Friday , August 19 2022

The brain creates lifelong neurons, but the "refill" depends on the age and health of the person t



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The human body produces new cells constantly and removes old ones. But is there so much “turnover” in the brain as adults and the elderly? This question has long been a topic of scientific debate.

For a long time, scientists believed that neurogenesis (the process of creating new brain cells) stopped in a person during puberty, when the brain ceased to develop. This version was supported by work published in March 2018. Its authors found that the hippocampus (the area responsible for learning, memory and emotion formation) are not adults creating new cells.

However, literally a month later, another group of neuroscientists published a study showing that around the same number of new cells, not yet full, are included in "young" brain tissues and "elderly". . And these "newborn" neurons were found exactly in the hippocampus.

Experts have suggested that the results of such studies can depend on an important condition – the state of health of people whose brain tissue becomes an object of study. In addition, as samples are collected after death in most times of such type, the important role played by processing methods, as well as shelf life.

Neuroscientists from the University of Madrid conducted another study considering these tones. They wanted to understand the “age limits” of neurogenesis and whether it happens in the brain people with one of the most common neurodegenerative disorders – Alzheimer's disease.

The authors studied two groups of samples. The first included the tissue of the 13 patients who died between 43 and 87 years of age. All of these people were neurologically healthy and their death was due to stroke, cancer, sepsis and other disorders.

The other group consisted of brain tissue from 45 patients with Alzheimer's disease, who died between 52 and 97 years of age.

It is worth explaining that a protein of the name doublecortin (DCX) is a protein of immature neurons. Special fluorescent antibodies help to find it.

However, every brain tissue remaining after the death of patients to study is treated with paradoxaldehyde. And it can distort research results.

Specifically, the number of cells that tested positive for DCX fell sharply within 48 hours after treating tissue with the paraformaldehyde, explaining Maria Llorens-Martin, head of the t research team.

So her team worked with samples that did not spend more than 24 hours in a paraformaldehyde bath.

Studying the samples from the first group, the experts found tens of thousands of cells containing doublecortin in the dental gurus. We explain that this part of the hippocampus regulates the function of memory.

According to scientists, they observed under the true microscope young neurons: smooth and rounded, with simple branches, not yet developed. In addition, to complement the results, as well as DCX, experts have been looking for other protein markers, noting the development of new neurons.

As a result, the youngest patient of the first sample (recalling that he was 43 at the time of his death), found that approximately 42,000 immature neurons per square millimeter of tissue had been found. .

The study of other samples showed that neurogenesis lasted until death even the older people were almost 90 years old. True, the number of new neurons was lower by about 30%.

"I think we continue to produce new neurons until we need to learn new things. And this happens every second of our lives," Lorens-Martin said in an interview with the r t BBC.

When scientists began to study the tissues and brains of people with Alzheimer's, they observed a slightly different picture. These patients also showed signs of neurogenesis. However, “neonatal” brain cells were 30% less than in people of the same age without neurological disorders. That is, the disease factor was added to the old age factor: the more it went on, the worst was the ability of the brain to create new neurons.

Neuroscientists have made another important conclusion. Some people from the second group had Alzheimer's disease at an early stage, they have not yet started collecting poisonous beta-amyloid protein clusters (this is the main mark of the disease). However, there is already disruption to the formation of new neurons: immature cells were the same as 30% less than participants of the same age from the first group.

The authors of the work believe that if we understand why there is already disruption of the formation of new brain cells at the birth stage of disease, this can help create new methods of treating disorder or at least ways to slow its development. But first of all, it is important to find out whether a neurgenesis defect leads to the development of Alzheimer's disease or the opposite.

In addition, a deeper understanding of neurogenesis and the causes of its disorders can be useful for developing new strategies for renewing the brain.

According to experts, the most clear picture of neurogenesis can be obtained through direct observation of this process in the brain of living people. That's what the scientists intend to do in the next phase of the work.

Note, it will not be easy to operate a scheme of such type, as the same dentist dentist, for example, has hidden deep inside the brain. But if neurobiologists still succeed in creating new unobtrusive methods for detecting "neonatal" neurons in the living brain, this new word will be the early diagnosis of Alzheimer's disease and, possibly, other neurodegenerative disorders.

A scientific article on the results of the work of Spanish scientists published in the journal Nature Medicine.

By the way, earlier, researchers found that regular exercise activates neurogenesis in the brain of mice, and calls exercises that help refresh the brain at any age. Also, the authors of the project "Vesti. Science" (nauka.vesti.ru) wrote that the adult brain forms new neurons not only in the hippocampus.

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