Plastic brain. neuroplasticity of the brain. Exercises aimed at stimulating neuronal plasticity and neurogenesis. What is neuroplasticity

Doctor of Biological Sciences E. P. Kharchenko, M. N. Klimenko

plasticity levels

At the beginning of this century, brain researchers abandoned traditional ideas about the structural stability of the adult brain and the impossibility of forming new neurons in it. It became clear that the plasticity of the adult brain also uses the processes of neurogenesis to a limited extent.

When talking about the plasticity of the brain, most often they mean its ability to change under the influence of learning or damage. The mechanisms responsible for plasticity are different, and its most perfect manifestation in brain damage is regeneration. The brain is an extremely complex network of neurons that communicate with each other through special education- synapses. Therefore, we can distinguish two levels of plasticity: macro and micro levels. The macro level is associated with a change in the network structure of the brain that provides communication between the hemispheres and between different areas within each hemisphere. At the micro level, molecular changes occur in the neurons themselves and in the synapses. At both levels, brain plasticity can manifest itself both quickly and slowly. In this article, we will focus mainly on plasticity at the macro level and on the prospects for research on brain regeneration.

There are three simple scenarios for brain plasticity. In the first, damage to the brain itself occurs: for example, a stroke in the motor cortex, as a result of which the muscles of the trunk and limbs lose control from the cortex and become paralyzed. The second scenario is the opposite of the first: the brain is intact, but the organ or department is damaged nervous system on the periphery: sensory organ - ear or eye, spinal cord, amputated limb. And since, at the same time, information ceases to flow into the corresponding parts of the brain, these parts become “unemployed”, they are not functionally involved. In both scenarios, the brain is reorganized, trying to fill the function of damaged areas with the help of undamaged ones, or to involve "unemployed" areas in the maintenance of other functions. As for the third scenario, it is different from the first two and is associated with mental disorders caused by various factors.

A bit of anatomy

On fig. 1 shows a simplified diagram of the location on the outer cortex of the left hemisphere of the fields described and numbered in the order of their study by the German anatomist Korbinian Brodmann.

Each Brodmann field is characterized by a special composition of neurons, their location (the neurons of the cortex form layers) and connections between them. For example, the fields of the sensory cortex, in which the primary processing of information from sensory organs, differ sharply in their architecture from the primary motor cortex, which is responsible for the formation of commands for voluntary muscle movements. The primary motor cortex is dominated by neurons resembling pyramids in shape, and the sensory cortex is represented mainly by neurons whose body shape resembles grains, or granules, which is why they are called granular.

Usually the brain is divided into anterior and posterior (Fig. 1). The areas of the cortex adjacent to the primary sensory fields in the hindbrain are called associative zones. They process information coming from primary sensory fields. The further away from them the associative zone, the more it is able to integrate information from different areas of the brain. The highest integrative capacity in the hindbrain is characteristic of the associative zone in the parietal lobe (not colored in Fig. 1).

AT forebrain the premotor cortex is adjacent to the motor cortex, where additional centers for regulating movement are located. At the frontal pole there is another extensive associative zone - the prefrontal cortex. In primates, this is the most developed part of the brain, responsible for the most complex mental processes. It is in the associative zones of the frontal, parietal and temporal lobe in adult monkeys, the inclusion of new granular neurons with a short lifespan of up to two weeks was revealed. This phenomenon is explained by the participation of these zones in the processes of learning and memory.

Within each hemisphere, nearby and distant regions interact with each other, but sensory regions within a hemisphere do not communicate directly with each other. Homotopic, that is, symmetrical, regions of different hemispheres are interconnected. The hemispheres are also connected with the underlying, evolutionarily older subcortical regions of the brain.

Brain reserves

Impressive evidence of brain plasticity comes from neuroscience, especially in last years, with the advent of visual methods for studying the brain: computer, magnetic resonance and positron emission tomography, magnetoencephalography. The images of the brain obtained with their help made it possible to make sure that in some cases a person is able to work and study, to be socially and biologically complete, even having lost a very significant part of the brain.

Perhaps the most paradoxical example of brain plasticity is the case of hydrocephalus in a mathematician, which led to the loss of almost 95% of the cortex and did not affect his high intellectual abilities. The journal Science published an article on this subject with the ironic title "Do we really need a brain?".

More often, however, significant brain damage leads to profound lifelong disability- its ability to restore lost functions is not unlimited. Common Causes of Brain Damage in Adults cerebral circulation(in most severe manifestation- stroke), less often - injuries and tumors of the brain, infections and intoxications. In children, there are frequent cases of brain development disorders associated with both genetic factors, and with the pathology of intrauterine development.

Among the factors that determine the regenerative abilities of the brain, first of all, the age of the patient should be singled out. Unlike adults, in children, after the removal of one of the hemispheres, the other hemisphere compensates for the functions of the remote one, including language. (It is well known that in adults, the loss of the functions of one of the hemispheres is accompanied by speech disorders.) Not all children compensate equally quickly and completely, but a third of children at the age of 1 year with paresis of the arms and legs get rid of violations by the age of 7 years. motor activity. Up to 90% of children with neurological disorders in the neonatal period subsequently develop normally. Therefore, the immature brain is better able to cope with damage.

The second factor is the duration of exposure to the damaging agent. A slowly growing tumor deforms the parts of the brain closest to it, but can reach an impressive size without disturbing the functions of the brain: it has time to turn on compensatory mechanisms. However acute disorder the same scale is most often incompatible with life.

The third factor is the location of brain damage. Small in size, the damage may affect the area of dense accumulation nerve fibers going to various departments body and cause serious illness. For example, through small areas of the brain called internal capsules (there are two of them, one in each hemisphere), fibers of the so-called pyramidal tract (Fig. 2) pass from the motor neurons of the cerebral cortex, which goes to the spinal cord and transmits commands to all the muscles of the body and limbs. So, a hemorrhage in the area of the internal capsule can lead to paralysis of the muscles of the entire half of the body.

The fourth factor is the extent of the lesion. In general, the larger the lesion, the more loss of brain function. And since the basis of the structural organization of the brain is a network of neurons, the loss of one section of the network can affect the work of other, remote sections. That is why speech disorders are often noted when brain areas are affected that are located far from specialized areas of speech, such as Broca's center (fields 44-45 in Fig. 1).

Finally, in addition to these four factors, individual variations in the anatomical and functional connections of the brain are important.

How is the cortex reorganized

We have already said that the functional specialization of different areas of the cerebral cortex is determined by their architecture. This evolutionary specialization serves as one of the barriers to the manifestation of brain plasticity. For example, if the primary motor cortex is damaged in an adult, its functions cannot be taken over by the sensory areas located next to it, but the premotor zone of the same hemisphere adjacent to it can.

In right-handed people, when Broca's center associated with speech is disturbed in the left hemisphere, not only the areas adjacent to it are activated, but also the area homotopic to Broca's center in the right hemisphere. However, such a shift of functions from one hemisphere to another does not go unnoticed: overloading the area of the cortex that helps the damaged area leads to a deterioration in the performance of its own tasks. In the described case, the transfer of speech functions to the right hemisphere is accompanied by a weakening of the patient's spatial-visual attention - for example, such a person may partially ignore (not perceive) left side space.

Brain music. Rules for the harmonious development of Pren Anet

Brain plasticity

So why can we play on our own brain as musical instrument? The main thing is plastic brain, its ability to change.

Until the early 1990s, most researchers believed that all nerve cells a person receives at birth and that after twenty-five years they begin to die off, gradually weakening the strength and complexity nerve connections.

But today, thanks to advanced technologies, the opinion of scientists on this issue has changed radically. It is now known that the human brain contains about a hundred billion neurons, connected to each other through the so-called synapses, and that throughout our lives every day, at least two hundred new nerve cells are created in the memory zone alone. In other words, our brain is in a state of permanent change.

Our brain is in a state of constant change.

In addition, a few years ago, researchers believed that specific centers are responsible for speech, feelings, vision, balance, etc. Today, scientists have come to the conclusion that this is not entirely true. The basic functions that control our motor activity and sensory feedback are indeed localized in specific areas of the brain, but complex cognitive functions are distributed across different areas of the brain. All eight keys presented in this book correspond to different areas of the brain, however, no key is limited to any one part of it.

For example, the function of speech is the result of the command activity of a number of brain regions that can cooperate with each other. different ways. This explains why each person uses their own unique speech constructions and why the structure of our speech changes depending on the environment.

In addition, the brain is constantly reorganized. The researchers found that weakened brain functions can be restored with others areas of the brain. Psychiatrist Norman Doidge considers one of the greatest discoveries of the 20th century to be the fact that practical and theoretical learning and action can "turn our genes on and off, shaping the anatomy of our brain and our behavior." And the neurologist Vilayanur Subramanian Ramachandran calls the discoveries made in recent years in the field brain activity fifth revolution.

Practical and theoretical learning and action can turn our genes on and off.

However, it must be admitted that today scientists are only on the threshold of knowing countless miracles. human brain. And after reading this book, you will come to understand only a small, albeit extremely important, part of these miracles.

This book talks about both the biological and mental components of the brain, but mostly about the latter. The biological part concerns the chemistry and physics of the brain, neurotransmitters such as serotonin and dopamine, and neuronal plasticity. The mental component concerns our ability to think and act, as well as cognition in the broadest sense of the word.

At this point, the reader may be wondering, “But I already know a lot about the brain—what else do I need to know?” Trust me, there are plenty of surprises in store for you, as many of the entrenched ideas about the brain are outdated today. For example, scientists used to think that the deeper they penetrated into the brain, the further they could advance in the knowledge of human evolution, and that the "civilized" cerebral cortex was responsible for basic and primitive functions. So: you will have to reconsider this popular theory. Our brain does not consist of evolutionary layers: it cannot be considered a modular design at all. It functions more like a network, it is much more complex and interesting than we can imagine.

And our other readers may say: "We are what we are, and all this talk about positive changes is nothing more than another empty promise." But you forget about plasticity - essential quality brain: it is malleable and constantly changing, adapting to the environment. Today you use some nerve cells when performing this or that action, and in a couple of weeks, doing the same, already different. For example, after you read this book, your brain will never be the same again.

A person develops his brain constantly when he makes the next choice or learns something new in Everyday life. A good example of the plasticity of the brain can serve as the famous London taxi drivers. From two to four years they prepare and train: they memorize street names, routes and sights within a radius of ten kilometers from the city center. Studies have shown that as a result of this, their right hippocampus is enlarged - compared to representatives of other professions - and spatial memory is noticeably improved. And the more the taxi driver, driving around the city, memorizes new information, the larger this part of the brain becomes. Think: what parts of the brain you train and develop in everyday life? Which of them are trained better than others?

Some feel that change is not for them at all. They reason like this: "I'm too old, and you can't teach an old dog new tricks." However, today it has already been proven that excited neurons produce 25% more nerve connections, increase in size and improve blood supply to the brain, and this happens at any age. A person can change no matter how old he is. It doesn't have to happen overnight, although it is possible. One new knowledge, a little appropriate adjustment and refinement - and what seemed insurmountable recently, suddenly looks completely different, and you find yourself acting in a completely different way.

Excited neurons produce 25% more neural connections.

In the life of every person there are examples of both types of change - both as a result of purposeful practical training, and as a result of sharp leaps in understanding that literally overnight change our way of life. and understanding of ourselves, the world around us and the opportunities available to us.

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September 6, 2016 at 03:25 pm

Neuroplasticity: Reshaping the Brain

Popular Science,
Brain

Translation

Our brains are remarkably plastic. Not like plastic dishes or a Barbie doll – in neuroscience, plasticity refers to the amazing ability of the brain to change and adapt to almost everything that happens to us. In the old days, scientists believed that when a person ceased to be a child, his brain froze like a clay pot and remained in one form. But piles of research have refuted their opinion - the brain is more like plasticine. These changes can occur at different scales: from a single neuron changing connections to an entire cortical area shrinking or swelling. Many factors can change the structure of the brain, from injuries and strokes, to meditation, exercise, or daily piano practice. And like everything in life, plasticity is a double-edged sword. The upside is that the brain can rewire itself during stroke rehabilitation. Minus - phantom pain after the loss of a limb. Let's see how, what and why happens.

Let's start with small scales and synaptic plasticity (if you don't know what a synapse is, read first). This kind of plasticity, often referred to as long-term potentiation (LTP) and long-term suppression (LTD), is critical to our understanding of memory and learning. In a very simplified way, it works like this: the connections between neurons are strengthened or weakened (potentiation or depression occurs) depending on their actions. When neuron A constantly fires neuron B, the connection between them is strengthened.

Naturally, this usually happens on several synapses - this is how entire networks can appear, in case they enough once it was in this composition that they showed activity (and we believe that memory is formed in much the same way). So kiss your soul mate often enough while listening to Lou Beg's compositions, and soon the song "Mambo number five" will make you feel romantic. Donald Hebb, a Canadian neuropsychologist, coined the saying "Run Together, Braid Together" to describe this process. Initially, these bonds are fragile, but if you activate them enough times, they will become strong (they cannot be separated, like Britney and Justina in 99). The reverse process, DPD, is triggered by another stimulation routine and is thought to loosen unnecessary ties - forgetting your ex's name or ennobling new dance moves. Synapse plasticity is a concept that cognitive and behavioral therapists recommend to their patients: in order to change established thought patterns, you need to form new ones step by step through practice. And new paths evolve from dirt roads to highways (on which healthy behavior moves), and broken contours float away into oblivion.

Plasticity on large scales manifests itself in a different way. A growing body of research shows that the more you use a particular muscle, the more area your brain dedicates to it. For example, one study shows that although the areas responsible for finger movements usually have same size, it is not permanent. After five days of piano practice, definite and quite visible changes in the motor cortex. The areas responsible for finger movements expanded and took over other parts of neighboring areas, like weeds growing in a garden. The researchers went even further: they showed that even if the subjects thought about exercise, the effect was almost the same! mental exercises proved to be just as effective in reorganizing the structure of the brain as physical ones. Another example (of which neuroscience students have probably heard more than those living in the Bible Belt—a region of the US where Protestant fundamentalism is particularly strong—about Jesus) are London taxi drivers. Experienced taxi drivers who have to memorize a map of the capital, including tens of thousands of streets and dozens of landmarks, have a large posterior hippocampus, the brain structure responsible for spatial memory and orientation. The control group, bus drivers with regular and established routes, had a normal-sized hippocampus. To forestall the usual “correlation does not guarantee causation” comments (perhaps it was increased hippocampal size that got the taxi drivers to do this job?), the researchers showed that increased hippocampal volume was positively correlated with time spent on the steering wheel. The more you drive, the more your brain adapts.

Do you already agree that the brain is incredibly plastic? Don't rush, we have more examples. If you've given up on meditation as hippie bullshit, take note: long-term meditation practice is associated with some very positive changes in the brain. Think of it like a workout - like piano lessons. Research shows that if you sit still and meditate, you can increase the thickness of the cortex (that is, more gray cells, that is, more neurons for signal processing) in areas associated with attention, memory and emotion management. Moreover, the amygdala, the center of responses associated with fear and disgust, shrinks and weakens connections with the prefrontal cortex of the brain, the place where higher executive functions are located. Simply put, meditation allows you to respond to stress more thoughtfully and suppress instincts. Last but not least, the dormant brain network responsible for self-determination and daydreaming also reduces activity, which allows for less distraction (and prevents thoughts from jumping from yesterday's party to the inevitability of death or something like that). And while I'm here doing covert propaganda healthy lifestyle, I will mention that they also change your brain for the better physical exercises. Only three hours brisk walking per week increases the growth and birth of nerve cells, which, in turn, prevents age-related brain shrinkage. Research shows that the anterior regions and the hippocampus especially benefited from this - that is, their volume increased after prolonged exercise. Here is an example of how memory and reasoning ability are improved thanks to a healthy lifestyle.

Your brain, like an ideal spouse, exists with you in Good times and in bad, in sickness and in health. After an injury or stroke, neuroplasticity helps you. Rehabilitation training after a stroke or injury has shown that the brain is reorganizing around the damaged region. Suppose a stroke damaged the part of the brain responsible for the movements of the left hand. The use of a technology called "forced movement restriction therapy" (where you are forced to use the "bad" hand, while the other hand is restricted in movement), leads to an increase in the volume of gray matter in the motor region, changes the regions adjacent to the damaged so that they take over its functions and even force the contralateral hemisphere to participate in the recovery. The brain rewires itself to adapt to new circumstances and make it happen the best way. However, it doesn't always go so well. Sometimes the brain can screw up and get you in trouble - that's me about phantom pains. You've probably heard of people who still have the feeling of an amputated arm or leg. This is also the merit of our restless plastic brain, although this process has not been 100% studied. One of the generally accepted theories says that the area of the somatosensory cortex, adjacent to the one responsible for the functions of the missing limb, grabs onto new opportunity and fills the vacancy. For example, the area of the face is located next to the area of the hands. And if you lose your hand, the area of the face takes the place of its neighbor and perceives all the sensations of the face doubly: both coming from the cheek and from the non-existent thumb.

It becomes clear that we are not limited to the cards that nature has given us: it is possible to change some of them (and this will not even be perceived as cheating). The brain reflects our environment, our decisions, emotions and lifestyle, and it's never too late to change all of this, in fact.

When we learn or receive new experience, the brain sets the series neural connections. These neural circuits are the pathways by which neurons exchange information with each other.

Structure and organization

“Brain plasticity refers to the ability of the nervous system to change its structure and function throughout life in response to diversity. environment. This term is not so easy to define, even though it is currently widely used in psychology and neuroscience. It is used to refer to changes in various levels nervous system: in molecular structures, changes in gene expression and behavior".

Neuroplasticity allows neurons to regenerate both anatomically and functionally, as well as to create new synaptic connections.

Neural plasticity is the ability of the brain to repair and restructure. This adaptive potential of the nervous system allows the brain to recover from injuries and disorders, and can also reduce the effects of structural changes caused by pathologies such as multiple sclerosis, Parkinson's disease, cognitive impairment, Alzheimer's disease, dyslexia, ADHD, insomnia in adults, insomnia in children, etc.

Studies have shown that brain plasticity is activated and strengthened by this clinical exercise program. In the figure below, you can see how the neural network develops as a result of constant and appropriate cognitive stimulation.

Neural networks before training, Neural networks after 2 weeks of cognitive stimulation, Neural networks after 2 months of cognitive stimulation

Synaptic plasticity

When we learn or experience new things, the brain establishes a series of neural connections. These neural circuits are the pathways by which neurons exchange information with each other. These paths are formed in the brain during learning and practice, as, for example, a path is formed in the mountains if a shepherd walks along it daily with his flock. Neurons communicate with each other through connections called synapses, and these communication pathways can regenerate over a lifetime.

Each time we acquire new knowledge (through constant practice), communication or synaptic transmission between the neurons involved in the process is enhanced.

Improved communication between neurons means that electrical signals are more efficiently transmitted throughout the new path. For example, when you try to recognize what kind of bird is singing, new connections are formed between some neurons. So, the neurons of the visual cortex determine the color of the bird, the auditory cortex - its singing, and other neurons - the name of the bird. Thus, in order to identify a bird, you need to repeatedly compare its color, voice, name. With each new attempt, when returning to the neural circuit and restoring neural transmission between the neurons involved in the process, the efficiency of synaptic transmission increases. Thus, the communication between the corresponding neurons is improved, and the process of cognition is faster each time. Synaptic plasticity is the basis of human brain plasticity.

neurogenesis

After 1944, and especially in recent years, the existence of neurogenesis was scientifically proven, and today we know what happens when stem cells ( special kind cells located in the dentate gyrus, hippocampus, and possibly in the prefrontal cortex) are divided into two cells: a stem cell and a cell that will turn into a full-fledged neuron, with axons and dendrites. After that, new neurons migrate to various areas(including distant from each other) of the brain, to where they are needed, thereby maintaining the neural capacity of the brain. It is known that both in animals and humans, sudden neuronal death (for example, after a hemorrhage) is a powerful stimulus for triggering the process of neurogenesis.

