How does the cerebral cortex? Areas of the cerebral cortex

Currently, it is known that the higher functions of the nervous system, such as the ability to realize the signals received from the external environment, to mental activity, memory and thinking, is largely due to the functioning of the cerebral cortex. Areas of the cerebral cortex we will consider in this article.

That the person is aware of your relationships with other people, due to the excitation of neural networks. We are talking about those who are found in the cortex. It is the structural basis of intelligence and consciousness.

Neocortex

About 14 billion neurons does the cerebral cortex. Areas of the cerebral cortex, which will be discussed below, are functioning thanks to them. The main part of the neurons (about 90 %) forms the neocortex. It belongs to the somatic nervous system, as his higher integrative Department. The most important function of the neocortex – processing and interpretation of information received through senses (visual, somatosensory, gustatory, auditory). It is also important that complex muscular movements controls it. In the neocortex there are centers that participate in the processes of speech, abstract thinking and memory retention. The main part of the processes occurring in it, is a neuro-physical basis of our consciousness.

Paleocortex

Paleocortex - another large and important division of the cerebral cortex. Areas of the cerebral cortex related to it, also very important. This part has a more simple structure in comparison with the neocortex. Processes here, in the consciousness reflected not always. In paleocortex are of the highest autonomic centers.

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Connectivity of the cortex with the lower parts of the brain

It Should be noted the relationship of the cortex with the lower parts of our brain (thalamus, basal nuclei, the bridge and mid brain). It is accomplished with large bundles of fibers that form the internal capsule. These bundles of fibers represent broad layers, composed of white matter. They contain a number of nerve fibers (millions). Some of these fibers (the axons of neurons of the thalamus) ensures the transmission to the cortex nerve signals. The other part, namely the axons of cortical neurons is to transmit them to the nervous centres, located below.

Structure of the cerebral cortex

Do you Know what part of the brain is the largest? Some of you probably guessed what was going on. It is the cerebral cortex. Areas of the cerebral cortex is only one type of parts, which are allocated in it. So, it is divided into right and left hemisphere. They are connected by bundles of white matter that forms the corpus callosum. The main function of the corpus callosum is to ensure the coordination of the activities of the two hemispheres.

Areas of the cerebral cortex by location

Although the cortex has many folds, in General, the location of major fissures and convolutions is constant. Therefore, the main of them serve as a guide for dividing the regions of the cortex. Its outer surface is divided into 4 lobes by three fissures. These shares (the zone) – the temporal, occipital, parietal and frontal. Although they are distinguished by location, each of them has their own specific function.

The Temporal area of the cerebral cortex is the center where the cortical layer of the auditory analyzer. In the case of damage occurring deafness. The auditory area of the cerebral cortex, but also has the speech center of Wernicke. In the case of damage lost the ability to understand spoken language. It is perceived as noise. In addition, the temporal lobe has neural centers related to vestibular system. Sense of balance is disrupted in case of damage.

Areas of speech cortex are concentrated in the frontal lobe. Here is rededicating center. If the right hemisphere it will be damaged, lost the ability to change the tone and timbre of speech. It becomes monotonous. If the damage relates to the left hemisphere, which also includes the speech areas of the cerebral cortex, lost the articulation. Disappears also the ability to sing and articulate speech.

The Visual area of the cerebral cortex corresponds to the occipital lobe. Here is a Department, which is responsible for our vision as such. The world we perceive it is the brain, not the eyes. The sight that meets just the back. Therefore, if damage develops partial or complete blindness.

Parietal share also has its own specific function. She is responsible for analyzing information relating to the General sensitivity tactile, thermal, pain. In case of damage, lost the ability to recognize objects by touch as well as some other abilities.

Motor area

I would Like to talk about it. The fact that the motor area of the cerebral cortex is not correlated with the shares about which we told above. It is a part of the cortex, which contains direct descending connections with the spinal cord, more specifically his neurons. The so-calledthe neurons that directly control muscles.

