When nerve cells are restored. Only neurons will survive: How to restore nerve cells. Is it true that nerve cells do not regenerate?

Incredible facts

The adult brain contains about 86 billion nerve cells (or neurons). Throughout our lives, for various reasons, we gradually lose neurons (scientists say that the process of death of nerve cells starts at the age of 20–25, while after 40 it gains quite high momentum).

Why are new neurons needed?

It is neurons that are extremely important for learning, thought processes, the volume and quality of memory, mood and positive emotions.

By generating nerve cells on your own, you can not only prolong youth, but also prevent the severe consequences of neurodegenerative diseases: Parkinson's disease, Alzheimer's, Huntington's, multiple sclerosis, in which the nervous system is affected and cognitive and behavioral abnormalities develop.

New neurons are also necessary for healthy people, who by stimulating neurogenesis can significantly improve the condition of their body, master a larger amount of information and prevent memory problems in old age!

Is it possible to grow neurons?

For many years, neuroscientists gave a negative answer to this question: nerve cells do not recover.

But recent research suggests that new neurons are being formed in the adult brain (in the hippocampus, to be precise). This phenomenon is called neurogenesis.

Thus, Swedish researcher and neurologist Jonas Friesen from the Karolinska Institute calculated that about 700 new neurons are produced every day in the hippocampus (the gray mass in the center of the brain responsible for memory, emotions and learning).

Simple math: 700*365=255,500 neurons per year. Not enough, isn't it? Especially compared to 86 billion!

But that's not all! Neuroscientist Sandrine Thuret claims that over the course of 50 years of life, all the nerve cells we have at birth are replaced by neurons formed in the adult brain.

And again let's resort to mathematical calculations:

1. 50*365=18,250 (days).
2. 18,250*700=12,775,000 (neurons).

Question:where did the 86 billion neurons go?

Despite the controversial theories regarding the quantitative formation of new neurons in the hippocampus, we cannot exclude the fact that the creation of each new nerve cell is extremely important, since the cessation of neurogenesis leads to depression of a person’s psychological state, and this is fraught with depression and even psychosis.

In addition, additional neurons, regardless of their number, strengthen connections between nerve cells, thereby increasing the brain’s ability not only to process, but also to store information.

It is also interesting that even a damaged brain can produce neurons, and in an enhanced mode. This conclusion was reached by scientists from the University of Auckland, New Zealand, who studied people with Huntington's disease, which is characterized by decreased mental abilities and impaired coordination of movements.

The study revealed that the generation of new neurons occurred most intensively in the most affected tissues. Unfortunately, the number of new nerve cells formed is not enough to stop or cure the disease.

BUT! Knowing the conditions and factors that control neurogenesis and stimulate this process, scientists expect to find methods to help restore a diseased or damaged brain!

• Read also: Our brain is dying: these 10 tips will guarantee its long life

How to grow neurons at home?

Neuroscientists from around the world are actively researching neurons derived from human embryonic stem cells.

However, neuroscientist Sandrine Thuret says that we ourselves can contribute to the generation of new neurons and the self-healing of the nervous system.

Factors promoting neurogenesis

1. Training

• Read daily, as reading involves all types of mental activity. When reading a book, we think, look for cause-and-effect relationships, and use our imagination.
• Learn foreign languages: it has been proven that polyglots are much less likely to suffer from senile dementia, and with Alzheimer's disease they develop symptoms 5 years later.
• Learn to play a musical instrument: motor skills are closely related to the functioning of the brain, it stimulates its activity and increases neurogenesis.
• Travel and meet new people, discover new facets and opportunities.
• Master mnemonics, which is a set of techniques that make it easier to remember fairly large amounts of information. This brain training will enhance neurogenesis.

2. Running

In research conducted by Sandrine Thuret, it was found that in the hippocampus of a mouse whose cage was missing a wheel, much fewer new neurons were formed compared to a mouse whose cage was equipped with such a running device.

It can also be said that moderate physical activity in general also promotes neurogenesis, since during exercise, the level of cortisol (stress hormone) decreases and testosterone levels increase.

