Auditory recognition disorders (auditory agnosia). Agnosia: visual, auditory agnosia, treatment of agnosia Agnosia treatment

In today's article we will talk about such an unpleasant phenomenon as agnosia. This condition is characterized by the fact that during its development against the background of damage to the cerebral cortex in a person, various disorders are violated. As a rule, agnosia is a pathology that appears against the background of chronic diseases (problems with the circulation of the brain, poisoning). In addition, it causes damage to the secondary sections of the cerebral cortex, which are part of the analyzer system of the cortical level.

Causes

As already mentioned, agnosia affects the parietal and occipital lobe of the human head. This may be due to such reasons:

• Acute problems with blood circulation in the brain (stroke).
• When tumors appear.
• Due to a traumatic brain injury, which could have arisen due to several reasons (accident, fall from a great height, impact).
• Disorders of blood flow in the brain, which later leads to dementia, which can both manifest as tearfulness and cause certain difficulties in mastering new skills, orienting in various everyday situations and contribute to the emergence
• Due to the development of inflammation of the brain (encephalitis).
• Due to Parkinson's disease, which is characterized by the appearance of progressive muscle stiffness, tremors and neuropsychological disorders.

In addition, it should be borne in mind that agnosia is a phenomenon that occurs suddenly. Therefore, you should be as attentive as possible to the state of your health and undergo regular medical examinations in a timely manner.

Symptoms

The most common symptoms include:

• Difficulties associated with orientation on the ground.
• Denial of the presence of diseases or defects associated with a sharp appearance of weakness in the limbs, despite their acute manifestation.
• Indifference to the presence of various defects listed above.
• Problems associated with the tactile definition of objects and their texture.
• Disorders associated with the definition of sound. As a rule, such a human condition is classified as auditory agnosia, in which the patient cannot not only clearly determine the nature of the sound, but also indicate the place where it sounds from.
• Problems with the perception of your body.
• Inability to recognize intricate visual images. Although a person retains the ability to fix some elements, but at the same time he is not able to connect them together. For example, looking at, he can recognize glasses, jugs, plates of food, but the reason for their appearance will remain a mystery to him. This condition is classified as visual agnosia.
• Taking into account only the visible space. As an example, a situation can be cited here when a patient eats only on the right side of the plate while eating, or when opening the door, he touches his left shoulder because he does not see the interference on the left.

A little about agnosia: types

Like every pathology, agnosia also has its own characteristics of the course, taking into account which an effective treatment regimen can be prescribed. That is why, before starting therapy, you need to know not only what this disorder is, but also its characteristic features.

To date, there are several forms of this condition:

1. Tactile agnosia.
2. Visual.
3. Auditory.

visual

As a rule, this type manifests itself when a violation occurs in the secondary part of the occipital cortex. It can be expressed as follows:

• In the absence of recognition of previously known objects, it is also called object agnosia. For example, a person finds it difficult to answer the question "what is it?" when looking at a phone or a book. But if you tell him what this item is called, then he will be able to say what it is intended for. In addition, as practice shows, object agnosia can have several degrees of severity - from the maximum (problems with recognizing real objects) to the minimum (difficulties with recognizing a contour image).
• Agnosia for faces, which is manifested by a violation of facial recognition of relatives or friends. But at the same time, the patient can indicate both the age and gender of the person without any problems.
• color agnosia, which is expressed by the fact that the patient cannot say exactly what color he sees at the moment in front of him. For example, if you ask a patient to look at a green leaf on a tree and say what color it is, you may not get an answer. But if you ask what it should be like, a person will answer this question without any problems.
• Simultaneous, or, as it is also called, simultaneous agnosia, which is characterized by a violation in recognizing a rather complex visual image, and this despite the fact that the very ability to recognize individual elements remains in perfect order.

Also, visual agnosia often manifests itself in a situation where a person is reading a book, but, despite all his desire, he cannot remember some letters or a single word. This leads to certain difficulties during reading, but in no way affects the letter, since when asked to reproduce a letter that eludes him on a piece of paper or type it on the keyboard, the patient does this without any problems.

auditory

As a rule, auditory agnosia manifests itself when the cortical field of the temporal lobe is damaged. So, if the temporal lobe of the hemisphere located on the left is damaged, this condition can be expressed as a disorder of phonemic hearing (difficulties in distinguishing speech sounds, which can later lead to speech disorder). With a damaged lobe of the hemisphere, which is located on the right, the sick person loses the ability to distinguish previously familiar musical sounds.

Tactile

Tactile agnosia develops when the secondary cortical field of the parietal part or hemisphere, located on the right side, is damaged. Its distinguishing feature is problems with the recognition of objects by touch or in a disorder associated with the recognition of one's own. As practice shows, this type can be divided into 2 categories. The first can be attributed to everything that is associated with skin receptors, and the second - with muscle and articular receptors.

Diagnostics

Having found similar symptoms in your friend or loved one, in order not to guess whether it is agnosia or not, it is best to carry out certain diagnostic measures. In addition, do not forget that the diagnosis is only half the battle. Therefore, it is imperative to contact an experienced specialist who will analyze the patient's complaints, take into account the history of the disease (prescription of the disease, signs, causes that led to the occurrence of this condition). In addition, it is important to take into account the rate of progression of pathology. After this, it may be necessary to conduct an assessment of mental functions and look for other possible neurological disorders. Their need is due to the fact that agnosia is a condition that is primarily associated with. If necessary, an interview with a neuropsychologist can be scheduled, during which you will probably need to perform several procedures (fill out a questionnaire, answer various questions).

We should not exclude the value of such types of research as MRI and CT scan, which can not only help in the layer-by-layer study of the structure of the brain, but also determine possible cause occurrence of agnosia.

Treatment

As a rule, after treatment is started, agnosia can slightly reduce its manifestations. But only after the elimination of the underlying disease can we talk about effective and effective therapy generally.

The treatment process itself may consist in the elimination of a brain tumor, control of blood pressure, sessions with a psychologist and the use of drugs that improve the state of neuropsychic functions.

The most important thing is not to self-medicate, as most people do. As practice shows, diagnostics carried out at the wrong time and, as a result, therapy started late can no longer 100% get rid of the manifestations of this pathology. In general, statistics show that if treatment is started on time, agnosia can almost completely disappear.

Prevention

At present, special preventive measures, which could prevent the development of agnosia, does not exist. From general recommendations can be distinguished:

• Refusal of alcohol and smoking.
• Doing healthy lifestyle life.
• Constant control of arterial pressure.
• Seek immediate medical attention at the slightest sign of this condition.

Agnosia is a secondary disease that develops as a result of brain damage. Depending on the localization of the damaged area and its functions, various symptoms- impaired vision, hearing, development, while the organs are absolutely healthy and do their job perfectly. Treatment of the disease depends on the causes of its development, the form and severity of the disease. Doctors say that with a timely start and proper treatment a favorable outcome and complete elimination of symptoms are possible. What types of agnosia exist, what contributes to its development and how to get rid of the disease, you can find out by reading the information below.

What is agnosia?

Agnosia is a disease, a set of symptoms that are characterized by a violation of the perception of the surrounding world as a result of damage to the cerebral cortex and its cells directly. As a rule, this is a secondary ailment that occurs due to diseases that have a negative impact on the brain. Depending on which area is affected, various perception disorders occur (auditory, visual, tactile, and others). With the development of the disease, all organs function normally, but the brain is not able to process the information and understand it.

Reasons for the development of the disease

The development of agnosia contributes to the brain damage that occurs as a result of the disease. An important nuance is that in right-handed people the disease develops when the left hemisphere is damaged, in left-handed people it is vice versa. Main pathological changes that provoke the development of agnosia is:

• Circulatory disorders, for example,.
• encephalopathy.
• Tumor diseases of the brain.
• Traumatic brain injury.

Types of agnosia

There are several types of agnosia. In order to find out how they differ and how they manifest themselves, one should consider each.
auditory agnosia. This form of the disease develops as a result of damage to the area of ​​\u200b\u200bthe brain responsible for hearing and recognizing extraneous speech. In the case of damage to the right hemisphere, the patient is not able to recognize any external sounds. If damaged left hemisphere(temporal lobe), there is a violation of phonetic hearing, a person cannot distinguish between human speech, which leads to a disorder of speech function.

With damage to the anterior (frontal) areas of the brain, the patient can hear and speak, but is not able to adequately perceive information, analyze it and understand it. As a rule, this happens with the development of mental illness or disorders.

visual agnosia. With this type of disease, the ability to recognize objects and give them a name is impaired. At the same time, vision is absolutely normal and there are no eye lesions. This form develops with damage to the occipital region of the cerebral cortex. In turn, visual agnosia is divided into several subspecies:

• Color agnosia is a violation of the perception and difference of colors.
• Simultaneous agnosia is the inability to perceive a group of images as a whole. At the same time, the patient retains the ability to distinguish objects and images separately. This form develops with damage to the parietal, temporal and occipital regions of the brain.
• Letter agnosia - a violation of the patient's ability to recognize letters, respectively, a person loses reading and writing skills. This disease is popularly known as "acquired illiteracy". The disease develops when the occipital region of the dominant hemisphere of the brain is affected.

Symptoms characteristic of this form:

• The patient easily describes the characteristics of the object in front of him (shape, purpose, material, color), but cannot name it. For example, when showing a white electric kettle to a patient, he can say that this is an attribute for heating water, name its color, but he is not able to give it a name.
• A person can recognize an object by sound or tactile sensations.
• The patient is unable to name an object if there is no part of it (for example, a bicycle without a wheel).
• Difficulties in compiling a whole picture, an object from separate parts.

Tactile agnosia. This is a perceptual disorder, which is characterized by the inability to recognize objects by touch. Occurs when the parietal region of the brain of the left or right hemisphere is damaged. There are several varieties of this form:

• Somatoagnosia is a violation of a person's ability to recognize body parts and determine their location relative to each other.
• Tactile agnosia - the inability to recognize the letters and numbers that are drawn on the patient's hand.
• Finger agnosia - the inability to determine the name of the fingers when touching them with the patient's eyes closed.
• Object agnosia is a violation of perception in which the patient cannot determine by touch the shape, size of an object or the material from which it is made.

Spatial agnosia. A form of the disease in which the patient is unable to navigate the terrain and recognize spatial patterns. An ailment appears when the parieto-occipital lobe of the brain is damaged. With the development of spatial agnosia, the patient cannot distinguish between left and right, swaps letters in words and words in sentences. When drawing, the patient can depict only part of the drawing, arguing that the second part does not exist a priori.
Symptoms of spatial agnosia:

• The patient can get lost in his own apartment, in his hometown.
• The patient confuses the perception of "up-down", "left-right".
• A person cannot draw a complete picture (he is able to depict individual parts of an object, but is not able to put everything together).
• Difficulties in orienting by the clock.

To general symptoms agnosia refers to:

• Denial by the patient of the presence of a disease or pathology, despite the presence of obvious signs.
• Indifference to existing symptoms, the patient does not pay attention to defects and does not attach special importance to them.

Diagnosis of the disease

To diagnose the disease, it is extremely important to consult a specialist - a neurologist. For an accurate diagnosis, a number of diagnostic techniques and neurological studies are carried out. The main goal of all research is to establish the root cause, the main disease that provoked brain damage.

Diagnostic methods that are used to establish a diagnosis:

• Careful examination of the patient, taking an anamnesis and clarifying the presence of hereditary diseases. Most often, during the study, tumor diseases, injuries, the consequences of a stroke and other diseases are detected.
• In addition, a consultation of highly specialized specialists is carried out to exclude other causes of symptoms. As a rule, help is required, and others.
• Conducting various tests that help determine the degree of perceptual impairment in order to differentiate the disease from other possible ones.
• Conducting computed and magnetic tomography. With the help of these procedures, it is possible to establish damaged areas of the brain.

Treatment of the disease

In medicine, there is no single protocol for the treatment of agnosia, since it depends on the root cause of the disease, its type and degree of neglect. In parallel with the treatment of the underlying ailment, work is being done with a neuropsychologist. This is necessary in order to help a person adapt to life in the presence of such pathologies. There are cases when the treatment brought instant results and when it dragged on for many years. The effect depends on how quickly the patient sought professional help. The most commonly used drugs are of the following groups: vascular drugs, neuroprotectors and nootropics, B vitamins.

Agnosia is an unpleasant and dangerous condition that can threaten health and interfere with a normal, fulfilling life. With timely seeking help, you can get rid of the symptoms and improve the condition. It is strictly forbidden to self-medicate, use methods traditional medicine or others unconventional ways without prior consultation with a specialist.

Gnosis (Greek gnosis - cognition, knowledge) - the ability to cognize, recognize objects, phenomena, their meaning and symbolic meaning from sensory perceptions. Violation of recognition with the relative preservation of elementary sensations and intellect is called agnosia. Primary agnosias develop when the secondary cortical zones of the corresponding sensory analyzer (the second block) are damaged and, therefore, are characterized by modal specificity, i.e., they are noted in one sensory modality. Secondary agnosia develops when the third block is affected - the block of programming, regulation and control of voluntary activity associated with the pathology of the frontal lobes or as a result of a decrease in the level of attention. In secondary agnosia, all sensory modalities are affected. A characteristic feature of agnosia is the difficulty or inability to recognize a holistic sensory image while maintaining the ability to distinguish and describe its individual features.

Agnosia is multivariate in its manifestations. Agnosia of external space is distinguished: visual, auditory, tactile, olfactory and gustatory, and agnosia of internal space or somatoagnosia: autotopagnosia, anosognosia, fingeragnosia.

Consider the characteristics of individual types of agnosia and methods for their study.

visual agnosia.

Visual agnosia occurs when the 18th and 19th cytoarchitectonic fields, which are the secondary fields of the visual analyzer, are affected, as well as the tertiary fields adjacent to them and the nearest subcortical zones.

To all forms visual agnosia One general rule applies:

elementary sensory visual functions remain relatively preserved, patients see well enough, they have normal color perception, normal visual fields.

There are 6 main forms of visual gnosis disorders:

object agnosia

Facial agnosia (prosopagnosia)

color agnosia

opto-spatial agnosia

Letter agnosia

Digital agnosia

Simultaneous agnosia.

The form of violation of visual gnosis is associated both with the side of the lesion and the location of the lesion in the occipital and parietal regions of the brain.

subject agnosia. In patients with object agnosia, the recognition of individual objects and their images is impaired due to the impairment of the ability to combine individual visual impressions into single whole images. In typical cases, patients find it difficult to recognize well-known objects, describing individual features of the object, they cannot say what it is. When examining a pen or a comb, they say that it is a narrow, long object, but do not recognize it. Feeling an object often helps to correctly recognize it. Unlike patients with amnestic aphasia, patients with visual agnosia not only cannot correctly name an object, but also cannot explain its purpose.

Especially gross violations of the ability to recognize an object occur with bilateral lesions of the occipital lobes or parietal-occipital regions, which is often observed in vascular pathology.

In everyday life, patients behave almost like blind people, and although they do not stumble upon objects, they constantly feel them or navigate by sounds.

In milder cases of object agnosia, recognition disorders are detected mainly upon presentation of real objects, their images (Fig. 1-11). Schematic contour images are especially difficult to recognize, with contours of the object superimposed on each other, missing parts of the object, object images against the background of "visual fields", the so-called "noisy drawings" - Poppelreiter's drawings (Fig. 12, 13).

With visual agnosia, the patient is not able to draw a given object, since he has a disturbed holistic perception of his image.

Facial agnosia or prosopagnosia characterized by impaired recognition of familiar faces with the relative preservation of objective gnosis. Patients recognize individual parts of the face (nose, eyebrows, eyes, ears) and the face as an object as a whole, but cannot recognize its individual affiliation, do not recognize the faces of relatives and friends.

