A) Neurography – experimental technique for recording the electrical activity of individual neurons using microelectrode technology.
B) Electrocorticography - a method for studying the total bioelectrical activity of the brain removed from the surface of the cerebral cortex. The method has experimental value; it can extremely rarely be used in a clinical setting during neurosurgical operations.
IN) Electroencephalography
Electroencephalography (EEG) is a method for studying the total bioelectrical activity of the brain removed from the surface of the scalp. The method is widely used in the clinic and makes it possible to conduct a qualitative and quantitative analysis of the functional state of the brain and its reactions to stimuli.
Basic EEG rhythms:
| Name | View | Frequency | Amplitude | Characteristic |
| Alpha rhythm |  | 8-13 Hz | 50 µV | Recorded at rest and with eyes closed |
| Beta rhythm |  | 14-30 Hz | Up to 25 µV | Characteristic of a state of active activity |
| Theta rhythm | 4-7 Hz | 100-150 µV | Observed during sleep, in some diseases. | |
| Delta rhythm |  | 1-3 Hz | During deep sleep and anesthesia | |
| Gamma rhythm | 30-35 Hz | Up to 15 µV | It is registered in the anterior parts of the brain in pathological conditions. | |
| Convulsive paroxysmal waves |
Synchronization- the appearance of slow waves on the EEG, characteristic of an inactive state
Desynchronization- the appearance on the EEG of faster oscillations of smaller amplitude, which indicate a state of brain activation.
EEG technique: Using special contact electrodes fixed by a helmet to the scalp, the potential difference is recorded either between two active electrodes or between an active and inert electrode. To reduce the electrical resistance of the skin at the points of contact with the electrodes, it is treated with fat-dissolving substances (alcohol, ether), and gauze pads are moistened with a special electrically conductive paste. During EEG recording, the subject must be in a position that ensures muscle relaxation. First, background activity is recorded, then functional tests are performed (with opening and closing the eyes, rhythmic photostimulation, psychological tests). Thus, opening the eyes leads to inhibition of the alpha rhythm - desynchronization.
1. Telencephalon: general structural plan, cyto- and myeloarchitecture of the cerebral cortex (CBC). Dynamic localization of functions in KBP. The concept of sensory, motor and associative areas of the cerebral cortex.
2. Anatomy of the basal ganglia. The role of the basal ganglia in the formation of muscle tone and complex motor acts.
3. Morphofunctional characteristics of the cerebellum. Signs of its damage.
4. Methods for studying the central nervous system.
· Do the work in writing : In your protocol notebook, draw a diagram of the pyramidal (corticospinal) tract. Indicate the localization in the body of the cell bodies of neurons, the axons of which make up the pyramidal tract, and the features of the passage of the pyramidal tract through the brain stem. Describe the functions of the pyramidal tract and the main symptoms of its damage.
LABORATORY WORK
Job No. 1.
Human electroencephalography.
Using the Biopac Student Lab system, record the EEG of the subject 1) in a relaxed state with his eyes closed; 2) with eyes closed when solving a mental problem; 3) with eyes closed after a test with hyperventilation; 4) with open eyes. Assess the frequency and amplitude of the recorded EEG rhythms. In the conclusion, characterize the main EEG rhythms recorded in different states.
Job No. 2.
Functional tests to identify cerebellar lesions
1) Romberg's test. The subject, with his eyes closed, stretches his arms forward and places his feet in one line - one in front of the other. The inability to maintain balance in the Romberg position indicates an imbalance and damage to the archicerebellum - the most phylogenetically ancient structures of the cerebellum.
2) Finger test. The subject is asked to touch the tip of his nose with his index finger. The movement of the hand to the nose should be carried out smoothly, first with open, then with closed eyes. If the cerebellum is damaged (paleocerebellum disorder), the subject misses, and as the finger approaches the nose, a tremor (shaking) of the hand appears.
3) Schilber's test. The subject stretches his arms forward, closes his eyes, raises one arm vertically up, and then lowers it to the level of the other arm extended horizontally. When the cerebellum is damaged, hypermetry is observed - the hand drops below the horizontal level.
4) Test for adiadochokinesis. The subject is asked to quickly perform alternately opposite, complexly coordinated movements, for example, to pronate and supinate the hands of outstretched arms. If the cerebellum (neocerebellum) is damaged, the subject cannot perform coordinated movements.
