Functional areas of the cerebral cortex. Motor areas of the cortex

Reading functions are provided by the lexical center (the center of the lexicon). The center of the lexia is located in the angular gyrus.

Graphic analyzer, graphic center, writing function

Writing functions are provided by the graphic center (graphic center). The center of the graph is located in the posterior part of the middle frontal gyrus.

Counting Analyzer, Calculation Center, Counting Function

The functions of the account are provided by the counting center (calculation center). The center of calculation is located at the junction of the parieto-occipital region.

Praxis, praxis analyzer, praxis center

Praxis is the ability to perform purposeful motor acts. Praxis is formed in the process of human life, starting from infancy, and is provided by a complex functional system of the brain with the participation of the cortical fields of the parietal lobe (lower parietal lobule) and the frontal lobe, especially the left hemisphere in right-handed people. For normal praxis, the preservation of the kinesthetic and kinetic basis of movements, visual-spatial orientation, programming processes and control of purposeful actions are necessary. The defeat of the praxic system at one level or another is manifested by such a type of pathology as apraxia. The term "praxis" comes from the Greek word "praxis" which means "action". - this is a violation of a purposeful action in the absence of muscle paralysis and the preservation of its constituent elementary movements.

Gnostic center, center of gnosis

In the right hemisphere of the brain in right-handers, in the left hemisphere of the brain in left-handers, many gnostic functions are represented. With damage to the predominantly right parietal lobe, anosognosia, autopagnosia, and constructive apraxia may occur. The center of gnosis is also associated with ear for music, orientation in space, and the center of laughter.

memory, thinking

The most complex cortical functions are memory and thinking. These functions do not have a clear localization.

Memory, memory function

Various sections are involved in the implementation of the memory function. The frontal lobes provide active purposeful mnestic activity. The posterior gnostic sections of the cortex are associated with particular forms of memory - visual, auditory, tactile-kinesthetic. The speech zones of the cortex carry out the process of encoding incoming information into verbal logical-grammatical systems and verbal systems. The mediobasal regions of the temporal lobe, in particular the hippocampus, translate current impressions into long-term memory. The reticular formation ensures the optimal tone of the cortex, charging it with energy.

Thinking, the function of thinking

The function of thinking is the result of the integrative activity of the entire brain, especially the frontal lobes, which are involved in organizing the purposeful conscious activity of a person, man, woman. Programming, regulation and control take place. At the same time, in right-handers, the left hemisphere is the basis of predominantly abstract verbal thinking, and the right hemisphere is mainly associated with concrete figurative thinking.

The development of cortical functions begins in the first months of a child's life and reaches its perfection by the age of 20.

In subsequent articles, we will focus on topical issues of neurology: areas of the cerebral cortex, areas of the cerebral hemispheres, visual, area of the cortex, auditory area of the cortex, motor motor and sensitive sensory areas, associative, projection areas, motor and functional areas, speech areas, primary areas cerebral cortex, associative, functional zones, frontal cortex, somatosensory zone, cortical tumor, absence of the cortex, localization of higher mental functions, problem of localization, cerebral localization, concept of dynamic localization of functions, research methods, diagnostics.

Cortex treatment

Sarclinic uses proprietary methods for restoring the work of the cerebral cortex. Treatment of the cerebral cortex in Russia in adults, adolescents, children, treatment of the cerebral cortex in Saratov in boys and girls, boys and girls, men and women allows you to restore lost functions. In children, the development of the cerebral cortex, the centers of the brain, is activated. In adults and children, atrophy and subatrophy of the cerebral cortex, cortical disturbance, inhibition in the cortex, excitation in the cortex, damage to the cortex, changes in the cortex, sore cortex, vasoconstriction, poor blood supply, irritation and dysfunction of the cortex, organic damage, stroke, detachment , damage, diffuse changes, diffuse irritation, death, underdevelopment, destruction, disease, question to the doctor If the cerebral cortex has suffered, then with proper and adequate treatment it is possible to restore its functions.

. There are contraindications. Specialist consultation is required.

Text: ® SARCLINIC | Sarclinic.com \ Sarlinic.ru Photo: MedusArt / Photobank Photogenica / photogenica.ru The people shown in the photo are models, do not suffer from the described diseases and / or all coincidences are excluded.

