Wednesday, November 16, 2016

11/17 Environmental Enrichment

          Ashokan et al. (2016) asked whether or not environmental enrichment reduces basolateral amygdala dendritic complexes that were increased by stress and anxiety, as well as stress-induced anxiety behaviors as a result of these molecular changes. Overall I think they were sufficient in supporting their hypothesis, but there are a few aspects of their experiments I would like to criticize. They showed that short-term environmental enrichment was sufficient enough to produce stress resiliency by continuous EE exposure over a period of about 16 days, give or take. In each experiment, the mice were exposed to chronic immobilization stress for only 2 hours a day for the first 10 days. I would've liked to have seen a more diverse set of experimental designs, such as CIS immediately preceding the behavioral test (rather than a few days before), or EE occurring for just a few days before or after exposure to CIS, and even perhaps long-term environmental enrichment paradigms. I found it rather surprising in Figure 5 how stress did not induce a significant change in serum corticosterone levels since it involves excessive secretion of corticosterone (although, there did appear to be greater levels of corticosterone in stressed animals than in control animals in the absence of EE). The fact that EE did not show any significant difference between control and stress mice can hint that EE may not affect corticosterone levels.

          I preferred the experimental design of Lehmann and Herkenham (2011)'s paper more than the previous one. Their designs were more diverse in both housing types (not only did they house mice in enriched and standard environments, but also they housed them in impoverished housing) and when the mice were exposed to the different types of housing (before or after lesions). I also like how they also included a wide variety of brain regions that are involved in abnormal activity during stress-related disorders, and how these brain structures are also found in humans as well. I wonder, since they only used short-term EE, if long-term EE would have the same effect as short-term EE or if the effects would be greater. Maybe that can be a future experiment.

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