Our brain activity during sleep can indicate when we are dreaming

By Tanya Lewis, the article is published with the approval of Scientific American Israel and the Ort Israel Network 17.09.2017

"To sleep, perhaps to dream" - Shakespeare may not have meant exactly our nocturnal journeys to other worlds, but that does not detract from the mystery or the importance of dreams.

Sleep gives science a way to examine consciousness in all its various forms, from vivid dreams to complete unconsciousness, says the neuroscientist Benjamin Baird. When a subject is asleep, researchers can isolate the experience of awareness from the interfering influence of the senses.

In a recent attempt to peer into the old brain, Baird and the important awareness expert used Giulio Tononi, both of the University of Wisconsin at Madison, and their colleagues in scalp electrodes to record brain waves from sleeping subjects in high-density electroencephalography. They woke the subjects frequently and asked them if they had dreamed, and if so, what. In one experiment out of all the experiments, they collected about 200 such reports from 32 subjects, and in another experiment they added another 800 reports from a smaller group of subjects who were specially trained in reporting dreams.

The team of researchers identified a "hot zone" in the back of the Cortex, near the back wall of the skull. In this area, low-frequency brain waves (associated with unconsciousness) decreased, while high-frequency wave activity increased near the report of dreaming - whether or not it was accompanied by rapid eye movements (REM). (Contrary to popular belief, dreaming can occur both during REM and non-REM.) The findings were described in Nature Neuroscience.

In a third experiment, done on seven subjects, the scientists predicted with 87% accuracy whether the subject was dreaming or not. Moreover, a connection was found between brain wave activity in certain areas and between certain dream contents such as places, faces and speech. These are areas that are activated even while awake. "We weren't really trying to predict [dream] content in this study," Baird says. But it would be an interesting "possible direction".

This approach demonstrates "a very innovative and cool model," says neuroscientist Christoph Koch of the Allen Institute for Neuroscience in Seattle, who was not involved in the research and is a member of Scientific American's advisory board. According to him, the discovery that activity related to dreaming is concentrated in the back of the brain is surprising. Because the accepted explanation is that awareness is woven in frontal-parietal areas. One of the limitations of the study is the time that passes between the subject's awakening and his report of the dream. In the end, says Koch, "we want to get as close as possible to the experience itself."

More of the topic in Hayadan:

• And in a dream I saw
• The Dreaming Mind - Part I / Part II'