Much research indicates that exposure to nature and natural environments are effective in reducing stress and improving mental well-being. Now, we have insight into the neurophysiological mechanism. It lies within one of the oldest parts of the human brain.
MRI image of the posterior cingulate cortex (highlighted in green). Photo credit: Geoff B Hall.
As we indicated in past blogs, a significant amount of research from a number of scientific disciplines concludes that exposure to nature-containing environments enhances mental health and improves recovery from stress. Now, we may have a neurophysiologic mechanism for that effect.
Researchers from Hong Kong studied 44 participants by showing them 3D images of urban neighborhoods that varied according to the amount of green space. The images were of midwestern US towns that were controlled for brightness and color saturation but varied in the percent of green space. After viewing the images, the participants were given a functional MRI scan to see what portions of the brain were activated by the images. Two weeks later, the participants were questioned about their preferences for each image and their level of self-reported stress.
What the researchers found was that an evolutionarily ancient part of the brain—the cingulate gyrus—was the region primarily activated by the green environments. Moreover, the amount of activity corresponded directly to the amount of green space. That activation was felt to be beneficial, leading to stress-reduction and attention restoration.
We now have suggested neurologic mechanism for the salutary effects of nature on well-being observed previously and elsewhere.
In an interview with PsyPost: https://www.psypost.org/2020/11/neuroimaging-study-provides-new-details-on-the-link-between-stress-reduction-and-green-urban-landscapes-58662 the researchers explained: “It turns out environments … with varying degrees of green-cover, activate a primitive part of the brain – the posterior cingulate. This region is particularly intriguing as it is a part of a larger (limbic) system that is known for its role in serving motivation- and emotion-related responses, but also has extensive connections to executive (e.g., decision-making) and attentional nodes in the brain,” the researchers explained.
“When we varied the green-content contained in our scenes, we saw corresponding changes in the activity of this same region that was surprisingly well-matched to the subjects’ own reported stress-ratings after viewing these same images. It appears then, that the cingulate is a key area that serves our (human) sensitivity to green-spaces, and acts as an early driver that ultimately interfaces with stress regulatory responses in the neuroendocrine system.”
These stress regulatory responses originate from a primitive part of the brain and have undoubtedly evolved over millions of years. The inhibition of these responses may not be under voluntary control (personal speculation). In other words, we may not be able to stop ourselves from relaxing and feeling better in response to the natural environment. But who would want to?
The original study can be found here: https://www.sciencedirect.com/science/article/pii/S1053811920310405
Comments