OLIGOSYNAPTIC EXCITATION OF MOTO-NEURONS BY IMPULSES IN GROUP IA MUSCLE-SPINDLE AFFERENTS IN THE CAT
OLIGOSYNAPTIC EXCITATION OF MOTO-NEURONS BY IMPULSES IN GROUP IA MUSCLE-SPINDLE AFFERENTS IN THE CAT
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DOI：
10.1113/jphysiol.1981.sp013797
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发表时间：
1981-01-01
影响因子：
5.5
通讯作者：
MACKEL, R
中科院分区：
文献类型：
--
作者：
JANKOWSKA, E;MCCREA, D;MACKEL, R
从后肢运动神经元的细胞内记录被用来调查是否双和三突触（寡突触）兴奋性突触后电位（EPSP）引起的Ia组肌梭传入在这些运动神经元中，这样的电位引起Ib腱器官传入或整个组I传入。小腿三头肌和跖肌的Ia传入被激活，或者选择性地通过这些肌肉的单个短暂伸展，或者通过施加到神经的电刺激与Ib传入一起。低于Ib传入阈值（10-35 μ m）的肌肉拉伸诱发EPSP，其出现在与传入和运动神经元之间的双突触和三突触耦合相容的lavonium。大多数这些EPSP的潜伏期太短，让他们的调解组II传入，如果任何被激活的应用拉伸。它们也太短，与背根反射的效果不相容。这些EPSP归因于Ia传入的寡突触作用。牵张诱发的双突触和三突触Ia型EPSP在83%的运动神经元中被发现，其中EPSP由激活Ia和Ib传入的刺激诱发;在5种运动神经元中，它们被发现的比例> 90%。Ia组肌梭传入明显引起不仅抑制，但也兴奋的行动与Ib组腱器官传入平行。Ia寡突触牵张诱发的兴奋从踝关节和脚趾伸肌的分布进行了比较，如前所述的Ia非互惠抑制的分布。兴奋占主导地位的后二头肌半腱肌运动神经元和抑制在其他物种的运动神经元的调查，除了内在的脚肌肉（胫骨运动神经元）;后者的比例相似，表现出兴奋和抑制。在某些运动神经元物种中，特别是在个体运动神经元中，Ia起源的寡突触EPSP和抑制性突触后电位（IPSP）的发生表明I组avverents和这些运动神经元之间存在许多反射通路。在更强的刺激之后，由近阈值电刺激诱发的一些EPSP的消失表明介导I组动作的中间神经元的各种功能组之间的相互作用。
Intracellular recording from hind-limb motoneurons was used to investigate whether di- and trisynaptic (oligosynaptic) excitatory post-synaptic potentials (EPSP) are evoked from group Ia muscle spindle afferents in those motoneurons in which such potentials are evoked from Ib tendon organ afferents or entire group I afferents. Ia afferents of triceps surae and plantaris were activated either selectively by single brief stretches of these muscles, or together with Ib afferents by electrical stimuli applied to the nerves. Muscle stretches below threshold for Ib afferents (10-35 .mu.m) evoked EPSP which appeared with latencies compatible with di- and trisynaptic coupling between the afferents and the motoneurons. The latencies of a majority of these EPSP were too short to allow their mediation by group II afferents, if any were activated by the applied stretches. They were also too short to be compatible with effects attributable to dorsal root reflexes. These EPSP are attributed to oligosynaptic actions of Ia afferents. Stretch-evoked di- and trisynaptic Ia EPSP were found in 83% of motoneurons in which EPSP were evoked by stimuli which activated both Ia and Ib afferents; in 5 motoneuron species they were found in > 90%. Group Ia muscle spindle afferents apparently evoke not only inhibitory but also excitatory actions in parallel with group Ib tendon organ afferents. The distribution of Ia oligosynaptic stretch-evoked excitation from ankle and toe extensor muscles was compared with the distribution of Ia non-reciprocal inhibition as previously described. Excitation predominated in posterior biceps-semitendinosus motoneurons and inhibition in other species of motoneurons investigated, except those of intrinsic foot muscles (tibial motoneurons); similar proportions of the latter showed excitation and inhibition. Occurrence of oligosynaptic EPSP and inhibitory post-synaptic potentials (IPSP) of Ia origin in some motoneuron species and in particular in individual motoneurons is indicative of a number of reflex pathways between group I avverents and these motoneurons. The disappearance of some of the EPSP evoked by near-threshold electrical stimulation following stronger stimuli indicates interactions between various functional groups of interneurons mediating group I actions.