Concepts of the nervous system. Tishevskoy I.A.

CONCEPTS OF THE NERVOUS SYSTEM

Basic concepts nervous system. Morphofunctional features of the spinal cord.

NEUROLOGY is the science that studies the nervous system.

Functions of the nervous system:

1. The nervous system provides the interconnection of individual organs and systems, harmonizes and combines their functions. Thanks to this, the body works as a whole.
2. The CNS communicates with the body external environment, provides individual adaptation to the external environment.
3. The brain is the organ of mental activity. Here are the processes of consciousness, thinking, memory.

CLASSIFICATION OF THE NERVOUS SYSTEM

1. Topographic (anatomical):

CNS - brain and spinal cord

· Peripheral - SMN, CN, nerve nodes, nerve endings, plexuses.

1. Physiological:

• Somatic - innervates the skin, skeletal muscles, sensory organs.
• Vegetative or autonomous - innervates everything internal organs and ZhVS (i.e. organs of plant life hence the name)

a. sympathetic

b. Parasympathetic

CONCEPTS OF THE NERVOUS SYSTEM

The structural unit of the nervous system is a neuron (see nervous tissue), as well as nerve fibers, endings, and sheaths.

Neurons that release acetylcholine are called cholinergic, and neurons that release norepinephrine are called adrenergic.

The brain and spinal cord are built from a huge number of neurons and nerve fibers.

The accumulation of neuron bodies is called gray matter , it performs a reflex function.

white matter called the accumulation of nerve fibers that are collected in bundles. Bundles of nerve fibers connect some parts of the central nervous system with others and perform a conductive function.

Nerve fibers- These are the processes of nerve cells covered with a myelin sheath.

White and gray matter are located unequally in different parts of the central nervous system.

A continuous layer of gray matter on the surface hemispheres and the cerebellum is called bark .

Beneath the cortex is white matter and nuclei.

Nuclei - These are separate accumulations of gray matter in white. They act as a center that regulates the functions of organs.

ganglion is an accumulation of bodies of neurons outside the CNS. Nerves can be:

1. sensitive
2. vegetative

Reflex time ( The latent period is the time elapsed from the moment the stimulus is applied to the response to it.

Most of reflex time is spent on conducting excitation through the nerve centers - the central reflex time (due to synaptic delay).

The fewer neurons in the arc, the shorter the reflex time.

The greatest is the time of vegetative reflexes.

receptive reflex field - this is the anatomical region, upon stimulation of which this reflex is evoked (pupil constriction reflex when the retina is illuminated).

Nerve center is a complex of neurons that regulate some function. Nerve centers are: 1. primary

Neurophysiology determines the study of the central nervous system and its function, connects to translational science, neurology, neurobiology, psychology, neuroanatomy, electrophysiology, cognitive sciences.

As a science, neurophysiology deals with the study, diagnosis and treatment of all categories of diseases accompanied by the central, peripheral and autonomic nervous systems.

Neurophysiology is the union of neurology and physiology that studies the functioning of the nervous structure. Neurology is a special branch of medical science that deals primarily with disorders in the central nervous system.

The goal of neurophysiology is to understand how the brain works to advance treatments for diseases and disorders of the nervous system.. This type of research requires investigation of the complex functions of structure at all levels of the living. Due to the fact that people cannot be used for this work, neuroscientists most often use animals. Scientists use animals to figure out how diseases and their potential therapies affect the entire body. They conduct experimental procedures with various alternative methods.

Glossary of Neurophysiology

Neurosurgery

Neurosurgery - a branch of medicine that deals with the prevention, diagnosis, treatment and rehabilitation of disorders that affect any part of the nervous structure, including the functioning of the brain, spinal cord, peripheral nerves and extracranial vessels of the head.

Neurological disorders

Neurological disorders are diseases of the main organ of the central nervous system, spine and nerves. There are over 600 diseases of the nervous system, such as brain tumors, epilepsy, Parkinson's disease, stroke, as well as less familiar ones, such as frontotemporal dementia.

Traumatic brain injury

Traumatic brain injury (TBI) is a complex of injuries with a wide range of symptoms and physical damage. A head injury is usually the result of a hard blow or push to the head or body. The object enters the skull like a bullet or a splintered piece of the skull, which can also cause a head injury.

limbic system

limbic system - a complex set of structures that lies on either side of the thalamus of the brain. It includes the hypothalamus, hippocampus, amygdala, and several other nearby parts. It seems to be primarily responsible for our emotional life and has a lot to do with the formation of memories.

Spinal cord

Spinal cord is the most important structure between body and head. The spinal cord extends from the foramen magnum, where it is continuous and oblong at the level of the first or second lumbar vertebrae. It is a vital connection between the head and the body and from the body to the main organ of the central nervous system.

Neuroendocrinology

Neuroendocrinology studies the interaction of the nervous and endocrine systems, including biological features cells participating and exchanging information. The nervous and endocrine systems often work together in a process called neuroendocrine integration. Neuroendocrinology tracks the regulation of the physiological processes of the human body.

Pituitary is an important gland in the body and is often referred to as the master gland because it controls a number of other hormonal glands. The pituitary gland is usually about the size of a pea and consists of two parts - an anterior part, called the anterior pituitary gland, and a posterior part, called the posterior pituitary gland.

Hypothalamus

Hypothalamus - This is a section of the main organ of the central nervous structure, which is responsible for the production in the body of the most important hormones, chemicals that help control various cells and organs. Hypothalamic hormones regulate physiological functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and the release of other hormones in the body.

neural model

neural regions model the mathematical foundations of machine learning, which combine the ideas of neural networks, logic, and model recognition. It is also referred to as simulation field, simulation field theory, maximum likelihood of artificial neural networks.

hippocampus

hippocampus is part of the main organ of the central nervous system, which is involved in the formation of memory, ordering and storage. This is the structure of the limbic system, which is especially important in the formation of new memories and the connection of emotions and feelings, such as smell and sound, to memories. The hippocampus is shaped like a horseshoe. This is a paired structure, one part of the hippocampus is located in the left hemisphere, and the other in the right hemisphere.

Methods and tasks of human brain neurophysiology

Neurophysiology also plays a role in the management of people who have brain disease, viral encephalitis, meningitis, stroke or dementia. This science conducts research in special environments or departments.

Neurophysiology is an interdisciplinary field that encompasses research in molecular, cellular, and systemic neurophysiology, functional morphology, neuropharmacology, and neurochemistry. Neuromuscular physiology, neural mechanisms of higher nervous activity and behavior, medical aspects of neurophysiology and modeling of neural functions are also studied by this science.

Research includes:

• EEG (electroencephalography) is a recording of electrical activity and brain activity from the scalp, which is mainly used in diagnosing epilepsy and monitoring people with this condition.
• Evoked potentials are the analysis of bioelectrical signals of the brain in response to certain stimuli, such as flashing lights or sounds. Evoked potentials are used in the diagnosis of various diseases, including multiple sclerosis and eye diseases like night blindness.
• EMG (electromyography) - evaluates the function of nerves and muscles in the body. Electromyography is used in conditions that affect nerve and muscle function, including myasthenia gravis, a disease of Morton's neuroma (thickening of the foot nerve). It is more common in women due to wearing high heels.

The science of studying how the brain works

Weighing less than a kilogram and a half, the human says it is the most complex organ of any living primate.

But also, like most, it is virtually identical among mammals and bears major similarities in structure, function, and brain function to those species most closely related to humans on the tree of life. However, even the nervous system from the simplest organisms offers clues about the function and workings of the human brain. Researchers are also studying to identify key differences in the main organ of the central nervous system that endow humans with unique cognitive abilities and abstraction.

Neuroscientists study various animal models from fish to songbirds. The simplicity of the nervous system of the Ascaris nematode (roundworm) allowed scientists to trace all of its nerve connections. This understanding could lead to an understanding of the connections in the workings of the human brain. Researchers are also studying chemicals in the animal kingdom in hopes of finding new drugs.

Animal brains come in a wide variety of shapes and sizes, but size is a poor indicator of intelligence. The giraffe's brain is almost as big as the human brain, but the giraffe's intelligence is notoriously low.

It is not the size of the main organ of the central nervous system that matters, but the number of neurons and where they are located. The human cortex, the shrunken organ responsible for language, thought and information processing, contains 16 billion neurons, more than any other animal.

Obviously, this explains human enhanced cognitive abilities. Scientists are studying other animals to determine how dense areas of the main organ of the central structure of neurons can similarly affect the function and functioning of the brain.

The nervous system (Systema nervosum) is one of the leading integrating systems of the body, and together with the endocrine and cardiovascular systems unites the body into a single whole. According to Pavlov I.P., the body is not a mechanical sum of its constituent parts, but a complex one, dynamic system, all parts of which are interconnected and interdependent. The body is in constant and close contact with the external environment. In the process of life, the body adapts to environmental conditions. The level of its adaptability to the external environment is controlled by the nervous system. Thus, Systema nervosum provides the connection of the body with the external environment, controls the work of all organs and connects all parts of the body into a single whole. It coordinates blood circulation, lymph flow, metabolic processes, which in turn affect the state of the nervous system. Pavlov I.P. wrote: “The activity of the nervous system is directed, on the one hand, to the unification, integration of all parts of the body, on the other hand, to the connection of the body with the environment, to balancing the systems of the body with the outside world”

The nervous system works on the principle of feedback, i.e. an impulse along its peripheral part goes to the brain, and from the brain along the same peripheral part to the working organ. It must be remembered that any response to irritation will be movement, therefore the nervous system develops in parallel with the musculoskeletal system.

The science that studies the nervous system is called Neurologia.

Philo- and ontogeny of the nervous system. In the process of historical development, the nervous system goes through a series of successive stages:

I stage - Humoral stage. The connection of the organism with the environment is carried out through a specific fluid, which is both outside and inside it. This stage is typical for unicellular organisms.

Stage II - Diffuse stage. The connection of the organism with the external environment is carried out with the help of neurons, the processes of which, in contact with each other, form a network. This network permeates the entire body of a multicellular organism, therefore, when irritated, the entire body contracts. The mesh type of the nervous system is characteristic of the intestinal (hydra, jellyfish, polyps).

A reflection of this stage in higher vertebrates is the parasympathetic part of the autonomic nervous system.

Stage III - Ganglion stage. At this stage, neurons form clusters (ganglia), which are located not randomly, but segmentally, metamerically and are connected by nerve processes. Irritation is already localized within one segment. The ganglionic type of the nervous system is characteristic of higher worms, arthropods. A reflection of this stage in higher vertebrates is the sympathetic part of the autonomic nervous system.

Stage IV - The tubular stage is accompanied by a concentration of nerve ganglia in the form of a neural tube, inside of which there is a cavity. This structure of the nervous system is characteristic of all chordates - from the lancelet to mammals and birds.

Stage V - The next stage is associated with the improvement of the sense organs, the progressive development of the anterior part of the neural tube and the formation of the brain (i.e., encephalization occurs). First, one cerebral vesicle is formed, then the expansion is laced with two constrictions to form 3 primary cerebral vesicles. Subsequently, the 1st and 3rd are again divided into two departments. Thus, 5 brain bubbles are formed, from which 5 parts of the brain subsequently develop. The cavities of the cerebral vesicles are converted into ventricles, inside which cerebrospinal fluid (CSF) circulates. Liquor provides neurons with nutrients and oxygen, acting as an intermediary between blood and nervous tissue. Thus, the stimulus for the development of the brain was the further improvement of the receptor apparatus of animals (sense organs).

As for the spinal cord, the stimulus for its development was the motor activity of animals. This first led to the formation of the trunk brain, which in the process of development was replaced by the spinal cord with spinal nerves extending from it to all segments of the body.

In ontogenesis, the nervous system develops from the ectoderm, in which the neural plate first stands out, neural folds appear in it, which, closing, form the neural tube.

At the cranial end of the neural tube, 3 cerebral vesicles first appear, and then, by dividing 2 of them, 5 cerebral vesicles. From these 5 brain bubbles, 5 parts of the brain are subsequently formed.

From the caudal end of the neural tube, the spinal cord develops, which at the beginning of embryogenesis corresponds to the length of the spinal canal, and then occupies only a part of it, as it grows more slowly than the spinal column.

A section of knowledge is devoted to the study of the nervous system, which in Russia and European countries is called neurology, that is, the study of the nervous system, and in America - neurobiology. This section is represented by several sciences that study the nervous system on different levels and using different methods.

The first group of sciences that study the morphology of the nervous system and its constituent elements includes:

1. Anatomy (Greek "anatemno" - cut) is the most ancient of the sciences of the structure of the human body. The section of this science - the anatomy of the central nervous system - studies the morphology of the nervous system at the organ level.

2. Histology of the CNS (Greek "histos" - tissue) studies the structure of the nervous system at the tissue and cellular levels.

3. Cytology (Greek "cytos" - cell) studies the structure of neurons and glial cells at the cellular and subcellular levels.

4. Biochemistry and molecular biology study the structure of neurons and auxiliary cells of the nervous system at the subcellular and molecular levels.

The following group of disciplines studies the functions of the nervous system with the help of experiments and modeling of the processes occurring in it:

5. The physiology of the central nervous system explores the general patterns of functioning of nerve cells, individual structures of the central nervous system and the entire nervous system as a whole.

6. The physiology of analyzers (sensor systems) studies the work of structures that perceive and process information.

Of the sciences of applied importance, knowledge of the anatomy of the central nervous system is necessary, first of all, in medicine (7). The functions of the central nervous system and their relationship with various parts and structures of the brain are being studied by clinicians observing sick people ( FOOTNOTE: This method of studying the role of various brain structures is called "bringing function out of dysfunction.") A particularly large contribution was made by doctors of such medical specialties as neuropathology and neurosurgery, otolaryngology, and psychiatry.

Neurobiology is a branch of biology and is the science of the structure, physiology and function of the brain.

