How many calories does the brain spend per day? How to manage brain energy
This post is for those who feel sad and despondent at the thought of going to the gym or jogging, who most like to sit at the computer, and want to lose a few pounds at the same time. Of course, nothing comes for nothing, and in order to lose weight without getting up from your favorite computer chair, you will 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 completed for 1.5 hours. One group did nothing, the second group memorized texts from paper, and the third group worked at the computer. As a result, the group that memorized texts from books spent 200 kcal more than the 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 extreme concentration for 20 minutes, the brain is able to “eat” such an amount of energy that it would not have spent the entire day spent without mental activity. Therefore, it can be quite difficult to concentrate 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 active work its costs double. It is generally accepted that when a person strains his 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 is that emotional experiences increase energy consumption by 10-20%, and intellectual activity accompanied by emotions by 30-40%. Scientists from the Research Institute of Physiology named after. 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 spent 750 kcal on intellectual activity, and during the exam - 1000-1100 kcal.
So, taking into account all of the above, for fans sedentary image In life, we can advise the following:
Think more
Viewing public pages on social networks, cheerful correspondence with friends or toys (except for those genres where you need to use your brain) will not burn 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 crosswords. At the same time, it is advisable not to be distracted and 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, the level of glucose, a substance that feeds brain cells, drops sharply in the body. To make up for losses after mental activity, a person really wants to eat. This does not mean that the body really needs additional calories, it just needs glucose.
Scientists believe that a cup of sweet tea will be enough to replenish 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 go away.
Emotional experiences
Of course, you won’t be able to give yourself stressful exams every day, but you can still do something. For example, solve logic problems against time or play chess with someone. So to intellectual activity an element of excitement is added. More excitement, more emotions, more calories burned.
Something new
The part of the brain that is working consumes more energy, so energy consumption can be increased by alternately turning on different departments brain, that is, by solving multi-part tests or playing puzzle games.
Besides, the brain consumes more energy when solving non-routine problems. If you are a humanitarian, try to solve logic problems, remember school course geometry or algebra. In general, engage in new types of intellectual activity - this not only increases energy expenditure, but also helps develop the brain.
And finally, we can’t help but mention that simple walking burns 4 kcal per minute, so if you’re tired of thinking, go for a walk.
If children grow up like weeds (dandelions are weeds, after all), then their brains burn like a torch. It is quite expensive to maintain an adult brain, which uses 17% of the body's total energy, although it makes up only 3% of body weight, but this is nothing compared to the energy costs of development baby brain. The brain reaches almost full volume by 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 expensive. From 3 to 8 years, 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) scanning, which measures levels of radiolabeled glucose, a sugar that is the main fuel for neurons (see figure). Radio markers are created by adding radioactive atoms, allowing movement to be traced chemical substance 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 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 the age of 2-3 months, energy consumption increases by temporal, frontal and occipital lobes cerebral cortex, as well as in the subcortical basal ganglia which, among other things, control vision, spatial orientation and movement.
Between 6 and 12 months of age, energy consumption increases frontal lobes cerebral cortex when children first begin to control their behavior.
The amount of energy consumed by the brain continues to increase until age 4, and begins to decline around age 9, consistently reaching “adult” levels in different regions as they mature. This process is completed between the ages of 16 and 18.
Because the neural connections develop on different stages During adolescence, there are several sensitive periods, each of which corresponds to a specific brain function. Sensitive periods are especially characteristic of developing brain babies and toddlers because it grows very rapidly, but they can occur at other times. Some sensitive periods begin and end before birth—for example, the development of touch, based on the baby's sensations in the womb (see Chapter 11). Many occur soon after birth, for example, the first interactions with loved ones form stress-responsive brain connections (see Chapter 26). Other sensitive periods, such as learning the grammatical aspects of language, continue until the end of childhood and into adolescence.
As we described in Chapter 2, programmed chemical signals direct axons to target sites and ensure the formation of a large number of synapses. Once these basic elements are in place, life experiences can influence further development, controlling the activity of axons and synapses. Synapses of neurons that are more often activated, with more likely will be maintained and strengthened due to the plasticity of biochemical passages to the target cell, while dysfunctional synapses (i.e. connections between two neurons) weaken or disappear. Synaptic activity can also cause the growth or retraction of axonal or dendritic branches. Cells that fire together bind tightly to each other (see Chapter 21).