The human is a surface layer that covers the cerebral hemisphere and is mainly formed by vertically oriented nerve cells (the so-called neurons), as well as their processes and efferent (centrifugal), afferent bundles (centripetal) and nerve fibers.

In addition, the basis of the composition of the cortex, in addition, includes cells, as well as neuroglia.

A very significant feature of the structure is the horizontal dense layering, which is primarily due to the whole ordered arrangement of each body of nerve cells and fibers. There are 6 main layers, which mainly differ in their own width, the overall density of its location, the size and shape of all the constituent external neurons.

Predominantly, precisely because of the vertical orientation of their processes, these bundles of all the various nerve fibers, as well as the bodies of neurons, which have a vertical striation. And for the full-fledged functional organization of the human cerebral cortex, the column-like, vertical location of absolutely all internal nerve cells on the surface of the cerebral cortex zone is of great importance here.

The main type of all the main nerve cells that are part of the cerebral cortex are special pyramidal cells. The body of these cells resembles an ordinary cone, from the height of which one long and thick, apical dendrite begins to depart. An axon and shorter basal dendrites also depart from the base of the body of this pyramidal cell, heading into a full-fledged white matter, which is located directly under the cerebral cortex, or branching in the cortex.

All the dendrites of the cells of the pyramid carry a fairly large number of spines, outgrowths, which take the most active part in the full formation of synaptic contacts at the end of afferent fibers that come to the cerebral cortex from other subcortical formations and sections of the cortex. The axons of these cells are able to form efferent main pathways that go directly from the C.G.M. The sizes of all pyramidal cells can vary from 5 to 150 microns (150 are giant cells named after Betz). In addition to pyramidal neurons, K.G.M. the composition includes some spindle-shaped and stellate types of interneurons that are involved in receiving incoming afferent signals, as well as the formation of interneuronal functional connections.

Features of the cerebral cortex

Based on various phylogenesis data, the cerebral cortex is divided into ancient (paleocortex), old (archicortex), and new (neocortex). In the phylogeny of K.G.M. there is a relative ubiquitous increase in the territory of the new surface of the crust, with a slight decrease in the area of the old and ancient.

Functionally, the areas of the cerebral cortex are divided into 3 types: associative, motor and sensory. In addition, the cerebral cortex is also responsible for the corresponding areas.

What is the cerebral cortex responsible for?

In addition, it is important to note that the entire cerebral cortex, in addition to all of the above, is responsible for everything. As part of the zones of the cerebral cortex, these are neurons of various structures, including stellate, small and large pyramidal, basket, fusiform and others. In a functional relationship, all main neurons are divided into the following types:

Intercalary neurons (fusiform, small pyramidal and others). Interneurons also have subdivisions and can be both inhibitory and excitatory (small and large basket neurons, neurons with cystic neurons and candelabra-shaped axons)
Afferent (these are the so-called stellate cells) - which receive impulses from all specific pathways, as well as various specific sensations. It is these cells that transmit impulses directly to the efferent and intercalary neurons. Groups of polysensory neurons, respectively, receive different impulses from the optic tubercles of the associative nuclei
Efferent neurons (they are called large pyramidal cells) - impulses from these cells go to the so-called periphery, where they provide a certain type of activity

Neurons, as well as processes on the surface of the cerebral cortex, are also arranged in six layers. Neurons that perform the same reflex functions are located strictly one above the other. Thus, individual columns are considered to be the main structural unit of the surface of the cerebral cortex. And the most pronounced connection between the third, fourth and fifth stage of the layers of K.G.M.

Pads of the cerebral cortex

The following factors can also be considered proof of the presence of columns in the cerebral cortex:
With the introduction of various microelectrodes into the K.G.M. an impulse is recorded (recorded) strictly perpendicularly under the full impact of a similar reflex reaction. And when the electrodes are inserted in a strictly horizontal direction, characteristic impulses are recorded for a variety of reflex reactions. Basically, the diameter of one column is 500 µm. All adjacent columns are tightly connected in all functional respects, and are also often located with each other in close reciprocal relationships (some inhibit, others excite).

When stimuli act on the response, many columns are also involved and a perfect synthesis and analysis of stimuli occurs - this is the screening principle.

Since the cerebral cortex grows in the periphery, then all the superficial layers of the cerebral cortex are fully related to all signal systems. These superficial layers consist of a very large number of nerve cells (about 15 billion) and, together with their processes, with the help of which the possibility of such unlimited closing functions, wide associations is created - this is the essence of all the activity of the signaling second system. But with all this, the second s.s. works with other systems.

Attention!

The cerebral cortex is the outer layer of the nervous tissue of the brain of humans and other mammalian species. The cerebral cortex is divided by a longitudinal fissure (lat. Fissura longitudinalis) into two large parts, which are called the cerebral hemispheres or hemispheres - right and left. Both hemispheres are connected from below by the corpus callosum (lat. Corpus callosum). The cerebral cortex plays a key role in the performance of brain functions such as memory, attention, perception, thinking, speech, and consciousness.

In large mammals, the cerebral cortex is collected in the mesentery, giving a large area of its surface in the same volume of the skull. The ripples are called convolutions, and between them lie furrows and deeper cracks.

Two-thirds of the human brain is hidden in furrows and crevices.

The cerebral cortex is 2 to 4 mm thick.

The cortex is formed by gray matter, which consists mainly of cell bodies, mainly astrocytes, and capillaries. Therefore, even visually, the tissue of the cortex differs from the white matter, which lies deeper and consists mainly of white myelin fibers - axons of neurons.

The outer part of the cortex, the so-called neocortex (lat. Neocortex), the most evolutionarily young part of the cortex in mammals, has up to six cell layers. Neurons from different layers are interconnected in cortical minicolumns. Different areas of the cortex, known as Brodmann's fields, differ in cytoarchitectonics (histological structure) and functional role in sensitivity, thinking, consciousness and cognition.

Development

The cerebral cortex develops from the embryonic ectoderm, namely from the anterior part of the neural plate. The neural plate folds and forms the neural tube. From the cavity inside the neural tube, the ventricular system arises, and from the epithelial cells of its walls - neurons and glia. From the frontal part of the neural plate, the forebrain, the cerebral hemispheres, and then the cortex are formed.

The zone of growth of cortical neurons, the so-called "S" zone, is located next to the ventricular system of the brain. This zone contains progenitor cells, which later in the process of differentiation become glial cells and neurons. Glial fibers formed in the first divisions of progenitor cells, radially oriented, cover the thickness of the cortex from the ventricular zone to the pia mater (lat. Pia mater) and form "rails" for the migration of neurons outward from the ventricular zone. These daughter nerve cells become the pyramidal cells of the cortex. The process of development is clearly regulated in time and guided by hundreds of genes and mechanisms of energy regulation. In the process of development, a layered structure of the cortex is also formed.

Development of the cortex between 26 and 39 weeks (human embryo)

Cell layers

Each of the cell layers has a characteristic density of nerve cells and connections with other areas. There are direct connections between different parts of the cortex and indirect connections, for example, through the thalamus. One typical pattern of cortical dissection is Gennari's streak in the primary visual cortex. This strand is visually whiter than tissue, visible to the naked eye at the base of the spur groove (lat. Sulcus calcarinus) in the occipital lobe (lat. Lobus occipitalis). The streak of Gennari is made up of axons that carry visual information from the thalamus to the fourth layer of the visual cortex.

Staining of cell columns and their axons allowed neuroanatomists at the beginning of the 20th century. to make a detailed description of the layered structure of the bark in different species. After the work of Korbinian Brodmann (1909), the neurons in the cortex were grouped into six main layers - from the outer, adjacent to the pia mater; to internal bordering white matter:

Layer I, the molecular layer, contains several scattered neurons and consists predominantly of vertically (apically) oriented pyramidal neurons and horizontally oriented axons, and glial cells. During development, this layer contains Cajal-Retzius cells and subpial cells (cells located just below the (pia mater) granular layer. Spiny astrocytes are also sometimes found here. Apical dendritic bundles are considered to be of great importance for reciprocal connections ("feedback") in the cerebral cortex, and are involved in the performance of the functions of associative learning and attention.
Layer II, the outer granular layer, contains small pyramidal neurons and numerous stellate neurons (whose dendrites emerge from different sides of the cell body, forming a star shape).
Layer III, the outer pyramidal layer, contains predominantly small to medium pyramidal and non-pyramidal neurons with vertically oriented intracortical (those within the cortex). Cell layers from I to III are the main targets of intraspinal afferents, and layer III is the main source of cortico-cortical connections.
Layer IV, the inner granular layer, contains various types of pyramidal and stellate neurons and serves as the main target for thalamocortical (thalamus to cortex) afferent fibers.
Layer V, the inner pyramidal layer, contains large pyramidal neurons whose axons leave the measles and travel to subcortical structures (such as the basal ganglia. In the primary motor cortex, this layer contains Betz cells whose axons travel through the internal capsule, brainstem, and spinal cord and form a corticospinal pathway that controls voluntary movements.
Layer VI, the polymorphic or multiform layer, contains few pyramidal neurons and many polymorphic neurons; efferent fibers from this layer go to the thalamus, establishing a reverse (reciprocal) connection between the thalamus and the cortex.

