Delayed non-matching to position performance in aged hybrid Fischer 344 x brown Norway rats: a longitudinal study.

In this study, the effects of aging on the performance in a delayed non-matching to position (DNMTP) task were investigated longitudinally in hybrid Fischer 344 x Brown Norway rats. The rats were first trained to perform the task. Subsequently, their performance was assessed monthly from 28 to 34 months of age. The measures of responding on the DNMTP schedule did not decrease in the course of the study. After the last DNMTP test, choline acetyltransferase (ChAT) activity and glial fibrillary acidic protein (GFAP) content were measured in frontal cortex and hippocampus. We found that higher levels of GFAP in the frontal cortex, but not hippocampus, were associated with a poorer performance in the DNMTP task. Our findings support the notion that repeated testing prevents the age-related decline in cognitive functions that has been reported in cross-sectional studies. Pathology of the frontal cortex seems to predict a faster rate of forgetting in aging rats.