Experience-dependent regulation of zif268 gene expression and spatial learning

Environmental enrichment (EE) is known to enhance the cognitive ability of rodents. To translate EE to the human condition, it is important to understand the parameters of its efficacy. In this study, we examine if the cognitive enhancement associated with EE is permanent and whether a developmental window exists for its efficacy. Rats were housed in continuous isolation (ISO), continuous enrichment (EE), enrichment from postnatal day (PN) 21-50, and then isolation from PN50-79 (PM), or isolation from PN21-50 and then enriched from PN50-79 (CW). Spatial learning ability and basal expression of the immediate-early genes zif268 and Arc as well as the NR1 subunit of the NMDA receptor were assessed. Rats housed in an enriched environment at the time of testing (EE and CW) performed significantly better in the spatial learning task than rats housed in an isolated environment at the time of testing (ISO and PM). Enhanced performance in the spatial learning task was associated with a higher expression of zif268 only in the CA3/CA4 region of the hippocampus. Our study further defines parameters that make environmental enrichment effective in enhancing learning performance and the findings may be helpful in the translation of this intervention to the human condition.