As Leonid Bronevoy’s hero, the district doctor, said: “ the head is a dark object and cannot be examined..." Although the compact collection of nerve cells called the brain has been studied by neurophysiologists for a long time, scientists have not yet been able to obtain answers to all questions related to the functioning of neurons.
Essence of the question
Some time ago, until the 90s of the last century, it was believed that the number of neurons in the human body has a constant value and, if lost, it is impossible to restore damaged nerve cells in the brain. In part, this statement is indeed true: during the development of the embryo, nature lays down a huge reserve of cells.
Even before birth, a newborn baby loses almost 70% of its formed neurons as a result of programmed cell death - apoptosis. Neuronal death continues throughout life.
Starting from the age of thirty, this process is activated - a person loses up to 50,000 neurons every day. As a result of such losses, the brain of an old person is reduced by about 15% compared to its volume in youth and adulthood.
It is characteristic that scientists note this phenomenon only in humans.– in other mammals, including primates, age-related brain decline and, as a consequence, senile dementia are not observed. This may be due to the fact that animals in nature do not live to old age.
Scientists believe that the aging of brain tissue is a natural process established by nature and is a consequence of the longevity acquired by a person. A lot of the body’s energy is spent on brain function, so when increased activity is no longer necessary, nature reduces the energy consumption of brain tissue, spending energy on maintaining other body systems.
These data indeed support the common saying that nerve cells do not regenerate. Why, if the body in a normal state does not need to restore dead neurons - there is a supply of cells that is more than enough to last a lifetime.
Observations of patients suffering from Parkinson's disease have shown that clinical manifestations of the disease appear when almost 90% of the neurons in the midbrain, which is responsible for controlling movement, have died. When neurons die, their functions are taken over by neighboring nerve cells. They increase in size and form new connections between neurons.
So, if in a person's life "…everything goes according to plan", neurons lost in genetically determined quantities are not restored - this is simply not necessary.
More precisely, the formation of new neurons occurs. Throughout life, a certain number of new nerve cells are constantly produced. The brains of primates, including humans, produce several thousand neurons every day. But the natural loss of nerve cells is still much greater.
But the plan may go wrong. Massive neuronal death may occur. Of course, not due to a lack of positive emotions, but, for example, as a result of mechanical damage during injuries. This is where the ability to regenerate nerve cells comes into play. Scientists' studies prove that it is possible to transplant brain tissue, in which not only does the transplant not be rejected, but the addition of donor cells leads to the restoration of the recipient's nervous tissue.
The precedent of Teri Wallis
In addition to experiments on mice, the case of Terry Wallis, who spent twenty years in a coma after a severe car accident, can serve as evidence for scientists. Relatives refused to remove Terry from life support after doctors diagnosed a vegetative state.
After a twenty-year hiatus, Terry Wallis regained consciousness. Now he can already pronounce meaningful words and joke. Some motor functions are gradually restored, although this is complicated by the fact that over such a long period of inactivity, all the muscles of the man’s body have atrophied.
Scientists' studies of Terry Wallis' brain demonstrate phenomenal phenomena: Terry's brain is growing new neural structures to replace those lost in the accident.
Moreover, new formations have a shape and location different from the usual ones. The brain appears to grow new neurons where it feels most comfortable, rather than trying to replace those lost due to injury. Experiments conducted with patients in a vegetative state have proven that patients are able to answer questions and respond to requests. True, this can only be recorded by the activity of the brain system using magnetic resonance imaging. This discovery could radically change the attitude towards patients who have fallen into a vegetative state.
It is not only extreme situations such as traumatic brain injuries that can contribute to an increase in the number of dying neurons. Stress, poor diet, environment - all these factors can increase the number of nerve cells lost by a person. The state of stress also reduces the formation of new neurons. Stressful situations experienced during intrauterine development and the first time after birth can cause a decrease in the number of nerve cells in future life.
