Dark and light rearing during early postnatal life impairs spatial learning of rats in Morris water maze

In early postnatal life, sensory-driven processes deeply affect structure and function of sensory cortices. Because some visual signals pass from visual cortex to the hippocampal formation, the aim of this study was to investigate the effects of change in visual experience on rat’s spatial learning and memory. This experimental study was carried out on 30 Wistar male rats (45 days old) which were randomly distributed into 3 groups; the CO (Control group) was in 12 light/12 dark cycle through birth to the end of the study, the LR (Light Reared) group was in complete lightness and the DR (Dark Reared) group was in complete darkness (n=10 for each). Using MWM (Morris Water Maze), the animals learned to find a hidden platform for 4 trials per day during 5 days. After removing the platform, spatial memory was tested at day 5 in one trial (probe trial). Our results indicated that in the learning stage, the CO rats spent less time and distance to find the hidden platform than the other groups. There was no difference between all groups in probe trial. Change in visual experience impairs spatial learning of rats in Morris water maze and their spatial memory formation is not influenced.