The efficacy of brief periods of reverse occlusion in promoting recovery from the physiological effects of mononuclear deprivation in kittens.

The relative effect of short daily periods of reverse occlusion in promoting recovery from the physiological effect of monocular deprivation in kittens were examined with a view to identifying a neurophysiological basis for the visual improvement observed with minimum occlusion therapy in amblyopia. Kittens were monocularly deprived from near birth until 5 weeks of age, at which time they were reverse-sutured and housed in total darkness. Each kitten received a short period of visual exposure through its initially deprived eye each day for either a fixed number of days or for a constant total visual exposure spread over a different number of exposure sessions. Electrophysiological recordings from single cells in the visual cortex were made the day after the last visual exposure. Kittens that received daily periods of reverse occlusion as brief as 30 min for 20 days showed a substantial degree of reversal of cortical ocular dominance. Other experiments indicated that 20 hr of reverse occlusion distributed over a number of brief daily sessions was far more effective in promoting physiological recovery than the same total period of exposure imposed in only two sessions. In general these results suggest that a given period of reverse occlusion may be more effective in promoting recovery with distributed than with massed periods of occlusion.