How does the cerebral cortex work? Areas of the cerebral cortex. The structure and functions of the cerebral cortex

At present, it is known for certain that the higher functions nervous system, such as the ability to comprehend signals received from the external environment, to mental activity, to remember and think, are largely determined by how the cerebral cortex functions. We will consider the zones of the cerebral cortex in this article.

The fact that a person is aware of his relationships with other people is associated with the excitation of neural networks. We are talking about those that are located precisely in the cortex. It is the structural basis of intellect and consciousness.

neocortex

There are about 14 billion neurons in the cerebral cortex. The areas of the cerebral cortex, which will be discussed below, function thanks to them. The main part of neurons (about 90%) forms the neocortex. It belongs to the somatic nervous system, being its highest integrative department. The most important function of the neocortex is the processing and interpretation of information received with the help of the sense organs (visual, somatosensory, gustatory, auditory). It is also important that it is he who controls complex muscle movements. In the neocortex there are centers that take part in the processes of speech, abstract thinking, as well as memory storage. The main part of the processes occurring in it is the neurophysiological basis of our consciousness.

paleocortex

The paleocortex is another large and important department, which has a cerebral cortex. The areas of the cerebral cortex related to it are also very important. This part has a simpler structure than the neocortex. The processes taking place here are not always reflected in consciousness. The paleocortex contains the highest vegetative centers.

Communication of the cortex with the underlying parts of the brain

It should be noted that the connection of the cortex with the underlying parts of our brain (thalamus, bridge and It is carried out with the help of large bundles of fibers that form the inner capsule. These bundles of fibers are wide layers composed of white matter. They contain many nerve fibers (millions). Some of these fibers (axons of thalamic neurons) provide transmission of nerve signals to the cortex.The other part, namely the axons of cortical neurons, serves to transmit them to the nerve centers located below.

The structure of the cerebral cortex

Do you know which part of the brain is the largest? Some of you have probably guessed what I'm talking about. This is the cerebral cortex. Areas of the cerebral cortex are just one type of parts that stand out in it. So, it is divided into right and left hemisphere. They are connected to each other by bundles of white matter, which forms the main function of the corpus callosum is to ensure the coordination of the activities of the two hemispheres.

Areas of the cerebral cortex by location

Although there are many folds in the cerebral cortex, in general, the location of the most important furrows and convolutions is characterized by constancy. Therefore, the main ones serve as a guideline in the division of cortical regions. Its outer surface is divided into 4 lobes by three furrows. These lobes (zones) are temporal, occipital, parietal and frontal. Although they stand out by location, each of them has its own specific functions.

The temporal zone of the cerebral cortex is the center where the cortical layer of the auditory analyzer is located. In case of damage, deafness occurs. The auditory area of ​​the cerebral cortex, in addition, has a Wernicke speech center. If it is damaged, the ability to understand oral speech is lost. It starts to feel like noise. In addition, there are neuronal centers related to the vestibular apparatus. The sense of balance is disturbed if they are damaged.

The speech areas of the cerebral cortex are concentrated in the frontal lobe. This is where the speech center is located. If it is damaged, the ability to change the intonation and timbre of speech will be lost. She becomes monotonous. If the damage relates to the left hemisphere, where there are also speech zones of the cerebral cortex, articulation disappears. The ability to sing and articulate speech also disappears.

The visual cortex corresponds to the occipital lobe. Here is the department that is responsible for our vision as such. We perceive the world around us with the brain, not with the eyes. Responsible for vision occipital part. Therefore, in case of its damage, complete or partial blindness develops.

The parietal lobe also has its own specific functions. She is responsible for the analysis of information relating to general sensitivity: tactile, temperature, pain. If it is damaged, the ability to recognize objects by touch, as well as some other abilities, is lost.

Motor zone

I would like to talk about it separately. The fact is that the motor area of ​​the cerebral cortex does not correlate with the shares that we talked about above. It is a part of the cortex that contains direct descending connections with the spinal cord, more precisely, with its motor neurons. This is the name of the neurons that directly control the work of the muscles.

The main motor area of ​​the cerebral cortex is located in In many ways, this gyrus is a mirror image of another area, the sensory one. There is contralateral innervation. In other words, innervation occurs in relation to the muscles located on the opposite side of the body. The exception is the facial region, which has bilateral control of the muscles of the jaw and lower face.

Another additional motor area of ​​the cerebral cortex is located in the area below the main area. Scientists believe that it has independent functions associated with the output of motor impulses. This motor cortex has also been studied by scientists. In experiments on animals, it was found that its stimulation leads to the emergence of motor reactions. Moreover, this happens even if the main motor area of ​​the cerebral cortex was previously destroyed. In the dominant hemisphere, it is involved in the motivation of speech and in the planning of movements. Scientists believe that its damage leads to dynamic aphasia.

Areas of the cerebral cortex by function and structure

As a result of clinical observations and physiological experiments carried out in the second half of the 19th century, the boundaries of the areas into which various receptor surfaces are projected were established. Among the latter, both those aimed at the outside world (skin sensitivity, hearing, vision) and those that are embedded in the organs of movement themselves (kinetic, or motor analyzer) are singled out.

The occipital region is the zone of the visual analyzer (fields 17 to 19), the upper temporal region is the auditory analyzer (fields 22, 41 and 42), the post-central region is the skin-kinesthetic analyzer (fields 1, 2 and 3).

Cortical representatives of various analyzers according to their functions and structure are divided into the following 3 zones of the cerebral cortex: primary, secondary and tertiary. On the early period, during the development of the embryo, it is precisely the primary ones that are characterized by simple cytoarchitectonics. The tertiary ones develop last. They have the most complex structure. An intermediate position from this point of view is occupied by the secondary zones of the hemispheres of the cerebral cortex. We invite you to take a closer look at the functions and structure of each of them, as well as their relationship with the brain regions located below, in particular, with the thalamus.

Center fields

Scientists over the years of study have accumulated significant experience in clinical research. As a result of observations, it was found, in particular, that damage to certain fields in the composition of the cortical representatives of the analyzers affect the overall clinical picture is far from being equivalent. Among the other fields, one stands out in this respect, which occupies a central position in the nuclear zone. It is called primary or central. They are field number 17 in the visual zone, in the auditory - at number 41, and in the kinesthetic - 3. Their damage leads to very serious consequences. The ability to perceive or carry out the most subtle differentiations of stimuli of the corresponding analyzers is lost.

Primary Zones

In the primary zone, the complex of neurons is most developed, which is adapted to provide cortical-subcortical bilateral connections. It connects the cortex with one or another sense organ in the shortest and most direct way. Because of this, the primary zones of the cerebral cortex can highlight stimuli in sufficient detail.

Important common feature functional and structural organization of these areas is that they all have a clear somatotopic projection. This means that separate points of the periphery (the retina of the eye, the skin surface, the cochlea of ​​the inner ear, skeletal muscles) are projected into the corresponding, strictly delimited points located in the primary zone of the cortex of the corresponding analyzer. For this reason, they began to be called projection.

Secondary zones

Otherwise they are called peripheral, and this is not accidental. They are located in the nuclear areas of the cortex, in their peripheral sections. The secondary zones differ from the primary, or central ones, in terms of physiological manifestations, neuronal organization, and architectonic features.

What effects are observed when they are electrically stimulated or damaged? These effects concern mainly more complex species. mental processes. If the secondary zones are affected, then elementary sensations are relatively preserved. Basically, the ability to correctly reflect the mutual relationships and whole complexes of the constituent elements of various objects that we perceive is upset. If the secondary zones of the auditory and visual cortex are irritated, then auditory and visual hallucinations are observed, deployed in a certain sequence (temporal and spatial).

These areas are very important for the implementation of the mutual connection of stimuli, the selection of which occurs with the help of primary zones. In addition, they play a significant role in the integration of the functions of nuclear fields of various analyzers when combining receptions into complex complexes.

