Higher nervous activity. Higher nervous activity (HNA) is the nervous processes that underlie human behavior and ensure adaptability. Presentation "higher nervous activity" Presentation on the topic higher nervous activity of man

11.01.2024

Higher nervous activity. Reflexes Higher nervous activity. Reflexes Tasks: Tasks: To get acquainted with the role of I.M. Sechenov and I.P. Pavlov in creating the doctrine of higher nervous activity, get acquainted with the role of I.M. Sechenov and I.P. Pavlova in the creation of teaching in higher nervous activity, Let's consider the conditions for the formation of the basic mechanisms of VND - conditioned reflexes, Let's consider the conditions for the formation of the basic mechanisms of VND - conditioned reflexes, Get acquainted with Pavlov's method of studying conditioned reflexes Get acquainted with Pavlov's method of studying conditioned reflexes Establish connection and difference between conditioned and unconditioned reflexes Establish the connection and difference between conditioned and unconditioned reflexes

Updating knowledge Which organ is the higher nervous activity associated with? The brain is the seat of the mind, knowledge, skills, and experience. It seems that the smarter a living being is, the larger its brain size. Indeed, in bees, ants, and grasshoppers, it is the size of a pinhead and weighs only a few milligrams; in mice, squirrels, and sparrows, the brain is hundreds of times larger and already weighs about a gram; in cats, it is much more than in mice, and weighs approximately 30 grams, in dogs - 100 grams, in apes - 450 grams, and finally in humans - an average of 1 kilogram 400 grams! The brain weight of elephants is about 5 kilograms, and that of large fin whales is almost 7 kilograms. The brain is the seat of the mind, knowledge, skills, and experience. It seems that the smarter a living being is, the larger its brain size. Indeed, in bees, ants, and grasshoppers, it is the size of a pinhead and weighs only a few milligrams; in mice, squirrels, and sparrows, the brain is hundreds of times larger and already weighs about a gram; in cats, it is much more than in mice, and weighs approximately 30 grams, in dogs - 100 grams, in apes - 450 grams, and finally in humans - an average of 1 kilogram 400 grams! The brain weight of elephants is about 5 kilograms, and that of large fin whales is almost 7 kilograms. It turns out they are smarter. Of course not. The fact is that thinking abilities depend not only on the size of the brain, but also on the size... of the body. The greater the weight of the brain compared to the weight of the body, the better the living creature works with its head. It turns out they are smarter. Of course not. The fact is that thinking abilities depend not only on the size of the brain, but also on the size... of the body. The greater the weight of the brain compared to the weight of the body, the better the living creature works with its head. A cow's body weight is 1000 times the weight of its brain, a dog's is 500 times, and a person's is 50 times. A whale’s brain weighs 7 kilograms, but the whale pulls 21 tons, that is, it is 3 thousand times heavier than its brain. A cow's body weight is 1000 times the weight of its brain, a dog's is 500 times, and a person's is 50 times. A whale’s brain weighs 7 kilograms, but the whale pulls 21 tons, that is, it is 3 thousand times heavier than its brain. The mind depends on certain areas - the gray matter, where neurons are densely concentrated. The smarter the animal, the more gray matter it has, the more neurons in the “thinking” areas. The mind depends on certain areas - the gray matter, where neurons are densely concentrated. The smarter the animal, the more gray matter it has, the more neurons in the “thinking” areas. Man is superior to his smaller brothers in terms of weight of “thinking matter”, thanks to this man can read, write, build factories, play chess, and make scientific discoveries. Man is superior to his smaller brothers in terms of weight of “thinking matter”, thanks to this man can read, write, build factories, play chess, and make scientific discoveries.

What is a reflex? A reflex is the body’s response to irritation of receptors, carried out and controlled by the central nervous system. Assignment: What phenomena can be classified as reflexes, taking into account definition 1. the movement of plants towards the light. 2. withdrawing a hand from the fire. 3. contraction of an isolated muscle in response to irritation of the nerve approaching it with an electric current. 4. blinking of the eyes at a sharp unexpected sound. What is a reflex? A reflex is the body’s response to irritation of receptors, carried out and controlled by the central nervous system. Assignment: What phenomena can be classified as reflexes, taking into account definition 1. the movement of plants towards the light. 2. withdrawing a hand from the fire. 3. contraction of an isolated muscle in response to irritation of the nerve approaching it with an electric current. 4. blinking of the eyes at a sharp unexpected sound.

