Try it. Breathe slowly and smoothly. A pervasive sense of calm descends. Now breathe rapidly and frenetically. Tension mounts. Why?

It’s a question that has never been answered by science, until now.

In a new study, researchers at the Stanford University School of Medicine and their colleagues have identified a handful of nerve cells in the brainstem that connect breathing to states of mind.

A paper describing the findings was published March 31 in Science. Mark Krasnow, MD, PhD, professor of biochemistry, is the senior author. The lead author is former Stanford graduate student Kevin Yackle, MD, PhD, now a faculty fellow at the University of California-San Francisco.

Medical practitioners sometimes prescribe breathing-control exercises for people with stress disorders. Similarly, the practice of pranayama — controlling breath in order to shift one’s consciousness from an aroused or even frantic state to a more meditative one — is a core component of virtually all varieties of yoga.

“This study is intriguing because it provides a cellular and molecular understanding of how that might work,” Krasnow said.

Tiny cluster of neurons

The tiny cluster of neurons linking respiration to relaxation, attention, excitement and anxiety is located deep in the brainstem. This cluster, located in an area Krasnow calls the pacemaker for breathing, was discovered in mice by study co-author Jack Feldman, PhD, a professor of neurobiology at UCLA, who published his findings in 1991. An equivalent structure has since been identified in humans.