1) What symptoms will a patient experience if a hemorrhage occurs in the internal capsule of the left half of the brain, where the pyramidal tract passes?
2) Which part of the central nervous system is affected if the patient has hypokinesia and tremor at rest?
Lesson No. 21
Lesson topic: Anatomy and physiology of the autonomic nervous system
Purpose of the lesson: Study the general principles of the structure and functioning of the autonomic nervous system, the main types of autonomic reflexes, and the general principles of nervous regulation of the activity of internal organs.
1) Lecture material.
2) Loginov A.V. Physiology with the basics of human anatomy. – M, 1983. – 373-388.
3) Alipov N.N. Fundamentals of medical physiology. – M., 2008. – P. 93-98.
4) Human physiology / Ed. G.I.Kositsky. – M., 1985. – P. 158-178.
Questions for independent extracurricular work of students:
1. Structural and functional features of the autonomic nervous system (ANS).
2. Characteristics of the nerve centers of the sympathetic nervous system (SNS), their localization.
3. Characteristics of the nerve centers of the parasympathetic nervous system (PSNS), their localization.
4. The concept of the metasympathetic nervous system; features of the structure and function of the autonomic ganglia as peripheral nerve centers for the regulation of autonomic functions.
5. Features of the influence of the SNS and PSNS on internal organs; ideas about the relative antagonism of their actions.
6. Concepts of cholinergic and adrenergic systems.
7. Higher centers for the regulation of autonomic functions (hypothalamus, limbic system, cerebellum, cerebral cortex).
· Using materials from lectures and textbooks, Fill the table "Comparative characteristics of the effects of the sympathetic and parasympathetic nervous system."
LABORATORY WORK
Work 1.
Sketching the reflex patterns of the sympathetic and parasympathetic nervous system.
In your practical work notebook, sketch out diagrams of the SNS and PSNS reflexes, indicating their constituent elements, mediators and receptors; conduct a comparative analysis of reflex arcs of autonomic and somatic (spinal) reflexes.
Work 2.
Study of the Danini-Aschner oculocardiac reflex
Methodology:
1. The subject’s heart rate in 1 minute is determined from the pulse at rest.
2. Carry out moderate pressing the subject's eyeballs with the thumb and forefinger for 20 seconds. In this case, 5 seconds after the start of pressure, the heart rate of the subject is determined by the pulse for 15 seconds. Calculate the heart rate during the test for 1 minute.
3. The subject’s heart rate for 1 minute is determined from the pulse 5 minutes after the test.
The results of the study are entered into the table:
Compare the results obtained from three subjects.
The reflex is considered positive if the subject had a decrease in heart rate by 4-12 beats per minute;
If the heart rate has not changed or decreased by less than 4 beats per minute, such a test is considered non-reactive.
If the heart rate has decreased by more than 12 beats per minute, then such a reaction is considered excessive and may indicate that the subject has severe vagotonia.
If the heart rate increases during the test, then either the test was performed incorrectly (excessive pressure) or the subject has sympathicotonia.
Draw the reflex arc of this reflex with the designation of the elements.
In the conclusion, explain the mechanism of implementation of the reflex; indicate how the autonomic nervous system affects the functioning of the heart.
To check your understanding of the material, answer the following questions:
1) How does the effect on the effectors of the sympathetic and parasympathetic nervous system change with the administration of atropine?
2) Which autonomic reflex (sympathetic or parasympathetic) takes longer and why? When answering the question, remember the type of preganglionic and postganglionic fibers and the speed of impulse transmission through these fibers.
3) Explain the mechanism of pupil dilation in humans during anxiety or pain.
4) By prolonged irritation of the somatic nerve, the muscle of the neuromuscular preparation is brought to the point of fatigue and has stopped responding to the stimulus. What will happen to it if you simultaneously start irritating the sympathetic nerve going to it?
5) Do autonomic or somatic nerve fibers have more rheobase and chronaxy? Which structures are more lability - somatic or vegetative?
6) The so-called “lie detector” is designed to check whether a person is telling the truth when answering questions asked. The principle of operation of the device is based on the use of the influence of CBP on vegetative functions and the difficulties of controlling vegetatives. Suggest parameters that this device can record
7) The animals in the experiment were administered two different drugs. In the first case, pupil dilation and skin pallor were observed; in the second case - constriction of the pupil and lack of reaction of the skin blood vessels. Explain the mechanism of action of the drugs.