Secondary zones, therefore, are important for the implementation of more complex forms of mental processes that require coordination and are associated with a thorough analysis of the ratios of objective stimuli, as well as orientation in time and in the surrounding space. In this case, links are established, called associative ones. Afferent impulses, which are sent from the receptors of various superficial sense organs to the cortex, reach these fields through many additional switchings in the associative nuclei of the thalamus (thalamic thalamus). In contrast, afferent impulses that follow the primary zones reach them in a shorter way through the relay-nucleus of the thalamus.

What is the thalamus

Fibers from the thalamic nuclei (one or more) come to each lobe of the hemispheres of our brain. The visual tubercle, or thalamus, is located in the forebrain, in its central region. It consists of many nuclei, while each of them transmits an impulse to a strictly defined area of ​​\u200b\u200bthe cortex.

All signals coming to it (except for olfactory ones) pass through the relay and integrative nuclei of the thalamus. Further, the fibers go from them to the sensory zones (in the parietal lobe - to the taste and somatosensory, in the temporal - to the auditory, in the occipital - to the visual). Pulses come from the ventrobasal complex, medial and lateral nuclei, respectively. As for the motor areas of the cortex, they have a connection with the ventrolateral and anterior ventral nuclei of the thalamus.

EEG desynchronization

What happens if a person who is at rest is suddenly presented with some strong stimulus? Of course, he will immediately become alert and concentrate his attention on this irritant. The transition of mental activity, carried out from rest to a state of activity, corresponds to the replacement of the EEG alpha rhythm with a beta rhythm, as well as other more frequent fluctuations. This transition, called EEG desynchronization, appears as a result of the fact that sensory excitations enter the cortex from nonspecific nuclei of the thalamus.

activating reticular system

Nonspecific nuclei make up a diffuse nervous network located in the thalamus, in its medial sections. This is the anterior section of the ARS (activating reticular system), which regulates the excitability of the cortex. Various sensory signals can activate APC. They can be visual, vestibular, somatosensory, olfactory and auditory. APC is a channel through which these signals are transmitted to the surface layers of the cortex through non-specific nuclei located in the thalamus. The excitation of ARS plays an important role. It is necessary to keep you awake. In experimental animals in which this system was destroyed, a coma-like sleep-like state was observed.

Tertiary zones

The functional relationships that are traced between parsers are even more complex than described above. Morphologically, their further complication is expressed in the fact that in the process of growth over the surface of the hemisphere of the nuclear fields of the analyzers, these zones mutually overlap. At the cortical ends of the analyzers, "overlap zones" are formed, that is, tertiary zones. These formations are among the most complex types of combining the activities of skin-kinesthetic, auditory and visual analyzers. The tertiary zones are already located outside the boundaries of their own nuclear fields. Therefore, their irritation and damage does not lead to pronounced phenomena of loss. Also, no significant effects are observed with respect to the specific functions of the analyzer.

Tertiary zones are special areas of the cortex. They can be called a collection of "scattered" elements of various analyzers. That is, these are elements that by themselves are no longer capable of producing any complex syntheses or analyzes of stimuli. The territory they occupy is quite extensive. It breaks down into a number of areas. Let's briefly describe them.

The superior parietal region is important for integrating whole body movements with visual analyzers, as well as for the formation of the body scheme. As for the lower parietal, it refers to the unification of abstract and generalized forms of signaling associated with complex and finely differentiated speech and object actions, the implementation of which is controlled by vision.

The temporo-parieto-occipital region is also very important. She is responsible for complex types of integration of visual and auditory analyzers with written and oral speech.

Note that tertiary zones have the most complex communication chains compared to primary and secondary ones. Bilateral connections are observed in them with a complex of thalamic nuclei, connected, in turn, with relay nuclei through a long chain of internal connections that are directly in the thalamus.

Based on the foregoing, it is clear that in humans the primary, secondary, and tertiary zones are areas of the cortex that are highly specialized. It should be especially emphasized that the 3 groups of cortical zones described above, in a normally functioning brain, together with the systems of connections and switching between themselves, as well as with subcortical formations, function as one complexly differentiated whole.

glial cells; it is located in some parts of the deep brain structures, the cortex of the cerebral hemispheres (as well as the cerebellum) is formed from this substance.

Each hemisphere is divided into five lobes, four of which (frontal, parietal, occipital and temporal) are adjacent to the corresponding bones of the cranial vault, and one (insular) is located in depth, in the fossa that separates the frontal and temporal lobes.

The cerebral cortex has a thickness of 1.5–4.5 mm, its area increases due to the presence of furrows; it is connected with other parts of the central nervous system, thanks to the impulses that neurons conduct.

The hemispheres make up approximately 80% of the total mass of the brain. They carry out the regulation of higher mental functions, while the brain stem is lower, which are associated with the activity of internal organs.

Three main regions are distinguished on the hemispheric surface:

• convex upper lateral, which is adjacent to the inner surface of the cranial vault;
• lower, with the anterior and middle sections located on the inner surface of the cranial base and the posterior ones in the region of the cerebellum;
• the medial is located at the longitudinal fissure of the brain.

Features of the device and activities

The cerebral cortex is divided into 4 types:

• ancient - occupies a little more than 0.5% of the entire surface of the hemispheres;
• old - 2.2%;
• new - more than 95%;
• the average is about 1.5%.

The phylogenetically ancient cerebral cortex, represented by groups of large neurons, is pushed aside by the new one to the base of the hemispheres, becoming a narrow strip. And the old one, consisting of three cell layers, shifts closer to the middle. The main region of the old cortex is the hippocampus, which is central department limbic system. The middle (intermediate) crust is a formation of a transitional type, since the transformation of old structures into new ones is carried out gradually.

The human cerebral cortex, unlike that of mammals, is also responsible for the coordinated work of internal organs. Such a phenomenon, in which the role of the cortex in the implementation of all the functional activities of the body increases, is called the corticalization of functions.

One of the features of the cortex is its electrical activity, which occurs spontaneously. Nerve cells located in this section have a certain rhythmic activity, reflecting biochemical, biophysical processes. Activity has a different amplitude and frequency (alpha, beta, delta, theta rhythms), which depends on the influence of numerous factors (meditation, sleep phases, stress, the presence of convulsions, neoplasms).

Structure

The cerebral cortex is a multilayer formation: each of the layers has its own specific composition of neurocytes, a specific orientation, and the location of processes.

The systematic position of neurons in the cortex is called "cytoarchitectonics", the fibers arranged in a certain order are called "myeloarchitectonics".

The cerebral cortex consists of six cytoarchitectonic layers.

1. Surface molecular, in which there are not very many nerve cells. Their processes are located in himself, and they do not go beyond.
2. The outer granular is formed from pyramidal and stellate neurocytes. The processes leave this layer and go to the next ones.
3. Pyramidal consists of pyramidal cells. Their axons go down where they end or form association fibers, and their dendrites go up to the second layer.
4. The internal granular is formed by stellate cells and small pyramidal. The dendrites go into the first layer, the lateral processes branch out within their own layer. Axons extend into the upper layers or into the white matter.
5. Ganglionic is formed by large pyramidal cells. Here are the largest neurocytes of the cortex. The dendrites are directed to the first layer or distributed in their own. Axons leave the cortex and begin to be fibers that connect various departments and structures of the central nervous system with each other.
6. Multiform - consists of various cells. Dendrites go to the molecular layer (some only up to the fourth or fifth layers). Axons are sent to the overlying layers or exit the cortex as association fibers.

The cerebral cortex is divided into regions - the so-called horizontal organization. There are 11 of them in total, and they include 52 fields, each of which has its own serial number.

