Neurophysiology is a branch of physiology that studies the functions of the nervous system and neurons, which are its main structural units. It is closely related to psychology, ethology, neuroanatomy, as well as many other sciences that study the brain. However, this is a general definition. It is worth expanding it and paying attention to other aspects related to this topic. And there are many of them.
A little history
It was in the 17th century that the first ideas about such a (not yet existing) scientific field as neurophysiology were put forward. Its development might not have happened if not for the accumulation of information about histological and anatomical. Experiments in the study of a new medical branch began in the 19th century - before that there were only theories. The first of which were put forward by R. Descartes.
True, initially the experiments were not particularly humane. First of all, scientists (C. Bell and F. Magendie) managed to find out that after cutting the posterior spinal roots, sensitivity disappears. And if you do the same with the front ones, the ability to move will disappear.
But the most famous neurophysiological experiment (which, by the way, is known to each of us) was conducted by I. P. Pavlov. It was he who discovered conditioned reflexes, which gave access to the objective recording of those nervous processes that occur in the cerebral cortex. All this is neurophysiology. which was now discussed, was determined during experiments conducted within the framework of this medical section.
Modern research
Neurophysiology, unlike neurology, neurobiology and all other sciences with which it is connected, has one difference. And it consists in the following: this section deals directly with the theoretical development of neuroscience as a whole.
Nowadays, science, like medicine, has come very far. And at the present stage, all functions of neurophysiology are built on the study and understanding of the integrative activity of our nervous system. What happens with the help of implanted and surface electrodes, as well as temperature stimuli of the central nervous system.
At the same time, the development of the study of cellular mechanisms continues - it also involves the use of modern microelectrode technology. This is a rather complex and painstaking process, because in order to begin the study, it is necessary to “implant” a microelectrode inside the neuron. This is the only way they will receive information regarding the development of inhibition and excitation processes.
Electron microscopy
It is also used by scientists today. makes it possible to study exactly how information is encoded and transmitted in our brain. The basics of neurophysiology have been studied, and thanks to modern technologies, there are already entire centers in which scientists model individual nerve networks and neurons. Accordingly, today neurophysiology is also a science related to cybernetics, chemistry and bionics. And the progress is obvious - today the diagnosis and subsequent treatment of epilepsy, multiple sclerosis, stroke and musculoskeletal disorders are a reality.
Clinical experiments
Neurophysiology of the human brain (both brain and spinal cord) examines its specific functions using electrophysiological measurement methods. The process is experimental - only thanks to external influences can the appearance of evoked potentials be achieved. These are bioelectric signals.
This method makes it possible to obtain information about the functional state of the brain and the activity of its deep parts, and you don’t even need to penetrate them. Today, this method is widely used in clinical neurophysiology. The goal is to find out information regarding the state of different sensory systems, such as touch, hearing, vision. In this case, both peripheral and central nerves are examined.
The benefits of this method are obvious. Doctors receive objective information directly from the body. There is no need to interview the patient. This is especially good in the case of small children or people with impaired consciousness who, due to their age or condition, cannot express feelings in words.
Surgery
This topic is worth noting. There is such a thing as surgical neurophysiology. This is, in other words, the “applied” sphere. It is practiced by neurophysiological surgeons who directly during the operation observe how their patient’s nervous system functions. This process is most often accompanied by an electrophysiological study of certain areas of the operated patient’s central nervous system. This, by the way, has to do with a broad clinical discipline called neuromonitoring.
Evoked potential method
It’s worth telling about it in more detail. Neurophysiology is a discipline that allows us to find out a lot of important information that can contribute to the treatment of the patient. And the evoked potential method is applied to visual, acoustic, auditory, somatosensory and transcranial functions.
Its essence is as follows: the doctor identifies and averages the weakest potentials of bioelectrical brain activity, which is a response to afferent stimuli. The technique is reliable because it involves the use of a single interpretation algorithm.
Thanks to such studies, it is possible to identify neurological disorders of varying degrees in the patient, as well as disorders that affect the sensorimotor cortex of the brain, retinal pathways, hearing function, etc. Moreover, the ability to calculate the effect of anesthesia on the human body has become real. Now, using this method, it is possible to assess coma, predict its development and calculate the probable
Specialization
Neurophysiologists are not only doctors, but also analysts. Through various studies, a specialist can determine how severely the central nervous system is affected. This makes it possible to establish an accurate diagnosis and prescribe competent, correct treatment.