Lesson No. 22
Classification, structure and functions of neurons. Neuroglia.
PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM.
Central nervous system (CNS ) is a complex of various formations of the spinal cord and brain that provide perception, processing, storage and reproduction of information, as well as the formation of adequate reactions of the body to changes in the external and internal environment.
The structural and functional elements of the central nervous system are neurons. These are highly specialized cells of the body, extremely different in their structure and functions. No two neurons in the central nervous system are alike. The human brain contains 25 billion neurons. In general terms, all neurons have a body - a soma and processes - dendrites and axons. There is no exact classification of neurons, but they are conventionally divided according to structure and function into the following groups:
1. According to body shape.
· Polygonal.
· Pyramid.
· Round.
· Oval.
2. By the number and nature of processes.
· Unipolar - have one process.
· Pseudounipolar - one process extends from the body, which then divides into 2 branches.
· Bipolar – 2 processes, one dendrite-like, the other an axon.
· Multipolar - have 1 axon and many dendrites.
3. According to the transmitter released by the neuron at the synapse.
· Cholinergic.
· Adrenegric.
· Serotonergic.
· Peptidergic, etc.
4. By function.
· Afferent or sensitive. They serve to perceive signals from the external and internal environment and transmit them to the central nervous system.
· Interneurons or interneurons are intermediate. Provide processing, storage and transmission of information to efferent neurons. There are most of them in the central nervous system.
· Efferent or motor. They generate control signals and transmit them to peripheral neurons and executive organs.
5. According to physiological role.
· Exciting.
· Brake.
The soma of neurons is covered with a multilayer membrane, which ensures conduction of the action potential to the initial segment of the axon - the axon hillock. The soma contains the nucleus, Golgi apparatus, mitochondria, and ribosomes. Ribosomes synthesize tigroid, which contains RNA and is necessary for protein synthesis. A special role is played by microtubules and thin filaments - neurofilaments. They are present in the soma and processes. They provide transport of substances from the soma through the processes and back. In addition, due to neurofilaments, the movement of processes occurs. On dendrites there are projections for synapses - spines, through which information enters the neuron. The signal travels along axons to other neurons or executive organs. Thus, the general functions of CNS neurons are reception, encoding and storage of information, as well as the production of neurotransmitters. Neurons, through numerous synapses, receive signals in the form of postsynaptic potentials. Then they process this information and form a certain response. Therefore, they perform and integrative, those. unifying function.
In addition to neurons, the central nervous system contains cells neuroglia. Glial cells are smaller than neurons, but make up 10% of the brain volume. Depending on the size and number of processes, astrocytes, oligodendrocytes, and microgliocytes are distinguished. Neurons and glial cells are separated by a narrow (20 nm) intercellular gap. These slits are interconnected and form the extracellular space of the brain, filled with interstitial fluid. Due to this space, neurons and glia are provided with oxygen and nutrients. Glial cells rhythmically increase and decrease at a frequency of several oscillations per hour. This promotes the flow of axoplasm along the axons and the movement of intercellular fluid. Thus, glions serve as a supporting apparatus of the central nervous system, ensure metabolic processes in neurons, and absorb excess neurotransmitters and their decay products. It is assumed that glia are involved in the formation of conditioned reflexes and memory.
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. For example, removal of the cerebellum.
3. Method irritation 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:
· Electroencephalography– registration of brain biopotentials from the surface of the scalp. The technique was developed and introduced into the clinic by G. Berger.
· 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.
· The method of 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.
8. Method modeling.
BIP - INSTITUTE OF LAW
M. V. PIVOVARCHIK
ANATOMY AND PHYSIOLOGY
CENTRAL NERVOUS SYSTEM
Minsk
BIP - INSTITUTE OF LAW
M. V. PIVOVARCHIK
ANATOMY AND PHYSIOLOGY
CENTRAL NERVOUS SYSTEM
Educational and methodological manual
Belarusian Institute of Law
Reviewers: Ph.D. biol. Sciences Associate Professor Ledneva I. V.,
Ph.D. honey. Sciences, Associate Professor Avdey G. M.
Pivovarchik M. V.
Anatomy and physiology of the central nervous system: Educational method. allowance / M. V. Pivovarchik. Mn.: BIP-S Plus LLC, 2005. – 88 p.
The manual corresponds to the structure of the course “Anatomy and Physiology of the Central Nervous System”, it discusses the main topics that make up the content of the course. The general structure of the nervous system, spinal cord and brain is described in detail, the features of the structure and functioning of the autonomic and somatic parts of the human nervous system, and the general principles of its functioning are described. At the end of each of the nine topics in the manual there are questions for self-control. Intended for full-time and part-time students majoring in psychology.
© Pivovarchik M.V., 2005
TOPIC 1. Methods for studying the nervous system.. 4
TOPIC 2. Structure and functions of nervous tissue. 7
TOPIC 3. Physiology of synaptic transmission. 19
TOPIC 4. General structure of the nervous system.. 26
TOPIC 5. Structure and functions of the spinal cord. 31
TOPIC 6. Structure and functions of the brain. 35
Topic 7. Motor function of the central nervous system... 57
TOPIC 8. Autonomic nervous system. 70
Topic 9. General principles of the functioning of the nervous system.. 78
BASIC LITERATURE... 87
ADDITIONAL READING... 87
TOPIC 1. Methods for studying the nervous system
Neurobiological methods.
Magnetic resonance imaging method.
Neuropsychological methods.
Neurobiological methods. In theoretical studies of the physiology of the human nervous system, the study of the central nervous system of animals plays an important role. This field of knowledge is called neurobiology. The structure of nerve cells, as well as the processes occurring in them, remain unchanged both in primitive animals and in humans. The exception is the cerebral hemispheres. Therefore, a neuroscientist can always study this or that issue of the physiology of the human brain using simpler, cheaper and more accessible objects. Such objects can be invertebrate animals. In recent years, intravital sections of the brain of newborn rats and guinea pigs and even a culture of nervous tissue grown in the laboratory have been increasingly used for these purposes. Such material can be used to study the mechanisms of functioning of individual nerve cells and their processes. For example, cephalopods (squid, cuttlefish) have very thick, giant axons (500–1000 µm in diameter), through which excitation is transmitted from the cephalic ganglion to the muscles of the mantle. The molecular mechanisms of excitation are being studied in this facility. Many mollusks have very large neurons in their nerve ganglia, which replace the brain - up to 1000 microns in diameter. These neurons are used to study the functioning of ion channels, the opening and closing of which is controlled by chemicals.
To record the bioelectrical activity of neurons and their processes, microelectrode technology is used, which, depending on the objectives of the study, has many features. Typically, two types of microelectrodes are used: metal and glass. To record the activity of single neurons, the microelectrode is fixed in a special manipulator, which allows it to be moved through the animal’s brain with high precision. Depending on the research objectives, the manipulator can be mounted on the animal’s skull or separately. The nature of the recorded bioelectrical activity is determined by the diameter of the microelectrode tip. For example, with a microelectrode tip diameter of no more than 5 μm, action potentials of single neurons can be recorded. When the diameter of the microelectrode tip is more than 10 microns, the activity of tens and sometimes hundreds of neurons is simultaneously recorded.
Magnetic resonance imaging method. Modern methods make it possible to see the structure of the human brain without damaging it. The magnetic resonance imaging method makes it possible to observe a series of successive “slices” of the brain on a monitor screen without causing any harm to it. This method makes it possible to study, for example, malignant brain tumors. The brain is irradiated with an electromagnetic field using a special magnet. Under the influence of a magnetic field, the dipoles of brain fluids (for example, water molecules) take its direction. After removing the external magnetic field, the dipoles return to their original state, and a magnetic signal appears, which is detected by special sensors. This echo is then processed using a powerful computer and displayed on a monitor screen using computer graphics methods.
Positron emission tomography. Positron emission tomography (PET) has an even higher resolution. The study is based on the introduction of a positron-emitting short-lived isotope into the cerebral bloodstream. Data about the distribution of radioactivity in the brain is collected by a computer over a specific scanning time and then reconstructed into a three-dimensional image.