Vertical organization

There is also a vertical division - into columns of neurons. In this case, small columns are combined into macro columns, which are called a functional module. At the heart of such systems are stellate cells - their axons, as well as their horizontal connections with the lateral axons of pyramidal neurocytes. All nerve cells in the vertical columns respond to the afferent impulse in the same way and together send an efferent signal. Excitation in the horizontal direction is due to the activity of transverse fibers that follow from one column to another.

He first discovered units that unite neurons of different layers vertically in 1943. Lorente de No - with the help of histology. Subsequently, this was confirmed using methods of electrophysiology on animals by W. Mountcastle.

The development of the cortex in fetal development begins early: as early as 8 weeks, the embryo has a cortical plate. First, the lower layers differentiate, and at 6 months, the unborn child has all the fields that are present in an adult. The cytoarchitectonic features of the cortex are fully formed by the age of 7, but the bodies of neurocytes increase even up to 18. For the formation of the cortex, coordinated movement and division of precursor cells from which neurons emerge are necessary. It has been established that this process is influenced by a special gene.

Horizontal organization

It is customary to divide the areas of the cerebral cortex into:

• associative;
• sensory (sensitive);
• motor.

Scientists in the study of localized areas and their functional features various methods were used: chemical or physical irritation, partial removal of brain areas, development of conditioned reflexes, registration of brain biocurrents.

sensitive

These areas occupy approximately 20% of the cortex. The defeat of such zones leads to a violation of sensitivity (reduction of vision, hearing, smell, etc.). The area of ​​the zone directly depends on the number of nerve cells that perceive the impulse from certain receptors: the more there are, the higher the sensitivity. Allocate zones:

• somatosensory (responsible for skin, proprioceptive, autonomic sensitivity) - it is located in the parietal lobe (postcentral gyrus);
• visual, bilateral damage that leads to complete blindness, - located in the occipital lobe;
• auditory (located in the temporal lobe);
• taste, located in the parietal lobe (localization - postcentral gyrus);
• olfactory, bilateral violation of which leads to loss of smell (located in the hippocampal gyrus).

Violation of the auditory zone does not lead to deafness, but other symptoms appear. For example, the impossibility of distinguishing short sounds, the meaning of everyday noises (steps, pouring water, etc.) while maintaining the difference in pitch, duration, and timbre. Amusia can also occur, which consists in the inability to recognize, reproduce melodies, and also distinguish between them. Music can also be accompanied by unpleasant sensations.

Impulses going along afferent fibers from the left side of the body are perceived by the right hemisphere, and with right side- left (damage to the left hemisphere will cause a violation of sensitivity on the right side and vice versa). This is due to the fact that each postcentral gyrus is connected to the opposite part of the body.

Motor

The motor areas, the irritation of which causes the movement of the muscles, are located in the anterior central gyrus of the frontal lobe. Motor areas communicate with sensory areas.

The motor pathways in the medulla oblongata (and partially in the spinal cord) form a decussation with a transition to the opposite side. This leads to the fact that the irritation that occurs in the left hemisphere enters the right half of the body, and vice versa. Therefore, damage to the cortex of one of the hemispheres leads to a violation motor function muscles on the opposite side of the body.

The motor and sensory areas, which are located in the region of the central sulcus, are combined into one formation - the sensorimotor zone.

Neurology and neuropsychology have accumulated a lot of information about how the defeat of these areas leads not only to elementary movement disorders (paralysis, paresis, tremors), but also to disorders arbitrary movements and actions with objects - apraxia. When they appear, movements during writing may be disturbed, spatial representations may be disturbed, and uncontrolled patterned movements may appear.

Associative

These zones are responsible for linking the incoming sensory information with the one that was previously received and stored in memory. In addition, they allow you to compare information that comes from different receptors. The response to the signal is formed in the associative zone and transmitted to the motor zone. Thus, each associative area is responsible for the processes of memory, learning and thinking.. Large associative zones are located next to the corresponding functional sensory zones. For example, any associative visual function is controlled by the visual association area, which is located next to the sensory visual area.

Establishing the laws of the brain, analyzing its local disorders and checking its activity is carried out by the science of neuropsychology, which is located at the intersection of neurobiology, psychology, psychiatry and informatics.

Features of localization by fields

The cerebral cortex is plastic, which affects the transition of the functions of one department, if it is disturbed, to another. This is due to the fact that the analyzers in the cortex have a core, where the highest activity takes place, and a periphery, which is responsible for the processes of analysis and synthesis in a primitive form. Between the analyzer cores there are elements that belong to different analyzers. If the damage touches the nucleus, peripheral components begin to take responsibility for its activity.

Thus, the localization of functions possessed by the cerebral cortex is a relative concept, since there are no definite boundaries. However, cytoarchitectonics suggests the presence of 52 fields that communicate with each other through pathways:

• associative (this type of nerve fibers is responsible for the activity of the cortex in the region of one hemisphere);
• commissural (connect symmetrical areas of both hemispheres);
• projection (contribute to the communication of the cortex, subcortical structures with other organs).

Table 1

		Relevant fields
Motor
sensitive
visual
Olfactory
Taste
Speech motor, which includes centers:	Wernicke, which allows you to perceive oral speech
	Broca - responsible for the movement of the tongue muscles; defeat threatens with a complete loss of speech
	Perception of speech in writing

So, the structure of the cerebral cortex involves considering it in a horizontal and vertical orientation. Depending on this, vertical columns of neurons and zones located in the horizontal plane are distinguished. The main functions performed by the cortex are reduced to the implementation of behavior, regulation of thinking, consciousness. In addition, it ensures the interaction of the body with the external environment and takes part in the control of the work of internal organs.

Cortex - the highest department of the central nervous system, which ensures the functioning of the body as a whole in its interaction with the environment.

brain (cerebral cortex, neocortex) is a layer of gray matter, consisting of 10-20 billion and covering the large hemispheres (Fig. 1). The gray matter of the cortex makes up more than half of the total gray matter of the CNS. The total area of ​​the gray matter of the cortex is about 0.2 m 2, which is achieved by the sinuous folding of its surface and the presence of furrows of different depths. The thickness of the cortex in its different parts ranges from 1.3 to 4.5 mm (in the anterior central gyrus). The neurons of the cortex are arranged in six layers oriented parallel to its surface.

In the areas of the cortex related to, there are zones with a three-layer and five-layer arrangement of neurons in the structure of the gray matter. These areas of the phylogenetically ancient cortex occupy about 10% of the surface of the cerebral hemispheres, the remaining 90% are the new cortex.

Rice. 1. Mole of the lateral surface of the cerebral cortex (according to Brodman)

The structure of the cerebral cortex

The cerebral cortex has a six-layer structure

Neurons of different layers differ in cytological features and functional properties.

molecular layer- the most superficial. It is represented by a small number of neurons and numerous branching dendrites of pyramidal neurons lying in deeper layers.

Outer granular layer formed by densely spaced numerous small neurons of various shapes. The processes of the cells of this layer form corticocortical connections.

Outer pyramidal layer consists of pyramidal neurons of medium size, the processes of which are also involved in the formation of corticocortical connections between adjacent areas of the cortex.

Inner granular layer similar to the second layer in terms of cell type and fiber arrangement. In the layer there are bundles of fibers that connect various parts of the cortex.

Signals from specific nuclei of the thalamus are carried to the neurons of this layer. The layer is very well represented in the sensory areas of the cortex.

Inner pyramidal layers formed by medium and large pyramidal neurons. In the motor area of ​​the cortex, these neurons are especially large (50-100 microns) and are called giant, pyramidal Betz cells. The axons of these cells form fast-conducting (up to 120 m/s) fibers of the pyramidal tract.

Layer of polymorphic cells It is represented mainly by cells whose axons form corticothalamic pathways.

Neurons of the 2nd and 4th layers of the cortex are involved in the perception, processing of signals coming to them from the neurons of the associative areas of the cortex. Sensory signals from the switching nuclei of the thalamus come mainly to the neurons of the 4th layer, the severity of which is greatest in the primary sensory areas of the cortex. The neurons of the 1st and other layers of the cortex receive signals from other nuclei of the thalamus, the basal ganglia, and the brain stem. Neurons of the 3rd, 5th and 6th layers form efferent signals sent to other areas of the cortex and downstream to the underlying parts of the CNS. In particular, the neurons of the 6th layer form fibers that follow to the thalamus.

AT neural composition and cytological features of different parts of the cortex, there are significant differences. According to these differences, Brodman divided the cortex into 53 cytoarchitectonic fields (see Fig. 1).

The location of many of these fields, identified on the basis of histological data, coincides in topography with the location of the cortical centers, identified on the basis of their functions. Other approaches to dividing the cortex into regions are also used, for example, based on the content of certain markers in neurons, according to the nature of neuronal activity, and other criteria.

The white matter of the cerebral hemispheres is formed by nerve fibers. Allocate association fibers, subdivided into arcuate fibers, but to which signals are transmitted between neurons of adjacent gyri and long longitudinal bundles of fibers that deliver signals to neurons of more distant parts of the hemisphere of the same name.

Commissural fibers - transverse fibers that transmit signals between neurons of the left and right hemispheres.

Projection fibers - conduct signals between the neurons of the cortex and other parts of the brain.

The listed types of fibers are involved in the creation of neural circuits and networks, the neurons of which are located at considerable distances from each other. There is also a special kind of local neural circuits in the cortex, formed by adjacent neurons. These neural structures are called functional cortical columns. Neuronal columns are formed by groups of neurons located one above the other perpendicular to the surface of the cortex. The belonging of neurons to the same column can be determined by the increase in their electrical activity in response to stimulation of the same receptive field. Such activity is recorded when the recording electrode is slowly moved in the cortex in a perpendicular direction. If the electrical activity of neurons located in the horizontal plane of the cortex is recorded, then an increase in their activity is noted when various receptive fields are stimulated.

The diameter of the functional column is up to 1 mm. The neurons of one functional column receive signals from the same afferent thalamocortical fiber. The neurons of adjacent columns are connected to each other by processes through which they exchange information. The presence of such interconnected functional columns in the cortex increases the reliability of perception and analysis of information coming to the cortex.

The efficiency of perception, processing and use of information by the cortex for the regulation of physiological processes is also ensured somatotopic principle of organization sensory and motor fields of the cortex. The essence of such an organization is that in a certain (projective) area of ​​the cortex, not any, but topographically outlined areas of the receptive field of the surface of the body, muscles, joints, or internal organs are represented. So, for example, in the somatosensory cortex, the surface of the human body is projected in the form of a scheme, when receptive fields of a specific area of ​​the body surface are presented at a certain point in the cortex. Efferent neurons are represented in a strict topographical way in the primary motor cortex, the activation of which causes the contraction of certain muscles of the body.

The fields of the cortex are also inherent screen operating principle. In this case, the receptor neuron sends a signal not to a single neuron or to a single point of the cortical center, but to a network or field of neurons connected by processes. The functional cells of this field (screen) are columns of neurons.

The cerebral cortex, being formed at the later stages of the evolutionary development of higher organisms, to a certain extent subordinated to itself all the underlying parts of the CNS and is able to correct their functions. At the same time, the functional activity of the cerebral cortex is determined by the influx of signals to it from the neurons of the reticular formation of the brain stem and signals from the receptive fields of the sensory systems of the body.

Functional areas of the cerebral cortex

According to the functional basis, sensory, associative and motor areas are distinguished in the cortex.

Sensory (sensitive, projection) areas of the cortex

They consist of zones containing neurons, the activation of which by afferent impulses from sensory receptors or direct exposure to stimuli causes the appearance of specific sensations. These zones are present in the occipital (fields 17-19), parietal (zeros 1-3) and temporal (fields 21-22, 41-42) areas of the cortex.

In the sensory areas of the cortex, central projection fields are distinguished, providing a subtle, clear perception of sensations of certain modalities (light, sound, touch, heat, cold) and secondary projection fields. The function of the latter is to provide an understanding of the connection of the primary sensation with other objects and phenomena of the surrounding world.

The areas of representation of receptive fields in the sensory areas of the cortex largely overlap. A feature of the nerve centers in the area of ​​secondary projection fields of the cortex is their plasticity, which is manifested by the possibility of restructuring specialization and restoring functions after damage to any of the centers. These compensatory abilities of the nerve centers are especially pronounced in childhood. At the same time, damage to the central projection fields after suffering a disease is accompanied by a gross violation of the functions of sensitivity and often the impossibility of its recovery.

visual cortex

The primary visual cortex (VI, field 17) is located on both sides of the spur groove on the medial surface of the occipital lobe of the brain. In accordance with the identification of alternating white and dark stripes on unstained sections of the visual cortex, it is also called the striate (striated) cortex. The neurons of the lateral geniculate body send visual signals to the neurons of the primary visual cortex, which receive signals from the ganglion cells of the retina. The visual cortex of each hemisphere receives visual signals from the ipsilateral and contralateral halves of the retina of both eyes, and their flow to the neurons of the cortex is organized according to the somatotopic principle. Neurons that receive visual signals from photoreceptors are topographically located in the visual cortex, similar to receptors in the retina. At the same time, the area of ​​the macula of the retina has a relatively large zone of representation in the cortex than other areas of the retina.

The neurons of the primary visual cortex are responsible for visual perception, which, based on the analysis of input signals, is manifested by their ability to detect a visual stimulus, determine its specific shape and orientation in space. In a simplified way, it is possible to imagine the sensory function of the visual cortex in solving a problem and answering the question of what constitutes a visual object.

In the analysis of other qualities of visual signals (for example, location in space, movement, connection with other events, etc.), neurons of fields 18 and 19 of the extrastriate cortex, located adjacent to zero 17, take part. Information about the signals received by the sensory visual zones of the cortex, will be transferred for further analysis and use of vision to perform other brain functions in the associative areas of the cortex and other parts of the brain.

auditory cortex

It is located in the lateral sulcus of the temporal lobe in the region of the Heschl gyrus (AI, fields 41-42). The neurons of the primary auditory cortex receive signals from the neurons of the medial geniculate bodies. The fibers of the auditory pathways that conduct sound signals to the auditory cortex are organized tonotopically, and this allows cortical neurons to receive signals from certain auditory receptor cells in the organ of Corti. The auditory cortex regulates the sensitivity of auditory cells.

In the primary auditory cortex, sound sensations are formed and the individual qualities of sounds are analyzed to answer the question of what the perceived sound is. The primary auditory cortex plays an important role in the analysis of short sounds, intervals between sound signals, rhythm, sound sequence. More complex analysis sounds are carried out in the associative areas of the cortex adjacent to the primary auditory. Based on the interaction of neurons in these areas of the cortex, binaural hearing is carried out, the characteristics of pitch, timbre, sound volume, sound belonging are determined, and an idea of ​​a three-dimensional sound space is formed.

vestibular cortex

It is located in the upper and middle temporal gyri (fields 21-22). Its neurons receive signals from the neurons of the vestibular nuclei of the brain stem, connected by afferent connections with the receptors of the semicircular canals of the vestibular apparatus. In the vestibular cortex, a feeling is formed about the position of the body in space and the acceleration of movements. The vestibular cortex interacts with the cerebellum (through the temporo-pontocerebellar pathway), participates in the regulation of body balance, adaptation of the posture to the implementation of purposeful movements. Based on the interaction of this area with the somatosensory and associative areas of the cortex, awareness of the body schema occurs.