How to restore neurons
Instead of wondering whether it is possible to restore nerve cells at all, perhaps it is worth deciding - is it worth it? The report of Professor G. Hüther at the World Congress of Psychiatrists spoke about the observation of novices of a monastery in Canada. Many of the women observed were over a hundred years old. And all of them showed excellent mental and mental health: no characteristic degenerative changes of senility were found in their brains.
According to the professor, four factors contribute to maintaining neuroplasticity – the ability for brain regeneration:
- strength of social ties and friendly relations with loved ones;
- the ability to learn and the implementation of this ability throughout life;
- balance between what is desired and what is in reality;
- sustainable worldview.
The nuns had all these factors.
Despite the fact that neurogenesis was considered science fiction for a long time, and biologists unanimously claimed that it was impossible to restore lost neurons, in reality this turned out to be not at all the case. A person just needs to stick to healthy habits in his life.
Neurogenesis is a complex process in which the human brain creates new neurons and their connections.
To an ordinary person, at first glance, the process described above may seem too difficult to understand. Just yesterday, scientists from all over the world put forward the thesis that in old age the human brain loses its neurons: they split and this process is irreversible.
Moreover, it was assumed that injury or alcohol abuse doomed a person to an inevitable loss of mental flexibility (agility and brain activity), which characterizes a healthy person adhering to healthy habits.
But today a step has already been taken towards the word that gives us hope: and this word is - neuroplasticity.
Yes, it is absolutely true that our brain changes with age, that damage and bad habits (alcohol, tobacco) harm it. But the brain has the ability to regenerate; it can again create nerve tissue and bridge connections between them.
But in order for this amazing action to happen, a person must act, be active and stimulate the natural abilities of his brain in every possible way.
- everything you do and think about reorganizes your brain
- the human brain weighs only a kilogram and a half, and at the same time consumes almost 20% of all energy available in the body
- everything we do - read, study, or even just talk to someone - causes amazing changes in the structure of the brain. That is, absolutely everything we do and think is beneficial
- If our daily life is filled with stress or anxiety that literally takes over us, then, as a rule, regions such as the hippocampus (associated with memory) are inevitably affected
- the brain is like a sculpture that is formed from our emotions, thoughts, actions and daily habits
- such an internal map requires a huge number of “links”, connections, “bridges” and “highways”, as well as strong impulses that allow us to stay in touch with reality
5 Principles for Stimulating Neurogenesis
1. Exercise
Physical activity and neurogenesis are directly related.
Every time we exercise our body (be it walking, swimming or working out in the gym), we are oxygenating our brain, that is, saturating it with oxygen.
In addition to sending cleaner, more oxygenated blood to the brain, it also stimulates the production of endorphins.
Endorphins improve our mood and thus help us fight stress by strengthening many nerve structures.
In other words, any activity that reduces stress promotes neurogenesis. All you have to do is find a suitable type of activity (dancing, walking, cycling, etc.).
2. Flexible mind - strong brain
There are many ways to keep your mind flexible. To do this, you need to try to keep it in wakefulness mode, then it will be able to quickly “process” all incoming data (which comes from the environment).
This can be achieved through various activities. Leaving aside the above-mentioned physical activities, we note the following:
- reading - read every day, it maintains your interest and curiosity in everything that happens around you (and in new disciplines, in particular).
- studying of foreign language.
- playing a musical instrument.
- critical perception of things, search for truth.
- openness of mind, receptivity to everything around you, socialization, travel, discoveries, hobbies.
3. Diet
One of the main enemies of brain health is food rich in saturated fat. Consumption of processed and unnatural foods slows down neurogenesis.
- It is very important to try to stick to a low-calorie diet. But at the same time, nutrition should be varied and balanced so that there is no nutritional deficiency.
- Always remember that our brain needs energy, and in the morning, for example, it will be very grateful to us for something sweet.
- However, it is advisable to provide this glucose to him through a piece of fruit or dark chocolate, a spoonful of honey or a cup of oatmeal...
