Why do people sleep? There has long been a speculation that sleep can help people consolidate memories. Now, we finally observe for the first time how the brain stores memories during sleep.
The researchers recruited a group of volunteers and taught them to practice playing a song. After they learned to memorize, each put on an EEG electrode cap (used to monitor the electrical activity of their brains), and then lay flat and entered the fMRI. scanner. Scanners are used to detect which areas of the brain are active.
When the volunteers were asked to imagine playing the song just now in their brains, the research team observed a specific neural activity pattern (such as a special-shaped electric pulse) from the signals collected by the EEG. Once they were asked to stop imagining, this pattern did not disappear, and it was still repeating, as if everyone was practicing what they had learned subconsciously.
The volunteers were then asked to go to sleep, while the research team continued to monitor them. At first, the neural activity pattern of playing piano continued to reappear in the peripheral areas of the brain. This peripheral area is called the cerebral cortex, and it is involved in many of our higher-level conscious activities.
However, when volunteers enter non-rapid eye movement sleep (at this stage, we will have some relatively ordinary dreams), that neural activity pattern begins to disappear from the cerebral cortex, but then, deep in the brain, a “basal nucleus” “The brain area reappeared. This shows that the memory has been transferred to deeper brain areas. This is consistent with the hypothesis that the cerebral cortex must free up space in order to continue to learn new information.
Non-rapid eye movement sleep occurs a few hours before falling asleep. It can be seen that the first few hours of sleep are very important for us to consolidate our memory.
