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Heart stopping information: exactly how we faint

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

More fainting follow-up! Fainting has become a surprisingly regular sub-topic in my work in the last year because I have been studying all things vagal, because of pain-treating claims related to vagal stimulation by massage, electricity, and breathing.

Biology nerds have never quite known how spontaneous fainting actually works, just that it has something to do with the vagus nerve and tinkering with blood pressure (hence “vasvagal syncope”). Well, now we know exactly, based on a new study that nailed down the activity of specific neurons that are part of the giant vagus.

“When the NPY2R VSNs were activated, mice that had been moving around freely fainted in a few seconds.”

Those specialized vagus neurons link up to receptors in the heart that, when stimulated, actually stop the heart, painlessly. That quickly deprives the brain of the oxygen, and lights out!

Hell of a thing for the vagus to be able to do. Now to figure out what tickles the NPY2R VSNs in the first place…

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