Localization of functions in the Big Brain Hemispheres. The problem of localization of functions in the cerebral cortex Localization of the motor zone in the cerebral cortex
Morphological bases of the dynamic localization of functions in the core of the hemispheres of a large brain (centers of the cerebral cortex)
Knowledge of the localization of functions in the cerebral cortex has a huge theoretical value, as it gives an idea of \u200b\u200bthe nervous regulation of all the processes of the organism and to adapt it to the environment. It has great practical importance for the diagnosis of lesion places in the hemispheres of the brain.
The idea of \u200b\u200bthe localization of the function in the cerebral cortex is primarily connected with the concept of the cortical center. Back in 1874, Kievan Anata V. A. Betin spoke with the statement that each section of the cortex differs in the structure from other parts of the brain. This was the beginning of the teaching on the dormitory of the cerebral cortex - cytoarchitectonics (cytos - cell, architectones - build). Research by Brodman, Economo and Employees of the Moscow Institute of Brain, led by S. A. Sarkisov, managed to identify more than 50 different sections of the cortex - the cortical cyt-architectonic fields, each of which differs from others on the structure and location of the nerve elements; There is also a division of bark in more than 200 fields. Of these fields, indicated by the rooms, a special "card" of the human brain bark is compiled (Fig. 299).
According to I. P. Pavlov, the center is the brain end of the so-called analyzer. Analyzer is a nervous mechanism that is the function of which is to decompose the well-known complexity of the external and inner world into separate elements, i.e. produce analysis. At the same time, thanks to wide connections with other analyzers, synthesis, a combination of analyzers with each other and with different activities of the body occurs here. "The analyzer is a complex nervous mechanism, starting by the outer perceiving apparatus and ending in the brain." From the point of view of I. P. Pavlov, the brainstall, or the cortical end of the analyzer, has no strictly outlined boundaries, but consists of nuclear and multiple part - the theory of the nucleus and scattered elements. The "kernel" presents a detailed and accurate projection in the crust of all elements of the peripheral receptor and is necessary for the implementation of higher analysis and synthesis. "Scattered elements" are on the periphery of the nucleus and can be scattered away from it; They are carried out simpler and elementary analysis and synthesis. During the damage to the nuclear part, the scattered elements can compensate to a certain extent to compensate for the resulting the function of the nucleus, which has a huge clinical value to restore this function.
Prior to I. P. Pavlova, a motor zone was distinguished in the cortex, or motor centers, anterior central shock and sensitive zone, or sensitive centers located behind Sulcus Centralis Rolandi. I. P. Pavlov showed that the so-called motor zone corresponding to the anterior central winking, as well as other cerebral zones that perceives the area (cortical end of the motor analyzer). "The engine area is a receptor region ... this establishes the unity of the entire bark of the hemispheres."
Currently, the entire brain crust is considered as a solid perceiving surface. The bark is a set of circular ends of analyzers. From this point of view, we will consider the topography of the cortical departments of analyzers, i.e., the main perceive sections of the cortex of a large brain.
First of all, consider the cortical ends of internal analyzers.
1. The kernel of the motor analyzer, i.e., the analyzer of proprioceptive (kinesthetic) irritations emanating from bones, joints, skeletal muscles and their tendons are located in anterior central urinet (fields 4 and 6) and LOBULUS PARACENTRALIS. Motor conventional reflexes are closed here. Motorial paralysis arising from the damage to the motor zone, I. P. Pavlov explains not damage to the motorcycle effectant neurons, and the violation of the kernel of the motor analyzer, as a result of which the bark does not perceive the kinesthetic irritations and movements become impossible. Motor analyzer kernel cells are laid in the middle layers of the motor zone cortex. In the deep layers (5th, partly and 6th) there are giant Betz's pyramid cells, which are of efferent neurons that I. P. Pavlov considers both inserting neurons that bind the bark of the brain with subcortical nodes, cores of head nerves and front horns spinal cord, i.e. with motor neurons. In the front central winding, the human body, as well as in the rear, is desozed down his head. At the same time, the right motor area is associated with the left half of the body and, on the contrary, for the pyramidal paths starting from it are crossed into a part in the oblong, and part of the spinal cord. . Washing torso, larynx, pharynges are influenced by both hemispheres. In addition to the front central winding, propriceceptive impulses (muscular-articular sensitivity) come to the bark of the rear central sinking.
2. The kernel of the motor analyzer, which is related to the combined rotation of the head and eye in the opposite direction, is placed in the middle frontal winding, in the premotor region (field 8). This turn occurs during irritation of the field 17, located in the occipital share in the neighborhood with the core of the visual analyzer. Since when cutting the muscles of the eye in the bark of the brain (motor analyzer, field 8), not only pulses from the receptors of these muscles are always received, but also pulses from the retina (visual analyzer, field 17), then various visual irritations are always combined with different positions of the eyes, Installed reduction in the muscles of the eyeball.
3. The kernel of the motor analyzer, by means of which the synthesis of targeted combined movements occurs, is placed in the left (in the right-hander) of the lower dump sheer, in Gyrus Supramarginalis (deep layers of the field 40). These coordinated movements, formed on the principle of temporary connections and developed by the practice of individual life, are carried out through the connection of Gyrus Suppramarginalis with anterior central winding. Under the defeat of the field 40, the ability to move in general, but the inability to make targeted movements, act - apraxia (PRACSIA - action, practice) appears.
4. The core of the position analyzer and the head of the head is a static analyzer (vestibular apparatus) -to core of the brain is definitely not yet localized. There is reason to assume that the vestibular apparatus is projected in the same area of \u200b\u200bthe crust as the snail, i.e. in the temporal share. Thus, with the defeat of the fields 21 and 20, lying in the region of the middle and lower temporal convolutions, an ataxia is observed, i.e., an equilibrium disorder, shaking the body when standing. This analyzer, which plays a decisive role in a person's straightening, is of particular importance for the operation of pilots in the conditions of rocket aviation, since the sensitivity of the vestibular apparatus on the aircraft is much reduced.
5. The core of the pulse analyzer coming from the internally and vessels (vegetative functions) is located in the lower departments of the front and rear central soot. Centripetal impulses from the internships, vessels, smooth muscles and glands of the skin are entering this department of the cortex, from where the centrifugal paths come from for subcortictive vegetative centers.
In the premotor region (fields 6 and 8), a merge of vegetative and animal functions is performed. However, it should not be considered that only this area of \u200b\u200bthe crust affects the activities of the internships. They affect the condition of the entire bark of the hemispheres of the big brain.
Nervous impulses from the external environment of the body enter the cortical ends of the analyzers of the outside world.
1. The kernel of the auditory analyzer lies in the middle part of the upper temporal winding, on the surface facing an island - fields 41, 42, 52, where the snail is oppressed. Damage leads to a cortical deafness.
2. The core of the visual analyzer is in the occipital share - fields 17, 18, 19. On the inner surface of the occipital share, along the edges of Sulcus Calcarinus, the visual path ends in the field 17. Here, the retina of the eye is distrounded, and the visual analyzer of each hemisphere is associated with field fields and co-half of the retina of both eyes (for example, the left hemisphere is associated with the lateral half of the left eye and the medial right). When defeating the core of the visual analyzer, blindness occurs. Above the field 17 is located in the field 18, with the defeat of which the vision is saved and the visual memory is lost. Even above, there is a field 19, with the defeat of which the orientation is lost in the unusual setting.
3. The core of the olfactory analyzer is placed in the phylogenetically the most ancient part of the cortex of the brain, within the foundation of the olfactory brain - Uncus, partly Ammonov Horn (field 11).
4. The core of the taste analyzer, according to the same data, is located at the bottom of the rear central winding, close to the centers of the muscles of the mouth and language, in others - in UNCUS, in the nearest neighborhood with the cortical end of the olfactory analyzer, which explains the close relationship of the olfactory and taste sensations. It has been established that the disorder of taste occurs when the field is damaged 43.
Analyzers of smelling, taste and hearing of each hemisphere are associated with receptors of the relevant bodies of both sides of the body.
5. The core of the skin analyzer (tactile, pain and temperature sensitivity) is located in the rear central urinet (fields 1, 2, 3) and in the cortex of the upper dark area (fields 5 and 7). At the same time, the body is designed in the rear central winding upside down, so that in the upper part of it is located the projection of the lower extremities receptors, and in the bottom - the projection of the head receptors. Since animals, general sensitivity receptors are especially developed at the head end of the body, in the field of the mouth, which plays a huge role when capturing food, the person has a strong development of the mouth receptors. In this regard, the region of the latter occupies the rear central sulfur in the cortex is an exorbitantly large zone. At the same time, a person in connection with the development of a hand as a labor body increased dramatically increased receptors of touch in the skin of a brush, which has become the conname authority. Accordingly, the sections of the cortex relating to the upper limb receptors are sharply superior to the lower limb area. Therefore, if in the rear central will repose a person's figure head down (to the base of the skull) and the footsteps up (to the upper edge of the hemisphere), then you need to draw a huge face with a loosely big mouth, a big hand, especially the brush with a thumb, sharply superior, A small torso and a small leg. Each rear central convulsion is connected with the opposite part of the body due to the crossing of sensitive conductors in the dorsal and part in the oblong brain.
