Cerebellar Influence on Olivary Excitability in the Cat
Cerebellar Influence on Olivary Excitability in the Cat
复制标题
小脑对猫橄榄兴奋性的影响
DOI：
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发表时间：
1995
影响因子：
3.4
通讯作者：
J. Voogd
中科院分区：
文献类型：
--
作者：
T. Ruigrok;J. Voogd
本研究探讨小脑对猫下橄榄核神经元兴奋性的影响。通过电生理和解剖学技术研究了从小脑核到下橄榄核的两条主要通路。第一条是兴奋性通路，通过中脑间脑交界处的核团与下橄榄核连接小脑核团。第二种是直接的GABA能核橄榄途径。在内侧副橄榄和主橄榄的吻侧部分获得的细胞内和细胞外记录显示，在间脑连接处传递的三个脉冲的短脉冲串的电刺激导致大多数橄榄神经元的短潜伏期激活（4-8 ms）。除了短潜伏期激活外，超过一半的装置显示出一致的反应，潜伏期更长（约180 ms）。许多对间脑刺激有反应的单位（66%）也可以被具有类似刺激范例（潜伏期9-15 ms）的上级小脑脚刺激激活。然而，在这种情况下，一致的长潜伏期反应很少记录（7%）。为了区分这两条通路的作用，这两条通路都是由上级小脑脚刺激激活的，在六个实验中，在脑干中对核橄榄纤维进行电解损伤。在实验结束时，通过从吻侧下橄榄逆行辣根过氧化物酶追踪，在三例病例中验证了这种病变的效果。这一次只进行了细胞外记录。刺激间脑交界处仍然导致容易激活的橄榄体单位，这表明激发长潜伏期动作电位的可能性增加。刺激上级小脑脚，导致短潜伏期范围内激活橄榄核单位的概率降低50%。然而，观察到在长潜伏期内触发动作电位的机会增加了5倍，这意味着许多单位仅对长潜伏期动作电位作出反应。用我们的实验范式获得的结果似乎是神秘的，因为已经确定核橄榄途径是GABA能的，因此，按照惯例，应该对橄榄神经元具有抑制作用。然而，这是可能的解释这些结果的橄榄神经元的动态耦合。这一概念归因于核橄榄通路在调节橄榄神经元之间的电子耦合程度（可能通过分流机制）中的重要作用，因此可能是调节同步和节律性橄榄放电的重要工具。因此，预期该途径的损伤将导致大的橄榄细胞聚集体的偶联。似乎这些强耦合的细胞群更难被传入的齐射激活。然而，一旦激活，耦合的橄榄神经元开发的膜电位的振荡，可以传送，电子，到邻近的神经元，随后，在去极化阶段的振荡，导致更容易触发反弹或longlatency响应。它的结论是，小脑输出可能不仅抑制橄榄神经元，但也与兴奋性的核-中脑-橄榄回路，调制橄榄的兴奋性在一个相当复杂的方式。
This study examines the influence of the cerebellum on the excitability of inferior olivary neurons in the cat. Two major pathways from the cerebellar nuclei to the inferior olive have been investigated by electrophysiological and anatomical techniques. The first, excitatory pathway connects the cerebellar nuclei through nuclei at the mesodiencephalic junction with the inferior olive. The second is the direct, GABAergic, nucleo‐olivary pathway. Intra‐ as well as extracellular recordings obtained in the rostral part of the medial accessory and principal olives revealed that electrical stimulation with a short burst of three pulses delivered at the mesodiencephalic junction results in short‐latency activation (4–8 ms) of most olivary neurons. More than half of the units showed, in addition to the short‐latency activation, a consistent response with a much longer latency (‐180 ms). Many units (66%) that responded to mesodiencephalic stimulation could also be activated by superior cerebellar peduncle stimulation with a similar stimulation paradigm (latency 9–15 ms). However, in such cases consistent long latency responses were only rarely recorded (7%). To distinguish between the effect of the two pathways, both of which are activated by superior cerebellar peduncle stimulation, an electrolytic lesion of the nucleo‐olivary fibres was made in the brainstem in six experiments. The effect of this lesion was verified in three cases by retrograde horseradish peroxidase tracing from the rostral inferior olive at the end of the experiment. This time only extracellular recordings were made. Stimulation of the mesodiencephalic junction still resulted in easily activated olivary units which showed an increased probability of firing a long‐latency action potential. Stimulation of the superior cerebellar peduncle now resulted in a 50% decrease in probability of activating olivary units in the short‐latency range. However, a five‐fold increase in the chance of triggering action potentials in the long latency interval was noted, implying that many units reacted only with a long‐latency action potential. The results obtained with our experimental paradigm appear enigmatic since it is well established that the nucleo‐olivary pathway is GABAergic and thus, by convention, should be inhibitory to the olivary neurons. However, it is possible to explain these results in terms of dynamic coupling of olivary neurons. This concept ascribes an important role to the nucleo‐olivary pathway in regulating the degree of electronic coupling between olivary neurons (probably by a shunting mechanism) and as such may be an important instrument in the regulation of synchronous and rhythmic olivary discharges. Thus, lesion of this pathway would be expected to result in coupling of large aggregates of olivary cells. It seems likely that these strongly coupled cell ensembles are more difficult to activate by incoming afferent volleys. However, once activated, the coupled olivary neurons develop an oscillation of the membrane potential which may be conveyed, electronically, to neighbouring neurons and subsequently, during the depolarizing phase of the oscillation, result in a more easily triggered rebound or longlatency response. It is concluded that cerebellar output may not merely inhibit olivary neurons, but also, in conjunction with an excitatory nucleo‐mesodiencephalo‐olivary circuit, modulate olivary excitability in a rather complex manner.
抑制红核刺激产生的猫下橄榄神经元的感觉反应。
影响因子：
2.5
作者：
Weiss,C;Houk,JC;Gibson,AR
通讯作者：
Gibson,AR