Distal forelimb cross-innervation effectively induces formation of corticorubral synapses.
We investigated whether cross-innervation of the distal forelimb extensor and flexor muscles effectively induced formation of corticorubral synapses in cats. The average time-to-peak of the corticorubral EPSPs in the red nucleus (RN) neurons innervating cervicothoracic segments (C-cells) of animals with distal forelimb cross-innervation was significantly less than that of animals with elbow cross-innervation. These fast-rising corticorubral EPSPs were shown to be induced by newly formed synapses located on the proximal soma-dendritic membrane of RN neurons, indicating that distal forelimb cross-innervation is more effective for inducing synapse formation in C-cells than elbow cross-innervation. Thus corticorubral synapse formation after forelimb cross-innervation appears to be related to direct rubrospinal connections to distal forelimb motoneurons and of functional importance to RN neurons for performing voluntary distal forelimb movement.
Fujito
Yutaka
Y
Department of Physiology, Sapporo Medical University School of Medicine, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan. fujito@sapmed.ac.jp
Aoki
M
M
D000818:Animals; D002415:Cats; D002540:Cerebral Cortex / Q000502:physiology*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials; D005552:Forelimb / Q000294:innervation* / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D012012:Red Nucleus / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission