Researchers from Cornell University released 44 laboratory mice into a large outdoor enclosure, allowing them to roam freely. But what happened next stunned the researchers, as after just one week, the anxiety levels of the mice returned to normal. The study's findings would help in understanding anxiety in humans, suggesting that a lack of diverse experiences may contribute to anxiety disorders.
"We put them in the field for a week, and they returned to their original levels of anxiety behavior," biologist Matthew Zipple said as quoted by Science Alert.
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"Living in this naturalistic environment both blocks the formation of the initial fear response, and it can reset a fear response that's already been developed in these animals in the lab."
The study, which was recently published in Current Biology, mentioned that the mice were placed in an elevated plus maze (EPM), a standard tool for measuring anxiety in mice. It has two arms - an enclosed arm and an exposed arm. The enclosed arm makes the animals feel safer, meanwhile, in the exposed arm, the mice are in a more open environment.
It is often seen that the mice exhibit fear when exposed to the open arms of the maze, avoiding them and preferring the enclosed spaces.
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However, the mice who were allowed to roam freely explored both open and closed spaces equally, as if encountering the maze for the first time.
The study found that the mice's anxiety levels decreased significantly after experiencing the natural environment and the process reset the mice's fear response, allowing them to overcome previously learned anxieties.
"If you experience lots of different things that happen to you every day, you have a better way to calibrate whether or not something is scary or threatening," Michael Sheehan, who is the neurobiologist, said as quoted.
"But if you've only had five experiences, you come across your sixth experience, and it's quite different from everything you've done before, that's going to invoke anxiety."
The study suggests that environmental factors play a significant role in shaping anxiety, potentially more so than biological factors.
"This opens a lot of possibilities for asking interesting questions about how our library of experiences shapes our response to novel experiences, because I think that's essentially what anxiety is - when you have an inappropriate response to something that isn't actually scary," said Sheehan.