In the most severe cases, patients do not recognize their own face in the mirror, do not recognize the features of facial expressions, and do not distinguish between the faces of men and women. Recognition of people in such cases is carried out by voice, clothing, gait. Facial agnosia often coexists with other forms of agnosia. Facial agnosia is associated with damage to the posterior parts of the right hemisphere in right-handers, the lower "visual sphere" - the occipital region, extending in some cases to the parietal and temporal regions.

This symptom is very common in Alzheimer's disease.

To diagnose prosopagnosia, the patient is presented with portraits of well-known people, some figures (Fig. 14) or photographs of relatives and close acquaintances of the patient, distinguishing them from strangers.

Agnosiaon colors called a violation of the ability to select the same colors or shades of the same color. Patients cannot determine the belonging of a particular color to a particular object.

Color agnosia is observed against the background of preserved color perception.

Such patients correctly name colors and distinguish them correctly, however, they find it difficult to determine the relationship of color to an object, they cannot say what color a carrot or an orange is. Due to the lack of generalized ideas about color, patients cannot classify colors.

Color agnosia is usually observed together with object agnosia, and occurs when the left occipital region is affected. Often, focal brain damage extends to the temporal region.

Letter agnosia. Patients, correctly copying the letters, cannot name them. Reading skills fall apart. Such a reading disorder occurs in isolation from other visual impairments with damage to the left hemisphere - the lower part of the visual sphere at the border of the occipital and temporal regions in right-handed people.

To diagnose letter agnosia, the patient is asked to name the letters in different fonts, crossed out or upside down, in a mirror image (Fig. 15).

Digital agnosia- a variant of visual agnosia, in which patients cannot name numbers. To diagnose digital agnosia, the patient is asked to name Arabic and Roman numerals and numbers in direct, crossed out, inverted, mirror image form (Fig. 15).

Opto-spatial agnosia. It is characterized by a violation of the possibility of orientation in the spatial features of the environment and images of objects. The ability to correctly localize objects in three coordinates of space, especially in depth, is impaired. It becomes impossible to estimate the distance to the object, the right-left orientation becomes difficult.

Patients forget the way to their home, are poorly oriented in a geographical map, navigate the street by the street name and house number, and cannot independently draw a picture (Fig. 16).

Unilateral spatial agnosia also belongs to this category of agnosia. Patients lose sight of half of the space, more often the left, spatial orientation is difficult due to errors related to one side of the space more often than the left (Fig. 16). Half of the space is ignored. The patient does not notice the presence of stimuli on the one hand; when redrawing the image, he reproduces only half of the picture.

Optical-spatial disorders are associated with foci localized in the parietal region (with bilateral lesions), sometimes to a greater extent in the left hemisphere. Violation of topographic orientation in diagrams, maps is associated with the localization of the focus in the left hemisphere, violation of orientation in real space - in the right. The syndrome of unilateral spatial agnosia is detected when the parietal region of the right hemisphere is affected, more often with ischemic stroke in the basin of the right middle cerebral artery.

Optical-spatial agnosia is usually combined with a violation of constructive praxis. This symptom is called opto-agnostic. The combination of these disorders with agraphia, alexia, amnestic aphasia, acalculia, fingeragnosia is called Gerstmann's syndrome. It occurs when the junction of the parietal, temporal and occipital regions of the dominant hemisphere is affected. To diagnose optical-spatial agnosia, the patient is asked to name the time by the hands of the clock, arrange the hands on a silent dial, name the main images on the contour map (Fig. 17,18), draw a plan of the ward, divide the line into parts.

Simultaneous agnosia characterized by a violation of the complex synthesis of visual images. This form of agnosia is characterized by the impossibility of perceiving two images. Correctly identifying individual objects, patients cannot assess the content of the picture. This form of impaired visual gnosis is called Ballint's syndrome. The occurrence of the syndrome is associated with a narrowing of the volume of visual perception, complex disorders of eye movements, the gaze becomes uncontrollable, which makes visual search difficult. The localization of the focal process in Ballint's syndrome is associated with a bilateral lesion of the occipital-parietal region.

auditory agnosia.

Auditory agnosia is a variant of sensory agnosia in which there is a disorder in the recognition of audible sounds. The patient does not recognize the sound of a car horn, barking dogs and other household noises.

Gnostic auditory disorders are associated with damage to the right hemisphere in the region of the superior temporal gyri, more precisely in the secondary cortical projection zones, fields 41,42,22 of Brodmann's architectonic map. With the defeat of the left hemisphere in the area of ​​similar cortical fields, another variant of auditory agnosia arises - deafness to words. At the same time, phonemic hearing is disturbed, in connection with which the understanding of addressed speech is also impaired. The patient hears the words, but does not understand their meaning. Usually this symptom noted within the sensory aphasia syndrome.

More often there is a more erased form of auditory impairment in the form of defects in auditory memory. The latter are manifested in special experiments, showing that a patient who is able to distinguish between pitch relationships cannot express auditory differentiations, i.e. remember two (or more) sound images.

With damage to the temporal region of the brain, a symptom such as arrhythmia may occur. The manifestation of arrhythmia is that patients cannot correctly assess the rhythmic structures that are presented to them by ear, and cannot reproduce them. One of the well-known defects in nonverbal hearing is called amusia. This is a violation of the ability to recognize and reproduce a familiar melody, or one that a person has just heard, as well as to distinguish one melody from another. Patients with amusia not only cannot recognize the melody, but also evaluate it as a painful and unpleasant experience. Music becomes unpleasant for them, often causing headaches. It is important to note that if the symptom of amusia manifests itself mainly with damage to the right temporal region, then the phenomenon of arrhythmia can be detected not only with right-sided, but also with left-sided temporal foci (in right-handed people). Finally, a symptom of damage to the right temporal region is a violation of the intonational aspect of speech.

Patients with such a defect not only do not distinguish speech intonations, but they themselves are not very expressive in their own speech. Their speech is devoid of modulations, intonation diversity. There are descriptions of patients with damage to the right temporal region, who, while repeating a single phrase well, could not understand the same phrase. Thus, auditory agnosias should include: proper auditory agnosia, auditory memory defects, arrhythmia, amusia, violation of the intonational aspect of speech.

Patients with auditory agnosia complain of hearing loss, auditory deceptions. However, an objective examination of ENT specialists does not reveal pathology.

To diagnose auditory agnosia, the patient is asked to recognize objects by sound, for example, by ringing - a bunch of keys, coins, by ticking - a clock; name famous musical melodies; important in the study of auditory gnosis and disorders of auditory-motor coordination is the assessment and reproduction of rhythms (Fig. 19); the patient is asked to determine the nature of the rhythms (single, double, triple beat, their alternation), to perform the rhythms according to the image with direct, delayed (empty) playback and after interference (II II II III III III); perform rhythms according to the speech instruction: hit 2, 3, 2, 4 hits with direct, delayed (after an empty pause) playback, after interference. At the same time, the decay of rhythmic structures and the presence of perseverations are assessed.

Tactile agnosia.

Tactile agnosia is characterized by the inability to differentiate objects by their texture when touched. Difficulties arise in recognizing such qualities of an object as roughness, softness, hardness, while maintaining superficial and deep sensitivity - the sensory basis of tactile perception.

Tactile agnosia occurs when secondary zones of the cortex of the parietal region are affected (1, 2, partially 5 fields - the upper parietal region) and tertiary zones (39, 40 fields - the lower parietal region).

With the defeat of the post-central areas of the cortex, which border on the zones

representation of the hand and face in the 3rd field, there is a violation of complex forms of tactile gnosis, known as astereognosis. This is a violation of the ability to perceive familiar objects by touch with eyes closed. Astereognosis manifests itself against the background of a preserved sensory basis of tactile perception, arises as a result of a violation of the synthesis of elementary sensations, a disorder of three-dimensional spatial perception. There are two forms of this disorder: in some cases, the patient correctly perceives the individual features of the object, but cannot synthesize them into a single whole, in others, the recognition of these features is also impaired.

Olfactory and gustatory agnosia.

These types of sensory agnosia are characterized by the loss of the ability to identify olfactory and gustatory sensations due to damage to the mediobasal regions of the temporal cortex.

Somatognosia.

Somatoagnosia - agnosia of the internal space. It arises as a result of a violation of the perception of one's own body, which develops from early childhood on the basis of tactile, kinesthetic, visual and other sensations. There are 3 variants of somatoagnosia: autotopagnosia, anosognosia and fingeragnosia (finger agnosia).

At autopagnosia the perception of the body scheme is disturbed. The patient loses the idea of ​​the localization of body parts, cannot, at the request of the doctor, show parts of his body. There is alienation of parts of your body. Separate parts of the body on the opposite side of the focus may appear to be changed in size and shape. There may be a sensation of a third arm or leg (pseudopolymelia), a doubling of the head, or the absence of any part of the body up to the sensation of the absence of limbs and the entire half of the body, usually the left. In this case, these manifestations can be considered as a variant of unilateral spatial agnosia.

Autopagnosia is observed when the cortex of the parietal lobe is damaged (fields 30.40) and the connections of the parietal cortex with the visual tubercle are more often in the right hemisphere, which usually occurs with tumors, strokes, and injuries. Somatognosia can also be one of the manifestations of derealization and depersonalization in epilepsy or schizophrenia.

At anosognosia(Anton's syndrome), the patient does not realize that he has disorders caused by the pathological process, denies their presence. Anosognosia can refer to paralysis, blindness. The patient claims that the movements of his limbs are not disturbed, that he can get up, but he does not want to get up. This syndrome occurs in cases of extensive damage to the parietal lobe of the subdominant hemisphere.

Fingeragnosia It is manifested by the indistinguishability of the fingers on one's hand while maintaining the muscular-articular feeling. The patient also cannot name the fingers that the doctor shows. Despite the absence of violations of superficial and deep sensitivity, patients are mistaken in recognizing passively moved fingers with their eyes closed. The localization of the process in digital agnosia in the region of the angular gyrus of the left hemisphere is determined.

The study of somatosensory gnosis for the diagnosis of somatognosia is carried out according to the following methods: 1) a test to determine the localization of touch on one, two hands, on the face; 2) discrimination test - determination of the number of touches: one or two; 3) definitions of skin-kinesthetic feeling - definition of figures, numbers, letters written on the skin on the left and right hand; (Ferster's feeling); 4) transfer of the posture of the hand and hand from one hand to another with closed eyes; 5) determination of the right and left sides of oneself and the person sitting opposite (left and right orientation); 6) the name of the fingers of the hand; 7) recognition of objects by touch with the left and right hand.

Agnosia is a pathological condition associated with a violation various kinds perception while maintaining consciousness and sensitivity. The reason for this is damage to the secondary sections of the cerebral cortex, which are responsible for the analysis and synthesis of information.

There are different types of agnosia depending on the analyzer, in the regulation of which there were violations (auditory agnosia, tactile agnosia, visual agnosia, olfactory agnosia, spatial agnosia, and others).

This condition is diagnosed during a neurological examination.

Treatment of agnosia consists in the treatment of the underlying disease.

Causes of agnosia

Agnosia is caused by damage to the projection-associative sections of the cerebral cortex, which are part of the cortical level of the analyzer systems.

In this case, a person retains elementary sensitivity, but the ability to analyze and synthesize information coming from the analyzer is lost, which results in a violation of one or another type of perception.

Damage to the cerebral cortex can be caused by: cerebral circulation, Alzheimer's disease, toxic encephalopathy, subacute sclerosing panencephalitis.

Types of agnosia

There are the following types of agnosia:

Visual agnosia - occurs when the occipital cortex is damaged. In this case, a person does not lose visual acuity, but at the same time he cannot recognize objects, distinguish signs of objects.

Visual agnosia, in turn, is divided into:

• object - there is a violation of the recognition of objects while maintaining the function of vision. Patients describe individual signs of objects, but cannot determine which object is in front of them;
• simultaneous - there is a functional narrowing of the visual field to one object. Patients perceive only one semantic unit at a time;
• agnosia on faces (prosopagnosia) - the process of recognizing familiar faces is disrupted. Patients distinguish between a face, as a whole object, and its parts, but cannot tell who is in front of them;
• color agnosia, that is, the inability to determine whether a color belongs to a particular object or to select the same colors;
• agnosia caused by opto-motor disorders, that is, the inability to direct the gaze in the necessary direction while maintaining the function of eye movement. The patient finds it difficult to fix his gaze on a given object, it is difficult for him to read;
• the weakness of optical representations is the inability to represent an object, as well as to describe its properties.

Auditory agnosia - develops with damage to the temporal cortex. If the left side is affected, then there is a violation of the discrimination of speech sounds, which leads to a speech disorder. If the right side is affected, then the patient does not recognize the noises and sounds familiar to him, or amusia develops when the ear for music disappears. In this regard, there are:

• simple auditory agnosia - the inability to identify simple sounds and noises - the rustle of paper, knocking, gurgling, ringing coins;
• auditory speech agnosia - the inability to recognize speech, which is perceived by the patient as a set of sounds unfamiliar to him;
• tonal agnosia - the inability to distinguish the expressive aspects of the voice. Patients do not catch the tone, timbre, emotional coloring of the voice. But they do understand speech.

Tactile agnosia develops when the central gyrus located in the back of the cortex is damaged. Tactile agnosia is manifested by a lack of recognition of objects by touch (with closed eyes) or a lack of recognition of the texture of an object. In this regard, object tactile agnosia and tactile texture agnosia are distinguished.

Spatial agnosia is the inability to determine various spatial parameters. Stands out:

• topographical orientation disorder - inability to navigate in a familiar place. The patient cannot find his home, is lost in his apartment, but his memory is preserved;
• depth agnosia - the inability to correctly localize objects in space, to determine the parameters closer - farther;
• unilateral spatial agnosia - a violation in which one half of the space falls out, more often the left;
• violation of stereoscopic vision;

Somatoagnosia is a violation of the recognition of parts of your body, the inability to assess their location relative to each other. These include: anosognosia (unawareness of one's own illness) and autotopagnosia (unrecognition of individual parts of the body and a violation of their perception in space).

Impaired perception of movement and time - the patient has an incorrect perception of the movement of objects and the passage of time.

They also distinguish olfactory, gustatory, digital agnosia.

Diagnosis of agnosia

The diagnosis of agnosia is based on the history (trauma, stroke, tumor) and clinical picture illness. Special tests are also carried out to establish the type of agnosia.

The patient is asked to identify simple objects using various senses. If the doctor suspects the denial of half of the space, then he asks the patient to identify the paralyzed parts of his body, or objects in different parts of the space.

Conducting a neuropsychological examination helps to establish the presence of more complex types of agnosia.

Brain imaging methods (MRI or CT) are also used to establish the nature of central lesions (hemorrhage, infarction, volumetric intracranial process), to identify areas of cortical atrophy.

To identify the primary violations of certain types of sensitivity, a physical examination is performed.

Treatment of agnosia

specific treatment for this pathological condition does not exist. Its treatment is reduced to the treatment of the underlying disease, which led to the defeat of certain areas of the cerebral cortex. Great importance at the same time, he has a consultation with a neuropsychologist, which can help the patient adapt to his defect and compensate for it at least partially.

In some cases, agnosia can resolve spontaneously. In the presence of irreversible changes in the brain, patients are forced to live with their disorder throughout their lives.

Defectologists are engaged in the correction of this disorder.

Rehabilitation with the help of an occupational therapist or speech therapist can help the patient achieve compensation for the disease.

Whether recovery occurs and how complete it will be is determined by the size and location of lesions in the brain, the degree of brain damage and the age of the patient.

Most often, recovery occurs within a period of three months to one year.