In a literal sense, the term "neurobiology" is associated with the biology of the neurons (nerve cells) that make up the nervous system. However, the composition of the mammalian brain, in addition to neurons, includes a large number of diverse glial cells (called neuroglia), which occupy up to 90% of the brain volume. Neuroglial cells closely interact with neurons, ensuring their vital activity and normal functioning. In recent years, within the framework of neurobiology, the properties of neuroglial cells and their interaction with neurons in providing various functions have also been studied.

Abroad (and in recent years in Russia) the science of the brain is also called "neuroscience" (eng., neuroscience). Although formally this term should be translated as "the science of the nervous system", in terms of its content and the range of problems studied, the latter is equivalent to "neurobiology".

The beginnings of neurobiology date back to ancient times, however, its modern content is associated with research and discoveries since the middle of the 19th century. In the domestic scientific practice neurobiology arose at the intersection of the science of behavior and neurophysiology and as an independent discipline began to be mentioned recently.

The emergence and development of neuroscience

Development of the physicochemical foundations of neurobiology

The modern era of studying the structure and functions of the brain began with a number of discoveries in the 19th-20th centuries. Representatives and followers of the German physiological school (G. von Helmholtz, E. Dubois-Reymond, L. Herman, K. Ludwig, K. Bernard, J. Bernstein and others), founded in the first half of the 19th century. J.-P. Müller proved the electrical nature of signals in nerve fibers. In 1902, Yu. Bernshtein put forward the first membrane theory of nervous tissue excitation, in which he proclaimed the decisive role of potassium ions. We should pay tribute to a contemporary of J. Bernstein, E. Overton, who in 1902 made an important discovery, which is that sodium is needed to generate excitation in the nerve. However, the results of E. Overton remained without due attention from contemporaries. E. Dubois-Reymond and C. Bernard were the first to suggest that signals in the brain are transmitted using chemicals. Representatives Russian science also made a number of discoveries in electrophysiology. Thus, in 1896 V.Yu. V.V. Pravdich-Neminsky stood at the origins of electroencephalography: in 1913 he first recorded the electrical activity of the dog's brain from the surface of the skull. The first human electroencephalogram recording was obtained Austrian psychiatrist G. Berger in 1928. Representatives of the Russian physiological school founded by I.M. Sechenov in the 1860s, closely cooperated with the Europeans, constantly exchanging visits. Many young Russian scientists went to study in Europe (mainly in Germany), where they participated in joint research.

The basis of modern ideas about the structure and functions of the brain is the so-called "neural doctrine". At the end of the XIX century. the Italian neuroanatomist K. Golgi developed a method for staining nerve cells with silver chloride (later this method received his name) and found that the nervous tissue is an intricately intertwined network consisting of individual neurons. He suggested that the neurons in the network are interconnected by protoplasmic connections. However, the Spanish neuroanatomist S. Ramon y Cajal, using the Golgi method, proved that the nervous system consists of discrete cells (neurons) that are interconnected by specialized contacts. Subsequently, the English neurophysiologist C. Sherrington called the contacts between neurons synapses, which have since become key formations in the subsequent development of brain science.

Evidence of the chemical nature of synaptic transmission was obtained in parallel by representatives of two physiological schools - Kazan (founder - A.F. Samoilov, Russia, and then the USSR) and Cambridge (founder - C. Sherrington, Great Britain). The discoverers of the chemical nature of synaptic transmission all over the world are considered the German physiologist of Austrian origin O. Levy and the English scientist G. Dale. In 1921, O. Levy established the humoral (chemical) transmission of a nerve signal in the autonomic nervous system, namely, the inhibitory effect of the neurotransmitter acetylcholine on the heart rate in a frog during stimulation of the vagus nerve. However, the first evidence of humoral transmission was obtained as early as 1904 by T. Elliott, who demonstrated the release and action of adrenaline upon activation of peripheral nerves.

In violation of scientific ethics, the world scientific community is undeservedly silent about the discoveries of Russian scientists A.F. Samoilov and his students A.V. Kibyakov, M.A. Kiselev and I.G. Validov. A.F. Samoilov in the 1920s put forward ideas about the chemical nature of the transmission of excitation as from a nerve to skeletal muscle and between nerve cells throughout the nervous system. He owns priority studies of the phenomenon of synaptic delay and its temperature dependence in neuromuscular synapses, indicating the chemical nature of synaptic transmission. Thus, he extended the theory of chemical transmission of excitation from the region of the autonomic nervous system (works by O. Levy, G. Dale and T. Elliott) to the motor nerves. This message was first made at a meeting of the society of psychiatrists and neuropathologists in 1923. In addition, A.F. Samoilov with his student M.A. Kiselev discovered the chemical nature of inhibition processes. The results of this study were reported by him at the XII International Physiological Congress in Stockholm in 1926. A.V. Kibyakov in the early 1930s. demonstrated the neurotransmitter role of acetylcholine in the synapses of the cat's sympathetic ganglia. IG Validov proved the participation of calcium ions in the mechanism of synaptic transmission. He was also the first to prove the participation of intracellular calcium ions in the mechanism of synaptic transmission, which contribute to the conduction of excitation from the nerve to the muscle. The results of these studies were reported at the VII All-Union Physiological Congress in 1948 long before the publications of B. Katz and R. Milady in the mid-1960s, who carried out similar studies.

