People can still learn while sleeping
Unusual experiments on sleeping volunteers helped neuroscientists to prove that people can learn new information only during a phase of «fast» sleep, according to a paper published in the journal Nature Communications.
«The question whether a sleeping person to remember new information excites the minds of scientists for decades. We were able to show that unconscious, hidden memories can be formed during sleep, but only during REM sleep and transition between quick and deep sleep. The same stimulation in the phase of deep sleep, on the contrary, leads to the opposite effects,» write Thomas Andrillon (Thomas Andrillon) from the University of Pierre and Marie Curie in Paris (France) and his colleagues.
There are two types of sleep — rapid and slow sleep, which constantly alternate with each other. When falling asleep, there comes a phase of slow sleep, during which the body gradually «turned off» and regain strength.
During REM sleep the body switches to «work mode», but all muscles «shut down» for the sake of security, and the person becomes totally immobile. This phase is characterized by rapid chaotic eye movements, it is believed that at this time people see the most vivid dreams.
Long enough, as explained by Andrillon, scientists have debated whether a person can learn new information during REM sleep, or at this time, all his senses completely «disabled» and he can’t perceive information from the outside world. Many neuroscientists believe that the perception of signals from the outside world would interfere with memory consolidation, and therefore the brain will or to actively suppress them, making «internal» memories more vivid, or simply ignore, removing information about the external stimuli.
Andrillon and his colleagues checked whether it’s actually, in a very unusual experiment in which several volunteers who agreed to spend one night in the laboratory, scientists had to find a specific sequence of sounds «hidden» in the white noise.
Usually this job for anyone, but in order to succeed, most of them need a few dozen auditions a similar record. This feature is similar to the «noise test» as it is called neuroscientists, allowed them to see if people recognize this combination sounds faster, if it is played in a dream.
Following this idea, Andrillon and his colleagues divided the volunteers into several groups, connect them to the EEG and put them in a special room, which speakers began to play a recording of «white noise» at a time when their brains are engaged in one or another phase of sleep.
As shown by these experiments, volunteers, listening to the noise these «melodies» during REM sleep, several times faster determined the sequence of sounds than they have ever done it before the start of the experiments. On the other hand, the playing of these recordings during the phase of deep sleep only worsened the memory of the volunteers and forced them to spend on the search sequence is much more time than before bed.
Similar to the results of experiments, as the researchers note, suggests that the person is not completely «disconnected» from the external world during sleep and continues to perceive and remember information. Scientists believe that further observation of the brain during sleep can help us understand how memory works and how to fix the violations in its work, including amnesia and the newly opened syndrome «Groundhog day».