3. Sexual activity

The results of experiments conducted on rats showed that male pheromones activated the female reward system, as a result of which neurogenesis was also activated. However, such an effect cannot be confirmed experimentally in humans, so it is not possible to speak with 100% certainty about such a relationship.

In addition, sex reduces stress levels (the latter, in turn, reduces the formation of new neurons). Not to mention the fact that during sexual intercourse the level of serotonin and oxytocin, neurotransmitters that stimulate neurogenesis, increases.

4. Food

To stimulate neurogenesis, follow these rules:

• Increase the time between meals.
• Enrich your diet with foods containing flavonoids, including blueberries, dark chocolate, onions, garlic, spinach, citrus fruits, strawberries, and walnuts.
• Regularly eat fish containing Omega-3 fatty acids: salmon, halibut, sardines, fatty herring, mackerel, tuna.
• Pay attention to the texture of the food you eat: Japanese scientists have proven that soft food slows down neurogenesis, while hard food that requires careful chewing, on the contrary, activates it.

5. Sun

Fifteen minutes of daily sunbathing is enough to provide the body with the required amount of vitamin D, which affects the production of serotonin, which has a positive effect on the formation of new neurons.

• Read also: 10 little tricks that will help you become smarter

Factors that slow down neurogenesis

1. Age

With age, for physiological reasons, the rate of neurogenesis slows down.

2. Polluted air

The brain needs oxygen to function properly. If we inhale exhaust fumes and industrial dust for a long time, the brain experiences oxygen starvation, and changes occur in it that prevent neurogenesis.

3. Alcohol

Ethanol damages brain cells, thereby causing disturbances in brain function and weakening the process of formation of new nerve cells.

But the good news is that drinking red wine, which contains resveratrol, has been shown to help new neurons survive. Therefore, during feasts, give preference to good red wine, while remembering a sense of proportion.

4. Smoking and drugs

Brain cells are in a constant state of movement and development. Neural connections are formed until a person’s death. There is a common belief in the minds of the average person that nerve cells are not restored. Is it a myth or reality? To answer, it's worth thinking about one simple question.

The human brain contains approximately 90 billion neurons. Many negative factors of the external and internal environment: be it alcohol, unhealthy diet, stress, hormonal imbalances, etc., destroy nerve cells. Moreover, this process is constant. We are not talking about just one, but about hundreds and sometimes even thousands of neurons that a person loses per day. Perhaps not every day, but with enviable consistency.

Question: what would happen to the human brain and to its “carrier” itself if the statement “nerve cells do not recover” turned out to be true? The answer is obvious.

Recent research has shed some light. To put it briefly and clearly, the body is capable of synthesizing new neurons itself, which replace the old ones. The main participant in this process is the hippocampus. Part of one of the oldest parts of the brain, the limbic system. It synthesizes about 700 new structures per day. And so throughout life.

The statement that nerve cells do not regenerate is just a myth. But there is some common sense here. There are factors that actually inhibit the synthesis of new fibers.

What causes slow down the production of new nerve cells?

The process of synthesizing new neurons and restoring the structure of the brain is called neurogenesis. Normally, the hippocampus “supplies” about 700 such cytological structures per day. But this is an average. It decreases significantly if a person leads an unhealthy lifestyle. Some factors slow down the process of cerebral tissue renewal.

No intellectual load

This is not so much about a formal tension of mental forces, but about a new point of their application. Regular crossword puzzles and popular Japanese Sudoku puzzles are suitable for training. Logic puzzles and exercises, special programs and educational games. If a person does not receive enough intellectual load, there is a high probability of gradual degradation. For the same reasons, patients with a low degree of mental activity are at greater risk of encountering.

Same lifestyle

Generalized characteristics. In fact, it may be a static or toxic environment, monotonous work, stereotypical activity. Office workers and people engaged in routine work are most susceptible to this. Changes in environment are needed to renew cerebral structures. Even minimal, banal things are enough: going to work by a different route, changing the traditional daily routine, etc.

Excessive nutrition

Science does not yet know enough about the negative role of nutrition regarding the restoration of nerve cells. According to some estimates, exceeding the caloric intake of food by 20% per day almost halves the rate of synthesis of new neurons. It is still impossible to say how true this statement is and whether it applies to all people without exception.

It is clear, however, that insufficient intake of vitamins and an incorrect diet with excess salt and animal fat have a negative effect on neurogenesis.

Chronic stress

Prolonged psycho-emotional stress does not improve health. During stress, the adrenal glands produce a large amount of hormones: cortisol, adrenaline, etc. They inhibit the synthesis of neurons, slowing down the process.

Alcohol

Alcohol is a clear enemy of healthy cerebral structures. Ethanol and its breakdown products accumulate in brain tissue. Previously, there was an opinion that alcohol directly destroys fibers. This is not entirely true. Cytological structures do not disappear anywhere, formally the amount of substance remains at the same level. However, the processes of neurons are destroyed, which means that the signal no longer passes through them. From then on, they are excluded from normal activities and gradually die. The process is truly destructive, but it is extended over time. With systematic consumption of alcohol, disorders become more and more noticeable. The rate of neurogenesis drops by 50-70%, according to various estimates.

Use of certain drugs

Some drugs damage the brain. The use of psychotropic medications has a particularly negative effect on the condition of nerve cells. Recovering from them is not an easy task in itself. Tissues die as a result of blocking the transmission of nerve impulses. Special neurotransmitters are responsible for this process: dopamine and others. Such a harmful effect of neuroleptics and antidepressants is noticeable over the years. On MRI images of patients with a history, the size of the cerebral hemispheres is significantly smaller than in healthy people.

Lack of sleep

The body's biological clock is designed in such a way that closer to night the synthesis of cortisol weakens and melatonin is more actively produced. It is capable of inhibiting many biochemical processes, and therefore the metabolism in cerebral structures slows down. Toxins, which under normal conditions are quickly eliminated, are retained in tissues, poison them and provoke the death of cytological structures. With systematically incorrect sleep patterns, the process becomes more and more aggressive.

If we take these reasons to the absolute level - constantly drinking, forgetting about intellectual development, indeed - the nerve cells are not restored or the speed of this process is negligible. In other cases, neurogenesis slows down, but does not stop completely.

Does the opposite phenomenon occur when the intensity of neurogenesis increases? Yes, this is also possible.

What factors help restore nerve cells?

There are several ways to promote the natural recovery of nerve cells.

Rich emotional life

As a measure to prevent monotony. There is no need to work specifically in this direction. It is enough to maintain stable social connections, establish new contacts, communicate with people, change your way of activity from time to time, fully relax and not stay in one place. Positive emotions contribute to the production of neurotransmitters, substances that enhance neurogenesis.

Proper nutrition

By proper nutrition we mean a fortified diet. At a minimum, you need to adhere to a number of simple rules:

1. Limit salt intake to 4-6 grams per day. More is not necessary, since sodium ions cause narrowing of the arteries. Blood circulates worse, brain structures do not receive enough nutrients and oxygen. Consequently, they begin to work more slowly. Salt cannot be completely eliminated either. Without sodium, the electrolyte balance will quickly be disrupted. This is fraught with dangerous heart complications.
2. The diet should have enough vitamins. Their main source is fruits and vegetables. The share of plant foods should be about 50-60%. Plus or minus. It is best to discuss this issue with a nutrition specialist.
3. Animal fat should not be excluded from the diet. But on the menu it is given second place at best. Many essential amino acids can only be obtained from animal products. But preference should be given to dietary meats (chicken, turkey), fish and seafood.
4. Semi-finished products and canned food are completely eliminated from the menu. They contain huge doses of salt and a huge amount of chemical additives. Such products do not carry any useful load and provide nothing to the body.
5. A large role is also played by the drinking regime. Water is a universal solvent that accelerates metabolic processes. Normally, you need to consume about 2 liters per day, not counting liquid foods. If a person has kidney problems or hypertension, the amount of fluid is limited. The same is true if a woman is undergoing gestation. During pregnancy, the amount of fluid is calculated individually.

Regular intellectual exercise

Mental work helps restore brain neurons. There are many types of activities: crosswords, puzzles, reading books, analytical work, problem solving. A good help is studying the exact sciences: mathematics, physics. Also formal logic. It is necessary to constantly develop thinking: , (rational). Do special exercises. Living by these rules prevents two problems at once: on the one hand, it does not allow the brain to slowly die, on the other, it solves the issue of preventing dementia and Alzheimer's disease. In men, such pathologies are less common. But you still shouldn’t relax.

Healthy sleep in comfortable conditions is also an indispensable condition for the renewal of nerve structures.

There is no need to strive for world records. Scientists have proven that after an hour of training with moderate loads, the brain begins to work more actively. People who adhere to an active regime of physical activity are more capable of learning. Provided that these are feasible loads, and not grueling workouts for the sake of results or aesthetic goals.

In order to help your own body, just walking, cycling, skiing, or jogging in the morning is enough. It is important that physical activity is not too difficult. When exhausted, the reverse processes begin. Cortisol, adrenaline, and norepinephrine are produced. Moreover, in the same or greater quantities as during stress. Substances of the adrenal cortex block the functioning of the hippocampus.

Play activity

We are talking about any games: from old board games like checkers, chess to video games. In a seemingly simple way, the player looks for new ways to solve problems and finds himself in situations that require him to have a new way of thinking. Game techniques are much more effective than special exercises. Because the student spends much less energy on games, plays with great pleasure and is ready to devote a lot of time to the lesson.

In pursuit of neurogenesis, you need to observe moderation. Overwork triggers the opposite, harmful phenomena.

Why do you need to restore nerve cells at all?

There are many cases in medical history when a patient, by chance, lived without part of the brain, while working quite productively and even achieving success. Does this mean that the number of neurons does not matter? Not certainly in that way.

In all such cases, the patients either were in this state from birth or underwent a long and difficult rehabilitation course. Without brain renewal, intellectual activity, and not only that, becomes problematic. If you systematically follow lifestyle recommendations, you can achieve constant stable brain function and productive activity:

• new neural connections are formed constantly and without problems;
• learning ability increases;
• The speed of thinking also increases.

These are not idle and abstract practices. The task is quite specific - to create conditions for the brain to function at its maximum potential.

Restoring nerve cells: what to do to renew the brain

Summing up the interim results, we can give the following recommendations.

Avoid stress

How long does it take for nerve cells to recover and return to normal? The body needs at least a few days to do this. It is impossible to completely avoid stress, especially in modern conditions. Relaxation techniques come to the rescue: rhythmic breathing, visualization, counting to 10, etc. If desired, this question can be clarified with a psychotherapist.

Give up alcohol

Alcohol has a detrimental effect on cerebral structures. But what if a person has been drinking for some time, is it possible to restore nerve cells after drinking alcohol? Yes, you can. It will just take more time: part of it will be spent on returning to the position before the heavy “libations”, the rest will be spent on the actual development and renewal of tissues.

Consider adjusting your diet

Do nerve structures recover with proper nutrition? They are restored, this is the main goal of correcting your own eating habits.

Systematically engage in intellectual training

It is important to find a middle ground here. Excessive fatigue only causes harm. It is enough to develop a clear schedule of classes. It is advisable to practice in the first half of the day, when the body is still ready to perceive and analyze new information. Is it true that the heavier the load, the better? No, this will just lead to the opposite effect. You need to dose it correctly.

Get enough sleep

You need to sleep in a dark room, with the TV turned off and no network transmissions. Sleep duration is about 8-9 hours. More is possible, but not much. This is already an individual question. Half of your sleep should occur before 11 p.m. During this period, the body rests best.

Stop smoking too

How long does it take for brain neurons to recover if you eliminate cigarettes from everyday life? According to various estimates, 1.5-2 times faster. It is not so much nicotine that is dangerous as other chemical products: arsenic, cadmium, methane. They have the properties of neurotoxins. They not only slow down the recovery of nerve cells, but also destroy them themselves.

How fast does the recovery process proceed if a person follows all the recommendations? The question is individual. But a disciplined advocate of a healthy lifestyle will definitely get his “700 neurons”. There is another method to quickly return cerebral structures to normal. But it is dangerous and not suitable for everyone. We are talking about pharmacological assistance.

