The study of the central nervous system includes a group of experimental and clinical methods. Experimental methods include cutting, extirpation, destruction of brain structures, as well as electrical stimulation and electrical coagulation. Clinical methods include electroencephalography, evoked potentials, tomography, etc.

Experimental methods

1. Cut and cut method. The method of cutting and switching off various parts of the central nervous system is done in various ways. Using this method, you can observe changes in conditioned reflex behavior.

2. Methods of cold switching off brain structures make it possible to visualize the spatio-temporal mosaic of electrical processes in the brain during the formation of a conditioned reflex in different functional states.

3. Methods of molecular biology are aimed at studying the role of DNA, RNA molecules and other biologically active substances in the formation of a conditioned reflex.

4. The stereotactic method is that an electrode is introduced into the animal’s subcortical structures, with which one can irritate, destroy, or introduce chemical substances. Thus, the animal is prepared for a chronic experiment. After the animal recovers, the conditioned reflex method is used.

Clinical methods

Clinical methods make it possible to objectively assess the sensory functions of the brain, the state of the pathways, the brain’s ability to perceive and analyze stimuli, as well as identify pathological signs of disruption of the higher functions of the cerebral cortex.

Electroencephalography

Electroencephalography is one of the most common electrophysiological methods for studying the central nervous system. Its essence lies in recording rhythmic changes in the potentials of certain areas of the cortex big brain between two active electrodes (bipolar method) or an active electrode in a certain area of ​​the cortex and a passive one, superimposed on an area remote from the brain.

An electroencephalogram is a recording curve of the total potential of the constantly changing bioelectrical activity of a significant group of nerve cells. This amount includes synaptic potentials and partly action potentials of neurons and nerve fibers. Total bioelectrical activity is recorded in the range from 1 to 50 Hz from electrodes located on the scalp. The same activity from the electrodes, but on the surface of the cerebral cortex is called an electrocorticogram. When analyzing EEG, the frequency, amplitude, shape of individual waves and the repeatability of certain groups of waves are taken into account.

Amplitude is measured as the distance from the baseline to the peak of the wave. In practice, due to the difficulty of determining the baseline, peak-to-peak amplitude measurements are used.

Frequency refers to the number of complete cycles completed by a wave in 1 second. This indicator is measured in hertz. The reciprocal of the frequency is called the period of the wave. The EEG records 4 main physiological rhythms: ά -, β -, θ -. and δ – rhythms.

α - rhythm has a frequency of 8-12 Hz, amplitude from 50 to 70 μV. It predominates in 85-95% of healthy people over nine years of age (except for those born blind) in a state of quiet wakefulness with eyes closed and is observed mainly in the occipital and parietal regions. If it dominates, then the EEG is considered synchronized.

The synchronization reaction is an increase in amplitude and a decrease in EEG frequency. The EEG synchronization mechanism is associated with the activity of the output nuclei of the thalamus. A variant of the ά-rhythm are “sleep spindles” lasting 2-8 seconds, which are observed when falling asleep and represent regular alternations of increasing and decreasing amplitude of waves in the frequencies of the ά-rhythm. Rhythms of the same frequency are:

μ – rhythm recorded in the Rolandic sulcus, having an arched or comb-shaped waveform with a frequency of 7-11 Hz and an amplitude of less than 50 μV;

κ - rhythm noted when applying electrodes in the temporal lead, having a frequency of 8-12 Hz and an amplitude of about 45 μV.

β - rhythm has a frequency from 14 to 30 Hz and a low amplitude - from 25 to 30 μV. It replaces the ά rhythm during sensory stimulation and emotional arousal. The β rhythm is most pronounced in the precentral and frontal areas and reflects a high level of functional activity of the brain. The change from ά - rhythm (slow activity) to β - rhythm (fast low-amplitude activity) is called EEG desynchronization and is explained by the activating influence on the cerebral cortex of the reticular formation of the brainstem and the limbic system.

θ – rhythm has a frequency from 3.5 to 7.5 Hz, amplitude from 5 to 200 μV. In a waking person, the θ rhythm is usually recorded in the anterior regions of the brain during prolonged emotional stress and is almost always recorded during the development of the phases of slow-wave sleep. It is clearly registered in children who are in a state of displeasure. The origin of the θ rhythm is associated with the activity of the bridge synchronizing system.

δ - rhythm has a frequency of 0.5-3.5 Hz, amplitude from 20 to 300 μV. Occasionally recorded in all areas of the brain. The appearance of this rhythm in a awake person indicates a decrease in the functional activity of the brain. Stably fixed during deep slow-wave sleep. The origin of the δ - EEG rhythm is associated with the activity of the bulbar synchronizing system.

γ - waves have a frequency of more than 30 Hz and an amplitude of about 2 μV. Localized in the precentral, frontal, temporal, parietal areas of the brain. When visually analyzing the EEG, two indicators are usually determined: the duration of the ά-rhythm and the blockade of the ά-rhythm, which is recorded when a particular stimulus is presented to the subject.

In addition, the EEG has special waves that differ from the background ones. These include: K-complex, λ - waves, μ - rhythm, spike, sharp wave.

The K complex is a combination of a slow wave with a sharp wave, followed by waves with a frequency of about 14 Hz. The K-complex occurs during sleep or spontaneously in a waking person. The maximum amplitude is observed in the vertex and usually does not exceed 200 μV.

Λ waves are monophasic positive sharp waves arising in the occipital area associated with eye movements. Their amplitude is less than 50 μV, frequency is 12-14 Hz.

Μ – rhythm – a group of arched and comb-shaped waves with a frequency of 7-11 Hz and an amplitude of less than 50 μV. They are registered in the central areas of the cortex (Roland's sulcus) and are blocked by tactile stimulation or motor activity.

A spike is a wave that clearly differs from background activity, with a pronounced peak lasting from 20 to 70 ms. Its primary component is usually negative. Spike-slow wave is a sequence of superficially negative slow waves with a frequency of 2.5-3.5 Hz, each of which is associated with a spike.

A sharp wave is a wave that differs from background activity with an emphasized peak lasting 70-200 ms.

At the slightest attraction of attention to a stimulus, desynchronization of the EEG develops, that is, a reaction of ά-rhythm blockade develops. A well-defined ά-rhythm is an indicator of the body’s rest. A stronger activation reaction is expressed not only in the blockade of the ά - rhythm, but also in the strengthening of high-frequency components of the EEG: β - and γ - activity. A decrease in the level of functional state is expressed in a decrease in the proportion of high-frequency components and an increase in the amplitude of slower rhythms - θ- and δ-oscillations.