Private skin view - recognition of items to the touch, stereogeneration (stereos - spatial, gnosis - knowledge) - is associated with the section of the cortex of the top darker slices (field 7) Cross: the left hemisphere corresponds to the right hand, right-handed hand. With damage to the surface layers of the field 7, the ability to recognize the items to the touch, with closed eyes.
The described cortical ends of the analyzers are located in certain areas of the cerebral bark, which thus represents a "grand mosaic, a grand alarm board". On this "board" due to analyzers, signals from the external and internal environment of the body are falling. These signals, according to I. P. Pavlov, and constitute the first signaling system of reality, manifested in the form of concretely visual thinking (sensations and complexes of sensations - perception). The first signal system is also available in animals. But "In the developing animal world, an extraordinary increase in the mechanisms of nervous activity occurred in the person's phase. For an animal, validity is signaling almost exclusively only irritations and traces of them in large hemispheres, directly coming into special cells of visual, auditory and other receptors of the body. This is what and we have in yourself the impressions, sensations and ideas from the environment, both the generally enforcement, and from our social, excluding the word, audible and visible. This is the first signaling system, common with animals. But the word was the second, specially our signaling system of reality, being a signal of the first signals ... It was the word that made us people. "
Thus, I. P. Pavlov distinguishes two cortical systems: the first and second signaling systems of reality, from which the first signaling system appeared first (it is also in animals), and then the second one - it is only a person and is a verbal system. The second signal system is human thinking, which is always verbly, for the tongue is the material shell of thinking. Language is "... direct validity of thought."
By very long repetition, temporary links were formed between certain signals (audible sounds and visible signs) and the movements of the lips, the language, the muscles of the larynx, on the one hand, and with real stimuli or ideas about them, on the other. So, on the basis of the first signal system, the second appeared.
Reflecting this process of philogenesis, a person in ontogenesis is first laid the first signaling system, and then the second. For the second signal system to start functioning, child communication is required with other people and the acquisition of oral and written speech skills, which has a number of years. If the child is born a deaf or loses his hearing before he began to speak, then the oral speech that was not used, and the child remains dumb, although the sounds he can pronounce. In the same way, if a person does not teach reading and writing, he will forever remain illiterate. All this indicates the decisive effect of the environment for the development of the second signal system. The latter is associated with the activities of the entire bark of the brain, but some areas of it play a special role in the implementation of speech. These areas of the cortex are cores of speech analyzers.
Therefore, to understand the anatomical substrate of the second signaling system, it is necessary, in addition to the knowledge of the structure of the core of a large brain as a whole, also take into account the cortical ends of speech analyzers (Fig. 300).
1. Since we were a means of communication of people in the process of their joint work, then the motor analyzers of speech were developed in the immediate vicinity of the nucleus of the general motor analyzer.
Speech Articulation Motor Analyzer (Specling Analyzer) is located in the back of the bottom frontal winding (Gyrus of Gos, field 44), in close proximity to the lower motor zone department. It analyzes irritations coming from musculature participating in creating oral speech. This function is associated with the muscle analyzer of the muscles of the lip, language and larynx, located in the lower part of the front central winding, which explains the proximity of the spectavatic analyzer to the engine analyzer of the mentioned muscles. With the defeat of the field 44, the ability to produce the simplest movements of speech muscles, scream and even sing, but the possibility of pronounced words - Motor AFAZII (Phase - speech) is lost. Ahead of the field 44 is a field 45, having a relation to speech and singing. With the defeat, it arises vocal amusy - the inability to sing, make musical phrases, as well as agrammatism - the inability to compose from the words of the proposal.
2. Since the development of oral speech is associated with the hearing body, the hearing analyzer of oral speech has been developed in close proximity to the sound analyzer. Its kernel is placed in the back of the upper temporal winding, in the depths of the lateral furrow (field 42, or the center of the Wernik). Thanks to the auditory analyzer, various sound combinations are perceived by a person as words that mean various objects and phenomena and become their signals (second signals). With his help, he controls his speech and understands someone else's. With the defeat, its ability to hear sounds is preserved, but the ability to understand the words is verbal deafness, or sensory aphasia. With the defeat of the field 22 (the average third of the upper temporal winding) comes the musical deafness: the patient does not know the motives, and musical sounds are perceived as a random noise.
3. At a higher level of development, humanity learned not only to speak, but also to write. Written speech requires certain movements of the hand when the letters or other signs are drawn, which is associated with the motor analyzer (general). Therefore, the motor analyzer of the written speech is placed in the rear section of the middle frontal winding, near the front central zone (motor zone). The activity of this analyzer is associated with the analyzer of the hand necessary for the letter of learned (field 40 in the lower dark slices). In case of damage to the field 40, all types of movement are preserved, but the ability of the fine movements necessary to draw letters, words and other signs (Agrafy) is lost.
4. Since the development of written speech is connected with the organ of view, then in close proximity to the auditorium, a visual writing analyzer was developed, which, naturally, is associated with Sulcus Calcarinus, where the general visual analyzer is placed. The visual writing analyzer is located in the lower dump shelter, with Gyrus Angularis (field 39). In case of damage to the field 39, vision is preserved, but the ability to read (Alexy) is lost, i.e., analyze the written letters and put the words and phrases from them.
All speech analyzers are laid in both hemispheres, but develop only on the one hand (in the right-hander - left, left-handed - right) and functionally turn out to be asymmetric. This link between the motor analyzer (labor body) and speech analyzers is due to the close relationship between labor and the speech, which has decisively affecting the brain development.
"... work, and then with him ai-part speech ..." led to the development of the brain. This bond is also used in therapeutic purposes. Under the defeat of the speech motor analyzer, the elementary motor ability of speech muscles is maintained, but the possibility of oral speech is lost (motor aphasia). In these cases, it is sometimes possible to restore the speech by a long exercise of the left hand (in the right-hander), the work of which favors the development of the ridiculous right-hand core of the spectavatic analyzer.
Oral and written speech analyzers perceive verbal signals (as I. P. Pavlov says - signals of signals, or second signals), which accounts for a second signaling system of reality, manifested in the form of abstract distracting thinking (general representations, concepts, conclusions, generalizations), which It is only characteristic of a person. However, the morphological basis of the second signal system is not only the specified analyzers. Since the function of speech is phylogenetically the youngest, it is the least localized. She is inherent in the whole crust. Since the bark is growing along the periphery, the most surface layers of the cortex are related to the second signaling system. These layers consist of a large number of nerve cells (100 billion) with short processes, thanks to which the possibility of an unlimited circuit function is created, wide associations, which is the essence of the activity of the second signal system. In this case, the second signal system is not functioning separately from the first, but in a close connection with it, more precisely, based on it, since the second signals may occur only if there are first. "The main laws established in the first signal system should also manage the second, because it is the work of the same nervous tissue."
The teaching of I. P. Pavlova about two signaling systems gives a materialistic explanation of human mental activity and constitutes the natural science basis of the theory of reflection V. I. Lenin. According to this theory, in our consciousness in the form of subjective images, an objective real world is reflected, existing independently of our consciousness.
The feeling is a subjective image of an objective world.
In the receptor, external irritation, such as light energy, turns into a nervous process, which becomes a feeling in the core of the brain.
The same amount and quality of energy, in this case, the light, in healthy people will cause a green-color feeling in the cortex (subjective image), and in a dalton patient (thanks to a different structure of the retina) - a feeling of red.
Consequently, light energy is an objective reality, and the color is a subjective image, reflected in our consciousness, depending on the device of the sense organ (eyes).
So, from the point of view of the Leninsky theory of reflection, the brain can be characterized as an organ of reflection of reality.
After all of the stated structure of the central nervous system, human signs of the brain structure can be noted, that is, the specific features of the structure of it, distinguishing a person from animals (Fig. 301, 302).
1. The predominance of the brain over the dorsal. So, in predatory (for example, the cat) brain is 4 times heavier than the dorsal, in primates (for example, Macakka) - 8 times, and in humans - 45 times (the weight of the spinal cord is 30 g, head - 1500 g) . In the wound, the spinal brain in weight is in mammals 22-48% of the brain weight, the gorilla - 5-6%, in humans - only 2%.
2. Brain weight. In absolute weight of the brain, a person does not occupy the first place, since large animal brains are harder than a person (1500 g): Dolphin - 1800 g, at an elephant - 5200 g, in China - 7000 in order to open the true brain weight relationship By the weight of the body, recently began to determine the "square brain pointer", i.e., the product of the absolute weight of the brain to relative. This pointer allowed to highlight a person from the entire animal world.
So, in rodents it is 0.19, in predatory - 1.14, in vehicles (dolphin) - 6.27, in human monkeys - 7.35, at the elephants - 9.82 and, finally, a person - 32 0.
3. The predominance of the cloak over the brain barrel, i.e., the new brain (NEENCEPHALON) above the old (Palencephalon).
4. The highest development of the frontal lobe of the big brain. According to Brodman, the frontal lobe drops a round account at the lower monkeys 8-12% of the entire surface of the hemispheres, anthropoid monkeys - 16%, in a person - 30%.
5. The predominance of a new bark of a large brain hemispheres over old (see Fig. 301).
6. The predominance of the bark over the "feeding", which in humans achieves maximum numbers: the bark is, according to the range, 53.7% of the total volume of the brain, and the basal kernels are only 3.7%.
7. Farwood and gyrus. The grooves and gyruses increase the area of \u200b\u200bthe cortex of the gray matter, so the larger the core of the large brain, the greater the brain folding. The increase in folding is achieved by the large development of small furrows of the third category, the depth of the furrow and their asymmetric location. None of the animal at the same time such a large number of grooves and convulsions, while so deep and asymmetrical as in humans.
