There are eight hypotheses for the occurrence of dreams, each of which is harshly criticized by scientists.
The author of the first, Sigmund Freud, believed that dreams are the latent aspirations and suppressed desires of a person.
There are ideas that dreams can be a consequence of "data systematization" or "preparation for danger" that the brain conducts to "rehearse" the encounter with a threat in a dream (a hypothesis belongs to the Finnish neurologist Antti Revonusuo).
Another hypothesis considers sleep to be a protective evolutionary mechanism, because during sleep the brain retains all types of activity, excluding motor activity, that is, a person becomes "very similar to a corpse." Thus, sleep protects a person by disguising him as a dead person.
Harvard psychology professor and sleep researcher Deirdre Barrett describes sleep as mobilizing resources to solve problems. She claims that in a dream, the human brain works much more actively and inventively.
Ernest Hartman's modern "theory of dreams" presents dreams as a therapeutic mechanism for getting rid of negative experiences. And psychiatrist Zhang Jie believes that the brain during dreams is busy processing memories. That is, sleep is the moment when images are sent for long-term storage.
As for Russian physiologists and sleep researchers, many of them are inclined to the latter hypothesis of the occurrence of dreams as a "side effect" of the brain working during sleep. It is also supported by Ivan Nikolaevich Pigarev, Doctor of Biological Sciences, Chief Researcher of the Sensor Information Processing Laboratory of the Institute for Information Transmission Problems of the Russian Academy of Sciences.
Ivan Nikolaevich Pigarev - specialist in the field of vision physiology and sleep physiology, Doctor of Biological Sciences, Chief Researcher of the Laboratory of Information Transmission in Sensory Systems of the Institute for Information Transmission Problems of the Russian Academy of Sciences. Photo: IITP RAS
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The scientist describes the scheme of the formation of dreams as follows: at the time of wakefulness, signals from exteroreceptors, a group of specialized sensitive formations that perceive external stimuli, enter the cerebral cortex for processing. From there, signals go to structures associated with the occurrence of sensations. Ivan Pigarev believes that these are structures of the basal ganglia located in the forebrain zone, located on the border between the frontal lobes and above the brain stem.
Basal ganglia. Fotolia / decade3d
The activation of neurons in this zone is associated with the appearance of sensory images in the mind. In a dream, the direction of the flow changes: signals do not come from outside, but from inside. They come from interoreceptors - a large group of sensitive nerve endings scattered in various tissues and internal organs (in the heart, blood and lymphatic vessels, respiratory organs, digestive tract). The flow of these signals determines the pattern of neural activity and EEG during sleep. In a dream, the sensory zone is blocked, since no information comes from outside, the person's consciousness is turned off. However, this block is not absolute; some signals from within get there. They affect the same neurons in the basal ganglia that were responsible for sensations during the day.
Signaling neurons during sleep and wakefulness. Illustration by RIA Novosti. A. Polyanina
Thus, some images penetrate into consciousness, which, in fact, are just noise. It especially affects the neurons that were most excited during the last period of wakefulness. If we accept this hypothesis, it turns out that dreams do not have any functional significance, but represent a mild and harmless sleep pathology.
Anna Urmantseva