How the brain works. Part 1. What is sleep for?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

How the brain works. Part 2. The brain and alcohol

But, interestingly, we were not told very important things about those processes that actually take place in the human brain and nervous system, which are very important for understanding what and why we are doing, including in the learning process and various workouts.

I hope that if you take a little time to study this article, it will help you to build your life more rationally and effectively and use the capabilities of your body to your advantage.

In the human body, the central and peripheral nervous systems are isolated. The central nervous system includes the brain and back. The peripheral nervous system includes the rest of the neurons that penetrate all human tissues, collecting information about the state of these tissues and transmitting control signals from the central nervous system to them. It is due to the neurons of the peripheral nervous system that we feel pain, which informs us that something is wrong with certain organs.

At the elementary level, the human nervous system is made up of neurons (nerve cells) and accessory neuroglial cells that help neurons perform their functions.

A neuron consists of a cell body (2), or soma, one long little branching process called an axon (4), as well as many (from 1 to 1000) short highly branching processes - dendrites (1). The diagram also shows the cell nucleus (3), axon branches (6), myelin fiber (5), interception (7) and neurilemma (8).

The length of the axon reaches a meter or more, its diameter ranges from hundredths of a micron to 10 microns. The dendrite can be up to 300 µm in length and 5 µm in diameter.

Neurons are connected to each other, forming the so-called neural networks. In this case, the dendrites of neurons, which are the input signal lines, are connected to the axons of other neurons, along which the so-called "nerve impulses" are transmitted from the neuron. The junction of one neuron with another is called "synapse" (from the Greek word "synapt" - to contact). The number of synaptic contacts is not the same on the body and processes of the neuron and is very different in different parts of the nervous system. The body of a neuron is 38% covered with synapses and there are up to 1200-1800 of them on one neuron. All neurons of the central nervous system are connected to each other mainly in one direction: the branching of the axon of one neuron is in contact with the body or dendrites of other neurons.

In neurons from the peripheral nervous system, axons are in contact with the tissues of the organs they control or the cells of the muscle tissue. That is, the impulse transmitted along the axon does not affect other neurons, but causes, for example, muscle cells to contract.

At the same time, I want to especially draw your attention to the fact that in fact what many sources call "nerve impulses" are actually impulses of electric current, which is very well demonstrated in an old school experience, when the muscles on a frog's leg begin contract under the influence of an electric current. That is, the activity of the brain is based on electromagnetic impulses that propagate along a neural network formed by connections between neurons.

Initially, the neuron is in the so-called unexcited state. Through synapses, electrical impulses from other neurons come to it, and when the total number of these impulses reaches a certain threshold value, the neuron goes into an excited state and an electric current pulse runs along its axon, transmitting a signal to other neurons or causing muscle tissue to contract.

Thus, the control of various physiological processes and our thinking occur due to the propagation of electrical impulses in the neural network of the central and peripheral nervous systems.

These impulses do not travel very quickly. The speed of propagation of a pulse through one synapse is measured and amounts to about 3 milliseconds. This means that the maximum signal frequency that you can transmit through such a contact is only about 333 Hz. For us, accustomed to processor frequencies of several gigahertz, the speed of the nerve cells may seem too low, but in fact this idea is greatly mistaken, since the neural network of our brain actually has enormous computing power.

In the summer of 2013, Japanese scientists conducted a simulation of the work of a neural network, which consisted of 1.73 billion neurons, between which 10.4 trillion were installed. synapses (connections). The supercomputer Fujitsu K computer was used for simulation, which in November 2013 ranked 4th in the world in terms of overall performance.

So to simulate one second of the operation of this neural network in a supercomputer with 705,024 cores and consuming 12.6 kW of electricity took as much as 40 minutes! It is believed that the average human brain contains about 86 billion neurons. This is about 50 times larger than the simulated neural network. At the same time, the time difference was 2400 times (so many seconds in 40 minutes). The total difference in speed is about 120,000 times. Add to this also the volume that this supercomputer occupies, as well as the amount of energy that was spent on these calculations.

