The purpose of this study was to examine the effect of task experience, long-term dietary restriction and aging on spatial cognition. In experiment I, nineteen rats were divided into restricted (n= 10) or ad libitum feeding (n=9) groups at 2.5 months of age, then repeatedly trained in Morris water maze task (reference memory task) and delayed-matching-to-place (DMTP) task (working memory task). Dietary conditions did not affect in performing both tasks. However, deteriorated effect of aging was found in performing DMTP task. These results suggest that repeated task experiences protect rats from age-related reference memory deficits, but not from working memory deficits. Experiment 2 compared the performance of young (n = 8) and aged (n = 4) rats in object exploration task. Young rats reacted to both spatial and nonspatial changes in objects, whereas aged rats reacted only to nonspatial change. Thus, it is suggested that the ability to recognize spatial changes is impaired in aged rats.

Key words: Task experience; Dietary restriction; Longitudinal design; Cross-sectional design; Reference memory; Working memory; Spatial learning; Aging; Rats