8. The presence of a second signal system, the anatomical substrate of which is the most surface layers of the brain bark.
Summing up the outlined, it can be said that the specific features of the human brain structure that distinguish it from the brain of the most highly developed animals are the maximum predominance of young parts of the central nervous system over old: brain - over the dorsal, raincoat - above the barrel, a new bark - above the old, Surface cerebral layers - over deep.
In the cerebral cortex distinguish areas - Bodman fields
The 1st zone is moving - represented by the central winding and the frontal zone in front of it - 4, 6, 8, 9 of the Bodman fields. With its irritation - various motor reactions; With its destruction - disorders of motor functions: adamina, paresis, paralysis (respectively - weakening, sharp decline, disappearance).
In the 50s, the twentieth century was installed that in the motor zone, various muscle groups are presented unequal. The muscles of the lower limb - in the upper section of the 1st zone. The muscles of the upper limb and head - in the lower section of the 1st zone. The largest square is occupied by the projection of the mimic muscles, muscles of the tongue and small muscles of the brush hand.
The 2nd zone is sensitive - sections of the cerebral cortex for the central furrow (1, 2, 3, 4, 5, 7 of the fields of Brodman). In case of irritation of this zone - sensations arise, when it is destroyed - loss of skin, proproice, interimensitivity. Highspothesia is a decrease in sensitivity, anesthesia - loss of sensitivity, paresthesia - unusual sensations (goosebumps). The upper sections of the zone are the skin of the lower extremities, genital organs. In the lower departments - leather of the upper limbs, head, mouth.
The 1st and 2nd zones are closely related to each other in functionality. In the motor zone, many afferent neurons receiving pulses from proproporeceptors are motor-axes. In the sensitive zone, many motor elements are sensorotor zones - responsible for the occurrence of pain.
The 3rd zone is a visual zone - the occipital region of the cerebral cortex (17, 18, 19 of the Bodman fields). When destroying 17 fields - loss of visual sensations (cork blindness).
Different sections of the retina are unenocomy are projected into 17 field of Brodman and have a different location during point destruction 17 fields falls the vision of the environment, which is projected to the corresponding sections of the retina. Under the defeat of the 18 fields of Brodman, the functions associated with the recognition of the visual image suffer and violates the perception of the letter. Under the defeat of the 19th field of Brodman - various visual hallucinations arise, the visual memory and other visual functions are suffering.
4th - Zone Hearing - temporal area of \u200b\u200bthe cerebral cortex (22, 41, 42 fields of Brodman). With damage to 42 fields - the sound recognition feature is broken. If 22 fields are destroyed - auditory hallucinations arise, violation of hearing indicative reactions, musical deafness. When destroying 41 fields - Cork deafness.
The 5th zone is olfactory - located in the pear-shaped urinet (11 field of Brodman).
6th zone - taste - 43 Brodman field.
The 7th zone is a speech zone (Jackson - a speech center) - most people (right-handed) are located in the left hemisphere.
This zone consists of 3 departments.
Rachatial center of Brock - located at the bottom of the frontal view of the muscles of the language. During the defeat of this area - motor aphasia.
The Touch Center Wernika is located in the temporal area - is associated with the perception of oral speech. During the defeat, there is a sensory aphasia - a person does not perceive oral speech, the pronunciation suffers, as the perception of his own speech is disturbed.
The center of perception of written speech - is located in the visual zone of the cerebral cortex - 18 field of Brodman. Similar centers, but less developed, there are in the right of hemisphere, the degree of their development depends on the blood supply. If left-hander is damaged by the right hemisphere, the speech function suffers to a lesser extent. If children are damaged to the left hemisphere, then its function takes the right. In adults, the ability of the right hemisphere to reproduce speech functions - is lost.
The meaning of various sections of the bark of the hemisphey
brain.
2. Motor functions.
3. Functions of the skin and propriocepital
sensitivity.
4. Hearing functions.
5. Summary functions.
6. Morphological foundations localization of functions in
cerebral core.
Motor analyzer core
The kernel of the auditory analyzer
Core of the visual analyzer
The core of the taste analyzer
Core of the skin analyzer
7. Bioelectric brain activity.
8. Literature.
The value of various sections of large bark
Hemispheres of the brain
From a long time, between scientists there is a dispute about the location (localization) of the sections of the cerebral cortex associated with various functions of the body. A wide variety of and mutually opposite points of view were expressed. Some believed that each function of our body corresponds to a strictly defined point in the cerebral cortex, others denied the presence of any centers; They attributed any reaction to the whole crust, considering it entirely unequivocal in functionality. The method of conditional reflexes was given the opportunity to I. P. Pavlov to find out a number of obscure issues and develop a modern point of view.
There are no strictly fractional localization of the cities in the cerebral cortex. This follows from experiments on animals, when after the destruction of certain sections of the bark, for example, the motor analyzer, after a few days the neighboring sites take on the function of the destroyed section and the movement of the animal are restored.
This ability of the cortical cells to replace the function of the precipitated areas is associated with a large plasticity of the cerebral cortex.
I. P. Pavlov believed that individual bark areas have different functional significance. However, there are no strictly defined boundaries between these areas. Cells of one region are moving to neighboring areas.
Figure 1. Communication scheme of bark departments with receptors.
1 - spinal or oblong brain; 2 - intermediate brain; 3 - brain bark
In the center of these areas there are clusters of the most specialized cells, the so-called analyzer cores, and on the periphery-less specialized cells.
In the regulation of the functions of the body, there are no strictly outlined some points, but many nervous elements of the crust.
Analysis and synthesis of incoming impulses and the formation of a response to them is carried out significantly large areas of the crust.
Consider some areas having mainly this or that value. The schematic location of the location of these areas is shown in Figure 1.
Motor functions. The cortical department of the motor analyzer is mainly in the anterior central ispuncture, the Kepende from the central (Roland) groove. In this area there are nervous cells, with the activities of which all the movements of the body are associated.
The processes of large nerve cells located in deep layers of the cortex are descended into the oblongable brain, where the significant part of them is crossed, that is, it turns on the opposite direction. After the transition, they are lowered along the spinal cord, where the rest is crossed. In the front horns of the spinal cord, they come into contact with self-engined nerve cells. Thus, the excitation that occurred in the crust comes to the motor neurons of the front horns of the spinal cord and then on their fibers goes to the muscles. Due to the fact that in oblong, and in part and in the spinal cord, the transition (crossroads) of motorways on the opposite direction, the excitation that occurred in the left hemisphere of the brain goes into the right half of the body, and pulses from the right hemisphere come to the left half of the body. That is why hemorrhage, wound or any other defeat of one side of the large hemispheres entails a violation of muscle activity of the opposite half of the body.
Figure 2. Scheme of individual areas of the cortex of large hemispheres of the brain.
1 - Motor region;
2 - area of \u200b\u200bskin
and propriorasective sensitivity;
3 - visual region;
4 - hearing area;
5 - flavoring area;
6 - olfactory area
In the anterior central gyrus, the centers innervating different muscle groups are located in such a way that at the top of the motor area there are centers of lower limb movements, then below the center of the muscles of the body, even below the center of the front limbs and, finally, below all centers of the head muscles.
Centers of different muscle groups are presented unequal and occupy uneven areas.
Functions of skin and proprioceptive sensitivity. The area of \u200b\u200bthe skin and propriceceptive sensitivity in humans is predominantly behind the central (Roland) groove in the rear central urinet.
The localization of this area in humans can be installed by the method of electrical irritation of the cortex of the brain during operations. Irritation of various sections of the bark and the simultaneous survey of the patient about the sensations that it experiences, make it possible to make a fairly clear idea of \u200b\u200bthe specified area. With the same area associated with the so-called muscular feeling. The pulses arising in the propriate receptors in the joints, muscle tendons, are predominantly in this bark department.
The right hemisphere perceives impulses going on centripetal fibers mainly with the left, and the left hemisphere is predominantly with the right half of the body. This explains the fact that the defeat, for example, the right hemisphere will cause a sensitivity disturbance predominantly.
Hearing functions. The auditory area is located in the temporal share of the bark. When removing the temporal fractions, complex sound perception is disturbed, since the possibility of the analysis and synthesis of sound perceptions is disturbed.
Summary functions. The auditorium is in the occipital share of the cerebral cortex. When removing the occipital fraction of the brain, the dog comes a loss of vision. The animal does not see, stumps on items. Only pupil reflexes in humans are preserved. A violation of the visual region of one of the hemispheres causes half the vision of each eye. If the defeat touched the visual region of the left hemisphere, then the functions of the nasal part of the retina of one eye and the temporal part of the retina of another eye drop out.
Such a feature of lesion of vision is connected with the fact that the visual nerves along the way to the cortex are partially crossed.
The morphological foundations of the dynamic localization of functions in the core of the hemispheres of a large brain (centers of the cerebral cortex).
Knowledge of the localization of functions in the cerebral cortex has a huge theoretical value, as it gives an idea of \u200b\u200bthe nervous regulation of all the processes of the organism and to adapt it to the environment. It has great practical importance for the diagnosis of lesion places in the hemispheres of the brain.