The outer surface of the brain, on which the areas are marked, is supplied with blood by the cerebral arteries. The site marked in blue corresponds to the anterior cerebral artery. The section of the posterior cerebral artery is marked in yellow

The cortical layers are not just stacked one on one. There are characteristic connections between different layers and cell types in them, which permeate the entire thickness of the cortex. The basic functional unit of the cortex is considered to be a cortical minicolumn (a vertical column of neurons in the cerebral cortex that passes through its layers. Minicolumns include from 80 to 120 neurons in all areas of the brain, except for the primary visual cortex of primates).

Areas of the cortex without a fourth (inner granular) layer are called agranular, with a rudimentary granular layer - dysgranular. The speed of information processing within each layer is different. So in II and III - slow, with a frequency (2 Hz), while in the frequency of oscillations in layer V is much faster - 10-15 Hz.

Cortical zones

Anatomically, the cortex can be divided into four parts, which have names corresponding to the names of the bones of the skull that cover:

Frontal lobe (brain), (lat. Lobus frontalis)
Temporal lobe, (lat. Lobus temporalis)
Parietal lobe, (lat. Lobus parietalis)
Occipital lobe, (lat. Lobus occipitalis)

Given the features of the laminar (layered) structure, the cortex is divided into neocortex and alocortex:

Neocortex (lat. Neocortex, other names - isocortex, lat. Isocortex and neopallium, lat. Neopallium) - part of the mature cerebral cortex with six cell layers. An example of a neocortical region is Brodmann's area 4, also known as the primary motor cortex, primary visual cortex, or Brodmann's area 17. The neocortex is divided into two types: the isocortex (the actual neocortex, samples of which, Brodmann's areas 24,25 and 32 have only been considered) and prosocortex, which is represented, in particular, by Brodmann's field 24, Brodmann's field 25 and Brodmann's field 32
Alocortex (lat. Allocortex) - a part of the cortex with less than six cell layers, also divided into two parts: paleocortex (lat. Paleocortex) with a three-layer, archicortex (lat. Archicortex) of four to five, and the perialocortex adjacent to them (lat. piallocortex). Examples of areas with such a layered structure are the olfactory cortex: vaulted gyrus (lat. Gyrus fornicatus) with a hook (lat. Uncus), hippocampus (lat. Hippocampus) and structures close to it.

There is also a “transitional” (between the alocortex and neocortex) cortex, which is called paralimbic, where cell layers 2,3 and 4 merge. This zone contains the prosocortex (from the neocortex) and the perialocortex (from the alocortex).

Cortex. (according to Poirier fr. Poirier.). Livooruch - groups of cells, on the right - fibers.

Brodmann fields

Different parts of the cortex are involved in different functions. You can see and fix this difference in various ways - by visually affecting certain areas, comparing patterns of electrical activity, using neuroimaging techniques, studying the cellular structure. Based on these differences, researchers classify areas of the cortex.

The most famous and cited for a century is the classification, which was created in 1905-1909 by the German researcher Korbinian Brodmann. He divided the cerebral cortex into 51 regions based on the cytoarchitectonics of neurons, which he studied in the cerebral cortex using Nissl cell staining. Brodman published his maps of cortical areas in humans, monkeys, and other species in 1909.

The Brodmann fields have been actively and extensively discussed, discussed, refined, and renamed for almost a century and remain the most widely known and often cited structures of the cytoarchitectonic organization of the human cerebral cortex.

