Illert M, Lundberg A, Tanaka R
Exp Brain Res. 1976 Dec 22;26(5):521-40. doi: 10.1007/BF00238825.
With intracellular recording from forelimb motoneurones the spatial facilitation technique has been used to investigate interaction between descending pathways and forelimb afferents. As previously shown for the hindlimb, pyramidal volleys effectively facilitate interneuronal transmission in reflex pathways from different primary afferents. Evidence is presented suggesting disynaptic excitation from corticospinal fibres of interneurones in the reciprocal Ia inhibitory pathway. Interneurones of other reflex pathways from group I muscle afferents recieve monosynaptic pyramidal excitation. During pyramidal facilitation volleys in cutaneous afferents may evoke PSPs in motoneurones after a central delay of 1.3 ms suggesting that the minimal linkage is disynaptic. Information regarding convergence on the neurones intercalated in the disynaptic cortico-motoneuronal pathway was obtained by investigating the effect from primary afferents and from other descending pathways on the disynaptic pyramidal EPSPs. Volleys in cutaneous and group I muscle affferents facilitate transmission in the disynaptic cortico-motoneuronal transmission with a time course showing oligosynaptic (probably monosynaptic) action the intercalated neurone. Rubrospinal volleys likewise effectively facilitate disynaptic cortico-motoneuronal pathway with a time course showing oligosynaptic (probably monosynaptic) action on the intercalated neurone. Rubrospinal volleys likewise effectively facilitate disynaptic cortico-motoneuronal transmission with a time course showing monosynaptic action on the intercalated neurone. Spatial facilitation experiments involving three tests revealed that those intercalated neurones which receive convergent monosynaptic excitation from corticospinal and rubrospinal fibres are excited also from cutaneous forelimb afferents. Disynaptic cortico-motoneuronal transmission was also monosynaptically facilitated by stimuli in the dorsal mesencephalic tegmentum probably activating tectospinal fibres. Disynaptic, presumed tectospinal EPSPs were facilitated from cutaneous forelimb afferents. The convergence onto the neurones intercalated in the disynaptic excitatory cortico-motoneuronal pathway suggests that these neurones integrate the activity in different descending pathways and primary forelimb afferents.
通过对前肢运动神经元进行细胞内记录，运用空间易化技术来研究下行通路与前肢传入神经之间的相互作用。正如先前在后肢所显示的那样，锥体束冲动能有效地促进来自不同初级传入神经的反射通路中的中间神经元传递。有证据表明，在相互抑制的Ia抑制通路中，中间神经元的皮质脊髓纤维存在双突触兴奋。来自I类肌肉传入神经的其他反射通路的中间神经元接受单突触锥体束兴奋。在锥体束易化过程中，皮肤传入神经的冲动在经过1.3毫秒的中枢延迟后，可能会在运动神经元中诱发突触后电位，这表明最小的联系是双突触的。通过研究初级传入神经和其他下行通路对双突触锥体束兴奋性突触后电位的影响，获得了关于双突触皮质运动神经元通路中插入神经元的汇聚信息。皮肤和I类肌肉传入神经的冲动促进了双突触皮质运动神经元的传递，其时程显示对插入神经元有少突触（可能是单突触）作用。红核脊髓束冲动同样有效地促进了双突触皮质运动神经元通路，其时程显示对插入神经元有少突触（可能是单突触）作用。红核脊髓束冲动同样有效地促进了双突触皮质运动神经元传递，其时程显示对插入神经元有单突触作用。涉及三项测试的空间易化实验表明，那些接受皮质脊髓和红核脊髓纤维汇聚单突触兴奋的插入神经元也会被前肢皮肤传入神经兴奋。中脑背侧被盖区的刺激可能激活顶盖脊髓纤维，也能单突触促进双突触皮质运动神经元传递。双突触的、推测为顶盖脊髓的兴奋性突触后电位受到前肢皮肤传入神经的易化。双突触兴奋性皮质运动神经元通路中插入神经元的汇聚表明，这些神经元整合了不同下行通路和前肢初级传入神经的活动。
