The cerebral cortex, its structure and significance. Cortex

The cerebral cortex is the highest division of the central nervous system. It is a thin layer of nervous tissue that forms many folds. The total surface area of ​​the bark is 2200 cm2. The thickness of the bark ranges from 1.3 to 4.5 mm. The volume of the cortex is approximately 600 cm3. The cerebral cortex includes 10 9 – 10 10 neurons and an even larger number of glial cells (Fig. 2.9). Within the cortex, there is an alternation of layers containing mainly the bodies of nerve cells with layers formed mainly by their axons, and therefore, in a fresh section, the cerebral cortex appears striped. Based on the shape and arrangement of nerve cells in the cortex, six layers can be distinguished with a typical structure; some are subdivided into two or more secondary layers. Based on the structure of the cortex, the following main zones are distinguished: new cortex (neocortex), old cortex (archicortex), ancient cortex (paleocortex) and intermediate cortex (periarchicortical and peripaleocortical). The largest zone of the cortex is the neocortex. The neocortex occupies the dorsal and lateral surface of the cerebral hemispheres, while the paleocortex is located on the basal and medial surface of the hemispheres.

Rice. 2.9. Cellular composition and layers of the cerebral cortex

The neocortex has the following layers:

I. Molecular layer (plexiform). This layer contains many fibers forming a dense tangential superficial plexus, but there are few cells in it. It contains mainly star-shaped small cells that carry out local integration of the activity of efferent neurons.

II. Outer granular layer. Contains small neurons of various shapes that have synaptic connections with neurons of the molecular layer throughout the entire diameter of the cortex. In its depths there are small pyramidal cells.

III. Outer pyramidal layer. This layer consists of pyramidal cells of small and medium size. Some sections of the cortex in this layer contain large pyramidal cells. There are especially many large pyramidal cells in the cortex of the anterior central gyrus. Some of the processes of these cells reach the first layer, participating in the formation of the tangential sublayer, others are immersed in the white matter of the cerebral hemispheres, therefore layer III is sometimes referred to as tertiary associative.

IV. Inner granular layer. It is characterized by a loose arrangement of small neurons of various sizes and shapes with a predominance of stellate ones having arcuate recurrent axons. Cell axons penetrate into the above and underlying layers. Stellate cells represent a system of switching from afferent to efferent neurons of layers III and IV. In layer IV, a tangential layer of nerve fibers is also formed. Therefore, sometimes this layer is designated as secondary projection-associative. The internal granular layer is the termination point of the bulk of the projection afferent fibers.

V. Inner pyramidal layer, or layer of nodal cells. Consists mainly of medium and large pyramidal cells. These neurons have long apical dendrites extending all the way to the molecular layer, as well as basal dendrites extending more or less tangentially to the surface. These layers are clearly expressed in the anterior central gyrus and only slightly in other areas of the cortex. From this layer, motor voluntary pathways (projection efferent fibers) are mainly formed.

VI. Layer of spindle cells (polymorphic, or multiform). This layer contains predominantly fusiform neurons, which have short convoluted apical dendrites ending in layers V and IV of the cortex. The axons of many cells in the layer unite into recurrent fibers, penetrating into layer V. The deep part of this layer passes into the white matter (Fig. 2.10).

Rice. 2.10. Layered structure of the cerebral cortex

It should be noted that the neurons of each cortical field have their own structural features. Cytoarchitectonic layers consist of nerve and glial cells (oligodendro-, astromacroglia) and numerous nerve fibers. The nerve fibers form dense plexuses called neuropil. Nerve cells are very diverse in their shape. There are up to 56 types of cortical cells. More generally, the most numerous pyramidal neurons are distinguished (giant Betz, large motor, medium, small), stellate and fusiform. The proportion of pyramidal cells among all cortical neurons ranges from 51 to 86%, stellate cells - from 8 to 47%, spindle-shaped neurons - from 2 to 6% (Fig. 2.9).