The idea of \u200b\u200bthe localization of functions in the cerebral cortex is primarily connected with the concept of the cortical center. Back in 1874, Kievan Anata V. A, Betz spoke with the statement that each participation in the bark differs in the structure from other parts of the brain. This was the beginning of the teaching on the dormitory of the cerebral cortex - cytoarchitectonics (cytos - cell, architectones - build). Currently, it was possible to identify more than 50 different sections of the crust of cortical cytoarchitectonic fields, each of which differs from others in the structure and location of nerve elements. Of these fields, indicated by the rooms, a special map of human brain bark is composed.
P 
o I.P. Pavlov, the center is the brain end of the so-called analyzer. Analyzer is a nervous mechanism that is the function of which is to decompose the well-known complexity of the external and inner world into separate elements, i.e. produce analysis. At the same time, thanks to wide connections with other analyzers, the synthesis of analyzers with each other and with different activities of the body occurs here.
Figure 3. Map of cytoarchitoneic fields of the human brain (according to the Institute of MEGEA AMN USSR) at the top - the upper-tapeth surface, lower-medial surface. Explanation in the text.
Currently, the entire brain crust is considered as a solid perceiving surface. The bark is a set of circular ends of analyzers. From this point of view, we will consider the topography of the cortical departments of analyzers, i.e., the main perceive sections of the cortex of a large brain.
First of all, consider the tapered ends of the analyzers that perceive irritations from the inner environment of the body.
1. The kernel of the motor analyzer, i.e., analyzer of proprioceptive (kinesthetic) irritation emanating from bones, joints, skeletal muscles and their tendons, is in a precentral urinet (fields 4 and 6) and LOBULUS PARACENTRALIS. Motor conventional reflexes are closed here. Motorial paralysis arising from the damage to the motor zone, I. P. Pavlov explains not damage to the motorcycle effectant neurons, and the violation of the kernel of the motor analyzer, as a result of which the bark does not perceive the kinesthetic irritations and movements become impossible. Motor analyzer kernel cells are laid in the middle layers of the motor zone cortex. In the deep layers (V, partly VI) there are gigantic pyramidal cells, which are of efferent neurons that I. P. Pavlov examines both insert neurons connecting the bark of the brain with subcortical nuclei, cerpent nerve cores and the front horns of the spinal cord, that is . with motor neurons. In a prechangeful winding, the human body, as well as in the rear, is properly head. At the same time, the right motor area is associated with the left half of the body and, on the contrary, for the pyramidal paths starting from it are crossed by part in the oblong, and part of the spinal cord. Muscles of the body, larynx, pharynges are under the influence of both hemispheres. In addition to pre-centered winding, propriceceptive impulses (muscular-articular sensitivity) come to the cera of post-central overhang.
2. The kernel of the motor analyzer, having-related to the combined rotation of the head and eye in the opposite direction, is placed in the middle frontal winding, in the premotor region (field 8). This turn occurs during irritation of the field 17, located in the occipital share in the neighborhood with the core of the visual analyzer. Since when cutting the muscles of the eye in the bark of the brain (Motor Analyzer, Field 8), not only pulses from the receptors of these muscles are always received, but also impulses from the eet-cart (visual analyzer, field 77), then various visual irritations are always combined with different positions Eye, installed abbreviation of the muscles of the eyeball.
3. The kernel of the motor analyzer, by means of which the synthesis of targeted complex professional, labor and sports movements occurs, is placed in the left (in the right hand) of the lower dark lurch, in Gyrus Supramarginalis (deep layers of field 40). These coordinated movements, formed on the principle of temporary ties and developed by the practice of individual life, are carried out through the connection of Gyrus Supramarginalis with a precentral winding. Under the defeat of the field 40, the ability to move in general, but the inability to make targeted movements, act - apraxia (PRACSIA - action, practice) appears.
4. The core of the position analyzer and the head of the head is a static analyzer (vestibular apparatus) in the brain core is definitely not yet localized. There is reason to assume that the vestibular apparatus is projected in the same area of \u200b\u200bthe crust as the snail, i.e. in the temporal share. Thus, during the defeat of fields 21 and 20 lying in the region of the middle and lower temporals, an ataxia is observed, that is an equilibrium disorder, shaking the body when standing. This analyzer, which plays a decisive role in a person's straightening, is of particular importance for the operation of pilots in the conditions of reactive aviation, since the sensitivity of the vestibular apparatus by the plane is significantly reduced.
5. The core of the pulse analyzer coming from the internally and vessels is located in the lower departments of the front and rear central convulsions. The centripetal impulses from the internships, vessels, involuntary muscles and the skin glands go to this bark department, from where the centrifugal paths are departed to subcortex vegetative centers.
In the premotor region (fields 6 and 8) there is a merge of vegetative functions.
Nervous impulses from the external environment of the body enter the cortical ends of the analyzers of the outside world.
1. The kernel of the auditory analyzer lies in the middle part of the upper temporal winding, on the surface facing an island, - fields 41, 42, 52, where the snail is projected. Damage leads to deafness.
2. The core of the visual analyzer is in the occipital share - fields 18, 19. On the inner surface of the occipital share, along the edges of Sulcus Icarmus, the visual path ends in the field 77. The retina's retina is designed here. With the damage to the core of the visual analyzer comes blindness. Above the field 17 is located in the field 18, with the defeat of which the vision is saved and the visual memory is lost. Even above, there is a field with a defeat of which the orientation in the unusual shelf is lost.
3. The core of the taste analyzer, according to the same data, is located in the lower post central urina, close to the centers of the muscles of the mouth and language, in others - in the nearest neighborhood with the cortical end of the olfactory analyzer, which explains the close relationship of the olfactory and taste. It has been established that the disorder of taste occurs when the field is damaged 43.
Analyzers of smelling, taste and hearing of each hemisphere are associated with receptors of the relevant bodies of both sides of the body.
4. The core of the skin analyzer (tactile, pain and temperature sensitivity) is located in a post-central urinet (fields 7, 2, 3) and in the top of the parietal area (fields 5 and 7).
Private skin view - recognition of items to the touch - stereogeneration (stereos - spatial, gnosis - knowledge) is associated with the section of the cortex of the upper dark slices (field 7) Cross: the left hemisphere corresponds to the right hand, right-handed hand. With damage to the surface layers of the field 7, the ability to recognize the items to the touch, with closed eyes.
Bioelectric brain activity.
The discharge of brain biopotentials - electroencephalography-gives an idea of \u200b\u200bthe level of physiological activity of the brain. In addition to the method of electroencephalography, the recording of bioelectric potentials, use the method of encephaloscopy-registration of vibrations of the brightness of the glow of a plurality of brain points (from 50 to 200).
The electroencephalogram is an integrative space-time indicator of spontaneous electrical activity of the brain. It distinguishes the amplitude (scope) of oscillations in microvolts and the frequency of oscillations in Hertz. In accordance with this, four types of waves differ in the electroencephalogram: -, -, - and -rhythms. For -rhythm, frequencies are characterized in the range of 8-15 Hz, with an amplitude of oscillations of 50-100 μV. It is recorded only in humans and higher monkeys in a state of wakefulness, with closed eyes and in the absence of external stimuli. Spectative stimuli inhibit -rhythm.
Separate people with lively visual imagination, -rhythm may generally be absent.
For the activity of the brain, it is characteristic (-rhythm. These are electric waves with an amplitude of 5 to 30 μV and a frequency of 15 to 100 Hz, it is well recorded in the frontal and central regions of the brain. During sleep, -rhythm appears. It is also observed with negative emotions, painful states. The frequency of potentials -rhythm from 4 to 8 Hz, amplitude from 100 to 150 μV during sleep appears and -rhythm - slow (with a frequency of 0.5-3.5 Hz), high amplitude (up to 300 μV ) fluctuations in the electrical activity of the brain.
In addition to the considered types of electrical activity, a person registers an e-wave (wave of an irritant) and spindle-shaped rhythms. Wave waiting is registered when performing conscious, expected actions. It precedes the appearance of an expected stimulus in all cases, even with a repeated repetition. Apparently, it can be considered as the electroencephalographic correlation of the action acceptor, which ensures the prediction of the results of the action before it is completed. Subjective readiness to respond to the action of the incentive strictly in a certain way is achieved by the psychological installation (D. N. Finds). The spindle-shaped rhythms of non-permanent amplitude, with a frequency of 14 to 22 Hz, appear during sleep. Various forms of activity of activity lead to a significant change in the rhythms of the bioelectric activity of the brain.
When mental work, it is strengthened by rhythm, -rhythm disappears. With muscle work of a static character, the desynchronization of the electrical activity of the brain is observed. Fast fluctuations with low amplitudes appear. The time of dynamic operation of PE- The riot of desynchronized and synchronized activity is observed accordingly at the moments of robust and recreation.
The formation of the conditional reflex is accompanied by the desynchronization of the wave activity of the brain.
Desynchronization of waves occurs when moving from sleep to wakefulness. In this case, the spindle-shaped sleep rhythms are replaced.
-rhythm, the electrical activity of the reticular formation increases. Synchronization (the same in phase and the direction of the wave)
characteristic for the brake process. It is most distinctly expressed when it is turned off the reticular formation of the stem portion of the brain. The waves of the electroencephalogram, according to the majority of researchers, are the result of the summation of brake and exciting postsynaptic potentials. The electrical activity of the brain is not a simple reflection of metabolic processes in the nervous tissue. It is established, in particular, that in the impulse activity of individual accumulations of nerve cells, signs of acoustic and semantic codes are found.
