Illert M, Tanaka R
Exp Brain Res. 1978 Jan 18;31(1):131-41. doi: 10.1007/BF00235810.
A previously described inhibitory trisynaptic cortico-motoneuronal pathway (Illert et al., 1976a) was analysed in order to identify the two relay stations. Intracellular recording was made from motoneurones to elbow muscles. Corticospinal fibres were stimulated in the contralateral medullary pyramid. Pyramidal IPSPs were abolished by a transection of the corticospinal tract in C2 but remained after a corresponding lesion in C5. After a C5 lesion pyramidal volleys facilitated transmission in the Ia inhibitory pathway with a time course suggesting disynaptic excitatory action on the Ia inhibitory interneurones. The trisynaptic pyramidal IPSPs were depressed by volleys in the appropriate recurrent motor axon collaterals as would be expected if these IPSPs were mediated by Ia inhibitory interneurones. It is concluded that trisynaptic cortico-motoneuronal inhibition is evoked by consecutive activation of propriospinal neurones in C3--C4 and segmental Ia inhibitory interneurones.
为了确定两个中继站，对先前描述的抑制性三突触皮质 - 运动神经元通路（Illert等人，1976a）进行了分析。从支配肘部肌肉的运动神经元进行细胞内记录。在对侧延髓锥体刺激皮质脊髓纤维。在C2水平切断皮质脊髓束后，锥体抑制性突触后电位（IPSPs）消失，但在C5水平进行相应损伤后仍保留。在C5损伤后，锥体冲动促进了Ia抑制性通路的传递，其时程提示对Ia抑制性中间神经元有双突触兴奋性作用。正如预期的那样，如果这些IPSPs是由Ia抑制性中间神经元介导的，那么三突触锥体IPSPs会被适当的回返运动轴突侧支的冲动所抑制。结论是，三突触皮质 - 运动神经元抑制是由C3 - C4节段的脊髓 propriospinal 神经元和节段性Ia抑制性中间神经元的连续激活所诱发的。
