New bark. The role of the neocortex in perception and thinking. 5interactions with the neocortex

In this article, we'll talk about the limbic system, the neocortex, their history, and main functions.

Limbic system

The limbic system of the brain is a collection of complex neuroregulatory structures in the brain. This system is not limited to just a few functions - it performs a huge number of tasks that are most important for a person. The purpose of the limbus is the regulation of higher mental functions and special processes of higher nervous activity, ranging from simple charm and wakefulness to cultural emotions, memory and sleep.

History of origin

The limbic system of the brain was formed long before the neocortex began to form. This oldest the hormonal-instinctive structure of the brain, which is responsible for the survival of the subject. Over a long evolution, you can form 3 main goals of the system for survival:

Dominance is a manifestation of superiority in a variety of ways
Food - Subject's food
Reproduction - transferring your genome to the next generation

Because man has animal roots, the limbic system is present in the human brain. Initially, Homo sapiens possessed only affects that affect the physiological state of the body. Over time, communication was formed by the type of shouting (vocalization). Individuals who knew how to convey their state with the help of emotions survived. Over time, the emotional perception of reality was more and more formed. Such evolutionary layering allowed people to unite into groups, groups into tribes, tribes into settlement, and the latter into whole nations. For the first time, the limbic system was discovered by the American researcher Paul McLean back in 1952.

System structure

Anatomically, the limbus includes areas of the paleocortex (ancient cortex), archicortex (old cortex), part of the neocortex ( new bark) and some structures of the subcortex (caudate nucleus, amygdala, pallidum). The listed names of various types of the crust indicate their formation at the specified time of evolution.

Weight specialists in the field of neuroscience, they dealt with the question of which structures belong to the limbic system. The latter includes many structures:

In addition, the system is closely related to the reticular formation system (the structure responsible for brain activation and wakefulness). The outline of the anatomy of the limbic complex rests on the gradual layering of one part on top of another. So, the cingulate gyrus lies on top, and then downward:

corpus callosum;
arch;
mamillary body;
amygdala;
hippocampus.

A distinctive feature of the visceral brain is its rich connection with other structures, consisting of complex pathways and two-way connections. Such a branched system of branches forms a complex of closed circles, which creates conditions for a prolonged circulation of excitement in the limbus.

Functional limbic system

The visceral brain actively receives and processes information from the outside world. What is the limbic system responsible for? Limbus- one of those structures that works in real time, allowing the body to effectively adapt to the conditions of the external environment.

The human limbic system in the brain performs the following function:

Formation of emotions, feelings and experiences. Through the prism of emotions, a person subjectively evaluates objects and the phenomenon of the environment.
Memory. This function is carried out by the hippocampus, which is located in the structure of the limbic system. Mnestic processes are provided by reverberation processes - circular motion excitations in the closed neural circuits of the sea horse.
Selection and correction of a model of suitable behavior.
Learning, retraining, fear and aggression;
Developing spatial skills.
Defensive and foraging behavior.
Expressiveness of speech.
Acquisition and maintenance of various phobias.
The work of the olfactory system.
Reaction of caution, preparation for action.
Regulation of sexual and social behavior. There is a concept of emotional intelligence - the ability to recognize the emotions of people around you.

At expressing emotions there is a reaction that manifests itself in the form of: changes in blood pressure, skin temperature, respiratory rate, pupil response, sweating, hormonal response, and much more.

Perhaps there is a question among women about how to turn on the limbic system in men. but answer simple: nothing. In all men, the limbus is fully functional (except for patients). This is justified by evolutionary processes, when a woman in almost all time periods of history was engaged in raising a child, which includes a deep emotional return, and, consequently, a deep development of the emotional brain. Unfortunately, men can no longer reach the development of a woman's limbus.

The development of the limbic system in infants largely depends on the type of upbringing and the general attitude towards it. A stern gaze and a cold smile are not conducive to the development of a limbic complex, unlike a strong hug and a sincere smile.

5interactions with the neocortex

The neocortex and the limbic system are tightly connected by many pathways. Thanks to this combination, these two structures make up one whole of the human mental sphere: they combine the mental component with the emotional one. The new cortex acts as a regulator of animal instincts: before performing any action spontaneously evoked by emotions, human thought, as a rule, undergoes a series of cultural and moral inspections. In addition to controlling emotions, the neocortex is supportive. The feeling of hunger arises in the depths of the limbic system, and already the higher cortical centers that regulate behavior search for food.

Sigmund Freud, the father of psychoanalysis, did not bypass such brain structures in his time. The psychologist argued that any neurosis is formed under the yoke of suppression of sexual and aggressive instincts. Of course, at the time of his work there was still no data on the limbus, but the great scientist guessed about such brain devices. So, the more cultural and moral layers (super Ego - neocortex) an individual had, the more his primary animal instincts are suppressed (Id - limbic system).

Violations and their consequences

Based on the fact that the limbic system is responsible for many functions, this very many can succumb to various damage. The limbus, like other structures of the brain, can be subject to injury and other harmful factors, including hemorrhagic tumors.

The syndromes of the limbic system are rich in number, the main ones are as follows:

Dementia- dementia. The development of diseases such as Alzheimer's and Pick's syndrome is associated with atrophy of the limbic complex systems, and especially in the localization of the hippocampus.

Epilepsy... Organic disorders of the hippocampus lead to the development of epilepsy.

Pathological anxiety and phobias. Dysfunction of the amygdala leads to mediator imbalance, which, in turn, is accompanied by a disorder of emotions, which includes anxiety. Phobia, on the other hand, is an irrational fear in relation to a harmless object. In addition, imbalances in neurotransmitters trigger depression and mania.

Autism... At its core, autism is a deep and serious maladjustment in society. The limbic system's inability to recognize the emotions of others has dire consequences.

Reticular formation(or reticular formation) is a non-specific formation of the limbic system responsible for the activation of consciousness. After deep sleep, people wake up thanks to the work of this structure. In cases of its damage, the human brain is exposed to various disorders of switching off consciousness, including absence and syncope.

Neocortex

The new cortex is a part of the brain found in higher mammals. The rudiments of the neocortex are also observed in lower milk-sucking animals, but they do not reach high development. In humans, the isocortex is the lion's share of the total cerebral cortex, with an average thickness of 4 millimeters. The area of the neocortex reaches 220 thousand square meters. mm.

History of origin

At the moment, the neocortex is the highest stage of human evolution. Scientists managed to study the first manifestations of the new bark from representatives of reptiles. The last animals that did not have a new bark in the chain of development were birds. And only developed man possesses.

Evolution is a complex and lengthy process. Every kind of creature goes through a harsh evolutionary process. If a species of an animal could not adapt to a changing external environment, the species lost its existence. Why is man was able to adapt and survive to this day?

Being in favorable living conditions (warm climate and protein food), the descendants of humans (before the Neanderthals) had no choice but to eat and reproduce (thanks to the developed limbic system). Because of this, the mass of the brain, in terms of the duration of evolution, gained critical mass in a short period of time (several million years). By the way, the mass of the brain in those days was 20% more than that of a modern person.

However, all good things come to an end sooner or later. With the change of climate, the descendants had to change their place of residence, and with it, and start looking for food. Having a huge brain, descendants began to use it for finding food, and then for social involvement, because it turned out that by uniting in groups according to certain criteria of behavior, it was easier to survive. For example, in a group where everyone shared food with other members of the group, they had a better chance of survival (Someone picked berries well, others hunted, etc.).

From this moment began separate evolution on the brain separate from the evolution of the whole body. Since then, the appearance of a person has not changed much, but the composition of the brain differs dramatically.

What does it consist of

The new cerebral cortex is a congestion nerve cells forming a complex. Anatomically, 4 types of cortex are divided, depending on its localization -, occipital,. Histologically, the cortex consists of six balls of cells:

Molecular ball;
outer granular;
pyramidal neurons;
internal granular;
ganglionic layer;
muliform cells.

What functions does

The human neocortex is classified into three functional areas:

Sensory... This zone is responsible for the higher processing of the received stimuli from the external environment. So, ice becomes cold when information about the temperature enters the parietal region - there is no cold on the finger, but only an electrical impulse.
Associative zone... This area of the cortex is responsible for the communication between the motor cortex and the sensory cortex.
Motor area... All conscious movement is formed in this part of the brain.
In addition to such functions, the new cortex provides higher mental activity: intelligence, speech, memory and behavior.

Conclusion

To summarize, the following can be highlighted:

Due to two main, fundamentally different, structures of the brain, a person has a duality of consciousness. Over each action, two different thoughts are formed in the brain:
- “I want” - the limbic system (instinctive behavior). The limbic system occupies 10% of the total brain mass, low energy consumption
- “Should” is the neocortex (social behavior). The neocortex occupies up to 80% of the total brain mass, high energy consumption and limited metabolic rate

Cortex - the higher part of the central nervous system, which ensures the functioning of the body as a whole when it interacts with environment.

