Manufacturing Resiliency: An Investigation in Environmental Enrichment

The papers this week took very different approaches in designing experiments to test whether or not environmental enrichment (EE) can create resiliency to different forms of stress and stress effects.

The Ashokan et. al. paper used chronic immobilization stress (CIS) and countered it with EE. They chose to start the EE exposure at the same time that the CIS started. This kind of approach can be transferable to human models of chronic life stress. This approach would be analogous to an individual who is fortunate to have a wide variety of choice and enriching activities in their lives at the time that they begin to experience chronic stress. Perhaps this would not be representative of someone who comes from a low economic background and cannot afford such activities and might experience chronic stress from working multiple jobs. This group of researchers also made an interesting choice in using head dips as a measure of "active coping" behavior. To me, this seems like they are anthropomorphizing their lab animals to an inappropriate extent. Because of the non-specificity of the head dipping behavior, it seems to me that these animals could likely be exploring their environment.

The Lehmann and Herkenham on the other hand, used social defeat stress and countered it with EE. These researchers also chose to vary the time at which they gave the EE exposure, and the EE exposure never actually overlapped with the stressful experience. Because of this they were simulating a situation more similar to an individual who may have had a great experience a few days before experiencing trauma. However, this experiment is fundamentally different because the stress at hand is acute and not chronic. Although these two groups found that EE had similar effects in creating a resilient phenotype, the mechanism for this process was probably different.

On a final note, neither of these papers considered female animals in their experiments. I found this disappointing (as usual) but especially since both of these papers are fairly recent. At this point we understand that females are just simply different than males and furthermore, that many mental disorders occur more frequently in females than males.