What kind of mysterious substance is in our head? It allows us to move, see, feel, understand and dream. But how does this intricacy of neurons and synapses manage to guide our body and our thoughts?
Section of the website " Brain"invites you on a fascinating journey inside yourself, into the mysterious and amazing universe of the human brain...
In this picture different colors The most important parts of the brain are highlighted. The red stripe is the frontal region. Here abilities such as foresight, imagination, creativity, a sense of responsibility and a tendency to introspection are acquired. The light green stripe is the anterior central gyrus. Here is the center that controls all the muscles that obey our will. The blue stripe is the posterior central gyrus. It complements the anterior central gyrus. All information about the sensations experienced by our body (pressure, pain, temperature, etc.) is collected here and analyzed here. The blue spot marks the center responsible for our orientation in space. This part of the brain differentiates between left and right side and performs calculations. Violet color The occipital lobe is shaded. By processing signals received from the retina, this part of the brain recreates a picture of the world around us. The orange spot is the speech center, and the yellow spot is the auditory center. He not only perceives speech, but also understands it.
Through a hole in the skull, the foramen magnum, nerve pathways penetrate the skull. Right here spinal cord and the medulla oblongata - a thickening resembling an onion - pass into brain stem, where many neurons are concentrated. They form two vital centers of the brain: respiratory and regulating blood circulation. If this part of the brain is damaged, the person dies. Above these centers is the reticular substance of the brain stem - an incredibly dense interweaving of neurons. This area of the brain is its largest information exchange. 10 million nerve pathways ending here, coming from spinal cord. They connect all parts of the body to the brain. Signals coming into brain, flock here, are analyzed here, and then transported to one or another part of the brain.
One of these specialized parts of the brain is cerebellum. It is located above the brain stem. Only a thin medulla separates it from occipital bone. This small organ, the size of a tangerine, is cut with deep grooves. Cerebellum continuously receives thousands of messages: about the position of arms and legs, about the direction of gaze, about how images are placed on the retina of the eyes and how fluid moves in the labyrinth inner ear, etc. All this information is remembered, analyzed, compared - such work takes a few fractions of a second. As soon as the cerebellum notices any danger, it will immediately give an order to the muscles, and they will change the position of the body to prevent trouble. In addition, the cerebellum sends “reports” to the cerebrum. From them it is clear how a person feels, whether he is moving or resting, nervous or happy.
Brain stem- not a solid organ, it consists of two halves fused in the middle - left and right. This bifurcation is especially noticeable where one of the four cerebral ventricles filled with cerebrospinal fluid is located between the processes of the brain stem. The paired processes are called the diencephalon. This most ancient part of the brain stores evolutionary experience that has accumulated over millions of years. The lower part of the diencephalon, the hypothalamus, closely monitors events on which a person’s well-being depends or which threaten him with disaster. At his command, a person’s mood changes dramatically. It is here, in the hypothalamus, that feelings are born: hunger, thirst, aggression, rage, fear and uncontrollable sexual desire. In addition, the hypothalamus controls the pituitary gland: it forces this gland to secrete hormones that affect vital processes occurring in our body.
The upper part of the diencephalon is called the thalamus. Messages from the most different parts body. Thalamus assesses how important they are for a person. When they are really significant, we feel uneasy. The diencephalon plays a big role in the lives of each of us. Dark, vague emotions lurk here: unreasonable fear, unbridled rage... Calls for reason, objectivity, peace are met with resistance in this part of the brain. The diencephalon tenaciously clings to bad experience of the past. The real traces of the activity of this part of the brain are selfishness, hatred, belligerence and a senseless thirst for destruction. These unkind feelings arise again and again in a person’s soul and sometimes begin to control his life.
What is a big brain
Yes, diencephalon plays a fatal role, but let’s not dwell on it any longer. So, a large brain covers it on top. In its lower layers there are those centers that determine the dominant mood of a person, his temperament, and disposition of spirit. They are hidden under the cerebral cortex, riddled with grooves.
Numerous experiments on animals, as well as observations of sick people, helped scientists draw up an accurate diagram cerebral cortex, show where the basic abilities of a person are formed.
It is in these centers that it is decided once and for all what kind of person will be - lethargic or energetic, whether he will strive for a lot or be content with little, whether he will be an optimist or a pessimist who sees everything in black. This part of the brain determines a person’s attitude to life, which is reflected in the structural features of his face, hands, and manifests itself in his voice, gait and handwriting. But only small children have a truly sincere facial expression. Adults - due to experience or upbringing - mask their feelings and therefore behave “unnaturally”. On top, the large brain is shrouded in a cerebral cortex, reminiscent of a folded mantle. By and large, it is this part of the brain that makes a person human. All his abilities and capabilities are concentrated here - in a three-millimeter layer of neurons.
A deep furrow divides cerebral cortex into two halves - front and back. The posterior part of the cortex receives and analyzes visual and auditory signals, as well as sensory sensations. The front half, on the contrary, reflects and commands. Experiments on animals and observations of sick people helped to create an accurate diagram of the cerebral cortex. The unique—and therefore most interesting—part of it turned out to be the frontal region. None of the animals have anything like this. All those qualities that are inherent to a person are concentrated here: foresight, imagination, creativity, a tendency to introspection and a sense of responsibility. This is where the concepts of “I” and “you” were born. In this area of the brain (its area is only about the size of a palm), as if in a mirror, all of Nature is reflected, and incomprehensible depths appear in this reflection. Many believe that the Lord God himself is depicted here.
It's time to write about what models of brain functioning and structure I adhere to, so that in the future you and I will be on the same page. Naturally, these are only models and their “comprehensiveness” is limited by the framework of themselves. But the brain, comrades, is such a Solaris that if we do not at least approximately understand how it works, then we will drown in false assumptions regarding other people’s and our own behavior. Because in what happens to us in life, the share of conscious actions and logical thinking is negligibly small, and our behavior is constantly under the unconscious influence of emotions. I won’t discover America here, but it will be useful to have a common base for further communication. To start:
McLean's triune brain model
The central part, or brain stem, is the so-called ancient brain, reptilian brain. He's wearing it up midbrain, old brain or limbic system; it is also called the mammalian brain. And, finally, on top is the human brain, or more precisely, the higher primates, because it is present not only in humans, but also, for example, in chimpanzees. This is the neocortex, or cerebral cortex.
Ancient brain, reptilian brain is responsible for performing the simplest basic functions, for the daily, second-by-second functioning of the body: breathing, sleep, blood circulation, muscle contraction in response to external stimulation. All these functions are preserved even when consciousness is turned off, for example during sleep or under anesthesia. This part of the brain is called the reptile brain, since reptiles are the simplest living creatures in which a similar anatomical structure is found. The “flight or fight” behavior strategy is also often attributed to the functions of the reptile brain.
Midbrain, limbic system worn on the ancient brain is found in all mammals. It is involved in the regulation of functions internal organs, smell, instinctive behavior, memory, sleep, wakefulness, but primarily the limbic system is responsible for emotions (which is why this part of the brain is often called the emotional brain). We cannot control the processes occurring in the limbic system (with the exception of the most enlightened comrades), but the mutual feedback between consciousness and emotions exists constantly.
Here's a comment gavagay on the same occasion: "Direct dependence [ between consciousness and emotions] is not there - therefore we have no choice, say, whether we should be afraid or not. We get scared automatically, in response to an appropriate stimulus from the outside. But an indirect connection is possible and for some situations it is very significant. The functioning of the limbic system depends on signals entering it from the outside, including from the cerebral cortex (via the thalamus). And our consciousness nests in the cortex. It is because of this that we will be afraid of a gun pointed at us - even if we have never been shot at. But a savage who does not know what a pistol is will not be afraid. And, by the way, it is precisely because of the presence of this indirect dependence that such a phenomenon as psychotherapy is in principle possible."
And finally, neocortex, cortex cerebral hemispheres brain, responsible for higher nervous activity. It is this part of the brain that is most developed in Homo sapiens and determines our consciousness. Accepted here rational decisions, planning is carried out, results and observations are assimilated, decisions are made logic problems. We can say that our “I” is formed in this part of the brain. And the neocortex is the only part of the brain in which we can consciously track processes.
In humans, all three parts of the brain develop and mature in this order. A child comes into this world with an already formed ancient brain, with a practically formed midbrain and with a very “unfinished” cerebral cortex. During the first year of life, the ratio of a newborn's brain to an adult's size increases from 64% to 88%, and the brain mass doubles; by 3–4 years it triples.
Now it is clear why emotions play a decisive role in raising children. Children do not act to spite you, they do not seek to manipulate you; manipulation requires careful planning. And they are driven by basic emotions: the desire for contact and intimacy, fear, anxiety. When we understand this, it will become much easier to understand the child.
And we ourselves, adults, are not as rational beings as we would like to think. Sue Gerhardt wrote wonderfully about this (Why Love Matters: how affection shapes a baby's brain):
“It may be ironically noted that recent discoveries in neurophysiology have revealed that feelings play a greater role in our lives than reason. All of our rationality, so respected by science, is based on emotions and cannot exist without them. As Antonio Damasio points out, the rational parts of our brain cannot work in isolation, but only simultaneously with the parts responsible for basic regulatory functions and emotions. “Nature has built a rational system (apparatus) not just on top of the biological regulatory system, but from her and inseparable from her" (Antonio Damasio, Descarte's Error)."
Picture from here: Carl Sagan "Dragons of Eden".
Neanderthal and Cro-Magnon man lived together in the same natural landscape for 50-24 thousand years. Neanderthals became extinct, but sapiens remained. In ancient man, the brain size was 1600-1800 cm3. Average volume modern man is 1400 cm3. And as a result, 250 cm3 were lost over 25 thousand years, which is very significant. This is explained social nature modern man, and the fact that society takes on a lot from the functions that the individual performed in the past.
But such reasoning cannot be considered obvious. Firstly, social relations have always existed at all stages of human evolution, therefore, they should have been structurally realized in the development of the brain even at the stage of lower apes. Secondly, social relationships have only become more complex, and, therefore, the brain that supposedly serves them must also become more complex. Thirdly, perhaps such a decrease in brain size indicates a banal degradation of some brain structures developed by our venerable ancestors due to their uselessness for modern man?
I will try to describe a hypothesis that explains the evolution of our brains. Let's start with that ancient man who did not yet know how to use various devices, but only began to master them. Each of us goes through this difficult period of your life from 1 to 4 years. At this point, brain size relative to body size is largest. In the process of development, the ability to use a variety of objects is acquired, and gradually the ratio of brain and body sizes changes towards the body. It seems natural to us, since everything happens during the period of body growth.
Ancient man, not possessing devices (an obsidian knife, spearheads, arrows, etc.), had to replace the absence of these things with the complexity of its behavior, but at the same time have the potential for the development of technology. Consequently, his brain was more loaded with information about the world around him. Moreover, all the information was vital.
Further development was accompanied by the invention of more advanced tools and weapons (spears and tips for them); the use of fire for making tools and cooking led to the degradation of the part of the brain responsible for fighting predators with bare hands, night vigil, searching for food that can be consumed without the use of fire. The flexible structure of the evolving Cro-Magnon brain made it possible to replace lost structures with new ones responsible for associations. Development went in the direction of developing creative abilities, but they required less expenditure in volume than to fight the objective circumstances of life in the absence of tools and weapons. Consequently, during replacement there was a reduction in the volume of incoming information and brain size.
Each new invention replaced some function of the brain, and led to the degradation of some parts and the development of others. Information coming from the outside world lost its vital importance, and gained social importance. The invention of javelin throwing freed mankind from the need to get close to the animal when hunting, which reduced the brain, for example, by 10 cm3, and the invention of the bow - by another 10 cm3. Since the inventions affected the brain in a complex manner in many ways simultaneously, the overall effect turned out to be so significant (250 cm3). If we assume that the degradation of the brain is associated with the stages of inventions that took on some of the functions compensated by previously complex human behavior, then modern computerization replaces human computing abilities and, in combination, many other functions. Following the logic of the replacement hypothesis, 2-3 generations will pass and a person will lose another 200 g of brains and will approach Homo erectus, from which he descended. I wish you success!
Thesis – every appearance of a new tool for business +, for brains -. Laziness may have made us human, but it has not made us smarter.
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