Many of the Brodmann fields, originally defined solely by their neuronal organization, were later associated according to correlation with various cortical functions. For example, Fields 3, 1 & 2 are the primary somatosensory cortex; field 4 is the primary motor cortex; field 17 is primary to the visual cortex, and fields 41 and 42 are more correlated with the primary auditory cortex. Determination of the correspondence of the processes of Higher nervous activity to areas of the cerebral cortex and binding to specific Brodmann fields is carried out using neurophysiological studies, functional magnetic resonance imaging and other methods (as it was, for example, done with the binding of Broca's zones of speech and language in Brodmann fields 44 and 45). However, with the help of functional imaging, it is only possible to approximately determine the localization of the activation of brain processes in the Brodmann fields. And to accurately determine their boundaries in each individual brain, a histological study is needed.

Some of the important Brodmann fields. Where: Primary somatosensory cortex - primary somatosensory cortex Primary motor cortex - primary motor (motor) cortex; Wernicke's area - Wernicke's area; Primary visual area - primary visual area; Primary auditory cortex - primary auditory cortex; Broca's area - Broca's area.

bark thickness

In mammalian species with large brain sizes (in absolute terms, not just relative to body size), the cortex tends to be thicker in measles. The range, however, is not very large. Small mammals such as shrews have a neocortex about 0.5 mm thick; and species with the largest brains, such as humans and cetaceans, are 2.3–2.8 mm thick. There is an approximately logarithmic relationship between brain weight and cortical thickness.

Magnetic resonance imaging (MRI) of the brain makes possible intravital measurements of the thickness of the cortex and the alignment with respect to body size. The thickness of different areas is variable, but in general, sensory (sensitive) areas of the cortex are thinner than motor (motor). One of the studies shows the dependence of the thickness of the cortex on the level of intelligence. Another study showed greater cortical thickness in migraine sufferers. However, other studies show no such relationship.

Convolutions, furrows and fissures

Together, these three elements - convolutions, furrows and fissures - create a large surface area of the brain of humans and other mammals. When looking at the human brain, it is noticeable that two-thirds of the surface is hidden in the grooves. Both furrows and fissures are depressions in the cortex, but they vary in size. The sulcus is a shallow groove that surrounds the gyri. The fissure is a large groove that divides the brain into parts, as well as into two hemispheres, such as the medial longitudinal fissure. However, this distinction is not always clear-cut. For example, the lateral sulcus is also known as the lateral fissure and as the "Sylvian sulcus" and the "central sulcus", also known as the Central fissure and as the "Roland's sulcus".

This is very important in conditions where the size of the brain is limited by the internal size of the skull. An increase in the surface of the cerebral cortex with the help of a system of convolutions and furrows increases the number of cells that are involved in the performance of brain functions such as memory, attention, perception, thinking, speech, and consciousness.

blood supply

The supply of arterial blood to the brain and cortex, in particular, occurs through two arterial pools - the internal carotid and vertebral arteries. The terminal section of the internal carotid artery branches into branches - the anterior cerebral and middle cerebral arteries. In the lower (basal) parts of the brain, the arteries form the circle of Willis, due to which the arterial blood is redistributed between the arterial basins.

Middle cerebral artery

The middle cerebral artery (lat. A. Cerebri media) is the largest branch of the internal carotid artery. Violation of blood circulation in it can lead to the development of ischemic stroke and middle cerebral artery syndrome with the following symptoms:

Paralysis, plegia, or paresis of opposing muscles of the face and arm
Loss of sensory sensation opposing muscles of the face and arm
Damage to the dominant hemisphere (often the left) of the brain and the development of Broca's aphasia or Wernicke's aphasia
Damage to the non-dominant hemisphere (often the right) of the brain leads to unilateral spatial agnosia from the remote side of the lesion
Heart attacks in the zone of the middle cerebral artery lead to déviation conjuguée, when the pupils of the eyes move towards the side of the brain lesion.

Anterior cerebral artery

The anterior cerebral artery is a smaller branch of the internal carotid artery. Having reached the medial surface of the cerebral hemispheres, the anterior cerebral artery goes to the occipital lobe. It supplies the medial parts of the hemispheres to the level of the parietal-occipital sulcus, the area of the superior frontal gyrus, the area of the parietal lobe, and also the areas of the lower medial parts of the orbital gyri. Symptoms of her defeat:

Paresis of the leg or hemiparesis with a primary lesion of the leg on the opposite side.
Blockage of the paracentral branches leads to monoparesis of the foot, resembling peripheral paresis. Urinary retention or incontinence may occur. There are reflexes of oral automatism and grasping phenomena, pathological foot bending reflexes: Rossolimo, Bekhterev, Zhukovsky. There are changes in the mental state due to damage to the frontal lobe: decreased criticism, memory, unmotivated behavior.