Take, for example, a common headache - it can be a consequence of vascular spasms and increased intracranial pressure. But often this is also a symptom of a developing tumor or even a convulsive syndrome. Fortunately, nowadays there are several methods by which doctors find out what exactly is happening to the patient. We can tell you about them one last time.
Types of research
So, the first is EEG, or rheoencephalography, as doctors call it. Epilepsy, tumors, injuries, inflammatory and vascular diseases of the brain are diagnosed using EEG. Indications for rheoencephalography are seizures, convulsions, talking and wandering during sleep, as well as recent poisoning. EEG is the only test that can be performed even if the patient is unconscious.
REG (electroencephalography) helps to identify the causes of vascular pathologies of the brain. Thanks to this study, it is possible to study cerebral blood flow. The study is carried out by passing a weak high-frequency current through the brain tissue. Recommended for high or low blood pressure and migraines. The procedure is painless and safe.
ENMG is the latest popular study. This is electroneuromyography, through which lesions affecting the neuromotor peripheral apparatus are examined. Indications are myosthenia, myotonia, osteochondrosis, as well as degenerative, toxic and inflammatory diseases.
Year of issue: 2000
Genre: Physiology
Format: DOC
Quality: OCR
Description: The human brain is extremely complex. Even now, when we know so much about the brain not only of humans, but also of a number of animals, we are apparently still very far from understanding the physiological mechanisms of many mental functions. We can say that these issues are just included in the agenda of modern science. First of all, this concerns such mental processes as thinking, perception of the surrounding world and memory, and many others. At the same time, the main problems that will have to be solved in the 3rd millennium have now been clearly defined. What can modern science present to a person interested in how the human brain functions? First of all, there are several systems “working” in our brain, at least three. Each of these systems could even be called a separate brain, although in a healthy brain each of them works in close cooperation and interaction. What kind of systems are these? These are the activating brain, the motivational brain and the cognitive, or cognitive (from the Latin Cognitio - knowledge), brain. As already indicated, one should not understand that these three systems, like nesting dolls, are nested within one another. Each of them, in addition to its main function, for example the activating system (brain), is both involved in determining the state of our consciousness, sleep-wake cycles, and is an integral part of the cognitive processes of our brain. Indeed, if a person’s sleep is disturbed, then the process of studying and other activities is impossible. Violation of biological motivations may be incompatible with life. These examples can be multiplied, but the main idea is that the human brain is a single organ that ensures vital activity and mental functions, however, for convenience of description, we will highlight the three blocks indicated above.
"Fundamentals of Neurophysiology »
WHY DOES A PSYCHOLOGIST NEED TO KNOW THE PHYSIOLOGY OF THE BRAIN?
CURRENT ADVANCES IN HUMAN BRAIN RESEARCH
NEUROBIOLOGICAL APPROACH TO STUDYING THE HUMAN NERVOUS SYSTEM
PHYSIOLOGY OF THE HUMAN BRAIN
DEVELOPMENT OF THE HUMAN NERVOUS SYSTEM
FORMATION OF THE BRAIN FROM FERTILIZATION TO BIRTH
CELL - BASIC UNIT OF NERVOUS TISSUE
GLIA MORPHOLOGY AND FUNCTION
NEURON
NEURON EXCITATION
EXCITATION
SYNAPSE
MEDIATORS OF THE NERVOUS SYSTEM
OPIATE RECEPTORS AND BRAIN OPIOIDS
ACTIVATING SYSTEMS OF THE BRAIN
PHYSIOLOGICAL MECHANISMS OF SLEEP
MENTAL ACTIVITY DURING SLEEP
PHYSIOLOGICAL MECHANISMS OF REGULATION OF VEGETATIVE FUNCTIONS AND INSTINCTIVE BEHAVIOR
PERIPHERAL PART OF THE AUTONOMIC NERVOUS SYSTEM
VEGETATIVE CENTERS OF THE BRAINSTEM
LIMBIC SYSTEM OF THE BRAIN
PHYSIOLOGY OF HYPOTHALAMUS
CONTROL OF ENDOCRINE SYSTEM FUNCTIONS
BODY TEMPERATURE REGULATION
CONTROL OF WATER BALANCE IN THE BODY
REGULATION OF EATING BEHAVIOR
REGULATION OF SEXUAL BEHAVIOR
NERVOUS MECHANISMS OF FEAR AND RAGE
PHYSIOLOGY OF THE AMYNDALA
PHYSIOLOGY OF THE HIPPOCAMPUS
NEUROPHISIOLOGY OF MOTIVATION
STRESS
COGNITIVE BRAIN
PHYSIOLOGY OF MOVEMENTS
REFLECTOR LEVEL OF MOVEMENT ORGANIZATION
PHYSIOLOGY OF THE CEREBELLUM
NEUROPHYSIOLOGY OF THE STRIATAL SYSTEM
DOWNWAY MOTOR CONTROL SYSTEMS
PHYSIOLOGY OF SENSORY SYSTEMS
NEUROPHISIOLOGY OF THE VISUAL SYSTEM
NEUROPHISIOLOGY OF THE AUDITORY SYSTEM
NEUROPHISIOLOGY OF SOMATOSENSOR SYSTEM
NEUROPHISIOLOGY OF SENSORY PATHWAYS OF THE SPINAL CORD
PHYSIOLOGY OF THE TRIGEMINAL NERVE
Neurophysiology of the olfactory system
NEUROPHISIOLOGY OF TASTE
HIGHER FUNCTIONS OF THE NERVOUS SYSTEM
ASYMMETRY OF THE HUMAN HEMISPHERES
TEMPORAL PARTS OF THE BRAIN AND ORGANIZATION OF AUDITORY PERCEPTION
OCCIPITAL BRAIN AND VISUAL PERCEPTION
PARTICIPATION OF THE CORTEX IN THE ORGANIZATION OF VISUAL SPATIAL SYNTHESIS
FRONTAL LOBE OF THE BRAIN AND REGULATION OF HUMAN MENTAL ACTIVITY
Fundamentals of neurophysiology and GNI
REGULATORY SYSTEMS OF THE ORGANISM AND THEIR INTERACTION
Regulation of organ functions is a change in the intensity of their work to achieve a useful result according to the needs of the body in various conditions of its life. It is advisable to classify regulation according to two main characteristics: the mechanism of its implementation (nervous and humoral) and the time of its activation relative to the moment of change in the value of the body’s regulated constant. There are two types of regulation:by deviation and advance.
Regulation is carried out according to several principles, the main of which are the principle of self-regulation and the systemic principle. The most general of them is the principle of self-regulation, which includes all the others. The principle of self-regulation is that the body, using its own mechanisms, changes the intensity of the functioning of organs and systems according to its needs in various living conditions. So, when running, the activity of the central nervous system, muscular, respiratory and cardiovascular systems is activated. At rest, their activity decreases significantly.
NERVOUS REGULATION MECHANISM
There are several concepts in the literature that reflect the types and mechanism of influence of the nervous system on the activity of organs and tissues. It is advisable to distinguish two types of influences of the nervous system on organs - triggering and modulating (corrective).
A. Trigger influence. This influence causes the activity of an organ that is at rest; the cessation of the impulse that caused the activity of the organ leads to its return to its original state. An example of such an influence is the triggering of the secretion of the digestive glands against the background of their functional rest; initiation of contractions of resting skeletal muscle upon receipt of impulses from motor neurons of the spinal cord or from motor neurons of the brain stem along efferent (motor) nerve fibers. After the cessation of impulses in the nerve fibers, in particular in the fibers of the somatic nervous system, muscle contraction also stops - the muscle relaxes.
B. Modulating (corrective) influence. This type of influence changes the intensity of the organ’s activity. It extends both to organs whose activity is impossible without nervous influences, and to organs that can operate without the triggering influence of the nervous system. An example of a modulating effect on an already functioning organ is the strengthening or suppression of the secretion of the digestive glands, the strengthening or weakening of skeletal muscle contraction. An example of the modulating influence of the nervous system on organs that can work automatically is the regulation of heart activity and vascular tone. This type of influence can be multidirectional using the same nerve on different organs. Thus, the modulating effect of the vagus nerve on the heart is expressed in the inhibition of its contractions, but the same nerve can have a triggering effect on the digestive glands, resting smooth muscle of the stomach, and small intestine.
The modulating influence is carried out:
by changing the nature of electrical processes in excitable cells of the organ of excitation (depolarization) or inhibition (hyperpolarization);
due to changes in the blood supply to the organ (vasomotor effect);
By changing the intensity of metabolism in the organ (trophic effect of the nervous system).
