During the deep sleep phase, the brain evaluates and selects memories, leaving only useful ones. In a dream, the memory of victories and awards is often reactivated.
Scientists from the University of Geneva in Switzerland were able to find out what a person thinks about while sleeping. In the experiments, the researchers used fMRI and EEG, and they also developed a decoder that can decode the brain activity in the deep phase of sleep and show what it corresponds to.
During the experiment, the scientists invited a group of volunteers to play games, in one they had to guess the faces, and in the other they had to get out of the maze, and the brain activity of the participants was scanned using MRI. The scientists then faked the results so that the brain associates the game won with positive emotions. The participants' brain activity was then examined during sleep.
Studies have shown that in deep sleep, patterns of brain activation were similar to those recorded during play. During sleep, more areas of the brain associated with the game in which the participants won were activated were activated. Scientists have determined that the memory of victories and awards is more often reactivated during sleep. The results of the work were published in the publication Nature Communications.