The Influence of Enriched Environments on Learning and Memory Abilities in Group-Housed SD Rats

  • Dorte B Sørensen Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen
  • Lars F Mikkelsen Novo Nordisk A/S, Animal Unit
  • Sanne G Nielsen Lundbeck A/S
  • Annette K Ersbøll Department of Epidemiology, Faculty of Life Sciences, University of Copenhagen


Six traditional behavioural tests were done to evaluate the impact of inanimate enrichment on group housed  animals. The study was performed in three parts to prevent the animals’ previous experience influencing the  behavioural tests. Three traditional housing environments with increasing levels of standardized inanimate  enrichment were evaluated with regard to the effect on activity, fear, learning and memory abilities in  socially housed rats. 

The basic activity level of the animals was assessed using the open-field test. This test was combined  with an amphetamine challenge test. The level of anxiety was evaluated by use of the elevated plus maze  test. Secondly, a Morris water maze study was done to assess spatial learning abilities. Thirdly, two more  complex learning ability tests were performed, namely the water Y-maze and the conditioned avoidance  task. 

The different housing conditions did not influence the level of activity, the level of anxiety or the response  to amphetamine. Neither did the differences in housing conditions influence the learning abilities of the  animals in the Morris water maze or the Y-maze. However, in the conditioned avoidance task, rats housed  in the extra-enriched environment demonstrated significantly fewer avoidances than rats housed under nonenriched  conditions.