ITHACA, N.Y. – A groundbreaking study from Cornell University has revealed that lab mice, when rewilded into natural environments, exhibit significantly reduced anxiety levels. This research, conducted over two years, demonstrated that even a single week in the field could reverse the fear responses typically observed in these animals. The findings, published on December 15 in Current Biology, draw parallels with human psychology, suggesting that a broader range of experiences can enhance a sense of agency and alleviate anxiety.
Senior author Michael Sheehan, an associate professor of neurobiology and behavior, explained the innovative approach: “We release the mice into these very large, enclosed fields where they can run around and touch grass and dirt for the first time in their lives. It’s a new approach to understanding more about how experiences shape subsequent responses to the world, and the hope is that what we learn from these mice will have more generalizability to other animals and to ourselves as well.”
Understanding the Elevated Plus Maze
The researchers employed the elevated plus maze, a widely recognized and humane method for assessing anxiety in mice. This maze consists of two arms: one enclosed, providing a sense of safety, and the other open and elevated, where mice feel exposed. Traditionally, mice exhibit a fear response by spending less time in the open arms after initial exposure.
The Cornell team conducted trials where lab mice were exposed to the maze before rewilding half of them. The mice that remained in the lab continued to show the expected anxiety response, avoiding the open arms. However, the rewilded mice displayed a marked change in behavior upon re-exposure to the maze.
“The rewilded mice show either no fear response or a much, much weaker response,” said Matthew Zipple, first author and a Klarman Fellow.
Reversing Established Anxiety
Intriguingly, the study also found that mice with an established fear response, when rewilded, experienced a reset in their anxiety levels. “We put them in the field for a week, and they returned to their original levels of anxiety behavior,” Zipple noted. This suggests that living in a naturalistic environment can both prevent the formation of a fear response and reverse it once established.
Zipple emphasized the concept of agency as a crucial factor in this behavioral change. “What I mean by agency is the ability of an animal to change its experiences in an environment through its own behavior,” he explained. The rewilded mice, with the freedom to move, burrow, climb, and navigate their surroundings, gained confidence and a richer context for new experiences.
Implications for Broader Applications
The implications of this study extend beyond mice, offering insights into the potential benefits of diverse experiences in reducing anxiety in other animals and possibly humans. Sheehan elaborated on this point: “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. 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.”
This research opens new avenues for understanding anxiety and the impact of environmental factors on mental health. The concept of rewilding, albeit in a controlled manner, could inform therapeutic strategies aimed at reducing anxiety through exposure to varied and enriching experiences.
As the study continues to garner attention, the next steps involve exploring how these findings can be translated into practical applications for other species, including humans. The potential for rewilding or similar interventions to enhance mental well-being is a promising field of study, with the Cornell team’s work paving the way for future research.
