Dormant neurons engage with old and new memory at different times.
Short-term memory, to one degree or another, turns into long-term memory, and sleep plays a big role in this. In a dream, the brain literally repeats what it did while awake: if you insert electrodes into the brain, you can see how in a dream the same neurons that, while awake, participated in solving some problem, demonstrate the same activity . For quite a long time, such experiments were carried out with animals, but two years ago, a neural repetition of what had been done could be seen in sleeping people.
However, even the latest information that the brain works with is still somehow different in time: we saw something today, something yesterday, something the day before yesterday, etc. Not all of it ends up in the long-term the first time. memory. At the same time, our memories of today do not erase those of yesterday. That is, the brain has a way of working with earlier and later fresh information so that they do not conflict with each other. How this happens is written in Nature Cornell University staff. They experimented with mice: in sleeping mice, the pupil alternately dilates and contracts, which corresponds to the stages of slow-wave sleep. As is known, in animals (and not only) sleep is divided into two large phases, fast and slow, but these phases themselves are heterogeneous, they have repeating stages and substages. The dilation and constriction of the pupils in mice corresponds to a repeating microcycle of slow-wave sleep that lasts only one minute. In mice, the eyes open slightly, so that it is relatively easy to observe what is happening to the pupil; If you introduce electrodes into the mouse brain, you can simultaneously influence the activity of neurons.
The mice were taught to look for a hidden treat, and then, when the mice fell asleep, the activity of the neurons in the memory center was suppressed, either in the wide pupil stage or in the constricted pupil stage. If nothing was done to the mice in their sleep, then when they woke up, they remembered how to get to the treat. If the activity of neurons was suppressed during the constricted pupil stage, the awakened mice did not remember anything. If the activity of neurons was suppressed during the dilated pupil stage, then very recent memories remained intact, but those that were formed several days ago disappeared. That is, the brain works with different information at different times, without allowing memories from different times to mix and interfere with each other.
As usual, many new questions arise here – for example, is there an even more detailed difference in time between different information in a dream; could it be that the memory of the day before yesterday is better processed than yesterday’s; are there similar microstructural elements in human sleep, etc. Last year we talked about a study in which a rather complex structure of signals was discovered in sleeping neurons; It may well be that in a dream there are some other microstructures that are important for the general cognitive state. In general, although a lot of work is devoted to memory transformations, this topic continues to surprise and will continue to surprise for a long time – for example, at the very end of last year we learned that long-term memory can appear in addition to short-term memory – at least in mice.
Source: www.nkj.ru
