Environmental enrichment reduces novel exploration-induced Arc expression in the dorsal blade of the dentate gyrus, but not the ventral blade. A, Confocal images showing scattered Arc-positive neurons (red) in the dorsal blade (NeuN is green). CE caged rats showed a trend towards having more cells expressing Arc, but this was not significant. Exploration caused an increase in Arc-positive neurons in SC rats, and a decrease in CE rats. B, Quantification of Arc-positive neurons in the dorsal blade. Exploration induced Arc expression in significantly more neurons in SC rats compared to CE rats. *, p<0.05. C, Confocal images showing Arc-positive neurons in the ventral blade. CE and SC rats had similar numbers of Arc-positive neurons in both the caged and exploration conditions. D, Quantification of Arc-positive neurons in the ventral blade. Both CE and SC rats showed a modest increase in the number of Arc-positive neurons following novel exploration, but no significant differences were observed in any condition.