In addition to the specific nuclei of Talamus, associative nuclei arise and develops, having connections with neocortex and determining the development of the final brain. The third source of afferent influences on the bark of large hemispheres is a hypothalamus, which plays the role of a supreme regulatory center for vegetative functions. In mammals, phylogenetically more ancient departments of the front hypothalamus are associated with ...
The formation of conditional reflexes is hampered, memory processes are violated, the selectivity of reactions is lost and their unreasonable gain is noted. The big brain consists of almost identical half - right and left hemispheres, which are connected by a corn body. Commissioning fibers bind symmetric bark zones. Nevertheless, the bark of the right and left hemispheres are not symmetric not only outwardly, but also ...
The approach to the assessment of the mechanisms of work of the highest departments of the brain using conditioned reflexes was so successful that Pavlov was allowed to create a new section of physiology - "physiology of higher nervous activity", science on the mechanisms of work of large hemispheres of the brain. Unconditional and conditioned reflexes The behavior of animals and a person is a complex system of interrelated ...
In the core of the big brain there is an analysis of all irritations that come from the surrounding outer and interior. The greatest number of afferent pulses enters the cells of the 3rd and 4th layers of the large brain cortex. In the core of the big brain there are centers governing the execution of certain functions. I. P. Pavlov considered the bark of the big brain as a combination of the conversion ends of the analyzers. Under the term "analyzer" means a complex complex of anatomical structures, which consists of a peripheral receptor (perceive) apparatus, conductors of nerve impulses and the center. In the process of evolution, the localization of functions in the core of the big brain occurs. The cortical end of the analyzers is not some kind of outlined zone. In the core of a large brain distinguish the "core" of the sensory system and "scattered elements". The core is a portion of the location of the largest number of cortex neurons in which all the structures of the peripheral receptor are accurately projected. The scattered elements are located near the kernel and at various distances from it. If the nucleus is carried out by the highest analysis and synthesis, then in scattered elements - simpler. At the same time, the zones of "scattered elements" of various analyzers do not have clear boundaries and lay down on each other.
Functional characteristics of the cortical zones of the frontal share.In the field of precentral windows, the cortical core of the motor analyzer is located. This area is also called sensorobic crust. Here comes part of the afferent fibers from the Talamus, carrying propriceceptive information from the muscles and the joints of the body (Fig. 8.7). It also starts downward paths to the brain barrel and spinal cord, ensuring the possibility of conscious regulation of movements (pyramid paths). The defeat of this area of \u200b\u200bthe cortex leads to paralysis of the opposite half of the body.
Fig. 8.7. Somatotopic distribution in precentral urge
In the rear third of the middle frontal winding is a letter of writing. This bark zone gives projection to the nuclei of the ice cranial cranial nerves, as well as with the help of cortical-cortical links, communicated with the center of view in the occipital share and the center of hand and neck muscles management center in a precentral urinet. The defeat of this center leads to violations of the skills of the letter under the control of view (Agrafa).
The zone of the lower headquarters is a spectavatic center (Brock Center). It has a pronounced functional asymmetry. When it is destruction in the right hemisphere, the ability to regulate the timbre and intonation is lost, it becomes monotonous. With the destruction of the speech margin of the left, the speech articulation is irreversibly disturbed up to the loss of the ability to the self-partition speech (aphasia) and singing (amusion). With partial disorders, agrammatism may be observed - the inability to properly build phrases.
In the field of the front and middle third, the top, middle and partially lower frontal zone, there is an extensive front associative zone of the bark, which provides programming of complex forms of behavior (planning of various forms of activity, decision-making, analysis of the results obtained, volitional reinforcement, correction of the motivational hierarchy).
The region of the frontal pole and the medial frontal windows is timed to the regulation of the activity of emotiogenic areas of the brain, which are included in the limbic system, is related to control over psycho-emotional states. Violations in this area of \u200b\u200bthe brain can lead to changes to the fact that it is customary to call the "personality structure" and to affect the nature of man, its value orientations, intellectual activity.
The orbital area contains centers of an olfactory analyzer and are closely connected in an anatomical and functional plan with a limbic brain system.
The functional characteristic of the cortical dump areas.In the post-central urinet and the upper dark slices there is a cortical center of the general sensitivity analyzer (pain, temperature and tactile), or somatosensory bark. Representation of various parts of the body in it, as in a precentral urge, built on a somatotopic principle. This principle assumes that parts of the body are projected onto the surface of the furrows in those topographic relations they have in the human body. However, the representation of different parts of the body in the brain core differs significantly. The greatest representation has those areas (brush hands, head, especially language and lips), which are associated with complex movements of the type of writing, speech, etc. Body disorders in this area lead to partial or complete anesthesia (loss of sensitivity).
The lesions of the cortex in the field of the upper dark slices lead to a decrease in pain sensitivity and impaired stereogeneration - recognition of items to the touch without vision.
In the lower dump, the center of Praksia, regulating the ability to carry out the formation of actions that require special learning is located in the lower dumping slicer in the region of Načrayeva. From here also originates a significant number of downstream fibers, following the paths, governing conscious movements (pyramid paths). This area of \u200b\u200bthe parietal bark using cortical-corous bonds closely interacts with the bark of the frontal share and with all the sensory zones of the rear half of the brain.
In the angular overwhelming of the parietal lobe is the visual (optical) center of speech. His damage leads to the impossibility of understanding the read text (Alexy).
Functional characteristics of the cortical zaselels.In the area of \u200b\u200bthe spur furrows there is a cortical center of the visual analyzer. Its damage leads to blindness. In case of violations in the neighboring boring parts of the bark in the area of \u200b\u200bthe occipital pole on the medial and lateral surfaces of the share, the loss of visual memory may occur, the ability to navigate in an unfamiliar situation, the functions associated with binocular vision (the ability through vision is evaluated to evaluate the shape of the objects, the distance to them , correctly proportionate in the space of the movement under the control of the vision, etc.).
The functional characteristics of the cortical zone of temporal share.In the region of the upper temporal winding in the depths of the side groove, there is a cortical center of the auditory analyzer. His damage leads to deafness.
In the rear third of the upper temporal winding lies the auditory center of speech (center of the Wernik). Injuries in this area lead to the inability to understand oral speech: it is perceived as noise (sensory aphasia).
In the region of the middle and lower temporal, the cortical representation of the vestibular analyzer is located. Damage to this area leads to equilibrium disorders when standing and reduced the sensitivity of the vestibular apparatus.
The functional characteristic of the cortical zones of the island lobe.
Information relating to the functions of the island fraction, contradictory and insufficient. There is evidence that the front of the edge of the island is related to the analysis of olfactory and taste sensations, and the rear part - to the processing of somatosensory information and the auditory perception of speech.
Functional characteristics of the limbic system. Lymbic system - The combination of a number of brain structures includes a waist ulus, shells, gear and paragipocampal gyms, etc. Participates in the regulation of the functions of internal organs, smelling, instinctive behavior, emotions, memory, sleep, wakefulness, etc.
The waist and paragipocampal winding is directly related to the limbic brain system (Fig. 8.8 and 8.9). It is controlled by a complex of vegetative and behavioral psycho-emotional reactions to the external impact. In Paragipocampal Izvilina and Crochet there is a cortical representation of taste and olfactory analyzers. At the same time, Hippocampus plays an important role in learning: mechanisms of short-term and long-term memory are associated with it.
Fig. 8.8. Medical brain surface
Basal (subcortical central) nuclei -the accumulations of the gray substance forming separately lying kernels that are closer to the base of the brain. These include a striped body that is in the lower vertebrates the prevailing mass of the hemispheres; Fence and almond-shaped body (Fig. 8.10).
Fig. 8.9. Lymbic system
Fig. 8.10. Basal ganglia
The striped body consists of a taper and lentilicular nuclei. The gray substance of the tail and lentilicular nuclei alternates with the strata of the white substance, which led the general name of this group of subcortical nuclei - a striped body.
The tail core is located laterally and above the Talamus being separated from it by the terminal strip. The taper kernel has a head, body and tail. Lental core is located laterally tailed. The white substance layer is an inner capsule, separates a lental core from the taleste and from Talamus. In a lentitrician core, a pale ball (medial) and shell (laterally) are distinguished. The outer capsule (narrow strip of white substance) separates the shell from the fence.
The tail of the core, the shell and a pale ball control the complex theordinated automated movements of the body, control and maintain the skeletal muscle tone, and are also the highest regulation center of such vegetative functions, such as heat-product and carbohydrate exchange in body muscles. During damage to the shell and a pale ball, slow stereotypical movements may be observed (athettos).
The nuclei of a striped body belongs to an extrapyramidal system involved in controlling movements, regulation of muscle tone.
The fence is the vertical plate of the gray substance, the lower part of which continues in the substance of the front reinforced plate on the base of the brain. The fence is located in the white substance of the hemisphere laterally lentilicular kernel and has numerous connections with the crust of large hemispheres.
The almond-shaped body occurs in the white substance of the hemisphere of the hemisphere, by 1.5-2 cm for the star from its temporal pole, through the nuclei there is a connection with the cortex of a large brain, with the structures of the olfactory system, with the hypothalamus and the cerebral cores that control the vegetative functions of the body. Its destruction leads to aggressive behavior or apatic, sluggish state. Due to its relations with the hypothalamus, the almond-shaped body affects the endocrine system, as well as on reproductive behavior.
