Longitudinal study on age-related changes of working and reference memory in the rat.

Age-related changes of working memory and reference memory were examined using different age groups of Fischer 344 rats (cross-sectional study) and one group of the same strain which was repeatedly tested at different age points (longitudinal study). Delayed non-matching test in a T-maze revealed 3 points as follows: (1) since motivation by food deprivation in the task performance seemed to decrease with aging, it was needed to adjust the food deprivation level so as to attain a similar degree of motivation in different age groups; (2) scores in reference memory task remained very high in the aged in both cross-sectional and longitudinal studies; and on the other hand (3) performance of working memory task declined with aging to the same degree in both cross-sectional and longitudinal studies, suggesting that working memory progressively deteriorates in advancing age.