A multitude of studies have shown that the interaction of humans with nature generates several positive effects on health, both physically and psychologically. A recent review of these studies (in French), recently carried out by our team, revealed that these beneficial effects are particularly compelling with regard to the reduction of stress and anxiety that results from an interaction with a natural environment.
Decreased activity of the amygdala
To better understand the mechanisms involved in this nature-mediated stress reduction, a team of German researchers investigated the potential involvement of the amygdala, a region of the brain that plays a predominant role in the stress response.
In this study, the researchers recruited 63 participants and randomly divided them into two groups: 1) a “city” group, in which the volunteers (31 participants) had to walk for one hour in an urban area (a commercial street in Berlin) and 2) a “nature” group, in which the volunteers (32 participants) also had to walk for an hour, but this time in nature (the Grunewald forest, located southwest of Berlin).
By measuring the activity of the amygdala of all participants using functional magnetic resonance imaging (fMRI), before and after their assigned route, the researchers observed major differences between both groups: while walking in urban areas had no measurable effect, walking in the forest caused a significant decrease (about 50%) in participants’ amygdala activity. Moreover, this effect was observed equivalently when the participants were exposed to images of neutral faces or to faces expressing fear, which are supposed to induce a higher stress response. It therefore seems that simply interacting with nature for a short period of time is enough to positively influence the brain centre involved in stress.
Even if it is at this stage premature to conclude that this decrease in amygdala activity alone is responsible for the soothing properties of nature, these results nevertheless remain very interesting, because they show for the first time that interacting with nature has measurable positive effects on the activity of certain areas of the brain, particularly in an area involved in the stress response.