  The occurrence of a critical period of plasticity in the visual cortex has
long been established, yet its function in normal development is not fully
understood. Here we show that as the late phase of the critical period unfolds,
different areas of cat visual cortex develop in a coordinated manner.
Orientation columns in areas V1 and V2 become matched in size in regions that
are mutually connected. The same age trend is found for such regions in the
left and right brain hemisphere. Our results indicate that a function of
critical period plasticity is to progressively coordinate the functional
architectures of different cortical areas - even across hemispheres.