The hemispheres include the inner capsule and fibers passing through brain spikes (corn body, front spike, spike variety) and guide to the crust and basal nuclei, arch, as well as fiber systems connecting the sections of the cortex and subcortex centers within one half of the brain (Hemisphere).
I and II side ventricles.High brain semi-guns are the side ventricles (I and II), located in the thickness of the white substance under the corn body. Each ventricle consists of four parts: the front rog lies in the frontal, the central part is in the dark, the rear rog is in the occipital and lower rog - in the temporal share (Fig. 8.11).
The front horns of both ventricles are separated from each other with two plates of the transparent partition. The central part of the lateral ventricle bends on top of the Talamus, forms an arc and moves the back - in the rear rogue, a book in the bottom horn. In the central part and the lower horn of the side ventricular, a vascular plexus is given, which through the interventricular hole is connected to the vascular plexus of the third ventricle.
Fig. 8.11. Brain ventricles:
1 - left hemisphere of the brain, 2 - side ventricles, 3 - the third ventricle, 4 - plumbing of the mid brain, 5 - the fourth ventricle, 6 - cerebellum, 7 - entrance to the central spinal cord channel, 8 - spinal cord
The ventricular system includes paired C-shaped cavities - side ventricles with their front, bottom and rear horns, stretching, respectively, in frontal shares, into temporal fractions and in the occipital shares of the hemispheres of the brain. About 70% of the entire cerebrospinal fluid is secreted by the vascular plexus of the walls of the side ventricles.
From the side ventricles, the fluid passes through the interventricular holes in the alcoholic cavity of the third ventricle, located in the sagittal plane of the brain and separating two symmetrical half of the thalamus and the hypothalamus. The third ventricular cavity is connected by a narrow channel - the medium brain water supply (Silviev water supply) with the cavity of the fourth ventricle. The fourth ventricle with several channels (apertures) is reported to the subparent spaces of the head and spinal cord.
Intermediate brain
The intermediate brain is located under the corrosive body, consists of a thalamus, epitulamus, metatalamus and hypothalamus (Fig. 8.12, see Fig. 7.2).
Talamus(Spectator) - a pair, ovoid shape, is mainly formed by gray matter. Talamus is a subcortex center of all kinds of sensitivity. The medial surface of the right and left thalamus, addressed to each other, form the side walls of the intermediate brain cavity - III ventricle, they are interconnected by an interstilacy battle. Talamus contains a gray substance consisting of clusters of neurons that form the thalamus kernels. The kernels are separated by thin layers of white substance. About 40 cores of Talamus were investigated. The main cores are the front, medial, rear.
Fig. 8.12. Brain departments
Epitalaimusincludes a cisheloid body, leashes and triangles of leashes. Blue-shaped body, or epiphysis, which is an iron of internal secretion, as if suspended on two leashes, interconnected with a spike and talamus connected through triangles of leashes. In the triangles, the kernels belonging to the olfactory analyzer are laid. In an adult, the average length of the epiphyse is ~ 0.64 cm, and a mass ~ 0.1 g. Metatalamus formed by paired medial and lateral crankshafts behind each Talamus. Medial crankshaft is behind the Talamus pillow, it is along with the bottom hills of the medium brain roof plate (quadruple) by the subcortex center of the auditory analyzer. Lateral - Located a book from the pillow, it together with the top hills of the roof plate is a subcortex center of the visual analyzer. The core of the crankshafts are associated with the cortical centers of optic and auditory analyzers.
Hypothalamus, Presenting a ventral part of the intermediate brain, there is a krenon from the legs of the brain and includes a number of structures that have different origins - from the final brain, the visual part is formed (visual crossing, a visual tract, a gray borgon, funnel, neurohypophysis); From the intermediate - the olfactory part (the deputyid bodies and the actual subtalamory area - subburo) (Fig. 8.13).
Figure 8.13. Basal nuclei and intermediate brain
The hypothalamus is the center of the regulation of endocrine functions, it combines the nerve and endocrine regulatory mechanisms into the total neuroendocrine system, coordinates the nerve and hormonal mechanisms for regulating the functions of the internal organs. In the hypothalamus there are neurons of the usual type and neurosecretory cells. The hypothalamus forms a single functional complex with a hypophysia, in which the first plays the regulatory, and the second effector role.
In the hypothalamus, more than 30 pairs of cores. Large neurosecrete cells of the suprasoptic and paraventricular nuclei of the front hypothalamic region produce neurospets of peptide nature.
In the medial hypothalamus, neurons occur, which perceive all changes occurring in the blood and the spinal fluid (temperature, composition, hormone content, etc.). Medial hypothalamus is also associated with the lateral hypothalamus. The latter has no nuclei, but has bilateral connections with the overlying and underlying brain departments. Medial hypothalamus is a link between nervous and endocrine systems. In recent years, enkephalins and endorphins (peptides), which have a morphine-like action are isolated from the hypothalamus. They believe that they are involved in the regulation of behavior and vegetative processes.
Kepende from the rear reinforced substance lie two small spherical shape of the mastoid bodies formed by gray substance covered with a thin layer of white. The kernels of the deputyid bodies are subcortex centers of an olfactory analyzer. Kepened from the marshide bodies is a gray borgon, which is in front of the visual crossroads and the visual tract, it is a thin plate of the gray matter at the bottom of the III of the ventricle, which is elongated down the book and the shock and forms a funnel. The end of it goes into pituitary - Iron of domestic secretion located in the pituitary fossa of the Turkish seat. In the gray bug, the kernels of the autonomic nervous system are locked. They also have an impact on human emotional reactions.
A part of the intermediate brain located below the Talamus and the hypothalamic furrow separated from it is properly subbugs. The tires of the brain legs continue here, the red kernels and the black matter of the midbrain are completed here.
III ventricle.The cavity of the intermediate brain - III stomach It is a narrow sliding space located in the sagittal plane, limited from the sages of the medial surfaces of the thalamus, from the bottom of the hypothalamus, in front of the columns of the arch, the front spike and the terminal plate, behind the epithalamic (rear) spike, from above - the vault, over which the corpus body is located. Actually the top wall is formed by the vascular base of the III of the ventricle, in which its vascular plexus occurs.
The cavity III ventricle Zada \u200b\u200bgoes into a plumbing of the mid brain, and in front of the sides through the interventricular holes is reported to the side ventricles.
Medium brain
Medium brain - The smallest part of the brain, lying between the intermediate brain and the bridge (Fig.8.14 and 8.15). The area over the water pipe is called the roof of the mid-brain, and it contains four convexities - a plate of quadruses with upper and lower hills. From here there are ways of visual and auditory reflexes, heading in the spinal cord.
The legs of the brain are white rounded strands leaving the bridge and heading forward to the hemispheres of a large brain. From the furrow on the medial surface of each leg comes out the glazation nerve (III pair of cranial nerves). Each leg consists of a tire and base, the boundary between them is black substance. The color depends on the abundance of melanin in its nerve cells. The black substance refers to an extrapyramidal system, which is involved in maintaining muscle tone and automatically adjusts the operation of the muscles. The base of the leg is formed by nerve fibers, walking from the cortex of a large brain in the spinal and oblongable brain and bridge. The tire of the brain legs mainly ascending fibers heading to the Talamus, among which the kernels are locked. The largest are the red nuclei, from which the motor red-core motorway begins. In addition, a reticular formation and a core of the dorsal longitudinal beam (intermediate kernel) are located in the tire.
Rear brain
The bridge is located on the back of the brain, located ventral, and the cerebellum bridge behind the bridge.
Fig. 8.14. Schematic representation of a longitudinal brain cutting
Fig. 8.15. Cross cut through the middle brain at the level of the upper hills (the slice plane is shown in Fig. 8.14)
Bridge It looks like a lying cross-thickened roller, from the lateral side of which the middle cerebelling legs are departed on the left. The rear surface of the bridge, covered by a cerebellum, is involved in the formation of a diamondy hole, the front (adjacent to the base of the skull) borders with an oblong brain at the bottom and legs of the brain at the top (see Fig. 8.15). It is transversely exhausted due to the transverse direction of the fibers, which come from their own bridge cores into the middle cerebellary legs. On the front surface of the midline bridge, a Basilar groove is located longitudinally, in which the artery of the same name is held.
The bridge consists of a plurality of nerve fibers that form conductive paths, among which there are cellular clusters - kernels. The leading front tracks bind the bark of the big brain with the spinal cord and with the cerebulic hemispheal bark. In the back of the bridge (tires), rising conducting pathways and partially descending, is the reticular formation, the kernel V, VI, VII, VIII cranial nerve pairs. On the border between the two parts of the bridge, there is a trapezoidal body formed by nuclei and transversely walking fibers of the conducting path of the auditory analyzer.
Cerebellum Plays a major role in maintaining the equilibrium of the body and coordination of movements. The greatest development of the cerebellum reaches a person in connection with the smoothness and adaptation of the hand to work. In this regard, a person is strongly developed by a hemisphere (new part) of the cerebellum.
In the cerebellum there are two hemispheres and the unpaired median phylogenetically old part is a worm (Fig. 8.16).
Fig. 8.16. Cerebellum: top view and bottom
The surfaces of the hemispheres and the worm are separated by transverse parallel grooves, between which the narrow long sheets of cerebellum are located. In the cerebellum distinguish the front, rear and knocker-nodular shares separated by deeper sludge.