Thus, agnosia is not an independent disease, but a certain symptom complex indicating a lesion of one or another secondary part of the cerebral cortex. This state is not treated, only the underlying disease that caused agnosia is treated, the degree, the success of which depends on the prognosis for the restoration of lost perceptual functions.

Auditory agnosia is subdivided into subdominant and dominant.

Subdominant auditory agnosia is manifested in the inability to master the meaning of non-speech noises, namely a) natural, those emitted by objects of nature, b) objective, those emitted by sounding objects

Non-speech auditory agnosia occurs when the right temporal lobe is affected. In this case, children do not distinguish between sounds such as squeaks, knocks, claps, rustles, beeps, wind, rain, etc. They do not hear the voices of animals and therefore do not imitate them

Sometimes patients have an increased sensitivity to noise (hyperacusia). There are also cases of changes in the intonation-melodic side of speech, voice, elements of dysarthria. With damage to the right hemisphere, such non-verbal auditory functions as distinguishing the duration of sounds, perception of the timbre of a sound, and the ability to localize sounds in space also suffer. The ability to recognize the voices of familiar people is also impaired, especially on the telephone, on the radio.

Dominant auditory agnosia occurs with lesions located in the left hemisphere of the brain. It is speech and manifests itself in difficulties in understanding speech. At the same time, partial understanding of speech is sometimes possible, which is achieved by relying on the length of the phrase, intonation, the situation of communication, i.e. to what, according to modern ideas, is within the “competence” of the right hemisphere of the brain. With foci located in the right temple, the patient, trying to understand the statement perceived by ear, primarily relies on the sound, phonemic composition of the word, and as a result of the phonological analysis, he understands the objective meanings of words. Difficulties in decoding the prosodic characteristics of an utterance, characteristic of the pathology of the right hemisphere of the brain, limit the amount of understanding of the text perceived by ear, but do not completely eliminate it. Only bilateral foci lead to gross speech auditory agnosia.

A.R. Luria showed that when the upper temporal cortex is damaged, a syndrome of sensory (acoustic-gnostic) aphasia occurs, the description of which will be given below, and damage to the middle-temporal sections of the left temporal lobe leads to acoustic-mnestic aphasia.

Speech auditory agnosia is the most complex manifestation of auditory agnosia. Speech perception is carried out due to the joint activity of two temporal areas of the brain (right and left). Unilateral lesions of the temporal lobe, as a rule, do not cause complete auditory agnosia.

Chapter 8. Sensory and Gnostic Visual Disorders.

Visual agnosia

General principles of operation of analyzer systems

We turn to that part of the section that is devoted to the neuropsychological analysis of sensory and gnostic disorders that occur when different levels of the main analyzer systems are affected.

In all the chapters of this section, we will briefly dwell on the basic principles of the structure of each analyzer and consider the contribution of each of the levels of one or another analyzer system to the brain organization of higher mental functions.

Human analyzer systems are complex multilevel formations aimed at analyzing signals of a certain modality.

It is possible to identify several general principles structures of all analyzer systems:

a) the principle of parallel multi-channel processing of information, according to which information about different signal parameters is simultaneously transmitted through various channels of the analyzer system;

b) the principle of information analysis using neuron detectors, aimed at highlighting both relatively elementary and complex, complex characteristics of the signal, which is provided by different receptive fields;

in) the principle of sequential complication of information processing from level to level, according to which each of them performs its own analyzer functions;

G) topical principle("dot to dot") representation of peripheral receptors in the primary field of the analyzer system;

From the works of A. R. Luria

Modern ideas about the structure of mental processes come from the model of a reflex ring, or a complex self-regulating system, eachwhose link includes bothafferent components, and which as a whole has the character of a complex and active mental activity.

e) the principle of a holistic integrative representation of a signal in the central nervous system in conjunction with other signals, which is achieved due to the existence of a general model (scheme) of signals of a given modality (similar to the "spherical model of color vision").

As is known, the work of analyzer systems is studied by many disciplines, primarily neurophysiology. The neuropsychological aspect of the study of this problem is special, it is the analysis of neuropsychological symptoms that occur when different levels of the analyzer system are affected, and the construction of general theoretical ideas about the operation of the entire system as a whole. In the neuropsychological study of the work of analyzer systems, one should distinguish between two types of disorder:

1) relatively elementary sensory disorders in the form of violations of various types of sensations(sensations of light, color sensations, sensations of height, loudness, sound duration, etc.);

2) more complex gnostic disorders in the form of disorders different types perception(perception of the shape of an object, spatial relationships, symbols, speech sounds, etc.).

The first type of disorders is associated with damage to the peripheral and subcortical levels of the analyzer systems, as well as the primary cortical field of the corresponding analyzer.

The second type of disorders is primarily due to damage to the secondary cortical fields, although many other cortical and subcortical structures, including the prefrontal sections of the cerebral cortex, also take part in the brain organization of gnostic activity.

From worksA. ft, Luria

It is known that sensation includes motor components, and modern psychology considers sensation, and even more so perception, as a reflex act containing both afferent and efferent links (A. N. Leontiev,1959). To be convinced of the complex active nature of sensations, it is enough to recall that even in animals they include the process of selecting biologically significant features, and in humans they also include the active coding influence of language (J. Bruner,1957; L. A. Lyublinskaya,1969).

The active nature of the processes appears even more clearly in complex objective perception. It is well known that object perception is not only polyreceptor in nature, relying on the joint work of a whole group of analyzers, but always includes active motor components in its composition. The decisive role of eye movements in visual perception was noted by I. M. Sechenov (1874-1878), but this was proved only recently. In a number of psychophysiological studies, it was shown that the fixed eye practically cannot perceive an image consisting of many components, and that complex object perception involves active, searching eye movements that highlight the necessary features (A. L. Yarbus,1965, 1967), and only gradually, as it develops, takes on a curtailed character (A. V. Zaporozhets,1967; 3. P. Zinchenko et al.,1962).

All these facts convince us that perception is carried out with the joint participation of all functional blocks of the brain, of which the first provides the necessary tone of the cortex, the second carries out the analysis and synthesis of incoming information, and the third provides directed search movements, thereby creating an active nature of perceiving activity.

Gnostic disorders that occur with cortical lesions are called agnosia. Depending on the affected analyzer, there are visual, auditory and tactile agnosia 1 .

visual analyzer. Sensory visual disorders

Man, like all primates, belongs to the "visual" mammals; he receives basic information about the outside world through visual channels. Therefore, the role of the visual analyzer for the mental functions of a person can hardly be overestimated.

The visual analyzer, like all analyzer systems, is organized according to a hierarchical principle. The main levels of the visual system of each hemisphere are: the retina (peripheral level); optic nerve (II pair); area of ​​intersection of the optic nerves (chiasm); optic cord (the exit point of the visual pathway from the chiasm region); external or lateral geniculate body (NKT or LKT); a pillow of a visual hillock where some fibers of a visual way come to an end; the path from the lateral geniculate body to the cortex (visual radiance) and the primary 17th field of the cerebral cortex (Fig. 19, A, B, W rice. twenty; color sticker). The work of the visual system is provided by II, III, IV and VI pairs of cranial nerves.

The defeat of each of the listed levels, or links, of the visual system is characterized by special visual symptoms, special visual impairments.

The first level of the visual system- retina- is a very complex organ, which is called "a piece of the brain, taken out."

The receptor structure of the retina contains two types of receptors:

♦ cones(device for daytime, photopic vision);

♦ sticks(device of twilight, scotopic vision).

When light reaches the eye, the photopic response generated in these elements is converted into impulses transmitted through various levels visual system into the primary visual cortex (field 17). The number of cones and rods is unevenly distributed in different areas of the retina; there are significantly more cones in the central part of the retina ( fovea) - clear vision zone.

This zone is slightly shifted away from the exit point. optic nerve- an area called blind spot(papilla n. optici).

