Environmental Enrichment Influences Survival Rate and Enhances Exploration and Learning But Produces Variable Responses to the Radial Maze in Old Rats

Wistar rats at 7 (mature), 16 (aging), and 22 (old) months of age spent 70 days in normal laboratory (Social), impoverished (Isolated) or dynamic Enrichment cages. The Enriched cage emphasized spatial re-arrangements of significant items, and the learning of new routes. Subsequently,, Enriched rats at all ages entered a novel environment and escaped from a bright light with significantly shorter latencies than rats from either of the other environments. Mature, aging and some of the old Enriched rats also significantly outperformed their Isolated and Social counterparts in the radial maze. However old Enriched and Isolated animals showed significant variability in relation to the measure of the proportion reaching criterion on this task, and a significantly lower proportion than of old Social rats reached criterion. Enriched rats had a significantly higher survival rate than Social and Isolated animals. These findings are discussed in terms of learning efficiency and behaviors that conserve energy and thereby enhance survival. (C) 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 564-578, 2009.