Electrophysiological methods. Back in the 18th century. Italian doctor Luigi Galvani noticed that prepared frog legs contracted when they came into contact with metal. He concluded that the muscles and nerve cells of animals produce electricity. In Russia, similar studies were carried out by I.M. Sechenov: he was the first to record bioelectrical oscillations from the medulla oblongata of a frog. At the beginning of the 20th century, using much more advanced instruments, the Swedish researcher G. Berger recorded the bioelectric potentials of the human brain, which are now called electroencephalogram(EEG). In these studies, the basic rhythm of human brain biocurrents was recorded for the first time - sinusoidal oscillations with a frequency of 8 - 12 Hz, which was called the alpha rhythm. Modern methods of clinical and experimental electroencephalography have made a significant step forward thanks to the use of computers. Typically, several dozen cup electrodes are applied to the surface of the scalp during a clinical examination of a patient. These electrodes are then connected to a multi-channel amplifier. Modern amplifiers are very sensitive and make it possible to record electrical oscillations from the brain with an amplitude of only a few microvolts, then a computer processes the EEG for each channel.
When studying the background EEG, the leading indicator is the alpha rhythm, which is recorded mainly in the posterior parts of the cortex in a state of quiet wakefulness. When sensory stimuli are presented, suppression, or “blockade,” of the alpha rhythm occurs, the duration of which is longer, the more complex the image. An important direction in the use of EEG is the study of spatio-temporal relationships of brain potentials during the perception of sensory information, i.e., taking into account the time of perception and its cerebral organization. For these purposes, synchronous multichannel EEG recording is performed during the perception process. In addition to recording background EEG, methods are used to study brain function registration of evoked (EP) or event-related (ERP) brain potentials. These methods are based on the idea that an evoked or event-related potential is a brain response to sensory stimulation, comparable in duration to the processing time of the stimulus. Event-related brain potentials represent a broad class of electrophysiological phenomena that are isolated from the “background” or “raw” electroencephalogram using special methods. The popularity of the EP and ERP methods is explained by the ease of recording and the ability to observe the activity of many areas of the brain in dynamics over a long period of time when performing tasks of any complexity.
Particular physiology of the central nervous system is a section that studies the functions of the structures of the brain and spinal cord, as well as the mechanisms of their implementation.
Methods for studying the functions of the central nervous system include the following.
Electroencephalography- a method for recording biopotentials generated by the brain when they are removed from the surface of the scalp. The value of such biopotentials is 1-300 μV. They are removed using electrodes applied to the surface of the scalp at standard points over all lobes of the brain and some of their areas. Biopotentials are fed to the input of an electroencephalograph device, which amplifies them and records them in the form of an electroencephalogram (EEG) - a graphical curve of continuous changes (waves) of brain biopotentials. The frequency and amplitude of electroencephalographic waves reflect the level of activity of the nerve centers. Taking into account the amplitude and frequency of the waves, four main EEG rhythms are distinguished (Fig. 1).
Alpha rhythm has a frequency of 8-13 Hz and an amplitude of 30-70 μV. This is a relatively regular, synchronized rhythm recorded in a person who is in a state of wakefulness and rest. It is detected in approximately 90% of people who are in a calm environment, with maximum muscle relaxation, with their eyes closed or in the dark. The alpha rhythm is most pronounced in the occipital and parietal lobes of the brain.
Beta rhythm characterized by irregular waves with a frequency of 14-35 Hz and an amplitude of 15-20 μV. This rhythm is recorded in a awake person in the frontal and parietal areas, when opening the eyes, the action of sound, light, addressing the subject, performing physical actions. It indicates a transition of nervous processes to a more active, active state and an increase in the functional activity of the brain. The change from the alpha rhythm or other electroencephalographic rhythms of the brain to the beta rhythm is calleddesynchronization reaction, or activation.
Rice. 1. Scheme of the main rhythms of human brain biopotentials (EEG): a - rhythms recorded from the surface of the scalp in a mow; 6 - the action of light causes a desynchronization reaction (change of α-rhythm to β-rhythm)
Theta rhythm has a frequency of 4-7 Hz and an amplitude of up to 150 μV. It manifests itself in the late stages of a person falling asleep and the development of anesthesia.
Delta rhythm characterized by a frequency of 0.5-3.5 Hz and a large (up to 300 μV) amplitude of will. It is recorded over the entire surface of the brain during deep sleep or anesthesia.
The main role in the origin of EEG is assigned to postsynaptic potentials. It is believed that the nature of EEG rhythms is most influenced by the rhythmic activity of pacemaker neurons and the reticular formation of the brain stem. In this case, the thalamus induces high-frequency rhythms in the cortex, and the reticular formation of the brain stem - low-frequency rhythms (theta and delta).