- And foods rich in Omega-3 fatty acids are undoubtedly the most suitable for maintaining and enhancing neurogenesis.
4. Sex helps too
Sex is another great architect of our brain, a natural driver of neurogenesis. Can't guess the reason for this connection? And here's the thing:
- Sex not only relieves tension and regulates stress, but also provides us with a powerful energy boost that stimulates the parts of the brain responsible for memory.
- And hormones such as serotonin, dopamine or oxytocin, produced during sexual intimacy with a partner, are beneficial for the creation of new nerve cells.
5. Meditation
The benefits of meditation for our brain are undeniable. The effect is as surprising as it is beautiful:
- Meditation promotes the development of certain cognitive abilities, namely attention, memory, and concentration.
- It allows us to better understand reality and correctly direct our anxieties and manage stress.
- During meditation, our brain works in a different rhythm: it produces higher alpha waves, which gradually generate gamma waves.
- This type of wave promotes relaxation while stimulating neurogenesis and neural communication.
While meditation does take some learning (it will take some time), be sure to do it as it is a wonderful gift for your mind and overall well-being.
In conclusion, we note that all these 5 principles that we talked about are actually not at all as complex as one might expect. Try to put them into practice and take care of the health of your brain.
Be calm with
ozg, restore yourself
N and throughout its 100-year history, neuroscience has adhered to the dogma that the adult brain is not subject to change. It was believed that a person could lose nerve cells, but not gain new ones. Indeed, if the brain were capable of structural changes, how would it be preserved?
The skin, liver, heart, kidneys, lungs and blood can form new cells to replace damaged ones. Until recently, experts believed that this ability to regenerate does not extend to the central nervous system, consisting of the brain and.
However, over the past five years, neuroscientists have discovered that the brain does change throughout life: new cells are formed to cope with emerging difficulties. This plasticity helps the brain recover from injury or disease, increasing its potential.
Neuroscientists have been looking for ways to improve brain health for decades. The treatment strategy was based on replenishing the lack of neurotransmitters - chemicals that transmit messages to nerve cells (neurons). In Parkinson's disease, for example, the patient's brain loses the ability to produce the neurotransmitter dopamine as the cells that produce it die. Dopamine's chemical cousin, L-Dopa, may provide temporary relief, but not a cure. To replace neurons that die in neurological diseases such as Huntington's disease, Parkinson's disease, and injury, neuroscientists are trying to implant stem cells derived from embryos. Recently, researchers have become interested in neurons derived from human embryonic stem cells, which, under certain conditions, can be induced to form any type of cell in the human body in Petri dishes.
Although stem cells have many benefits, it is clear that the adult nervous system should be developed to repair itself. To do this, it is necessary to introduce substances that stimulate the brain to form its own cells and restore damaged nerve circuits.
Newborn nerve cells
In the 1960s - 70s. The researchers concluded that the central nervous system of mammals is capable of regeneration. The first experiments showed that the main branches of neurons in the adult brain and axons can recover after damage. The birth of new neurons was soon discovered in the brains of adult birds, monkeys and humans, i.e. neurogenesis.
The question arises: if the central nervous system can form new ones, is it able to recover in the event of illness or injury? In order to answer it, it is necessary to understand how neurogenesis occurs in the adult brain and how it can be achieved.
The birth of new cells occurs gradually. So-called multipotent stem cells in the brain periodically begin to divide, giving rise to other stem cells that can grow into neurons, or supporting cells, called . But to mature, newborn cells must avoid the influence of multipotent stem cells, which only half of them succeed in - the rest die. This waste is reminiscent of the process that occurs in the body before birth and in early childhood, when more nerve cells are produced than are needed to form the brain. Only those who form valid connections with others survive.
