Pierrot-Deseilligny E, Morin C, Bergego C, Tankov N
Exp Brain Res. 1981;42(3-4):337-50. doi: 10.1007/BF00237499.
Variations in the H-reflex of soleus, tibialis anterior, quadriceps and short head of biceps femoris muscles were studied in normal man, preceded by a conditioning stimulus applied to either gastrocnemius medialis, the inferior branch of soleus or the common peroneal nerve. The observed variations were evoked by low threshold afferents, had a very short latency suggesting oligosynaptic linkage and disappeared during a selective ischaemic blockade of group I fibres; they were therefore regarded as due to group I fibre stimulation. Biphasic variations were observed in almost all cases: evidence is presented that the early low threshold effects, facilitatory for synergistic and inhibitory for antagonistic motoneurone pools, are due to stimulation of Ia fibres, while the subsequent opposite effects which had a slightly higher threshold are Ib in origin. Even though the pattern of projections of group I fibres from ankle flexors and extensors is qualitatively the same in normal man as in the spinal cat, large quantitative differences are observed; in normal man the effects of group I fibres from ankle flexors and extensors upon close synergistic and direct antagonistic motoneurone pools are weak, and often negligible, whereas they are extremely potent upon quadriceps motoneurones.
在正常人体中，研究了比目鱼肌、胫骨前肌、股四头肌和股二头肌短头的Hoffmann反射（H反射）的变化，在施加条件刺激之前，先对内侧腓肠肌、比目鱼肌下支或腓总神经施加条件刺激。观察到的变化由低阈值传入神经诱发，潜伏期很短，提示为少突触联系，并且在I类纤维的选择性缺血性阻断期间消失；因此，它们被认为是由于I类纤维刺激所致。几乎在所有情况下都观察到双相变化：有证据表明，早期的低阈值效应，对协同运动神经元池起易化作用，对拮抗运动神经元池起抑制作用，是由于Ia纤维的刺激所致，而随后阈值略高的相反效应则起源于Ib纤维。尽管在正常人体中，来自踝关节屈肌和伸肌的I类纤维的投射模式在性质上与脊髓猫相同，但仍观察到很大的数量差异；在正常人体中，来自踝关节屈肌和伸肌的I类纤维对紧密协同和直接拮抗运动神经元池的影响较弱，而且往往可以忽略不计，而它们对股四头肌运动神经元的影响则极为强大。