In other words, our computers are still very far from the efficiency and speed that are implemented by Nature in our brain!

But let's return to the consideration of what processes occur in our brain and the entire nervous system as a whole. There are three important components that make it work. The first one, which I have already mentioned, is the propagation of electrical impulses along the neural network. This, if I may say so, is the main computational process that happens all the time. And it is he who determines our mental activity and motor activity. The second process is based on the action of the so-called neurotransmitters, which form the chemical level of regulation of nervous activity. Depending on what neurotransmitters are secreted by the body, the speed of neurons and the entire nervous network can either increase, especially in critical situations, or, conversely, decrease when the state of overexcitation is required to be extinguished and calm down, since the work of neurons in an accelerated overexcited state leads to them premature destruction and withering away. But about the third important component in the medical literature, you will find practically nothing! Given that this third component is just one of the most important, since it is it that determines the quality of the entire neural network, its functionality. This most important component is the structure of connections that is formed between neurons, since it is this structure that determines how and what processes occur in this neural network during its operation.

The main feature of the neural network that our neurons form is that it is not constant. Neurons have the ability to rebuild connections among themselves, changing the structure of the neural network. And this is one of its fundamental differences from our modern computers, which basically have a fixed structure of computational modules.

The uniqueness of our nervous system lies in the fact that it constantly changes its structure, optimizing it for solving certain problems. At the same time, the formation of connections between neurons, including in the brain, begins long before the birth of a child. Determination of fetal cells, in which it is already possible to isolate those cells from which the frontal lobes of the brain will be formed in the future, is observed already on the 25th day after conception. At a period of 100 days, the main parts of the brain have already been formed and its structure begins to form.

This means that from that moment on, everything that happens around the child in the womb will influence the structure of the neural network that will eventually be formed! In other words, the abilities and capabilities of the unborn child begin to take shape long before his birth. That is why pregnant girls and women need to create more comfortable conditions almost immediately after conception, and not at 6-7 months. Moreover, they are comfortable not so much in the physical sense as in the psychological one, since all the emotional experiences of the mother are ultimately transmitted to the unborn child.

The active process of forming connections between neurons, that is, programming the neural network, continues after birth. In fact, it is precisely in the formation of the necessary connections and optimization of their structure that the meaning of learning consists. A newly born child does not really know how to control his body. And not only because his bones and muscles have not yet strengthened, but also because the connections necessary for controlling movements have not been formed in the nervous system. Built-in programs are available only to ensure the activity of the main organs and systems, such as the heart, lungs, liver, kidneys, etc. This is formed at the stage of fetal development in the womb according to the programs that are written in the DNA. But everything that is associated with motor activity is acquired after birth in the learning process.

The first movements, for example when a child learns to walk, are done under the complete control of the brain, and therefore they occur slowly. Including because the impulses through synapses propagate rather slowly, as mentioned above, about 3 ms per connection. If the brain is involved in this process, then the number of connections that are involved in information processing, decision-making and transmission of a control signal to muscles will amount to tens and hundreds. But when a child repeats certain movements many times, neurons in his nervous system will gradually form new connections, due to which the time for completing frequently repeated tasks will be significantly reduced. And at some point, the brain will be excluded from the processing of this movement and it begins to occur reflexively, that is, only due to those impulses that pass through the peripheral nervous system. From this moment on, a person only needs to think about what he wants to do, and how to do it, the body, more precisely, the peripheral nervous system already knows itself. A corresponding program is already stitched into it, which implements the required movement, which is often quite complex.

Remember how you once learned some new complex movements, such as cycling, skiing or skiing, or the same swimming. In the beginning, you didn't really succeed. With the help of your consciousness you had to control all your movements, where to turn the handlebars of the bicycle or how to put your feet in order to brake on skis. But if you were persistent, then after a while you started to get better and better, and at some point you suddenly started to just ride a bike without thinking about where to turn the steering wheel so as not to fall or start chasing with a stick for a puck, not thinking about how to put the skates correctly in order to turn and not fall. In your nervous system, the necessary neural connections have been formed, which unloaded your brain, and your body has acquired the appropriate skills.

