title: Prior activity influences the velocity of impulses in frog and cat optic nerve fibers.
abstract: Under normal visual stimulation, simultaneous recording from ganglion cells in the retina and from the axons of these cells in the brain revealed activity-dependent differences in the velocity of impulse propagation. In frog ganglion cells, spikes initiated 5-500 ms after a previous impulse showed supernormal increases in conduction velocity of up to 17%; spikes initiated 500-2000 ms after a previous one traveled more slowly than a spike initiated after a long period of rest. Cat ganglion cell impulses showed much smaller supernormality (maximum 3%), but exhibited pronounced slowing due to refractoriness and long-term fatigue associated with their high levels of spontaneous activity.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D005074:Evoked Potentials, Visual; D005829:Geniculate Bodies / Q000502:physiology; D009412:Nerve Fibers / Q000502:physiology*; D009431:Neural Conduction; D009900:Optic Nerve / Q000502:physiology*; D011894:Rana pipiens; D011930:Reaction Time / Q000502:physiology; D012032:Refractory Period, Electrophysiological; D012165:Retinal Ganglion Cells / Q000502:physiology; D013477:Superior Colliculi / Q000502:physiology; D009435:Synaptic Transmission; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*