Olfactory cortex

It is located in the region of the upper part of the temporal lobe (hook, zeros 34, 28). The cortex includes a number of nuclei and belongs to the structures of the limbic system. Its neurons are located in three layers and receive afferent signals from the mitral cells of the olfactory bulb, connected by afferent connections with olfactory receptor neurons. In the olfactory cortex, a primary qualitative analysis of odors is carried out and a subjective sense of smell, its intensity, and belonging is formed. Damage to the cortex leads to a decrease in the sense of smell or to the development of anosmia - loss of smell. With artificial stimulation of this area, there are sensations of various smells like hallucinations.

taste bark

It is located in the lower part of the somatosensory gyrus, directly anterior to the face projection area (field 43). Its neurons receive afferent signals from relay neurons of the thalamus, which are associated with neurons in the nucleus of the solitary tract of the medulla oblongata. The neurons of this nucleus receive signals directly from sensory neurons that form synapses on the cells of the taste buds. In the taste cortex, a primary analysis of the taste qualities of bitter, salty, sour, sweet is carried out, and on the basis of their summation, a subjective sensation of taste, its intensity, and belonging is formed.

Smell and taste signals reach the neurons of the anterior insular cortex, where, based on their integration, a new, more complex quality of sensations is formed that determines our relationship to the sources of smell or taste (for example, to food).

Somatosensory cortex

It occupies the region of the postcentral gyrus (SI, fields 1-3), including the paracentral lobule on the medial side of the hemispheres (Fig. 9.14). The somatosensory area receives sensory signals from thalamic neurons connected by spinothalamic pathways with skin receptors (tactile, temperature, pain sensitivity), proprioceptors (muscle spindles, articular bags, tendons) and interoreceptors (internal organs).

Rice. 9.14. The most important centers and areas of the cerebral cortex

Due to the intersection of afferent pathways, signaling from the right side of the body comes to the somatosensory zone of the left hemisphere, respectively, in right hemisphere- from the left side of the body. In this sensory area of ​​the cortex, all parts of the body are somatotopically represented, but the most important receptive zones of the fingers, lips, skin of the face, tongue, and larynx occupy relatively larger areas than the projections of such body surfaces as the back, front of the torso, and legs.

The location of the representation of the sensitivity of body parts along the postcentral gyrus is often called the "inverted homunculus", since the projection of the head and neck is in the lower part of the postcentral gyrus, and the projection of the caudal part of the trunk and legs is in the upper part. In this case, the sensitivity of the legs and feet is projected onto the cortex of the paracentral lobule of the medial surface of the hemispheres. Within the primary somatosensory cortex there is a certain specialization of neurons. For example, field 3 neurons receive mainly signals from muscle spindles and mechanoreceptors of the skin, field 2 - from joint receptors.

The postcentral gyrus cortex is referred to as the primary somatosensory area (SI). Its neurons send processed signals to neurons in the secondary somatosensory cortex (SII). It is located posterior to the postcentral gyrus in the parietal cortex (fields 5 and 7) and belongs to the association cortex. SII neurons do not receive direct afferent signals from thalamic neurons. They are associated with SI neurons and neurons in other areas of the cerebral cortex. This makes it possible to carry out an integral assessment of signals entering the cortex along the spinothalamic pathway with signals coming from other (visual, auditory, vestibular, etc.) sensory systems. The most important function of these fields of the parietal cortex is the perception of space and the transformation of sensory signals into motor coordinates. In the parietal cortex, a desire (intention, impulse) to carry out a motor action is formed, which is the basis for the beginning of planning for the upcoming motor activity in it.

The integration of various sensory signals is associated with the formation of various sensations addressed to different parts of the body. These sensations are used both to form mental and other responses, examples of which can be movements with the simultaneous participation of the muscles of both sides of the body (for example, moving, feeling with both hands, grasping, unidirectional movement with both hands). The functioning of this area is necessary for recognizing objects by touch and determining the spatial location of these objects.

The normal function of the somatosensory areas of the cortex is an important condition for the formation of sensations such as heat, cold, pain and their addressing to a specific part of the body.

Damage to neurons in the area of ​​the primary somatosensory cortex leads to a decrease various kinds sensation on the opposite side of the body, and local damage - to loss of sensation in a certain part of the body. Discriminatory sensitivity of the skin is especially vulnerable when the neurons of the primary somatosensory cortex are damaged, and the least sensitive is pain. Damage to neurons in the secondary somatosensory area of ​​the cortex may be accompanied by a violation of the ability to recognize objects by touch (tactile agnosia) and skills in using objects (apraxia).

Motor areas of the cortex

About 130 years ago, researchers, applying point irritations to the cerebral cortex electric shock found that the impact on the surface of the anterior central gyrus causes contraction of the muscles of the opposite side of the body. Thus, the presence of one of the motor areas of the cerebral cortex was discovered. Subsequently, it turned out that several areas of the cerebral cortex and its other structures are related to the organization of movements, and in the areas of the motor cortex there are not only motor neurons, but also neurons that perform other functions.

primary motor cortex

primary motor cortex located in the anterior central gyrus (MI, field 4). Its neurons receive the main afferent signals from the neurons of the somatosensory cortex - fields 1, 2, 5, premotor cortex and thalamus. In addition, cerebellar neurons send signals to the MI via the ventrolateral thalamus.

Efferent fibers of the pyramidal pathway begin from the pyramidal neurons Ml. Part of the fibers of this path follows to the motor neurons of the nuclei cranial nerves brain stem (corticobulbar tract), part - to the neurons of the stem motor nuclei (red nucleus, nuclei of the reticular formation, stem nuclei associated with the cerebellum) and part - to the inter- and motor neurons of the spinal cord (corticospinal tract).

There is a somatotopic organization of the location of neurons in MI that control the contraction of different muscle groups of the body. The neurons that control the muscles of the legs and trunk are located in the upper parts of the gyrus and occupy a relatively small area, and the controlling muscles of the hands, especially the fingers, face, tongue and pharynx are located in the lower parts and occupy a large area. Thus, in the primary motor cortex, a relatively large area is occupied by those neural groups that control the muscles that carry out various, precise, small, finely regulated movements.

Since many Ml neurons increase electrical activity immediately before the onset of voluntary contractions, the primary motor cortex is assigned the leading role in controlling the activity of the motor nuclei of the trunk and spinal cord motoneurons and initiating voluntary, purposeful movements. Damage to the Ml field leads to muscle paresis and the impossibility of fine voluntary movements.

secondary motor cortex

Includes areas of the premotor and supplementary motor cortex (MII, field 6). premotor cortex located in field 6, on the lateral surface of the brain, anterior to the primary motor cortex. Its neurons receive afferent signals through the thalamus from the occipital, somatosensory, parietal associative, prefrontal areas of the cortex and cerebellum. The signals processed in it are sent by the neurons of the cortex along the efferent fibers to the motor cortex MI, a small number - to the spinal cord and more - to the red nuclei, the nuclei of the reticular formation, basal ganglia and cerebellum. The premotor cortex plays a major role in the programming and organization of movements under the control of vision. The cortex is involved in the organization of posture and auxiliary movements for the actions carried out by the distal muscles of the limbs. Damage to the visual cortex often causes a tendency to re-execute the initiated movement (perseveration), even if the completed movement has reached the goal.

In the lower part of the premotor cortex of the left frontal lobe, immediately anterior to the region of the primary motor cortex, in which the neurons that control the muscles of the face are represented, is located speech area, or motor center of Broca's speech. Violation of its function is accompanied by a violation of the articulation of speech, or motor aphasia.

Additional motor cortex located in the upper part of field 6. Its neurons receive afferent signals from the somatossensor, parietal and prefrontal areas of the cerebral cortex. The signals processed in it are sent by the neurons of the cortex along the efferent fibers to the primary motor cortex MI, the spinal cord, and the stem motor nuclei. The activity of the neurons of the supplementary motor cortex increases earlier than that of the neurons of the MI cortex, and mainly in connection with the implementation of complex movements. At the same time, an increase in neural activity in the additional motor cortex is not associated with movements as such; for this, it is enough to mentally imagine a model of upcoming complex movements. The supplementary motor cortex is involved in the formation of a program of upcoming complex movements and in the organization of motor reactions to the specificity of sensory stimuli.