The EEG method is widely used to record neural activity in sleep and wakefulness states; to identify areas of increased activity in the brain, for example in epilepsy; to study the influence of medicinal and narcotic substances and solve other problems.
Evoked potential method allows you to record changes in the electrical potentials of the cortex and other brain structures caused by stimulation of various receptor fields or pathways associated with these brain structures. The biopotentials of the cortex that arise in response to instantaneous stimulation are wave-like in nature and last up to 300 ms. To isolate evoked potentials from spontaneous electroencephalological waves, complex computer processing of EEG is used. This technique is used experimentally and clinically to determine the functional state of the receptor, conductor and central parts of the sensory systems.
Microelectrode method allows, using the thinnest electrodes inserted into a cell or supplied to neurons located in a certain area of the brain, to record cellular or extracellular electrical activity, as well as to influence them with electric currents.
Stereotactic method allows the introduction of probes and electrodes into specified brain structures for therapeutic and diagnostic purposes. Their introduction is carried out taking into account the three-dimensional spatial coordinates of the location of the brain structure of interest, which are described in stereotaxic atlases. The atlases indicate at what angle and to what depth relative to the characteristic anatomical points of the skull an electrode or probe should be inserted to reach the brain structure of interest. In this case, the patient's head is fixed in a special holder.
Irritation method. Stimulation of various brain structures is most often carried out using a weak electric current. Such irritation is easily dosed, does not cause damage to nerve cells and can be applied repeatedly. Various biologically active substances are also used as irritants.
Methods of cutting, extirpation (removal) and functional blockade of nerve structures. Removal of brain structures and their transection were widely used in experiments during the initial period of accumulation of knowledge about the brain. Currently, information about the physiological role of various structures of the central nervous system is supplemented by clinical observations of changes in the state of the functions of the brain or other organs in patients who have undergone removal or destruction of individual structures of the nervous system (tumors, hemorrhages, injuries).
With a functional blockade, the functions of the nervous structures are temporarily switched off by introducing inhibitory substances, the effects of special electric currents, and cooling.
Rheoencephalography. It is a technique for studying pulse changes in blood supply to the cerebral vessels. It is based on measuring the resistance of nervous tissue to electric current, which depends on the degree of their blood supply.
Echoencephalography. Allows you to determine the location and size of compactions and cavities in the brain and bones of the skull. This technique is based on recording ultrasonic waves reflected from the tissues of the head.
Computed tomography (visualization) methods. They are based on recording signals from short-lived isotopes that have penetrated into the brain tissue using magnetic resonance, positron emission tomography and recording the absorption of X-rays passing through the tissue. Provides clear layer-by-layer and three-dimensional images of brain structures.
Methods for studying conditioned reflexes and behavioral reactions. Allows you to study the integrative functions of the higher parts of the brain. These methods are discussed in more detail in the section on integrative brain functions.
Modern research methods
Electroencephalography(EEG) - registration of electromagnetic waves arising in the cerebral cortex during rapid changes in cortical field potentials.
Magnetoencephalography(MEG) - registration of magnetic fields in the cerebral cortex; The advantage of MEG over EEG is due to the fact that MEG does not experience distortion from the tissues covering the brain, does not require an indifferent electrode, and reflects only sources of activity parallel to the skull.
Positive emission tomography(PET) is a method that allows, using appropriate isotopes introduced into the blood, to evaluate the structures of the brain, and based on the speed of their movement, the functional activity of nervous tissue.
Magnetic resonance imaging(MRI) - is based on the fact that various substances with paramagnetic properties are capable of polarizing in a magnetic field and resonating with it.
Thermoencephaloscopy- measures local metabolism and blood flow of the brain by its heat production (its disadvantage is that it requires an open surface of the brain; it is used in neurosurgery).
Electroencephalography (EEG) is a recording of the total electrical activity of the brain. Electrical vibrations in the cerebral cortex were discovered by R. Keton (1875) and V.Ya. Danilevsky (1876). EEG recording is possible both on the surface of the scalp and from the surface of the cortex in experiments and in the clinic during neurosurgical operations. In this case, it is called an electrocorticogram. EEG is recorded using bipolar (both active) or unipolar (active and indifferent) electrodes applied in pairs and symmetrically in the frontal-polar, frontal, central, parietal, temporal and occipital regions of the brain. In addition to recording background EEG, functional tests are used: exteroceptive (light, auditory, etc.), proprioceptive, vestibular stimuli, hyperventilation, sleep. The EEG records four main physiological rhythms: alpha, beta, gamma and delta rhythms.