Whether the surviving young cell becomes a neuron or a glial cell depends on where in the brain it ends up and what processes occur during this period. It takes more than a month for a new neuron to become fully functional. send and receive information. Thus. Neurogenesis is not a one-time event. and the process. which is regulated by substances. called growth factors. For example, a factor called “sonic hedgehog” (sonic hedgehog), first discovered in insects, regulates the ability of immature neurons to proliferate. Factor notch and class of molecules. called bone morphogenetic proteins, apparently determine whether a new cell will become glial or neural. As soon as this happens. other growth factors. such as brain-derived neurotrophic factor (BDNF). neurotrophins and insulin-like growth factor (IGF), begin to support the vital activity of the cell, stimulating its maturation.
Scene
It is not by chance that new neurons arise in the adult mammalian brain. apparently. are formed only in fluid-filled voids in the forebrain - in the ventricles, as well as in the hippocampus - a structure hidden deep in the brain. shaped like a seahorse. Neuroscientists have proven that cells that are destined to become neurons. move from the ventricles to the olfactory bulbs. which receive information from cells located in the nasal mucosa and sensitive to. No one knows exactly why the olfactory bulb requires so many new neurons. It's easier to guess why the hippocampus needs them: since this structure is important for remembering new information, additional neurons are likely. help strengthen connections between nerve cells, increasing the brain's ability to process and store information.
Neurogenesis processes are also found outside the hippocampus and olfactory bulb, for example, in the prefrontal cortex, the seat of intelligence and logic. as well as in other areas of the adult brain and spinal cord. Recently, new details have emerged about the molecular mechanisms that control neurogenesis and the chemical stimuli that regulate it. and we have the right to hope. that over time it will be possible to artificially stimulate neurogenesis in any part of the brain. By understanding how growth factors and the local microenvironment drive neurogenesis, researchers hope to create treatments that can restore diseased or damaged brains.
By stimulating neurogenesis, the patient's condition can be improved in some neurological diseases. For example. the reason is blockage of blood vessels in the brain, as a result of which neurons die due to lack of oxygen. After a stroke, neurogenesis begins to develop in the hippocampus, seeking to “heal” damaged brain tissue with new neurons. Most newborn cells die, but some successfully migrate to the damaged area and turn into full-fledged neurons. Despite the fact that this is not enough to compensate for damage in a severe stroke. Neurogenesis can help the brain after micro-strokes, which often go unnoticed. Now neuroscientists are trying to use vasculoepidermal growth factor (VEGF) and fibroblast growth factor (FGF) to enhance natural recovery.
Both substances are large molecules that have difficulty crossing the blood-brain barrier, i.e. a network of closely intertwined cells lining the blood vessels of the brain. In 1999, a biotechnology company Wyeth-Ayerst Laboratories and Scios from California suspended clinical trials of FGF used for. because its molecules did not enter the brain. Some researchers have tried to solve this problem by combining the molecule FGF with another, which misled the cell and forced it to capture the entire complex of molecules and transfer it to brain tissue. Other scientists have genetically engineered cells that produce FGF. and transplanted them into the brain. So far, such experiments have been carried out only on animals.
Stimulating neurogenesis may be effective in treating depression. the main cause of which (in addition to genetic predisposition) is considered chronic. limiting, as you know. number of neurons in the hippocampus. Many of the manufactured drugs. indicated for depression. including Prozac. enhance neurogenesis in animals. Interestingly, it takes one month to relieve depressive syndrome with the help of this drug - the same amount. as much as for the implementation of neurogenesis. Maybe. depression is partly caused by a slowing of this process in the hippocampus. Recent clinical studies using nervous system imaging techniques have confirmed this. that patients with chronic depression have a smaller hippocampus than healthy people. Long-term use of antidepressants. Seems like. stimulates neurogenesis: in rodents. who were given these drugs for several months. New neurons appeared in the hippocampus.
