“The cause of the sigh we make when we are sick is in the amygdala”

Sometimes words are not needed, just look carefully. Someone receives a call, listens to it carefully, remains silent for a second and lets out a long sigh. Nothing more is needed: we know that something has happened, that there is bad news. It is a language older than words, the body screaming in its universal language.

That language, for the neuroscientific communicator Nazareth Castellanos, is inscribed in our brain. The thing is, it’s easy to misunderstand.

How the amygdala ‘hypertrophies’ (and the stories we tell about it). Castellanos has a very interesting conference that has been circulating on the internet for weeks. As the story of how the brain is “deflated,” the amygdala “deflated,” and “reset” has circulated, it has gained popularity and lost accuracy.

It is true that sighing is inscribed in our socio-emotional system, but the explanation is a little more complex.

What triggers the sigh? To answer this question we have to go to a tiny circuit within the brain stem. In 2016, the team of Li, Krasnow and Feldman mapped in mice and discovered that there are about 200 neurons that make two very specific peptides that are behind sighs.

The two peptides (neuromedin B and gastrin-releasing peptide) have a lot to do with the pre-Bötzinger complex, what some call the pacemaker of respiration. But, in general, we are talking about something very basic: if they appear, they sigh; If you block the receptors, the sighing stops.

And the amygdala? So what does the amygdala have to do with all this? The amygdala is part of the human ’emotional processor’. That’s the thing. In 2015, Dlouhy and Richerson, from the University of Iowa, found that electrically stimulate the amygdala could cause apnea and a drop in oxygen… without the patients realizing it. They didn’t notice the choking, or anything strange.

Although we don’t have the exact biological mechanism (and we don’t know if it has anything to do with sighing), it is true that the amygdala plays a role in breathing control. And that the story is plausible. In fact, Castellanos, in an interviewused the precise term: he spoke of an amygdala that ‘increases its activity’, of an ‘apnea induced by the amygdala’. It is, as I say, more than plausible.

Is a “sigh” “our body telling us we’re fed up”? That’s one way of looking at it, of course. But in reality the sigh is an element of ‘high neuroscience’ that we do not understand very well. We only know that what activates it is something that has been in our brain for a long time. That’s why it’s universal, that’s why we don’t need words.

Image | Bhautik Patel

In Xataka | Some philosophers boast of having found the “lost law” of evolution. It is much more complex