How many calories does the brain burn per day. How to control the energy of the brain
This post is for those who fall into melancholy and despondency at the thought of the gym or jogging, most of all they like to sit at the computer, and at the same time want to lose a few kilograms. Of course, nothing comes just like that, and in order to lose weight without getting up from your favorite computer chair, you have to do something, namely, think.
Scientists from a Canadian university conducted experiments on students, measuring the number of calories that the brain consumes. Three groups of students received different tasks that had to be done for 1.5 hours. One group did nothing, the second - memorized texts from paper, the third - worked at the computer. As a result, the group memorizing texts from books burned 200 kcal more than idle students, and those who worked at the computer burned as much as 250 kcal more.
Scientists have found that the brain consumes the most calories during concentration. During the maximum concentration for 20 minutes, the brain is able to “eat” such an amount of energy that it would not have spent for the whole day spent without mental activity. Therefore, it can be quite difficult to focus on anything for more than 20-25 minutes - the body is simply forced to conserve energy reserves.
How many calories can you burn by actively thinking?
With absence mental stress, the brain burns up to 400-500 kcal per day, and during vigorous activity his costs are doubled. It is generally accepted that when a person strains the brain, he spends 1.5 kcal per minute, that is, 90 kcal per hour, and if the activity is unusual, his costs increase even more.
Another feature - emotional experiences increase energy consumption by 10-20%, and intellectual activity, accompanied by emotions, by 30-40%. Scientists from the Research Institute of Physiology. PC. Anokhin conducted another experiment, during which the energy consumption of students during exams was measured. It turned out that three days before the exams, the student consumed 750 kcal for intellectual activity, and during the exam - 1000-1100 kcal.
So, given all of the above, fans seated image life can be advised as follows:
Think more
Viewing publics in social networks, funny correspondence with friends or toys (except for those genres where you need to turn on the brain) will not waste extra calories. To lose weight at the computer, you need to perform some kind of intellectual activity, for example, read difficult to understand, interesting articles and books, solve some problems, solve crossword puzzles. At the same time, it is desirable not to be distracted, to maintain concentration on the subject longer.
The longer you concentrate, the more calories you burn.
Move food away from the computer
During mental activity in the body, the level of glucose, a substance that feeds on brain cells, drops sharply. To make up for losses after mental activity, a person really wants to eat. This does not mean at all that the body really needs additional calories, it just needs glucose.
Scientists believe that a cup of sweet tea will be enough to make up for losses and give the brain the necessary nourishment, so after your intellectual exercises, do not rush to eat chocolates or cook dumplings - sweet tea, and the feeling of hunger will let go.
emotional experiences
Of course, you can’t give yourself strenuous exams every day, but you can still do something. For example, solve logic puzzles for a while or play chess with someone. So to intellectual activity adds an element of excitement. More excitement, more emotions, more calories burned.
Something new
More energy is consumed by the part of the brain that is in work, so energy consumption can be increased by alternately turning on different departments of the brain, that is, by solving multi-part tests or playing puzzle games.
Besides, the brain consumes more energy solving non-standard tasks. If you are a humanist, try to solve logical tasks, remember school course geometry or algebra. In general, engage in new types of intellectual activity - it not only increases energy consumption, but also helps to develop the brain.
And finally, it is impossible not to mention that simple walking burns 4 kcal per minute, so if you are tired of thinking, go for a walk.
If children grow up like weeds (dandelions are weeds, after all), then their brains will burn like a torch. It is quite expensive to maintain the brain of an adult, which uses 17% of the total energy of the body, although it is only 3% of body weight, but this is nothing compared to the energy costs for development. child brain. The brain almost reaches full capacity at age 7, but it still contains connections that will be removed later as life experience the child will contribute to his development.
Synapses consume most of the brain's energy, so maintaining additional connections is not cheap. From 3 to 8 years old, children's brain tissue consumes twice as much energy as adult brain tissue. A five-year-old child who weighs 20 kg needs 860 calories per day, and half of this energy goes to the brain.
Researchers are studying the brain's energy use using positron emission tomography (PET), which measures the level of radiolabeled glucose, the sugar that is the main "fuel" for neurons (see figure). Radio markers are created by adding radioactive atoms, which allows you to track the movement chemical in the depths of the human brain or body.
In the first 5 weeks after birth, the highest energy consumption is observed in the somatosensory and motor cortex, thalamus, brain stem and the cerebellum, i.e. in the most mature parts of the brain at birth, which are responsible for basic life functions such as breathing, movement and touch.
At 2-3 months of age, energy intake increases with temporal, frontal and occipital lobes cerebral cortex, as well as in subcortical basal ganglia, which, among other things, control vision, spatial orientation, and movement.
