Long-lasting behavioral and dendritic spine deficits in the monocularly deprived albino rat

Abstract

Monocular deprivation in the rat from the time of normal eye opening until 45 days of age significantly reduces the density of dendritic spines in visual cortex contralateral to the deprived eye. In addition, these animals are severely impaired in their ability to discriminate complex visual pattern using the deprived eye. In the present experiment we tested the ability of monocularly deprived rats to recover from these deficits if given 30 days of visual experience with the deprived eye beginning at 45 days of age. Animals to be tested behaviorally were trained to discriminate between columns and rows of 5-mm squares. We found that rats cross-sutured at 45 days of age and given 30 days of visual experience with the deprived eye were not significantly different from animals who began training within 2 days of cross suture. Both groups were significantly impaired in the acquisition of this discrimination relative to animals trained using their nondeprived eye. Two groups of animals were examined to assess the effects of 30 days of experience on dendritic spine density in the deprived hemisphere. One group was killed immediately at 45 days of age, the other group had the deprived eye opened at that time and then had 30 days of visual experience prior to killing. No significant recovery in spine density was found. These results have implications for a possible structure-function relationship between dendritic spines and visual behavior in the rat.