Dissociation of impairment between spatial memory, and motor function and emotional behavior in aged rats

We investigated changes in learning and memory in aged rats, in relation to motor function and emotional behavior. Male Kbl Wistar aged rats (108- weeks-old) were divided into two groups, memory impaired and non-impaired, based on performance during six training trials in the Morris water maze task. Aged rats with a goal latency longer than the mean plus the 99% confidence limit of young rats, were regarded as memory impaired, whereas those with a goal latency within the range of the 99% confidence limit of the mean of young rats, were considered as memory non-impaired. Although the performance of the memory impaired aged rats in the standard test of the Morris water maze improved after six re-training trials to the level of the non-impaired aged rats and young rats, working memory impairment was evident. There were no differences in motor function and emotional behavior between the impaired and non-impaired aged rats. These results suggest that deficits of learning and memory in memory impaired aged rats can be dissociated from changes in motor function and emotional behavior.