Functionally, the cortex contains predominantly excitatory neurons: pyramidal, stellate, Martinotti cells (inverted pyramids), glia-like and predominantly inhibitory: large basket-shaped, small basket-shaped, vertically oriented, fusiform. Connections between neurons are provided by numerous synapses and electrotonic contacts. Spine synapses are of great importance in the activity of the cortex. Thus, during the development of animals in an environment enriched with stimuli, compared to sensory deprivation, there is an increase in the number of spines on dendrites. Mental retardation and decreased learning ability due to chromosomal aberrations in humans are accompanied by a decrease in the number of spines. Electrotonic contacts are made in the cortex in 20% of cases. In addition, non-synaptic contacts between neurons have been described in the cortex; the functional purpose of such contacts remains unclear. In layers I, II there are predominantly dendro-spinous contacts, in layers III, IV - dendro-dendritic and somato-dendritic, in layer V - somato-soma-
tic and dendro-dendritic.

The American physiologist W. Mountcastle put forward a modular principle for the organization of cortical neurons. This principle is based on three starting points.

1. The cerebral cortex consists of complex numerous ensembles, the basic unit of which is formed by about a hundred vertically connected neurons of all layers of the cortex. This ensemble is called a mini-column. These mini-columns include: a) neurons that receive input neurons mainly from subcortical structures, for example, from specific sensory and motor nuclei of the thalamus; b) neurons receiving input signals from other areas of the cortex; c) all neurons of local networks forming vertical cellular columns; d) cells that transmit output signals from the column back to the thalamus, other areas of the cortex, and sometimes to cells of the limbic system.

2. Several of these fundamentally similar simple vertical ensembles can be combined using intercolumn connections into a larger unit that processes information - a module, or modular column. Despite the different density of neurons in the layers of different parts of the cortex, the general structure and functions of such modular columns are the same. These speakers differ only in the source of the input signals they receive and in the targets to which their output signals are addressed.

3. Mountcastle believes that the modules not only receive and process information, but also function together in extensive loops through which information leaving the columns is transmitted to other cortical and subcortical targets, and then returns back to the cortex. These loops ensure the orderly flow of information into cortical ensembles.

Neocortex connections

In the neocortex, there are several types of efferent and afferent connections.

Efferent fibers(corticofugal) can be:

1) projection fibers to subcortical formations (pathways: corticospinal, corticothalamic, corticopontine);

2) associative fibers that go to the same and neighboring areas of the cortex of the same hemisphere;

3) commissural fibers that connect the cortical areas of both hemispheres. The main commissures are the corpus callosum and the anterior thalamic commissure. The corpus callosum contains a lot of fibers. For example, in cats there are about 700 thousand fibers per 1 mm2.

Afferent fibers(cortico-petal) are associative, commissural and thalamocortical pathway - the main afferent pathway to the cortex from subcortical formations.

Afferent fibers end mainly in layers I-IV of the cortex. Based on this, it can be assumed that in the process of information processing, the superficial layers are mainly responsible for the perception and processing of cortico-petal signals. Particular importance in this process belongs to the fourth layer of the cortex.

Cell bodies of the most important efferent neurons the crusts lie predominantly in the deeper layers V-VI. They are considered the zone of origin of the efferent pathways of the cortex.

So, the area of ​​the cerebral cortex of one human hemisphere is about 800 - 2200 square meters. cm, thickness -- 1.5?5 mm. Most of the bark (2/3) lies deep in the furrows and is not visible from the outside. Thanks to this organization of the brain in the process of evolution, it was possible to significantly increase the area of ​​the cortex with a limited volume of the skull. The total number of neurons in the cortex can reach 10 - 15 billion.

The cerebral cortex itself is heterogeneous, therefore, in accordance with phylogeny (by origin), ancient cortex (paleocortex), old cortex (archicortex), intermediate (or middle) cortex (mesocortex) and new cortex (neocortex) are distinguished.

Ancient bark

Ancient bark, (or paleocortex)- This is the most simply structured cerebral cortex, which contains 2–3 layers of neurons. According to a number of famous scientists such as H. Fenish, R. D. Sinelnikov and Ya. R. Sinelnikov, indicating that the ancient cortex corresponds to the area of ​​the brain that develops from the piriform lobe, and the components of the ancient cortex are the olfactory tubercle and the surrounding cortex, including area of ​​the anterior perforated substance. The composition of the ancient cortex includes the following structural formations such as the prepiriform, periamygdala region of the cortex, the diagonal cortex and the olfactory brain, including the olfactory bulbs, the olfactory tubercle, the septum pellucidum, the nuclei of the septum pellucidum and the fornix.

According to M. G. Prives and a number of some scientists, the olfactory brain is topographically divided into two sections, including a number of formations and convolutions.