In fact, one of the meanings of training when doing any kind of sport is precisely in the formation of the necessary skills, that is, in the creation and subsequent optimization of connections between neurons, which provide the most optimal movements for a given sport. What is commonly referred to as sports technique. Moreover, the earlier a person begins to engage in this or that sport, the easier it is for his nervous system to form the necessary connections, since it is not yet filled with programs, as in an adult. That is why there is now a tendency that the earlier a child begins to engage in a particular sport, the more chances he has to achieve outstanding results. To this it must also be added that when engaging in one or another activity, the nervous system will not only rebuild its neural connections, but will also trigger the processes of adaptation of the whole organism to these conditions.

The process of forming connections and optimizing the structure of the neural network occurs not only for performing movements, but in general for any activity that the nervous system and our brain carry out. If you do mathematics and solve a lot of problems, then you will also develop the appropriate skills, your neural network will rebuild and from some time you will solve problems faster than others. Often you will even know the answer only by looking at the condition of the problem, before you really have time to substantiate it analytically (this was verified by me on personal experience). Similarly, the formation of skills, that is, the necessary connections in the neural network, occurs when playing music, and when teaching drawing, and in general during any activity. Learning something, we constantly program ourselves, changing the connections between neurons.

If we draw an analogy with modern computers, then at the beginning we solve any problem programmatically, using the resources of the brain, and if this or that task is repeated often enough, then the corresponding program is transferred to the hardware level, which dramatically reduces the time of its execution.

At the same time, the restructuring of connections between neurons does not occur at any time. Since this process is not very fast, in order to rebuild the connections between neurons, we need regular sleep. And this is precisely the main function of sleep, which you will not read about in any textbook or book on medicine!

The information that our brain perceives during wakefulness is received and stored in the form of a set of electrical impulses that propagate in the environment of the neurons of the brain. This is, so to speak, our RAM. And although the number of neurons in the brain is very large, our operative memory is still quite limited and it must be periodically cleared. It is this process that actually occurs during sleep. There is a misconception that there are two phases of sleep, slow and fast. This is not entirely true. According to recent studies, there are four phases of slow wave sleep and one phase of the so-called REM sleep. These phases were named "slow" and "fast" because of the frequency of the main brain waves that are recorded in the cerebral cortex during a particular sleep phase.

The general essence of the processes occurring during sleep is as follows. After falling asleep, the primary analysis of the information accumulated during the day takes place, during which a decision is made which information needs to be stored for a long time, which information needs to be kept for a while, and which information can be forgotten as insignificant. The information that we decided to save for some time will remain in the "random access memory", that is, in the form of a set of impulses that propagate between neurons. The information that it was decided to forget is simply erased, and the corresponding neurons are released and go into standby mode. And with the information that it was decided to keep in long-term memory as important, further work begins.

In the next phase, a plan is drawn up for restructuring the connections between neurons in order to remember the necessary information or skills. Moreover, if information is memorized in the cerebral cortex, the skills are transferred to the level of the spinal cord or even the peripheral nervous system, where new connections between neurons will be formed. When the adjustment program is ready, the so-called "fourth phase" or deep slow delta sleep begins. It is at this moment that some connections between neurons are destroyed, while others are formed. That is, programs that have become unnecessary or contain errors can be erased or corrected, and the necessary new ones will be additionally added.

It is precisely the fact that during this phase the neural network is in a state of deep restructuring of connections that explains the fact that it is very difficult to wake a person up during delta sleep. And if this succeeds, then he will feel bad, not sleeping enough, absent-minded, with lowered indicators of brain activity. At the same time, to come to a normal state, he still needs to sleep from five to fifteen minutes. After that, he already wakes up completely and at the same time feels very vigorous and slept. Why? Yes, because when he was awakened, some of the connections were not yet formed, so the neural network could not function normally. And when he slept a little more, the process of forming connections was completed and the nervous system was able to switch to normal operation.