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

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

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

The structure of the cerebral cortex

The cerebral cortex has a six-layer structure

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

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

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

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

Inner granular layer is similar to the second layer in terms of the type of cells and the arrangement of fibers. In the layer there are bundles of fibers connecting different parts of the cortex.

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

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

Layer of polymorphic cells represented mainly by cells, the axons of which form corticothalamic pathways.

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

There are significant differences in the neuronal composition and cytological features of different parts of the cortex. Based on these differences, Brodman divided the cortex into 53 cytoarchitectonic fields (see Fig. 1).

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

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

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

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

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

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

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

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

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

Functional areas of the cerebral cortex

On a functional basis, sensory, associative and motor areas are distinguished in the cortex.

Sensory (sensitive, projection) areas of the cortex

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

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

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

Visual cortex

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

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

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

Auditory cortex

Located in the lateral groove of the temporal lobe in the area of the Heschl gyrus (AI, fields 41-42). The neurons of the primary auditory cortex receive signals from the neurons of the medial geniculate bodies. The fibers of the auditory tract, which conduct sound signals to the auditory cortex, are organized tonotopically, and this allows the neurons of the cortex to receive signals from certain auditory receptor cells of the organ of Corti. The auditory cortex regulates the sensitivity of the auditory cells.

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

Vestibular cortex

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

Olfactory cortex

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

Taste bark

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

The signals of smell and taste reach the neurons in the anterior part of the insular cortex, where, on the basis of their integration, a new, more complex quality of sensations is formed, which determines our attitude to the sources of smell or taste (for example, to food).

Somatosensory cortex

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

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

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

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

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

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

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

Damage to neurons in the area of the primary somatosensory cortex leads to a decrease in various types of sensitivity on the opposite side of the body, and local damage to a loss of sensitivity in a certain part of the body. The discriminatory sensitivity of the skin is especially vulnerable when the neurons of the primary somatosensory cortex are damaged, and the least painful one. Damage to neurons in the secondary somatosensory area of the cortex may be accompanied by impaired ability to recognize objects by touch (tactile agnosia) and skills in using objects (apraxia).

Motor areas of the cortex

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

Primary motor cortex

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

The efferent fibers of the pyramidal pathway begin from the pyramidal neurons Ml. Some of the fibers of this pathway follow to the motor neurons of the cranial nerve nuclei of the brain stem (corticobulbar tract), some - to the neurons of the stem motor nuclei (red nucleus, nuclei of the reticular formation, stem nuclei associated with the cerebellum) and some - to inter- and motor neurons of the spinal cord. brain (corticospinal tract).

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

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

Secondary motor cortex

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

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

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

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

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

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

Prefrontal cortex

Located in the area of field 8. Its neurons receive the main afferent signals from the occipital visual, parietal associative cortex, upper hillocks of the quadruple. The processed signals are transmitted along the efferent fibers to the premotor cortex, the upper hillocks of the quadruple, and the brainstem motor centers. The cortex plays a decisive role in the organization of movements under the control of vision and is directly involved in the initiation and control of eye and head movements.

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

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

Associative areas of the cortex

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

The parietal associative area of the cortex. Located in fields 5 and 7 of the superior and inferior parietal lobes of the brain. The area is bordered in front by the somatosensory cortex, in the back - by the visual and auditory cortex. The neurons of the parietal associative region can receive and activate their visual, sound, tactile, proprioceptive, painful, signals from the memory apparatus and other signals. Some neurons are polysensory and can increase their activity when they receive somatosensory and visual signals. However, the degree of increase in the activity of neurons in the associative cortex to the receipt of afferent signals depends on the current motivation, the subject's attention, and information retrieved from memory. It remains insignificant if the signal coming from the sensory regions of the brain is indifferent to the subject, and it increases significantly if it coincided with the existing motivation and attracted his attention. For example, when a monkey is presented with a banana, the activity of neurons in the associative parietal cortex remains low if the animal is full, and vice versa, the activity increases sharply in hungry animals that like bananas.

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

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

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

This area of the cortex plays a primary role in the formation of the higher mental functions of a person. It provides the formation of target attitudes and programs of conscious behavioral reactions, recognition and semantic assessment of objects and phenomena, understanding of speech, logical thinking... After extensive damage to the frontal cortex, patients may develop apathy, a decrease in the emotional background, a critical attitude towards their own actions and the actions of others, complacency, a violation of the ability to use past experience to change behavior. Patient behavior can become unpredictable and inadequate.