After completing these plastic changes brain architecture is less amenable to modification in the future, either because additional axons and synapses are no longer accessible or because the biochemical pathways that determine synaptic activity change with age. In this regard, the brain uses sensory experience to form connections in the neural circuit, cutting off unnecessary connections and maintaining the strongest and most active ones to maintain patterns of perception and behavior 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 the brain increases rapidly from birth to a peak at 8 months of age, and then gradually decreases until age 5 as visual abilities develop (see Chapter 10). The maximum reduction 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 were not examined). In the frontal cortex, synaptic 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 7 and 12 years of age.
The process of synapse elimination has been studied in much more detail in other primates, and the results are generally consistent with fragmentary data from human studies. In rhesus macaques, the explosive growth of synapses in the first few months after birth is replaced by first a gradual and then an accelerating decrease in their number in childhood. Adult levels of synaptic density are observed after puberty. Although this increase in animals follows similar trends, the decrease occurs on different schedules in different individuals, reinforcing the idea that it is events in environment influence the process of synapse elimination.
In all areas of the cerebral cortex studied in monkeys, the development of synapses follows a similar time schedule. It is not yet clear whether this principle of simultaneous synaptic development 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 edit.). However, due to age-related gaps in human synapse counts and inter-individual discrepancies, the evidence to support this position is incomplete. In any case, measuring brain energy in children shows that the differences in the timing of development of different areas of the cortex are relatively small and that the elimination of synapses continues throughout childhood (see sidebar above: “Did you know? Your child’s brain uses half the body’s energy”). .
To understand how experience influences synaptic changes during the sensitive period, we must look to studies in laboratory animals. Barn owls hunt in the dark and must pinpoint the source of sound to know the position of their prey. They do this by comparing the difference in arrival times sound signal between the left and right ears, since sounds coming from the left reach the left ear before the right, and vice versa. More complex calculation of the upper or bottom position sound source is determined by the differences in loudness created by the shape auricle. The owl's brain receives information about time discrepancies and volume changes and uses it to create a brain map of the sound source. Because the incoming information 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 young children. Your baby's brain has specific preferences for 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 owlets with prismatic glasses that visually shifted objects to one side. At first, when trying to move around with the 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 map of sound space also shifts as a result of the response to the prism glasses, although the auditory information remains unchanged.
This shift occurs because neurons that receive time and loudness information extend their axons and connect to new neurons in another part of the map. The old connections remain in place, although their synapses weaken, allowing owls to revert to the old scheme of things after their glasses are removed. This perceptual plasticity occurs during the sensitive period, up to approximately 7 months. Adults whose sensory period has ended have a much more difficult time rewiring connections because their axons are confined to a smaller area of the brain and the neural circuitry can no longer carry signals beyond the range established in youth.
All of our organs burn calories when they perform their functions, right? So, since the brain is an organ, thinking burns calories, and thinking harder burns more calories?
Remember, in cartoons, when the hero thinks, a large number of is steam coming out of his ears? Okay, a bit of an exaggeration, but a major shake-up does happen there when we make a mental effort. The brain burns a lot of calories at rest, and external 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 approximately 20 percent of our total caloric intake. The percentage is even higher in children whose brains are still developing. The average newborn's brain uses about 75 percent of its available energy, an 11-year-old's uses one-third, and the average adult's brain uses about 75 percent of its available energy.- about 20 watts.
About 60 - 80 percent of the brain's energy is used for "neural signaling" - I think that's what ordinary people who devote their lives to repairing and replenishing supplies call it. Just like any physical matter, the brain burns glucose, which reacts with oxygen to produce fuel. Glucose and oxygen are carried by the blood, so during intense mental activity we may experience an increase in cerebral blood flow and an increase in the use of glucose and oxygen, and as a result, greater energy consumption.
And this is what scientists discovered in the process of their research:
In 1878, an Italian scientist working with a patient with a skull injury discovered that the subject's brain pulsed faster when the subject solved arithmetic problems.
In a 1995 study, glucose consumption and cerebral blood flow of volunteers taking a card sorting test increased by 12 percent.
A 1987 study that asked volunteers to think about day walk, increased their brain metabolism by 10 percent.