Is it possible to restore nerve cells with the help of drugs?

Medicines can be a good help for correcting the condition of cerebral structures. Is it always? No, not always. There needs to be a compelling reason to use drugs.

Indications (there are quite a few):

• hypertonic disease;
• symptomatic hypertension;
• encephalopathy of various types;
• previous stroke and acute emergency condition;
• various anomalies of the vascular structures of the brain;
• mental disorders;
• diseases of the vertebral arteries.

And some others. Against the background of pathologies of the cardiovascular and nervous systems, the recovery of nerve cells is slow. In some cases, so much so that natural renewal is not noticeable. This process has objective manifestations: thinking, mood swings, etc.

To spur the natural process, two groups of funds are used:

1. Nootropics are drugs that accelerate metabolic phenomena in nerve fibers: Glycine, Phenibut and the like. Increases the efficiency of energy metabolism. Simply put, the same amount of nutrients and oxygen is supplied, but they are spent more efficiently.
2. Cerebrovascular drugs - restore cerebral blood flow, reduce tissue oxygen demand: Piracetam, Actovegin.

Taking them uncontrollably is strictly prohibited. Is it dangerous. When there are suspicions, you need to go to a doctor: a neurologist, a cardiologist.

Vitamin and mineral complexes are used as more “peaceful” remedies. But even here you need to know when to stop. An excess of nutrients is just as dangerous as a deficiency, no matter how paradoxical it may sound.

In fact, nerve cells, that is, neurons, are restored. How does this happen and why?

There is a whole science - Neurogenesis. It turns out that by the age of 50 in a person, all the neurons that were present from birth are replaced by newly formed ones!

So why are these new neurons so important? First, they are needed for learning and memory. This has been proven experimentally. An experiment was carried out on rats.

During the experiments, mice were placed in similar but different environments on two treadmills. On one they smelled lemon and saw a pulsating light, on the other they smelled banana and saw a blue light. In one cage they received unpleasant shocks, in the other they did not. Normally, the animals associated a certain set of stimuli with a painful experience and, once again finding themselves in a “dangerous” cage, showed a stress reaction, freezing. However, if scientists purposefully “turned off” the activity of young abGCs in them using ontogenetics, no difference in behavior was noticed: the mice were equally afraid of both cells, without distinguishing between them.

That is, these neurons help us navigate the city.

Scientists are also confident that this also improves the quality of human memory. They help us differentiate between very similar memories. It's as if you parked your bike in a huge bike rack and were able to find exactly what you were looking for.

Relatively recently, with the recognition of neurogenesis in adults by the scientific community, the headlines of news sites were full of headlines: “Nerve cells are restored! We have been deceived since early childhood!”

However, neurogenesis in adults occurs in the subventricular zone (the area around the ventricles of the brain), the cells of which migrate to the olfactory bulb, and in the subgranular zone (the hippocampal region), which, however, does not prevent us from giving an affirmative answer to this question.

You can read more about embryonic and postembryonic neurogenesis in the relevant scientific works.

Of course, that they are being restored is already a rather outdated opinion that only circulates in everyday life. It is clear that for nerve cells this is not such a breeze as, for example, for epithelial cells, but still. There is a whole direction in neurobiology - neurogenesis. This process is classically studied in the hippocampus - a structure that is responsible for memory, spatial orientation, and is very sensitive to the negative effects of stress/depression.

Here are the latest scientific discoveries in this area

Jhaveri D. J. et al. Evidence for newly generated interneurons in the basolateral amygdala of adult mice // Molecular psychiatry. – 2018. – T. 23. – No. 3. – P. 521.

Wallace J. L., Wienisch M., Murthy V. N. Development and Refinement of Functional Properties of Adult-Born Neurons // Neuron. – 2018. – T. 97. – No. 3. – P. 727.

Schoenfeld T. J. et al. Stress and loss of adult neurogenesis differentially reduce hippocampal volume // Biological psychiatry. – 2017. – T. 82. – No. 12. – pp. 914-923.