Cellular and molecular mechanisms of excitability of nerve cells were revealed in the studies of K. Cole, A. Hodgkin and E. Huxley. In 1939, K. Cole for the first time measured changes in ionic conductivity in the membrane of neuronal processes in invertebrates (giant squid axons) during its excitation, and in 1952 A. Hodgkin and E. Huxley for the first time recorded ion currents during excitation of the membrane and demonstrated sodium the potassium nature of action potentials in axon membranes. B. Katz made a number of important discoveries by studying the mechanisms of excitation of the neuromuscular synapse. An invaluable contribution to the study of the mechanisms of interneuronal signaling was made by J. Eccles. Ion currents during excitation of the membranes of the bodies of neurons in invertebrates and vertebrates were first registered at the Institute of Physiology of the Academy of Sciences of the Ukrainian SSR (USSR) in the early 1960s. under the leadership of Academician P.G. Kostyuk.

In 1979, J. Eccles suggested calling quick effects"fast" neurotransmitters ionotropic, meaning them direct impact on ion channels in the synaptic membrane, and the slow effects of "slow" neurotransmitters - metabotropic, suggesting that they are due to the initiation of metabolic processes (intracellular signaling pathways) in the cytoplasm of the postsynaptic neuron. Subsequently, P. Greengard described intracellular signaling pathways with the synthesis of a "second messenger", activated when dopamine binds to postsynaptic membrane receptors. These metabolic processes lead to a change in the permeability of ion channels that control the excitability of nerve cells. Later, many components involved in intracellular signaling pathways were discovered (various G-proteins, enzymes for the synthesis of second messengers, kinases, phosphatases, etc.). In 1976, B. Sakman and E. Neer published a study of single ion channels activated by acetylcholine in frog muscle fibers. Subsequent technological developments made it possible to study the activity of various single ion channels of cell membranes. In the past two decades, the widespread introduction of methods has made it possible to establish chemical structure many proteins involved in the processes of intercellular and intracellular signaling. The improvement of optical and electron microscopy methods using laser technologies has made it possible to study the macro- and microstructural foundations of the physiology of nerve cells and their organelles.

Achievements in the study of the physicochemical foundations of nervous processes certainly determined the development of various areas in the science of the brain and enriched ideas about its main functions: 1) processing information about the state of the body and the state of its environment by sensory systems; 2) organization and implementation of response actions by motor systems; 3) communication between the sensory and motor parts of the central nervous system by associative systems that provide higher-order functions (perception, attention, memory, cognition, emotions, thinking, and others).

Currently, neurobiology is a high-tech science that accumulates the achievements of modern chemistry, physics, mathematics and information technology.

Development of ideas about behavior

At the turn of the XIX-XX centuries. in parallel with the morphological and physiological studies of the nervous system, ideas about the mechanisms of behavior fell apart. In 1903 I.P. Pavlov proclaimed the theory of conditioned reflexes, which are newly acquired adaptive behavioral acts. Theory of I.P. Pavlova was based on the philosophical ideas of R. Descartes about the reflex nature of adaptive behavioral reactions and I.M. Sechenov about the reflex nature of mental processes. THEM. Sechenov believed that conscious and unconscious activities are of a reflex nature and that mental phenomena are due to physiological processes that can be studied by objective methods. Inspired by the ideas of I.M. Sechenov, I.P. Pavlov developed an objective physiological method studies of conditioned reflexes and used it to indirectly study internal processes that determine the "mental" origin of acquired adaptive vegetative reactions. With the name of I.P. Pavlova is associated with the beginning of an objective study of the mechanisms of behavior. The development of a conditioned reflex was interpreted by I.P. Pavlov as an association of two reflex arcs activated by two stimuli - unconditioned and conditioned, namely, two foci of excitation in the brain corresponding to these stimuli. For its time, such a physiological interpretation, undoubtedly, seemed to be advanced and opposed the method of subjective introspection used to analyze mental activity.

