Effects of environmental enrichment on rate of contextual processing and discriminative ability in adult rats

The effect of environmental enrichment on conditioned freezing to contextua l cues in adult Sprague-Dawley rats was examined. The freezing of both enri ched- and standard-reared rats increased with the time spent in the chamber prior to shock. Both groups of rats showed equally low levels of contextua l conditioning following a preshock period of 4 s and equally high levels f ollowing a 120-s preshock period. However, following a preshock period of 1 6 s enriched rats displayed more contextual conditioning than standard rats . That is, enriched rats appeared to process contextual information faster than their standard-reared counterparts. Enriched-reared rats also showed a greater ability to discriminate between the conditioning context and a sim ilar but distinctive context. Hence, in addition to forming a representatio n of the context in memory more rapidly than standard-reared rats, enriched -reared rats also appear to form a more complex representation. (C) 2000 Ac ademic Press.