A 1992 study of Tetris players found that if they played the game 5 days a week for a month or two, the brain's glucose consumption 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 consumption increased, oxygen use — no, this means that there was no increase in combustion - the brain did not "burn" noticeably more"fuel". This is exactly what neuroscientists are still trying to figure out. Cerebral blood flow does not increase quickly enough to provide an immediate increase in energy consumption; researchers now speculate that blood flow speed increases to cool the brain or carry away waste products. The breakdown of glucose 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 share of energy, most of which is spent on thinking. That said, some brain scientists say we should have a different view of what's going on there. Previously, it was believed that the brain responded extremely passively to external stimuli. Now that we understand that external events do not influence changes in the brain's energy consumption as much, a different picture emerges: most of our mental activity occurs strictly in our heads.
"So what", - you say. Give me a sec. Neurologist Marcus Raichl, writing for Science magazine, 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 the team of “pipe-smoking dwarfs” between our ears who take in all our feelings, think about them, and organize our next actions.
And these dwarfs work quite efficiently. The human brain contains approximately 86 billion neurons, occupying a volume comparable to a grapefruit (gorillas and orangutans, the closest brain-sized primates to us, have about 33 billion). The most powerful electronic brain in the world today is a supercomputer. Titan, located at 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, the computing power of the human brain is said to be 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 its performance is approximately 50 petaflops per watt. The performance of a typical supercomputer is 2.5 gigaflops per watt. This is 1/20 millionth the efficiency of the brain. In other words, a supercomputer Titan – 8.2. a mega-watt liquid-cooled monster the size of a large suburban home. A more powerful human model runs on Cheerios cereal that 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 man weighs 1424 g; by old age, the brain mass decreases to 1395 g. The largest female brain by weight is 1565 g. 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 the male brain was 1372 g. The smallest weight of a normal non-atrophied brain belonged to a 31-year-old woman - 1096. Dinosaurs, reaching 9 m in length, had a brain the size of 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 breathing rate and normalizes brain wave vibrations, promoting the body’s self-healing process. Believers go to the doctor 36% less often than others.
4. The more educated a person is, the lower the likelihood of brain diseases. Intellectual activity causes the production of additional tissue to compensate for the disease.
5. Engaging in unfamiliar activities is the best way to develop your brain. Communication with those who are superior to you in intelligence is also potent drug brain development.
6. Signals in nervous system humans reach speeds of 288 km/h. By old age, the speed decreases by 15 percent.
7. The world's largest brain donor is the monastic order of Sisters Educators in Mankato, Minnesota. The nuns donated about 700 brain units to science in their posthumous wills.
8. The most high level intellectual development(IQ) was demonstrated by Marilyn Much Vos Savant from Missouri, who at the age of ten already had the average IQ for 23 year olds. She managed to pass the most difficult test for entry into the privileged Mega Society, which includes only about three dozen people who have such high rate An IQ that occurs in only 1 person in a million.
9. The Japanese have the highest average national IQ in the world -111. 10 percent of Japanese have a score above 130.
10. Superphotographic memory belongs to Creighton Carvello, who is able to remember the sequence of cards in six separate decks (312 pieces) at once. Typically, in our lives we use 5-7 percent of our brain capacity. It’s hard to imagine how much a person would have accomplished and discovered if he had used at least as much more. Scientists have not yet figured out why we need such a safety margin.
11. Mental work does not tire the brain. It has been discovered that the composition of the blood flowing through the brain remains unchanged throughout its active activity, no matter how long it lasts. At the same time, blood that is taken from the vein of a person who has worked all day contains a certain percentage of “fatigue toxins.” Psychiatrists have found 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, a person’s perception of information goes without thinking processes and analysis, i.e. a person escapes reality. In this state (as with meditation), delta waves appear in the brain, which are usually recorded in infants in the first six months of his life. Perhaps it is this fact that influences the fact that people who regularly perform religious rites get sick less often and recover faster.
