Neuroscientists once contested the idea that new brain cells could be created in the adult brain, but now most agree that it is a normal part of brain development in adulthood. While neurogenesis is associated with improvements in cognitive performance, it is not always easy to create an environment that fosters neurogenesis. I was wondering why it is so difficult to create new cells in the brain and what conditions may exist that prevent neurogenesis from occurring. During my research I came around the hundreds of articles on stress and its inhibitory effects on neurogenesis, but then I came across something a little more interesting.
In a review published earlier this year, Maya Opendak and Elizabeth Gould at Princeton investigated the possibility that the inhibitory effect of stress on new cell growth in the brain has an adaptive function (Opendak & Gould 2015). Opendak and Gould (2015) specifically looked at the effect of stressful environments on neurogenesis, and how it may be beneficial to prevent cognitive improvements in circumstances where survival must be prioritized. They posited that the brain’s stress hormones, like glucocorticoid, work to prevent neurogenesis to keep the subject (human or otherwise) anxious and promote avoidance behavior (Opendak and Gould 2015). This would be beneficial in any scenario where exploration of one’s environment could mean death. Of course, an excess of stress and long-term prevention of cell proliferation could lead to significant cognitive deficits that become maladaptive (Opendak & Gould, 2015).
In support of Opendak & Gould’s (2015) adaptive hypothesis, they also found that conditions other than stress could hinder neurogenesis. For example, they cited studies that established that socially dominant rats produce more neurons than their subordinate counterparts. The dominant rats do not experience less stress, specifically they do not have lower glucocorticoid levels that could impair neuron proliferation (Opendak & Gould, 2015). This implies that the factors hindering neurogenesis are part of a broader range of circumstantial variables that require more basic brain functioning, and less cognitive enhancement. In contrast, when stress is low and humans (or other animals) are operating in a low risk environment, cognitive improvements resulting from neurogenesis will allow them to more effectively and meaningfully interact with their surroundings.
While stress being able to hinder neurogenesis in a state of nature may be beneficial, for humans in modern society it seems like it could be incredibly detrimental. I am specifically thinking of students from a wide variety of socioeconomic backgrounds attempting to learn at similar paces while experiencing starkly different out-of-school environments. This article made me think that maybe tasks that increase neurogenesis, like physical activity, could be critical in leveling the playing field among younger and older students alike. More research on this is likely necessary to investigate the possibilities of increasing neurogenesis as a means of healthy educational practices.
Works Cited
Opendak, M., & Gould, E. (2015). Dult eurogenesis: A substrate for experience-dependent change. Trends in Cognitive Neuroscience, XX, 1-11. Retrieved February 24, 2015.
On Psychology and Neuroscience 
It was interesting to learn how stress can prevent basic pathways in neuron creation. When studying about neural plasticity and neurogenesis, we should not only look at how “enriched” the environment is, and how capable the animal is able to “learn” (form new neurons/neuron connections), but we should also take into consideration ‘stress levels’ as another factor that could affect our ability to “learn.”
I was especially intrigued to learn that neurogenesis is hindered in most/all stressful situations. Hindering neurogenesis (the ability to form new neurons and synaptic connections) sounds like a survival disadvantage, especially if the “stressful condition” involves a change of environment or requires learning of the surrounding environment so that the animal could survive. I would have guessed that short-term stress would allow some neurogenesis to take place so that they could learn about the new environment better. However, it was interesting to know that this is not the case.
As I was reading this blog post, I was curious to learn more about glucocorticoid and how the neurotransmitter works specifically to stop/slow down neurogenesis, and how that leads to heightened anxious and avoidance behaviors.
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I really enjoyed the last point which connected stress to our modern day society. If stress and glucocorticoid are inhibiting neurogenesis it seems that we should revamp our education system. As an undergraduate student, not a day goes by when I am not worrying about my ext essay or exam. It is scary to realize that this stress might be detrimental to brain growth. If stress inhibits neurogenesis it is easy to imagine a self perpetuating cycle where more stress leads to less neurogenesis ultimately leading to more stress. I would be very interested in a more quantitative analysis of the effects of stress on the brain.
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