Between 6 and 12 months of age, energy intake increases in frontal lobes cerebral cortex, when children first begin to control their behavior.
The amount of energy consumed by the brain continues to increase until the age of 4 years, and at the age of 9 years begins to decline, consistently reaching "adult" levels in different areas as they mature. This process is completed between the ages of 16 and 18.
Because the nerve connections develop on different stages growing up, there are several sensitive periods, each of which corresponds to a certain function of the brain. Sensitive periods are especially characteristic for developing brain babies and toddlers as it grows very fast, but they can occur at other times as well. Some sensitive periods begin and end before birth, such as the development of the sense of touch based on the sensations of the baby in the womb (see Chapter 11). Many occur shortly after birth, for example, the first interaction with loved ones forms brain connections that respond to stress (see Chapter 26). Other sensitive periods, such as learning the grammatical aspects of a language, continue until the end of childhood and into adolescence.
As we described in Chapter 2, programmed chemical signals guide axons to target sites and cause a large number of synapses to form. After creating these basic elements, life experience can influence further development by controlling the activity of axons and synapses. Synapses of neurons that are more often activated, with more likely will be maintained and strengthened by the plasticity of biochemical pathways to the target cell, while broken synapses (i.e. connections between two neurons) weaken or disappear. Synaptic activity can also cause growth or retraction of axonal or dendritic branches. Cells that are activated together bind strongly to each other (see chapter 21).
After completing these plastic changes brain architecture is less amenable to modification in the future, either because extra axons and synapses are no longer available or because the biochemical pathways that determine synapse activity change with age. In this regard, the brain uses sensory experience to form connections in the neural circuitry, cutting off unnecessary connections and maintaining the strongest and most active to maintain perceptual and behavioral patterns appropriate to the child's individual environment.
Unnecessary synaptic connections are removed during childhood. Thus, the total number of synapses in the primary visual cortex of the brain increases rapidly from birth to a climax at 8 months of age, and then gradually decreases up to 5 years as visual abilities develop (see Chapter 10). The maximum decrease in the number of synapses in this region of the brain occurs between the ages of 5 and 11 years (we do not know exactly when, since children from 6 to 10 years old were not examined). In the frontal cortex, synapse density remains high until at least age 7, decreases slightly by age 12, and reaches adult levels by age 14–15 (see Chapter 9). It is not entirely clear what happens between the ages of 7 and 12.
The process of synapse elimination has been studied in much greater detail in other primates, and the results are generally consistent with the fragmentary data from human studies. In rhesus monkeys, the explosive growth of synapses in the first few months after birth is followed by a gradual and then accelerating decline in their number during childhood. The adult level of synapse density is observed after reaching puberty. Although this increase in animals follows similar trends, the decrease follows different schedules in different individuals, reinforcing the idea that it is events in environment influence the process of elimination of synapses.
In all areas of the cerebral cortex studied in monkeys, the development of synapses follows a similar time schedule. It is still unclear whether this principle of simultaneous development of synapses can be applied to children. Developmental brain scan gray matter , where all the synapses are located, shows that frontal lobes reach their final volume somewhat later than the visual areas of the cerebral cortex (They are located in the occipital lobes. - Note. ed.). However, due to the age gap in counting human synapses and discrepancies between individuals, the evidence to support this position is incomplete. In any case, measurements of brain energy in children show that there is relatively little difference in the developmental timing of different regions of the cortex, and that elimination of synapses continues throughout childhood (see sidebar above: "Did you know? Your child's brain consumes half of the body's energy") .
To understand how experience affects synaptic changes during the sensitive period, we must turn to animal studies. Barn owls hunt in the dark and must pinpoint the source of a sound in order to know the position of their prey. They do this by comparing the difference in arrival time sound signal between the left and right ear, since the sound coming from the left reaches the left ear before the right, and vice versa. A more complex calculation of the upper or lower position sound source is carried out according to the differences in loudness created by the shape auricle. The owl's brain takes in information about time discrepancies and volume differences and uses it to create a brain map of the sound source. Because the input depends on individual characteristics such as head size and ear shape, which change as the animal grows, it cannot be determined in advance, so natural mapping occurs during development.
Perception is not passive even in small children. Your child's brain has certain preferences about what it should learn at different stages of development.
To "calibrate" the auditory map, the owl's brain additionally processes visual information. During the experiment, the researchers provided the owls with prismatic glasses that visually shifted objects to one side. At first, trying to move around with glasses on, the birds make a lot of mistakes, but gradually the brain adapts to the distorting glasses, shifting its visual map to reflect new reality. The sound space map also shifts as a result of the response to the prism glasses, although the auditory information remains unchanged.
