Effects of early spatial training on water maze performance: a longitudinal study in mice.

The aim of the present study is to establish whether in mice the effects of an early experience in the Morris water maze are maintained after a long period. A longitudinal study was performed in which mice of two different strains (NMRI and C57) received spatial training at 2 months of age and their performance was re-evaluated 8 and 16 months later. In both strains, results showed a beneficial effect of prior experience on this spatial memory task even 8 months after the initial training. At 18 months of age, performance of C57 mice that were trained at 2 months of age for the first time was similar to those who received their first training at 10 months of age. These findings suggest that the beneficial effect of previous training could be limited by time. In addition, water maze performance of 18 month-old C57 mice did not differ from their earlier performance when they were 10 months of age, which would indicate that experience in this task could prevent some of the age-related spatial learning deficits observed in mice.