Method for recording impulse activity of nerve cells

The impulse activity of individual neurons or a group of neurons can be assessed only in animals and, in some cases, in humans during brain surgery. To record neural impulse activity of the human brain, microelectrodes with tip diameters of 0.5-10 microns are used. They can be made of stainless steel, tungsten, platinum-iridium alloys or gold. The electrodes are inserted into the brain using special micromanipulators, which allow the electrode to be precisely positioned to the desired location. The electrical activity of an individual neuron has a certain rhythm, which naturally changes under different functional states. The electrical activity of a group of neurons has a complex structure and on a neurogram looks like the total activity of many neurons, excited at different times, differing in amplitude, frequency and phase. The received data is processed automatically using special programs.

Evoked potential method

The specific activity associated with a stimulus is called an evoked potential. In humans, this is the registration of fluctuations in electrical activity that appear on the EEG with a single stimulation of peripheral receptors (visual, auditory, tactile). In animals, afferent pathways and switching centers of afferent impulses are also irritated. Their amplitude is usually small, therefore, to effectively isolate evoked potentials, the technique of computer summation and averaging of EEG sections that was recorded during repeated presentation of the stimulus is used. The evoked potential consists of a sequence of negative and positive deviations from the baseline and lasts about 300 ms after the end of the stimulus. The amplitude and latency period of the evoked potential are determined. Some of the components of the evoked potential, which reflect the entry of afferent excitations into the cortex through specific nuclei of the thalamus, and have a short latent period, are called the primary response. They are registered in the cortical projection zones of certain peripheral receptor zones. Later components that enter the cortex through the brainstem reticular formation, nonspecific nuclei of the thalamus and limbic system and have a longer latency period are called secondary responses. Secondary responses, unlike primary ones, are recorded not only in the primary projection zones, but also in other areas of the brain, connected by horizontal and vertical nerve pathways. The same evoked potential can be caused by many psychological processes, and the same mental processes can be associated with different evoked potentials.

Tomographic methods

Tomography is based on obtaining images of brain slices using special techniques. The idea of ​​this method was proposed by J. Rawdon in 1927, who showed that the structure of an object can be reconstructed from the totality of its projections, and the object itself can be described by many of its projections.

Computed tomography is a modern method that allows you to visualize the structural features of the human brain using a computer and an X-ray machine. In a CT scan, a thin beam of X-rays is passed through the brain, the source of which rotates around the head in a given plane; The radiation passing through the skull is measured by a scintillation counter. In this way, X-ray images of each part of the brain are obtained from different points. Then, using a computer program, these data are used to calculate the radiation density of the tissue at each point of the plane under study. The result is a high-contrast image of a brain slice in a given plane. Positron emission tomography is a method that allows you to evaluate metabolic activity in various parts of the brain. The test subject ingests a radioactive compound, which makes it possible to trace changes in blood flow in a particular part of the brain, which indirectly indicates the level of metabolic activity in it. The essence of the method is that each positron emitted by a radioactive compound collides with an electron; in this case, both particles mutually annihilate with the emission of two γ-rays at an angle of 180°. These are detected by photodetectors located around the head, and their registration occurs only when two detectors located opposite each other are excited simultaneously. Based on the data obtained, an image is constructed in the appropriate plane, which reflects the radioactivity of different parts of the studied volume of brain tissue.

The nuclear magnetic resonance (NMR) method allows you to visualize the structure of the brain without the use of X-rays and radioactive compounds. A very strong magnetic field is created around the subject's head, which affects the nuclei of hydrogen atoms, which have internal rotation. Under normal conditions, the rotation axes of each core have a random direction. In a magnetic field, they change orientation in accordance with the lines of force of this field. Turning off the field leads to the fact that the atoms lose the uniform direction of the axes of rotation and, as a result, emit energy. This energy is recorded by a sensor, and the information is transmitted to a computer. Impact Cycle magnetic field is repeated many times and as a result, a layer-by-layer image of the subject’s brain is created on the computer.

Rheoencephalography

Rheoencephalography is a method for studying the blood circulation of the human brain, based on recording changes in the resistance of brain tissue to high-frequency alternating current depending on the blood supply and allows one to indirectly judge the amount of total blood supply to the brain, the tone, elasticity of its vessels and the state of venous outflow.

Echoencephalography

The method is based on the property of ultrasound to be reflected differently from brain structures, cerebrospinal fluid, skull bones, and pathological formations. In addition to determining the size of the localization of certain brain formations, this method allows you to estimate the speed and direction of blood flow.

Study of the functional state of the vegetative nervous system person

The study of the functional state of the ANS is of great diagnostic importance in clinical practice. The tone of the ANS is judged by the state of reflexes, as well as by the results of a number of special functional tests. Methods for clinical research of VNS are conditionally divided into the following groups:

Patient interview;

Study of dermographism (white, red, elevated, reflex);

Study of vegetative pain points;

Cardiovascular tests (capillaroscopy, adrenaline and histamine skin tests, oscillography, plethysmography, determination of skin temperature, etc.);

Electrophysiological tests – study of electro-skin resistance using a direct current apparatus;

Determination of the content of biologically active substances, for example catecholamines in urine and blood, determination of blood cholinesterase activity.

There are the following methods for studying the functions of the central nervous system:

1. Method of cutting the brain stem at various levels. For example, between the medulla oblongata and the spinal cord.

2. Method of extirpation (removal) or destruction of parts of the brain.

3. Method of irritating various parts and centers of the brain.

4. Anatomical and clinical method. Clinical observations of changes in the functions of the central nervous system when any of its parts are affected, followed by a pathological examination.

5. Electrophysiological methods:

A. electroencephalography - registration of brain biopotentials from the surface of the scalp. The technique was developed and introduced into the clinic by G. Berger.

b. registration of biopotentials of various nerve centers; used in conjunction with stereotactic technique, in which electrodes are inserted into a strictly defined nucleus using micromanipulators.

V. evoked potential method, recording the electrical activity of brain areas during electrical stimulation of peripheral receptors or other areas;

6. method of intracerebral administration of substances using microinophoresis;

7. chronoreflexometry - determination of reflex time.

End of work -

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Chewing
Chewing serves for mechanical processing of food, i.e. its biting, crushing, grinding. When chewing, food is moistened with saliva, and a food bolus is formed from it. Chewing occurs thanks to

Swallowing
Swallowing is a complex reflex act that begins voluntarily. The formed food bolus moves to the back of the tongue, the tongue is pressed against the hard palate and moves to the root of the tongue. Here

Composition and properties of gastric juice. The meaning of its components
1.5 - 2.5 liters of juice are produced per day. Outside of digestion, only 10 - 15 ml of juice is released per hour. This juice has a neutral reaction and consists of water, mucin and electrolytes. When eating

Regulation of gastric secretion
Digestive secretion is regulated through neurohumoral mechanisms. There are three phases in it: complex reflex, gastric and intestinal. Compound reflex is divided into conditioned reflex

The role of the pancreas in digestion
Food entering the duodenum is exposed to pancreatic, intestinal juices and bile. Pancreatic juice is produced by exocrine cells of the pancreas. This

Mechanisms of production and regulation of pancreatic juice secretion
Proenzymes and pancreatic enzymes are synthesized by the ribosomes of acinar cells and stored in them in the form of granules. During digestion, they are secreted into the acinar ducts and diluted in them

Liver functions. The role of the liver in digestion
Of all organs, the liver plays a leading role in the metabolism of proteins, fats, carbohydrates, vitamins, hormones and other substances. Its main functions: 1. Antitoxic. It neutralizes toxic

The importance of the small intestine. Composition and properties of intestinal juice
Intestinal juice is a product of Brunner's, Lieberkühn's glands and enterocytes of the small intestine. The glands produce the liquid part of the juice containing minerals and mucin. Juice enzymes isolated

Cavity and parietal digestion
Digestion in the small intestine is carried out using two mechanisms: cavity and parietal hydrolysis. During cavity digestion, enzymes act on substrates located in the intestinal cavity

Functions of the large intestine
Final digestion occurs in the large intestine. Its glandular cells secrete a small amount of alkaline juice, with pH = 8.0-9.0. The juice consists of a liquid part and mucous lumps. Liquid

Motor function of the small and large intestines
Intestinal contractions are provided by smooth muscle cells that form longitudinal and circular layers. Due to the connections between cells, intestinal smooth muscles are a functional syncytium

Mechanisms of absorption of substances in the digestive canal
Absorption is the process of transferring the final products of hydrolysis from the digestive canal into the intercellular fluid, lymph and blood. It mainly occurs in the small intestine. Its length is

Food motivation
Food consumption by the body occurs in accordance with the intensity of nutritional needs, which is determined by its energy and plastic costs. This regulation of food intake is

Nutrients
The constant exchange of substances and energy between the organism and the environment is a necessary condition for its existence and reflects their unity. The essence of this exchange is that

Methods for measuring the body's energy balance
The ratio between the amount of energy received from food and the energy released into the external environment is called the energy balance of the body. There are 2 methods for determining the excreted organism

BX
The amount of energy expended by the body to perform vital functions important functions, is called the basal metabolic rate (BM). This is the expenditure of energy to maintain a constant body temperature, work

Physiological basis of nutrition. Power modes
Depending on age, gender and profession, the consumption of proteins, fats and carbohydrates should be: M groups I-IV

Exchange of water and minerals
The water content in the body is on average 73%. The body's water balance is maintained by equalizing the water consumed and excreted. The daily need for it is 20-40 ml/kg of weight. With liquids

Regulation of metabolism and energy
The highest centers for the regulation of energy metabolism and metabolism are located in the hypothalamus. They influence these processes through the autonomic nervous and hypothalamic-pituitary systems. Sympathetic department

Thermoregulation
Phylogenetically, two types of body temperature regulation have emerged. In cold-blooded or poikilothermic organisms, the metabolic rate is low. Therefore, heat production is low. They are incapable of

Kidney functions. Mechanisms of urine formation
The renal parenchyma contains the cortex and medulla. The structural unit of the kidney is the nephron. Each kidney has about a million nephrons. Each nephron consists of a vascular glomerulus, located

Regulation of urine formation
The kidneys have a high ability for self-regulation. The lower the osmotic pressure of the blood, the more pronounced the filtration processes and the weaker the reabsorption and vice versa. Nervous regulation is carried out through

Non-excretory functions of the kidneys
1. Regulation of the constancy of the ionic composition and volume of the intercellular fluid of the body. The basic mechanism for regulating blood volume and intercellular fluid is a change in sodium content. When increasing

Urinary excretion
Urine is constantly produced in the kidneys and flows through the collecting ducts into the pelvis, and then through the ureters into the bladder. The filling rate of the bladder is about 50 ml/hour. At this time, called p

Skin functions
The skin performs the following functions: 1.Protective. It protects the tissues, blood vessels, and nerve fibers located underneath it. 2.Thermoregulatory. Provided through thermal radiation, conv

Types V.N.D

Speech functions of the hemispheres
The interaction of the organism with the external environment is carried out through stimuli or signals. Depending on the nature of the signals acting on the body, I.P. Pavlov identified two

Congenital forms of behavior. Unconditioned reflexes
Unconditioned reflexes are the body’s innate responses to stimulation. Properties unconditioned reflexes: 1. They are innate, i.e. inherited 2. Inherited by everyone

Conditioned reflexes, mechanisms of formation, meaning
Conditioned reflexes (C.R.) are individually acquired reactions of the body to irritation in the process of life. The creator of the doctrine of conditioned reflexes I.P. Pavlov called them temporary connections

Unconditioned and conditioned inhibition
Studying the patterns of V.N.D. I.P. Pavlov established that there are 2 types of inhibition of conditioned reflexes: external or unconditional and internal or conditioned. External inhibition is an emergency process

Dynamic stereotype
All signals coming from the external environment are analyzed and synthesized. Analysis is differentiation, i.e. signal discrimination. Unconditioned reflex analysis begins in the receptors themselves and

Structure of a behavioral act
Behavior is a complex of external interrelated reactions that are carried out by the body to adapt to changing environmental conditions. The structure of behavior was most simply described

Memory and its importance in the formation of adaptive reactions
Learning and memory are of great importance for individual behavior. There are genotypic or innate memory and phenotypic, i.e. acquired memory. Genotypic memory is

Physiology of emotions
Emotions are mental reactions that reflect the subjective attitude of an individual to objective phenomena. Emotions arise as part of motivations and play an important role in shaping behavior. Allocate 3 in

Stress, its physiological significance
The functional state is the level of activity of the body at which one or another of its activities is performed. The lower levels of F.S. - coma, then sleep. Higher aggressive-defensive

Dream theories
Sleep is a long-term functional state characterized by a significant decrease in neuropsychic and motor activity, which is necessary to restore the brain's ability to

Theories of sleep mechanisms
1. Chemical theory of sleep. Proposed in the last century. It was believed that during wakefulness, hypnotoxins are formed, which induce sleep. It was subsequently rejected. However, now you are again

Types V.N.D
Based on the study of conditioned reflexes and assessment of the external behavior of animals, I.P. Pavlov identified 4 types of V.N.D. He based his classification on 3 indicators of excitation processes

Functions of the hemispheres
According to I.P. According to Pavlov, the interaction of the organism with the external environment is carried out through stimuli or signals. Depending on the nature of the signals acting on the body, he identified two signals:

Thinking and consciousness
Thinking is a process of human cognitive activity, manifested by a generalized reflection of phenomena outside world and your inner experiences. The essence of thinking is the ability to mentally

Unconditioned reflex, conditioned reflex, humoral mechanisms of regulation of sexual functions
Sexual behavior plays a special role in various forms of behavior. It is necessary for the conservation and distribution of the species. Sexual behavior is completely described by P.K. Anokhina.

Adaptation, its types and periods
Adaptation is the adaptation of the structure, functions of organs and the body as a whole, as well as the population of living beings to changes environment. There are genotypic and phenotypic adaptation. Basically

Physiological basis of labor activity
Labor physiology is an applied branch of human physiology and studies the physiological phenomena that accompany various types of physical and mental labor. Mental

Biorhythms
Biorhythms are called cyclic changes in the functions of organs, systems and the body as a whole. The main characteristic cyclical activity is its periodicity, i.e. time for koto

Periods of human ontogenesis
The following periods of human ontogenesis are distinguished: Antenatal ontogenesis: 1. Germinal or embryonic period. The first week after conception. 2.Embryonic

Development of the neuromuscular system of children
Newborns anatomically have all skeletal muscles. The number of muscle fibers does not increase with age. The growth of muscle mass occurs due to an increase in the size of myofibrils. They

Indicators of strength, work and endurance of muscles during development
With age, the strength of muscle contractions increases. This is explained not only by an increase in the length and diameter of myocytes, an increase in total muscle mass, but also by an improvement in motor reflexes. Nap

Physicochemical properties of children's blood
The relative amount of blood decreases as we get older. In newborns it makes up 15% of body weight. For 11 year olds it is 11%, for 14 year olds it is 9%, and for adults it is 7%. Specific gravity of blood in newborns

Changes in the cellular composition of blood during postnatal ontogenesis
In newborns, the number of red blood cells is relatively higher than in adults and ranges from 5.9-6.1 * 1012/l. By the 12th day after birth it averages 5.4 * 1012/l, and by

Features of cardiac activity in children
In newborns, cardiac adaptation occurs vascular system to existence in the extrauterine period. The heart is round in shape and the atria are relatively larger than the ventricles of an adult

Functional properties of the vascular system in children
The development of blood vessels as they grow older is accompanied by an increase in their length and diameter. At an early age, the diameter of the veins and arteries is approximately the same. But the older the child, the more the diameter increases

Cardiac activity and vascular tone
In newborns, heterometric myogenic regulatory mechanisms are weakly manifested. Homeometric ones are well expressed. At birth there is normal innervation of the heart When the parasympathetic system is excited

Age-related features of external respiration functions
The structure of the respiratory tract of children differs markedly from the respiratory system of an adult. In the first days of postnatal ontogenesis, nasal breathing is difficult, since the child is born with insufficient development

Gas exchange in the lungs and tissues, gas transport in the blood
In the first days after birth, ventilation increases and the diffusion surface of the lungs increases. Due to the high rate of alveolar ventilation, there is more oxygen in the alveolar air of newborns (

Features of breathing regulation
The functions of the bulbar respiratory center are formed during intrauterine development. Premature babies born at 6-7 months are capable of independent breathing. Respiratory periodic movements

General patterns of nutritional development in ontogenesis
During ontogenesis, a gradual change in nutritional types occurs. The first stage is histotrophic nutrition from the reserves of the egg, yolk sac and uterine mucosa. Since the formation of the parade ground

Features of the functions of the digestive organs in infancy
After birth, the first digestive reflex is activated - sucking. It is formed very early in ontogenesis at 21-24 weeks of intrauterine development. Sucking begins as a result of irritation of the mechanical

Functions of the digestive organs in definitive nutrition
With the transition to definitive nutrition, the secretory and motor activity of the child’s digestive canal gradually approaches those of adulthood. Using predominantly dense

Metabolism and energy in childhood
The intake of nutrients into the child’s body on the first day does not cover its energy costs. Therefore, glycogen reserves in the liver and muscles are used. Its quantity in them is rapidly decreasing.

Development of thermoregulation mechanisms
In a newborn baby, the rectal temperature is higher than that of the mother and is 37.7-38.20 C. After 2-4 hours it decreases to 350 C. If the decrease is greater, this is one of the

Age-related features of kidney function
Morphologically, bud maturation ends by 5-7 years. Kidney growth continues up to 16 years. The kidneys of children under 6-7 months are in many ways reminiscent of an embryonic kidney. In this case, the weight of the kidneys (1:100) relates

Child's brain
In postnatal ontogenesis, the improvement of unconditional reflex functions occurs. Compared with an adult, newborns have much more pronounced processes of irradiation of excitation

Higher nervous activity of a child
A child is born with a relatively small number of inherited unconditioned reflexes, mainly of a protective and nutritional nature. However, after birth he finds himself in a new environment and these reflexes

There are the following methods for studying the functions of the central nervous system:

1. Method of cutting the brain stem at various levels. For example, between the medulla oblongata and the spinal cord.

2. Method of extirpation (removal) or destruction of parts of the brain.

3. Method of irritating various parts and centers of the brain.

4. Anatomical and clinical method. Clinical observations of changes in the functions of the central nervous system when any of its parts are affected, followed by a pathological examination.

5. Electrophysiological methods:

A. electroencephalography - registration of brain biopotentials from the surface of the scalp. The technique was developed and introduced into the clinic by G. Berger.

b. registration of biopotentials of various nerve centers; used in conjunction with stereotactic technique, in which electrodes are inserted into a strictly defined nucleus using micromanipulators.

V. evoked potential method, recording the electrical activity of brain areas during electrical stimulation of peripheral receptors or other areas;

6. method of intracerebral administration of substances using microinophoresis;

7. chronoreflexometry - determination of reflex time.