This shift occurs because the neurons receiving the time and volume information extend their axons and connect with new neurons in another part of the map. The old connections remain in place, although their synapses weaken, allowing the owls to revert to the old scheme of things after their glasses are removed. This perceptual plasticity takes place during the sensitive period, up to about 7 months. Adults whose sensitive period is over have a much harder time rewiring, because their axons are limited to a smaller area of the brain and the neural circuit can no longer carry signals beyond the range set in youth.
All our organs burn calories when they perform their functions, right? So, since the brain is an organ, thinking burns calories, and increased thinking burns more calories?
Remember, in cartoons, when the hero thinks a large number of does steam come out of his ears? Okay, a bit of an exaggeration, but there's a serious shake-up that really happens when we make a mental effort. The brain burns a lot of calories at rest, and outward signs we can easily conclude that concentration promotes the use of energy for potential actions. The reality, however, is more complex, and, in my opinion, much more interesting.
Our brain makes up only 2 percent of our total body weight, but consumes roughly 20 percent of our total calorie intake. The percentage is even higher in children whose brains are still developing. The brain of an average newborn uses about 75 percent of the available energy, an 11-year-old one third, and an adult, if converted into units of energy,- about 20 watts.
About 60 to 80 percent of the brain's energy is used for "neural signaling" - I think that's what ordinary people who dedicate their lives to repair and replenishment call it. Just like any physical matter, the brain "burns" glucose, which interacts with oxygen to produce "fuel". Glucose and oxygen are carried in the blood, so during strenuous mental activity we can experience an increase in cerebral blood flow and an increase in the use of glucose and oxygen, and as a result, more energy consumption.
And here is what scientists found in the course of their research:
In 1878, an Italian scientist working on a patient with a skull fracture discovered that the brain pulsed faster when the subject was solving arithmetic problems.
In a 1995 study, glucose intake and cerebral blood flow of volunteers who underwent a card sorting test increased by 12 percent.
A 1987 study that required volunteers to think about afternoon walk, increased their brain metabolism by 10 percent.
A 1992 study of Tetris players showed that if they played the game 5 days a week for a month or two, their brain's consumption of glucose increased significantly, suggesting that their thinking became more efficient with practice.
However, upon closer examination, not everything is simple. For example, back to the card sorting test, while cerebral blood flow and glucose uptake increased, oxygen use — no, this means that there was no increase in combustion - the brain did not "burn" noticeably more"fuel". This is what neuroscientists are still trying to figure out. cerebral blood flow does not increase so rapidly to provide an immediate increase in energy consumption; researchers now suggest that the rate of blood flow increases to cool the brain or carry away waste products. Glucose breakdown increases, but without combustion (oxidation), the energy jump is small, perhaps less than 1 percent.
However, the fact remains that the brain consumes a disproportionate amount of energy, most of which is spent thinking. That said, some brain scientists say we should take a different view of what's going on there. Previously, it was believed that the brain is extremely passive in responding to external stimuli. Now that we understand that external events do not affect the change in the brain's energy consumption as much, a different picture emerges: most of our mental activity takes place strictly in our heads.
"So what", - you say. Give me a sec. Neurologist Marcus Rachel, writing for the journal Science, calls the brain "a Bayesian inference engine designed to make predictions about the future." In other words, the brain itself creates the memories, conclusions and desires that make up our personality. All this energy goes into feeding a team of "pipe-smoking dwarfs" between our ears, who take in all our feelings, process them, and organize our next steps.
And these dwarfs work quite effectively. The human brain contains approximately 86 billion neurons, occupying a volume commensurate with a grapefruit (gorillas and orangutans, the closest primate brains to us, have about 33 billion). The world's most powerful electronic brain is currently a supercomputer titan, located at the Oak Ridge National Laboratory in Tennessee, which can perform 17.6 quadrillion floating point operations per second, or 17.6 petaflops. Bearing in mind that the mind and computers are not exactly comparable, it is believed that the processing power of the human brain is 1 exaflop (57 times that of a computer).
Of course, in terms of pure computing power, machines will undoubtedly surpass humans, some believe within a decade. But let's take this to the future. Remember, the adult brain uses approximately 20 watts, which means that its performance is approximately 50 petaflops per watt. The performance of a conventional supercomputer is 2.5 gigaflops per watt. That's 1/20 millionth of the efficiency of the brain. In other words, supercomputer Titan – 8.2. a mega watt liquid-cooled monster the size of a large suburban home. A more powerful human model powered by Cheerios cereal can fit in a hat.