Main motor area of the cerebral cortex located in the precentral gyrus. In many aspects this gyrus is mirroring another zone, touch. Observed contralateral innervation. In other words, the innervation occurs in relation to the muscles located on the opposite side of the body. The exception is the front region in which the bilateral control of muscles of the jaw and lower face.

Another motor area of the cerebral cortex located in the area located below the main zone. Scientists believe that it has independent functions associated with the output of motor pulses. This motor area of the cerebral cortex have also been studied by scientists. In the experiments carried out on animals, it was found that its stimulation leads to motor responses. And this happens even if the primary motor area of the cerebral cortex had been destroyed. In the dominant hemisphere she is involved in motivation speeches and in planning movements. Scientists believe that its damage leads to dynamic aphasia.

Areas of the cerebral cortex function and structure

As a result of clinical observations and physiological experiments carried out in the second half of the 19th century, the boundaries were established in regions, which are projected different receptor surface. Among the latest release as the senses to the outside world (skin sensitivity, hearing, vision) and those that are inherent in the organs of motion (kinetic or motional analyzer).

The Occipital region – area of the visual analyzer (fields 17 through 19), the upper temporal lobe-auditory analyzer (fields 22, 41 and 42), the postcentral region – skin-kinesthetic analyzer (fields 1, 2 and 3).

Cortical representatives of different analyzers on the functions and structure of are divided into the following 3 zones of a bark of the big hemispheres of the brain: primary, secondary and tertiary. In the early period during the development of the embryo is laid the primary, which are characterized by a simple cytoarchitecture. In the least developed tertiary. They have the most complex structure. An intermediate position from this point of view is a secondary zone of the hemispheres of the cerebral cortex. Offer you learn more to review the functions and structure of each of them, and their relationship with parts of the brain, located below, in particular, to the thalamus.

Central field

Scientists over many years of study have gained considerable experience of clinical research. As a result of observations it was established, in particular, damage to those or other fields in the cortical representatives of the analyzers impact on the overall clinical picture is far from equal. Among the other fields in this respect is one which in the nuclear area occupies a Central position. It's called primary, or Central. It is field number 17 in the visual area, auditory – at number 41, and kinesthetic – 3. Their damage leads to very serious consequences. Lost the ability to perceive or to carry out the most subtle differentiation of stimuli of the respective analyzers.

Primary zone

In the primary zone is the most developed set of neurons, which is adapted to ensure that cortical-subcortical bilateral ties. It is the shortest and most direct route connects the cortex with a particular sense organ. Because of this, the primary area of the cerebral cortex can be sufficiently detailed to distinguish the stimuli.

An Important common feature of functional and structural organization of these areas – that all of them have a clear somatotopically projection. This means that individual points of the periphery (the retina, the skin surface of the cochlea of the inner ear, skeletal muscles) are projected in the relevant, clearly identified the points that are in the primary cortex of the corresponding analyzer. For this reason they were called the projection.

Secondary area

Otherwise, call them peripheral, and for good reason. They are located in the nuclear areas of cortex in their peripheral portion. Secondary zones differ from primary, or Central, on the physiological manifestations of neural organization and features of the architectonics.

What effects are observed when electrical stimulation or defeat? These effects relate mainly to more complex mental processes. If the secondary zones are affected, the basic feeling relatively safe. Upset basically the ability to reflect mutual relations and the whole complexes of the constituent elements of the various objects that we perceive. If annoyed secondary areas of the auditory and visual cortex, the observed auditory and visual hallucinations that are deployed in sequence (temporal and spatial).

These areas are important for the implementation of the mutual relations of the stimuli, the allocation of which occurs with the primary zones. In addition, they play a significant role in integrating the functions of the nuclear fields of different analyzers at Association reception in complex systems.

