It has been known for nearly 20 years that slow, synchronous electrical waves in the brain during sleep support the formation of memories, but why this happens has not been understood.
An explanation was found by a team of researchers from the Berlin clinical complex Charité (Germany). The press service of the establishment reports this.
According to the study, slow waves make the neocortex, the location of long-term memory, particularly receptive to information.
Experts believe that while we sleep, our brains replay the events of the day, moving information from the seat of short-term memory, the hippocampus, to long-term memory, located in the neocortex.
Of particular importance in this process are slow waves – slow synchronous fluctuations in electrical voltage in the cerebral cortex that occur during the hibernation phase. They can be measured using an electroencephalogram (EEG), the article states. “Waves occur when electrical voltage in many neurons increases and decreases simultaneously once per second.
Until now, it was not known what happens inside the brain during this process, since studying the flow of information inside the human brain is very difficult. To establish this, scientists:
- They used intact human brain tissue, which is extremely rare. Tissue samples were collected from 45 patients undergoing neurosurgery to treat epilepsy or a brain tumor at multiple institutions;
- simulated the voltage fluctuations characteristic of slow brain waves during hibernation in tissue, and then measured the response of nerve cells. To do this, they used glass micropipettes positioned with nanometer precision;
- To “listen” to communications between multiple nerve cells connected through tissue, scientists used up to ten “pipette probes” at a time—a very large amount of this technique, known as the multipatch technique.
As a result, the team found that synaptic connections between neurons in the neocortex are maximally strengthened at a very specific point in time during voltage fluctuations:
- synapses work most efficiently immediately after voltage rises from low to high. During this short period of time, the cerebral cortex should be considered to be on high alert;
- If the brain reproduces the impression specifically at this time, it is transferred to long-term memory especially well.
Therefore, slow-wave sleep appears to support memory formation by making the neocortex particularly receptive over many short periods of time, the researchers note.
According to scientists, this discovery could be used to develop methods to improve memory, for example, for mild cognitive impairment in older people.
An unusual way to quickly fall asleep was proposed by scientists from South Korea.
Source: Racurs
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