1. The brain, like muscles, the more you train it, the more it grows. The brain of an average adult male weighs 1424 g, with old age the mass of the brain decreases to 1395. The largest female brain in weight is 1565. The record weight of the male brain is 2049. The brain of I. S. Turgenev weighed 2012. The brain evolves: in 1860 year average weight of the male brain was 1372 g. The smallest weight of a normal non-atrophied brain belonged to a 31-year-old woman - 1096 g. Walnut and weighing only 70 g.
2. The most rapid development of the brain occurs between the ages of 2 and 11 years.
3. Regular prayer reduces the frequency of breathing and normalizes the wave vibrations of the brain, contributing to the process of self-healing of the body. Believers go to the doctor 36% less often than the rest.
4. The more educated a person is, the less likely they are to have brain diseases. Intellectual activity causes the production of additional tissue to compensate for the diseased.
5. Engaging in unfamiliar activities is the best way to develop the brain. Associating with those who are superior to you in intelligence is also potent agent brain development.
6. Signals in nervous system people reach a speed of 288 km / h. By old age, the speed decreases by 15 percent.
7. The largest brain donor in the world is the monastic order of sister teachers in Mankato, Minnesota. The nuns donated about 700 brain units to science in their posthumous wills.
8. Most high level intellectual development(IQ) was demonstrated by Marilyn Much Vos Savant of Missouri, who at the age of ten already had an average IQ for a 23-year-old. She managed to pass the most difficult test for entry into the privileged Mega Society, which includes only about three dozen people with such high rate IQ, which is found in only 1 person in a million.
9. The highest average national IQ in the world for the Japanese is 111. Ten percent of Japanese have a score above 130.
10. Super-photographic memory belongs to Creighton Carvello, who is able to memorize the sequence of cards at once in six separate decks (312 pieces) at a glance. Usually in our life we use 5-7 percent of the capacity of the brain. It is difficult to imagine how much a person would have done and discovered if he had used at least the same amount more. Why do we need such a margin of safety, scientists have not yet figured out.
11. Mental work does not tire the brain. It was found that the composition of the blood flowing through the brain is unchanged during its vigorous activity, no matter how long it lasts. At the same time, the blood taken from the vein of a person who has worked all day contains a certain percentage of “fatigue toxins”. Psychiatrists have established that the feeling of brain fatigue is determined by our mental and emotional state.
12. Prayer has a beneficial effect on brain activity. During prayer, the perception of information by a person goes bypassing thought processes and analysis, i.e. the person escapes from reality. In this state (as in meditation) delta waves occur in the brain, which are usually recorded in infants in the first six months of his life. Perhaps it is this fact that affects the fact that people who regularly perform religious rites get sick less often and recover faster.
13. For full-fledged work the brain needs to drink enough liquids. The brain, like our entire body, is approximately 75% water. Therefore, to keep it in a healthy and working condition, you need to drink the amount of water your body needs. Those who are trying to lose weight with the help of pills and tea that expel water from the body should be prepared for the fact that along with weight loss they will also lose their brain performance. Therefore, they should do as expected - take any pills prescribed by a doctor.
14. The brain wakes up longer than the body. Intellectual abilities person immediately after waking up is lower than after sleepless night or in a state of moderate intoxication. It is very useful, in addition to morning jogging and breakfast, which enhance the metabolic processes occurring in your body, to do a little warm-up of the brain. This means that you should not turn on the TV in the morning, but rather read something a little or solve a crossword puzzle.
15. It is easier for the brain to understand the speech of men than women. Male and female voices act on different areas brain. Women's voices- more musical, sound at higher frequencies, while the frequency range is wider than that of male voices. to the human brain one has to "decipher" the meaning of what the woman says, using her additional resources. By the way, people suffering from auditory hallucinations are more likely to hear male speech.
16. The brain consumes more energy than all other organs. It ranges from total mass body only 2%, but takes about 20% of the energy produced by the body. Energy supports normal functioning brain and is transmitted by neurons to create nerve impulses.
17. The brain contains approximately 100 billion neurons (cells that generate and transmit nerve impulses), which is about 16 times more than people on Earth. Each of them is connected to another 10,000 other neurons. By transmitting nerve impulses, neurons ensure the continuous functioning of the brain.
18. People only use 10% of their brains. It is a myth. Even though not all the secrets and possibilities of the brain have been revealed, it is silly to say this - the brain always uses as many resources as it needs at the moment. To say that we use the brain by 10% is the same as saying that we use the capabilities of the radio by one percent - we listen to only one wave, but there are still a hundred of them in the range.
