Cerebral changes in rats exposed individually to an enriched environment.

Gave 275 male Berkeley S1 rats injections of saline or 2mg/kg of methamphetamine. Ss either remained in the home cage or were placed individually into an enriched environment for 2 hr/day during the light or dark hours. Ss placed singly in large enriched-environment cages over a 30-day period were different from home-cage control littermates in weights of brain sections and in brain-enzyme activities. These differences were small, however, unless S's interaction with the stimulus objects was facilitated. Such priming was accomplished by placement in the dark under the influence of methamphetamine. It is concluded that social stimulation, which previously has always been included in the enriched condition, is unnecessary. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)