The structure of the cerebral cortex. Structures of the limbic system and neocortex New cortex

So, the area of the cerebral cortex of one hemisphere of a person is about 800 - 2200 square meters. see, 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), the ancient cortex (paleocortex), the old cortex (archicortex), the intermediate (or middle) cortex (mesocortex) and the new cortex (neocortex) are distinguished.

ancient bark

Ancient bark, (or paleocortex)- this is the most simple structure of the cerebral cortex, which contains 2-3 layers of neurons. According to a number of well-known scientists such as H. Fenish, R. D. Sinelnikov and Ya. R. Sinelnikov, who indicate that the ancient cortex corresponds to the region 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 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 on the basis of the brain:

olfactory bulb;

olfactory tract;

olfactory triangle (inside which is the olfactory tubercle, i.e., the top of the olfactory triangle);

internal and lateral olfactory gyrus;

internal and lateral olfactory strips (the fibers of the internal strip end in the subcausal field of the paraterminal gyrus, the transparent septum and in the anterior perforated substance, and the fibers of the lateral strip end in the parahippocampal gyrus);

anterior perforated space, or substance;

diagonal stripe, or Broca's strip.

2. the central department includes three convolutions:

parahippocampal gyrus (hippocampal gyrus, or seahorse gyrus);

dentate gyrus;

cingulate gyrus (including its anterior part - hook).

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 horn) with its base, dentate gyrus and cingulate gyrus. cerebral cortex neuron

Intermediate bark (or mesocortex)-- representing a five-layer fate of the cortex, separating the new cortex (neocortex), from the ancient cortex (paleocortex) and the 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 composition of the mesocortex includes the ostrave, as well as in the entorial region, the parahippocampal gyrus bordering on the old cortex and the pre-basement 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 at the same time, 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 gyrus. There is also an opinion that the intermediate cortex is an incompletely differentiated zone of the cortex of the island (or visceral cortex).

Due to the ambiguity of such an interpretation of the structures related to the ancient and old crust, it has translated into the expediency of using the combined concept as the archiopaleocortex.

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

New bark

New bark (or neocortex)- phylogenetically, that is, in its origin - this is the latest 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, while constituting the most features of this part of the brain. For many years, the features of the neocortex have attracted and continue to hold the attention of many researchers studying the physiology of the cerebral cortex. At present, the old ideas about the monopoly participation of the new cortex 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 creation of its images, which persist for a more or less long time.

A feature of the structure of the new cortex 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 for the screen organization is the characteristic 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 groupings.

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 - pramid and stellate. There are also spindle-shaped neurons in the neocortex.

In order to better consider 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, Meinert divided the diameter of the cerebral cortex into layers. In Russia, the first researcher of the cortex was V. A. Betz (1874), who discovered large pyramidal neurons in the 5th layer of the cortex in the region 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. Brodman published a description of fifty-two cytoarchitectonic fields, which are sections 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 cerebral cortex is the center of higher nervous (mental) human activity and controls the implementation of a huge number of vital functions and processes. It covers the entire surface of the cerebral hemispheres and occupies about half of their volume.

The cerebral hemispheres occupy about 80% of the volume of the cranium, and are composed of white matter, the basis of which consists of long myelinated axons of neurons. Outside, the hemisphere is covered with gray matter or the cerebral cortex, consisting of neurons, non-myelinated fibers and glial cells, which are also contained in the thickness of the departments of this organ.

The surface of the hemispheres is conditionally divided into several zones, the functionality of which is to control the body at the level of reflexes and instincts. It also contains centers of higher mental activity of a person, which provide consciousness, assimilation of the information received, allowing one to adapt to the environment, and through it, at the subconscious level, the autonomic nervous system (ANS) is controlled by the hypothalamus, which controls the organs of blood circulation, respiration, digestion, excretion , reproduction, and metabolism.

In order to understand what the cerebral cortex is and how its work is carried out, it is required to study the structure at the cellular level.

