In the dream, octopuses have highlighted fast and slow phases

In the dream, octopuses have highlighted fast and slow phases
In the dream, octopuses have highlighted fast and slow phases
Anonim

Biologists in Brazil have discovered that octopuses can have two sleep phases - just like humans, mammals and birds. Thanks to this, octopuses can be used in research on the nature of sleep, scientists write in the scientific journal iScience.

“Sleep phases in octopuses are very similar to human REM and NREM sleep, despite the fact that our ancestors diverged more than 500 million years ago. This may indicate that REM sleep becomes necessary for all living things if their nervous system reaches a certain level of development , - explained Silvia Medeiros, one of the authors of the work, researcher at the Federal University of Rio Grande do Norte (Brazil).

Scientists distinguish two types of sleep in humans, which are constantly replacing each other. Immediately after falling asleep, a slow phase sets in - a state of maximum rest, in which the body recovers its strength, and the brain organizes memories.

After a while, the person switches to REM sleep. In this case, his eyes begin to move rapidly in a chaotic manner, the muscles go into working mode. At the same time, the whole body becomes numb, which prevents involuntary movements and other actions that a person often does in a state of slow wave sleep. Scientists suggest that during REM sleep, people have the most vivid dreams.

For a long time it was believed that only people saw dreams. However, recent observations show that similar sleep phases and associated forms of brain activity are characteristic of other organisms, both mammals and birds with reptiles.

Medeiros and her colleagues discovered for the first time that invertebrates could be included on this list. During the study, they observed the movement of the tentacles and the position of the eyes of octopuses of the species Octopus insularis. Scientists also tracked how the body color of the mollusks changed while they slept.

It turned out that in octopuses, two different phases of sleep could be distinguished, which are very similar to slow and REM sleep in humans. During slow sleep, the tentacles and other parts of the body of the cephalopods were relaxed, the pupils were narrowed as much as possible, and their skin did not change color (according to this indicator, scientists judge the change in the mood of the animal).

During the REM sleep phase, the eyes of the octopuses began to move in different directions, the tentacles began to contract in an arbitrary manner, and the color changed continuously. This period of activity was usually short-lived, about six minutes. After it was replaced by a new phase of slow sleep, which lasted several times longer.

"Of course, octopuses are unlikely to see any complex and long dreams, since this phase lasts only a few minutes. Figuratively speaking, their dreams are most likely similar to clips or GIFs," concluded Medeiros.

In the near future, scientists plan to trace how the pattern of brain activity changes during each of these phases. They hope that this will help to find out what dreams octopuses see and what role sleep plays in the functioning of the nervous systems of vertebrates and invertebrates.

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