Home' Trinidad and Tobago Guardian : April 6th 2017 Contents B34 body & soul
guardian.co.tt Thursday, April 6, 2017
Take a deep breath in through your nose, and
slowly let it out through your mouth. Do you
Controlled breathing like this can combat anxiety,
panic attacks and depression. It's one reason so many
people experience tranquility after meditation or a
pranayama yoga class. How exactly the brain associ-
ates slow breathing with calmness and quick breathing
with nervousness, though, has been a mystery. Now,
researchers say they've found the link, at least in mice.
The key is a smattering of about 175 neurons in a part
of the brain the researchers call the breathing pace-
maker, which is a cluster of nearly 3,000 neurons that
sit in the brainstem and control autonomic breathing.
Through their research is in mice, the researchers
found that those 175 neurons are the communication
highway between the breathing pacemaker and the
part of the brain responsible for attention, arousal and
panic. So breathing rate could directly affect feeling
calm or anxious, and vice versa.
If that mouse pathway works the same way in hu-
mans, it would explain why we get so chilled out after
slowing down our breathing.
To figure this out, researchers first divvied up the
3,000 neurons in the breathing pacemaker by their
genetics, as neurons with similar genes might have
similar roles in the brain. That's how they zeroed in
on that 175.
The next challenge was to uncover their function.
Sometimes the best way to see what something does is
to see what happens when it's gone, so the researchers
inactivated those neurons.
To do so, they first genetically engineered mice
to have receptors to a toxin only on the neurons of
interest. That let them kill off only those neurons
by injecting the mice with the toxin, which is made
by bacteria called diphtheria.
Diphtheria can cause serious respiratory illness in
humans, but doesn't normally affect mice. In the en-
gineered mice, though, the toxin could kill the cells it
attached to: the 175 neurons. That way, those neurons
were knocked out and the rest were left intact and
fully functional, as the researchers explain in their
study, published recently in Science.
Finally, researchers looked at how the loss of those
neurons affected the breathing and behavior of the
mice by putting them in a pressurised chamber that's
sensitive enough to measure the size and frequency
of even the tiniest mouse breath.
"We expected that [inactivating the neurons] might
completely eliminate or dramatically alter the breath-
ing pattern of the mice," like making them gasp or
cough, says Mark Krasnow, a professor of biochem-
istry at Stanford University School of Medicine and
an author on the study. But there wasn't a change in
the breathing pattern. For a few days, the researchers
thought they had made a mistake in their experiment
and failed altogether.
After retesting the mice in the chamber under var-
ious conditions---during sleep, with elevated carbon
dioxide levels and more---Krasnow finally realised that
"there was a change in these animals," he says. "They
had become chill. Mellow fellows."
Before losing the 175 neurons, the mice did in the
chamber "what mice love to do," Krasnow says: ex-
plore and sniff. After the neurons were gone, the mice
spent much more time engaging in classic calm mouse
behavior, including relaxing and grooming them-
selves. Upon closer examination, they also breathed
That chill behaviour reminded Kevin Yackle, lead
author on the study and Sandler Fellow at the Univer-
sity of California San Francisco, of animals---humans
included---who had lost function in the arousal centre
of the brain that induces alertness and panic. They
too were mellow fellows, giving Yackle the idea that
the arousal centres in the brains of his mice weren't
getting any input from the breathing centres, so they
didn't act alert.
At the same time, those breathing centres weren't
getting any panic or alert messages from the arousal
centre, so their breathing stayed slow. The connection
between the two brain areas, the 175 neurons, had
And that connection is key, Krasnow says. Krasnow
and Yackle think that if this mouse pathway also exists
in humans, it could be useful in treating people with
anxiety, where the pathway may be overactivated.
Controlled breathing or medication could help lower
activity in the pathway, he speculates, by lowering
feelings of panic and the rate of breath. (NPR)
Controlled breathing like this
can combat anxiety, panic
attacks and depression.
Mouse brains may explain
how breathing calms the mind
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