The temporal associative area of the cortex. Located in fields 20, 21, 22. Cortex neurons receive sensory signals from neurons of the auditory, extrastriatal visual and prefrontal cortex, hippocampus and amygdala.

After a bilateral disease of the temporal associative areas with the involvement of the hippocampus in the pathological process or connections with it, patients may develop pronounced memory impairments, emotional behavior, inability to concentrate (distraction). In some people, if the lower temporal region is damaged, where the center of face recognition is presumably located, visual agnosia may develop - the inability to recognize the faces of familiar people, objects, while maintaining vision.

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

The cerebral cortex is the center of human higher nervous (mental) activity and controls the performance 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 base of which consists of long myelinated axons of neurons. Outside, the hemisphere is covered by the gray matter or cerebral cortex, consisting of neurons, myelin-free fibers and glial cells, which are also contained in the thickness of the sections of this organ.

The surface of the hemispheres is conventionally divided into several zones, the functionality of which is to control the body at the level of reflexes and instincts. It also contains the centers of higher mental activity of a person, providing consciousness, assimilation of the information received, allowing to adapt in the environment, and through it, at the subconscious level, through the hypothalamus, the autonomic nervous system (ANS) is controlled, which controls the organs of blood circulation, respiration, digestion, excretion , reproduction, as well as 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 bark 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), providing the functional organization of the cerebral cortex.

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

connects 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 thought and cognitive processes;
consciousness, thinking is formed in it, and also intellectual work is realized;
manages speech centers and processes that characterize the psychoemotional state of a person.

At the same time, data is received, processed, stored due to a significant number of impulses that pass 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 takes place.

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 effect of electrical impulses on this part of the brain do not find a vivid 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 also indifferent to their appearance and outside opinions. Sometimes there are other violations in the implementation of the functions of this body:

lack of concentration of attention on household items;
manifestation of creative dysfunction;
disorders of the psychoemotional state of a person.

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

parietal zone - is 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 received 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 distinctive features:

neurons in its thickness are located in layers;
nerve centers are located in a specific place and are responsible for the activity of a specific part of the body;
the level of activity of the cortex depends on the influence of its subcortical structures;
it has connections with all the underlying structures of the central nervous system;
the presence of fields of different software cellular structure, which is confirmed by histological examination, while each field is responsible for the performance of some higher nervous activity;
the presence of specialized associative areas allows you 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 retain traces of neuronal excitation.

The cerebral hemispheres consist mainly of long axons, and also contains in its thickness clusters of neurons that form 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 the age of 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 the age of 18.

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

The neurons of this part of the brain are programmed to restore the damaged area through synoptic contacts, thus each of the cells actively tries to restore the damaged connections, which ensures the plasticity of the neural cortical networks. For example, when the cerebellum is removed or dysfunctional, the neurons connecting it with the terminal section begin to grow into the cerebral cortex. In addition, the plasticity of the cortex also manifests itself under normal conditions, when the process of learning a new skill 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 specific 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 sequentially connected devices: an analyzer, a closure apparatus of conditioned reflex connections and a working device. Weakness of the closure function of the cortex and trace manifestations can be observed in children with severe mental retardation, when the formed conditioned connections between neurons are fragile and unreliable, which entails learning difficulties.

The cerebral cortex includes 11 regions, 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 central nervous system, developed from the terminal section of the brain. Evolutionarily, the formation of this organ took place in stages, therefore it is customary to divide it into 4 types:

The archicortex or ancient cortex, due to atrophy of the sense of smell, has turned into the hippocampus formation and consists of the hippocampus and its associated structures. With its help, behavior, feelings and memory are regulated.
The paleocortex, or old cortex, makes up the bulk of the olfactory zone.
The neocortex or new cortex has a layer thickness of about 3-4 mm. It is a functional part and performs higher nervous activity: it processes sensory information, issues motor commands, and also forms a person's conscious thinking and speech in it.
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 interners, which have the ability to stop a 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 on micromodules with a homogeneous structure.

The basis of the system of micromodules is made up of stellate cells and their axons, while all neurons equally respond 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, and occurs due to the connection of the brain with neurons located in different parts the body, and the cortex provides synchronization of mental activity with organ motility 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 that make up it were used: chemical and physical stimulation, partial removal of areas, as well as the development of conditioned reflexes and registration of biocurrents.