What groups of reflexes are distinguished? What groups of reflexes are distinguished? Give examples of various reflexes, explain why some are conditional, others are unconditional? Give examples of various reflexes, explain why some are conditional, others are unconditional?

We wrote down the topic of the lesson “higher nervous activity. reflexes." Explain the meaning of these words! The words “nervous activity” are clear, and “higher” The words “nervous activity” are clear, and “higher” GNI is the ability to adapt to environmental conditions. GNI is the ability to adapt to environmental conditions. Based on the definition, can we say that VND is inherent in animals? Based on the definition, can we say that VND is inherent in animals? The GNI of animals consists of a series of conditioned reflexes. The GNI of animals consists of a series of conditioned reflexes. Are the unconditioned reflexes of humans and animals different? Are the unconditioned reflexes of humans and animals different? Do food conditioned reflexes differ in animals and humans? Do food conditioned reflexes differ in animals and humans?

Unconditioned and conditioned reflexes to natural stimuli are the same in higher animals and humans. This is explained by the origin of man from animal ancestors. But man differs from animals in the complexity of his behavior, which is explained by the presence in man of consciousness, thinking, and speech (speech reflexes). A person has speech centers in the cerebral cortex. What reflexes does a newborn baby have? What reflexes does a newborn child have? (unconditioned) Which reflex appears first? (respiratory) An infant acquires reflexes gradually. How does an infant react to words? (no way) By the age of 1.5-2 years, the child’s cerebral cortex is finally formed, and speech centers begin to function. Words lead to abstract (generalized) thinking. Experience: Raise your hands after you hear a knock. Conclusion - the human brain can react to words, as well as to the objects or actions that they represent. Animals also react to the word (circus) - but they react to the sound, and humans to the meaning.

Assignment: read the words, share your associations when these words are mentioned: Apple, Apple, dream, dream, one, one, word, word, table, table, board, board, child, child, student. student. Conclusion: a person has abstract (abstract, associative) thinking; he uses words to express the general properties of objects. Conclusion: a person has abstract (abstract, associative) thinking; he uses words to express the general properties of objects.

I.M. Sechenov was the first to propose that reflexes are the basis of human GND, discovered and proved the phenomenon of inhibition of the central nervous system. That inhibition is the physiological basis of will. I.M. Sechenov was the first to propose that reflexes are the basis of human GND, discovered and proved the phenomenon of inhibition of the central nervous system. That inhibition is the physiological basis of will. Work on the study of VND processes was continued by I.P. Pavlov. It was he who discovered the main cortex of the cerebral hemispheres - the formation and inhibition of conditioned reflexes. Work on the study of VND processes was continued by I.P. Pavlov. It was he who discovered the main cortex of the cerebral hemispheres - the formation and inhibition of conditioned reflexes. Test dogs in Pavlov's laboratory salivated at the sight of food. Some employees said that the dog understands, remembers, knows that it will be given food. Test dogs in Pavlov's laboratory salivated at the sight of food. Some employees said that the dog understands, remembers, knows that it will be given food. But Pavlov set out to explain the physiological basis of salivation. But Pavlov set out to explain the physiological basis of salivation. Having proved through a whole series of precise experiments that the jaw is secreted in response to irritation of the sensory organs, signaling to the cortex about the upcoming arrival of food, the scientist came to the conclusion that the study of reflexes can be used as the basis for the activity of the cortex. Having proved through a whole series of precise experiments that the jaw is secreted in response to irritation of the sensory organs, signaling to the cortex about the upcoming arrival of food, the scientist came to the conclusion that the study of reflexes can be used as the basis for the activity of the cortex. We opened the textbook, using the drawings we will explain Pavlov’s experiments. We opened the textbook, using the drawings we will explain Pavlov’s experiments.

What is a conditioned reflex? What is a conditioned reflex? Conditioned reflex (secretion of saliva in a dog) = Conditioned reflex (secretion of saliva in a dog) = conditioned stimulus (lamp light) + unconditioned conditioned stimulus (lamp light) + unconditioned stimulus stimulus (food) (food) If food is not given after the salivary reflex has been developed , then saliva will not be released (inhibition will occur in the cerebral cortex). The reflex fades away. When developing conditioned reflexes in the cortex, b.p. a temporary connection arises - the main mechanism of activity of the bp cortex, allowing the cortex to adapt the body to changing conditions REMEMBER THE DEFINITION OF VND!

Compiled by Nemirovich N.N. Biology teacher MBOU "Secondary School No. 6" Sergiev Posad

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First and second signaling system
Formation of a dynamic stereotype
Consciousness as a specific property of a person.
Features of unconscious subconscious processes.

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Target

Using knowledge about the social factors of human evolution, explain the reasons for the emergence of consciousness as an exclusive property of man.

Develop knowledge about higher nervous activity based on consideration of the characteristics of human GNI.
Develop the ability to compare.

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Consciousness is the result of the action of social factors in human evolution.
Consciousness is the highest level of mental development, characteristic only of humans

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Social factors of anthropogenesis

Collective labor activity
Communication - Speech
Consciousness

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First signaling system

Sensation - impact on the receptor
Perception is the basis of ideas
Image

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"Reflexes of the Brain" 1863

Mental (“spiritual”) human activity is explained by the reflex principle of the nervous system.

Sechenov I. M. 1829-1905

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Principles of reflex theory

Principle of Causality: Nervous phenomena do not occur without a cause.
The principle of structure: the functions occurring in the brain correspond to its material carrier - an element of the nervous system
The principle of unity of analysis and synthesis: the work of the brain is built on the basis of analysis and synthesis. The body extracts useful information, processes it and forms response actions.

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Sechenov stated:

That brain reflexes include three parts:

Excitement in the senses
Processes of excitation and inhibition in the brain
Human movements and actions, i.e. behavior

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Pavlov I.P. is the founder of the physiology of behavior.

Pavlov I. P. 1849-1936

Opened the second alarm system
Behavior is a combination of conditioned and unconditioned reflexes
Created the doctrine of unconditioned and conditioned reflexes

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Formation of conditioned reflexes.

Reaction to external influence (noise) – unconditioned reflex – conditioned reflex (indicative).
A conditioned reflex is a temporary connection for the duration of the conditions.
The conditioned reflex forms the basis of teaching and education.

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Imprint

The link between congenital and acquired forms of behavior

Meaning:

Remembering parents;
Adopt behavioral skills;
Formation of a person’s personality;

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Second alarm system:

Words are second signals – signals of signals.
Words are formed in the process of communication
Word – thinking – cognition.

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Dynamic stereotype

Combining several conditioned reflexes into a dynamic chain.
The basis of reading and writing, habits, acquiring the skills of walking, swimming, running.
The basis of human behavior
Prevents overcoming bad habits.

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Consciousness is the highest level of mental development.

Conscious activity:

Makes a plan.
Considers ways to implement the plan.
Relies on the experience of other people (or takes advice).
Achieves the set goal.

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Processes of consciousness

In humans
Memory.
Imagination
Thinking
In animals
Rational activity
Concrete thinking

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The term “higher nervous activity” was first introduced into science by I. P. Pavlov, who considered it equivalent to the concept of mental activity. Pavlov considered all forms of mental activity, including human thinking and consciousness, to be elements of higher nervous activity. Ivan Petrovich Pavlov (1849-1936)

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The difference between the GNI of humans and the GNI of animals In humans, in the process of social and labor activity, a fundamentally new signaling system arises and reaches a high level of development. The signaling system is a system of conditioned and unconditional reflex connections between the higher nervous system of animals (including humans) and the surrounding world. There are first and second signaling systems.

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The first signaling system is the conditioned reflex activity of the cerebral cortex, associated with the perception through receptors of immediate specific stimuli (signals) of the external world (light, color, sound, temperature...).

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I. P. Pavlov wrote: “This is the first signal system of reality, common to us with animals.”

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second signaling system (signal signal). conditioned reflex activity of the cerebral cortex associated with the perception of signals of any property (speech, gestures), and each of these signals has a correspondence in the first signal system and is capable of closing the reflex. According to I.P. Pavlov, an extraordinary addition to the mechanisms of nervous activity is the II signaling system, which arose as a result of human labor activity and the appearance of speech.

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The activity of the II signaling system is manifested in speech conditioned reflexes. A word that is audible, pronounced (speech), visible (writing, the alphabet of the deaf and dumb), tangible (the alphabet of the blind) is a conditioned stimulus, a signal about specific environmental stimuli, i.e., a “signal of signals.”

