Serial pattern learning in senescent rats: a comparison of acquisition performance with young and...

The acquisition of a serial pattern was assessed in young (3-month), senescent (24-month), and hippocampal-lesioned rats. All animals were trained for 25 days on a four-element, nonmonotonic pattern consisting of 14, 0, 3, and 7 food pellets, respectively. Young rats were capable of distinguishing among the elements of the series, with the exception of the 3- and 7-pellet elements, as indexed by running times. Conversely, the senescent rats were largely incapable of patterned responding, and the tracking performance of the hippocampal-lesioned rats was intermediate between those of the young and old rats. Results are discussed in terms of the possible changes that accompany aging in rodents, including age-related changes in the hippocampal system.