1. peripheral section (or olfactory lobe), which includes formations lying at the base of the brain:

olfactory bulb;

olfactory tract;

olfactory triangle (within which the olfactory tubercle is located, i.e., the apex of the olfactory triangle);

internal and lateral olfactory gyri;

internal and lateral olfactory stripes (the fibers of the internal stripe end in the subcallosal field of the paraterminal gyrus, the septum pellucidum and the anterior perforated substance, and the fibers of the lateral stripe end in the parahippocampal gyrus);

anterior perforated space or substance;

diagonal stripe, or Broca's stripe.

2. The central section includes three convolutions:

parahippocampal gyrus (hippocampal gyrus, or seahorse gyrus);

dentate gyrus;

cingulate gyrus (including its anterior part - the uncus).

Old and intermediate bark

Old bark (or archicortex)-- this cortex appears later than the ancient cortex and contains only three layers of neurons. It consists of the hippocampus (seahorse or Ammon's horn) with its base, the dentate gyrus and the cingulate gyrus. cortex brain neuron

Intermediate bark (or mesocortex)-- which is a five-layer cortex that separates the new cortex (neocortex) from the ancient cortex (paleocortex) and old cortex (archicortex) and because of this the middle cortex is divided into two zones:

• 1. peripaleocortical;
• 2. periarchiocortical.

According to V. M. Pokrovsky and G. A. Kuraev, the mesocortex includes the ostracic gyrus, as well as the parahippocampal gyrus in the entorhinal region bordering the old cortex and the prebase of the hippocampus.

According to R. D. Sinelnikov and Ya. R. Sinelnikov, the intermediate cortex includes such formations as the lower part of the insular lobe, the parahippocampal gyrus and the lower part of the limbic region of the cortex. But it is necessary to understand that the limbic region is understood as part of the new cortex of the cerebral hemispheres, which occupies the cingulate and parahippocampal gyri. There is also an opinion that the intermediate cortex is an incompletely differentiated zone of the insular cortex (or visceral cortex).

Due to the ambiguity of this interpretation of structures related to the ancient and old cortex, it has led to the advisability of using a combined concept as archiopaleocortex.

The structures of the archiopaleocortex have multiple connections, both among themselves and with other brain structures.

New crust

New bark (or neocortex)- phylogenetically, i.e. in its origin - this is the most recent formation of the brain. Due to the later evolutionary emergence and rapid development of the new cerebral cortex in its organization of complex forms of higher nervous activity and its highest hierarchical level, which is vertically coordinated with the activity of the central nervous system, constituting the most features of this part of the brain. The features of the neocortex have attracted and continue to hold the attention of many researchers studying the physiology of the cerebral cortex for many years. Currently, old ideas about the exclusive participation of the neocortex in the formation of complex forms of behavior, including conditioned reflexes, have been replaced by the idea of ​​it as the highest level of thalamocortical systems functioning together with the thalamus, limbic and other brain systems. The neocortex is involved in the mental experience of the external world - its perception and the creation of its images, which are preserved for a more or less long time.

A feature of the structure of the neocortex is the screen principle of its organization. The main thing in this principle - the organization of neural systems is the geometric distribution of projections of higher receptor fields on a large surface of the neuronal field of the cortex. Also characteristic of the screen organization is the organization of cells and fibers that run perpendicular to the surface or parallel to it. This orientation of cortical neurons provides opportunities for combining neurons into groups.

As for the cellular composition in the neocortex, it is very diverse, the size of neurons is approximately from 8–9 μm to 150 μm. The vast majority of cells belong to two types: pararamid and stellate. The neocortex also contains spindle-shaped neurons.