Man is one of the so-called frontal mammals, that is, animals whose eyes are located in the frontal plane. As a result, the visual fields of both eyes (that is, that part of the visual environment that is perceived by each retina separately) overlap. This overlapping of the visual fields is a very important evolutionary acquisition that allowed man to perform precise hand manipulations under visual control, as well as providing accuracy and depth of vision (binocular vision). Thanks to binocular vision, it became possible to combine the images of an object that appear in the retinas of both eyes, which dramatically improved the perception of the depth of the image, its spatial features.

The overlap zone of the visual fields of both eyes is approximately 120°. The monocular vision zone is about 30° for each eye; we see this zone with only one eye, if we fix the central point of the visual field common to both eyes.

Visual information perceived by two eyes or only by one eye (left or right) is projected onto different parts of the retina and, therefore, enters different parts of the visual system.

In general, the areas of the retina located to the nose from the midline (nosal regions) are involved in the mechanisms of binocular vision, and the regions located in the temporal regions (temporal regions) are involved in monocular vision.

In addition, it is important to remember that the retina is also organized according to the upper-lower principle: its upper and lower sections are represented differently at different levels of the visual system. Knowledge of these features of the structure of the retina makes it possible to diagnose its diseases (Fig. 21; color insert).

Damage to the retinal level of the visual system is diverse: it is different forms retinal degeneration; hemorrhages; various eye diseases in which the retina is also affected (the central place among these lesions is occupied by such a common disease as glaucoma). In all these cases, the lesion is usually unilateral, that is, vision is impaired in only one eye; further - this is a relatively elementary disorder of visual acuity (i.e., visual acuity), or visual fields (like scotoma), or color perception. Visual functions of the second eye remain intact.

The second level of the visual system- optic nerves(II pair). They are very short and located at the back. eyeballs in the anterior cranial fossa, on the basal surface of the cerebral hemispheres. Different fibers of the optic nerves carry visual information from different parts of the retinas. Fibers from the inner sections of the retinas pass in the inner part of the optic nerve, from the outer sections - in the outer, from the upper sections - in the upper, and from the lower - in the lower. Lesions of the optic nerve are encountered in the clinic of local brain lesions quite often due to various pathological processes in the anterior cranial fossa: tumors, hemorrhages, inflammatory processes, etc. Such damage to the optic nerve leads to a disorder of sensory visual functions in only one eye, and depending on the visual functions of the corresponding parts of the retina suffer from the site of the lesion. An important symptom of damage to the optic nerve is swelling of the beginning (nipple) of the optic nerve (left or right), which can lead to its atrophy.

Chiasma region is the third link in the visual system. As you know, in a person in the chiasm zone, an incomplete decussation of the visual pathways occurs. Fibers from the nasal halves of the retinas enter the opposite (contralateral) hemisphere, while fibers from the temporal halves enter the ipsilateral one. Due to the incomplete decussation of the visual pathways, visual information from each eye enters both hemispheres. It is important to remember that the fibers coming from the upper parts of the retinas of both eyes form the upper half of the chiasma, and those coming from the lower parts form the lower; fibers from the fovea also undergo partial decussation and are located in the center of the chiasm. When the chiasm is damaged, various (often symmetrical) visual field disturbances of both eyes (hemianopsia) occur due to damage to the corresponding fibers coming from the retinas. The defeat of different parts of the chiasm leads to the appearance of different types hemianopsia:

♦ bitemporal;

♦ binosal;

♦ upper quadrant;

♦ lower quadrant;

♦ unilateral nosal hemianopsia (with the destruction of the outer part of the chiasm on one side).

Hemianopsia may be complete or partial; in the latter case, scotomas (partial prolapse) occur in the corresponding parts of the visual fields. All of the listed types of hemianopsia are characteristic only for damage to the chiasmal level of the visual system.(Fig. 19; color insert).

With the defeat of the optic cords (fractes opticus), connecting the chiasm region with the external geniculate body, there is homonymous(one-sided) hemianopsia, the side of which is determined by the side of defeat. Homonymous hemianopia may be complete or incomplete. A feature of this type of hemianopsia is that, due to damage to the fibers coming from the fovea, the border between the affected and intact fields of vision runs in the form of a vertical line.

The fourth level of the visual system- external or lateral geniculate body(NKT or LKT). This part of the thalamic nucleus, the most important of the thalamic nuclei, is a large formation, consisting of nerve cells where the second neuron of the visual pathway is concentrated (the first neuron is in the retina). Thus, visual information without any processing comes directly from the retina to the LNT. A person has 80 % of the visual pathways coming from the retina end in the LNT, the remaining 20% ​​go to other formations (cushion of the thalamus, anterior colliculus, brainstem), which indicates a high level of corticalization of visual functions.

The NT, like the retina, is characterized topical structure, i.e. various areas retinas correspond to different groups of nerve cells in the NKT. In addition, in different parts of the NKT, there are areas of the visual field that are perceived by one eye (monocular vision zones), and areas that are perceived by two eyes (binocular vision zones), as well as an area of ​​central vision. With a complete lesion of the tubing, a complete unilateral hemianopsia (left-sided or right-sided) occurs, with a partial lesion - incomplete, with a border in the form of a vertical line.

In the case when the lesion is located near the NKT and irritates it, sometimes complex syndromes occur in the form of visual hallucinations associated with impaired consciousness.

As mentioned above, in addition to the NCT, there are other instances where visual information enters - this thalamus, anterior colliculus, and brainstem. When they are damaged, no disturbances of visual functions as such occur, which indicates their other purpose. The anterior colliculus is known to regulate a number of motor reflexes (such as start reflexes), including those that are “triggered” by visual information. Apparently, the cushion of the thalamus, associated with a large number of instances, in particular, with the region of the basal ganglia, also performs similar functions. The brain stem structures are involved in the regulation of the general nonspecific activation of the brain through collaterals coming from the visual pathways. Thus, visual information going to the brain stem is one of the sources supporting the activity of the nonspecific system (see Chapter 3).

The fifth level of the visual system - visual radiance(Graziole's bundle) is a rather extended part of the brain, located in the depths of the parietal and occipital lobes. This is a wide, space-occupying fan of fibers that carry visual information from different parts of the retina to different areas of the 17th field of the cortex. This area of ​​the brain is affected very often (with hemorrhages, tumors, injuries, etc.), which leads to homonymous hemianopia, i.e. loss of visual fields (left or right). Due to the wide divergence of the fibers in the Graziola bundle, homonymous hemianopsia is often incomplete, that is, blindness does not extend to the entire left (or right) half of the visual field. Last resort- primary 17th field of the cerebral cortex, It is located mainly on the medial surface of the brain in the form of a triangle, which is directed deep into the brain with an edge. This is a significant area of ​​the cerebral cortex in comparison with the primary cortical fields of other analyzers, which reflects the role of vision in human life. The most important anatomical feature of the 17th field is the good development of the IV layer of the cortex, where visual afferent impulses come; Layer IV is connected to layer V, from where local motor reflexes are “launched”, which characterizes the “primary neural complex of the cortex” ( G. I. Polyakov, 1965).

17th field organized by topical principle, i.e., different areas of the retina are represented in its different parts. This field has two coordinates: top-bottom and front-back. The upper part of the 17th field is connected with the upper part of the retina, i.e. with the lower fields of vision; the lower part of the 17th field receives impulses from the lower parts of the retina, i.e. from the upper fields of vision.

In the back of the 17th field, binocular vision is represented; in the anterior part, peripheral monocular vision.

With the defeat of the 17th field in the left and right hemispheres at the same time (which can be, for example, with injuries of the occipital pole), central blindness. When the lesion captures the 17th field of one hemisphere, there is a loss of visual fields on one side, and with a right-sided focus, a “fixed” left-sided hemianopsia is possible, when the patient does not seem to notice his visual defect. With the defeat of the 17th field, the border between the “good” and “bad” parts of the visual fields does not pass in the form of a vertical line, but in the form of a semicircle in the fovea zone, since this preserves the central vision area, which in humans is represented in both hemispheres, which defines the contour of the boundary line. This feature makes it possible to distinguish cortical and subcortical hemianopsia(Fig. 19; color insert).

