Reflex Control of Abdominal Flexor Muscles in the Crayfish
Reflex Control of Abdominal Flexor Muscles in the Crayfish
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小龙虾腹部屈肌的反射控制
DOI：
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发表时间：
1965
期刊：
影响因子：
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通讯作者：
K. Takeda
中科院分区：
文献类型：
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作者：
D. Kennedy;K. Takeda
1.小龙虾腹部的屈肌分为两个系统：一组紧张性浅表肌肉，以及一系列复杂的巨大屈肌，它们产生强大的抽搐，但从不表现出紧张性收缩。肌肉类型在组织学上是有区别的，并且也分别受神经支配：主要的屈肌接受十个大的运动轴突，而缓慢的浅表肌肉接受六个较小的运动轴突。2.研究的主要屈肌纤维几乎都是三重神经支配的;每个都接受来自（a）“运动巨”轴突，（B）几个特定的非巨运动轴突之一，和（c）一个共同的抑制剂的终末。3.由于运动巨轴突和非巨轴突引起的兴奋性连接电位（e. j. p. s）相似且较大;每种都可能触发次级、主动“尖峰”，因此通常产生100 mV的连接后反应。个或多个.不同的反应是，运动巨e. j. p.显示了一个戏剧性的减少后，重复刺激，而由于非巨大的运动轴突表现出一些促进。4.中央巨纤维的活动驱动两个运动轴突。当运动巨肌系统完全休息时，对两者的反应略大于单独对两者的反应;当通过刺激中央巨肌纤维激活时，由于中枢反射时间的差异，交界电位被异步诱发，有时会导致肌纤维中的双尖峰。在重复刺激时，对巨人的反应降低到非常低的水平;这伴随着连续反射诱发的抽搐中产生的张力的降低。因此，巨大的运动系统显然起到了为逃生过程中一系列游泳动作中的前几个“翻转”提供额外张力的作用。5.在抑制剂轴突的冲动，即使在最佳的时间间隔，减少兴奋性连接后电位的振幅只有少量的，其效果在缩短持续时间是更显着的。据推测，外周抑制剂的功能是缩短兴奋性去极化，从而终止可能反对随后的反射行动的持续紧张。
1. The flexor musculature of the crayfish abdomen is divided into two systems: a set of tonic superficial muscles, and a complex series of massive flexor muscles that produce powerful twitches but never exhibit tonic contractions. The muscle types are histologically differentiated, and also separately innervated: the main flexors receive ten large motor axons, and the slow superficial muscles six smaller ones. 2. Fibres of the main flexor muscles studied are almost all triply innervated; each receives endings from ( a ) the ‘motor giant’ axon, ( b ) one of several specific non-giant motor axons, and ( c ) a common inhibitor. 3. Excitatory junctional potentials (e.j.p.s) due to motor giant and non-giant axons are similar and large; each may trigger secondary, active ‘spikes’, thus often producing post-junctional responses of 100 mV. or more. The responses differ in that the motor giant e.j.p. shows a dramatic decrease upon repetitive stimulation, whereas that due to non-giant motor axons exhibits some facilitation. 4. Activity in the central giant fibres drives both motor axons. The response to both, when the motor giant system is fully rested, is slightly larger than that to either alone; when activated by stimulation of the central giant fibre the junctional potentials are evoked asynchronously due to differences in central reflex time, and double spiking in the muscle fibres sometimes results. Upon repeated stimulation the response to the giant is reduced to a very low level; this is accompanied by a decrease in the tension developed in successive reflexly evoked twitches. The motor giant system thus apparently functions to provide additional tension for the first few ‘flips’ in a series of swimming movements during escape. 5. Impulses in the inhibitor axon, even at the optimal interval, reduce the amplitude of excitatory post-junctional potentials by only a small amount; their effect in shortening duration is more notable. It is postulated that the peripheral inhibitor functions to cut short excitatory depolarizations and hence to terminate lingering tension that might oppose subsequent reflex actions.