The minimum extent of corpus callosum connections required for normal visual development in the cat.

The corpus callosum and its role in the development of the cat visual system was studied in terms of the minimum group of intact callosal fibers needed for normal visual development to result. Additionally, the fate of these surviving callosal fibers was studied morphologically to determine whether the resulting pattern of connectivity could account for the subsequent visual development. Incomplete corpus callosum sections were made in cats within the first two postnatal weeks, a time period when a complete callosum section results in permanent visual deficits. Visual development was assessed as a function of visual acuity, and connectivity of the intact callosal fibers was defined using the retrograde tracer, horseradish peroxidase. The results indicate that only a portion of the visual corpus callosum fibers need to be intact during the critical period of corpus callosum development in order for normal callosal connectivity and a normal visual system to result.