POSITIVE FEEDBACK LOOPS FROM PROPRIOCEPTORS INVOLVED IN LEG MOVEMENTS OF THE LOCUST
POSITIVE FEEDBACK LOOPS FROM PROPRIOCEPTORS INVOLVED IN LEG MOVEMENTS OF THE LOCUST
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DOI：
10.1007/bf00604897
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发表时间：
1988-01-01
影响因子：
2.1
通讯作者：
PFLUGER, HJ
中科院分区：
文献类型：
--
作者：
BURROWS, M;PFLUGER, HJ
两个companiform感器（CS）上的近端胫骨的后腿监测应变设置时，蝗虫准备踢，或当遇到阻力在运动过程中。这些传入神经与中间神经元和腿部运动神经元的连接已经被研究，并与它们在运动中的作用相关。当屈肌和伸肌胫束共同收缩时，在踢腿前，来自两个钟状感器的传入以高达650 Hz的频率尖峰。当胫骨主动或被动伸展时，除非遇到阻力，否则它们不会出现尖峰。然后，快速伸肌胫前肌运动神经元（FETi）在具有来自CS传入纤维的反馈的推力反应中产生一系列尖峰以维持兴奋。破坏这两个钟状感器就取消了FETi的再激发。单一感器的机械刺激可使伸肌和屈肌胫前肌运动神经元兴奋。来自任一CS的单一传入在快伸肌运动神经元和某些快屈肌胫前肌运动神经元中引起EPSP，这些神经元跟随每个感觉尖峰，中枢潜伏期为1.6 ms，表明直接连接。来自一个受体的输入足够强大以引起FETi中的尖峰。缓慢的伸肌运动神经元不接受直接输入，尽管它是兴奋的，而缓慢的屈肌运动神经元不受影响。一些非尖峰中间神经元与运动神经元平行地接受来自两个传入神经的直接连接。其中一个中间神经元可能通过去抑制来兴奋缓慢和快速的胫骨伸肌运动神经元。这个interneurone的超极化取消了CS的兴奋作用，对缓慢的伸肌运动神经元，并减少了快速的兴奋。去抑制通路可能涉及第二个非尖峰神经元与两个伸肌运动神经元的直接抑制连接。其他非尖峰神经元将CS传入神经的作用分配给其他关节的运动神经元。钟状感器的传入分支和运动神经元和中间神经元的传入分支投射到后胸神经节的相同区域。所描述的路径将确保当胫骨克服阻力伸展时，伸肌产生更多的力。对伸肌和屈肌运动神经元的兴奋性反馈也将有助于它们在产生踢腿所需的力时的共同收缩。
Two companiform sensilla (CS) on the proximal tibia of a hindleg monitor strains set up when a locust prepares to kick, or when a resistance is met during locomotion. The connections made by these afferents with interneurones and leg motor neurones have been ivestigated and correlated with their role in locomotion. When flexor and extensor tibiae muscle cocontract before a kick afferents from both campaniform sensilla spike at frequencies up to 650 Hz. They do not spike when the tibia is extended actively or passively unless it encounters a resistance. The fast extensor tibiae motor neurone (FETi) then produces a sequence of spikes in a thrusting response with feedback from the CS afferents maintaining the excitation. Destroying the two campaniform sensilla abolishes the re-excitation of FETi. Mechanical stimulation of a single sensillum excites extensor and flexor tibiae motor neurones. The single afferent from either CS evokes EPSPs in the fast extensor motor neurone and in certain fast flexor tibiae motor neurones which follow each sensory spike with a central latency of 1.6 ms that suggest direct connections. The input from one receptor is powerful enough to evoke spikes in FETi. The slow extensor motor neurone does not receive a direct input, although it is excited and slow flexor tibiae motor neurones are unaffected. Some nonspiking interneurones receive direct connections from both afferents in parallel with the motor neurones. One of these interneurones excites the slow and fast extensor tibiae motor neurones probably by disinhibition. Hyperpolarization of this interneurone abolishes the excitatory effect of the CS on the slow extensor motor neurone and reduces the excitation of the fast. The disinhibitory pathway may involve a second nonspiking interneurone with direct inhibitory connections to both extensor motor neurones. Other nonspiking interneurones distribute the effects of the CS afferents to motor neurones of other joints. The branches of the afferents from the campaniform sensilla and those of the motor neurones and interneurones in which they evoke EPSPs project to the same regions of neuropil in the metathoracic ganglion. THe pathway described will ensure that more force is generated by the extensor muscle when the tibia is extended against a resistance. The excitatory feedback to the extensor and flexor motor neurones will also contribute to their co-contraction when generating the force necessary for a kick.