Brain drowned out the perception of meaningful speech in the dream

French scientists have found that during REM sleep the brain as during wakefulness, better processes meaningful speech, not nonsense. The processing itself is still less efficient, which means that the brain does not block inbound during sleep information, and filters it. During active eye movements in this phase virtually no speech processing is not happening. As eye movements in a fast phase correlates with the appearance of dreams, such a restriction mechanism may explain why external information is rarely included in dreams, write scientists in Current Biology.

The brain is active even when a person sleeps, but the greatest activity characteristic of REM sleep. Despite the increased activity, the brain in this phase is still possible to limit the impact of external stimuli, and this is done quite efficiently: otherwise, sleep would, on the one hand, all the time I woke up, and with another — would not see any dreams (and most of them actually related to REM sleep).

While it is clear that fully constrain the incoming information, the brain cannot and, most likely, filters it, otherwise people would not have even woken up from loud sounds. To understand how this happens, scientists have decided under the guidance of Sid Kouider (Sid Kouider) of the superior normal school in Paris. The participants of his experiment (there were 18), scientists were allowed to listen to the recording of normal speech and nonsense — artificial phrases, consisting of phonetically correct language pseudostem and observe the rules of grammar (a well-known example of such a phrase — a sentence about gokuu kusdra or the first stanza of “Jabberwocky” by Lewis Carroll).

First, the participants listened to those and other phrases individually, and the activity of their brains was recorded using EEG. The resulting activity was correlated with the curve of the change in the audio frequency reproduced speech to the participants so that then the curve of EEG, it was possible to identify and reconstruct the speech.

Then, the researchers used classic experimental paradigm to test the “cocktail party effect” — ability to focus on one stimulus, filtering all the rest: the participants consisted of meaningful speech in one ear and no sense in another, and asked to focus only on meaningful text. Then the scientists repeated the experiment when the participants were asleep. In fact, and in another case the activity of the brain recorded with EEG, and then reconstructed from her speech and not making sense in isolation — on the basis of data obtained before.

The analysis showed that the signal of the EEG during wakefulness and during sleep, can be identified and discussed, and nonsense, and it stands out better: and direct instruction to focus on it while awake and during sleep. Preference meaningful speech was also observed during and fast and slow phases of sleep. It is also interesting that nonsense during sleep, was able to reconstruct about the same way as during wakefulness (unlike speech, which if wakefulness to reconstruct much better): this indicates that the brain during sleep in fact is not blocking incoming information and filters it, reducing the perception of the information, which may disturb sleep — that is, meaningful speech.

Leave a Reply

Your email address will not be published.