Visual cells in the pons: locus and properties
Gibson A., Baker J., Stein J., Glickstein M.
Light flashes evoke potentials widely on cerebellar vermis and hemispheres of cats. Earlier work suggests that the vermian potential is relayed principally via superior colliculus. The input to cerebellar hemispheres may arise from the cerebral cortex via a relay in the pons. In cats, visual Area II sends fibers which terminate in rostral pons. Cells in the pontine nuclei project principally to cerebellar hemispheres. The locus and visual response properties of cells in the pons were studied in the region where fibers from visual Area II terminate. Cells in this region of the pontine nuclei can be activated by visual stimuli and by no other sensory inputs. The locus of visually activated cells is coextensive with the termination of axons from visual cortex. Superior colliculus does not determine the visual properties of these rostral pontine visual cells, since colliculo pontine fibers end more caudally in pontine nuclei. Also, in cats in which large collicular lesions were made visual responsiveness of these cells in rostral pons was unchanged. Results suggest: V2 organizes responses to moving targets and relays such information to the cerebellum. If the visual input to the cerebellar hemispheres is diffuse, such diffuseness must be due to the pontocerebellar portion of the pathway. Cortical input to pons is precisely localized and cells receiving cortical input are modality specific.