Properties of nerve centers

The nerve center (NC) is a collection of neurons in various parts of the central nervous system that provide regulation of any function of the body. For example, the bulbar respiratory center.

For the conduction of excitation through nerve centers, they are characterized by following features:

1. Unilateral conduction. It goes from the afferent, through the intercalary to the efferent neuron. This is due to the presence of interneuron synapses.

2. Central delay in the conduction of excitation. Those. Excitation along the NC is much slower than along the nerve fiber. This is explained by synaptic delay. Since there are most synapses in the central link of the reflex arc, the conduction speed there is the lowest. Based on this, reflex time is the time from the onset of exposure to the stimulus to the appearance of the response. The longer the central delay, the longer the reflex time. However, it depends on the strength of the stimulus. The larger it is, the shorter the reflex time and vice versa. This is explained by the phenomenon of summation of excitations in synapses. In addition, it is determined by the functional state of the central nervous system. For example, when the NC is tired, the duration of the reflex reaction increases.

3. Spatial and temporal summation. Temporal summation occurs, as in synapses, due to the fact that the more nerve impulses arrive, the more neurotransmitter is released in them, the higher the EPSP amplitude. Therefore, a reflex reaction can occur to several successive subthreshold stimuli. Spatial summation is observed when impulses from several neuron receptors go to the nerve center. When subthreshold stimuli act on them, the resulting postsynaptic potentials are summed up and a propagating AP is generated in the neuron membrane.

4. Transformation of the rhythm of excitation - a change in the frequency of nerve impulses when passing through the nerve center. The frequency may decrease or increase. For example, increasing transformation (increase in frequency) is due to the dispersion and multiplication of excitation in neurons. The first phenomenon occurs as a result of the division of nerve impulses into several neurons, the axons of which then form synapses on one neuron (Figure). Second, the generation of several nerve impulses during the development of an excitatory postsynaptic potential on the membrane of one neuron. The downward transformation is explained by the summation of several EPSPs and the appearance of one AP in the neuron.

5. Post-tetanic potentiation is an increase in the reflex response as a result of prolonged excitation of the neurons of the center. Under the influence of many series of nerve impulses passing at high frequency through synapses. A large amount of neurotransmitter is released at interneuron synapses. This leads to a progressive increase in the amplitude of the excitatory postsynaptic potential and long-term (several hours) excitation of neurons.

6. Aftereffect is a delay in the end of the reflex response after the cessation of the stimulus. Associated with the circulation of nerve impulses along closed circuits of neurons.

7. The tone of the nerve centers is a state of constant increased activity. It is caused by the constant supply of nerve impulses to the NC from peripheral receptors, the stimulating influence of metabolic products and other humoral factors on neurons. For example, a manifestation of the tone of the corresponding centers is the tone of a certain muscle group.

8. Automaticity or spontaneous activity of nerve centers. Periodic or constant generation of nerve impulses by neurons that arise spontaneously in them, i.e. in the absence of signals from other neurons or receptors. It is caused by fluctuations in metabolic processes in neurons and the effect of humoral factors on them.

9. Plasticity of nerve centers. This is their ability to change functional properties. In this case, the center acquires the ability to perform new functions or restore old ones after damage. The basis of plasticity N.Ts. lies the plasticity of synapses and membranes of neurons, which can change their molecular structure.

10. Low physiological lability and fatigue. N.Ts. can conduct pulses of only a limited frequency. Their fatigue is explained by fatigue of synapses and deterioration of neuronal metabolism.

Inhibition in the central nervous system

The phenomenon of central inhibition was discovered by I.M. Sechenov in 1862. He removed the frog's brain hemispheres and determined the time of the spinal reflex to irritation of the paw with sulfuric acid. Then to the thalamus, i.e. visual tubercles applied a crystal of table salt and found that the reflex time increased significantly. This indicated inhibition of the reflex. Sechenov concluded that the overlying N.Ts. when excited, they inhibit the underlying ones. Inhibition in the central nervous system prevents the development of excitation or weakens ongoing excitation. An example of inhibition could be the cessation of a reflex reaction against the background of the action of another, stronger stimulus.

Initially, a unitary-chemical theory of inhibition was proposed. It was based on Dale's principle: one neuron - one transmitter. According to it, inhibition is provided by the same neurons and synapses as excitation. Subsequently, the correctness of the binary chemical theory was proven. In accordance with the latter, inhibition is provided by special inhibitory neurons, which are intercalary. These are Renshaw cells of the spinal cord and Purkinje neurons. Inhibition in the central nervous system is necessary for the integration of neurons into a single nerve center.

The following inhibitory mechanisms are distinguished in the central nervous system:

1. Postsynaptic. It arises in the postsynaptic membrane of the soma and dendrites of neurons. Those. after the transmitting synapse. In these areas, specialized inhibitory neurons form axo-dendritic or axo-somatic synapses (Fig.). These synapses are glycinergic. As a result of the effect of GLI on glycine chemoreceptors of the postsynaptic membrane, its potassium and chloride channels open. Potassium and chloride ions enter the neuron, and IPSP develops. The role of chlorine ions in the development of IPSP is small. As a result of the resulting hyperpolarization, the excitability of the neuron decreases. The conduction of nerve impulses through it stops. The alkaloid strychnine can bind to glycine receptors on the postsynaptic membrane and turn off inhibitory synapses. This is used to demonstrate the role of inhibition. After the administration of strychnine, the animal develops cramps in all muscles.

2. Presynaptic inhibition. In this case, the inhibitory neuron forms a synapse on the axon of the neuron that approaches the transmitting synapse. Those. such a synapse is axo-axonal (Fig.). The mediator of these synapses is GABA. Under the influence of GABA, chloride channels of the postsynaptic membrane are activated. But in this case, chlorine ions begin to leave the axon. This leads to a small local but long-lasting depolarization of its membrane. A significant part of the sodium channels of the membrane is inactivated, which blocks the conduction of nerve impulses along the axon, and consequently the release of the neurotransmitter at the transmitting synapse. The closer the inhibitory synapse is located to the axon hillock, the stronger its inhibitory effect. Presynaptic inhibition is most effective in information processing, since the conduction of excitation is not blocked in the entire neuron, but only at its one input. Other synapses located on the neuron continue to function.

3. Pessimal inhibition. Discovered by N.E. Vvedensky. Occurs at a very high frequency of nerve impulses. A persistent, long-term depolarization of the entire neuron membrane and inactivation of its sodium channels develops. The neuron becomes unexcitable.