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“The word,” writes I.P. Pavlov, “made up our second, special signal system of reality, being a signal of the first signals.”

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The frontal lobes and brain speech centers participate in the formation of reflexes of the II signal system.

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Associated with the 2nd signaling system is a special human characteristic of VND - the ability to abstract and generalize signals coming through the 1st signaling system. The signal meaning of a word is associated not with a simple sound combination, but with its semantic content. The II signaling system provides abstract thinking in the form of conclusions, concepts, and judgments.

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Features of the II signaling system. 1) Available only in humans. 2) Formation of conditioned reflexes on the basis of the first signal system based on speech activity. 3) Provides the perception of information in the form of symbols (words, signs, formulas, gestures). 4) The frontal lobes are involved in the formation of speech reflexes. 5) Provides abstract thinking for a person.

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In all people, the second signaling system prevails over the first. The degree of this predominance varies. This gives grounds to divide human higher nervous activity into three types: mental, artistic, average (mixed).

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The thinking type includes persons with a significant predominance of the second signaling system over the first. They have more developed abstract thinking (mathematicians, philosophers); Their direct reflection of reality occurs in insufficiently vivid images.

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Description of the presentation Presentation of physiology of GNI and SS children on slides

Age-related features of the development of the central nervous system, physiology of higher nervous activity and sensory systems. Part

Higher nervous activity is the activity of the higher parts of the central nervous system, ensuring the most perfect adaptation of animals and humans to the environment. Higher nervous activity includes gnosis (cognition), praxis (action), speech, memory and thinking, consciousness, etc. The behavior of the body is the crowning achievement of higher nervous activity. Mental activity is an ideal, subjectively conscious activity of the body, carried out with the help of neurophysiological processes. Psyche is the property of the brain to carry out mental activity. Consciousness is an ideal, subjective reflection of reality with the help of the brain.

History of science For the first time, the idea of the reflex nature of the activity of the higher parts of the brain was broadly and in detail formulated by the founder of Russian physiology I.M. Sechenov and presented in the work “Reflexes of the Brain”. The ideas of I.M. Sechenov were further developed in the works of another outstanding Russian physiologist, I.P. Pavlov, who discovered the ways of objective experimental study of the functions of the cerebral cortex, as well as developed the method of conditioned reflexes and created a holistic doctrine of higher nervous activity. The first generalizations concerning the essence of the psyche can be found in the works of ancient Greek and Roman scientists (Thales, Anaximenes, Heraclitus, Democritus, Plato, Aristotle, Epicurus, Lucretius, Galen). René Descartes' (1596-1650) substantiation of the reflex mechanism of the relationship between the organism and the environment was of exceptional importance for the development of materialistic views in the study of the physiological foundations of mental activity. On the basis of the reflex mechanism, Descartes tried to explain the behavior of animals and simply automatic human actions.

An unconditioned reflex is a relatively constant, species-specific, stereotypical, genetically fixed reaction of the body to internal or external stimuli, carried out through the central nervous system. Hereditarily fixed unconditioned reflexes can arise, be inhibited and modified in response to a wide variety of stimuli that an individual encounters. A conditioned reflex is a reaction of the organism developed in ontogenesis to a stimulus that was previously indifferent to this reaction. A conditioned reflex is formed on the basis of an unconditioned (innate) reflex.

I.P. Pavlov at one time divided unconditioned reflexes into three groups: simple, complex and complex unconditioned reflexes. Among the most complex unconditioned reflexes, he identified the following: 1) individual - food, active and passive defensive, aggressive, freedom reflex, exploratory, play reflex; 2) species - sexual and parental. According to Pavlov, the first of these reflexes ensure the individual self-preservation of the individual, the second - the preservation of the species.

Vital ● Nutritional ● Drinking ● Defensive ● Regulation of sleep - wakefulness ● Saving energy Role-playing (zoosocial) ● Sexual ● Parental ● Emotional ● Resonance, “empathy” ● Territorial ● Hierarchical Self-development ● Research ● Imitation ● Gaming ● Overcoming resistance, freedom. The most important unconditioned reflexes of animals (according to P.V. Simonov, 1986, amended) Note: due to the peculiarities of the terminology of that time, instincts are called unconditioned reflexes (these concepts are close, but not identical).

Features of the organization of an unconditioned reflex (instinct) Instinct is a complex of motor acts or a sequence of actions characteristic of an organism of a given species, the implementation of which depends on the functional state of the animal (determined by the dominant need) and the current situation. The external stimuli that make up the triggering situation are called “key stimuli.” The concept of “drive and drive reflex” according to Yu. Konorsky Drive reflexes are a state of motivational arousal that occurs when the “corresponding drive center” is activated (for example, hunger arousal). Drive is hunger, thirst, rage, fear, etc. According to the terminology of Yu. Konorsky, drive has an antipode - “antidrive”, i.e. a state of the body that occurs after satisfying a certain need, after fulfilling the drive reflex.

Many human actions are based on sets of standard behavior programs that we inherited from our ancestors. They are influenced by the characteristics of physiological processes, which can occur differently depending on the age or gender of a person. Knowledge of these factors greatly facilitates the understanding of the behavior of other people, and allows the teacher to more effectively organize the learning process. Features of human biology allow him to use standard behavioral programs that contribute to survival in conditions from the far north to tropical forests and from sparsely populated deserts to giant cities

How many instinctive programs do children have? Children have hundreds of instinctive programs that ensure their survival in the early stages of life. True, some of them have lost their former meaning. But some programs are vital. Thus, a complex program working on the principle of imprinting is responsible for the child’s mastery of language.

Why are children's pockets full of stuff? In childhood, people behave like typical gatherers. The child is still crawling, but he already notices everything, picks it up and puts it in his mouth. As he gets older, he spends a significant part of his time collecting all sorts of things in a variety of places. Their pockets are filled with the most unexpected objects - nuts, seeds, shells, pebbles, strings, often mixed with beetles, corks, wires! All this is a manifestation of the same ancient instinctive programs that made us human. In adults, these programs often manifest themselves in the form of a craving for collecting a wide variety of objects.

Structure of nervous tissue Nervous tissue: The neuron is the main structural and functional unit of nervous tissue. Its functions are related to the perception, processing, transmission and storage of information. Neurons consist of a body and processes - a long one, along which excitation goes from the cell body - an axon and dendrites, along which excitation goes to the cell body.

The nerve impulses that a neuron generates propagate along the axon and are transmitted to another neuron or to an executive organ (muscle, gland). The complex of formations that serve for such transmission is called a synapse. The neuron that transmits the nerve impulse is called presynaptic, and the neuron that receives it is called postsynaptic.

The synapse consists of three parts - the presynaptic terminal, the postsynaptic membrane and the synaptic cleft located between them. Presynaptic endings are most often formed by an axon, which branches, forming specialized extensions at its end (presynapse, synaptic plaques, synaptic buttons, etc.). Synapse structure: 1 - presynaptic ending; 2 - postsynaptic membrane; 3 - synoptic gap; 4 - vesicle; 5 - endoplasmic reticulum; 6 - mitochondria. Internal structure of a neuron A neuron has all the organelles characteristic of a normal cell (endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes, ribosomes, etc.). One of the main structural differences between neurons and other cells is associated with the presence in their cytoplasm of specific formations in the form of lumps and grains of various shapes - Nissl substance (tigroid). The Golgi complex is also well developed in nerve cells; there is a network of fibrillar structures - microtubules and neurofilaments.

Neuroglia, or simply glia, is a collection of auxiliary cells of nervous tissue. Makes up about 40% of the volume of the central nervous system. The number of glial cells is on average 10-50 times greater than neurons. Types of neuroglial cells: ] - ependymocytes; 2 - protoplasmic astrocytes; 3 - fibrous astrocytes; 4 - oligodendrocytes; 5 - microglia Ependymocytes form a single layer of ependymal cells, actively regulate the exchange of substances between the brain and blood, on the one hand, and the cerebrospinal fluid and blood, on the other. Astrocytes are located in all parts of the nervous system. These are the largest and most numerous of the glial cells. Astrocytes actively participate in the metabolism of the nervous system. Oligodendrocytes, much smaller than astrocytes, perform a trophic function. Analogues of oligodendrocytes are Schwann cells, which also form sheaths (both myelinated and non-myelinated) around fibers. Microglia. Microgliocytes are the smallest of the glial cells. Their main function is protective.