Functions

The cortex occupies most of the cerebral hemispheres, and its thickness is not uniform over the entire surface. This feature is due to the large number of connecting channels with the central nervous system (CNS), which ensure the functional organization of the cerebral cortex.

This part of the brain begins to form during fetal development and improves throughout life, by receiving and processing signals from the environment. Thus, it is responsible for the following functions of the brain:

connects the organs and systems of the body with each other and the environment, and also provides an adequate response to changes;
processes the information received from the motor centers with the help of mental and cognitive processes;
consciousness, thinking are formed in it, and intellectual work is also realized;
controls the speech centers and processes that characterize the psycho-emotional state of a person.

At the same time, data is received, processed, and stored due to a significant number of impulses that pass through and are formed in neurons connected by long processes or axons. The level of cell activity can be determined by the physiological and mental state of the body and described using amplitude and frequency indicators, since the nature of these signals is similar to electrical impulses, and their density depends on the area in which the psychological process occurs.

It is still unclear how the frontal part of the cerebral cortex affects the functioning of the body, but it is known that it is not very susceptible to processes occurring in the external environment, therefore, all experiments with the impact of electrical impulses on this part of the brain do not find a clear response in the structures . However, it is noted that people whose frontal part is damaged experience problems in communicating with other individuals, cannot realize themselves in any work activity, and they are indifferent to their appearance and third-party opinions. Sometimes there are other violations in the implementation of the functions of this body:

lack of concentration on household items;
manifestation of creative dysfunction;
violations of the psycho-emotional state of a person.

The surface of the cerebral cortex is divided into 4 zones, outlined by the most clear and significant convolutions. Each of the parts at the same time controls the main functions of the cerebral cortex:

parietal zone - responsible for active sensitivity and musical perception;
in the back of the head is the primary visual area;
the temporal or temporal is responsible for the speech centers and the perception of sounds coming from the external environment, in addition, it is involved in the formation of emotional manifestations, such as joy, anger, pleasure and fear;
the frontal zone controls motor and mental activity, and also controls speech motor skills.

Features of the structure of the cerebral cortex

The anatomical structure of the cerebral cortex determines its features and allows it to perform the functions assigned to it. The cerebral cortex has the following number of distinctive features:

neurons in its thickness are arranged in layers;
nerve centers are located in a specific place and are responsible for the activity of a certain part of the body;
the level of activity of the cortex depends on the influence of its subcortical structures;
it has connections with all underlying structures of the central nervous system;
the presence of fields of different cellular structure, which is confirmed by histological examination, while each field is responsible for the performance of any higher nervous activity;
the presence of specialized associative areas makes it possible to establish a causal relationship between external stimuli and the body's response to them;
the ability to replace damaged areas with nearby structures;
this part of the brain is able to store traces of excitation of neurons.

The large hemispheres of the brain consist mainly of long axons, and also contains clusters of neurons in its thickness, forming the largest nuclei of the base, which are part of the extrapyramidal system.

As already mentioned, the formation of the cerebral cortex occurs even during intrauterine development, and at first the cortex consists of the lower layer of cells, and already at 6 months of the child all structures and fields are formed in it. The final formation of neurons occurs by the age of 7, and the growth of their bodies is completed at 18 years of age.

An interesting fact is that the thickness of the cortex is not uniform throughout and includes a different number of layers: for example, in the region of the central gyrus, it reaches its maximum size and has all 6 layers, and areas of the old and ancient cortex have 2 and 3 layers. x layer structure, respectively.

The neurons of this part of the brain are programmed to repair the damaged area through synoptic contacts, thus each of the cells actively tries to repair the damaged connections, which ensures the plasticity of neural cortical networks. For example, when the cerebellum is removed or dysfunction, the neurons that connect it with the final section begin to grow into the cerebral cortex. In addition, the plasticity of the cortex also manifests itself under normal conditions, when a process of learning a new skill takes place or as a result of pathology, when the functions performed by the damaged area are transferred to neighboring parts of the brain or even the hemisphere.

The cerebral cortex has the ability to retain traces of neuronal excitation for a long time. This feature allows you to learn, remember and respond with a certain reaction of the body to external stimuli. This is how the formation of a conditioned reflex occurs, the nervous path of which consists of 3 devices connected in series: an analyzer, a closing apparatus of conditioned reflex connections and a working device. Weakness of the closing function of the cortex and trace manifestations can be observed in children with severe mental retardation, when the conditioned connections formed between neurons are fragile and unreliable, which leads to learning difficulties.

The cerebral cortex includes 11 areas, consisting of 53 fields, each of which is assigned a number in neurophysiology.

Areas and zones of the cortex

The cortex is a relatively young part of the CNS, developed from the terminal part of the brain. The evolutionary formation of this organ occurred in stages, so it is usually divided into 4 types:

The archicortex or ancient cortex, due to atrophy of the sense of smell, has turned into a hippocampal formation and consists of the hippocampus and its associated structures. It regulates behavior, feelings and memory.
The paleocortex, or old cortex, makes up the bulk of the olfactory zone.
The neocortex or neocortex is about 3-4 mm thick. It is a functional part and performs higher nervous activity: it processes sensory information, gives motor commands, and it also forms conscious thinking and speech of a person.
The mesocortex is an intermediate variant of the first 3 types of cortex.

Physiology of the cerebral cortex

The cerebral cortex has a complex anatomical structure and includes sensory cells, motor neurons and internerons that have the ability to stop the signal and be excited depending on the received data. The organization of this part of the brain is built on a columnar principle, in which the columns are made into micromodules that have a homogeneous structure.

The system of micromodules is based on stellate cells and their axons, while all neurons respond in the same way to an incoming afferent impulse and also send an efferent signal synchronously in response.

The formation of conditioned reflexes that ensure the full functioning of the body occurs due to the connection of the brain with neurons located in various parts of the body, and the cortex ensures the synchronization of mental activity with the motility of organs and the area responsible for the analysis of incoming signals.

Signal transmission in the horizontal direction occurs through transverse fibers located in the thickness of the cortex, and transmit an impulse from one column to another. According to the principle of horizontal orientation, the cerebral cortex can be divided into the following areas:

associative;
sensory (sensitive);
motor.

When studying these zones, various methods of influencing the neurons included in its composition were used: chemical and physical irritation, partial removal of areas, as well as the development of conditioned reflexes and registration of biocurrents.

The associative zone connects the incoming sensory information with previously acquired knowledge. After processing, it generates a signal and transmits it to the motor zone. Thus, it is involved in remembering, thinking and learning new skills. Associative areas of the cerebral cortex are located in proximity to the corresponding sensory area.

The sensitive or sensory zone occupies 20% of the cerebral cortex. It also consists of several components:

somatosensory, located in the parietal zone is responsible for tactile and autonomic sensitivity;
visual;
auditory;
taste;
olfactory.

Impulses from the limbs and tactile organs on the left side of the body are sent along afferent pathways to the opposite lobe of the cerebral hemispheres for further processing.

The neurons of the motor zone are excited by impulses received from muscle cells and are located in the central gyrus of the frontal lobe. The input mechanism is similar to that of the sensory area, as the motor pathways form an overlap in the medulla oblongata and follow to the opposite motor area.

Crinkles furrows and fissures

The cerebral cortex is formed by several layers of neurons. A characteristic feature of this part of the brain is a large number of wrinkles or convolutions, due to which its area is many times greater than the surface area of the hemispheres.

Cortical architectonic fields determine the functional structure of sections of the cerebral cortex. All of them are different in morphological features and regulate different functions. Thus, 52 different fields are allocated, located in certain areas. According to Brodman, this division looks like this:

The central sulcus separates the frontal lobe from the parietal region, the precentral gyrus lies in front of it, and the posterior central gyrus lies behind it.
The lateral furrow separates the parietal zone from the occipital zone. If you spread its lateral edges, then inside you can see a hole, in the center of which there is an island.
The parieto-occipital sulcus separates the parietal lobe from the occipital lobe.

The core of the motor analyzer is located in the precentral gyrus, while the upper parts of the anterior central gyrus belong to the muscles of the lower limb, and the lower parts belong to the muscles of the oral cavity, pharynx and larynx.

The right-sided gyrus forms a connection with the motor apparatus of the left half of the body, the left-sided - with the right side.

The retrocentral gyrus of the 1st lobe of the hemisphere contains the core of the analyzer of tactile sensations and is also connected with the opposite part of the body.

Cell layers

The cerebral cortex performs its functions through the neurons located in its thickness. Moreover, the number of layers of these cells may differ depending on the site, the dimensions of which also vary in size and topography. Experts distinguish the following layers of the cerebral cortex:

The surface molecular layer is formed mainly from dendrites, with a small interspersed with neurons, the processes of which do not leave the layer boundary.
The outer granular consists of pyramidal and stellate neurons, the processes of which connect it with the next layer.
The pyramidal neuron is formed by pyramidal neurons, the axons of which are directed downward, where they break off or form associative fibers, and their dendrites connect this layer with the previous one.
The inner granular layer is formed by stellate and small pyramidal neurons, the dendrites of which go into the pyramidal layer, and its long fibers go into the upper layers or go down into the white matter of the brain.
Ganglionic consists of large pyramidal neurocytes, their axons extend beyond the cortex and connect various structures and departments of the central nervous system with each other.

The multiform layer is formed by all types of neurons, and their dendrites are oriented to the molecular layer, and the axons penetrate the previous layers or go beyond the cortex and form associative fibers that form a connection between gray matter cells and the rest of the functional centers of the brain.

Video: Cerebral cortex

Anatomy

The neocortex contains two main types of neurons: pyramidal neurons (~80% of neocortical neurons) and interneurons (~20% of neocortical neurons).

The structure of the neocortex is relatively homogeneous (hence the alternative name: "isocortex"). In humans, it has six horizontal layers of neurons that differ in the type and nature of connections. Vertically, neurons are combined into so-called cortex columns. In dolphins, the neocortex has 3 horizontal layers of neurons.

Principle of operation

A fundamentally new theory of the algorithms of the neocortex was developed in Menlo Park, California, USA (Silicon Valley), by Jeff Hawkins. The theory of hierarchical temporary memory has been implemented in software as a computer algorithm, which is available for use under a license from numenta.com.

The same algorithm processes all the senses.
The function of a neuron is based on memory over time, something like causal relationships that hierarchically develop into larger and larger objects from smaller ones.

Links

W. Mountcastle "Organizing Principle of Brain Function: Elementary Module and Distributed System"
Translation into Russian of the article "Hierarchical temporal memory" from Numenta.com

Wikimedia Foundation. 2010 .

See what "New bark" is in other dictionaries:

NEOCORTEX (NEW CORTEX)- Evolutionarily the newest and most complex of the nervous tissues. The frontal, parietal, temporal, and occipital lobes of the brain are made up of the neocortex... Explanatory Dictionary of Psychology

- (cortex hemispheria cerebri), pallium, or cloak, a layer of gray matter (1 5 mm) covering the cerebral hemispheres of mammals. This part of the brain, developed in the later stages of evolution, plays an extremely important role in ... ... Biological encyclopedic dictionary

Bark: Wiktionary has an entry for "bark" In Biology: Bark is the outer part of a tree trunk. The bark of large p ... Wikipedia

cortex- brain: the cortex (cerebral cortex) is the upper layer of the cerebral hemispheres, consisting primarily of nerve cells with a vertical orientation (pyramidal cells), as well as of afferent (centripetal) and efferent bundles ... ... Great Psychological Encyclopedia

A layer of gray matter 1 5 mm thick covering the cerebral hemispheres of mammals and humans. This part of the brain (See Brain), which developed in the later stages of the evolution of the animal world, plays exclusively ... ... Great Soviet Encyclopedia

The cerebrum (cortex cerebri, PNA, LNH; substantia corticalis, BNA, JNA; synonym: K. of the cerebral hemispheres, K. of the brain, mantle, cloak) is the surface layer of the cerebral hemispheres, formed by its gray matter; plays an important role in... Medical Encyclopedia

- (cortex cerebri) gray matter located on the surface of the cerebral hemispheres and consisting of nerve cells (neurons), neuroglia, interneuronal connections of the cortex, and blood vessels. K. b. m. contains central (cortical) sections ... ... Medical Encyclopedia

The cerebral cortex is a multilevel brain structure in humans and many mammals, consisting of gray matter and located in the peripheral space of the hemispheres (the gray matter of the cortex covers them). Structure controls important functions and processes in the brain and other internal organs.

(hemispheres) of the brain in the cranium occupy about 4/5 of the entire space. Their component is white matter, which includes long myelinated axons of nerve cells. From the outside, the hemispheres are covered by the cerebral cortex, which also consists of neurons, as well as glial cells and non-myelinated fibers.

It is customary to divide the surface of the hemispheres into some zones, each of which is responsible for performing certain functions in the body (for the most part, these are reflex and instinctive activities and reactions).

There is such a thing - "ancient bark". It is evolutionarily the most ancient cloak structure of the cerebral cortex in all mammals. They also distinguish the “new cortex”, which in lower mammals is only outlined, and in humans it forms most of the cerebral cortex (there is also an “old cortex”, which is newer than the “ancient”, but older than the “new”).

Functions of the cortex

The human cerebral cortex is responsible for controlling a variety of functions that are used in various aspects of the life of the human body. Its thickness is about 3-4 mm, and the volume is quite impressive due to the presence of channels connecting with the central nervous system. How perception, processing of information, decision-making takes place through the electrical network with the help of nerve cells with processes.

Inside the cerebral cortex, various electrical signals are produced (the type of which depends on the current state of the person). The activity of these electrical signals depends on the well-being of a person. Technically, electrical signals of this type are described using frequency and amplitude indicators. More connections and localized in places that are responsible for providing the most complex processes. At the same time, the cerebral cortex continues to actively develop throughout a person’s life (at least until the moment when his intellect develops).

In the process of processing information entering the brain, reactions (mental, behavioral, physiological, etc.) are formed in the cortex.

The most important functions of the cerebral cortex are:

The interaction of internal organs and systems with the environment, as well as with each other, the correct course of metabolic processes within the body.
High-quality reception and processing of information received from the outside, awareness of the information received due to the flow of thinking processes. High sensitivity to any received information is achieved due to the large number of nerve cells with processes.
Support for the continuous relationship between various organs, tissues, structures and systems of the body.
Formation and correct work of human consciousness, the flow of creative and intellectual thinking.
Implementation of control over the activity of the speech center and processes associated with various mental and emotional situations.
Interaction with the spinal cord and other systems and organs of the human body.

The cerebral cortex in its structure has the anterior (frontal) sections of the hemispheres, which are currently the least studied by modern science. These areas are known to be virtually immune to external influences. For example, if these departments are affected by external electrical impulses, they will not give any reaction.

Some scientists are sure that the anterior parts of the cerebral hemispheres are responsible for the self-awareness of a person, for his specific character traits. It is a known fact that people in whom the anterior sections are affected to one degree or another experience certain difficulties with socialization, they practically do not pay attention to their appearance, they are not interested in work activity, they are not interested in the opinions of others.

From the point of view of physiology, the importance of each department of the cerebral hemispheres is difficult to overestimate. Even those that are currently not fully understood.