Both inhibitory and excitatory postsynaptic potentials can simultaneously arise in a neuron. Due to this, the necessary signals are isolated.

Related information.

There are the following methods for studying the functions of the central nervous system:

1. method cutting brain stem at various levels. For example, between the medulla oblongata and the spinal cord;

2. method extirpation(deletion) or destruction areas of the brain;

3. method irritation various parts and centers of the brain;

4. anatomical-clinical method. Clinical observations of changes in the functions of the central nervous system when any of its parts are damaged, followed by a pathological examination;

5. electrophysiological methods:

A. electroencephalography– registration of brain biopotentials from the surface of the scalp. The technique was developed and introduced into the clinic by G. Berger;

b. registration biopotentials various nerve centers; used in conjunction with the stereotactic technique, in which electrodes are inserted into a strictly defined nucleus using micromanipulators;

V. method evoked potentials, recording the electrical activity of areas of the brain during electrical stimulation of peripheral receptors or other areas.

6. method of intracerebral administration of substances using microinophoresis;

7. chronoreflexometry– determination of reflex time.

Properties of nerve centers

Nerve center(NC) is a collection of neurons in various parts of the central nervous system that provide regulation of any function of the body. For example, the bulbar respiratory center.

The following features are characteristic for the conduction of excitation through nerve centers:

1. Unilateral conduction. It goes from the afferent, through the intercalary, to the efferent neuron. This is due to the presence of interneuron synapses.

2. Central delay carrying out excitation. Those. Excitation along the NC is much slower than along the nerve fiber. This is explained by synaptic delay. Since there are most synapses in the central link of the reflex arc, the conduction speed there is the lowest. Based on this, reflex time – This is the time from the onset of exposure to a stimulus to the appearance of a response. The longer the central delay, the longer the reflex time. However, it depends on the strength of the stimulus. The larger it is, the shorter the reflex time and vice versa. This is explained by the phenomenon of summation of excitations in synapses. In addition, it is determined by the functional state of the central nervous system. For example, when the NC is tired, the duration of the reflex reaction increases.

3. Spatial and temporal summation. Time summation arises, as in synapses, due to the fact that the more nerve impulses are received, the more neurotransmitter is released in them, the higher the amplitude of excitation of postsynaptic potentials (EPSP). Therefore, a reflex reaction can occur to several successive subthreshold stimuli. Spatial summation observed when impulses from several receptor neurons go to the nerve center. When subthreshold stimuli act on them, the resulting postsynaptic potentials are summed up and a propagating AP is generated in the neuron membrane.

4. Rhythm transformation excitation - a change in the frequency of nerve impulses as they pass through the nerve center. The frequency may decrease or increase. For example, enhancing transformation(increase in frequency) due to dispersion And animation excitations in neurons. The first phenomenon occurs as a result of the division of nerve impulses into several neurons, the axons of which then form synapses on one neuron. The second is the generation of several nerve impulses during the development of an excitatory postsynaptic potential on the membrane of one neuron. Downward Transformation is explained by the summation of several EPSPs and the occurrence of one AP in the neuron.

5. Postetanic potentiation– this is an increase in the reflex reaction as a result of prolonged excitation of the neurons of the center. Under the influence of many series of nerve impulses passing at high frequency through synapses, a large amount of neurotransmitter is released at interneuron synapses. This leads to a progressive increase in the amplitude of the excitatory postsynaptic potential and long-term (several hours) excitation of neurons.

6. Aftereffect- this is a delay in the end of the reflex response after the cessation of the stimulus. Associated with the circulation of nerve impulses along closed circuits of neurons.

7. Tone of nerve centers– a state of constant increased activity. It is caused by the constant supply of nerve impulses to the NC from peripheral receptors, the stimulating influence of metabolic products and other humoral factors on neurons. For example, the manifestation of the tone of the corresponding centers is the tone of a certain muscle group.

8. Automatic(spontaneous activity) of nerve centers. Periodic or constant generation of nerve impulses by neurons that arise spontaneously in them, i.e. in the absence of signals from other neurons or receptors. It is caused by fluctuations in metabolic processes in neurons and the effect of humoral factors on them.

9. Plastic nerve centers. This is their ability to change functional properties. In this case, the center acquires the ability to perform new functions or restore old ones after damage. The plasticity of NCs is based on the plasticity of synapses and membranes of neurons, which can change their molecular structure.

10. Low physiological lability And fast fatiguability. NCs can conduct pulses of only a limited frequency. Their fatigue is explained by fatigue of synapses and deterioration of neuronal metabolism.

Inhibition in the central nervous system

Phenomenon central braking discovered by I.M. Sechenov in 1862. He removed the frog's brain hemispheres and determined the time of the spinal reflex to irritation of the paw with sulfuric acid. Then a crystal of table salt was placed on the thalamus (visual tubercles) and found that the reflex time increased significantly. This indicated inhibition of the reflex. Sechenov concluded that the overlying NCs, when excited, inhibit the underlying ones. Inhibition in the central nervous system prevents the development of excitation or weakens ongoing excitation. An example of inhibition could be the cessation of a reflex reaction against the background of the action of another, stronger stimulus.

Was originally proposed unitary chemical theory of inhibition. It was based on Dale's principle: one neuron - one transmitter. According to it, inhibition is provided by the same neurons and synapses as excitation. It was subsequently proven correct binary chemical theory. In accordance with the latter, inhibition is provided by special inhibitory neurons, which are intercalary. These are Renshaw cells of the spinal cord and Purkinje neurons. Inhibition in the central nervous system is necessary for the integration of neurons into a single nerve center.

The following are distinguished in the central nervous system: braking mechanisms:

1. Postsynaptic. It occurs in the postsynaptic membrane of the soma and dendrites of neurons, i.e. after the transmitting synapse. In these areas, specialized inhibitory neurons form axo-dendritic or axo-somatic synapses. These synapses are glycinergic. As a result of the effect of glycine on glycine chemoreceptors of the postsynaptic membrane, its potassium and chloride channels open. Potassium and chloride ions enter the neuron, and inhibition of postsynaptic potentials (IPSPs) develops. The role of chlorine ions in the development of IPSP is small. As a result of the resulting hyperpolarization, the excitability of the neuron decreases. The conduction of nerve impulses through it stops. Alkaloid strychnine can bind to glycine receptors on the postsynaptic membrane and turn off inhibitory synapses. This is used to demonstrate the role of inhibition. After the administration of strychnine, the animal develops cramps in all muscles.

