Diamond, M. C., Rosenzweig, M. R., Bennett, E. L. et al. 1972. Effects of environmental enrichment and impoverishment on rat cerebral cortex. Journal of Neurobiology 3, 47-64.

The first part of this paper deals with rat brain anatomy as affected by variations of starting age and of duration of exposure to enriched (complex) or impoverished (restricted) environmental conditions. Cerebral cortical depth measurements and weights of brain samples are compared. The second part of this report is concerned with an attempt to establish the extent to which the enriched condition or the improverished condition is responsible for the histological brain changes; this is done by comparison with brains from animals in the standard colony environment. The results indicate that both larger and more extensive cortical depth effects are found in rats exposed for 30 days rather than 80 days to their respective environments. The effects of enrichment are more prominent in the dorsal cortical segments, whereas the effects of impoverishment are more evident in the lateral cortical segments. More precise localization of cortical changes is obtained by measuring the depths at many segments than by taking the weights of relatively large blocks of tissue.