19. Every minute, 750 milliliters of blood passes through the brain, which is 15-20 percent of the total blood flow.
20. The brain consumes 25 watts of energy while awake. This amount is enough for a small light bulb.
June 3, 2010 at 23:30How the brain actually works
- GTD
On Habré, articles about various techniques increasing efficiency, improving memory, self-motivation, etc. and so on. Alas, often the authors of these articles have absolutely no idea what the brain is, how it works, and why everything works the way it does.
First of all, you need to understand this:
Thinking is expensive
The information presented below is drawn, for the most part, from S. V. Savelyev's book "The Origin of the Brain", which I highly recommend reading, along with the works of Richard Dawkins and Konrad Lorenz.
The brain emerged as a result of evolution as a flexible, versatile and fast solver. Possession of a brain makes the animal much more adaptable, especially in extreme situations. However, you have to pay for everything: the brain is an extremely costly organ. In humans, an intensively working brain consumes a quarter (!) of the resources of the entire organism. The problem is that the brain is never at rest; even a resting brain consumes 10% of the body's energy, while accounting for only 2% of its mass. In addition, the body is simply not able to maintain intensive brain work for a long time, after some time it inevitably comes nervous exhaustion. In addition, the brain, deprived of the necessary resources (oxygen first of all), almost instantly (within 5 minutes) dies.
Optimization
I believe that the majority of Khabrovites to present moment have already imagined how to optimize the energy costs of the brain. IT specialists in this regard did not come up with anything better than nature.
Option A: limit brain activity to only really extreme situations. On human language this mechanism is called laziness. Man instinctively strives not to think, as long as it is not needed. Many animals, such as cats, generally constantly stay in one of two states: either sleepy slumber or hyperactivity. Laziness is the engine of progress in the most literal sense.
Option B: cache. Lay in as many predefined behaviors as possible and turn on the brain only when the autopilot cannot solve the problem itself. Such optimization is characteristic primarily of small animals, but, as it is easy to see, having shown a minimum of observation, a person also uses it with might and main.
By the way, this is where the famous absurd myth comes from that a person allegedly uses ten (five, two - underline as necessary) percent of his brain. At a particular point in time and at rest - in some approximation, yes. Because using the entire brain unnecessarily is expensive and unreasonable. But keeping 90% of the brain unused at all is even more expensive and unwise.
Reality
It often seems that human behavior is stupid and illogical. However, in the light of the previous paragraph, it is quite clear that human behavior absolutely smart and logical. The question “what were you thinking about” usually has a simple answer: nothing. to a person peculiar not to think about anything, and from an evolutionary point of view, this is the most beneficial program.
Of course, in modern world most of humanity has no problems with nutrients and energy optimization mechanisms are not needed. But, alas, we are not able to change our own genetic program; and there is no guarantee that a different scheme of the brain will be more optimal for homo sapiens.
Remember is expensive
Let's move on from thinking to memory. To understand the processes of memorization and recall, it is useful, first of all, to learn one simple thing: human memory is volatile. The body's resources are continuously spent on storing information. I think you already understand what this means :-).
First, memory is divided into short-term and long-term. Only a small part of the flow of information gets into long-term memory.
Second, memories are constantly being lost. The more time passes, the less information about the event remains in memory.
Remembering by chance
The probabilistic essence of memorization is also superimposed on these processes, already unhappy for students :-) . The fact is that memorization is the formation in a neural network of stable cyclic networks containing the necessary information. This process is not very fast and rather unpredictable. It is impossible to predict with any accuracy at what point the configuration of neurons will change. That is why a person often remembers completely meaningless and unnecessary information for the rest of his life - because it so happened that at the time of the formation of a new configuration of neurons he was thinking about this nonsense. In order to guarantee memorization, it is necessary to constantly update the information for quite a long period time.
Memory lies
As mentioned in the previous section, a person needs memory primarily in order not to think. Memorized decisions and behaviors allow you not to strain your brain, but to act on autopilot. This is in fact main function memory.
However, due to the fact that the memory is volatile, it is impossible to remember all the necessary information. On the one hand, constantly new information, which could potentially be important. On the other side, old information constantly losing relevance. Thus, old memories constantly compete with new ones for memory space. Moreover, in order to maximize full use available resource, new and old information signals circulate along the same paths. As a result, old memories are constantly distorted, which over time leads to rather unexpected effects, up to the complete inconsistency of the old memory with reality, and the old memories become more and more idealized over time. This is true not only for humans, but for other animals too.
Welcome to the Real World
I don’t know about you, but I began to understand the behavior of people much better after reading all this. Ideas about why the brain behaves the way it does, and not otherwise, in my opinion, are much more useful than abstract recommendations about how to increase performance and improve memory. I hope you find them useful too.