Parallel within the American school behaviorism(from English, behavior) developed ideas about instrumental behavior. Most typical representatives this direction are E. Thorndike, J. Watson and B. Skinner. Distinctive feature behaviorism is a descriptive nature of the study of instrumental behavioral reactions, not affecting, in contrast to Pavlovian interpretations, internal (albeit speculative with modern positions) mechanisms. Representatives of the new generation of behaviorists K. Lashley, E. Tolman and W. Hunter, who call themselves neobehaviorists, eventually turned to the neurophysiological interpretation of instrumental behavior. The physiological interpretation of the mechanisms of instrumental behavior with the involvement of conceptual reflex arcs was put forward by E. Konorsky, an outstanding student of I.P. Pavlova.

Among the reflex forms of behavior of I.P. Pavlov singled out relatively simple unconditioned reflexes that make up the innate basis of newly acquired behavioral acts. Congenital complex shapes behaviors (instincts) were originally studied by zoologists. In the middle of the XX century. instinctive behavior has become an object of scientific interest ethology, proclaimed by K. Lorenz and N. Tinbergen.

Within the framework of psychology, another branch of the science of behavior has arisen, which studies cognitive, or "reasonable" behavior, characteristic only of animals with a highly developed nervous system. As a result of research on the behavior of chimpanzees, W. Koehler described complex behavioral manifestations (insight (eng., insight), transfer, generalization), which do not require training and appear the first time. Such forms of behavior are manifested not only in higher primates, but also in other mammals and even in some birds and include the urgent solution of new tasks - different types elementary logical tasks, instrumental activity in a new situation. The ability of animals to solve elementary logical problems was investigated by corresponding member. USSR Academy of Sciences L.V. Krushinsky, who developed ideas about elementary rational activity animals. He established that the possibility of manifestation of elementary rational activity in animals depends on the complexity of the organization of the brain. L.V. Krushinsky considered the cognitive abilities of some animals as phylogenetic prerequisites for higher mental functions in humans.

Even C. Sherrigton, on the basis of his experiments, argued that reflexes are not reduced to the activation of the so-called reflex arcs, but should be considered as an integrated activity of the organism as a whole. PC. Anokhin put forward the concept of a “functional system”, which explained an adaptive behavioral act as a result of the integration of private nervous and humoral mechanisms that enter into a complex coordinated dynamic interaction. PC. Anokhin extended the principle of "functional system" to the structure of any purposeful behavior.

With the development of neurophysiological methods in the 1950-60s. they have become widely used to study the neural mechanisms of behavior. Registration of the total electrical activity of the brain and individual neurons gave a new impetus to the development of ideas about the mechanisms of behavior. The integration of various scientific fields, as well as the development of new methods in neurobiology, have significantly enriched the methodological base for studying the mechanisms of behavior. The discovery of the phenomenon synaptic plasticity opened up new opportunities for researching the key property of the central nervous system that underlies learning - memory. In the early 1970s. T. Bliss and T. Lemo discovered changes in the efficiency of synaptic transmission in the synapses of the hippocampus of the rabbit. Subsequently, such modifications of synaptic transmission were also demonstrated in the synapses of other mammalian brain structures. Similar phenomena have also been found in the simple nervous systems of invertebrates, in particular, in mollusks (works by E. Kandel). The revealed phenomena of synaptic plasticity in their temporal dynamics were associated with ideas about short-term And long-term memory. Thus, ideas about memory and its organization have found their neurophysiological interpretation. Subsequently, synaptic plasticity models were used in studies of behavioral mechanisms as cellular analogues of memory and learning, confirming the theoretical predictions of the neurophysiologist D. Hebb of the late 1940s.

Modern neurobiology as an integrative science

Currently, neurobiology is an interdisciplinary science that includes some scientific areas in psychology, medicine, mathematics, computer science, physics, linguistics and philosophy. Within the framework of modern neurobiology, a wide range of problems is studied, including various approaches to the study of molecular, ontogenetic, structural, functional, evolutionary, medical, and cybernetic aspects of the central nervous system and its key role in controlling the behavior of organisms. These problems can be studied using analytical tools of the whole complex. biological sciences including biophysics, molecular and cell biology, genetics, embryology, anatomy and physiology, behavioral biology, and psychology. The technologies used in neuroscience are extremely diverse - from biophysical and molecular methods for studying individual cells, ion channels, membrane receptors, cell organelles to visualization of perceptual, integrative and motor processes of the whole brain using magnetic resonance and positron emission tomography. Recent theoretical advances in neuroscience have given impetus to the study of neural-like networks, which are the basis for approaches to create artificial intelligence. The task of neurobiology is the integration of various information obtained at different levels of analysis of the work of the central nervous system into a consistent understanding of its structure and functions. Expanding the range of neuroscience problems involving a large number scientists from a wide variety of scientific fields in the study of the work of the brain contributed to the creation of special international scientific communities. For example, in 1960 was founded International Organization Brain Studies (International Brain Research Organization), in 1968 - the European Society for the Study of the Brain and Behavior (European Brain and Behavior Society), in 1969 - the Society for Neuroscience of the USA (Society for Neuroscience, USA).

