11/17 Ashokan et al. / Lehmann and Herkenham

Ashokan et al. researched the effects of environmental enrichment on reducing the effects of stress through looking at changes dendritic complexity in the BLA and BDNF. They first identified the anxiolytic effects of EE on stressed animals, and then looked for the neuronal factors that caused the rescue effect. I was curious about why the authors mentioned that a running wheel was not provided. A wheel was provided in the Lehmann and Herkenham experiments. It would be interesting to see if their results changed by adding a running wheel.

Ashokan et al. concluded that environmental enrichment, even in a short period of adulthood, can support resilient behavior in mice. In the future, it would be interesting for them to test an enrichment paradigm that started after the stressful event for the research to be more translatable. Then, we would know if providing enrichment after a stressful time in a human’s life would foster resilient behavior in the future. It may be difficult to start enrichment while the human is going through stress.

Lehmann and Herkenham tested how environmental enrichment affects resilience of mice that were subjected to a social defeat paradigm and investigated the circuits involved in this process. From the cellular data, the researchers learned that the IL might be important to resilience. Lehmann and Herkenham ran behavioral tests after lesioning the IL. The EZM test yielded no significant results, and the L/D test showed a significant of infusion and an interaction between lesion and housing. Since these tests were both supposed to measure anxiety, I thought that they should have given similar results, especially since the results were similar when the mice were tested before the IL lesions. So, the lesion might affect a part of anxiety that is only relevant in the L/D test, not EZM.

I liked that it seemed like they focused on making their results as translatable as possible. They looked at brain regions in mice that were homologous to humans with depression, and the paradigm seems like it would be easy to translate humans. However, the lesion time point that I felt would most closely relate to a real world experience was before the mice got environmental enrichment. The results of the L/D, TST, FST, and SI showed that environmental enrichment after the lesion was not effective in rescuing the animals from anxiety or depressive behaviors. A lesion after environmental enrichment, however, did provide rescuing effects on these behaviors. These results suggest that in order for environmental enrichment to be an effective method of creating resilience, the human would have had to experience enrichment prior to a stressful event. This would not be useful when trying to treat a patient that experienced something stressful in the past.