We take it for granted that breathing and feelings go hand in hand: Deep breaths make us calm, and short, shallow ones signal a sense of panic. This undeniable link is what’s responsible for the success of almost every wellness intervention out there — from yoga to meditation to laughter and running — but why it’s such a powerful connection was never clear until now. By probing the neurological breathing center, scientists discovered the part of the brain that controls the intensity of breathing in the first place.
On Thursday, a team of scientists report that they’ve pinpointed a tiny ball of neurons in the brain’s “breathing center” that reaches out to the area that deals with general alertness, attention, and stress. The paper’s lead author, Kevin Yackle, Ph.D., a physiologist at University of California-San Francisco, tells Inverse that this was an unexpected discovery, despite the obvious link between breathing and yoga, meditation, and other wellness practices.
“It’s known that breathing is connected with all these things, but how — whether it was direct or indirect — wasn’t known,” he said in a phone call from Austria, where he was presenting his work at a neuroscience conference. “And so, this was surprising to us — to be able to find that there’s a specific neuron in the breathing center that’s doing this.”
Yackle was well aware of the brain’s breathing center — a knot of neurons known as the pre-Bötzinger complex (PBC) buried deep in the brainstem — but, even though that region had been discovered to be responsible for triggering breathing in 1991, nobody was sure how it controlled breathing’s rhythms. “The question that motivated all of this work was, can we identify the key cell types and molecules that generate breathing rhythm?” Yackle explains. By analyzing the genes expressed by the different types of neurons within the breathing center, he and his team pinpointed a tiny subgroup whose axons reached out to the “locus coeruleus” — the brain’s headquarters for general anxiety.
The idea, Yackle explains, is that these neurons form a bridge between the brain’s breathing center and stress center, and they’re ultimately the reason why our body’s breathing hacks — deep breaths for calmness, and short breaths for arousal — actually work.
“We think that, if you were hyperventilating, these neurons would be more active, and then they would activate this other brain center more, which would then cause more arousal. And then the opposite, if you had slow breathing, you have less activation in the center, which would lead to more calmness,” he says.
An unexpected quirk of the subset of neurons, however, reveals just how complex and sophisticated breathing really is, as National Institute of Neurological Disorders and Stroke neuroscientist Jeffrey Smith, Ph.D., who wrote a perspective to accompany Yackle’s work in Science, pointed out to Inverse. “The interesting thing is that the PBC is the inspiratory rhythm generator, but these neurons that project to the locus coeruleus don’t appear to be an essential part of the rhythm generation itself,” he says. In other words, the only function of these neurons seems to be to reach out and touch the brain’s stress center.
Yackle’s team saw this when they eliminated those cells from the mouse brain using genetic engineering: The resulting mice kept on breathing, but their breathing was oddly, unnaturally calm. Putting that part of the breathing center on mute, it seems, in turn, prevents the brain’s stress center from getting activated — hence, slow-breathing zen mice. To both Smith and Yackle, this is an indication that breathing is so much more than just breathing; it looks like the brain, over evolutionary time, developed specialized neurons for the sole purpose of integrating breathing with higher-level functions, like experiencing stress and emotions, or talking and singing.
“Think about how breathing ultimately gets integrated with other behaviors,” Smith says. “This happens automatically — laughing, crying, this all involves control of breathing. And then, cognitively, singing, and what we’re doing right now — we’re controlling breathing and interfacing it with cognition to produce sounds, speech, and communication.”
Yackle believes his team’s findings can, in addition to underscoring the link between breathing and emotion, help shed light on how to treat issues related to irregular breathing, like panic attacks. “People will begin to hyperventilate and then they’ll go into a panic attack, and so we think that if you could perhaps silence these cells, pharmacologically, we could perhaps prevent the stress or anxiety or arousal that’s caused by breathing,” he muses, referring back to his genetically modified, calmly breathing mice.
“We didn’t do a very detailed analysis of how they were after a year, but they certainly continued to live and seemed okay,” he laughs.