Trinchero M. F. et al. High Plasticity of New Granule Cells in the Aging Hippocampus // Cell reports. – 2017. – T. 21. – No. 5. – pp. 1129-1139.

In short, these articles say that neurogenesis has already been discovered in the amygdala (amygdala) - a brain structure that, according to established ideas, is responsible for such emotional manifestations of our behavior as fear and anxiety. Light is shed on the process of neurogenesis in the brain of an adult animal, on how stress negatively affects this, and, on the contrary, physical activity has a positive effect.

Decades of discussions, long-established sayings, experiments on mice and sheep - but still, can the adult brain form new neurons to replace the lost ones? And if so, how? And if it can’t, why?

A cut finger will heal in a few days, a broken bone will heal. Myriads of red blood cells replace each other in short-lived generations, muscles grow under load: our body is constantly renewed. For a long time it was believed that there was one outsider left in this celebration of rebirth - the brain. Its most important cells, neurons, are too highly specialized to divide. The number of neurons is falling year by year, and although they are so numerous that the loss of several thousand does not have a noticeable effect, the ability to recover from damage would not hurt the brain. However, scientists have not been able to detect the presence of new neurons in the mature brain for a long time. However, there were not enough sophisticated tools to find such cells and their “parents”.

The situation changed when, in 1977, Michael Kaplan and James Hinds used radioactive [3H]-thymidine, which can be incorporated into new DNA. Its chains actively synthesize dividing cells, doubling their genetic material and at the same time accumulating radioactive labels. A month after administering the drug to adult rats, the scientists obtained slices of their brains. Autoradiography showed that the marks were located in the cells of the dentate gyrus of the hippocampus. Still, they reproduce, and “adult neurogenesis” exists.

About Men and Mice

During this process, mature neurons do not divide, just as muscle fiber cells and red blood cells do not divide: various stem cells that retain their “naive” ability to reproduce are responsible for their formation. One of the descendants of the divided progenitor cell becomes a young specialized cell and matures into a fully functional adult state. The other daughter cell remains a stem cell: this allows the population of progenitor cells to be maintained at a constant level without sacrificing the renewal of the surrounding tissue.

Neuronal precursor cells were found in the dentate gyrus of the hippocampus. Later they were found in other parts of the rodent brain, in the olfactory bulb and the subcortical structure of the striatum. From here, young neurons can migrate to the desired area of ​​the brain, mature in place, and integrate into existing communication systems. To do this, the new cell proves its usefulness to its neighbors: its ability to excite is increased, so that even a weak impact causes the neuron to produce a whole volley of electrical impulses. The more active a cell is, the more connections it forms with its neighbors and the faster these connections stabilize.

Adult neurogenesis in humans was confirmed only a couple of decades later with the help of similar radioactive nucleotides - in the same dentate gyrus of the hippocampus, and then in the striatum. Our olfactory bulb, apparently, is not renewed. However, how active this process is and how it changes over time is not exactly clear today.

For example, a 2013 study showed that until old age, approximately 1.75% of the cells in the dentate gyrus of the hippocampus are renewed each year. And in 2018, results emerged showing that the formation of neurons here stops already in adolescence. The first measured the accumulation of radioactive tracers, and the second used dyes that selectively bind to young neurons. It is difficult to say which conclusions are closer to the truth: it is difficult to compare rare results obtained by completely different methods, and even more so to extrapolate work done on mice to humans.

Model problems

Most studies of adult neurogenesis are conducted in laboratory animals, which reproduce quickly and are easy to maintain. This combination of signs is found in those who are small in size and live very short - in mice and rats. But in our brains, which only finish maturing by age 20, things can happen completely differently.

The dentate gyrus of the hippocampus is part of the cerebral cortex, albeit a primitive one. In our species, like in other long-living mammals, the cortex is noticeably more developed than in rodents. Perhaps neurogenesis covers its entire volume, being realized by some of its own mechanisms. There is no direct evidence of this yet: studies of adult neurogenesis in the cerebral cortex have not been performed either in humans or in other primates.

