title: Single unit activities produced in the frog spinal cord by natural stimulation of proprio- and exteroceptors.
abstract: Central branches of primary afferents, interneurons, and motoneurons were studied by extracellular microelectrodes in the frog spinal cord in situ. Responses to electrical stimulation of dorsal root fibers and ventral roots axons, as well as those evoked by natural stimulation of skin and muscle receptors were investigated. Criteria were defined to identify interneurons on the basis of their responses to natural stimuli. Apparently specific subgroups of interneurons were found which could be activated from skin mechanoreceptors or from proprioceptors. Other interneurons revealed convergence of effects of skin stimuli and passive joint movements. Some interneurons gave complex responses including excitation and inhibition from different sources. Properties of primary afferents were similar to those reported by others. Motoneurons gave rather simple responses to natural stimuli. The results provide a basis for further work on subgroups of cells affected by specific stimuli.
mesh_terms: D000200:Action Potentials; D000818:Animals; D004558:Electric Stimulation; D006614:Hindlimb; D007395:Interneurons / Q000502:physiology; D008465:Mechanoreceptors / Q000502:physiology*; D008839:Microelectrodes; D009046:Motor Neurons / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D011434:Proprioception; D011893:Rana esculenta / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*