In order to better examine the features of the microscopic structure of the cerebral cortex, it is necessary to turn to architectonics. Under the microscopic structure, cytoarchitectonics (cellular structure) and myeloarchitectonics (fibrous structure of the cortex) are distinguished. The beginning of the study of the architectonics of the cerebral cortex dates back to the end of the 18th century, when in 1782 Gennari first discovered the heterogeneity of the structure of the cortex in the occipital lobes of the hemispheres. In 1868, Meynert divided the diameter of the cerebral cortex into layers. In Russia, the first researcher of the bark was V. A. Betz (1874), who discovered large pyramidal neurons in the 5th layer of the cortex in the area of ​​the precentral gyrus, named after him. But there is another division of the cerebral cortex - the so-called Brodmann field map. In 1903, the German anatomist, physiologist, psychologist and psychiatrist K. Brodmann published a description of fifty-two cytoarchitectonic fields, which are areas of the cerebral cortex that differ in their cellular structure. Each such field differs in size, shape, location of nerve cells and nerve fibers and, of course, different fields are associated with different functions of the brain. Based on the description of these fields, a map of 52 Brodman fields was compiled

The cortex works in conjunction with other structures. This part of the organ has certain features associated with its specific activity. The main basic function of the cortex is to analyze information received from the organs and store the received data, as well as their transmission to other parts of the body. The cerebral cortex communicates with information receptors, which act as receivers of signals entering the brain.

Among the receptors there are sensory organs, as well as organs and tissues that carry out commands, which, in turn, are transmitted from the cortex.

For example, visual information coming from is sent along nerves through the cortex to the occipital zone, which is responsible for vision. If the image is not static, it is analyzed in the parietal zone, in which the direction of movement of the observed objects is determined. The parietal lobes are also involved in the formation of articulate speech and a person’s perception of his location in space. The frontal lobes of the cerebral cortex for higher mental functions involved in the formation of personality, character, abilities, behavioral skills, creative inclinations, etc.

Lesions of the cerebral cortex

When one or another part of the cerebral cortex is damaged, disturbances occur in the perception and functioning of certain human sensory organs.

With lesions of the frontal lobe of the brain, mental disorders occur, which most often manifest themselves in serious impairment of attention, apathy, weakening of memory, sloppiness and a feeling of constant euphoria. A person loses some personal qualities and develops serious behavioral deviations. Frontal ataxia often occurs and manifests as difficulty standing or walking, difficulty moving, problems with accuracy, and the occurrence of hit-and-miss phenomena. The phenomenon of grasping may also occur, which consists of obsessively grasping objects surrounding a person. Some scientists associate the appearance of epileptic seizures precisely after injury to the frontal lobe.

When the frontal lobe is damaged, a person’s mental abilities are significantly impaired.

With lesions of the parietal lobe, memory disorders are observed. For example, astereognosis may occur, which manifests itself in the inability to recognize an object by touch when closing the eyes. Apraxia often appears, manifested in a violation of the formation of a sequence of events and the building of a logical chain for performing a motor task. Alexia is characterized by the inability to read. Acalculia is a violation of the ability to carry out operations with numbers. There may also be impaired perception of one's own body in space and an inability to understand logical structures.

The affected temporal lobes are responsible for hearing and perception disorders. With lesions of the temporal lobe, the perception of oral speech is impaired, attacks of dizziness, hallucinations and seizures, mental disorders and excessive irritation begin. Injuries to the occipital lobe cause visual hallucinations and disturbances, the inability to recognize objects when looking at them, and distorted perception of the shape of an object. Sometimes photoms appear - flashes of light that occur when the inner part of the occipital lobe is irritated.

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

This department is responsible for the functioning of the brain itself. On top of certain areas interconnected with the organs of perception, zones with subcortical white matter were formed. They are important for complex data processing. As a result of the appearance of such an organ in the brain, the next stage begins, at which the importance 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 superficial layer up to 0.2 cm thick that covers the hemispheres. It provides 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 own characteristic features, expressed in a different number of layers, dimensions, and anatomy of the nerve endings that form the organ. Experts identify the following types of layers that interact with each other and help the system as a whole function:

• Molecular layer. Helps create chaotically connected dendritic formations with a small number of spindle-shaped cells that determine associative activity.
• Outer layer. Expressed by neurons having different outlines. After them, the external contours of structures having a pyramidal shape are localized.
• The outer layer is pyramidal. Assumes the presence of neurons of different sizes. These cells are similar in shape to a cone. The largest dendrite emerges from the top. connected by division into minor entities.
• Granular layer. Provides nerve endings of small size, localized separately.
• Pyramidal layer. It assumes the presence of neural circuits of different sizes. The upper processes of neurons are able to reach the initial layer.
• A covering 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 for conscious activity. Participates in memory, attention, motivation and other tasks.

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, the left lobe regulates the work of the muscles on the right side and vice versa.

