Neurophysiologists from Goethe University in Frankfurt in collaboration with specialists from Harvard Medical School in Boston succeeded in shedding light on the nature of lucid dreaming. They published their results in the journal Nature Neuroscience. They figured out the features of the electrical activity of the brain required for the emergence of lucid dreams. Moreover, they were even able to induce them in subjects by electrical stimulation of the brain.
Despite the fact that scientists have been actively studying sleep for a long time, the nature of dreams is not yet fully clear to them. As Vladimir Kovalzon, Doctor of Biological Sciences, most nowadays view the visual images that appear in dreams as simply a byproduct of brain activity. Nevertheless, scientists are making attempts to understand dreams, learn to read human dreams, and possibly program.
How are lucid dreams different from ordinary ones? As the authors of the article write, during ordinary dreams, the brain is in a primary state of consciousness: what is happening here and now is perceived directly, and the memory of the past and planning for the future are not available. When a person wakes up, cognitive functions of a secondary, higher order are instantly activated: a person is aware of himself in time and space, uses past experience, foresees future events, shows free will and is capable of reflection.
During lucid dreams, there are elements of secondary consciousness of a higher order, so a person behaves not as a passive, but as an active subject of what is happening. He knows that he is sleeping, that he can wake up, he can take control of what is happening in a dream, for example, drive out what something nightmare or continue an exciting adventure.
The electrical waves that the brain generates are divided into several frequency ranges - delta (0.5-3 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (14-40 Hz) and gamma (40 Hz and above).
When registering an EEG during sleep (somnogram), experts found out that lucid dreams are accompanied by synchronization of the activity of different brain regions and the appearance of very high frequency rhythms (about 40 Hz) in the gamma range in the frontal and temporal regions.
Scientists previously associated such high-frequency gamma rhythms only with the state of active wakefulness, intense intellectual activity. It was unexpected to find them in a state of sleep.
Ursula Voss and her colleagues studied 27 volunteers who, according to them, had not experienced lucid dreaming for the previous several nights. The scientists wanted to answer the question of what comes first: gamma activity leads to lucid dreams, or vice versa. They stimulated the brains of the subjects during sleep with a weak electric current of different frequencies (from 2 to 100 Hz), that is, in all frequency ranges in which the brain itself works. The electrodes were applied to the frontal and temporal regions. According to the researchers, this method of stimulation was not felt at all by the volunteers and did not interfere with their sleep.
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It turned out that stimulation at a frequency of 40 Hz does not disrupt the usual signs of REM sleep, but leads to the fact that the brain itself begins to generate high-frequency gamma waves (37–43 Hz). Scientists believe that under such conditions, neurons begin to synchronously emit electrical impulses with a given frequency. To a lesser extent, this was caused by stimulation with a frequency of 25 Hz. Stimulation at lower and higher frequencies did not affect the brain's own activity at all.
A few seconds after the end of the current, the subjects were awakened and asked about their dreams. It turned out that stimulation at frequencies of 40 and 25 Hz caused lucid dreams in the volunteers, which they could control.
Thus, scientists have found a key electrophysiological sign of lucid dreams and have learned how to induce them artificially. In addition to the fact that this opens up the possibility of external interference in dreams, which is interesting in itself, there are also clinical applications.
Giving a person the ability to control dreams, you can save him from nightmares and obsessions. So, perhaps, the method of electrical stimulation during sleep will find application in the clinic.
Oksana Volgina
