Axonal trajectories of the nucleus reticularis gigantocellularis neurons in the C2-C3 segments in cats.
Axonal trajectories in the C2-C3 segments of the nucleus reticularis gigantocellularis neurons projecting to the lower cervical cord (C-RSNs) and excited monosynaptically from cortico- and tectofugal fibers were studied by mapping thresholds of antidromic excitation and intra-axonal staining in cats. The C-RSNs descended in various sites of the spinal funiculi, and the projection area of individual cells varied with the funicular location of the stem axon. C-RSNs descending in the ventrolateral funiculus (inRSNs) projected mainly to lamina VIII-IX, those descending in the lateral funiculus (IRSNs) mainly to laminae VI-VIII, and those descending in the contralateral funiculus (coRSNs) chiefly to laminae VIII-IX on that side. It is suggested that inRSNs and coRSNs mediate disynaptic effects from cortico- and tectofugal fibers to dorsal neck motoneurons bilaterally.
D000818:Animals; D001369:Axons / Q000502:physiology*; D002415:Cats; D004056:Differential Threshold / Q000502:physiology; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology; D009333:Neck; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D012154:Reticular Formation / Q000166:cytology / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology