The newborn imitates the smiling mother. Visitors to the cinema jump in the chair from the dangerous pirouettes of the protagonist. At the lecture the student becomes infected with a yawn from his neighbor. All this is the result of the work of an unusual group of nerve cells called mirror neurons.
In the middle of the 20th century, Canadian neurosurgeon Wilder Penfield developed a method for the treatment of epilepsy, called the Montreal procedure. Penfield found the exact location of the focus of the disease, stimulating the patient's brain with a thin electrode. All the time of the surgical procedure patients with a cut skull box were conscious and described the doctor their feelings. After discovering the epilepsy focus, Penfield physically destroyed diseased nerve cells.
The Penfield procedure helped many patients get rid of the most severe seizures. But for science, the importance of the Montreal procedure was different. In parallel with the search for foci of epilepsy, Penfield realized the old dream of physiologists: carefully studying the response of patients to stimulation of different areas of the cortex, he delineated the cerebral cortex of the human brain into functional areas.
Classical physiology considered the cortex clearly divided into zones, sectors, fields and departments. But the main division is the division of the cortex into the sensory, that is, the perceiving part, and the motor, that is, giving orders to the muscles and other organs of the body. Both the sensory and the motor cortex, in turn, were divided into sections, each of which corresponded to a certain area of the body: the face, the tongue, the thumb.
Penfield confirmed and strengthened these experiments with their experiments: sensitive areas of the brain are located separately from the motor. For several years at universities around the world, the enthusiastic followers of a Canadian surgeon, not spoiled by the dreamers to expose their convolutions by patients, attacked the monkeys - especially the rhesus monkey.
Physiologists began to crush the cortex into more and more specialized sites. In the sensory departments, the electrodes recorded a reaction to external stimuli: touch, sound, light. In the motor departments, on the contrary, microdischarges of current were sent and watched what macaques twitch muscles.
This generally successful electrophysiological colonization of the monkey (and human) cortex did not dispense with separate territorial disputes. One of these conflicts was the question of the lower part of the cerebral field number 6.
How to turn science around one gyrus
Number 6 is taken from the classification of Brodmann, another cerebral "surveyor", who in 1909 outlined the cortex by the appearance of nerve cells. The sixth field of the monkey brain - a small area on one of the gyri - introduced physiologists into difficulty. It was located in the motor cortex. But it was difficult to draw him into the controlled organs for some reason: the monkey reacted to stimulation not unambiguously, as when checking the knee reflex, but unpredictably or not at all. Some more dreamy scientists began to discuss the idea of a unifying center, a site compiling the movement into holistic behavioral acts. To most physiologists deviations from a simple and understandable brain map seemed superfluous. They considered the lower field 6 simply an adjunct of the neighboring field 4, which helps him to control muscles.
In 1988, a group of scientists from the University of Parma in Italy, led by Giacomo Rizzolatti, decided to clarify the situation. They combined the traditionally "motor" approach with "touch". Scientists have introduced macaques into the lower field 6 electrodes, with which neurons could be stimulated, and "listen".
"Motor" approach - to shock and see the reaction - quickly gave interesting results. It turned out that electrostimulation of the movement still caused, but not everywhere. Where it caused, it was very strange: for example, at the same time with the hand twitched lips. The Rizzolatti group checked to see if the electrodes were too thick, but everything was in order: stimulation of individual neurons or groups of neurons did indeed lead to the activation of several motions simultaneously.
"Sensory" approach - measuring the activity of a neuron in different situations - was even more interesting. The same neurons that triggered the movement were activated when there was no movement. For example, if the left hand is moving, there should not be a "right-handed" motor activity. But the cells in the lower zone 6 in the macaques usually reacted identically on both sides. These motor signs were included in all the senses in the most "sensory" situations: when touched by a person, for example. Or even from a glance!
Real motor neurons, based on the dogmas of physiology, clearly know their place and of all six senses only work with the sixth - the muscular. Suddenly it turned out that the whole area of the motor cortex not only can not decide what it controls muscles, but it is activated by almost any external action. But the main discovery was yet to come.
Abstract neurons
Rizzolatti became interested in these unusual cells with the properties of the motor and sensory parts of the brain. He decided that their role should be connected with the unification of behavioral programs: the compilation of movements and information about the surrounding world into a single meaningful act. In search of possible sources of information affecting these cells, scientists made an unexpected observation: some of the neurons were activated when the action was performed not only by the macaques themselves, but also by the researcher. For example, the same cells were included when the macaque grabbed an outstretched stick and when it looked at scientists making the same movement.
How is this possible? The reaction of the cell did not depend on where the researcher stood, how he looked, what he was grabbing. The neuron was activated in response to the sense of grasping. The image of the hand that closes on the object. That is, it turned out that the motor cortex - traditionally quite a "stupid" part of the brain - should be able to analyze virtually abstract concepts. Even if she did not do this herself, but receiving signals from somewhere in the higher sections of the cortex, the question remained: why in the motor cortex there are abstract matter?
The first magazine, in which Rizzolatti presented the results of his work, rejected the article "in the absence of widespread interest." But the next, less well-known magazine, the article took, having made, probably, the best PR-solution for all time of its existence.
The article caused a storm of interest. Unusual neurons "reflecting" the behavior of another individual, were baptized "mirror" and instantly became one of the most popular topics in the sciences of the brain. What did they like about biologists so much?
Mirror neurons, asserted by cognitive psychologists inspired by Rizzolatti's works, react to an abstract idea (the idea of grasping). Is not this our ability to understand each other? If you think about it, the very fact that animals can understand and even partly experience what happens to another animal without having physical contact with it is an amazing property of the nervous system. Mirror neurons are the first known mechanism that can underlie the ability to understand someone in principle.
What for the brain mirror
Mirror neurons, Rizzolatti suggested, represent a way to "simulate the movement": rehearse it with the hands off. The brain itself does not know what action is for - a virtual simulation allows you to try it on yourself and understand what will happen.
Indeed, the data indicate that activation of mirror neurons in the absence of movement helps macaques understand the purpose of an action. In an experiment, when a researcher grabs a stick in front of the eyes of a macaque, two-thirds of its mirror neurons do not depend on how to grasp the stick (fingers or an entire brush), but all the cells "remain silent" if the grasping movement is done without a stick. That is, the final result of the action is coded: a stick in the hand. Even to see the action is not necessary: for example, if noisy to prick nuts, then the macaques from the loud sound activate the same cells as if she did it herself.
"Coding purposes" can be constantly updated. For example, a neuron is activated in response to a snatch of food - by the macaques themselves or by someone else. If you grab the food with forceps, then the neuron will not activate: the forceps are not the hand. But if you teach the macaque to use forceps, then the difference between the hand and the forceps for it will disappear, and the mirror neuron is activated in both situations.
According to other sources, mirror neurons help monkeys understand not only the purpose of the action, but also its cause. For example, a macaque remembers that when the ball is shown the researcher takes it away, and when the apple is shown, it sends it to the mouth. Mirror neurons, when observing a scientist, are activated almost instantly - long before the goal in each specific case becomes clear. But, depending on the edibility of the subject in the macaques, different groups of cells are activated. That is, mirror neurons can react not only to the target, but also to the cause.
Finally, in 2009, all the same scientists from Parma, in collaboration with German specialists led by Antonino Casile, showed that in addition to the goals and causes of the actions of others, the activation of mirror neurons can contain information on the significance of these actions. Different mirror neurons were activated in the macaques, depending on the distance to the object. Some of them worked only when they grabbed food right in front of the eyes of a macaque. The other part - with the same action in the distance. Some neurons depended on absolute distances, and some - on subjective: "long-range" changed depending on the interest. "Reflect" you need only the most significant actions: those that are nearby, or those that are interesting.
The most obvious application of mirror neurons is imitation. To simulate the action "grab a stick" is easier than the action "to bend a hand in the elbow, to open the palm, to place it around the stick, to close the palm". For a person, for example, it is more difficult to repeat an action that does not have a clearly defined goal (the movement of the index finger along the specified path) than the directed action (the movement of the finger towards the point on the table). Mirror neurons group muscle movements not by the involved muscle, but by purpose, reason and significance. Thus, they help to repeat the actions of others, not focusing on the angle of the body's inclination or the tension of the muscles. Thus, mirror neurons, according to their numerous researchers, can be the basis of imitative training: from imitation of infants to the movements of the lips of the mother before learning the language and grammar.
This is connected with another, much more controversial, but at the same time intriguing application of mirror neurons, proposed by some researchers. Mirror neurons, they say, have determined the very appearance of our ancestors.
Arguments are twofold. On the one hand, the idea of a logical, semantic analysis of reality by individual groups of cells-for example, the fact that the finger moves not just so, but toward the point-hints at the biological basis of grammar in the face of mirror neurons. But there is another impressive argument. The area of the cortex, in which the mirror neurons are found in man, lies exactly through the Broca zone: the center of speech.
The Broca zone responds not just for pronouncing words, but for abstract connections between them - that is, precisely for semantics. It is activated the same in ordinary people during the conversation, when pronouncing words to themselves, and also for deaf people using sign language. This language differs from the usual in form, but not in the internal structure - the designation of the interrelationships between objects. Like all human languages, he follows the laws of "universal grammar," proposed by Noam Chomsky.
It is quite different when a person learns an "unnatural" language. Such a language does not correspond to a universal grammar. It consists of real words, but the connections between them are invented in contradiction to all human languages: for example, denial can be denoted by the ordinal number of the word in the sentence. A person can be taught such a language, but the Broca zone will not be involved in it. It turns out that human language is just as much a biological phenomenon as a cultural one. Of all the neurons in the brain, the work of which we know something, the mirror neurons are best suited for the role of "neurons of the language."
How did the speech and what role did it play in the evolution of man? How much consciousness determined the origin of language, and how much language - or at least a set of innate semantic rules - determined the emergence of consciousness? Specialists in mirror neurons argue that the first stage in the formation of any communication should be the ability to convey meaning. Since mirror neurons - today the only found "radar of meaning", they are attributed to the central role in the evolution of the human language, and perhaps, of consciousness.
The illustrations are used in agreement with the Depositphotos photobank
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