How Nature Changes the Brain

A recent study confirms that contact with nature is an excellent way to shake the blues away. Turns out that one of the best remedies for sadness and depression are green walks.

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Researchers proved that a walk in the park actually helps eliminate the most persistent negative thoughts, those whose result is often depression and malaise. The study from Stanford University was the first to investigate the impact of the natural environment on brain activity, and the results showed that although we are increasingly urban creatures – more than 50% of the world population now lives in cities – our brain still needs nature to be fine.

A therapeutic walk through the woods

Led by graduate student Gregory Bratman, the study revealed that even a mere walk of an hour and a half through the campus at Stanford University is able to change people’s brains for the good. Bratman and his colleagues found that the contact with nature helps to eliminate or reduce a brain process that is known in academic circles as morbid rumination.

The more colloquial term is brooding – a persistent dwelling in negative thoughts. Depressed people are known to be given to such ruminations. To those, Gregory advises that taking an hour to unwind among the woods is almost like a therapy.

Bratman studies the psychological impact of urban life. Prior studies had already shown that people living in the centers of large cities have a greater tendency to anxiety and mental illness than those who live closer to nature. We need not be scientists to know that the hustle and bustle, pollution, traffic and other urban problems cause stress and anxiety.

But we are so used to the urban lifestyle that we often neglect and forget how much we need nature to be fine. Thus, Gregory Bratman decided to conduct a more profound experiment on the subject

The study analyzed the reduction of activity in a brain area called the subgenual prefrontal cortex. That’s where the brooding thoughts are believed to form. Bratman and his team selected 38 healthy people who live in crowded cities for the project. At first, they verified the blood flow in the prefrontal cortex of the participants’ brains using tomography. They considered that the more blood, the more activities that area of the brain performs. Volunteers also answered a questionnaire to assess their level of contentment and natural inclination to brooding.

the subgenual prefrontal cortex is in red
The subgenual prefrontal cortex is in red…

The subjects were divided into two groups. The first was instructed to walk in a quiet, leafy part of the Stanford campus, while the second had to walk in the busiest part of downtown Palo Alto, California. They were not allowed to listen to music during these walks. After the 90 minute-walk was up, volunteers went through tomography again and answered more questionnaires.

It was found that those who walked through the urban center were more agitated, showing significantly more blood flow in the prefrontal cortex. Participants who strolled by wooded path, on the other hand, revealed a more positive mindset in the questionnaires and had less blood flowing in the prefrontal cortex.

Figure1_IMG_7187_cropped_mThe methodology was the most simple, but by no means ineffective. Basically measuring the brain activity of volunteers before and after a ride on the Stanford campus. And comparing it with the pattern recorded before and after a walk on a noisy and busy street. This is done with magnetic resonance imaging (MRI), a technique that has revolutionized neuroscience.

According to Bratman, various aspects of the research still need to be improved. In fact, not Bratman nor anyone else has yet discovered why we need so much contact with nature to get well and how exactly it changes our mind in a positive way. It also remains unclear how the verified results should be interpreted.

That is, whether they’re actually evidence of an intrinsic effect of natural environments on our brains, rather than just an obvious expression of the well-known negative influences of urban environments on the human psyche.

Time to go back to the roots

In any case, there’s little reason to doubt that if you are a city dweller, a walk to the nearest park can definitely help you unwind. The study impresses even those who have always argued for a close contact with nature. Much as one might have thought how important nature is, no one had imagined that the contrast between its psychological effects with those of urban environments would so great. Published on one of the most respected scientific journals in the world – Proceedings of the National Academy of Sciences (PNAS) – this study has wide repercussions.

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