Take a deep breath

30 March 2017

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Take a deep breath... hold it... and let go... You should be feeling better after that - science says so!

Yoga practitioners preach the power of breath control; meditators know it works, and people with panic attacks are told to reduce their breathing rate to reverse their anxiety symptoms. Now a new study reveals why, and shows that the part of the nervous system that controls our breathing rate also sets the tempo of your arousal and mood.

The drive to breathe originates in a structure called the preBotzinger complex. This is a cluster of a few thousand nerve cells sitting in the brain's medulla, which acts as the neurological interface linking the spinal cord with the forebrain. These nerve cells are organised into "pattern generators" that fire off rhythmic barrages of impulses that drive respiration. Superimposed on this are signals, like exercise or the detection of low blood oxygen, which make you up your breathing rate when you need to. 

But working with experimental mice, Stanford scientist Kevin Yackle and his colleagues, writing in the journal Science, have shown that the nerve cells in the preBotzinger complex are not all made equally. A small number, perhaps just 200, display quite different characeristics and seem to play a key role in tethering your mood to your breathing rate. 

The Stanford team made this discovery by using a toxin to selectively remove a sub-population of the preBotzinger complex cells, expecting this to result in inviable mice incapable of breathing. But, to their surprise, the animals appeared to be healthy and normal.

A closer inspection, however, showed that their breathing pattern had changed significantly. The toxin-exposed mice took more slow breaths. The also spent less time actively exploring their environments, devoted threefold more time to grooming and twice the time to sitting calmly. Measurements of their brain activity also showed a corresponding increase in theta waves, which are associated with a state of relaxation. When they needed to, however, the animals could still breathe rapidly, it was just that their arousal "set point" appeared to be much lower.

To understand why the removal of a small number of nerve cells should make such a profound difference, the researchers followed the connections normally made by the population of cells they had removed.

These cells, they found, use a nearby relay station in the brainstem, called the locus coeruleus, to send alerting signals to other parts of the brain. These cells, the researchers speculate, couple mood and arousal to breathing, perhaps as part of an anticipatory reflex. They pick up on the activity of the surrounding pattern generators and, when breathing quickens in response to demands placed on the body, they bring other regions of the nervous system into line.

So your Yoga instructor is absolutely right to emphasise the importance of breathing. And for a person hyperventilating during a panic attack, the best thing to do is to realise that rapid panting is probably making the problem happen in the first place...  

respiratory-brain-circuit-mouse.JPG

The diagram depicts the pathway (in green) that directly connects the brain's breathing center to the arousal center and the rest of the brain.

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Thank you for your quick reply. You did not, though, actually comment.....Sue

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