过刺激IP能有效诱导RN神经元的长时间去极化和重复放电。这样产生的长时间去极化可通过冷却小脑中和下脚而可逆地消除。根据先前对刺激NRTP、PMRN、外侧网状核（LRN）、下橄榄核（IO）以及记录RN细胞中兴奋性突触后电位（EPSP）的生理学研究，对折返回路可能的组成神经元进行了研究。RN细胞接受来自NRTP和PMRN的轴突反射激活，以及来自NRTP、PMRN、LRN和IO的双突触兴奋。基于这些及其他现有数据，讨论了小脑 - 前小脑折返回路的组成部分。