Such cycles of analysis, the formation of a program for restructuring connections and their actual restructuring during sleep are repeated cyclically 4-5 times. Accordingly, a person can be woken up relatively easily and without special consequences for him during the stage of analysis and preparation of the program, but it is undesirable to wake him up during the phase of restructuring of connections.

But REM sleep serves other purposes. It is during this phase that we see the most vivid and colorful dreams. This phase is needed to analyze the accumulated information or solve those tasks for which we do not have enough resources during wakefulness, including for modeling various situations, including predicting the possible development of events in the future. That is why we have a saying in Russia: "the morning is wiser than the evening."

The fact is that during wakefulness, most of the resources of the nervous system are spent on processing signals from our senses. We spend up to 80% only on the analysis of visual information. That is why many people, when they are busy solving a complex problem, pondering some important problem, or trying to remember the information they need, close their eyes for a while. This allows them to direct part of the resources of the nervous system to the solution of this problem. During sleep, our senses are in a passive state, reacting only to the strongest stimuli, which allows us to free up the main part of the brain to analyze the available information and solve important problems for us. That is why there are many stories about "prophetic dreams" and that it was in a dream that a person remembered where he put that thing that he could not find during the day, or that in a dream he finally managed to solve this or that a task that he had struggled with unsuccessfully during the day. One of the most famous stories on this topic is how Dmitry Ivanovich Mendeleev saw exactly in a dream how the periodic system of chemical elements should look like (and which, by the way, we are now depicted in a completely different distorted form).

In prophetic dreams, in which a person sees certain events that then occur in reality, in fact, there is also no mysticism. The fact that the future can be predicted within certain limits is in fact an obvious fact. Almost everyone who drives a car is forced to constantly predict the future based on the information about the world around him that he perceives through his senses, as well as his previous experience that he has accumulated and stored in the form of neural connections in the cortex of his brain. It is impossible to drive a car without getting into an accident if you cannot predict what will happen on the road at the next moment in time. Will another car appear at the intersection across your path or not? After all, quite a long time passes from the moment you press the pedal until your car passes the intersection. That is, when approaching an intersection, your brain, through the senses, primarily vision, collects information about the behavior of surrounding objects, analyzes it and predicts the future, that is, where they will be at the moment when your car will be in a few seconds at the crossroads.

If your brain is mistaken or received incomplete information, then the prediction will be erroneous, which can lead to an accident or only an emergency if the predictions of the brain of the driver of another car turn out to be better than yours, because he was more attentive or more experienced, which allowed him to avoid a collision. And the fact that while driving, the driver should not be distracted by anything, including talking on a cell phone, is explained precisely by the fact that any additional thought process somehow takes over part of the brain's resources, which means that it starts to get worse. perceive incoming information or makes lower-quality predictions of the future.

We also regularly make predictions for a longer period, albeit simpler ones, which are often called "planning". If you planned everything well and took into account all the factors that can affect the result, then with a very high probability the planned event will occur.

In fact, there is nothing surprising in prophetic dreams. We constantly receive information about the world around us, including information that we simply do not have time to fully analyze during the day. But in a dream, when the main part of the brain's resources is just aimed at analyzing the collected information, our consciousness can make a deep qualitative analysis and form a higher-quality prediction, which we will see in a dream as “prophetic”.

But we see dreams, especially prophetic ones, we do not always. REM sleep occurs only after at least one complete NREM sleep cycle. In order for the brain to start analyzing the collected information and forming dreams, it must at least partially free itself of the information accumulated during the day. At the same time, it was experimentally established that the further, the longer the duration of the REM sleep phase becomes. And this is completely logical, since the more cycles of transfer of information from operational memory to long-term memory managed to go through, the more resources the brain has freed up to process information and form dreams. But if you don't get enough sleep, your brain will gradually overflow, not having time to completely clear out during too short sleep. In this case, you either will not have REM sleep phases at all, or they will be very short, while you will not remember those dreams that will arise at this time, since your memory has not yet freed itself from the accumulated information. In other words, if you cannot see or cannot remember your dreams, then this means that you are not sleeping enough and your brain does not have time to recover.