But such work has been carried out with ungulates. A study of brain sections of newborn lambs, as well as slightly older sheep and sexually mature individuals, did not find dividing cells - the precursors of neurons in the cerebral cortex and subcortical structures of their brains. On the other hand, in the cortex of even older animals, young neurons that were already born but immature were found. Most likely, they are ready to complete specialization at the right moment, forming full-fledged nerve cells and taking the place of the dead. Of course, this is not exactly neurogenesis, because new cells are not formed during this process. However, it is interesting that such young neurons are present in those areas of the sheep brain that in humans are responsible for thinking (cerebral cortex), integration of sensory signals and consciousness (claustrum), and emotions (amygdala). There is a high probability that we will also find immature nerve cells in similar structures. But why might an adult, already trained and experienced brain need them?

Memory hypothesis

The number of neurons is so large that some of them can be safely sacrificed. However, if a cell has switched off from working processes, this does not mean that it has died. The neuron may stop generating signals and responding to external stimuli. The information he has accumulated does not disappear, but is “preserved.” This phenomenon has led Carol Barnes, a neuroscientist at the University of Arizona, to theorize that this is how the brain stores and shares memories from different periods of life. According to Professor Barnes, from time to time a group of young neurons appears in the dentate gyrus of the hippocampus to record new experiences. After some time - weeks, months, and maybe years - they all go into a state of rest and no longer send signals. This is why memory (with rare exceptions) does not retain anything that happened to us before the third year of life: access to this data is blocked at some point.

Considering that the dentate gyrus, like the hippocampus as a whole, is responsible for transferring information from short-term memory to long-term memory, this hypothesis even seems logical. However, it still needs to be proven that the adult hippocampus actually produces new neurons, and in fairly large numbers. There is only a very limited set of possibilities for conducting experiments.

Stress story

Typically, human brain specimens are obtained during autopsy or neurosurgery, such as for temporal lobe epilepsy, where seizures are not treatable with drugs. Both options do not allow us to trace how the intensity of adult neurogenesis affects brain function and behavior.

Such experiments were carried out on rodents: the formation of new neurons was suppressed by targeted gamma radiation or by turning off the corresponding genes. This exposure increased the animals' susceptibility to depression. Mice incapable of neurogenesis were almost not happy about sweetened water and quickly gave up trying to stay afloat in a water-filled container. The content of cortisol, the stress hormone, in their blood was even higher than in mice stressed by conventional methods. They were more likely to become dependent on cocaine and had poorer recovery from stroke.

It is worth making one important note about these results: it is possible that the shown connection “fewer new neurons - a sharper reaction to stress” closes on itself. Unpleasant life events reduce the intensity of adult neurogenesis, which makes the animal more sensitive to stress, so the rate of formation of neurons in the brain decreases - and so on in a circle.

Business on nerves

Despite the lack of accurate information about adult neurogenesis, businessmen have already appeared who are ready to build a profitable business on it. Since the early 2010s, a company that sells water from springs in the Canadian Rockies has been producing bottles Neurogenesis Happy Water. It is claimed that the drink stimulates the formation of neurons due to the lithium salts it contains. Lithium is indeed considered a drug that is beneficial for the brain, although there is much more of it in tablets than in “happy water”. The effect of the miracle drink was tested by neuroscientists from the University of British Columbia. They gave rats “happy water” for 16 days, and a control group - plain water from the tap, and then examined slices of the dentate gyrus of their hippocampus. And although the rodents who drank Neurogenesis Happy Water, as many as 12% more new neurons appeared, their total number turned out to be small and it is impossible to talk about a statistically significant advantage.

For now, we can only state that adult neurogenesis clearly exists in the brain of representatives of our species. Perhaps it continues until old age, or maybe only until adolescence. It's actually not that important. What is more interesting is that the birth of nerve cells in the mature human brain generally occurs: from the skin or from the intestines, the renewal of which occurs constantly and intensively; the main organ of our body differs quantitatively, but not qualitatively. And when the information about adult neurogenesis comes together into a complete, detailed picture, we will understand how to translate this quantity into quality, forcing the brain to “repair”, restore the functioning of memory, emotions - everything that we call our life.