13. For full-fledged work brain needs a drink sufficient quantity liquids. The brain, like our entire body, consists of approximately 75% water. Therefore, to keep it healthy and in working condition, you need to drink the amount of water required by your body. Those who are trying to lose weight with the help of pills and tea, which expel water from the body, should be prepared for the fact that at the same time as they lose weight, they will also lose brain performance. Therefore, they should do as they should - take any pills prescribed by the 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 a morning jog and breakfast, which enhance the metabolic processes occurring in your body, to do a little brain exercise. This means that you shouldn’t turn on the TV in the morning, but rather do a little reading or do 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, the frequency range is wider than that of male voices. Human brain you have to “decipher” the meaning of what the woman is saying, using your additional resources. By the way, people suffering from auditory hallucinations more often hear men’s 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 there are people on Earth. Each of them is connected to 10,000 other neurons. By transmitting nerve impulses, neurons ensure continuous functioning of the brain.
18. People only use 10% of their brain. It is a myth. Even though not all the secrets and capabilities of the brain have been revealed, it is stupid to say so - the brain always uses as many resources as it needs at the moment. Saying that we use 10% of our brain is the same as saying that we use one percent of the radio's capabilities - we listen to only one wave, but there are a hundred more 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 11:30 pmHow the brain really works
- GTD
On Habré there are quite popular articles about various techniques increasing performance, 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 the book by S.V. Savelyev “The Origin of the Brain,” which I strongly recommend reading, along with the works of Richard Dawkins and Konrad Lorenz.
The brain evolved as a flexible, versatile, and fast solver. Possessing a brain makes an animal much more adaptable, especially in extreme situations. However, everything comes at a price: the brain is an extremely expensive organ. In humans, an intensively working brain consumes a quarter (!) of the resources of the entire body. Another 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 intense brain function for a long time; after some time, it inevitably occurs. nervous exhaustion. On top of everything else, the brain, deprived of the necessary resources (oxygen, first of all), dies almost instantly (within 5 minutes).
Optimization
I believe that the majority of Khabrovsk residents at this moment have already imagined how to optimize the energy expenditure of the brain. IT specialists haven’t come up with anything better than nature in this regard.
Option A: Limit brain activity to truly extreme situations. On human language this mechanism is called “laziness”. Man instinctively strives not to think, as long as it is not necessary. Many animals, for example cats, are generally constantly in one of two states: either sleepy dormancy or hyperactivity. Laziness is the engine of progress in the most literal sense.
Option B: cache. Establish as many predefined behavior patterns as possible and turn on the brain only when the autopilot cannot solve the problem on its own. Such optimization is characteristic primarily of small animals, but, as is easy to see, with a minimum of observation, humans also use it with all their might.
By the way, this is where the famous absurd myth comes from: that a person supposedly uses ten (five, two - underline as appropriate) percent of his brain. At a specific moment in time and at rest - to some approximation, yes. Because using the entire brain unnecessarily is expensive and unwise. But keeping 90% of the brain unused is even more expensive and unwise.
Reality
It often seems that a person's behavior is stupid and illogical. However, in light of the previous paragraph, it is quite obvious that human behavior absolutely smart and logical. The question “what were you thinking about” usually has a simple answer: nothing. To a person characteristic not to think about anything, and from an evolutionary point of view this is the most profitable program.
Of course, in modern world Most of humanity does not have problems with nutrients and mechanisms for optimizing energy consumption 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 brain function will be more optimal for homo sapiens.
Remember is expensive
Let's move 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 consumed to store 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 ends up in long-term memory.
Secondly, memories are continuously lost. The more time passes, the less information about the event remains in memory.
Memorizing by accident
These processes, which are already unhappy for students :-) are also superimposed on the probabilistic nature of memorization. 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 quite unpredictable. It is impossible to predict with any accuracy at what moment the configuration of neurons will change. This is why a person often remembers completely meaningless and unnecessary information for the rest of his life - because it so happened that at the moment of the formation of a new configuration of neurons he was thinking about exactly this nonsense. In order to ensure memorization, information has to be constantly updated over quite a period of time. long period time.
Memory lies
As was said in the previous section, a person needs memory primarily in order not to think. Memorized decisions and behavior patterns allow you not to strain your brain, but to act on autopilot. This is actually main function memory.
However, due to the fact that memory is volatile, it is impossible to remember all the necessary information. On the one hand, it constantly comes new information, which could potentially be important. On the other side, old information is 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 quite unexpected effects, up to a complete discrepancy between the old memory and reality, and the old memories become more and more idealized over time. This is typical 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 people’s behavior 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 on how to increase performance and improve memory. I hope you find them useful too.