Fundamentals of modern neuroscience

In the second half of the XX century. Research on the nervous system has received a significant boost from revolutionary advances in molecular and cellular physiology, neurophysiology, and information technology. As a result, our knowledge of the microanatomy and physiology of neurons, molecular processes in their cytoplasm and organelles, as well as interneuronal communications has been significantly enriched. However, the role of neural networks in providing intelligence, thinking, consciousness, emotions, organizing purposeful behavior and a number of other manifestations of the psyche remains completely unknown.

Many morphological and functional types neurons and glial cells. Despite the fact that glial cells were first described by R. Virchow as early as the middle of the 19th century, for many decades the functions of these cells remained little studied, and they were attributed only to an auxiliary role. At present, our understanding of the structure and functions of glia has significantly expanded. It turned out that glial cells have many properties that are inherent in neurons. The nervous system is formed by networks that consist of a variety of neurons and glial cells. These neural networks constitute the primary modules of the nervous system that process specific types of information. These neural modules form discrete anatomical formations in the brain that perform specific functions. Neurobiology is called upon to investigate the functioning of such modules at several levels - molecular, cellular, systemic and behavioral.

On the molecular level within the framework of neurobiology, they study (1) intracellular mechanisms of the synthesis of signaling molecules; (2) intracellular cascades initiated by signaling molecules; (3) mechanisms of integration of intracellular events leading to neuron activation with subsequent release of neurotransmitters. At this level of research, methods of molecular biology and genetics study the processes of development and death of neurons and the influence of genetic factors on the biological functions of neurons. Of particular interest are the mechanisms that alter the morphology, molecular identity, and physiological properties of neurons, and how such changes subsequently lead to modifications of various behaviors. On the other hand, no less important are the mechanisms that change the functions of the neuron with the individual experience of the organism, and how these changes determine the processes at the physiological and behavioral levels.

On the cellular level, they study the fundamental physiological and electrochemical mechanisms of processing various signals, which are various chemical and electrical effects, as well as the mechanisms of transformation of these signals addressed to the membranes of dendrites, bodies and axons of neurons. A peculiar "nerve code" of each neuron is the pattern of electrical signals generated by it and neurotransmitter specificity. Another important area of ​​neuroscience in cellular level is a study of the development of the nervous system. Challenges in this area include: (1) regional subdivision of developing neural tissue with subsequent formation of specialized structures; (2) stem cell proliferation; (3) their differentiation into different types neurons and glial cells; (4) neuronal migration; (5) development of processes (dendrites and axons); (6) trophic interaction of the cells of the nervous system; and (7) formation of synaptic contacts.

On the systemic level, they study how the anatomical and functional neuronal formations formed during development are specialized to perform certain functions, such as reflexes, sensory signal integration, motor coordination, regulation of circadian rhythms, emotional reactions, learning, memory, and many others. It is still an unsolvable mystery how some neurons become sensitive to visual and others to auditory signals, and how these neurons give us the ability to subjectively experience light and sound. Such problems were posed in the middle of the 19th century. J.-P. Müller in his "theory of specific energy". Within the framework of neuroethology, the specificity of neuronal populations in providing certain behavioral acts in animals is studied, and within the framework of neuropsychology, the role of various cortical zones in providing mental functions in humans is studied. Within the framework of neurobiology, the mechanisms of interaction of the nervous system with the endocrine and immune systems are also being studied.

On the cognitive(cognitive) level, the neural mechanisms in providing cognitive activity in a person. For this, modern methods of visualizing the state of the brain (magnetic resonance and positron emission tomography), as well as traditional electroencephalography in solving complex mental problems, are widely used. The purpose of such studies is to establish a correspondence between the activated areas of the brain and mental processes.

Neurobiology and medicine. Such medical areas as neurology, neurosurgery, neuropathology and psychiatry study disorders in the functioning of the nervous system. Various diseases are natural models of brain dysfunctions, the study of which contributes to the development of ideas about the functions of the brain and ways to treat these diseases.

Neurobiology and humanitarian sciences . Neurobiology is closely related to psychology and sociology. Advances in neural network research allow the use of neural-like models in economics, for solving artificial intelligence problems and decision making, and in the social sciences. The achievements of neurobiology are also in demand in philosophy, which sets the task of comprehending the purpose of the mind. Philosophy tries to explain the essence of the mental by comparing the philosophical dyad "thought-idea" and the neurobiological dyad "structure-function".

