Frontal lobe: functions, structure and damage

Frontal lobe

Unfortunately, modern psychiatrists do not know very well the main sections of general neurology, in particular, topics. This gap largely determines errors in the diagnosis and treatment of mental disorders. Information about individual brain structures and comparison of the functional activity of the latter with the clinical symptoms of mental disorders seems significant in terms of etiology and pathogenesis. From the point of view of phylogeny and ontogeny, as the most recent formation, the frontal lobe should probably determine to the greatest extent the specificity of many psychopathological symptoms. In neurology, common causes of damage to the frontal lobe are usually strokes, tumors and injuries, in psychiatry - personality disorders, schizophrenia; After all, the pathology of this brain structure is manifested primarily by personality disorders and abulia. Both psychiatrists and neurologists are well aware that dementia is caused by damage to the frontal lobe, since the latter is responsible for such cognitive abilities as thinking and speech. When examining a patient, a neurologist will suspect severe pathology of the frontal lobe by deviation of gaze towards the lesion, motor aphasia, hemiparesis and partial seizures. Touching upon individual areas of the frontal lobe, we should focus on the connections and functional activity of the oribitofrontal cortex, which is located at the base of the frontal lobes. It has direct inputs from the dorsomedial thalamus, temporal cortex, and ventromedial tegmental area. Indirect connections come to it from the amygdala and olfactory cortex, projected into the singular and temporal cortex, the hippocampal system, the lateral hypothalamus and the amygdala. The oribital frontal cortex is also connected to other areas of the frontal lobes of the brain. Damage to the orbital-frontal cortex causes a weakening of the inhibition process and difficulty in the ability to independently concentrate attention, and the interests of the individual change noticeably. In the mid-twentieth century, lobotomy was popular among psychiatrists. However, later numerous studies showed that lobotomy leads not only to a decrease in intellectual level, but also to irresponsible behavior. Patients stop planning their actions, being responsible for them and, as a result, lose their ability to work and the ability to live independently. The purpose of the lobotomy was to separate the prefrontal region from the rest of the brain. It was assumed that the more active the prefrontal cortex, left temporal region (amygdala), and pons are involved, the more pronounced the psychomotor arousal and the higher the amplitude of the indicative skin galvanic response (Raine et.al., 1991). In child psychiatry, pathology of the frontal lobe also plays a special role; for example, in autism, there is a significant increase in the size of the frontal cortex, with the volume of white matter increased by 20% and gray matter by 13%. The changes mainly affect the medial and dorsolateral surfaces of the cortex. Disruption of brain development processes in autism leads to the preservation of an excessive number of short connections established in the early stages of ontogenesis, and to the underdevelopment of long ones that provide connections between distant brain structures. The consequence of this is a violation of the integration of mental functions at all levels (perception, thinking and speech) with normal or even hypertrophied development of individual abilities and excessive motor activity. Pathology of neural columns (inhibitory interneurons) leads to an imbalance in the “excitation-inhibition” processes. As a result, spontaneous activation of individual zones, in particular the subcortical nuclei and cerebellum, increases. Clinically, this manifests itself as obsessive movements, overexcitement, and other symptoms of autism. Dimyelination of fibers in adolescence determines the pathology of the white and gray matter zones, creating a picture of an intellectual defect and a violation of emotional and personal development (Pereverzeva D.S., Gorbachevskaya N.A., 2008). According to evolutionary teaching, the neocortex (isocortex) developed in humans relatively quickly and extensively, especially in the late period of its development, however, it played a dominant role, ensuring the integration of higher cerebral processes. In biological psychiatry and neuropsychiatry, the cortical fields of the frontal cortex, as well as the temporal cortex, explain the etiology and pathogenesis of many mental disorders. To a lesser extent, this probably applies to the parietal cortex. The cerebral cortex, covered by the pia mater, is represented on its surface by numerous dendrites that come from deep-lying cells. The long axons of pyramidal cells extend through the internal capsule to the pyramidal tract (layer 5). Granular cells (layer 4) mainly receive information from the sensory afferent pathways of the thalamus. The frontal cortex is predominantly composed of pyramidal cells, which typically use glutamate as a neurotransmitter. Processes associated with cholinergic neurons are also active in the cerebral cortex. The frontal lobe cortex is responsible for the control of motor behavior (motor activity. The term “prefrontal cortex” refers to the anterior part of the frontal lobe. It distinguishes the frontal granular cortex and the frontal associative cortex (Brodmann areas 9-15, 46, 47). In its deep (middle) ) part of the “prefrontal cortex” represents myelin in the late period of its development.Projections from the mediodorsal thalamic nuclei are sent to the “prefrontal cortex”.

What fields are included?

Fields and subfields are responsible for specific functions that are generalized under the frontal lobes. Because The polymorphism of the brain is enormous; the combination of the sizes of different fields makes up a person’s individuality. Why do they say that over time a person changes. Throughout life, neurons die, and the remaining ones form new connections. This introduces an imbalance in the quantitative ratio of connections between different fields that are responsible for different functions.

Not only do different people have different margin sizes, but some people may not have these margins at all. Polymorphism was identified by Soviet researchers S.A. Sarkisov, I.N. Filimonov, Yu.G. Shevchenko. They showed that the individual ways in which the cerebral cortex is structured within one ethnic group are so great that no common features can be seen.

