A few months ago I wrote about the virtues of 5 deep breaths (Reset with 5 Deep Breaths, 5 Mar 2017). Now I’m back with scientific news that shows breathing affects brain function in mice. To put it briefly, there are special brain cells that connect breathing with states of arousal: sleep-wakefulness, vigilance, and emotions.

“Breathing control center neurons that promote arousal in mice” (Yackle et al., Science, 31 Mar 2017, p. 1411) summarizes its findings as follows:

Slow, controlled breathing has been used for centuries to promote mental calming, and it is used clinically to suppress excessive arousal such as panic attacks. However, the physiological and neural basis of the relationship between breathing and higher-order brain activity is unknown. We found a neuronal subpopulation in the mouse preBötzinger complex (preBötC), the primary breathing rhythm generator, which regulates the balance between calm and arousal behaviors. Conditional, bilateral genetic ablation of the ~175 Cdh9/Dbx1 double-positive preBötC neurons in adult mice left breathing intact but increased calm behaviors and decreased time in aroused states. These neurons project to, synapse on, and positively regulate noradrenergic neurons in the locus coeruleus, a brain center implicated in attention, arousal, and panic that projects throughout the brain.

In simpler words and pictures (“Breathing to inspire and arouse”, S. Sheikhbahaei, J.C. Smith, Science, same issue, p. 1370) the research focused on two regions in the mouse brain:

• preBötC – a group of neurons that had been previously identified as generating the “inspiratory rhythm” of mouse breathing, i.e., the rhythm of the in-breath. This group of cells collects inputs from many brain regions, and then broadcasts signals to many other brain regions in return.
• locus coeruleus (LC) – another group of neurons that had been previously linked to arousal (sleep-wakefulness state, vigilance, and emotions). Like the preBötC region, the LC region also collects inputs from many brain regions, and broadcasts signals throughout the brain and spinal cord.

Yackle et al. found that inside the preBötC region was a special group of about 175 neurons with special chemical characteristics (unlike their neighbors, these cells produced two special proteins, Cdh9 and Dbx1), and these special neurons were directly connected to neurons in the LC. Moreover, when Yackle et al. employed genetic engineering tools to breed mice that were missing the special set of 175 neurons, they observed that the modified mice breathed normally (the rest of the preBötC could still stimulate an in-breath), but they remained calm for longer periods than normal mice. For these mice taking an in-breath could no longer stimulate arousal.

Or, more simply, how you breathe is connected to how you feel.