Evoked potential method (EP) is a measurement of the electrical activity of the brain that occurs in response to stimulation of receptors, afferent pathways and switching centers of afferent impulses. In clinical practice, EPs are usually obtained in response to stimulation of receptors, mainly visual, auditory or somatosensory. EPs are recorded when recording EEG, usually from the surface of the head, although they can also be recorded from the surface of the cortex, as well as in deep structures of the brain, for example, in the thalamus. VP technique used for an objective study of sensory functions, the process of perception, and brain pathways under physiological and pathological conditions (for example, with brain tumors, the shape of the EP is distorted, the amplitude decreases, and some components disappear).
Functional computed tomography:
Positron emission tomography is an intravital method of functional isotope mapping of the brain. The technique is based on the introduction of isotopes (O 15, N 13, F 18, etc.) into the bloodstream in combination with deoxyglucose. The more active an area of the brain, the more it absorbs labeled glucose, the radioactive radiation of which is recorded by detectors located around the head. Information from the detectors is sent to a computer, which creates “slices” of the brain at the recorded level, reflecting the uneven distribution of the isotope due to the metabolic activity of brain structures.
Functional magnetic resonance imaging is based on the fact that with the loss of oxygen, hemoglobin acquires paramagnetic properties. The higher the metabolic activity of the brain, the greater the volumetric and linear blood flow in a given region of the brain and the lower the ratio of paramagnetic deoxyhemoglobin to oxyhemoglobin. There are many foci of activation in the brain, which is reflected in the heterogeneity of the magnetic field. This method allows us to identify actively working areas of the brain.
Rheoencephalography is based on recording changes in tissue resistance to high-frequency alternating current depending on their blood supply. Rheoencephalography makes it possible to indirectly judge the amount of general blood supply to the brain and its asymmetry in various vascular zones, the elasticity tone of brain vessels, and the state of sudden outflow.
Echoencephalography is based on the property of ultrasound to be reflected to varying degrees from the structures of the head - brain tissue and its pathological formations, cerebrospinal fluid, skull bones, etc. In addition to determining the localization of certain brain structures (especially the median ones), echoencephalography, through the use of the Doppler effect, allows one to obtain information about the speed and direction of blood movement in the vessels involved in the blood supply to the brain ( Doppler effect- a change in the frequency and length of waves recorded by the receiver, caused by the movement of their source or the movement of the receiver.).
Chronaximetry allows you to determine the excitability of nervous and muscle tissue by measuring the minimum time (chronaxy) under the action of a stimulus of double threshold strength. Chronaxy of the motor system is often determined. Chronaxia increases with damage to spinal motor neurons and decreases with damage to cortical motor neurons. Its value is influenced by the condition of the trunk structures. For example, the thalamus and the red nucleus. You can also determine the chronaxy of sensory systems - cutaneous, visual, vestibular (by the time of occurrence of sensations), which allows us to judge the function of the analyzers.
Stereotactic method allows, using a device for precise movement of electrodes in the frontal, sagittal and vertical directions, to insert an electrode (or micropipette, thermocouple) into various structures of the brain. Through the inserted electrodes, it is possible to record the bioelectrical activity of a given structure, irritate or destroy it, and introduce chemicals through microcannulas into the nerve centers or ventricles of the brain.
Irritation method various structures of the central nervous system with a weak electric current using electrodes or chemicals (solutions of salts, mediators, hormones) supplied using micropipettes mechanically or using electrophoresis.
Shutdown method different parts of the central nervous system can be produced mechanically, electrolytically, using freezing or electrocoagulation, as well as with a narrow beam or by injecting hypnotics into the carotid artery, you can reversibly turn off some parts of the brain, for example the cerebral hemisphere.
Cutting method at different levels of the central nervous system in an experiment it is possible to obtain spinal, bulbar, mesocephalic, diencephalic, decorticated organisms, split brain (commissurotomy operation); disrupt the connection between the cortical region and underlying structures (lobotomy operation), between the cortex and subcortical structures (neuronally isolated cortex). This method allows us to better understand the functional role of both the centers located below the transection and the higher centers that are switched off.
Pathoanatomical method– intravital observation of dysfunction and post-mortem examination of the brain.
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