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.
Opendak, M., & Gould, E. (2015). Dult eurogenesis: A substrate for experience-dependent change. Trends in Cognitive Neuroscience, XX, 1-11. Retrieved February 24, 2015.