Functional Compensatory Plasticity

The neuroscience literature has covered the topic of cognitive decline with aging and explained why older people exhibit lower cognitive performance than younger people. Surprisingly, not all older people show poor performance: some perform just as well as younger people.

These unexpectedly different results in a subgroup of people of the same age were scientifically investigated, as a result of which it was found that when processed new information older people with greater cognitive performance use the same brain regions as younger people, as well as other brain regions that are not used by either young or other older participants in the experiment.

This phenomenon of overuse of the brain by the elderly has been investigated by scientists who concluded that the use of new cognitive resources occurs as part of a compensatory strategy. As a result of aging and a decrease in synaptic plasticity, the brain, demonstrating its plasticity, begins to restructure its neurocognitive networks. Research has shown that the brain arrives at this functional decision by activating other neural pathways, more often involving areas in both hemispheres (which is usually characteristic only for younger people).

Functioning and Behavior: Learning, Experience and Environment

The brain learns throughout our lives - at any moment and according to different reasons we get new knowledge. For example, children acquire new knowledge in huge quantities, which provokes significant changes in brain structures during periods of intense learning. New knowledge can also be obtained as a result of neurological trauma experienced, for example, as a result of damage or hemorrhage, when the functions of the damaged part of the brain are impaired, and you need to learn anew. There are also people with a thirst for knowledge, for which it is necessary to constantly study.

In connection with huge amount circumstances under which new training may be required, we wonder if does the brain change every time?

Researchers believe this is not the case. It appears that the brain acquires new knowledge and demonstrates its potential for plasticity if the new knowledge helps improve behavior. That is, for physiological changes brain requires that learning results in behavioral change. In other words, new knowledge must be needed. For example, knowledge about another way to survive. Probably, the degree of usefulness plays a role here. In particular, they help to develop brain plasticity. interactive games. This form of learning has been shown to increase the activity of the prefrontal cortex (PFC). In addition, it is useful to play with positive reinforcement and reward, which is traditionally used in teaching children.

Conditions for the implementation of brain plasticity

When, at what point in life is the brain most susceptible to changes under the influence of environmental factors? Brain plasticity seems to be age-dependent, and there are still many discoveries to be made about the influence of the environment on it depending on the age of the subject.

However, we are aware that mental activity both healthy elderly people and elderly people suffering from a neurodegenerative disease, has a positive effect on neuroplasticity. The important thing is that the brain is subject to both positive and negative changes even before a person is born. Animal studies have shown that when mothers-to-be are surrounded by positive stimuli, babies form more synapses in certain areas of the brain. Conversely, when bright light was turned on during pregnancy, which introduced them into a state of stress, the number of neurons in the prefrontal cortex (PFC) of the fetus decreased. In addition, the PFC appears to be more sensitive to environmental influences than the rest of the brain.

The results of these experiments have importance in the nature versus environment argument, as they demonstrate that the environment can change neuronal gene expression.

How does brain plasticity evolve over time, and what is the result of environmental influences on it? This question is the most important for therapy.

Conducted genetic research animals have shown that some genes change even after a short exposure, others - as a result of more prolonged exposure, while there are also genes that could not be influenced in any way, and even if it was possible, as a result, they still returned to their original state.

