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

The effect of environmental enrichment on conditioned freezing to contextual cues in adult Sprague-Dawley rats was examined. The freezing of both enriched-and standard-reared rats increased with the time spent in the chamber prior to shock. Both groups of rats showed equally low levels of contextual conditioning following a preshock period of 4 s and equally high levels following a 120-s preshock period. However, following a preshock period of 16 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 similar but distinctive context. Hence, in addition to forming a representation of the context in memory more rapidly than standard-reared rats, enriched-reared rats also appear to form a more complex representation. Copyright 2000 Academic Press.