[Interhemispheric competition during postnatal development].

The corpus callosum is a bidirectional pathway interconnecting the visual cortices on the two sides of the brain. Rearing kittens with the optic chiasm sectioned and one eyelid sutured during early development results in a functional asymmetry in this pathway. Visual input originating on the side of the brain ipsilateral to the sutured eye looses the ability to influence cells on the other side of the brain. Conversely, visual input originating on the side of the brain ipsilateral to the exposed eye markedly increases its influence in the other hemisphere. These physiologic findings are paralleled by anatomic results indicating that the terminal field of the corpus callosum is markedly expanded in the cortical hemisphere ipsilateral to the deprived eye and reduced in the other hemisphere.