抄録
In the rat, some findings have been taken to suggest the existence of monosynaptic cortico-motoneuronal (CM) connections. Since this connection is believed to be largely responsible for the ability to make independent digit movements in primates and man, it has been inferred that the monosynaptic CM connection in the rat is likewise important for skilled prehension. We compared intra- and extracellular recordings from forelimb motoneurones in the rats anaesthetized with intravenous injection of α-chloralose and immobilized with gallamine triethidide and artificially ventilated rats. No monosynaptic CM EPSPs were recorded. Instead, we found that the fastest descending excitation in forelimb motoneurones was disynaptically mediated via a cortico-reticulospinal pathway and slowly conducted excitation via corticospinal fibres and segmental interneurones. The findings stress the importance of di- and trisynaptic excitatory corticofugal pathways to forelimb motoneurones in the control of skilful digit movements. [Jpn J Physiol 54 Suppl:S183 (2004)]
