Age-dependent effects of environmental enrichment on spatial reference memory in male mice

Although environmental enrichment has been shown to improve various types of memory in young and aging mice, no study has directly compared the degree to which enrichment improves memory at different ages throughout the lifespan in male mice. Therefore, the present study investigated the effects of long-term continuous enrichment in young (3 months), middle-aged (15 months), and aged (21 months) male C57BL/6 mice. Spatial reference memory was tested in the Morris water maze. Results demonstrate that 24 h/day environmental enrichment for approximately 6 weeks significantly improved spatial memory in the Morris water maze in aged males, but not in young or middle-aged males. These data also indicate that 24 h exposure to complex enriched housing conditions increases the magnitude of enrichment-induced improvements in memory among aged mice relative to those previously reported by this lab and others. (C) 2007 Elsevier B.V. All rights reserved.