Currently, more than half of the world's population lives in urban communities. These communities tend to be vastly dense and, consequently, have led humans to spend more time inside, rather than out in nature (Berman et al., 2019). Continuous research in the field of environmental neuroscience reveals how environments such as urban areas and greenspace influence our brain.
Marc Berman, Associate Professor at the University of Chicago, tested the influence of urban greenspace with individuals that live in urban communities. He describes the beneficial cognitive changes that occur when we expose ourselves to nature such as improved working memory, mood, and even attention (Berman et al., 2019). However, the mechanisms underlying these changes are mostly still unknown. What is known is that nature tends to express fractal patterns, meaning that it consists of nearly endless similar patterns. Our brains process these characteristics of nature differently than scenes from urban areas. Berman describes this phenomena as putting our brains in a "low-effort state" (Berman et al., 2019). The term "low-effort" state essentially means that your brain processes images easier. Berman mentions visual stimuli tests in retinas of nonhuman species which suggest that the neurons specialized in encoding predictive stimuli process natural images differently.
Recently, mental health writer, Beth Ellwood, discussed the impact of nature and urbanization on our stress, specifically, our amygdala. Our amygdala is a structure in our brain located in the medial temporal lobe that crosses into both our hemispheres. Its primary role is processing fear stimuli and regulates emotions like anger. Her article suggests that spending an hour in nature (like taking a walk) reduces the amygdala's activity (Ellwood 2022). Ellwood referenced Sonja Sudimac’s seminal study in which amygdalic activity was measured using functional magnetic resonance imaging (fMRI) on two test groups from Berlin. One group was assigned to walk in a lively city while the other took a walk in a forest. fMRI data revealed that amygdalic activity was reduced for those who took the walk in the forest. Those who walked in the city, however, had "stable" amygdala activity (Sudimac et al., 2022). This is a particularly interesting result because it implies that, while amygdala activity is greater in urban areas, it doesn't tend to increase, hence the stability in activity. The implication of these findings indicate that urban greenspace plays an important role in reducing stress and can "increase the amygdala's threshold for activation" (Sudimac et al., 2022). A lower activation threshold, effectively, reduces the impact of urban environments on stress, leading to better mental health outcomes for those who live in cities.
References
Berman, M. G., Stier, A. J., & Akcelik, G. N. (2019). Environmental neuroscience. American
Psychologist, 74(9), 1039–1052. https://doi.org/10.1037/amp0000583. .
Ellwood, Beth. “Experiment Reveals That a One-Hour Walk in Nature Reduces Amygdala Activity,
Which May Protect Mental Health.” PsyPost, 23 Sept. 2022,
https://www.psypost.org/2022/09/experiment-reveals-that-a-one-hour-walk-in-nature-
reduces-amygdala-activity-which-may-protect-mental-health-63972. American Psychologist,
74(9), 1039–1052. https://doi.org/10.1037/amp0000583.
Sudimac, Sonja, et al. “How Nature Nurtures: Amygdala Activity Decreases as the Result of a One-Hour
Walk in Nature.” Nature News, Nature Publishing Group, 5 Sept. 2022,
https://www.nature.com/articles/s41380-022-01720-6.
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