Developmental interactions between the corpus callosum and the visual system in cats.
The neonatal corpus callosum is involved in the development of pathways or mechanisms that coordinate the inputs from the two eyes. Several related visual functions are permanently altered by the absence of the callosum during early development. As determined behaviorally and by visual evoked potentials, the normal amount of 90 degrees of the visual field in which both eyes respond to stimulation is almost completely eliminated. Also, there is a reduced number of binocular cells in striate cortical regions representing most of the visual field. In addition, behaviorally measured visual acuity is reduced. Changes in acuity and striate binocularity only result when a callosal section occurs during a critical period of the first postnatal month, and the earlier the surgery, the greater the changes. The lack of myelination during the first postnatal month indicates that the conduction properties of the callosum are poorly developed during its critical period. The pattern of callosal connectivity is probably significant for its role in development, but not all callosal fibers are necessary for normal visual development. Developmental plasticity of callosal connections has been demonstrated for striate cortex, but now it has also been demonstrated for the claustrum. Thus, the callosal role in regions representing both central and peripheral visual field, in neocortical and non-neocortical brain areas should be reassessed.
Elberger
A J
AJ
Department of Anatomy and Neurobiology, University of Tennessee, Memphis 38163.
D000375:Aging / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D002415:Cats; D003337:Corpus Callosum / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D005074:Evoked Potentials, Visual; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology; D014792:Visual Acuity; D014793:Visual Cortex / Q000502:physiology; D014794:Visual Fields; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*