The effect of pyramidal stimulation upon tail muscle motoneurons in the decerebrate cat

This study aimed to determine the effects of the corticospinal tract (CST) on the motoneurons innervating the tail muscles in cats. The stimulation of the pyramidal tract predominantly evoked excitatory postsynaptic potential s (EPSPs; 48/90 motoneurons: 53%). Single-pulse stimulation produced EPSPs in 18 of 48 motoneurons, but double shocks evoked postsynaptic potentials i n most of the remaining cells (26/48). Monosynaptic excitatory connections between pyramidal tract fibers and tail motoneurons were confirmed in 4 mot oneurons. Inhibitory postsynaptic potentials (IPSPs) were recorded from mot oneurons innervating long tendinous tail muscles (7/90: 8%) and the shortes t neuronal pathways of IPSPs were shown to be disynaptic pathways. Interact ions between the CST and reflex pathways from low-threshold muscle and cuta neous afferents innervating the tail and hindlimbs were observed. (C) 2000 Elsevier Science Inc.