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

• Speech. Helps express thought processes in words. Damage to this area can affect perception.
• Motor skills. Allows you to influence physical activity.
• Comparative processes. Contributes to the classification of objects.
• Memorization. Each area of ​​the brain is important in memory processes. 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 an individual. Damage to the frontal lobe radically changes personality.
• Motivation. Most of the sensory nerve processes are located in the frontal part. Dopamine helps maintain the motivational component.
• Attention control. If the frontal parts are not able to control attention, then attention deficit syndrome is formed.

Parietal lobe

Covers the upper and lateral parts of the hemisphere, and is also separated by the central sulcus. The functions that this area performs differ for the dominant and non-dominant sides:

• Dominant (mostly left). Responsible for the ability to understand the structure of the whole through the relationship of its components and for the synthesis of information. In addition, it makes it possible to carry out interrelated movements that are required to obtain a specific result.
• Non-dominant (predominantly right-wing). A center that processes data coming from the back of the head and provides a 3-dimensional perception of what is happening. Damage to this area leads to the inability to recognize objects, faces, and landscapes. Since visual images are processed in the brain separately from data coming from other senses. In addition, the side takes part in the orientation of a person in 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 in the lateral lower part, closely interacting with nearby sections. 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 heard information and the selection of linguistic units for semantic expression occur.

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

A small area inside the temporal lobe () controls long-term memory. The immediate temporal part accumulates memories. The dominant department interacts with verbal memory, the non-dominant one promotes 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 insula (closed lobule) is located deep in the lateral sulcus. The insula is separated from adjacent sections by a circular groove. The upper section of the closed lobule is divided into 2 parts. The taste analyzer is projected here.

Forming the bottom of the lateral sulcus, the closed lobule is a projection, the upper part of which is directed outward. The insula is separated by a circular groove from nearby lobes that form the operculum.

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

Furrows and convolutions

They are depressions and folds located in the middle of them, which are localized on the surface of the cerebral hemispheres. The grooves contribute to the enlargement of the cerebral cortex 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 grooves. There is an opinion that the hemispheres develop unequally in different departments, as a result of which the tension will also be uneven in specific areas. This can lead to the formation of folds or wrinkles. 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 its variety of functions.

Each department of this organ has a specific purpose, being a unique level of influence.

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

Pulse processing area

This area facilitates the processing of nerve signals coming through visual receptors, smell, and touch. Most reflexes associated with motor skills will be provided by pyramidal cells. The zone that processes muscle data is characterized by a harmonious interconnection of all layers of the organ, which is of key importance at the stage of corresponding processing of nerve signals.

If the cerebral cortex is affected in this area, then disturbances may occur in the coordinated functioning of the functions and actions of perception, which are inextricably linked with motor skills. Externally, disorders in the motor part manifest themselves during involuntary motor activity, convulsions, and 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 between analyzers to establish a relationship with the stimulator. Experts identify 3 departments responsible for the perception of impulses. These include the occipital region, 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 next to the crown. 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 inappropriate perception, which will not allow the production of a counter impulse that would be adequate to the stimulus. For example, a disruption in the functioning of the auditory zone does not in all cases cause deafness, but it can provoke some effects that distort the normal perception of data.

Association zone

This department facilitates contact between impulses received by neural connections in the sensory department and motor activity, which is a counter signal. This part forms meaningful behavioral reflexes and also takes part in their implementation. Based on their location, the anterior zones are distinguished, located in the frontal parts, and the posterior zones, which occupy an intermediate position in the middle of the temples, crown and occipital area.

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

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

Disorders in the functioning of the posterior associative area complicate spatial orientation, slow down abstract thought processes, and 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 significantly more complicated. On top of certain areas interconnected with the organs of perception and the motor apparatus, sections have formed that have associative fibers. They are necessary for complex processing of data entering the brain. Due to 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.

Shoshina Vera Nikolaevna

Therapist, education: Northern Medical University. Work experience 10 years.

Articles written

The brain of modern man and its complex structure is the greatest achievement of this species and its advantage, unlike other representatives of the living world.

The cerebral cortex is a very thin layer of gray matter that does not exceed 4.5 mm. It is located on the surface and sides of the cerebral hemispheres, covering them on top and along the periphery.

The anatomy of the cortex, or cortex, is complex. Each area performs its own function and plays a huge role in the implementation of nervous activity. This site can be considered the highest achievement of the physiological development of mankind.