As a rule, patients have not a complete, but only a partial lesion of the 17th field, which leads to a partial loss of visual fields (scotomas); while the areas of impaired visual fields are symmetrical in shape and size in both eyes. With less severe lesions of the 17th field, partial disturbances of visual functions occur in the form of a decrease (change) in color perception, photopsy (i.e., a sensation of bright flashes, "sparks", sometimes colored, appearing in a certain part of the visual field). All the visual dysfunctions described above are sensory, relatively elementary disorders that are not directly related to higher visual functions, although they are their basis.

Gnostic visual disorders

Higher gnostic visual functions are provided primarily by the work of the secondary fields of the visual system (18th and 19th) and the tertiary fields of the cerebral cortex adjacent to them. The secondary 18th and 19th fields are located both on the outer convexital and on the inner medial surfaces of the cerebral hemispheres. They are characterized by a well-developed layer III, in which impulses are switched from one area of ​​the cortex to another.

With electrical stimulation of the 18th and 19th fields, not local, point excitation occurs, as with stimulation of the 17th field, but activation of a wide zone, which indicates wide associative connections of these areas of the cortex.

From studies carried out on humans by W. Penfield, G. Jasper (1959) and a number of other authors, it is known that with electrical stimulation of the 18th and 19th fields, complex visual images appear. These are no longer separate flashes of light, but familiar faces, pictures, sometimes some vague images. Basic information about the role of these areas of the cerebral cortex in visual functions was obtained from the clinic of local brain lesions. Clinical observations show that the defeat of these areas of the cortex and the subcortical zones adjacent to them ("the nearest subcortex", in the words of A.R. Luria) leads to various disorders of visual gnosis. These violations are called visual agnosia. This term refers to disorders of visual perception that occur when the cortical structures of the posterior parts of the cerebral hemispheres are damaged and proceed with the relative preservation of elementary visual functions (visual acuity, visual fields, color perception). In all forms of agnostic visual disorders, elementary sensory visual functions remain relatively intact, i.e., patients see well enough, they have normal color perception, and visual fields are often preserved; in other words, they seem to have all the prerequisites to perceive objects correctly. However, it is precisely the gnostic level of the visual system that is disturbed in them. In some cases, patients, in addition to gnostic, have violations of sensory functions. But these are, as a rule, relatively subtle defects that cannot explain the severity and nature of violations of higher visual functions.

The first description of visual agnosia belongs to G. Munch (1881), who, working with dogs with lesions in the occipital lobes of the brain, found that "the dog sees, but does not understand" what he sees; the dog seems to see objects (because he does not bump into them), but "does not understand" their meaning.

Naturally, in humans, violations of visual functions are much more complicated. In the clinic of local brain lesions, various forms of violations of higher visual functions, or various forms of visual agnosia, are described. The term "agnosia" was first used by 3. Freud (1891), who was not only the founder of psychoanalysis, but also the largest neurologist who studied the functions nervous system. The cases of violations of higher visual functions described by him were designated as "visual agnosia". After 3. Freud, many authors were engaged in the study of visual agnosia; it can be said that of all violations mental processes, which are observed in local lesions of the brain, at the phenomenological level, it is visual agnosias that are best studied.

It should be noted that both domestic and foreign publications are mainly devoted to describing what happens to patients with damage to certain areas of the "wide visual sphere" - the occipital-parietal areas of the cortex, i.e., the primary study of visual dysfunctions at the phenomenological level.

The nature and structure of mental disorders in visual agnosias and their brain mechanisms are much less studied. Until now, there is no general theory explaining the occurrence of various forms of violations of higher visual functions, which directly affects the classifications of visual agnosias existing in neuropsychology and clinical neurology. All of them are based on a phenomenological distinction between types of visual dysfunctions, that is, on the knowledge of what exactly the patient does not perceive (or mistakenly perceives). Thus, at present there is no single classification of visual agnosias, since there is no single explanation of the nature of these disorders.

1) if the patient, correctly assessing the individual elements of the object (or its image), cannot understand its meaning as a whole - this is called subject agnosia;

2) if he does not distinguish between human faces (or photographs) - facial agnosia;

3) if he is poorly oriented in the spatial features of the image - optical-spatial agnosia;

4) if he, copying the letters correctly, cannot read them - letter agnosia;

5) if he distinguishes colors, but does not know which objects are colored in a given color, i.e., cannot remember the color of familiar objects, - color agnosia;

6) as an independent form stands out and simultaneous agnosia- such a violation of visual gnosis, when the patient can perceive only individual fragments of the image, and this defect is also observed with the preservation of the visual fields.

It is obvious that such a principle of distinguishing different forms of visual agnosia is very primitive; this classification lacks a single basis, which reflects the insufficient level of development of this field of knowledge.

Clinical observations show that the form of visual gnosis disorders is associated both with the side of the brain lesion and with the localization of the lesion within the "broad visual sphere" - the convexital cortex of the occipital and parietal parts of the brain, where two main subareas are distinguished: the lower and upper parts.

Let's take a closer look different forms of visual agnosia.

object agnosia- one of the most common forms of visual gnosis disorders, which, to one degree or another, occurs in most patients with lesions of the occipito-parietal regions of the brain. In a rough form, object agnosia is observed only with bilateral lesions of the occipital-parietal regions of the brain, that is, with bilateral lesions of the 18th and 19th fields.

Subject visual agnosia is associated with damage to the lower part of the "wide visual sphere". It is characterized by the fact that the patient sees as if everything, he can describe the individual features of the object, but cannot say what it is. A particularly gross violation of the ability to correctly assess an object occurs with bilateral damage to the lower parts of a wide visual sphere: the patient, looking at the object, cannot identify it, but when feeling it, he often solves this problem correctly. In their daily lives, such patients behave almost like blind people, and although they do not stumble upon objects, they constantly feel them or navigate by sounds. However, in such a crude form, object agnosia is relatively rare, more often it manifests itself in a latent form when performing special visual tasks: for example, when recognizing contour, crossed out, superimposed on each other, inverted images, etc.

So, when combining 3, 4, 5 contours (Poppelreiter's test) healthy man sees the contours of all objects; in patients, this task causes great difficulties: they cannot distinguish individual contours and see just a confusion of lines.

With object agnosia, difficulties in recognizing the shape of objects are primary, and in the most "pure" form they appear when identifying precisely the contours of objects; at the same time, copying their drawings can be safe (Fig. 22).

In patients with object agnosia (as well as with other forms of visual gnosis disorders), the temporal characteristics of visual perception roughly change. Tachistoscopy studies have established that in such patients the image recognition thresholds increase sharply; and, as a rule, they increase by several orders of magnitude. If a healthy person perceives simple images in 5-10 ms (without a background erasing image), then in patients with simple images, the recognition time for simple images increases to 1 s or more. Thus, with visual agnosia, a completely different mode of operation of the visual system is observed, which causes great difficulties in processing visual information.

Opto-spatial agnosia It is associated mainly with the defeat of the upper part of the "wide visual sphere". In a particularly rough form, it is observed with bilateral lesions of the occipito-parietal regions of the brain. However, even with a unilateral lesion, these violations are also expressed quite clearly.

With optical-spatial agnosia, patients lose the ability to orient themselves in the spatial features of the environment and images of objects. Their left-right orientation is disturbed; they cease to understand the symbolism of the drawing, which reflects the spatial features of objects. Such patients do not understand the geographical map, their orientation in the countries of the world is disturbed. A description of such a violation is devoted to the book by A. R. Luria “The Lost and Returned World” (1971), which tells about a patient, a former topographer, who was injured in the occipital-parietal region of the left hemisphere of the brain.