The associative zone connects the received sensory information with the previously acquired knowledge. After processing, it generates a signal and transmits it to the motor zone. Thus, she participates in memorization, thinking and learning new skills. The associative areas of the cerebral cortex are located in proximity to the corresponding sensory zone.

The sensitive or sensory area 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;
gustatory;
olfactory.

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

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

Brains of grooves and crevices

The cerebral cortex is formed by several layers of neurons. Characteristic feature this part of the brain has 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 areas of the cerebral cortex. All of them are different in morphological characteristics and regulate different functions. Thus, 52 different fields are allocated, located in certain areas. According to Brodman, this division is as follows:

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

The nucleus 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 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 one - with the right side.

The posterior central gyrus of the 1st lobe of the hemisphere contains the nucleus of the analyzer of tactile sensations and it is also associated 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 area, the dimensions of which also differ in size and topography. Experts distinguish the following layers of the cerebral cortex:

The surface molecular one is formed mainly of dendrites, with a small dissemination of neurons, the processes of which do not leave the boundaries of the layer.
The outer granular consists of pyramidal and stellate neurons, the processes of which connect it to the next layer.
The pyramidal one 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, as well as 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 go beyond the cortex and connect various structures and parts of the central nervous system with each other.

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

Video: Cortex of the cerebral hemispheres

NEOCORTEX NEOCORTEX

(from neo ... and lat. cortex- bark, shell), new bark, neopallium, osn. part of the cerebral cortex. N. carries out the highest level of coordination of the brain and the formation of complex forms of behavior. In the course of evolution, N. first appears in reptiles, in which it is insignificant in size and is 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 subdivided into lobes: frontal, parietal, temporal, occipital, and mediobasal. In turn, the lobes are subdivided into regions, subregions and fields, differing 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 in mammals and especially in humans are collected in anatomically pronounced bundles (for example, the occipital-frontal bundle), providing simultaneous coordinated activity of dec. N.'s zones. As part of N., a naib, a complexly constructed associative cortex, is distinguished, edges in the process of evolution experiencing the greatest increase, while N.'s primary sensory fields are relatively reduced. (see CEREAL BRAIN).

.(Source: "Biological Encyclopedic Dictionary." - M .: Sov.Encyclopedia, 1986.)

See what "NEOCORTEX" is in other dictionaries:

The neocortex ...

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

neocortex- 3.1.15 neocortex: A new cerebral cortex that provides 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 new bark ... Comprehensive Medical Dictionary

neocortex- at, h. Evolutionarily ninety and most of the nerve tissues, from which the foreheads, the yang, the skinny and the strongest parts of the brain are stored ... Ukrainian Tlumachny vocabulary

NEOCORTEX (NOVAYA KORA)- Evolutionarily the newest and most complex of nerve tissues. The frontal, parietal, temporal and occipital lobes of the brain are composed of the neocortex ... Dictionary in psychology

Archi, paleo, neocortex ... Spelling dictionary-reference

cortex- the brain: the cerebral 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 ... ... Big psychological encyclopedia

The term cortex refers to any outer layer of cells in the brain. The mammalian brain has three types of cortex: the pyriform cortex, which has olfactory functions; old bark (archicortex), constituting the main. part… … Psychological 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). The 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- white matter, which includes the long myelin axons of nerve cells. On the outside, the hemispheres are covered with the cerebral cortex, which also consists of neurons, as well as glial cells and myelin-free fibers.

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

There is such a concept - "ancient crust". This is evolutionarily the most ancient structure of the cloak of the telencephalon of the cerebral cortex in all mammals. They also distinguish the "new bark", which is only outlined in lower mammals, but in humans it forms a large part of the cerebral cortex (there is also an "old bark", which is newer than the "ancient", but older than the "new").

Functions of the cortex

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

Inside the cerebral cortex, various electrical signals are generated (the type of which depends on the current state of the person). The activity of these electrical signals depends on the person's well-being. Technically, electrical signals of this type are described in terms of frequency and amplitude. More connections and localized in places that are responsible for supporting 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 information received is achieved due to the large number of nerve cells with processes.
Support for continuous interconnection between various organs, tissues, structures and systems of the body.
Formation and correct work of human consciousness, the flow of creative and intellectual thinking.
Control over the activity of the speech center and the processes associated with various mental and emotional situations.
Interaction with 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 at the moment modern science studied to the least extent. These areas are known to be practically immune to external influences. For example, if these departments are influenced by external electrical impulses, they will not give any reaction.