2. Presynaptic braking. In this case, the inhibitory neuron forms a synapse on the axon of the neuron that approaches the transmitting synapse. Those. such a synapse is axo-axonal. The mediator of these synapses is GABA. Under the influence of GABA, chloride channels of the postsynaptic membrane are activated. But in this case, chlorine ions begin to leave the axon. This leads to a small local but long-lasting depolarization of its membrane. A significant part of the sodium channels of the membrane is inactivated, which blocks the conduction of nerve impulses along the axon, and consequently the release of the neurotransmitter at the transmitting synapse. The closer the inhibitory synapse is located to the axon hillock, the stronger its inhibitory effect. Presynaptic inhibition is most effective in information processing, since the conduction of excitation is not blocked in the entire neuron, but only at its one input. Other synapses located on the neuron continue to function.

3. Pessimal braking. Discovered by N.E. Vvedensky. Occurs at a very high frequency of nerve impulses. A persistent, long-term depolarization of the entire neuron membrane and inactivation of its sodium channels develops. The neuron becomes unexcitable.

Both inhibitory and excitatory postsynaptic potentials can simultaneously arise in a neuron. Due to this, the necessary signals are isolated.

The study of the central nervous system includes a group of experimental and clinical methods. Experimental methods include cutting, extirpation, destruction of brain structures, as well as electrical stimulation and electrical coagulation. Clinical methods include electroencephalography, evoked potentials, tomography, etc.

1. Cut and cut method. The method of cutting and switching off various parts of the central nervous system is done in various ways. Using this method, you can observe changes in conditioned reflex behavior.

2. Methods of cold switching off brain structures make it possible to visualize the spatio-temporal mosaic of electrical processes in the brain during the formation of a conditioned reflex in different functional states.

3. Methods of molecular biology are aimed at studying the role of DNA, RNA molecules and other biologically active substances in the formation of a conditioned reflex.

4. The stereotactic method consists in introducing an electrode into the animal’s subcortical structures, with which one can irritate, destroy, or inject chemicals. Thus, the animal is prepared for a chronic experiment. After the animal recovers, the conditioned reflex method is used.

Clinical methods make it possible to objectively assess the sensory functions of the brain, the state of the pathways, the brain’s ability to perceive and analyze stimuli, as well as identify pathological signs of disruption of the higher functions of the cerebral cortex.

Electroencephalography is one of the most common electrophysiological methods for studying the central nervous system. Its essence lies in recording rhythmic changes in the potentials of certain areas of the cerebral cortex between two active electrodes (bipolar method) or an active electrode in a certain zone of the cortex and a passive electrode superimposed on an area remote from the brain.

Electroencephalogram is a recording curve of the total potential of the constantly changing bioelectrical activity of a significant group of nerve cells. This amount includes synaptic potentials and partly action potentials of neurons and nerve fibers. Total bioelectrical activity is recorded in the range from 1 to 50 Hz from electrodes located on the scalp. The same activity from the electrodes, but on the surface of the cerebral cortex is called electrocorticogram. When analyzing EEG, the frequency, amplitude, shape of individual waves and the repeatability of certain groups of waves are taken into account.

Amplitude measured as the distance from the baseline to the peak of the wave. In practice, due to the difficulty of determining the baseline, peak-to-peak amplitude measurements are used.

Under frequency refers to the number of complete cycles completed by a wave in 1 second. This indicator is measured in hertz. The reciprocal of the frequency is called period waves. The EEG records 4 main physiological rhythms: ά -, β -, θ -. and δ – rhythms.

α – rhythm has a frequency of 8-12 Hz, amplitude from 50 to 70 μV. It predominates in 85-95% of healthy people over nine years of age (except for those born blind) in a state of quiet wakefulness with eyes closed and is observed mainly in the occipital and parietal regions. If it dominates, then the EEG is considered as synchronized.

Synchronization reaction called an increase in amplitude and a decrease in frequency of the EEG. The EEG synchronization mechanism is associated with the activity of the output nuclei of the thalamus. A variant of the ά-rhythm are “sleep spindles” lasting 2-8 seconds, which are observed when falling asleep and represent regular alternations of increasing and decreasing amplitude of waves in the frequencies of the ά-rhythm. Rhythms of the same frequency are:

μ – rhythm, recorded in the Rolandic sulcus, having an arched or comb-shaped waveform with a frequency of 7-11 Hz and an amplitude of less than 50 μV;

κ - rhythm, noted when applying electrodes in the temporal lead, having a frequency of 8-12 Hz and an amplitude of about 45 μV.

β - rhythm has a frequency from 14 to 30 Hz and a low amplitude - from 25 to 30 μV. It replaces the ά rhythm during sensory stimulation and emotional arousal. β- rhythm is most pronounced in the precentral and frontal areas and reflects high level functional activity of the brain. The change from ά - rhythm (slow activity) to β - rhythm (fast low-amplitude activity) is called desynchronization EEG is explained by the activating influence on the cerebral cortex of the reticular formation of the brainstem and the limbic system.

θ – rhythm has a frequency from 3.5 to 7.5 Hz, amplitude from 5 to 200 μV. In a waking person, the θ rhythm is usually recorded in the anterior regions of the brain during prolonged emotional stress and is almost always recorded during the development of the phases of slow-wave sleep. It is clearly registered in children who are in a state of displeasure. The origin of the θ rhythm is associated with the activity of the bridge synchronizing system.

δ – rhythm has a frequency of 0.5-3.5 Hz, amplitude from 20 to 300 μV. Occasionally recorded in all areas of the brain. The appearance of this rhythm in a awake person indicates a decrease in the functional activity of the brain. Stably fixed during deep slow-wave sleep. The origin of the δ - EEG rhythm is associated with the activity of the bulbar synchronizing system.

γ – waves have a frequency of more than 30 Hz and an amplitude of about 2 μV. Localized in the precentral, frontal, temporal, parietal areas of the brain. When visually analyzing the EEG, two indicators are usually determined: the duration of the ά-rhythm and the blockade of the ά-rhythm, which is recorded when a particular stimulus is presented to the subject.

In addition, the EEG has special waves that differ from the background ones. These include: K-complex, λ - waves, μ - rhythm, spike, sharp wave.

K - complex- This is a combination of a slow wave with a sharp wave, followed by waves with a frequency of about 14 Hz. The K-complex occurs during sleep or spontaneously in a waking person. The maximum amplitude is observed in the vertex and usually does not exceed 200 μV.

