Neurobiologists have revealed why old and new memories do not blend together.

Sleep plays a significant role in memory formation. Recent scientific research has shown that during rest, the brain is capable of not only analyzing past experiences but also projecting future scenarios based on new information. Additionally, researchers have discovered why some memories endure throughout a person's life and scientifically tested the saying "Morning is wiser than evening."

Experts from Cornell University in the USA examined how the brain processes information received at different times. The findings of the study were published in the scientific journal Nature.

The authors of the publication conducted an experiment involving mice. First, the rodents were trained to find hidden treats. Then, as they fell asleep, the activity of neurons in their brains was suppressed during one of the sleep stages.

While the mice sleep, their pupils constrict and dilate. This alternation corresponds to the stages of slow-wave sleep. During this time, the eyes of the sleeping mice slightly open, allowing for easy observation of the pupils. If electrodes are introduced into the brains of the rodents, as the authors of the article did, it becomes possible to simultaneously monitor neuronal activity.

The scientists affected the brain cells of the mice either during the narrow-pupil phase or the wide-pupil phase. In the first case, after waking, the rodents did not remember how to reach the treat. In the second case, they remembered recent information about where the treat was located but lost memories formed a few days prior. However, if the experimenters did not influence brain activity, all memories remained intact in the awakened mice.

The researchers concluded that the brains of the rodents processed different information at various stages of sleep to prevent the mixing of memories from different times. This way, the organism managed to ensure continuous and effective learning.