Layers of the cerebral cortex

The cerebral cortex is formed by several layers, each of which has a unique structure and is responsible for performing certain functions. All of them interact with each other, performing a common job. It is customary to distinguish several main layers of the cortex:

Molecular. In this layer, a huge number of dendritic formations are formed, which are woven together in a chaotic manner. The neurites are oriented parallel, forming a layer of fibers. There are relatively few nerve cells here. It is believed that the main function of this layer is associative perception.
External. A lot of nerve cells with processes are concentrated here. Neurons vary in shape. Nothing is known exactly about the functions of this layer.
External pyramidal. Contains many nerve cells with processes that vary in size. Neurons are predominantly conical in shape. The dendrite is large.
Internal granular. Includes a small number of small neurons located at some distance. Between the nerve cells are fibrous grouped structures.
Internal pyramidal. Nerve cells with processes that enter it are large and medium in size. The upper part of the dendrites may be in contact with the molecular layer.
Cover. Includes spindle-shaped nerve cells. For neurons in this structure, it is characteristic that the lower part of the nerve cells with processes reaches up to the white matter.

The cerebral cortex includes various layers that differ in shape, location, and the functional component of their elements. In the layers there are neurons of pyramidal, spindle, stellar, branched types. Together they create more than fifty fields. Despite the fact that the fields do not have clearly defined boundaries, their interaction with each other makes it possible to regulate a huge number of processes associated with the receipt and processing of impulses (that is, incoming information), the creation of a response to the influence of stimuli.

The structure of the cortex is extremely complex and not fully understood, so scientists cannot say exactly how some elements of the brain work.

The level of a child's intellectual abilities is related to the size of the brain and the quality of blood circulation in the brain structures. Many children who had hidden birth injuries in the spinal region have a noticeably smaller cerebral cortex than their healthy peers.

prefrontal cortex

A large section of the cerebral cortex, which is presented in the form of anterior sections of the frontal lobes. With its help, control, management, focusing of any actions that a person performs are carried out. This department allows us to properly allocate our time. The well-known psychiatrist T. Goltieri described this site as a tool with which people set goals and develop plans. He was convinced that a properly functioning and well-developed prefrontal cortex is the most important factor in the effectiveness of an individual.

The main functions of the prefrontal cortex are also commonly referred to as:

Concentration of attention, focusing on obtaining only the information necessary for a person, ignoring outside thoughts and feelings.
The ability to "reboot" consciousness, directing it in the right thought direction.
Perseverance in the process of performing certain tasks, striving to obtain the intended result, despite the circumstances that arise.
Analysis of the current situation.
Critical thinking, which allows you to create a set of actions to search for verified and reliable data (checking the information received before using it).
Planning, development of certain measures and actions to achieve the goals.
Event forecasting.

Separately, the ability of this department to manage human emotions is noted. Here, the processes occurring in the limbic system are perceived and translated into specific emotions and feelings (joy, love, desire, grief, hatred, etc.).

Different structures of the cerebral cortex are assigned different functions. There is still no consensus on this issue. The international medical community is now coming to the conclusion that the cortex can be divided into several large zones, including cortical fields. Therefore, taking into account the functions of these zones, it is customary to distinguish three main departments.

Zone responsible for pulse processing

Impulses coming through the receptors of the tactile, olfactory, visual centers go exactly to this zone. Almost all reflexes associated with motor skills are provided by pyramidal neurons.

Here is the department that is responsible for receiving impulses and information from the muscular system, actively interacts with different layers of the cortex. It receives and processes all the impulses that come from the muscles.

If for some reason the head cortex is damaged in this area, then the person will experience problems with the functioning of the sensory system, problems with motor skills and the work of other systems that are associated with sensory centers. Outwardly, such violations will manifest themselves in the form of constant involuntary movements, convulsions (of varying severity), partial or complete paralysis (in severe cases).

Sensory area

This area is responsible for processing electrical signals to the brain. Several departments are located here at once, which ensure the susceptibility of the human brain to impulses coming from other organs and systems.

Occipital (processes impulses coming from the visual center).
Temporal (carries out the processing of information coming from the speech and auditory center).
Hippocampus (analyzes impulses from the olfactory center).
Parietal (processes data received from taste buds).

In the zone of sensory perception, there are departments that also receive and process tactile signals. The more neural connections there are in each department, the higher will be its sensory ability to receive and process information.