Since the neurons of the secondary motor cortex send many axons to the MI field, it is considered a higher structure in the hierarchy of motor centers for organizing movements, standing above the motor centers of the MI motor cortex. The nerve centers of the secondary motor cortex can influence the activity of motor neurons in the spinal cord in two ways: directly through the corticospinal pathway and through the MI field. Therefore, they are sometimes called supramotor fields, whose function is to instruct the centers of the MI field.

From clinical observations, it is known that maintaining the normal function of the secondary motor cortex is important for the implementation of precise hand movements, and especially for the performance of rhythmic movements. So, for example, if they are damaged, the pianist ceases to feel the rhythm and maintain the interval. The ability to perform opposite hand movements (manipulation with both hands) is impaired.

With simultaneous damage to the motor areas MI and MII of the cortex, the ability to fine coordinated movements is lost. Point irritations in these areas of the motor zone are accompanied by activation not of individual muscles, but of a whole group of muscles that cause directed movement in the joints. These observations led to the conclusion that the motor cortex is represented not so much by muscles as by movements.

prefrontal cortex

It is located in the region of field 8. Its neurons receive the main afferent signals from the occipital visual, parietal associative cortex, superior colliculi of the quadrigemina. The processed signals are transmitted via efferent fibers to the premotor cortex, superior colliculus, and stem motor centers. The cortex plays a decisive role in the organization of movements under the control of vision and is directly involved in the initiation and control of eye and head movements.

The mechanisms that implement the transformation of the idea of ​​movement into a specific motor program, into bursts of impulses sent to certain muscle groups, remain insufficiently understood. It is believed that the idea of ​​movement is formed due to the functions of the associative and other areas of the cortex, interacting with many brain structures.

Information about the intention of movement is transmitted to the motor areas of the frontal cortex. The motor cortex, through descending pathways, activates systems that ensure the development and use of new motor programs or the use of old ones that have already been worked out in practice and stored in memory. An integral part of these systems are the basal ganglia and the cerebellum (see their functions above). Movement programs developed with the participation of the cerebellum and basal ganglia are transmitted through the thalamus to the motor areas and, above all, to the primary motor cortex. This area directly initiates the execution of movements, connecting certain muscles to it and providing a sequence of changes in their contraction and relaxation. Cortical commands are transmitted to the motor centers of the brain stem, spinal motor neurons and motor neurons of the cranial nerve nuclei. In the implementation of movements, motor neurons play the role of the final path through which motor commands are transmitted directly to the muscles. Features of signal transmission from the cortex to the motor centers of the stem and spinal cord are described in the chapter on the central nervous system (brain stem, spinal cord).

Association areas of the cortex

In humans, the associative areas of the cortex occupy about 50% of the area of ​​the entire cerebral cortex. They are located in the areas between the sensory and motor areas of the cortex. Associative areas do not have clear boundaries with secondary sensory areas, both in terms of morphological and functional features. Allocate parietal, temporal and frontal associative areas of the cerebral cortex.

Parietal association area of ​​the cortex. It is located in fields 5 and 7 of the upper and lower parietal lobes of the brain. The area borders in front of the somatosensory cortex, behind - with the visual and auditory cortex. Visual, sound, tactile, proprioceptive, pain, signals from the memory apparatus and other signals can enter and activate the neurons of the parietal associative area. Some neurons are polysensory and can increase their activity when they receive somatosensory and visual signals. However, the degree of increase in the activity of neurons in the associative cortex in response to afferent signals depends on the current motivation, the attention of the subject, and information retrieved from memory. It remains insignificant if the signal coming from the sensory areas of the brain is indifferent to the subject, and increases significantly if it coincided with the existing motivation and attracted his attention. For example, when a monkey is presented with a banana, the activity of neurons in the associative parietal cortex remains low if the animal is full, and vice versa, activity increases sharply in hungry animals that like bananas.

The neurons of the parietal association cortex are connected by efferent connections with the neurons of the prefrontal, premotor, motor areas of the frontal lobe and cingulate gyrus. Based on experimental and clinical observations, it is generally accepted that one of the functions of the field 5 cortex is the use of somatosensory information for the implementation of purposeful voluntary movements and manipulation of objects. The function of the field 7 cortex is the integration of visual and somatosensory signals to coordinate eye movements and visually guided hand movements.

Violation of these functions of the parietal associative cortex in case of damage to its connections with the cortex of the frontal lobe or disease of the frontal lobe itself, explains the symptoms of the consequences of diseases localized in the region of the parietal associative cortex. They can be manifested by difficulty in understanding the semantic content of signals (agnosia), an example of which may be the loss of the ability to recognize the shape and spatial location of an object. The processes of transformation of sensory signals into adequate motor actions may be disturbed. In the latter case, the patient loses skills in the practical use of well-known tools and objects (apraxia), and he may develop an inability to perform visually guided movements (for example, moving a hand in the direction of an object).

Frontal association area of ​​the cortex. It is located in the prefrontal cortex, which is part of the cortex of the frontal lobe, localized anterior to fields 6 and 8. The neurons of the frontal association cortex receive processed sensory signals via afferent connections from the neurons of the cortex of the occipital, parietal, temporal lobes of the brain and from the neurons of the cingulate gyrus. The frontal association cortex receives signals about the current motivational and emotional states from the nuclei of the thalamus, limbic and other brain structures. In addition, the frontal cortex can operate with abstract, virtual signals. The associative frontal cortex sends efferent signals back to the brain structures from which they were received, to the motor areas of the frontal cortex, the caudate nucleus of the basal ganglia, and the hypothalamus.

This area of ​​the cortex plays a primary role in the formation of higher mental functions of a person. It provides the formation of target settings and programs of conscious behavioral reactions, recognition and semantic evaluation of objects and phenomena, speech understanding, logical thinking. After extensive damage to the frontal cortex, patients may develop apathy, decreased emotional background, a critical attitude towards one's own actions and the actions of others, complacency, a violation of the possibility of using past experience to change behavior. The behavior of patients can become unpredictable and inadequate.

Temporal association area of ​​the cortex. It is located in fields 20, 21, 22. Cortical neurons receive sensory signals from neurons in the auditory, extrastriate visual and prefrontal cortex, hippocampus and amygdala.

After a bilateral disease of the temporal association areas with involvement of the hippocampus or connections with it in the pathological process, patients may develop severe memory impairment, emotional behavior, inability to concentrate (absent-mindedness). Some people with damage to the lower temporal region, where the center of face recognition is supposedly located, may develop visual agnosia - the inability to recognize the faces of familiar people, objects, while maintaining vision.

On the border of the temporal, visual and parietal areas of the cortex in the lower parietal and posterior part of the temporal lobe, there is an associative area of ​​the cortex, called sensory center of speech, or Wernicke's center. After its damage, a violation of the function of understanding speech develops while the speech motor function is preserved.

The cerebral cortex is present in the structure of the body of many creatures, but in humans it has reached its perfection. Scientists say that this became possible thanks to the age-old labor activity that accompanies us all the time. Unlike animals, birds or fish, a person is constantly developing his abilities and this improves his brain activity, including the functions of the cerebral cortex.

But, let's approach this gradually, first considering the structure of the crust, which is undoubtedly very exciting.

The internal structure of the cerebral cortex

The cerebral cortex has over 15 billion nerve cells and fibers. Each of them has a different shape, and form several unique layers responsible for certain functions. For example, the functionality of the cells of the second and third layers lies in the transformation of excitation and the correct redirection to certain parts of the brain. And, for example, centrifugal impulses represent the performance of the fifth layer. Let's take a closer look at each layer.

