Take a deep breath, and now breathe out slowly. From yoga to stress relief, this is a well-worn trick to help calm you down, simply because most of the time it genuinely works. Now, science may have finally figured out why.
It turns out that there is a small patch of neurons in your brain that keeps tabs on how you’re breathing, and then relays this data to another part of the brain responsible for your state of mind. Researchers found that if these neurons were killed in mice, the rodents became far more relaxed and had a reduced sense of alertness.
Research in the 90s had already found a region of around 3,000 neurons buried in the brain stem that seemed to link breathing with one's state of mind, dubbed the “breathing pacemaker”. But how it actually worked was still little understood.
To try and pin this down, the team of the latest study published in Science decided to see what genes seem to be preferentially active in this region. They homed in on 175 neurons in the breathing pacemaker and, to see what they did, they inactivated these neurons in mice.
At first nothing happened, and the team thought they had failed. But then they started to notice something. “There was a change in these animals,” co-author Mark Krasnow told NPR. "They had become chill. Mellow fellows.”
Rather than sniffing around and exploring their cage, the mice were relaxing and grooming. There was a shift in their breathing too, as it became slow and controlled.
In fact, they noted similarities between the behavior of these mice and people who have lost function in the arousal part of their brain that induces alertness and panic. This made them wonder whether or not the 175 nerves acted as a go-between for the breathing pacemaker and the part of the brain responsible for state of mind.
They think that without the neurons, the arousal center doesn't get data from the breathing pacemaker, and so the brain does not become alert. This means the breathing stayed slow because the breathing pacemaker was getting no panic signals from the arousal center. The team have dubbed these 175 nuerons "pranayama neurons" after the practice of regulating one's breath.
Althoguh more work is needed, it's possible this physical link between breathing and state of mind is critical in stress and emotion. Yoga and meditation have relied on this notion for thousands of years, and now researchers want to see if what is true for mice is also true for us.