Visual (optokinetic) and somesthetic inputs to the cerebellum of bilaterally labyrinthectomized frogs.
Unitary responses to visual (optokinetic) and somesthetic (cutaneous and propioceptive ) stimulation were recorded from the Purkinje cell layer of the cerebellum of acute (up to 30 h) and chronic (30-90 days) bilaterially labyrinthectomized frogs. Simple spikes from Purkinje cells as well as activity from cells without complex spikes were considered in this paper. The properties of the response and the distribution (restricted to the dorsal rim and auricular lobes) of the units sensitive to optokinetic stimulation of labyrinthectomized frogs, both acute and chronic, were similar to those previously reported for normal animals. The properties of the responses to somesthetic neck and limb stimulation remained similar to those of normal animals. However, there was an increase in the number of units responsive to somesthetic stimulation within the dorsal half of the corpus cerebelli (including the dorsal rim), a region experimentally deprived of vestibular afferents, neck responsive units were 33% of the total in acutely and 61% in chronically labyrinthectomized animals (compared to 5% in normal). Limb responsive units were 49% in acute and 65% in chronic animals (compared to 12% in normal). A consequence of the increase in somesthetic input was convergence of optokinetic and somesthetic inputs at the level of single units within the dorsal rim, totally absent before the lesion. The results suggest that the somesthetic spinal input might substitute for at least some features of the vestibular input to the cerebellum in bilaterally labyrinthectomized frogs.
D000200:Action Potentials; D000818:Animals; D001931:Brain Mapping; D007758:Ear, Inner / Q000502:physiology*; D005121:Extremities / Q000294:innervation; D009333:Neck / Q000294:innervation; D009760:Nystagmus, Physiologic; D011689:Purkinje Cells / Q000502:physiology*; D011892:Rana catesbeiana; D012677:Sensation / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*