In severe cases, the orientation of patients is disturbed not only in the left-right, but also in the upper-lower coordinates. In patients with optical-spatial (as well as with object) agnosia, as a rule, the ability to draw is impaired (with the ability to copy an image relatively intact). They do not know how to convey the spatial features of objects in the drawing (further-closer, more-less, left-right, top-bottom). In some cases, even the general scheme of the drawing breaks up. So, patients, drawing a person, separately depict parts of his body (arms, legs, eyes, nose, etc.) and do not know how to connect them. The pattern is more often disturbed when the posterior sections of the right hemisphere are affected (Fig. 23, a, b). In some cases (as a rule, with right-hemispheric foci), there is unilateral opto-spatial agnosia, when patients, even copying the drawing, depict only one side of the object or grossly distort the image of one (often the left) side (Fig. 24).

At the same time, the possibility of visual afferentation of spatially organized movements, i.e., "postural praxis", is also often impaired. Such patients cannot copy the posture shown to them by the experimenter; do not know how to position their hand in relation to their body; they lack that immediate ease of perceiving spatial relationships that is inherent in healthy people, and this makes it difficult to copy postures from a visual model (performed with one or two hands).

Various difficulties are associated with this in everyday motor acts, in which the spatial orientation of movements is required. These patients perform poorly movements that require elementary visual-spatial orientation, for example, they cannot lay a blanket on the bed, put on a jacket, trousers, etc. Such disorders are called “dressing apraxia”. Combinations of visuospatial and motor-spatial disorders are called "apractognosia".

Optical-spatial disorders sometimes affect reading skills. In these cases, there are difficulties in reading such letters that have “left-right” signs. Patients cannot distinguish between correctly and incorrectly written letters (for example: K, M, P, Chi, etc.), and this task can be one of the tests for determination of visual orientation in the spatial features of objects. In such cases, violations of the recognition of letters with mirror spatial features, as a rule, reflect a general defect in spatial orientation in objects.

A special form of visual agnostic disorders is letter agnosia. In its purest form, letter agnosia manifests itself in the fact that patients, copying the letters quite correctly, cannot name them. Their reading skills are deteriorating (primary alexia).

Such a reading disorder occurs in isolation from other disorders of higher visual functions, which gives reason to single out this defect as an independent form of agnosia. Such patients correctly perceive objects, correctly evaluate their images, and even correctly orient themselves in complex spatial images and real objects, but they "do not understand" letters and cannot read.

This form of agnosia, as a rule, occurs with damage to the left hemisphere of the brain - the lower part of the "wide visual sphere" (in right-handers).

color agnosia also represents an independent type of visual gnostic disorders. There are actually color agnosia and a violation of the recognition of colors as such (color blindness or defects in color perception). Color blindness and impaired color perception can be of both peripheral and central origin, i.e., be associated with damage to both the retina and the subcortical and cortical parts of the visual system. It is known that color perception occurs under the action of three different types of cones (retinal detectors), which are sensitive to different colors: blue-green, red-green and yellow. This ability of cones to be reactive to certain color stimuli is the basis of color perception, and a defect in this ability can be caused by different type retinal lesions (degeneration, etc.).

There are known color discrimination disorders associated with damage to the NKT and the occipital cortex (field 17), which indicates the existence of a special channel (or channels) in the visual system designed to carry information about the color of an object.

Color agnosia, in contrast to color discrimination disorders, is a violation of higher visual functions. The clinic describes violations of color gnosis, which are observed against the background of intact color perception. Such patients correctly distinguish individual colors and correctly name them. However, it is difficult for them, for example, to correlate a color with a certain object and vice versa; they cannot remember the color of an orange, a carrot, a Christmas tree, etc. Patients cannot name objects of a certain specific color. They do not have a generalized idea of ​​color, and therefore they are not able to perform the color classification procedure, which is not due to the difficulties in distinguishing colors, but to the difficulties of categorizing them. It is known that a person perceives a huge number of shades of colors, but there are relatively few names of colors (categories). Therefore, in ordinary life a healthy person constantly solves the problem of color categorization. It is this categorization of color sensations that is difficult in patients with color agnosia.

A special form of visual agnosia is simultaneous agnosia. For a long time she was known as Balint syndrome. This form of violation of visual gnosis is manifested in the fact that the patient cannot perceive two images at the same time, since his volume of visual perception is sharply narrowed.

The patient cannot perceive the whole, he sees only its part (or parts). The question arises: why the patient cannot shift his gaze and examine the entire image sequentially? This is because Balint's syndrome is always accompanied by complex eye movement disorders called gaze ataxia.

The patient's gaze becomes uncontrollable, the eyes make involuntary jumps, constantly being in motion. This creates difficulties in organized visual search, as a result of which the patient cannot view the object sequentially. It is assumed that the cause of simultaneous agnosia is the weakness of the cortical visual cells, which are capable of only narrow-local foci of excitation. The connection of Balint's syndrome with the side of the lesion and the localization of the focus within the "wide visual sphere" has not yet been established.

facial agnosia- a special form of violations of visual gnosis, which manifests itself in the fact that the patient loses the ability to recognize real faces or their images (in photographs, drawings, etc.).

With a rough form of facial agnosia, patients cannot distinguish between female and male faces, as well as the faces of children and adults; do not recognize the faces of their relatives and friends. Such patients recognize people (including those closest to them) only by voice. Facial agnosia is clearly associated with the defeat of the posterior parts of the right hemisphere (in right-handed people), to a greater extent - the lower parts of the "wide visual sphere".

In general, the question of the relationship between different forms of visual agnostic disorders with the side and zone of damage to the occipital-parietal regions of the brain has not been finally resolved. Many authors indicate that various forms of visual agnosia manifest themselves especially clearly when the commissural fibers of the corpus callosum, connecting the 18th and 19th fields of the left and right hemispheres of the brain, are damaged.

Of particular interest for understanding the mechanisms of visual agnosia are eye movement studies(regulated III, IV and VI pairs of cranial nerves) with various forms visual disturbances. Violations of visual gnosis correlate with various disorders of oculomotor activity that accompanies the visual perception of an object. These may be phenomena of inactivity of eye movements, oculomotor perseverations (Fig. 25, BUT), ignoring one side of the visual field (Fig. 25, B) and etc.

The question of the role of eye movements in disorders of visual gnosis is debatable. According to one point of view, eye movements circling the contour of an object are an indispensable mechanism for visual perception (A L. Yarbus, 1965 and others). However, studies have shown that many forms of visual agnosia occur with intact oculomotor activity.

In the literature devoted to the problem of visual agnosias, the question of the role of the temporal parts of the brain in their origin is also discussed. According to some authors, violations of visual gnosis occur not only in the occipital-parietal foci, but also in the defeat of the lower temporal regions of the cerebral hemispheres; other authors deny these data, giving them a different explanation. All this speaks of the great complexity of the problem of the brain organization of visual perception.

In general, as clinical observations show, violations of visual gnosis are heterogeneous. The nature of agnosia apparently depends on the side of the brain lesion, and on the location of the focus within the "wide visual sphere", and on the degree of involvement in the pathological process of the commissural fibers that unite the posterior parts of the left and right hemispheres. It is important to note that different forms of visual gnosis disorders occur in isolation. This testifies about the existence of separately, autonomously functioning channels that process different types of visual information. However, it should always be remembered that different forms of visual perception are not realized only with the help of special visual channels; in all cases, the entire brain as a whole, all its three main blocks, takes part in the implementation of higher visual functions (or visual gnostic activity), as follows from the theory of systemic dynamic localization of higher mental functions. Therefore, violations of visual gnosis can occur, for example, with damage to the frontal lobes of the brain; then they have a secondary character and are denoted as pseudoagnosia.

In this way, neuropsychological data confirm the general concept that the visual system is organized as a multi-channel apparatus, simultaneously processing a variety of visual information, various "blocks"(channels) which can be affected in isolation with the safe operation of other "blocks"(channels). As a result, there may be disturbances in the perception of only objects, or faces, or colors, or letters, or spatially oriented objects. The phenomenology of visual perception disorders in local brain lesions provides important information for understanding the general principles of the structure and functioning of the visual system.