Imagine that the brain is a vessel, and the information received during the day is water, which we gradually pour into this vessel. Processing during sleep of the information accumulated during the day is similar to the emptying of this vessel from the water accumulated during the day. Well, then we get a puzzle known to us from school about how much water flows into the vessel, and how much flows out. If the total capacity of the vessel is 5 liters and you pour in 1.5 liters of water every day, and only 1 liter will pour out during a short nap, then every day you will have 0.5 liters of water. Accordingly, on the eighth day, your vessel will be filled with 4 liters and you simply cannot pour the next one and a half liters of water into it. The rest of the water simply will not fit into the vessel, but will spill past it. And if nothing is changed, then this overflow process can continue for a long time. Until you increase the time for draining the water, draining all the excess accumulated water, that is, you do not get enough sleep, allowing your brain to finally clean up the Augean stables of excess accumulated information.

It is believed that it takes about 8 hours for a person to sleep. This figure is very approximate, since in practice it depends on the nature of the activity that a person is engaged in during the day. If this activity is associated with repetitive physical activity, in which the accumulation of information is slower, then it may take less time to sleep. If a person is engaged in active mental activity, then he may need more than 8 hours. But if you do not get enough sleep on a regular basis, then your intellectual capabilities will gradually deteriorate. It will be more difficult for you to perceive and remember information, you will solve problems worse, your attention will be more distracted.

In general, the average person can be without sleep for 3-4 days. The record for the maximum stay without sleep, without the use of stimulants of any kind, was set in 1965 by American schoolboy Randy Gardner from San Diego, California, who stayed awake for 264.3 hours (eleven days). However, some sources even say that prolonged sleep deprivation has very little effect. But if you raise a more detailed account of this experiment, it turns out that this is far from the case. Lt. Col. John Ross, who monitored Gardner's health, reported significant changes in mental ability and behavior during sleep deprivation, including depression, problems with concentration and short-term memory, paranoia, and hallucinations. On the fourth day, Gardner pictured himself as Paul Lowy playing at the Rose Bowl and mistook the street sign for a man. On the last day, when asked to subtract 7 from 100 consecutively, he settled on 65. When asked why he stopped the account, he stated that he had forgotten what he was doing now.

Thus, one of the useful recommendations that can be given in the light of the above information is that if you cannot, for some reason, constantly sleep the time you need, then it is advisable to get a good night's sleep at least once a week in order to give your body time to compensate for the lack of sleep that you have accumulated. At the same time, the indicator that you have enough sleep will not be waking up by the alarm, but waking up when this happens naturally and you feel that you have finally gotten enough sleep. If this requires 12 hours of sleep, then you need to sleep 12 hours.

But for the normal restoration of brain resources during sleep, not only time is needed, but also energy. Our brain consumes a lot of energy. Making up only 5% of body weight, depending on the type of activity, the brain consumes from 30% to 50% of the energy received by the body. In this case, the brain receives most of the energy due to the process of glucose catabolism, that is, the slow oxidation of glucose to CO2 and H2O (carbon dioxide and water). We get glucose from food, which is transported by the blood stream to the cells of the brain. But glucose alone is not enough for this process; for the oxidation of each molecule of glucose C6H12O6, 6 more molecules of oxygen O2 are needed, which we constantly receive from the surrounding air during respiration. This means that if you want to get a good night's sleep or are actively involved in mental activity, the area where you are located must be sufficiently well ventilated. Otherwise, if there is a lack of oxygen in the air or, which happens much more often, an excess of carbon dioxide, your brain will not receive enough energy for all the processes taking place in it. So even if you sleep for 8 or even 10 hours in a poorly ventilated room, this will not be enough to get a good night's sleep, which I have repeatedly verified from personal experience. For the same reason, it is recommended to provide ventilation of the room where you are engaged in active mental activity, including where training is taking place. Probably many of you have noticed that when a lot of people gather in a small room, for example, to listen to some kind of report or lecture, then after a while people start to fall asleep. This is precisely because, due to the accumulation of a large number of people in the room, the concentration of carbon dioxide has sharply increased and that reduces the flow of oxygen into the blood and our brain goes into an energy-saving mode, reducing its activity and ceasing to perceive information, especially if the lecture is boring. That is, it does about the same thing as the laptop processor, which slows down when switching to battery power. And in order to maintain attention, we need to make additional efforts in such a situation, preventing ourselves from falling asleep.

