The effects of an enriched environment on the histology of the rat cerebral cortex

✍ Scribed by Marian C. Diamond; David Krech; Mark R. Rosenzweig

• Publisher: John Wiley and Sons
• Year: 1964
• Tongue: English
• Weight: 734 KB
• Volume: 123
• Category: Article
• ISSN: 0021-9967
• DOI: 10.1002/cne.901230110

✦ Synopsis

Recently, it has been reported by Rosenzweig, Krech, Bennett, and Diamond ( ' 6 2 ) that increasing the environmental complexity and training of rats resulted in measureable changes in brain chemistry and in brain weight. More specificially, some of the results have demonstrated that the cerebral cortex from rats subjected to training showed not only an increase in acetylcholinesterase but also an increase in weight. It is this weight increase which concerns us at present. Though small, 7.6% in the samples from the visual cortex and 3.3% in the samples from the somatosensory cortex, the increase was consistent and repeatable since the cortical weights from trained animals exceeded those from untrained and isolated rats in 79% of the cases for the visual area (53 of 67 pairs) and in 64% for the somatosensory area (43 of 67 pairs) (Rosenzweig, Krech and Bennett, unpublished data). In contrast to the cortical weight increase, there were no changes in weight in the subcortex. Also it might be pointed out that the body weights of the isolated rats were greater than those of the trained rats by approximately 7 % .

Heretofore the brain has generally been considered incapable of macroscopic physical changes as a consequence of alterations in experience. Because of the findings cited above, anatomical examinations were considered essential to determine possible causes for this increase in cortical weight.