Λ – waves- monophasic positive sharp waves arising in the occipital area associated with eye movements. Their amplitude is less than 50 μV, frequency is 12-14 Hz.

M – rhythm– a group of arc-shaped and comb-shaped waves with a frequency of 7-11 Hz and an amplitude of less than 50 μV. They are registered in the central areas of the cortex (Roland's sulcus) and are blocked by tactile stimulation or motor activity.

Spike– a wave clearly different from background activity, with a pronounced peak lasting from 20 to 70 ms. Its primary component is usually negative. Spike-slow wave is a sequence of superficially negative slow waves with a frequency of 2.5-3.5 Hz, each of which is associated with a spike.

sharp wave– a wave that differs from background activity with an emphasized peak lasting 70-200 ms.

At the slightest attraction of attention to a stimulus, desynchronization of the EEG develops, that is, a reaction of ά-rhythm blockade develops. A well-defined ά-rhythm is an indicator of the body’s rest. A stronger activation reaction is expressed not only in the blockade of the ά - rhythm, but also in the strengthening of high-frequency components of the EEG: β - and γ - activity. A decrease in the level of functional state is expressed in a decrease in the proportion of high-frequency components and an increase in the amplitude of slower rhythms - θ- and δ-oscillations.

Method for recording impulse activity of nerve cells

The impulse activity of individual neurons or a group of neurons can be assessed only in animals and, in some cases, in humans during brain surgery. To record neural impulse activity of the human brain, microelectrodes with tip diameters of 0.5-10 microns are used. They can be made of stainless steel, tungsten, platinum-iridium alloys or gold. The electrodes are inserted into the brain using special micromanipulators, which allow the electrode to be precisely positioned to the desired location. The electrical activity of an individual neuron has a certain rhythm, which naturally changes under different functional states. The electrical activity of a group of neurons has a complex structure and on a neurogram looks like the total activity of many neurons, excited at different times, differing in amplitude, frequency and phase. The received data is processed automatically using special programs.

Evoked potential method

The specific activity associated with a stimulus is called an evoked potential. In humans, this is the registration of fluctuations in electrical activity that appear on the EEG with a single stimulation of peripheral receptors (visual, auditory, tactile). In animals, afferent pathways and switching centers of afferent impulses are also irritated. Their amplitude is usually small, therefore, to effectively isolate evoked potentials, the technique of computer summation and averaging of EEG sections that was recorded during repeated presentation of the stimulus is used. The evoked potential consists of a sequence of negative and positive deviations from the baseline and lasts about 300 ms after the end of the stimulus. The amplitude and latency period of the evoked potential are determined. Some of the components of the evoked potential, which reflect the entry of afferent excitations into the cortex through specific nuclei of the thalamus, and have a short latent period, are called primary response. They are registered in the cortical projection zones of certain peripheral receptor zones. Later components that enter the cortex through the reticular formation of the brainstem, nonspecific nuclei of the thalamus and limbic system and have a longer latent period are called secondary responses. Secondary responses, unlike primary ones, are recorded not only in the primary projection zones, but also in other areas of the brain, connected by horizontal and vertical nerve pathways. The same evoked potential can be caused by many psychological processes, and the same mental processes may be associated with different evoked potentials.

Tomographic methods

Tomography– is based on obtaining images of brain slices using special techniques. The idea of ​​this method was proposed by J. Rawdon in 1927, who showed that the structure of an object can be reconstructed from the totality of its projections, and the object itself can be described by many of its projections.

CT scan is a modern method that allows you to visualize the structural features of the human brain using a computer and an X-ray machine. In a CT scan, a thin beam of X-rays is passed through the brain, the source of which rotates around the head in a given plane; The radiation passing through the skull is measured by a scintillation counter. In this way, X-ray images of each part of the brain are obtained from different points. Then, using a computer program, these data are used to calculate the radiation density of the tissue at each point of the plane under study. The result is a high-contrast image of a brain slice in a given plane. Positron emission tomography– a method that allows you to assess metabolic activity in different parts of the brain. The test subject ingests a radioactive compound, which makes it possible to trace changes in blood flow in a particular part of the brain, which indirectly indicates the level of metabolic activity in it. The essence of the method is that each positron emitted by a radioactive compound collides with an electron; in this case, both particles mutually annihilate with the emission of two γ-rays at an angle of 180°. These are detected by photodetectors located around the head, and their registration occurs only when two detectors located opposite each other are excited simultaneously. Based on the data obtained, an image is constructed in the appropriate plane, which reflects the radioactivity of different parts of the studied volume of brain tissue.

Nuclear magnetic resonance method(NMR imaging) allows you to visualize the structure of the brain without the use of X-rays and radioactive compounds. A very strong magnetic field is created around the subject's head, which affects the nuclei of hydrogen atoms, which have internal rotation. Under normal conditions, the rotation axes of each core have a random direction. In a magnetic field, they change orientation in accordance with the lines of force of this field. Turning off the field leads to the fact that the atoms lose the uniform direction of the axes of rotation and, as a result, emit energy. This energy is recorded by a sensor, and the information is transmitted to a computer. The cycle of exposure to the magnetic field is repeated many times and as a result, a layer-by-layer image of the subject’s brain is created on the computer.

Rheoencephalography

Rheoencephalography is a method for studying the blood circulation of the human brain, based on recording changes in the resistance of brain tissue to high-frequency alternating current depending on the blood supply and allows one to indirectly judge the amount of total blood supply to the brain, the tone, elasticity of its vessels and the state of venous outflow.

Echoencephalography

The method is based on the property of ultrasound to be reflected differently from brain structures, cerebrospinal fluid, skull bones, and pathological formations. In addition to determining the size of the localization of certain brain formations, this method allows you to estimate the speed and direction of blood flow.

The study of the functional state of the ANS is of great diagnostic importance in clinical practice. The tone of the ANS is judged by the state of reflexes, as well as by the results of a number of special functional tests. Methods for clinical research of VNS are conditionally divided into the following groups:

• Patient interview;
• Study of dermographism (white, red, elevated, reflex);
• Study of vegetative pain points;
• Cardiovascular tests (capillaroscopy, adrenaline and histamine skin tests, oscillography, plethysmography, determination of skin temperature, etc.);
• Electrophysiological tests – study of electro-skin resistance using a direct current device;
• Determination of the content of biologically active substances, for example catecholamines in urine and blood, determination of blood cholinesterase activity.