Although the term "plasticity" of the brain carries a positive connotation, in fact, by plasticity we also mean negative changes in the brain associated with dysfunctions and disorders. Cognitive training is very helpful in stimulating positive brain plasticity. With the help of systematic exercises, you can create new neural circuits and improve synaptic connections between neurons. However, as we noted earlier, The brain does not learn effectively if learning is not rewarding. Therefore, when learning, it is important to set and achieve your personal goals.. published

"Brain plasticity refers to the ability of the nervous system to change its structure and function throughout life in response to the diversity of the environment. This term is not so easy to define even though it is currently widely used in psychology and neuroscience. It is used to denote changes that occur at various levels of the nervous system: in molecular structures, changes in gene expression and behavior.

Neuroplasticity allows neurons to regenerate both anatomically and functionally, as well as to create new synaptic connections. Neural plasticity is the ability of the brain to repair and restructure. This adaptive potential of the nervous system allows the brain to recover from injuries and disorders and can also reduce the effects of structural changes caused by pathologies such as multiple sclerosis, Parkinson's disease, cognitive impairment, insomnia in children, etc.

Various groups of neuroscientists and cognitive psychologists studying the processes of synaptic plasticity and neurogenesis have concluded that the CogniFit battery of cognitive clinical exercises for brain stimulation and training promotes the creation of new synapses and neural circuits that help reorganize and restore the function of the damaged area and transfer of compensatory abilities. Studies have shown that brain plasticity is activated and strengthened by this clinical exercise program. In the figure below, you can see how the neural network develops as a result of constant and appropriate cognitive stimulation.

Neural networks before workoutsNeural networks after 2 weeks cognitive stimulationNeural networks after 2 months cognitive stimulation

Synaptic plasticity

When we learn or experience new things, the brain establishes a series of neural connections. These neural networks are the pathways by which neurons exchange information with each other. These paths are formed in the brain during learning and practice, as, for example, a path is formed in the mountains if a shepherd walks along it daily with his flock. Neurons communicate with each other through connections called synapses, and these communication pathways can regenerate over a lifetime. Each time we acquire new knowledge (through constant practice), communication or synaptic transmission between the neurons involved in the process is enhanced. Improved communication between neurons means that electrical signals are more efficiently transmitted throughout the new path. For example, when you try to recognize what kind of bird is singing, new connections are formed between some neurons. So, the neurons of the visual cortex determine the color of the bird, the auditory cortex - its singing, and other neurons - the name of the bird. Thus, in order to identify a bird, you need to repeatedly compare its color, voice, name. With each new attempt, when returning to the neural circuit and restoring neural transmission between the neurons involved in the process, the efficiency of synaptic transmission increases. Thus, the communication between the corresponding neurons is improved, and the process of cognition is faster each time. Synaptic plasticity is the basis of human brain plasticity.

neurogenesis

Given that synaptic plasticity is achieved by improving synapse communication between existing neurons, neurogenesis refers to the birth and reproduction of new neurons in the brain. For a long time, the idea of neuronal regeneration in the adult brain was considered almost heresy. Scientists believed that nerve cells die and do not regenerate. After 1944, and especially in recent years, the existence of neurogenesis was scientifically proven, and today we know what happens when stem cells (a special kind of cells located in the dentate gyrus, the hippocampus, and possibly the prefrontal cortex) divide into two cells: a stem cell and a cell that will turn into a full-fledged neuron, with axons and dendrites. After that, new neurons migrate to different areas (including distant from each other) of the brain, where they are needed, thereby maintaining the neuronal activity of the brain. It is known that both in animals and humans, sudden neuronal death (for example, after a hemorrhage) is a powerful stimulus for triggering the process of neurogenesis.

Functional Compensatory Plasticity

The neuroscience literature has covered the topic of cognitive decline with aging and explained why older people exhibit lower cognitive performance than younger people. Surprisingly, not all older people show poor performance: some perform just as well as younger people. These unexpectedly different results in a subgroup of people of the same age were scientifically investigated, as a result of which it was found that when processing new information, older people with greater cognitive performance use the same areas of the brain as young people, as well as other areas of the brain. , which are not used by either young or other older participants in the experiment. This phenomenon of overuse of the brain by the elderly has been investigated by scientists who concluded that the use of new cognitive resources occurs as part of a compensatory strategy. As a result of aging and a decrease in synaptic plasticity, the brain, demonstrating its plasticity, begins to restructure its neurocognitive networks. Research has shown that the brain arrives at this functional decision by activating other neural pathways, engaging areas in both hemispheres more frequently (which is usually only found in younger people).