The departments noted above occupy about 20-25% of the entire cerebral cortex. If the area of sensory perception is somehow damaged, then a person may have problems with hearing, vision, smell, and touch. The received pulses will either not reach, or will be processed incorrectly.

Violations of the sensory zone will not always lead to the loss of some kind of feeling. For example, if the auditory center is damaged, this will not always lead to complete deafness. However, a person will almost certainly have certain difficulties with the correct perception of the received sound information.

association zone

In the structure of the cerebral cortex there is also an associative zone, which provides contact between the signals of the neurons of the sensory zone and the motor center, and also gives the necessary feedback signals to these centers. The associative zone forms behavioral reflexes, takes part in the processes of their actual implementation. It occupies a significant (comparatively) part of the cerebral cortex, covering the departments included in both the frontal and posterior parts of the cerebral hemispheres (occipital, parietal, temporal).

The human brain is designed in such a way that in terms of associative perception, the posterior parts of the cerebral hemispheres are especially well developed (development occurs throughout life). They control speech (its understanding and reproduction).

If the anterior or posterior sections of the association zone are damaged, then this can lead to certain problems. For example, in case of damage to the departments listed above, a person will lose the ability to correctly analyze the information received, will not be able to give the simplest forecasts for the future, start from the facts in the processes of thinking, use the experience gained earlier, deposited in memory. There may also be problems with orientation in space, abstract thinking.

The cerebral cortex acts as a higher integrator of impulses, while emotions are concentrated in the subcortical zone (hypothalamus and other departments).

Different areas of the cerebral cortex are responsible for performing certain functions. There are several methods to consider and determine the difference: neuroimaging, comparison of electrical activity patterns, studying the cellular structure, etc.

At the beginning of the 20th century, K. Brodmann (a German researcher in the anatomy of the human brain) created a special classification, dividing the cortex into 51 sections, basing his work on the cytoarchitectonics of nerve cells. Throughout the 20th century, the fields described by Brodmann were discussed, refined, renamed, but they are still used to describe the cerebral cortex in humans and large mammals.

Many Brodmann fields were initially determined on the basis of the organization of neurons in them, but later their boundaries were refined in accordance with the correlation with different functions of the cerebral cortex. For example, the first, second, and third fields are defined as the primary somatosensory cortex, the fourth field is the primary motor cortex, and the seventeenth field is the primary visual cortex.

At the same time, some Brodmann fields (for example, area 25 of the brain, as well as fields 12-16, 26, 27, 29-31 and many others) have not been fully studied.

Speech motor zone

A well-studied area of the cerebral cortex, which is also called the center of speech. The zone is conditionally divided into three major departments:

Broca's speech motor center. Forms a person's ability to speak. It is located in the posterior gyrus of the anterior part of the cerebral hemispheres. Broca's center and the motor center of speech motor muscles are different structures. For example, if the motor center is damaged in some way, then the person will not lose the ability to speak, the semantic component of his speech will not suffer, but the speech will cease to be clear, and the voice will become slightly modulated (in other words, the quality of pronunciation of sounds will be lost). If Broca's center is damaged, then the person will not be able to speak (just like a baby in the first months of life). Such disorders are called motor aphasia.
Wernicke's sensory center. It is located in the temporal region, is responsible for the functions of receiving and processing oral speech. If Wernicke's center is damaged, then sensory aphasia is formed - the patient will not be able to understand the speech addressed to him (and not only from another person, but also his own). The uttered by the patient will be a set of incoherent sounds. If there is a simultaneous defeat of the centers of Wernicke and Broca (usually this occurs with a stroke), then in these cases the development of motor and sensory aphasia is observed at the same time.
Center for the perception of written speech. It is located in the visual part of the cerebral cortex (field No. 18 according to Brodman). If it turns out to be damaged, then the person has agraphia - the loss of the ability to write.

Thickness

All mammals that have relatively large brain sizes (in general terms, not compared to body size) have a fairly thick cerebral cortex. For example, in field mice, its thickness is about 0.5 mm, and in humans - about 2.5 mm. Scientists also identify a certain dependence of the thickness of the bark on the weight of the animal.