• Field 8 - located in the posterior parts of the middle and superior frontal gyri. Has a center for voluntary eye movements
• Area 9 - dorsolateral prefrontal cortex
• Area 10 - Anterior prefrontal cortex
• Area 11 - olfactory area
• Area 12 - control of the basal ganglia
• Field 32 - Receptor area of ​​emotional experiences
• Area 44 - Broca's Center (processing information about the location of the body relative to other bodies)

• Field 45 - music and motor center
• Field 46 - motor analyzer of head and eye rotation
• Field 47 - nuclear zone of singing, speech motor component Subfield 47.1
• Subfield 47.2
• Subfield 47.3
• Subfield 47.4
• Subfield 47.5

Stereognosis, stereognosis

Complex types of sensitivity are localized in the cerebral cortex at the level of the superior parietal lobule, where there is no somatotopy. Complex types of sensitivity include stereognostic sensitivity (stereognosis, stereognosis), two-dimensional spatial sensitivity, a sense of localization and discrimination. The visual projection zone (visual cortex) occupies the area of ​​the calcarine sulcus - the inner surface of the occipital lobe. The auditory projection zone (auditory cortex) occupies the center of the superior temporal gyrus and Heschl's gyrus. The vestibular projection zone is located next to the auditory zone. The olfactory projection zone is localized on the inner surface of the temporal lobe, in the gyrus of the hippocampus. The gustatory projection zone is located next to the latter, as well as in the area of ​​the tire and the Reili island.

Function creates the center

According to Ivan Petrovich Pavlov: “Function creates the center!” In early childhood, the boundaries of the cortical centers are diffuse and less differentiated, and only as life experience is gained, a gradual concentration of functional zones occurs, and therefore in children of the first years of life, focal cortical symptoms are weakly expressed and general cerebral symptoms often predominate.

4. Significant differences in the localization of simpler and more complex functions. The simpler the function, the more accurately it is localized. Conversely, the most complex functions are determined by the integrative activity of the entire brain, therefore the concept of “cortical center” (section of the cerebral cortex, fields of the cerebral cortex, areas of the cerebral cortex, parts of the cerebral cortex) is in most cases relative and conditional. Simple cortical functions include sensory function, motor function, visual function, auditory function, vestibular function, olfactory function, and gustatory function. Complex cortical functions include speech, writing, reading, counting, praxis, gnosis, thinking, and memory.

Areas of the cerebral cortex

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

Cerebral cortex treatment

Sarclinic uses proprietary methods to restore the functioning of the cerebral cortex. Treatment of the cerebral cortex in Russia in adults, adolescents, children, treatment of the cerebral cortex in Saratov in boys and girls, boys and girls, men and women allows you to restore lost functions. In children, the development of the cerebral cortex and brain centers is activated. In adults and children, atrophy and subatrophy of the cerebral cortex, disruption of the cortex, inhibition in the cortex, excitation in the cortex, damage to the cortex, changes in the cortex, pain in the cortex, vasoconstriction, poor blood supply, irritation and dysfunction of the cortex, organic damage, stroke, detachment are treated , damage, diffuse changes, diffuse irritation, death, underdevelopment, destruction, diseases, perinatal encephalopathy and post-resuscitation encephalopathy, cerebral palsy, minimal cerebral dysfunction, delayed speech development, delayed psychomotor development, FMR, birth trauma. Cells and neurons of the cortex restore their work, structure and function are restored. The structure and activity of the cerebral cortex is restored, polypeptides and their content return to normal, the cortex and subcortex begin to work. In children, age-appropriate maturation of the cerebral cortex occurs. Unfortunately, under certain pathological conditions, death occurs, the death of cells in the cerebral cortex; in this case, it is not possible to restore the functioning of the cortex. On the website sarclinic.ru you can ask a doctor a question online for free. If the cerebral cortex is damaged, then with proper and adequate treatment it is possible to restore its functions.

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

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Literature

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3. Kayser AS et al. Dopamine, corticostriatal connectivity, and intertemporal choice // Journal of Neuroscience. – 2012. – T. 32. – No. 27. – pp. 9402-9409.
4. Panagiotaropoulos TI et al. Neuronal discharges and gamma oscillations explicitly reflect visual consciousness in the lateral prefrontal cortex // Neuron. – 2012. – T. 74. – No. 5. – pp. 924-935.
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Memory, memory function

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

Symptoms of the lesion

Symptoms of the lesion are revealed in such a way that the selected functions are no longer adequately performed. The main thing is not to confuse some symptoms with laziness or imposed thoughts on this matter, although this is part of frontal lobe diseases.

• Uncontrollable grasping reflexes (Schuster reflex)
• Uncontrolled grasping reflexes when the skin of the hand is irritated at the base of the fingers (Yanishevsky-Bekhterev Reflex)
• Extension of the toes due to irritation of the skin of the foot (Hermann's sign)
• Maintaining an awkward arm position (Barre's sign)
• Constantly rubbing your nose (Duff's sign)
• Speech Impairment
• Loss of motivation
• Inability to concentrate
• Memory impairment

The following injuries and illnesses may cause these symptoms:

• Alzheimer's disease
• Frontotemporal dementia
• Traumatic brain injuries
• Strokes
• Oncological diseases

With such diseases and symptoms, a person may not be recognizable. A person may lose motivation, and his sense of defining personal boundaries becomes blurred. Impulsive behavior associated with the satisfaction of biological needs is possible. Because disruption of the frontal lobes (inhibitory) opens the boundaries to biological behavior controlled by the limbic system.

Praxis, praxis analyzer, praxis center

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