Structure and blood supply

The cerebral cortex is a layer of gray matter cells that makes up approximately 44% of the total volume of the hemisphere. The area of ​​the average person's cortex is about 2200 square centimeters. The structural features in the form of alternating grooves and convolutions are designed to maximize the size of the cortex and at the same time fit compactly within the cranium.

Interestingly, the pattern of convolutions and furrows is as individual as the prints of papillary lines on a person’s fingers. Each individual is individual in pattern and pattern.

The cerebral cortex consists of the following surfaces:

1. Superolateral. It is adjacent to the inside of the skull bones (vault).
2. Bottom. Its anterior and middle sections are located on the inner surface of the base of the skull, and the posterior sections rest on the tentorium of the cerebellum.
3. Medial. It is directed to the longitudinal fissure of the brain.

The most prominent places are called poles - frontal, occipital and temporal.

The cerebral cortex is symmetrically divided into lobes:

• frontal;
• temporal;
• parietal;
• occipital;
• insular.

The structure includes the following layers of the human cerebral cortex:

• molecular;
• external granular;
• layer of pyramidal neurons;
• internal granular;
• ganglion, internal pyramidal or Betz cell layer;
• layer of multiformat, polymorphic or spindle-shaped cells.

Each layer is not a separate independent formation, but represents a single coherently functioning system.

Functional areas

Neurostimulation has revealed that the cortex is divided into the following sections of the cerebral cortex:

1. Sensory (sensitive, projection). They receive incoming signals from receptors located in various organs and tissues.
2. Motors send outgoing signals to effectors.
3. Associative, processing and storing information. They evaluate previously obtained data (experience) and issue an answer taking them into account.

The structural and functional organization of the cerebral cortex includes the following elements:

• visual, located in the occipital lobe;
• auditory, occupying the temporal lobe and part of the parietal lobe;
• the vestibular one has been studied to a lesser extent and still poses a problem for researchers;
• the olfactory one is on the bottom;
• gustatory is located in the temporal regions of the brain;
• the somatosensory cortex appears in the form of two areas - I and II, located in the parietal lobe.

Such a complex structure of the cortex suggests that the slightest violation will lead to consequences that affect many functions of the body and cause pathologies of varying intensity, depending on the depth of the lesion and the location of the area.

How is the cortex connected to other parts of the brain?

All zones of the human cerebral cortex do not exist separately; they are interconnected and form inextricable bilateral chains with deeper brain structures.

The most important and significant connection is the cortex and thalamus. In case of a skull injury, the damage is much more significant if the thalamus is also injured along with the cortex. Injuries to the cortex alone are detected much less frequently and have less significant consequences for the body.

Almost all connections from different parts of the cortex pass through the thalamus, which gives grounds to unite these parts of the brain into the thalamocortical system. Interruption of connections between the thalamus and cortex leads to loss of functions of the corresponding part of the cortex.

Pathways from sensory organs and receptors to the cortex also pass through the thalamus, with the exception of some olfactory pathways.

Interesting facts about the cerebral cortex

The human brain is a unique creation of nature, which the owners themselves, that is, people, have not yet learned to fully understand. It is not entirely fair to compare it with a computer, because now even the most modern and powerful computers cannot cope with the volume of tasks performed by the brain within a second.

We are accustomed to not paying attention to the usual functions of the brain associated with maintaining our daily life, but if even the slightest disruption occurred in this process, we would immediately feel it “in our own skin.”

“Little gray cells,” as the unforgettable Hercule Poirot said, or from the point of view of science, the cerebral cortex is an organ that still remains a mystery to scientists. We have found out a lot, for example, we know that the size of the brain does not in any way affect the level of intelligence, because the recognized genius - Albert Einstein - had a brain mass below average, about 1230 grams. At the same time, there are creatures that have a brain of a similar structure and even larger size, but have never reached the level of human development.

A striking example is the charismatic and intelligent dolphins. Some people believe that once in ancient times the tree of life split into two branches. Our ancestors passed along one path, and dolphins along the other, that is, we may have had common ancestors with them.

A feature of the cerebral cortex is its irreplaceability. Although the brain is able to adapt to injury and even partially or completely restore its functionality, when part of the cortex is lost, the lost functions are not restored. Moreover, scientists were able to conclude that this part largely determines a person’s personality.