The cerebellum consists of gray and white substance. White substance, penetrating between gray, as if branching, forming on the median cut figure of a branching tree - "Tree of life" of the cerebellum.
The cerebral cortex consists of a gray substance with a thickness of 1-2.5 mm. In addition, in the thickness of the white substance there are clusters of gray - paired kernels: gear core, plug, spherical and core of the tent. Afferent and efferent fibers, binding cerebellum with other departments, form three pairs of ceremony legs: the lower heads are sent to the oblong brain, the average - to the bridge, the upper one - to quadruple.
By the time the cerebellum is less developed compared with the final brain (especially a hemisphere), but in the first year of life it develops faster than other brain departments. A pronounced magnification of the cerebellum is celebrated between the 5th and 11th months of life, when a child learns to sit and walk.
Medulla It is the immediate continuation of the spinal cord. His lower boundary is considered the place of the reserves of the first neck spinal nerve or the crossing of the pyramid, the top - the rear edge of the bridge, the length of it is about 25 mm, the form is approaching a truncated cone, the base upwards.
The front surface is separated by the anterior median slit, on the sides of which the pyramids formed by the pyramid-conductive paths are located, partially intersective (crossing the pyramids) in the depth of the described slot on the border with the spinal cord. The fibers of the pyramidal paths connect the bark of a large brain with the core nerve cores and the front horns of the spinal cord. On the side of the pyramid on each side there is an olive separated from the pyramid of the front lateral furrow.
The rear surface of the oblong brain is divided by the rear median furrows, on the sides of it are located to continue the rear cords of the spinal cord, which will diverge, turning into the lower cerebellar legs.
The oblong brain is built of white and gray matter, the latter is represented by the kernels of the IX-XII pairs of cranial nerves, olive, respiratory centers and blood circulation, reticular formation. White substance is formed by long and short fibers that make up the corresponding conductive paths.
Reticular formation It is a combination of cells, cell clusters and nerve fibers located in the brain barrel (oblong brain, bridge and middle brain) and forming the network. The reticular formation is associated with all the senses, motor and sensitive areas of the large brain cortex, the Talamus and the hypothalamus, spinal cord. It regulates the level of excitability and tone of various CNS departments, including a large brain bark, participates in regulation of the level of consciousness, emotions, sleep and wakefulness, vegetative functions, targeted movements.
IV ventricle - This is the cavity of the rhombid brain, the book he continues to the central spinal cord channel. The bottom of the IV ventricle due to its form is called a diamond straw (Fig. 8.17). It is formed by the rear surfaces of the oblong brain and the bridge, the upper sides of the pits are the top, and the bottom - the lower cerebellar legs.
Fig. 8.17. Brain stem; back view. The cerebellum is removed, the rhombid fossa is open
The middle groove divides the bottom of the pits into two symmetrical half, on both sides of the furrowes are visible by the medial elevations expanding in the middle of the holes in the right and left facial tubercles, where they lie: the core VI pair of cranial nerves (taking nerve), deeper and laterally - core VII pair ( Facial nerve), and the Book of Medial Elevation goes into the triangle of the sub-speaking nerve, the lateral nerve is a triangle of a wandering nerve. In triangles, in the thicker of the brain substance, the nuclei of the same names of the nerves. The top corner of the rhombid fossa is reported to the medium brain water supply. The side departments of the rhombid fossa were called vestibular fields, where hearing and vestibular nuclei of the proposable-snellest nerve (VIII pair of cranial nerves) are lying. From the auditory nuclei, the transverse brain strips are departed from the middle grooves, located on the border between the oblong brain and the bridge and which are the fibers of the conductive path of the auditory analyzer. In the thickness of the diamond pits, the kernels V, VI, VII, VIII, IX, X, XI and XII pairs of cranial nerves are locked.
Blood supply of the brain
Blood in the brain comes along two paired arteries: internal carotid and vertebral. In the cavity of the skull, both vertebral artery merge, together forming the main (basal) artery. On the basis of the brain, the main artery is merged with two carotid arteries, forming a single arterial ring (Fig. 8.18). Such a cascade mechanism of blood supply to the brain guarantees sufficient bloodstream, if any of the arteries fail.
Fig. 8.19. Arteries on the basis of the brain and vilisias circle (the right hemisphere of the cerebeller and the right temporal share are removed); Vilisians circle shown by dotted line
Three vessels are departed from the arterial ring: front, rear and middle brain artery, feeding the hemispheres of the brain. These arteries are on the surface of the brain, and from them deep into the brain, the blood is delivered by smaller arteries.
Sleepy arteries are called a carotid pool, which provides 2/3 of the brain needs in arterial blood and blood supply to the front and middle brain departments.
The arterial system "vertebrate is the main" is called the vertebobasilar pool, which provides 1/3 of the brain needs and delivers blood to the rear departments.
The outflow of venous blood occurs mainly through surface and deep brain veins and venous sinuses (Fig. 8.19). Ultimately, blood is directed to the inner jugular vein, which comes out of the skull through the jugular hole, located on the base of the skull side from the large occipital opening.
Brain shell
The shells of the brain protect it from mechanical damage and on the penetration of infections and toxic substances (Fig. 8.20).
Fig. 8.19. Vienna and venous brain sinuses
Fig.8.20. Coronary cut through skull shell and brain
The first shell protecting the brain is called the "soft brain shell". It is closely adjacent to the brain, it comes into all the furrows and cavities (ventricles), which are in the thicker of the brain itself. The ventricle of the brain is filled with liquid, which is called liquor or spinal (cerebrospinal) liquid. The solid brain shell is directly adjacent to the bones of the skull. Between the soft and solid shell is a web (arachnoidal) shell. There is space between the web and soft shells (subpautented or subarachnoid space) filled with liquor. Over the furrows of the brain, the cute shell eats up, forming a bridge, and soft merges with them. Due to this, cavities called tanks are formed between two shells. In the tanks there is a cerebrospinal fluid. These tanks protect the brain from mechanical injury by performing the role of "airbags".
Nervous cells and vessels are surrounded by neurogly - with special cellular formations that perform protective, support and metabolic function, providing the reactive properties of nervous tissue and participating in the formation of scars, in inflammation reactions, etc.
In case of damage to the brain, the mechanism of plasticity is included when the preserved structures of the brain take on the functions of the affected areas.
Localization of functions in a large brain core
General characteristics.In certain areas of the large brain cortex, predominantly neurons are concentrated, perceiving one kind of stimulus: the occipital region is light, the temporal share is the sound, etc. However, after the removal of classical projection zones (hearing, visual), conditional reflexes are partially saved to the corresponding stimuli. According to the theory of I. P. Pavlov in a large brain core, there is a "core" of the analyzer (cortical end) and "scattered" neurons throughout the crust. The modern concept of localization of functions is based on the principle of multifunctionality (but not equivalence) of the cortical fields. The property of multifunctionality allows one or another cortical structure to be included in the provision of various forms of activity, implementing the main one, genetically inherent in it, the function (O.S. Adrianov). The degree of multifunctionality of various cortical structures of non-etinakov. In the fields of associative crust, it is higher. At the heart of multifunctionality, the multichannel of admission to the bark of the brain of afferent excitation, overlapping of afferent excitations, especially on the thalamic and cortical levels, which modulates the influence of various structures, for example, nonspecific thalamus nuclei, basal ganglia on cortical functions, the interaction of cortical-subcortical and intercussion tract of excitation. Using microelectrode technology, it was possible to register in various fields of large brain cortex activity of specific neurons that respond to incentives only one type of stimulus (only on light, only on sound, etc.), i.e. there is a multiple representation of functions in a large brain core .
Currently, a division of the bark on sensory, motor and associative (non-specific) zones (regions) is taken.
Sensory bark zones.Sensory information enters the projection boron, the cortical departments of analyzers (I.P. Pavlov). These zones are located mainly in dark, temporal and occipital shares. The rising paths in the touch bark come mainly from the relay sensory nuclei of the Talamus.
Primary sensory zones - These are the zones of the sensory cortex, irritation or destruction of which causes clear and constant changes in the sensitivity of the body (the kernel of analyzers according to I. P. Pavlov). They consist of monomodal neurons and form sensations of one quality. In primary sensory zones, there is usually a clear spatial (topographic) representation of parts of the body, their receptor fields.
The primary projection zones of the cortex consist mainly from the neurons of the 4th afferent layer for which a clear topical organization is characteristic. A significant part of these neurons has the highest specificity. For example, neurons of visual regions selectively react to certain signs of visual stimuli: Some - on the shades of color, others - to the direction of movement, the third - on the character of the lines (edge, strip, slope of the line), etc. However, it should be noted that the multimodal type neurons react to several types of irritants are also included in the primary zones of individual crust areas. In addition, there are neurons there, the reaction of which reflects the impact of non-specific (limbico-reticular, or modulating) systems.
Secondary sensory zones located around primary sensory zones, less localized, their neurons respond to several stimuli, i.e. They are polymodal.
Localization of sensory zones. The most important sensory area is dark Sharepost-central winding and the corresponding part of the paraccentral lobby on the medial surface of the hemispheres. This zone is indicated as somatosensory regionI.. Here there is a projection of the skin sensitivity of the opposite side of the body from tactile, pain, temperature receptors, interoceptive sensitivity and sensitivity of the musculoskeletal system - from muscle, articular, tendon receptors (Fig. 2).