Posterior cerebral artery

A steam vessel that supplies blood to the posterior parts of the brain (occipital lobe). Has an anastomosis with the middle cerebral artery. Its lesions lead to:

Homonymous (or upper quadrant) hemianopia (loss of part of the visual field)
Metamorphopsia (violation of visual perception of the size or shape of objects and space) and visual agnosia,
Alexia,
sensory aphasia,
Transient (transient) amnesia;
tubular vision,
Cortical blindness (while maintaining a reaction to light),
prosopagnosia,
Disorientation in space
Loss of topographic memory
Acquired achromatopsia - color vision deficiency
Korsakov's syndrome (violation of working memory)
Emotionally - affective disorders

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 deep 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 the central department of the 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.

Surface molecular, in which there are not very many nerve cells. Their processes are located in himself, and they do not go beyond.
The outer granular is formed from pyramidal and stellate neurocytes. The processes leave this layer and go to the next ones.
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.
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.
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.
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.

When studying localized areas and their functional characteristics, scientists used a variety of methods: chemical or physical stimulation, 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 from the right side - by the 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 of the motor function of the 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 damage to these areas leads not only to elementary movement disorders (paralysis, paresis, tremors), but also to disturbances in voluntary 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 computer science.

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.

The brain is the main human organ that controls all its vital functions, determines its personality, behavior and consciousness. Its structure is extremely complex and is a combination of billions of neurons grouped into departments, each of which performs its own function. Many years of research have made it possible to learn a lot about this organ.

What parts does the brain consist of?

The human brain is made up of several sections. Each of them performs its function, ensuring the vital activity of the body.

According to the structure, the brain is divided into 5 main sections.

Among them:

Oblong. This part is a continuation of the spinal cord. It consists of nuclei of gray matter and paths from white. It is this part that determines the connection between the brain and the body.
Average. It consists of 4 tubercles, two of which are responsible for vision and two for hearing.
Rear. The hindbrain includes the pons and cerebellum. This is a small department in the back of the head, which weighs within 140 grams. Consists of two hemispheres fastened together.
Intermediate. Consists of thalamus, hypothalamus.
Finite. This section forms both hemispheres of the brain, connected by the corpus callosum. The surface is full of convolutions and furrows covered by the cerebral cortex. The hemispheres are divided into lobes: frontal, parietal, temporal and occipital.

The last section occupies more than 80% of the total mass of the organ. Also, the brain can be divided into 3 parts: the cerebellum, the trunk and the cerebral hemispheres.

In this case, the entire brain has a coating in the form of a shell, divided into three components:

Cobweb (cerebrospinal fluid circulates through it)
Soft (adjacent to the brain and full of blood vessels)
Hard (contacts the skull and protects the brain from damage)

All components of the brain are important in the regulation of life and have a specific function. But the activity regulation centers are located in the cerebral cortex.

The human brain consists of many departments, each of which has a complex structure and performs a specific role. The largest of them is the final one, which consists of the cerebral hemispheres. All this is covered with three shells that provide protective and nourishing functions.

Learn about the structure and functions of the brain from the proposed video.

What functions does it perform?

The brain and its cortex perform a number of important functions.

Brain

It is difficult to list all the functions of the brain, because it is an extremely complex organ. This includes all aspects of the life of the human body. However, it is possible to single out the main functions performed by the brain.

The functions of the brain include all the feelings of a person. These are sight, hearing, taste, smell and touch. All of them are performed in the cerebral cortex. It is also responsible for many other aspects of life, including motor function.

In addition, diseases can occur against the background of external infections. The same meningitis that occurs due to infections of pneumococcus, meningococcus and the like. The development of the disease is characterized by pain in the head, fever, pain in the eyes and many other symptoms such as weakness, nausea and drowsiness.

Many diseases that develop in the brain and its cortex have not yet been studied. Therefore, their treatment is hampered by a lack of information. So it is recommended to consult a doctor at the first non-standard symptoms, which will prevent the disease by diagnosing it at an early stage.