Neuronal stem cells give rise to new brain cells. They periodically divide in two main areas: the ventricles (purple), which are filled with cerebrospinal fluid, which nourishes the central nervous system, and in the hippocampus (blue), a structure necessary for learning and memory. During stem cell proliferation (at the bottom) New stem cells and progenitor cells are formed, which can develop into either neurons or supporting cells called glial cells (astrocytes and dendrocytes). However, differentiation of newborn nerve cells can only occur after they have moved away from their ancestors (red arrows), which, on average, only half of them succeed in, and the rest die. In the adult brain, new neurons were found in the hippocampus and olfactory bulbs, which are essential for the perception of smell. Scientists hope to force the adult brain to repair itself by causing neural stem or progenitor cells to divide and develop where and when needed.
Stem cells as a treatment method
Researchers consider two types of stem cells to be a potential tool for restoring damaged brains. First, adult brain neuronal stem cells: rare primordial cells preserved from early stages of embryonic development, found in at least two brain regions. They can divide throughout life, giving rise to new neurons and support cells called glia. The second type includes human embryonic stem cells, isolated from embryos at a very early stage of development, when the entire embryo consists of about a hundred cells. These embryonic stem cells can give rise to any cell in the body.
Most studies monitor the growth of neuronal stem cells in culture dishes. They can divide there, they can be genetically marked and then transplanted back into the nervous system of an adult individual. In experiments that have so far been carried out only on animals, the cells take root well and can differentiate into mature neurons in two areas of the brain where the formation of new neurons occurs normally - in the hippocampus and in the olfactory bulbs. However, in other areas, neuronal stem cells taken from the adult brain are slow to become neurons, although they may become glia.
The problem with adult neural stem cells is that they are still immature. If the adult brain into which they are transplanted does not produce the signals necessary to stimulate their development into a particular type of neuron - for example, a hippocampal neuron - they will either die, become a glial cell, or remain an undifferentiated stem cell. To address this question, it is necessary to determine what biochemical signals cause a neuronal stem cell to become a given type of neuron, and then direct the development of the cell along this path directly in the culture dish. Once transplanted into a given area of the brain, these cells are expected to remain the same type of neurons, form connections and begin to function.
Making important connections
Since it takes about a month from the time a neuronal stem cell divides until its descendant joins the brain's functional circuits, the role of these new neurons in the brain is likely determined less by the cell's lineage than by how the new and existing cells connect to each other. each other (forming synapses) and with existing neurons, forming nerve circuits. During synaptogenesis, so-called spines on the lateral branches, or dendrites, of one neuron connect to the main branch, or axon, of another neuron.
Recent studies show that dendritic spines (at the bottom) can change their shape within a few minutes. This suggests that synaptogenesis may underlie learning and memory. Single-color microphotographs of a living mouse brain (red, yellow, green and blue) were taken with an interval of one day. The multi-color image (far right) is the same photographs superimposed on top of each other. Areas that have not undergone changes appear almost white.
Help your brain
Another disease that provokes neurogenesis is Alzheimer's disease. As recent studies have shown, in mouse organs. which introduced human genes affected by Alzheimer's disease. Various deviations of neurogenesis from the norm were found. As a result of this intervention, the animal produces an excess of a mutant form of the precursor of human amyloid peptide, and the level of neurons in the hippocampus drops. And the hippocampus of mice with a mutant human gene. encoding the protein presenilin. had a small number of dividing cells and. respectively. fewer surviving neurons. Introduction FGF directly into the brain of animals weakened the trend; hence. Growth factors may be a good treatment for this devastating disease.
The next stage of research is the growth factors that control the various stages of neurogenesis (i.e., the birth of new cells, the migration and maturation of young cells), as well as the factors that inhibit each stage. To treat diseases such as depression, in which the number of dividing cells decreases, it is necessary to find pharmacological substances or other methods of intervention. enhancing cell proliferation. With epilepsy, apparently. new cells are born. but then they migrate in the wrong direction and need to be understood. how to direct “lost” neurons along the right path. In malignant brain glioma, glial cells proliferate and form deadly growing tumors. Although the causes of glioma are not yet clear. some believe. that it occurs as a result of the uncontrolled proliferation of brain stem cells. Glioma can be treated using natural compounds. regulating the division of such stem cells.