Main directions of neuroscience

Currently, there are several main areas of research in neuroscience. However, such a subdivision is conditional, and in real scientific practice the areas of interest overlap significantly.

Molecular and Cellular NeuroscientistsI. The subject of research are: the ultrastructure of neurons and glial cells, protein metabolism, synapses, ion channels, action potentials and postsynaptic potentials, neurotransmitters, intracellular signaling pathways, interaction of the nervous and immune systems.

Neurobiology of behavior. The subject of research is: behavioral genetics, biological psychology, regulation of circadian rhythms, neuroethology, hypothalamic-pituitary mechanisms of behavior regulation, maintenance of homeostasis, sexual dimorphism, sensory systems, motor control systems, hormonal regulation, dependence from substances (for example, drugs and alcohol).

Systems neuroscience. The subject of research is: physiology of sensory systems, analysis of complex sensory-specific features, physiology propulsion systems, sensory integration, pain and its sensation, spontaneous and evoked electrical activity, functional states (sleep, wakefulness, etc.), maintenance of homeostasis, motivation, nonspecific activation ( arousal), Attention.

Developmental neuroscience. The subject of research are: cell proliferation in the brain, neurogenesis, formation of neuronal processes, neuron migration, growth factors, neurotrophins, apoptosis and anti-apoptosis, synaptogenesis.

Cognitive neuroscience. The subject of the research is: voluntary selective attention, consciousness (understanding), cognitive control, cognitive genetics, decision making, motivations and emotions, language functions, memory, activity, perception, social aspects.

Theoretical and Computational Neurobiology. The subject of the research is: modeling the generation of nerve impulses (for example, action potentials in the Hodgkin-Huxley model) and their conduction along nerve processes (cable theory), modeling synaptic interaction and synaptic integration, neural networks and their computer simulation, modeling learning (for example, Hebb's rule).

Neurobiology in Neurology and Psychiatry. The subject of the study are: autism, dementia, Parkinson's disease, cerebral apoplexy, peripheral neuropathy, traumatic lesions of the brain and spinal cord, autonomic disorders, psychosis, schizophrenia, depression, anxiety, addictions, memory disorders, sleep disorders.

Applied neuroscience. The subject of research are: sensory and motor neuroprostheses, biofeedback, brain-computer interface.

neurolinguistics. The subject of the research is: language functions, expression of oral speech, language acquisition, perception of oral and written speech, analysis of syntactic constructions.

Neuroimaging(English, neuroimaging). The subject of the research are: structural and functional visualization of the brain.

The listed directions do not exhaust the range of problems studied in the framework of modern neurobiology. Some of the directions overlap to a large extent with each other.

Future of neuroscience (unsolved problems)

Despite certain advances in neurobiology, some important problems still remain unresolved and require further research. The most distant prospects for problem solving concern cognitive processes. Before modern neurobiology, questions about the neural mechanisms of consciousness, sleep, perception, learning and memory, neuroplasticity, and decision making remain unresolved. Many unresolved questions concern the development and evolution of the nervous system. The neuronal mechanisms of the occurrence of some mental illness(eg, obsessive-compulsive disorder, schizophrenia), Parkinson's disease, Alzheimer's disease, addictions.

Listed below are just 10 mysterious properties of the brain that need to be unraveled in the future:

1. How is information encoded in patterns of neural activity?

2. How is information stored and retrieved from memory?

3. What does the background electrical activity of the brain reflect?

4. How does the brain simulate the future?

5. What are emotions?

6. What is intelligence?

7. How is time represented in the brain?

8. Why does the brain sleep, and what are dreams?

9. How do the specialized systems of the brain interact with each other?

10. What is consciousness?

Neuroscientists constantly work closely with scientists from other scientific fields, and the success of solving many of the problems facing neuroscience depends on this interaction.

Recommended reading

1. Blum F., Leizerson A., Hofstadter L., Brain, Mind, and Behavior, Mir, M., 1988.

2. Nichols J.G., Martin A.R., Wallas B.J., Fuchs P.A. From neuron to brain, LKI Publishing House, M., 2008.

3. Rose S., Memory Device, From Molecules to Consciousness, Mir, Moscow, 1995.

4. Hubel D. Eye, brain, vision, "Mir", M., 1990.

5. Shepherd G. Neurobiology, "Mir", M., 1987.

6. Shulgovskiy VV, Physiology of higher nervous activity with the basics of neurobiology, Ed. Center "Academy", M., 2008.

7. Shulgovsky V.V. Fundamentals of neurophysiology, Ed. "Aspect press", M., 2008.

8. Squire. L.R., Berg D., Bloom F.E., du Lac S., Ghosh A., Spitzer N.C. Fundamental Neuroscience, Academic Press, 3rd ed., San Diego, London, 2008.