EVIDENCE FOR NON-MONOSYNAPTIC-IA EXCITATION OF HUMAN WRIST FLEXOR MOTONEURONES, POSSIBLY VIA PROPRIOSPINAL NEURONS
EVIDENCE FOR NON-MONOSYNAPTIC-IA EXCITATION OF HUMAN WRIST FLEXOR MOTONEURONES, POSSIBLY VIA PROPRIOSPINAL NEURONS
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DOI：
10.1113/jphysiol.1988.sp017359
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发表时间：
1988-11-01
影响因子：
5.5
通讯作者：
PIERROTDESEILLIGNY, E
中科院分区：
文献类型：
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作者：
MALMGREN, K;PIERROTDESEILLIGNY, E
1.研究了激活人正中神经和尺神经的低阈值传入引起腕屈肌运动神经元的神经元间兴奋的可能性。使用了两种独立的技术：(1)间接的腕屈肌H反射的时空易化技术：(2)用刺激后时间直方图(PSTH)法测量不同刺激后自发激活的运动单位的放电概率。2.弱电刺激(正中神经、尺神经、皮肤和皮神经分支)和轻敲腕屈肌腱可诱发条件性抽射。3.在H反射实验中，比较了两种条件刺激单独作用和联合作用的效果。在某些实验条件下，当两个条件刺激组合时，诱发的反射的易化性大于单独刺激效应的代数和。这种额外易化的中枢潜伏期为3ms，被称为“额外易化”。有人认为，额外的促进作用反映了运动神经元前水平的总和。4.计算刺激正中神经或尺神经后自发激活的腕屈肌和尺侧腕屈肌运动单位的PSTH。在60%的记录中，传入抽射引起放电概率增加的峰值，其潜伏期比单突触Ia潜伏期长3-6ms。5.PSTH中反射的额外易化和波峰后移均由极低阈值传入引起。在反射实验中证实了Ia传入的贡献。第一类传入物质单独负责非单突触兴奋的开始，但可能是皮肤传入物质提供了较晚的贡献。6.根据两种方法研究的非单突触兴奋的特点(相同的极低阈值，相似的中枢潜伏期)，认为H反射对联合刺激的额外易化和单个运动单位的PSTH的迟峰都是通过相同的运动神经元前通路介导的。7.讨论了非单突触兴奋可能通过固有脊髓神经元介导的可能性。
1. The possibility that activation of low-threshold afferents in the median and ulnar nerves in man evokes an interneuronally mediated excitation of wrist flexor motoneurones was investigated. Two independent techniques were used: (i) the indirect technique of spatial and temporal facilitation of the flexor carpi radialis H reflex: (ii) the post-stimulus time histogram (PSTH) method for measurement of the firing probability of voluntarily activated motor units following different stimuli. 2. Conditioning volleys were evoked by weak electrical stimuli (to the median nerve, the ulnar nerve, the skin and cutaneous nerve branches) and by a tap to the tendon of the flexor carpi radialis muscle. 3. In the H reflex experiments the comparisons was drawn between the effects of two conditioning stimuli applied separately or together. In some experimental conditions the facilitation of the reflex evoked when combining two conditioning stimuli was larger than the algebraic sum of the effects from separate stimuli. The central latency of this additional facilitation, which is denoted ''extra facilitation'', was 3 ms. It is argued that the extra facilitation reflects summation at a premotoneuronal levels. 4. PSTHs of voluntarily activated flexor carpi radialis and flexor carpi ulnaris motor units were computed following stimulation of the median or the ulnar nerve. In 60% of the recordings the afferent volley evoked a peak of increased firing probability with a latency which was 3-6 ms longer than the monosynaptic Ia latency. 5. Both the extra facilitation of the reflex and the late peak in the PSTH were evoked from very low-threshold afferents. A contribution from Ia afferents was demonstrated in reflex experiments. Group I afferents alone are responsible for the onset of the non-monosynaptic excitation but it is probable that cutaneous afferents give a later contribution. 6. On the basis of the characteristics of the non-monosynaptic excitation studied with the two methods (same very low-threshold, comparable central latencies), it is argued that both the extra facilitation of the H reflex on combined stimulation and the late peak in the PSTHs from individual motor units are mediated through the same pre-motoneuronal pathway. 7. The possibility that the non-monosynaptic excitation may be mediated through propriospinal neurones is discussed.