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

From the point of view of physiology, the importance of each section of the cerebral hemispheres is difficult to overestimate. Even those that have not been fully studied at the moment.

The 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 specific functions. They all interact with each other, doing common work. It is customary to distinguish several main layers of the bark:

Molecular. In this layer, a huge number of dendritic formations are formed, which are intertwined in a chaotic manner. The neurites are oriented parallel to each other and form an interlayer 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. The exact functions of this layer are still unknown.
External pyramidal. Contains many nerve cells with processes that vary in size. Neurons are predominantly conical in shape. The dendrite is large.
Internal granular. It includes a small number of small neurons that are located at some distance. Fibrous grouped structures are located between nerve cells.
Internal pyramidal. Nerve cells with processes that enter it are large and medium in size. The top 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, functional component of their elements. The layers contain neurons of pyramidal, spindle, stellar, branchy species. Together they create over 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 receiving and processing impulses (that is, incoming information), creating 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 certain 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 have had latent birth injuries in the spine have a significantly smaller cerebral cortex than their healthy peers.

Prefrontal cortex

A large section of the cerebral cortex, which is presented in the form of the anterior sections of the frontal lobes. With its help, control, management, focusing of any actions that a person commits is carried out. This department allows us to properly allocate our time. The famous 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 a person.

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

Concentration of attention, focusing on obtaining only the information a person needs, ignoring outside thoughts and feelings.
The ability to "reboot" the mind, directing it in the right mental channel.
Perseverance in the process of performing certain tasks, striving to obtain the intended result, despite the emerging circumstances.
Analysis of the current situation.
Critical thinking, allowing 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 set goals.
Forecasting events.

Separately, the ability of this department to control 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 functions are attributed to different structures of the cerebral cortex. There is still no consensus on this issue. The international medical community currently concludes 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.

Area responsible for processing impulses

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.

There is also a 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 cortex of the head is damaged in this area, then the person will have 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 zone

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

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

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

Violations of the sensory zone will not always lead to the loss of some 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.

Associative 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 to these centers. The associative zone forms behavioral reflexes, takes part in the processes of their actual implementation. Occupies a significant (comparatively) part of the cerebral cortex, covering the sections included in both the frontal and the 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 front or back sections of the associative zone are damaged, then this can lead to certain problems. For example, in case of defeat of the above-mentioned departments, a person will lose the ability to competently analyze the information received, will not be able to make simple 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 parts).

Different areas of the cerebral cortex are responsible for certain functions. There are several methods to consider and determine the difference: neuroimaging, comparison of patterns of electroactivity, study of cell structure, etc.

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

Many of Brodmann's fields were initially determined based on 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 of Brodmann's fields (for example, zone 25 of the brain, as well as fields 12-16, 26, 27, 29-31 and many others) are not fully understood.

Reciprocating zone

A well-studied area of the cerebral cortex, which is also commonly called the center of speech. The zone is conventionally divided into three large sections:

Broca's propulsion center. Forms a person's ability to speak. Located in the posterior gyrus of the anterior part of the cerebral hemispheres. Broca's center and the motor center of the 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, however, the speech will cease to be clear, and the voice will become low-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 an infant in the first months of life). Such disorders are usually called motor aphasia.
Wernicke's sensory center. Located in the temporal region, it 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). What the patient says will be a collection of incoherent sounds. If there is a simultaneous defeat of the centers of Wernicke and Broca (this usually occurs with a stroke), then in these cases the development of motor and sensory aphasia is observed at the same time.
Center of perception written speech... It is located in the visual part of the cerebral cortex (field number 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 a relatively large brain size (in the general sense, and not in comparison with body size) have a sufficient thick cerebral cortex. For example, in field mice, its thickness is about 0.5 mm, while in humans it is 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 by means of MRI), it is possible to measure with high accuracy the thickness of the cerebral cortex in any mammal. Moreover, in different areas of the head, it will vary significantly. It is noted that the cortex is much thinner in the sensory zones than in the motor (motor) ones.

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

Furrows, convolutions, cracks

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

A cleft is a large groove dividing the mammalian brain into parts, into two hemispheres (longitudinal medial cleft).
A groove is a shallow depression that surrounds the convolutions.

At the same time, many scientists consider such a division into grooves and crevices to be very conditional. This is largely due to the fact that, for example, the lateral groove is often called the "lateral fissure", and the central groove, 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.