The numbering of the layers of the brain starts from the surface and goes deeper:

1. The molecular layer has a fundamental difference in its low level of cells. Their very limited number, consisting of nerve fibers are closely interconnected with each other.
2. The granular layer is otherwise called the outer layer. This is due to the presence of an inner layer.
3. The pyramidal level is named after its structure, because it has a pyramidal structure of neurons of various sizes.
4. The granular layer No. 2 is called the inner layer.
5. Pyramidal level No. 2 is similar to the third level. Its composition is the neurons of the pyramidal image having a medium and large size. They penetrate to the molecular level because it contains apical dendrites.
6. The sixth layer is fusiform cells, which have the second name "fusiform", which systematically pass into the white matter of the brain.

If we consider these levels in more depth, it turns out that the cerebral cortex takes on the projections of each level of excitation that occur in different parts of the central nervous system and are called "underlying". They, in turn, are transported to the brain via neural pathways human body.

Presentation: "Localization of higher mental functions in the cerebral cortex"

Thus, the cerebral cortex is the organ of the highest nervous activity human, and regulates absolutely all nervous processes occurring in the body.

And this happens due to the peculiarities of its structure, and it is divided into three zones: associative, motor and sensory.

Modern understanding of the structure of the cerebral cortex

It is worth noting that there is a somewhat different idea of ​​​​its structure. According to him, there are three zones that distinguish from each other not only the structure, but also its functional purpose.

• The primary zone (motor), in which its specialized and highly differentiated nerve cells are located, receives impulses from auditory, visual and other receptors. This is a very important area, the defeat of which can lead to serious disorders of motor and sensory function.
• The secondary (sensory) zone is responsible for the information processing functions. In addition, its structure consists of the peripheral sections of the analyzer nuclei, which establish the correct connections between stimuli. Her defeat threatens a man serious disorder perception.
• The associative, or tertiary zone, its structure allows it to be excited by impulses coming from the receptors of the skin, hearing, etc. It forms conditioned reflexes person, helping to cognize the surrounding reality.

Presentation: "Cerebral cortex"

Main functions

What is the difference between human and animal cerebral cortex? The fact that its purpose is to generalize all departments and control work. These functions provide billions of neurons with a diverse structure. These include such types as intercalary, afferent and efferent. Therefore, it will be relevant to consider each of these types in more detail.

The intercalated view of neurons has, at first glance, mutually exclusive functions, namely, inhibition and excitation.

The afferent type of neurons is responsible for impulses, or rather for their transmission. Efferent, in turn, provide a specific area of ​​human activity and refer to the periphery.

Of course, this is medical terminology and it is worth digressing from it, concretizing the functionality of the human cerebral cortex in a simple folk language. So, the cerebral cortex is responsible for the following functions:

• The ability to correctly establish a connection between internal organs and tissues. And what's more, it makes it perfect. This possibility is based on conditioned and unconditioned reflexes of the human body.
• Organization of the relationship between the human body and the environment. In addition, it controls the functionality of organs, corrects their work and is responsible for the metabolism in the human body.
• 100% responsible for ensuring that the thinking processes are correct.
• And last but not least important function- the highest level of nervous activity.

Having become acquainted with these functions, we come to understand that, which allowed each person and the whole family as a whole, to learn to control the processes that occur in the body.

Presentation: "Structural and functional characteristics of the sensory cortex"

Academician Pavlov, in his multiple studies, has repeatedly pointed out that it is the cortex that is both the manager and the distributor of human and animal activities.

But, it is also worth noting that the cerebral cortex has ambiguous functions. This is mainly manifested in the work of the central gyrus and the frontal lobes, which are responsible for muscle contraction on the side completely opposite to this irritation.

In addition, its different parts are responsible for different functions. For example, the occipital lobes are for visual, and the temporal lobes are for auditory functions:

• To be more specific, the occipital lobe of the cortex is actually a projection of the retina, which is responsible for its visual functions. If any violations occur in it, a person may lose orientation in an unfamiliar environment and even complete, irreversible blindness.
• The temporal lobe is an area of ​​auditory reception that receives impulses from the cochlea of ​​the inner ear, that is, is responsible for its auditory functions. Damage to this part of the cortex threatens a person with complete or partial deafness, which is accompanied by a complete misunderstanding of words.
• The lower lobe of the central gyrus is responsible for brain analyzers or, in other words, taste reception. She receives impulses from the oral mucosa and her defeat threatens to lose all taste sensations.
• And finally, the anterior part of the cerebral cortex, in which the piriform lobe is located, is responsible for olfactory reception, that is, the function of the nose. Impulses come into it from the nasal mucosa, if it is affected, then the person will lose his sense of smell.

It is not worth reminding once again that a person is at the highest stage of development.

This confirms the structure of a particularly developed frontal region, which is responsible for labor activity and speech. It is also important in the process of formation of human behavioral reactions and its adaptive functions.

There are many studies, including the work of the famous academician Pavlov, who worked with dogs, studying the structure and functioning of the cerebral cortex. All of them prove the advantages of man over animals, precisely due to its special structure.

True, one should not forget that all parts are in close contact with each other and depend on the work of each of its components, so that the perfection of a person is the key to the work of the brain as a whole.

From this article, the reader has already understood that the human brain is complex and still poorly understood. However, it is the perfect device. By the way, few people know that the power of processing processes in the brain is so high that next to it the most powerful computer in the world is powerless.

Here are some more interesting facts that scientists have published after a series of tests and studies:

• 2017 was marked by an experiment in which a hyper-powerful PC tried to simulate only 1 second of brain activity. The test took about 40 minutes. The result of the experiment - the computer did not cope with the task.
• The memory capacity of the human brain can accommodate the n-number bt, which is expressed by 8432 zeros. Approximately it is 1000 Tb. If on an example, then the historical information for the last 9 centuries is stored in the national British archive and its volume is only 70 Tb. Feel how significant the difference between these numbers is.
• The human brain contains 100 thousand kilometers of blood vessels, 100 billion neurons (a figure equal to the number of stars in our entire galaxy). In addition, there are one hundred trillion neural connections in the brain that are responsible for the formation of memories. Thus, when you learn something new, the structure of the brain changes.
• During awakening, the brain accumulates an electric field with a power of 23 W - this is enough to light Ilyich's lamp.
• By weight, the brain consists of 2% of the total mass, but it uses approximately 16% of the energy in the body and more than 17% of the oxygen in the blood.
• Another interesting fact is that the brain consists of 75% water, and the structure is somewhat similar to Tofu cheese. And 60% of the brain is fat. In view of this, for the correct functioning of the brain, a healthy and proper nutrition. Eat fish, olive oil, seeds or nuts every day and your brain will work long and clear.
• Some scientists, after conducting a series of studies, noticed that when dieting, the brain begins to “eat” itself. BUT low level oxygen for five minutes can lead to irreversible consequences.
• Surprisingly, a human being is not able to tickle himself, because. the brain tunes in to external stimuli and in order not to miss these signals, the actions of the person himself are slightly ignored.
• Forgetfulness is a natural process. That is, the elimination of unnecessary data allows the CNS to be flexible. And the effect of alcoholic beverages on memory is explained by the fact that alcohol slows down the processes.
• The brain's response to alcoholic beverages is six minutes.

The activation of the intellect allows the production of additional brain tissue that compensates for those that are sick. In view of this, it is recommended to engage in development, which in the future will save you from a weak mind and various mental disorders.

Engage in new activities - this is best for brain development. For example, communication with people who are superior to you in one or another intellectual field is a powerful tool for developing your intellect.

The cerebral cortex is the highest department of the central nervous system, which provides a perfect organization of human behavior. In fact, it predetermines consciousness, participates in the management of thinking, helps to ensure the relationship with the outside world and the functioning of the body. It establishes interaction with the outside world through reflexes, which allows you to properly adapt to new conditions.

The specified department is responsible for the work of the brain itself. On top of certain areas interconnected with the organs of perception, zones have formed that have subcortical white matter. They are important in complex data processing. Due to the appearance of such an organ in the brain, the next stage begins, at which the significance of its functioning increases significantly. This department is an organ that expresses the individuality and conscious activity of the individual.