With the help of modern examinations (especially through MRI), it is possible to accurately measure the thickness of the cerebral cortex in any mammal. At the same time, it will vary significantly in different areas of the head. It is noted that in sensory areas the cortex is much thinner than in motor (motor).

Studies show that the thickness of the cerebral cortex largely depends on the level of development of human intelligence. The smarter the individual, the thicker the cortex. Also, a thick cortex is recorded in people who constantly and for a long time suffer from migraine pains.

Furrows, folds, fissures

Among the features of the structure and functions of the cerebral cortex, it is also customary to distinguish cracks, furrows and convolutions. These elements form a large surface area of the brain in mammals and humans. If you look at the human brain in a section, you can see that more than 2/3 of the surface is hidden in the grooves. Fissures and furrows are depressions in the cortex that differ only in size:

The fissure is a large groove that divides the mammalian brain into parts, into two hemispheres (longitudinal medial fissure).
A sulcus is a shallow depression surrounding the gyri.

At the same time, many scientists consider such a division into furrows and crevices to be very arbitrary. This is largely due to the fact that, for example, the lateral sulcus is often referred to as the "lateral fissure" and the central sulcus as the "central fissure".

The blood supply to the parts of the cerebral cortex is carried out with the help of two arterial pools at once, which form the vertebral and internal carotid arteries.

The most sensitive area of the cerebral hemispheres is the central posterior gyrus, which is associated with the innervation of different parts of the body.

NEOCORTEX NEOCORTEX

(from neo... and lat. cortex- bark, shell), new bark, neo-pallium, osn. part of the cerebral cortex. N. carries out the highest level of coordination of work of a brain and formation of difficult forms of behavior. In the process of evolution, N. first appears in reptiles, in which it is small in size and relatively simple in structure (the so-called lateral cortex). N. receives a typical multilayer structure only in mammals, in which it consists of 6-7 layers of cells (pyramidal, stellate, fusiform) and is divided into lobes: frontal, parietal, temporal, occipital, and mediobasal. In turn, the lobes are subdivided into areas, subareas and fields that differ in their cellular structure and connections with the deep parts of the brain. Along with projection (vertical) fibers N.'s neurons form associative (horizontal) fibers, to-rye at mammals and especially at the person are collected in anatomically expressed bunches (eg, an occipital and frontal bunch) providing the simultaneous coordinated activity decomp. zones N. As a part of N. allocate naib, difficultly constructed associative bark, edges in the course of evolution experiences the greatest increase whereas primary sensory fields N. relatively decrease. (see. BARKETS OF THE BRAIN).

.(Source: "Biological Encyclopedic Dictionary." Chief editor M. S. Gilyarov; Editorial board: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected . - M .: Sov. Encyclopedia, 1986.)

See what "NEOCORTEX" is in other dictionaries:

Neocortex ...

New cortex (synonyms: neocortex, isocortex) (lat. neocortex) new areas of the cerebral cortex, which in lower mammals are only outlined, and in humans they make up the main part of the cortex. The new bark is located in the upper layer of the hemispheres ... ... Wikipedia

neocortex- 3.1.15 neocortex: The new cerebral cortex, which ensures the implementation of intellectual mental activity by human thinking. 3.1.16 Source... Dictionary-reference book of terms of normative and technical documentation

- (neocortex; neo + lat. cortex bark) see Bark new ... Big Medical Dictionary

neocortex- at, h. Evolutionary novelty and complexity of nerve tissue, from which the frontal, tim yan, skronev and potilichny parts of the brain are formed ... Ukrainian glossy dictionary

Archi, paleo, neocortex... Spelling Dictionary

The term cortex refers to any outer layer of brain cells. The mammalian brain has three types of cortex: pear-shaped cortex (pyriform cortex), which has olfactory functions; the old bark (archicortex), which is the main part. Part… … Psychological Encyclopedia