REARING ENVIRONMENT AND RADIAL MAZE EXPLORATION IN MICE

The effect of an enriched rearing environment on exploration of 4- and 8-arm radial mazes was investigated in CD-1 mice. Subjects in enriche d (EC) and standard (SC) environmental conditions were socially reared with the exception that various objects and a running wheel were adde d into the EC cages. Non-deprived subjects were allowed to explore ind ividually an appropriate maze for 10-min periods on two successive day s (Days 1 and 2 of the experiment). After the second exploration sessi on subjects were deprived of water for 12 h before the test which was administered on Day 3 of the experiment. Subjects from both groups per formed similarly in the 4-arm radial maze, finding the arm containing water with comparable latency and erroneous entries to other, not cont aining water, arms. However, the more complex, 8-arm radial maze signi ficantly differentiated the behaviour of both groups. EC subjects show ed faster habituation to the maze than SC subjects, decreasing signifi cantly their locomotor behaviour during second exploratory session. Du ring the test, EC subjects found and drank water within significantly shorter time, making fewer errors. It is suggested that subtle behavio ural changes caused by different rearing environments might be more re adily detectable in the early phases of solving more complex behaviour al tasks by mildly motivated animals.