It is one thing - remember new information, such as a telephone number or a foreign word, and quite another - to put this information into the part of the brain, where it can be easily removed at the right time.
A new study published in the journal Journal of Neuroscience, researchers from Harvard Medical School and the University of York, confirmed that sleep helps to cope with both tasks.
Scientists have found that sleep not only allows you to store just learned the word, but also helps to put it in a department of the active vocabulary.
This work was funded by the Council for Economic and Social Research. It was the fact that scientists are trained volunteers new words in the evening, and right after that we tested. Then, the volunteers slept in the laboratory while their brain activity was recorded using an electroencephalogram (EEG). Testing the next morning revealed that they could remember more words than immediately after the study, as well as recognize them faster demonstrating that sleep helped consolidate the new information in memory.
The control group showed no such results, after the members of the group were taught the words in the morning and repeated testing in the evening, with no sleep in between. EEG monitoring of sleeping volunteers showed that during the deep sleep phase, new memories were fixed in memory. In this case, during REM sleep the process was not observed.
When the researchers checked whether the new words become part of the existing knowledge and active vocabulary, they found the inclusion of different types of activity in the sleeping brain. "Sleep spindles" EEG - a brief but intense flash of cerebral activity, which reflects the exchange of information between the memory in the brain keepers - hippocampus, lies deep in the brain neocortex and disposed on the surface of the brain.
The memory in the hippocampus are stored separately from other memories, while the information in the neocortex is connected to other knowledge. Volunteers, EEG which showed more sleep spindles during sleep, better than any other place could have just learned words in the area of the active vocabulary. New words are copied from the hippocampus to the neocortex during sleep.
Co-author of the study, Professor Gareth Gaskell Department of Psychology University of York, said: "We knew from our previous work that sleep plays a role in the reorganization of new memories, but the first time we were able to directly observe the process and to understand the role played by the sleepy here spindle. "
These results indicate the importance of sleep and related processes in the brain to increase vocabulary. But the same principles, most likely apply to other types of training.
The lead author, Dr. Jacchia Tamminen said: "The new knowledge can be useful only if you combine them with the information that you knew before. Imagine a game of chess, where the modified rule that runs one of the figures. You be able to apply the amended rule only if modify the strategy and tactics of the game. Our research has identified brain activity that reflects the processes that organize new memories and combining it with existing knowledge. "