The idea of the trophic action of the nervous system was formulated by I.P. Pavlov. In an experiment on dogs, he discovered a sympathetic branch going to the heart, irritation of which causes an increase in heart contractions without changing the frequency of contractions (Pavlov's enhancing nerve). Subsequently, it was shown that irritation of the sympathetic nerve actually enhances metabolic processes in the heart. Developing the idea of I.P. Pavlov, L.O. Orbeli and A.G. Ginetsinsky in the 20s of the XX century. discovered the phenomenon of increased contractions of a tired skeletal muscle when the sympathetic nerve going to it is irritated(Orbeli-Ginetzinsky phenomenon).
MEDIATORS AND RECEPTORS OF THE CNS
The mediators of the central nervous system are many chemical substances that are structurally heterogeneous (about 30 biologically active substances have been found in the brain). According to their chemical structure, they can be divided into several groups, the main of which are monoamines, amino acids and polypeptides. A fairly widespread mediator is acetylcholine.
A. Acetylcholine. Found in various parts of the central nervous system, it is known mainly as an excitatory transmitter: in particular, it is a mediator of α-motoneurons of the spinal cord innervating skeletal muscles. With the help of acetylcholine, α-motoneurons transmit excitation along the collaterals of their axons to the inhibitory Renshaw cells. M- and N-cholinergic receptors were found in the reticular formation of the brain stem and in the hypothalamus. When acetylcholine interacts with the receptor protein, the latter changes its conformation, resulting in the opening of an ion channel. Acetylcholine exerts its inhibitory effect through M-cholinergic receptors in the deep layers of the cerebral cortex, in the brain stem, and caudate nucleus.
B. Monoamines. They release catecholamines, serotonin and histamine. Most of them are found in significant quantities in neurons of the brain stem; in smaller quantities they are found in other parts of the central nervous system.
Catecholamines ensure the occurrence of processes of excitation and inhibition, for example, in the diencephalon, substantia nigra, limbic system, striatum.
With the help of serotonin, excitatory and inhibitory influences are transmitted in neurons of the brain stem, and inhibitory influences are transmitted in the cerebral cortex. Serotonin is found mainly in structures related to the regulation of autonomic functions. There is especially a lot of it in the limbic system, the raphe nuclei. Enzymes involved in the synthesis of serotonin were identified in the neurons of these structures. The axons of these neurons pass through the bulbospinal tract and terminate on neurons of various segments of the spinal cord. Here they contact the cells of preganglionic sympathetic neurons and interneurons of the substantia gelatinosa. It is believed that some, or perhaps all, of these so-called sympathetic neurons are serotonergic neurons of the autonomic nervous system. Their axons, according to some authors, go to the organs of the digestive tract and stimulate their contraction.
Histamine is found in fairly high concentrations in the pituitary gland and the median eminence of the hypothalamus. In other parts of the central nervous system, the level of histamine is very low. Its mediator role has been little studied. There are H1- and H2-histamine receptors. H1 receptors are present in the hypothalamus and are involved in the regulation of food intake, thermoregulation, and the secretion of prolactin and antidiuretic hormone. H2 receptors are found on glial cells.
B. Amino acids. Acidic amino acids(glycine, γ-aminobutyric acid) are inhibitory transmitters at CNS synapses and act on inhibitory receptors (see section 4.8).Neutral amino acids(α-glutamate, α-aspartate) transmit excitatory influences and act on the corresponding excitatory receptors. It has been suggested that glutamate may be a mediator of afferents in the spinal cord. Receptors for glutamic and aspartic amino acids are present on cells of the spinal cord, cerebellum, thalamus, hippocampus, and cerebral cortex.It is believed that glutamate- the most common neurotransmitter of the central nervous system.
D. Polypeptides. INAt CNS synapses they also perform a mediator function. In particular, substance P is a mediator of neurons that transmit pain signals. This polypeptide is especially abundant in the dorsal roots of the spinal cord. This gave rise to the assumption that substance P may be a mediator of sensitive nerve cells in the area of their switching to interneurons. Substance P is found in large quantities in the hypothalamic region. There are two types of receptors for substance P: receptors of the SP-P type, located on the neurons of the cerebral septum, and receptors of the SP-E type, located on the neurons of the cerebral cortex.
Enkephalins and endorphins are neurotransmitters that block pain impulses. They realize their influence through the corresponding opiate receptors, which are especially densely located on the cells of the limbic system; There are also many of them on the cells of the substantia nigra, the nuclei of the diencephalon and solitary tract, and they are present on the cells of the locus coeruleus and the spinal cord. Their ligands are )