In light of the widespread fashion for the installation of plastic windows, which undoubtedly insulate the premises from the street much better, the problem of ventilation of premises becomes even more urgent, since the existing natural ventilation system in buildings does not always cope with it, and often does not work at all, since the neighbors are higher floor during the next European-style renovation they managed to fill up your ventilation duct with garbage. So if you want to get a good night's sleep, especially if you don't have enough sleep time, then take special care to ensure that your sleeping area is well ventilated. It is better to slightly open your plastic window, but at the same time turn on the heater, than to sleep with tightly battened windows in a poorly ventilated room. For the same reason, in sleeping rooms, it is advisable to install plastic windows with a micro-ventilation system, which allow this window to be slightly opened, or purchase and install additional external special devices on your window that allow you to do the same if you already have such a window without such a system.

Sleep has another important function that most people know little about. Recent studies have shown that people with sleep deprivation experience not only a decrease in the quality of the brain, but also a decrease in immunity. This happens because it is during sleep that the processes of regeneration and restoration of damaged tissues are launched, as well as the formation of the necessary antibodies to fight viruses and bacteria. All these processes involve the spinal cord and peripheral nervous systems. During wakefulness, they are loaded with the provision of human motor activity, and during sleep, their resources are released and can be used to analyze what, where and how should be repaired in the body. That is why when we are sick, we want to lie down and sleep. For the same reason, if you do not get enough sleep, then you will get sick more often, and your body will age and deteriorate faster.

A separate topic is the use of various neurostimulants, especially all sorts of energy drinks, which, as the advertisement assures, can reduce sleep time and stay vigorous and cheerful for a long time. This is true for short periods of time. With the help of chemical action, you can make your brain work actively for a few more hours. But at the same time, you need to understand that this is far from free.

First, the use of neurostimulants, be it tea, coffee, or more aggressive energy drinks, does not actually increase the capacity of your brain, its working memory, that hypothetical vessel into which we can pour water from the information around us. They only allow you to pour 2 liters at a time instead of 1.5 liters. But this means that your vessel will overflow much faster. Therefore, a critical state of overflow, after which the brain ceases to function normally, occurs much faster, after which no neurostimulants will really help you. Accordingly, after such an extreme mode of work, your brain will need a longer rest (more water needs to be drained).

Secondly, all neurostimulators transfer neurons to the extreme or even transcendental mode of operation, which sharply reduces their lifespan. The very popular myth that neurons in the body do not regenerate has long been disproved. It arose because neurons are the longest-lived cells in the body, because replacing them as part of a neural network is not an easy task, so the body is trying to delay this process as late as possible. For the same reason, new neurons appear much slower than normal cells. So in this case, the question is not that new neurons do not appear in the body at all, but in the balance between the death of existing and the emergence of new nerve cells. If neurons die faster than the body produces new ones, then a process of degradation of the nervous system and consciousness occurs. And if you start to abuse the same energetics, then by doing so you increase the rate of neuronal death, making this balance negative.

A similar, but much stronger effect occurs with the use of various drugs, especially alcohol. I will talk about how alcohol affects the body and the nervous system in the next part.

Dmitry Mylnikov