A Secondary zone, suchway, important for the implementation of more complex forms of mental processes that require coordination and associated with a careful analysis of the ratios of subject stimuli, and also with orientation in time and in the environment. This set of relations, called asotsialnym. Afferent impulses from receptors in different surface sense organs are sent to the cortex, reach the field data using a variety of additional switches in asotsialnyh nuclei of the thalamus (optic thalamus). In contrast, the afferent impulses that follow in the primary zone, reach them shorter path through the relay-the nucleus of the optic hill.

What is the thalamus

The Fibers from the thalamic nuclei (one or several) appropriate to each lobe of the hemispheres of our brain. The optic thalamus, or thalamus, located in the front brain, in its Central region. It consists of many nuclei, each of them passes the impulse on a specific area of the cortex.

All inputs (except olfactory) pass through the relay and integrative nuclei of the thalamus. Next, the fibers going from them to the sensory areas (parietal lobe-taste and somatosensory, temporal-auditory in the occipital – to visual). Received impulses, respectively, of the ventro-basal complex, the medial and lateral nuclei. With regard to motor areas of the cortex, they have a connection with ventrolateral and anterior ventral nuclei of the thalamus.

Desynchronization of the EEG

What if the person who is at rest, suddenly to present any strong stimulus? Of course, he immediately alert and concentrate on that stimulus attention. The mental transition of activities from quiet to active state, corresponds to a replacement of the alpha rhythm of the EEG beta rhythm, as well as other variations, more frequent. This transition, called desynchronization of the EEG appears in the result of the fact that the cortex from the nonspecific nuclei of the thalamus receives sensory stimulation.

Reticular Activating system

Nonspecific nuclei are diffuse nerve network located in the thalamus, in the medial departments. This anterior ARS (reticular activating system), which regulates the excitability of the cortex. Different sensor signals can activate ARS. They can be visual, vestibular, somatosensory, olfactory and auditory. ARS – it is a channel through which data signals are transmitted to the superficial layers of the cortex through nonspecific nuclei located in the thalamus. The initiation of ARS plays an important role. It is essential to maintain a wakeful state. In experimental animals, in which the system had been destroyed, were observed in a comatose dream-like state.

Tertiary zone

The Functional relationship can be traced between analyzers, even more complex than described above. Morphologically further complication is that in the process of growth on the surface of the hemisphere nuclear field analyzers these areas mutually overlap. At the cortical ends of the analyzers are "areas of overlap", that is, the tertiary zone. These formations are among the most complex types of enterprises activities of skin-kinesthetic, auditory and visual analyzers. Tertiary zones are located already beyond the boundaries of their own nuclear fields. Therefore, their irritation and damage leads to severe loss events. Also in terms of the specific functions of the analyzer are not observed significant effects.

Tertiary zone – this is a special region of the cortex. They can call the collection "scattered" elements of the various analyzers. That is, elements that in themselves are not capable of producing any complex synthesis or analysis of the stimuli. The territory they occupy quite extensive. It is divided into a number of areas. Briefly describe them.

The Upper parietal region is important for integrating full body movements with visual analyzers, as well as to generate the schema body. As for the bottom vertex, then it belongs to the Association of abstract and generalized forms of alarms associated with complex and subtly differentiated speech and substantive actions, the implementation of which is monitored by the vision.

The Region of the temporo-parieto-occipital is also very important. It is responsible for the complex integration of visual and auditory analyzers with written and oral speech.

Note that the tertiary zones have the most complex circuit when compared to primary and secondary. Bilateral relationships are they with the complex nuclei of the thalamus, associated in turn with relay nuclei through a long chain of internal connections available directly to the thalamus.

Based On the foregoing, it is clear that a person area of primary, secondary and tertiary represent the areas of cortex that are highly specialized. It is especially necessary to emphasize that 3 groups of cortical zones, as described above, in the normally working brain along with systems, linkages and switches with each other and with subcortical formations function as one difficult differential unit.