Behavioral persistence following switchovers between environmental enrichment and impoverishment in mice

Weanling mice were reared in environmental enrichment and/or impoverishment conditions for 2 months. In the 1st experiment, mice were switched from 1 environment into the other after 1 month, and maintained in the opposite environment for 2 or 4 weeks. Switched and nonswitched groups were compared to establish whether the effects of the initial environmental exposure would persist through later opposite environmental experiences. The performance of switched groups tended to differ from that of all nonswitched groups: little behavioral persistence was found. In the 2nd experiment, mice were switched every 7, 14, or 28 days over a 2-month period. These procedures yielded several types of behavioral outcomes; however, no behavioral persistence was evidenced. The data indicate that early life experiences in a particular level of environmental complexity need not permanently modify behavior.