We all know the expression that nerve cells do not regenerate. They thought so a few decades ago, but it turned out that this was not quite a true statement. Nerve cells are restored, and new neurons appear in the brain in adults. In both birds and mammals, neurogenesis has been confirmed, more than once.
In March
, an article was published on Geektimes, stating that adult neurogenesis is questionable. It either does not exist at all, or the rate of appearance of nerve cells is too low to consider the process important and significant. A small number of new neurons, the authors of the study found only in the brain of a 13-year-old. Now published the results of a new study, yet confirming neurogenesis in adults.
Moreover, the rate of formation of neurons, according
to the authors of this study, does not decrease with age. This discovery may be able to find a way to treat many age-related brain diseases, from Alzheimer's to psychiatric problems. Scientists published their thoughts on this subject in a work posted in the authoritative
publication Cell Stem Cell .
“It is impressive that neurons appear in the brain throughout life,” says study leader Maura Boldrini of Columbia University in New York. The brain of people is different in terms of the reproduction of nerve cells from the brain, for example, mice. “It seems that the human brain is constantly generating new cells, and this process is quite fast. This may mean that we need neurons to maintain our ability to learn and absorb new data. ”
Virdrini and her colleagues investigated the hippocampus of 28 men and women between the ages of 14 and 79. Brain cells were studied for several hours after the death of these people. At the same time about the people whose brain was studied, it is known that they were healthy before death. In many previous studies, roughly the same methods were used, but no one set out to study only the brains of adults.
Using a wide range of different methods and technologies, the team investigated the formation of new blood vessels, as well as the volume and number of nerve cells in the brain of people of different ages. Not the whole brain was studied, but only an organoid called the dentate fascia of the hippocampus. It was previously thought that here, as well as in the olfactory bulb and cerebellum, neurogenesis is possible.
In mammals, as it turned out, there is something like a reserve - stem cells that are not used in the normal state, they are inactive. But if necessary, the cells begin to turn into the kind that the body needs. As it turned out, the human stock of stem cells decreases with age, is depleted, primarily in the anterior and middle part of the dentate gyrus.
It also turned out that the new neurons received by the brain are less “neuroplastic”, which means their impaired ability to form connections with other neurons. Perhaps, according to experts, this factor explains the changes in the emotional state of older people - they become more vulnerable psychologically.
Now scientists are planning to study the occurring in the brain of Alzheimer's people. Perhaps the process of formation of new cells in patients with such a diagnosis is different than in healthy people.
Some experts who reviewed the results of the research above do not agree with the conclusions. According to Mercedes Paredes of the University of California, it’s early to draw conclusions about permanent neurogenesis. We need additional work that can confirm or deny the results of a study on the continuation of neurogenesis in adults.
For the first time, neurogenesis in adults of complex organisms
was proved using song birds as an example. In the spring, when they begin to sing, thousands of new neurons appear in the feathered brain. In the fall they disappear. In mammals, neurogenesis occurs in the subventricular zone, this is the region of the ventricles of the brain and in the hippocampus. In an adult, the appearance of neurons was shown by Peter Erickson in 1998.