Response properties and visual receptive fields of climbing and mossy fibers terminating in the flocculus of the monkey.
Response properties and visual receptive fields of climbing fibers and mossy fibers terminating in the cerebellar flocculus were studied in monkeys trained to fixate a stationary visual target. Among a total of 429 climbing fiber-related units (climbing fibers and complex spikes of Purkinje cells), 20 (4.9%) showed cyclic modulations in firing in response to sinusoidal retinal-slip velocities. Their receptive fields always included the fovea. Among 485 mossy fibers, 64 (13%) responded to the visual stimulation. Of the 64 visually responsive mossy fiber units, 39 (61%) responded exclusively to the retinal-slip velocity (visual mossy fibers and the remaining 25 mossy fibers (39%) responded also to the eye and head velocities (visuomotor mossy fibers). Receptive fields for 17 visual mossy fibers (17/39 or 44%) were within 10 degrees of fixation and those for 22 others (56%) were in the periphery. Receptive fields for all 25 visuomotor mossy fibers were in the periphery. Each mossy fiber unit had a unique velocity-tuning curve and, therefore, the response patterns of individual mossy fibers were different depending on the range of their velocity sensitivity and on the retinal-slip velocity applied.
D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000502:physiology; D002531:Cerebellum / Q000502:physiology*; D008254:Macaca nemestrina; D009039:Motion Perception / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D010775:Photic Stimulation; D011689:Purkinje Cells / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*