The structure of nerve fibers A is myelin; B - unmyelinated; I - fiber; 2 - myelin layer; 3 - Schwann cell nucleus; 4 - microtubules; 5 - Neurofilaments; 6 - mitochondria; 7 - connective tissue membrane Fibers are divided into myelinated (pulp) and non-myelinated (pulpless). Unmyelinated nerve fibers are covered only by a sheath formed by the body of the Schwann (neuroglial) cell. The myelin sheath is a double layer of cell membrane and its chemical composition is a lipoprotein, i.e. a combination of lipids (fat-like substances) and proteins. The myelin sheath effectively insulates the nerve fiber electrically. It consists of cylinders 1.5-2 mm long, each of which is formed by its own glial cell. The cylinders separate the nodes of Ranvier - sections of the fiber not covered with myelin (their length is 0.5 - 2.5 microns), which play a large role in the rapid conduction of nerve impulses. On top of the myelin sheath, the pulp fibers also have an outer sheath - the neurilemma, formed by the cytoplasm and nucleus of neuroglial cells.

Functionally, neurons are divided into sensitive (afferent) nerve cells that perceive stimuli from the external or internal environment of the body. , motor (efferent) control contractions of striated muscle fibers. They form neuromuscular synapses. Executive neurons control the work of internal organs, including smooth muscle fibers, glandular cells, etc., between them there may be intercalary neurons (associative) connections between sensory and executive neurons. The functioning of the nervous system is based on reflexes. A reflex is the body’s response to stimulation, which is carried out and controlled by the nervous system.

A reflex arc is the path along which excitation passes during a reflex. It consists of five sections: receptor; sensory neuron transmitting impulses to the central nervous system; nerve center; motor neuron; a working organ that reacts to the received irritation.

The formation of the nervous system occurs in the 1st week of intrauterine development. The greatest intensity of division of nerve cells in the brain occurs in the period from the 10th to the 18th week of intrauterine development, which can be considered a critical period for the formation of the central nervous system. If the number of nerve cells in an adult is taken as 100%, by the time the child is born, only 25% of the cells are formed, by 6 months - 66%, and by one year - 90-95%.

A receptor is a sensitive formation that transforms the energy of a stimulus into a nervous process (electrical excitation). The receptor is followed by a sensory neuron located in the peripheral nervous system. The peripheral processes (dendrites) of such neurons form a sensory nerve and go to the receptors, and the central ones (axons) enter the central nervous system and form synapses on its interneurons. A nerve center is a group of neurons necessary to carry out a specific reflex or more complex forms of behavior. It processes information that comes to it from the senses or from other nerve centers and in turn sends commands to executive neurons or other nerve centers. It is thanks to the reflex principle that the nervous system ensures self-regulation processes.

Scientists who made a great contribution to the development of the conditioned reflex theory of I. P. Pavlov: L. A. Orbeli, P. S. Kupalov, P. K. Anokhin, E. A. Asratyan L. G. Voronin, Yu. Konorsky and many others . Rules for developing a classical conditioned reflex When combining, an indifferent stimulus (for example, the sound of a bell) must be followed by a significant stimulus (for example, food). After several combinations, the indifferent stimulus becomes a conditioned stimulus—that is, a signal that predicts the appearance of a biologically significant stimulus. The significance of the stimulus can be associated with any motivation (hunger, thirst, self-preservation, care for offspring, curiosity, etc.)

Examples of some classical conditioned reflexes used in laboratory conditions on animals and humans at the present time: - Salivary reflex (combination of any stimulus with food) - manifests itself in the form of salivation in response to the stimulus. - Various defensive reactions and fear reactions (a combination of any US with electrical pain reinforcement, a sharp loud sound, etc.) - manifests itself in the form of various muscle reactions, changes in heart rate, galvanic skin response, etc. - Blinking reflexes (a combination of any US with an impact on the eye area with a stream of air or a click on the bridge of the nose) - manifested in blinking of the eyelid - Food aversion reaction (a combination of food as an US with artificial effects on the body that cause nausea and vomiting) - manifested in refusal of the corresponding type of food despite hunger. - and etc.

Types of conditioned reflexes Natural are called conditioned reflexes that are formed in response to stimuli that are natural, necessarily accompanying signs, properties of the unconditioned stimulus on the basis of which they are developed (for example, the smell of food during its preparation). Artificial are called conditioned reflexes that are formed in response to stimuli that, as a rule, are not directly related to the unconditional stimulus that reinforces them (for example, a light stimulus reinforced by food).