Functioning and Behavior: Learning, Experience and Environment

We have considered that plasticity is the ability of the brain to change its biological, chemical and physical characteristics. However, not only the brain is changing - the behavior and functioning of the whole organism is also changing. In recent years, we have learned that genetic or synaptic brain disorders occur as a result of both aging and exposure to a huge number of environmental factors. Especially important are discoveries about the plasticity of the brain, as well as its vulnerability as a result of various disorders. The brain learns throughout our lives - at any time and for various reasons, we acquire new knowledge. For example, children acquire new knowledge in huge quantities, which provokes significant changes in brain structures during moments of intense learning. New knowledge can also be obtained as a result of neurological trauma experienced, for example, as a result of damage or hemorrhage, when the functions of the damaged part of the brain are impaired, and you need to learn anew. There are also people with a thirst for knowledge, for which it is necessary to constantly study. Due to the myriad of circumstances under which new learning may be required, we wonder if the brain changes every time? Researchers believe this is not the case. It appears that the brain acquires new knowledge and demonstrates its potential for plasticity if the new knowledge helps improve behavior. That is, for physiological changes in the brain, it is necessary that the consequences of learning be changes in behavior. In other words, new knowledge must be needed. For example, knowledge about another way to survive. Probably, the degree of usefulness plays a role here. In particular, interactive games help develop brain plasticity. This form of learning has been shown to increase the activity of the prefrontal cortex (PFC). In addition, it is useful to play with positive reinforcement and reward, which is traditionally used in teaching children.

Conditions for the implementation of brain plasticity

When, at what point in life is the brain most susceptible to changes under the influence of environmental factors? Brain plasticity seems to be age-dependent, and there are still many discoveries to be made about the influence of the environment on it depending on the age of the subject. However, we know that the mental activity of both healthy older people and older people with a neurodegenerative disease has a positive effect on neuroplasticity. The important thing is that the brain is subject to both positive and negative changes even before a person is born. Animal studies have shown that when mothers-to-be are surrounded by positive stimuli, babies form more synapses in certain areas of the brain. Conversely, when bright light was turned on during pregnancy, which introduced them into a state of stress, the number of neurons in the prefrontal cortex (PFC) of the fetus decreased. In addition, the PFC appears to be more sensitive to environmental influences than the rest of the brain. The results of these experiments are important in the nature versus environment debate, as they demonstrate that the environment can change neuronal gene expression. How does brain plasticity evolve over time, and what is the result of environmental influences on it? This question is the most important for therapy. Conducted genetic studies of animals have shown that some genes change even as a result of a short exposure, others - as a result of a longer exposure, while there are also genes that could not be influenced in any way, and even if they did, they would still change as a result. returned to their original state. Although the term "plasticity" of the brain carries a positive connotation, in fact, by plasticity we also mean negative changes in the brain associated with dysfunctions and disorders. Cognitive training is very helpful in stimulating positive brain plasticity. With the help of systematic exercises, you can create new neural networks and improve synaptic connections between neurons. However, as we noted earlier, the brain does not learn effectively if learning is not rewarding. Therefore, when learning, it is important to set and achieve your personal goals.

1] Definition taken from: Kolb, B., Mohamed, A., & Gibb, R., Search for factors underlying brain plasticity in normal and damaged states, Revista de Trastornos de la Comunicación (2010), doi: 10.1016/ j.jcomdis.2011.04 0.007 This section is derived from Kolb, B., Mohamed, A., & Gibb, R., Finding the Factors Underlying Brain Plasticity in Normal and Damaged Conditions, Revista de Trastornos de la Comunicación (2010 ), doi: 10.1016/j. jcomdis.2011.04.007