Reverse occlusion leads to a precise restoration of orientation preference maps in visual cortex.

In the visual system of young kittens, the layout of the cortical maps for ocular dominance and orientation preference converges to an equilibrium state within the first few weeks of life and normally remains largely unchanged. If during the critical period, however, patterned visual experience is restricted to only one eye for a few days, cortical neurons lose their ability to respond to stimulation of the deprived eye. We used the 'reverse occlusion' protocol together with chronical optical imaging to investigate how the profound anatomical changes accompanying monocular deprivation affect the spatial pattern of the cortical orientation preference map. We report here that after 1 week of monocular deprivation, cortical orientation maps for the deprived eye had vanished. But we also discovered that after subsequent reverse occlusion the restored orientation maps were very similar to the original maps. This demonstrates that in spite of functional disconnection of one eye after monocular deprivation, the layout of cortical orientation maps, when re-established for this eye, is not formed from scratch but is strongly influenced by previous experience.