General information about GM bark

It is a surface layer up to 0.2 cm thick, which covers the hemispheres. It provides for vertically oriented nerve endings. This organ contains centripetal and centrifugal nerve processes, neuroglia. Each share of this department is responsible for certain functions:

• - auditory function and sense of smell;
• occipital - visual perception;
• parietal - touch and taste buds;
• frontal - speech, motor activity, complex thought processes.

In fact, the cortex predetermines the conscious activity of the individual, participates in the control of thinking, and interacts with the outside world.

Anatomy

The functions performed by the cortex are often determined by its anatomical structure. The structure has its character traits, expressed in a different number of layers, dimensions, anatomy of the nerve endings that form the organ. Experts distinguish the following types of layers that interact with each other and help the system as a whole function:

• molecular layer. Helps to create chaotically connected dendritic formations with a small number of spindle-shaped cells and causing associative activity.
• outer layer. Expressed by neurons with different outlines. After them, the external contours of structures that have a pyramidal shape are localized.
• The outer layer is pyramidal. Assumes the presence of neurons of different sizes. In shape, these cells are similar to a cone. From above comes the dendrite, which has largest sizes. connected by dividing into minor formations.
• grainy layer. Provides for nerve endings of small size, localized apart.
• pyramid layer. Assumes the presence of neural circuits with different dimensions. The upper processes of neurons are able to reach the initial layer.
• An integument containing neural connections resembling a spindle. Some of them, located at the lowest point, can reach the level of white matter.
• frontal lobe
• Plays a key role in conscious activity. Participates in memorization, attention, motivation and other tasks.

It provides for the presence of 2 paired lobes and occupies 2/3 of the entire brain. The hemispheres control opposite sides of the body. So, left lobe regulates the work of the muscles of the right side and vice versa.

The frontal parts are important in subsequent planning, including management and decision making. In addition, they perform the following functions:

• Speech. Facilitates the expression of thought processes in words. Damage to this area can affect perception.
• Motility. Gives the opportunity to influence motor activity.
• comparative processes. Facilitates the classification of objects.
• Memorization. Each area of ​​the brain is important in the process of memorization. The frontal part forms long-term memory.
• Personal formation. It makes it possible to interact with impulses, memory and other tasks that form the main characteristics of the individual. The defeat of the frontal lobe radically changes the personality.
• Motivation. Most of the sensory nerve processes are located in the frontal part. Dopamine contributes to the maintenance of the motivational component.
• Attention control. If the frontal parts are not able to control attention, then an attention deficit syndrome is formed.

parietal lobe

It covers the upper and lateral parts of the hemisphere, and is also separated by a central groove. The functions that this site performs differ for the dominant and non-dominant sides:

• Dominant (mainly left). Responsible for the possibility of understanding the structure of the whole through the ratio of its components and for the synthesis of information. In addition, it enables the implementation of interrelated movements that are required to obtain a specific result.
• Non-dominant (predominantly right). A center that processes the data coming from the back of the head and provides a 3-dimensional perception of what is happening. The defeat of this area leads to the inability to recognize objects, faces, landscapes. Since visual images are processed in the brain separately from the data coming from other sense organs. In addition, the side takes part in the orientation in human space.

Both parietal parts are involved in the perception of temperature changes.

temporal

It implements a complex mental function - speech. It is located on both hemispheres from the side in the lower part, closely interacting with nearby departments. This part of the cortex has the most pronounced contours.

The temporal areas process auditory impulses, converting them into a sound image. They are important in providing verbal communication skills. Directly in this department, the recognition of the heard information takes place, the choice of language units for semantic expression.

To date, it has been confirmed that the occurrence of difficulties with smell in an elderly patient signals the emerging Alzheimer's disease.

A small area inside the temporal lobe () controls long-term memory. Directly temporal part accumulates memories. The dominant department interacts with verbal memory, the non-dominant one contributes to the visual memorization of images.

Simultaneous damage to two lobes leads to a serene state, loss of the ability to identify external images and increased sexuality.

Island

The islet (closed lobule) is located deep in the lateral furrow. The islet is separated from adjacent sections by a circular groove. The upper section of the closed lobule is divided into 2 parts. Here the taste analyzer is projected.

Forming the bottom of the lateral groove, the closed lobule is a protrusion, the upper part of which is directed outward. The islet is separated by a circular groove from the nearby lobes, which form the tegmentum.

The upper section of the closed lobule is divided into 2 parts. In the first, the precentral sulcus is localized, and the anterior central gyrus is located in the middle of them.

Furrows and convolutions

They are depressions and folds in the middle of them, which are localized on the surface of the cerebral hemispheres. Furrows contribute to an increase in the cortex of the hemispheres, without increasing the volume of the cranium.

The significance of these areas lies in the fact that two-thirds of the entire cortex is located deep in the furrows. There is an opinion that the hemispheres develop differently in different departments, as a result of this, the tension will also be uneven in specific areas. This can lead to the formation of folds or convolutions. Other scientists believe that the initial development of the furrows is of great importance.

The anatomical structure of the organ in question is distinguished by a variety of functions.

Each department of this body has a specific purpose, being a kind of level of influence.

Thanks to them, all the functioning of the brain is carried out. Violations in the work of a certain area can lead to malfunctions in the activity of the entire brain.

Pulse processing zone

This area contributes to the processing of nerve signals coming through visual receptors, smell, touch. Most of the reflexes associated with motor skills will be provided by pyramidal cells. The zone that provides the processing of muscle data is characterized by a well-coordinated interconnection of all layers of the organ, which is of key importance at the stage of the appropriate processing of nerve signals.

If the cerebral cortex is affected in this area, then disturbances can occur in the coordinated functioning of the functions and actions of perception, which are inextricably linked with motor skills. Outwardly, disorders in the motor part manifest themselves during involuntary motor activity, convulsions, severe manifestations that lead to paralysis.

Sensory zone

This area is responsible for processing impulses entering the brain. In its structure, it is a system of interaction of analyzers to establish a relationship with the stimulator. Experts distinguish 3 departments responsible for the perception of impulses. These include the occipital, which provides processing of visual images; temporal, which is associated with hearing; hippocampal area. The part that is responsible for processing these taste stimulants is located near the crown of the head. Here are the centers that are responsible for receiving and processing tactile impulses.

Sensory ability directly depends on the number of neural connections in this area. Approximately these sections occupy up to a fifth of the total size of the cortex. Damage to this area provokes improper perception, which will not allow the production of a counter impulse that would be adequate to the stimulus. For example, a disturbance in the functioning of the auditory zone does not cause deafness in all cases, but it can provoke some effects that distort the normal perception of data.

association zone

This department facilitates the contact between the impulses received by the neural connections in the sensory department and the motility, which is a counter signal. This part forms meaningful behavioral reflexes, and also takes part in their implementation. According to the location, the anterior zones are distinguished, located in the frontal parts, and the posterior ones, which have taken an intermediate position in the middle of the temples, the crown and the occipital region.

The individual is characterized by strongly developed posterior associative zones. These centers have a special purpose, guaranteeing the processing of speech impulses.

Pathological changes in the work of the anterior associative area lead to failures in analysis, prediction, based on previously experienced sensations.

Disorders in the functioning of the posterior associative area complicates spatial orientation, slows down abstract thought processes, the construction and identification of complex visual images.

The cerebral cortex is responsible for the functioning of the brain. This caused changes in the anatomical structure of the brain itself, as its work became much more complicated. On top of certain areas interconnected with the organs of perception and the motor apparatus, departments were formed that have associative fibers. They are necessary for the complex processing of data entering the brain. As a result of the formation of this organ, a new stage begins, where its significance increases significantly. This department is considered an organ that expresses the individual characteristics of a person and his conscious activity.