According to the efferent link of the reflex arc, in particular according to the effector on which reflexes appear: vegetative and motor, instrumental. Autonomic conditioned reflexes include the classic salivary conditioned reflex, as well as a number of motor-vegetative reflexes - vascular, respiratory, food, pupillary, cardiac and etc. Instrumental conditioned reflexes can be formed on the basis of unconditioned reflex motor reactions. For example, motor defensive conditioned reflexes in dogs are developed very quickly, first in the form of a general motor reaction, which then quickly specializes. Conditioned reflexes for time are special reflexes that are formed with regular repetition of an unconditioned stimulus. For example, feeding the baby every 30 minutes.

Dynamics of the main nervous processes according to Pavlov The spread of the nervous process from the central focus to the surrounding zone is called irradiation of excitation. The opposite process - limitation, reduction of the zone of the source of excitation is called concentration of excitation. The processes of irradiation and concentration of nervous processes form the basis of inductive relationships in the central nervous system. Induction is the property of the main nervous process (excitation or inhibition) to cause the opposite effect around itself and after itself. Positive induction is observed when the focus of the inhibitory process, immediately or after the cessation of the inhibitory stimulus, creates an area of increased excitability in the surrounding area. Negative induction occurs when the focus of excitation creates a state of reduced excitability around itself and after itself. Scheme of experiment for studying the movement of nervous processes: + 1 - positive stimulus (carcass); -2 - -5 - negative stimuli (carcass)

Types of inhibition according to I.P. Pavlov: 1. External (unconditional) inhibition. — permanent brake — fading brake 2. Excessive (protective) braking. 3. Internal (conditioned) inhibition. — extinction inhibition (extinction) — differential inhibition (differentiation) — conditioned inhibition — delay inhibition

Dynamics of conditioned reflex activity External (unconditioned) inhibition is the process of emergency weakening or cessation of individual behavioral reactions under the influence of stimuli coming from the external or internal environment. The cause may be various conditioned reflex reactions, as well as various unconditioned reflexes (for example, an orienting reflex, a defensive reaction - fear, fear). Another type of innate inhibitory process is the so-called transcendental inhibition. It develops with prolonged nervous stimulation of the body. Conditioned (internal) inhibition is acquired and manifests itself in the form of delay, extinction, and elimination of conditioned reactions. Conditioned inhibition is an active process in the nervous system, developing, like conditioned excitation, as a result of development.

Extinction inhibition develops in the absence of reinforcement of the conditioned signal by the unconditioned one. Extinction inhibition is often called extinction. A conditioned inhibitor is formed when a combination of a positive conditioned stimulus and an indifferent one is not reinforced. When inhibiting delay, reinforcement is not canceled (as in the types of inhibition discussed above), but is significantly delayed from the beginning of the action of the conditioned stimulus.

In response to repeated or monotonous stimuli, internal inhibition certainly develops. If such stimulation continues, sleep occurs. The transition period between wakefulness and sleep is called the hypnotic state. I.P. Pavlov divided the hypnotic state into three phases depending on the size of the area of the cerebral cortex covered by inhibition and the corresponding reactivity of various brain centers in the process of implementing conditioned reflexes. The first of these phases is called equalization. At this time, strong and weak stimuli evoke the same conditioned responses. The paradoxical phase is characterized by deeper sleep. In this phase, weak stimuli evoke a more intense response than strong ones. The ultraparadoxical phase means even deeper sleep, when only weak stimuli cause a response, and strong ones lead to an even greater spread of inhibition. These three phases are followed by deep sleep.

Anxiety is a property determined by the degree of anxiety, concern, and emotional tension of a person in a responsible and especially threatening situation. Emotional excitability is the ease of occurrence of emotional reactions to external and internal influences. Impulsivity characterizes the speed of reaction, decision making and execution. Regidity and lability determine the ease and flexibility of a person’s adaptation to changing external influences: someone who has difficulty adapting to a changed situation, who is inert in behavior, does not change their habits and beliefs is regiscent; labile is someone who quickly adapts to a new situation.

CENTRAL NERVOUS SYSTEM The central nervous system includes those parts of the nervous system whose neuron bodies are protected by the spine and skull - the spinal cord and brain. In addition, the brain and spinal cord are protected by membranes (dura, arachnoid and soft) made of connective tissue. The brain is anatomically divided into five sections: ♦ medulla oblongata; ♦ hindbrain, formed by the pons and cerebellum; ♦ midbrain; ♦ diencephalon, formed by the thalamus, epithalamus, hypothalamus; ♦ telencephalon, consisting of cerebral hemispheres covered with cortex. Below the cortex are the basal ganglia. The medulla oblongata, pons and midbrain are brain stem structures.