For stroke treatment, it is important to find out. what growth factors ensure the survival of neurons and stimulate the transformation of immature cells into healthy neurons. For such diseases. like Huntington's disease. amyotrophic lateral sclerosis (ALS) and Parkinson's disease (when very specific types of cells die, leading to the development of specific cognitive or motor symptoms). This process occurs most often because cells. with which these diseases are associated are located in limited areas.
The question arises: how to control the process of neurogenesis under one type of influence or another in order to control the number of neurons, since their excess also poses a danger? For example, in some forms of epilepsy, neuronal stem cells continue to divide even after new neurons have lost the ability to make useful connections. Neuroscientists suggest that the “wrong” cells remain immature and end up in the wrong place. forming the so-called fical cortical dysplasias (FCD), generating epileptiform discharges and causing epileptic seizures. It is possible that the introduction of growth factors during stroke. Parkinson's disease and other diseases can cause neural stem cells to divide too quickly and lead to similar symptoms. Therefore, researchers should first explore the use of growth factors to induce the birth, migration and maturation of neurons.
Treating spinal cord injury, ALS, or stem cells requires forcing stem cells to produce oligodendrocytes, a type of glial cell. They are necessary for neurons to communicate with each other. because they isolate long axons passing from one neuron to another. preventing the scattering of the electrical signal passing along the axon. It is known that stem cells in the spinal cord have the ability to occasionally produce oligodendrocytes. Researchers have used growth factors to stimulate this process in animals with spinal cord injury with positive results.
Exercise for the brain
One important feature of hippocampal neurogenesis is that the individual's personality can influence the rate of cell division, the number of surviving young neurons, and their ability to integrate into the neural network. For example. when adult mice are moved from ordinary and cramped cages to more comfortable and spacious ones. they experience a significant increase in neurogenesis. Researchers have found that training mice on a running wheel is enough to double the number of dividing cells in the hippocampus, leading to a dramatic increase in the number of new neurons. Interestingly, regular exercise can relieve depression in people. Maybe. this occurs due to the activation of neurogenesis.
If scientists learn to control neurogenesis, our understanding of brain diseases and injuries will change dramatically. For treatment, it will be possible to use substances that selectively stimulate certain stages of neurogenesis. Pharmacological effects will be combined with physical therapy, which enhances neurogenesis and stimulates certain areas of the brain to integrate new cells into them. Taking into account the relationship between neurogenesis and mental and physical activity will reduce the risk of neurological diseases and enhance natural reparative processes in the brain.
By stimulating the growth of neurons in the brain, healthy people will have the opportunity to improve their body condition. However, they are unlikely to appreciate injections of growth factors that have difficulty penetrating the blood-brain barrier once injected into the bloodstream. Therefore, experts are looking for drugs. which could be produced in tablet form. Such a medicine will stimulate the work of genes encoding growth factors directly in the human brain.
It is also possible to improve brain function through gene therapy and cell transplantation: artificially grown cells that produce specific growth factors. can be implanted into specific areas of the human brain. It is also proposed to introduce genes encoding the production of various growth factors and viruses into the human body. capable of delivering these genes to the desired brain cells.
It's not clear yet. which method will be the most promising. Animal studies show. that the use of growth factors may interfere with normal brain function. Growth processes can cause the formation of tumors, and transplanted cells can get out of control and trigger the development of cancer. Such a risk can only be justified in severe forms of Huntington's disease. Alzheimer's or Parkinson's.
The optimal way to stimulate brain activity is intense intellectual activity combined with a healthy lifestyle: physical activity. good nutrition and good rest. This is also confirmed experimentally. that connections in the brain are influenced by the environment. Maybe. One day, people's homes and offices will create and maintain specially enriched environments to improve brain function.
If we can understand the mechanisms of self-healing of the nervous system, then in the near future researchers will master the methods. allowing you to use your own brain resources for its restoration and improvement.
Fred Gage
(In the world of spiders, No. 12, 2003)