If the frontal lobe is injured or there is a tumor here, after surgery and removal of the destroyed area of ​​the cortex, the patient changes radically. That is, the changes concern not only his behavior, but also the personality as a whole. There have been cases when a good, kind person turned into a real monster.

Based on this, some psychologists and criminologists have concluded that prenatal damage to the cerebral cortex, especially the frontal lobe, leads to the birth of children with antisocial behavior and sociopathic tendencies. Such kids have a high chance of becoming a criminal and even a maniac.

CGM pathologies and their diagnosis

All disorders of the structure and functioning of the brain and its cortex can be divided into congenital and acquired. Some of these lesions are incompatible with life, for example, anencephaly - complete absence of the brain and acrania - absence of cranial bones.

Other diseases leave a chance for survival, but are accompanied by mental development disorders, for example, encephalocele, in which part of the brain tissue and its membranes protrudes out through an opening in the skull. An underdeveloped small brain, accompanied by various forms of mental retardation (mental retardation, idiocy) and physical development, also falls into this group.

A rarer variant of the pathology is macrocephaly, that is, enlargement of the brain. The pathology is manifested by mental retardation and seizures. With it, the enlargement of the brain can be partial, that is, asymmetrical hypertrophy.

Pathologies that affect the cerebral cortex are represented by the following diseases:

1. Holoprosencephaly is a condition in which the hemispheres are not separated and there is no complete division into lobes. Children with this disease are stillborn or die within the first day after birth.
2. Agyria is underdevelopment of the gyri, in which the functions of the cortex are disrupted. Atrophy is accompanied by multiple disorders and leads to the death of the infant during the first 12 months of life.
3. Pachygyria is a condition in which the primary gyri are enlarged to the detriment of the others. The furrows are short and straightened, the structure of the cortex and subcortical structures is disrupted.
4. Micropolygyria, in which the brain is covered with small convolutions, and the cortex has not 6 normal layers, but only 4. The condition can be diffuse and local. Immaturity leads to the development of plegia and muscle paresis, epilepsy, which develops in the first year, and mental retardation.
5. Focal cortical dysplasia is accompanied by the presence of pathological areas in the temporal and frontal lobes with huge neurons and abnormal ones. Improper cell structure leads to increased excitability and seizures accompanied by specific movements.
6. Heterotopia is an accumulation of nerve cells that during development did not reach their place in the cortex. A single condition can appear after the age of ten; large clusters cause attacks such as epileptic seizures and mental retardation.

Acquired diseases are mainly consequences of serious inflammation, trauma, and also appear after the development or removal of a tumor - benign or malignant. In such conditions, as a rule, the impulse emanating from the cortex to the corresponding organs is interrupted.

The most dangerous is the so-called prefrontal syndrome. This area is actually the projection of all human organs, therefore damage to the frontal lobe leads to memory, speech, movements, thinking, as well as partial or complete deformation and changes in the patient’s personality.

A number of pathologies accompanied by external changes or deviations in behavior are quite easy to diagnose, others require more careful study, and removed tumors are subjected to histological examination to exclude a malignant nature.

Alarming indications for the procedure are the presence of congenital pathologies or diseases in the family, fetal hypoxia during pregnancy, asphyxia during childbirth, or birth trauma.

Methods for diagnosing congenital abnormalities

Modern medicine helps prevent the birth of children with severe malformations of the cerebral cortex. To do this, screening is performed in the first trimester of pregnancy, which makes it possible to identify pathologies in the structure and development of the brain at the earliest stages.

In a newborn baby with suspected pathology, neurosonography is performed through the “fontanel,” and older children and adults are examined by conducting. This method allows not only to detect a defect, but also to visualize its size, shape and location.

If there are hereditary problems in the family related to the structure and functioning of the cortex and the entire brain, consultation with a geneticist and specific examinations and tests are required.

The famous “gray cells” are the greatest achievement of evolution and the greatest benefit for humans. Damage can be caused not only by hereditary diseases and injuries, but also by acquired pathologies provoked by the person himself. Doctors urge you to take care of your health, give up bad habits, allow your body and brain to rest and not let your mind get lazy. Loads are useful not only for muscles and joints - they do not allow nerve cells to age and fail. Those who study, work and exercise their brain suffer less from wear and tear and later come to a loss of mental abilities.