Now we know why our eyes move when we dream

This was discovered by an American research team during a study on how the brain processes sensory information during wakefulness and sleep.

It probably happened that more than one person noticed that the eyes of a sleeper move rapidly under the eyelids. Why does this happen? And above all, what does this movement of the eyes reveal? Is it just the result of random shifts or does it indicate where we are looking in the dream scenario?

Since the discovery in the early 1950s of the REM phase (rapid eye movement) which, as its name suggests, is a phase of sleep in which eye movements occur, the meaning of these rapid jerks of our eye muscles has intrigued and fascinated dozens of scientists, psychologists and philosophers, but until present their significance has remained a mystery due to the technical challenges posed by their measurement. An American research team, led by Massimo Scanziani from the University of California at San Francisco, however wanted to see clearly, by measuring the electrical activity of nerve cells in the thalamus, a structure of the brain where these cells are responsible for the movements of the head. and the application of this measurement to mouse models, through which it was possible to reveal what rapid eye movements actually mean during REM sleep.

‘Cause eyes move while we dream

As noted, REM sleep is the phase of sleep when our eyes move under closed eyelids. But it is also the stage where we have vivid dreams. According to the researchers, these eye movements reflect the direction of our gaze in the dream world.

” To test this hypothesis, we measured the rapid eye movements, or saccades, that occur in mice when they are awake, and we mapped the electrical activity of their brains. – explained the scholars -. We then monitored the eye movements of sleeping mice during REM sleep with miniature cameras positioned in front of both eyes. And because mice often don’t fully close their eyelids during sleep, this allowed us to accurately measure the direction of their eye movements. And as we did when the mice were awake, we recorded their brain electrical activity to decode the changes during REM sleep.“.

As detailed in the study published by the team in the journal Science, the direction of eye movements in sleeping mice corresponded exactly to changes in brain activity, just as they do during wakefulness. ” This indicates that eye movements during REM sleep can reveal shifts in gaze in the virtual dream world, providing a window into the cognitive processes occurring in the dream brain.Added scholars.

The study also shows that during REM sleep, the part of the brain that controls head direction coordinates with the part that controls eye movement. This finding may be just the tip of the iceberg as to how separate parts of the brain work together during sleep, suggesting that if other cerebral brains also work together during REM sleep, such as those responsible for sensory perception, emotion and sense of space. , this overall coordination can be the basis for vivid and realistic dream experiences.

The researchers’ next goals will be to understand what drives changes in brain electrical activity during REM sleep, how these changes affect eye movements, and how the different senses work together for a holistic and realistic dream experience.