THE EFFECTS OF ISOLATION-REARING ON PREFERENCE BY RATS FOR A NOVEL ENVIRONMENT

In the previous paper isolation-reared rats exhibited enhanced environ mental neophobia under some conditions in an open-field. However, prev ious work has shown that isolation-reared rats have greater preference s for a novel environment in a dimly lit enclosed box. The hypothesis examined in the present experiments was that manipulation of the intri nsic aversive qualities of such an environment, by altering lighting c onditions, could reverse the preference which isolation-reared rats ex hibit for a novel chamber. When preference for a novel chamber was exa mined in a non-aversive environment in Experiment 1, isolation-reared rats exhibited a preference for a novel environment which was enhanced compared to social controls. When tested under more aversive white li ght conditions in Experiment 2, no differences in novelty preference w ere observed between isolation-reared and socially reared rats. Thus, the increased sensitivity to novel environments by isolation-reared ra ts appears to be critically dependent on the arousing or aversive prop erties of the resting conditions. (C) 1997 Elsevier Science Inc.