March 21, 2023
Another Mystery of Sleep Deciphered - 11/14/2022 - Susana Herculano Huzel

Another Mystery of Sleep Deciphered – 11/14/2022 – Susana Herculano Huzel

More than twenty-four thousand neuroscientists from several countries are attending this week’s annual meeting in the USA, sharing notes, and returning to their labs full of new information and ideas.

Unusually I stayed home because my parents were attending my fiftieth birthday, even though the US consulate canceled my plans by denying my mother’s visa—proof that in this country getting a green card doesn’t welcome family, but that’s another story. I’ve also traveled enough this year, so while my colleagues are exchanging posters in person, I’m reviewing the literature.

In a pile of promising subjects I found an article in the August issue of Science that solves a 70-year-old mystery: Where does REM come from during sleep? dreams🇧🇷 Is it random or does it correspond to eye and head movements in the dream?

Yota Sensai and Massimo Scanziani of the University of California, San Francisco, respond. The two took advantage of the fact that, with electrodes implanted in the rats’ brains, it was possible to record the activity of neurons in the thalamus that represent the current orientation of the head in the horizontal plane, at the same time that eye movements were being monitored, all in real time.

While the animal is awake and exploring the environment, the eye and head movements are completely identical: the second immediately follows the first – just as in Daniel Filho’s advice to Regina Duarte, where I taught her to raise her eyes before raising her head in front of the camera (obviously the trick impressed me, I was a girl and I remember !).

Logic: The eyes automatically move toward what they see moving; The head follows – and a very elegant reflex involving the labyrinth in the inner ear moves the eyes to the center of the orbit when the new target is encountered head-on.

And when the animal falls asleep and begins to dream … Sensai and Skenziani discovered that the eye movements, which continue to occur, precisely precede a new hypothetical head orientation, which is indicated by the thalamus.

The simplest explanation for this phenomenon is that dream content – images, sounds, touches, as well as the inner planes represented by the brain – cause eye movements that almost “move” the dreamer’s head.

But while you’re dreaming, your head and the rest of your body, paralyzed, don’t really move, so it won’t be that reflection from the maze that brings your gaze back to center. No problem: perhaps due to the hypothetical movement of the head itself, caused and represented by the brain, the eyes soon move in the opposite direction in the same way.

What the mice dreamed of, we still do not know. But the new finding struck me as a very strong indication that eyes do indeed move while we are mentally realizing our dreams. dreams.

Nations. Another reason to sleep with my blindfold…

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