Fig. 2. Scheme of sensitive and motor homunculus
(U. Penfield, T. Rasmussen). Enclosure section in the frontal plane:
but- the projection of the general sensitivity in the core of post-central ispud; b.- Projection of the motor system in the core of precentral winding
In addition to the somatosensory region I allocate somatosensory regionII smaller sizes located on the border of the intersection of the central furridge with the upper edge temporal sharein the depths of the lateral furrow. The accuracy of the localization of body parts here is expressed to a lesser extent. Well-studied primary projection zone is hearing bark(Fields 41, 42), which is located in the depths of the lateral groove (cross-headed hemiscores Geshal). The projection core of the temporal share also includes the center of the vestibular analyzer in the upper and medium temporal convictions.
IN baselinesituated primary visual area(Bark parts of wedge-shaped gyrus and tongue slices, field 17). There is a topical representation of retina receptors. Each point of the retina corresponds to its section of the visual bark, while the zone of the yellow spot has a relatively large zone of the representation. Due to the incomplete crossroads of the visual tract in the visual region of each hemisphere, the same ages of the retina are projected. The presence in each hemisphere of the retinal projection of both eyes is the basis of binocular vision. Near the field 17 is the bark secondary visual region(fields 18 and 19). Neurons of these zones are polymodal and respond not only to light, but also tactile and auditory stimuli. In this visual region, the synthesis of various types of sensitivity occurs, there are more complex visual images and their identification.
In secondary zones, the 2nd and 3rd layers of neurons are the main part of the environmental information and the inner environment of the body, which entered the sensory bore, is transmitted to its further processing into an associative boron, after which it is initiated (if necessary) Behavioral reaction with the obligatory participation of the motor cortex.
Motor cortexes.Select primary and secondary motor zones.
IN primary motor zone (Presencentral Cross, Field 4) There are neurons, innervating motionones of the muscles of the face, torso and limbs. It has a clear topographic projection of the muscles of the body (see Fig. 2). The main pattern of the topographic representation is that the regulation of muscle activity providing the most accurate and varied movements (speech, letter, facial expressions) requires the participation of large in the area of \u200b\u200bmotion cortex. An irritation of the primary motor cortex causes contraction of the muscles of the opposite side of the body (for the muscles of the head abbreviation can be bilateral). With the defeat of this cortical zone, the ability to be lost to thin coordinated movements by limbs, especially fingers.
Secondary motor zone (Field 6) is located both on the lateral surface of the hemispheres, ahead of the presencentral winding (premotor cortex) and on the medial surface corresponding to the cortex of the upper frontal winding (an additional engine area). The secondary motion cortex in the functional plan has a dominant value relative to the primary motorbate, carrying out the highest motor functions associated with the planning and coordination of arbitrary movements. Here is most recorded slowly increasing negative readiness potentialarising about 1 seconds before the start of movement. The bark of the field 6 receives the bulk of the impulse from the basal ganglia and the cerebellum, participates in the transcoding of information about the plan of complex movements.
Irritation of the field of field 6 causes complex coordinated movements, such as turning the head, eye and torso in the opposite side, friendly cuts of flexors or extensors on the opposite side. In Primorny Core, there are motor centers associated with the social functions of a person: a written speech center in the backyard of the middle frontal winding (field 6), the center of the Motor speech of the Brock in the rear section of the lower frontal winding (field 44), providing speech praxis, as well as musical motor Center (field 45), providing speech tone, Singing ability. Motor cortex neurons receive afferent entrances through the thalamus from muscle, articular and skin receptors, from basal ganglia and cerebellum. The main efferent output of the motor cortex on stem and spinal engine centers are pyramid cells V layer. The main shares of the Big Brain bark are presented in Fig. 3.
Fig. 3. Four main shares of the cerebral cortex (frontal, temporal, dark and occipital); side view. They are located primary motor and sensory domain, motor and sensory areas of higher order (second, third, etc.) and associative (nonspecific) bark
Associative areas of the crust(nonspecific, intersensive, inter-cortex cortex) include the sections of the new large brain cortex, which are located around the projection zones and next to the motor zones, but do not perform directly sensitive or motor functions, so they can not be attributed to predominantly sensory or motor functions, these zone neurons have large Learning abilities. The boundaries of these regions are not indicated well. The associative bark is the phylogenetically the most young part of the new bark, which has gained the greatest development of primates and in humans. It has about 50% of the entire bark or 70% of neocortex. The term "associative bark" arose due to the existing idea that these zones due to the cortic-cortical compounds passing through them connect the motor zones and simultaneously serve as a substrate of higher mental functions. Basic associative cortex zonesare: dark-temporal-occipital, prefrontal bark of frontal fractions and a limbic associative zone.
The neurons of the associative bark are polyessence (polymodal): they are responsible, as a rule, not one (as neurons of primary sensory zones), but by several stimuli, i.e. the same neuron can be excited when irritating the hearing, visual, skin and Dr. receptors. The polyessence of the neurons of the associative bark is created by cortico-cortical connections with different projection zones, associative bonds of the Talamus. As a result, the associative bark is a kind of collector of various sensory excitations and participates in the integration of sensory information and in ensuring the interaction of sensory and motor areas of the crust.
Associative areas occupy the 2nd and 3rd cellular layers of the associative bark, on which there is a meeting of powerful single-scale, different-scale and non-specific afferent flows. The work of these brain bark departments are necessary not only for successful synthesis and differentiation (selective distinctions) of the person perceived by a person, but also for transition to the level of their symbolization, that is, for operating the words and use the words and use them for distracted thinking, for the synthetic nature of perception.
Since 1949, D. Hebba hypothesis was widely fame, which postulates the coincidence of the presynaptic activity with the discharge of post-synptic neuron as the condition of the synaptic modification, since not any activity of synapse leads to the excitation of postsynaptic neuron. Based on D. Hebb's hypothesis, it can be assumed that the individual neurons of the associative cortex zones are connected with a variety of ways and form cell ensembles that allocate "appeals", i.e. corresponding to unitary forms of perception. These links, as noted by D.Hebb, are so well developed that it is enough to activate one neuron, as the entire ensemble is excited.
The device performing the role of the wake level regulator, as well as using selective modulation and updating the priority of a particular function, is a modulating brain system, which is often referred to as a limbic-reticulous complex, or an upward activating system. The nerve formations of this apparatus include limbic and nonspecific brain systems with activating and inactivating structures. Among the activating formations, first of all, the reticular formation of the mid-brain, the rear hypothalamus, the blue spot in the lower sections of the brain stem. Inactivating structures include the precortic region of the hypothalamus, the seam kernel in the brain barrel, frontal bark.
Currently, on tamlamocortical projections, it is proposed to allocate three main associative brain systems: talamum, Talamolobnya and talamumochnyh.
Talamum system represented by associative areas of the parietal bark that receive the main afferent entrances from the rear group of associative nuclei of the Talamus. The Dark Associative Cora has efferent yields on the thalamus kernels and the hypothalamus, in the engine bore and the core of the extrapyramidal system. The main functions of the talamum system are Gnosis and Praxis. Under gnocompon understand the function of various types of recognition: forms, values, values \u200b\u200bof objects, understanding of speech, knowledge of processes, patterns, etc. The estimation of spatial relations is related to the gnostic functions, for example, the mutual location of the items. In the parietal cortex, the center of stereogenis is allocated, which ensures the ability to recognize items to the touch. A variant of the gnostic function is the formation of a three-dimensional body model in the consciousness ("body scheme"). Under praxis understand targeted action. Praxis's center is located in the suprakkaya urinet of the left hemisphere, it provides storage and implementation of the program of motor automated acts.
Talalamolobic system represented by associative zones of a frontal bark having a basic afferent entrance from the associative medium-appliance core of Talamus, other subcortical nuclei. The main role of the frontal associative bark is reduced to the initiation of basic systemic mechanisms for the formation of functional systems of targeted behavioral acts (P. K.Anokhin). The prefortional area plays a major role in developing a behavior strategy.Violation of this function is especially noticeable when it is necessary to quickly change the action and when there is some time between the task and the beginning of its decision, i.e. I have time to accumulate stimuli, requiring the right inclusion in a holistic behavioral reaction.
Talamumian system. Some associative centers, for example, stereoognosis, Praxis, include the sections of the temporal bark. In the temporal crust there is a hearing center of speech Wernik, located in the rear departments of the upper temporal winding of the left hemisphere. This center provides speech gnosis: recognition and storage of oral speech as their own and someone else's. In the middle of the upper temporal winding, there is a center for recognizing musical sounds and their combinations. On the border of the temporal, rare and occipital fraction is the reading center, providing recognition and storage of images.
A significant role in the formation of behavioral acts is played by the biological quality of unconditional reaction, namely, its importance for saving life. In the process of evolution, this value was enshrined in two opposite emotional states - positive and negative, which in humans form the basis of its subjective experiences - pleasure and displeasure, joy and sorrow. In all cases, targeted behavior is built in accordance with the emotional state that has arisen under the action of an irritant. During behavioral reactions of a negative nature, the voltage of vegetative components, especially the cardiovascular system, in some cases, especially in continuous so-called conflict situations, can achieve a great force that causes a violation of their regulatory mechanisms (vegetative neurosis).
In this part of the book, the main general issues of analytical synthetic activity of the brain, which will allow for the following chapters to present private issues of physiology of sensory systems and higher nervous activity.
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