The brain is located in the cerebral part of the skull, which protects it from mechanical damage. On the outside, it is covered with meninges with numerous blood vessels. The weight of the brain in an adult reaches 1100 - 1600 g. The brain can be divided into three sections: posterior, middle and anterior. The posterior section includes the medulla oblongata, pons and cerebellum, and the anterior section includes the diencephalon and cerebral hemispheres. All sections, including the cerebral hemispheres, form the brain stem. Inside the cerebral hemispheres and in the brain stem there are cavities filled with fluid. The brain consists of white matter in the form of conductors that connect parts of the brain to each other, and gray matter located inside the brain in the form of nuclei and covering the surface of the hemispheres and cerebellum in the form of the cortex.

The longitudinal fissure of the cerebrum divides the cerebrum into two hemispheres - right and left. The cerebral hemispheres are separated from the cerebellum by a transverse fissure. In the cerebral hemispheres, three phylogenetically and functionally different systems are combined: 1) olfactory brain, 2) basal ganglia, 3) cerebral cortex (cloak).

The cerebral cortex is a multilayer neural tissue with many folds with a total area in both hemispheres of approximately 2200 cm2, its volume corresponds to 40% of the brain mass, its thickness ranges from 1.3 to 4.5 mm, and the total volume is 600 cm3 The cerebral cortex includes 10 9 – 10 10 neurons and many glial cells. The cortex has 6 layers (I–VI), each of which consists of pyramidal and stellate cells. In layers I–IV, the perception and processing of signals entering the cortex in the form of nerve impulses occurs. The efferent pathways leaving the cortex are formed mainly in layers V–VI. Structural and functional characteristics of the cerebral cortex

The occipital lobe receives sensory input from the eyes and recognizes shape, color and movement. The frontal lobe controls muscles throughout the body. The motor association region of the frontal lobe is responsible for acquired motor activity. The anterior center of the visual field controls voluntary scanning of the eyes. Broca's center transfers thoughts to external and then internal speech. The temporal lobe recognizes the basic characteristics of sound, its pitch and rhythm. The area of auditory associations (“Wernicke’s center” - temporal lobes) understands speech. The vestibular area in the temporal lobe receives signals from the semicircular canals of the ear and interprets the feelings of gravity, balance and vibration. The olfactory center is responsible for the sensations caused by smell. All of these areas are directly connected to memory centers in the limbic system. The parietal lobe recognizes touch, pressure, pain, heat, cold without visual sensations. It also contains the taste center, responsible for the sensation of sweet, sour, bitter and salty.

Localization of functions in the cerebral cortex Sensory areas of the cortex The central sulcus separates the frontal lobe from the parietal lobe, the lateral sulcus separates the temporal lobe, the parieto-occipital sulcus separates the occipital lobe from the parietal lobe. The cortex is divided into sensory, motor and association zones. Sensitive zones are responsible for analyzing information coming from the senses: occipital - for vision, temporal - for hearing, smell and taste, parietal - for skin and joint-muscular sensitivity.

Moreover, each hemisphere receives impulses from the opposite side of the body. Motor zones are located in the posterior regions of the frontal lobes, from here commands for contraction of skeletal muscles come. Association zones are located in the frontal lobes of the brain and are responsible for developing programs for behavior and control of human activities; their mass in humans is more than 50% of the total mass of the brain.

The medulla oblongata is a continuation of the spinal cord and performs reflex and conduction functions. Reflex functions are associated with the regulation of the respiratory, digestive and circulatory systems; here are the centers of protective reflexes - coughing, sneezing, vomiting.

The bridge connects the cerebral cortex with the spinal cord and cerebellum and primarily performs a conductive function. The cerebellum is formed by two hemispheres, the outside is covered with a cortex of gray matter, under which there is white matter. The white matter contains nuclei. The middle part - the worm - connects the hemispheres. Responsible for coordination, balance and affects muscle tone.

The diencephalon is divided into three parts: the thalamus, the epithalamus (epithalamus, which includes the pineal gland), and the hypothalamus. The thalamus contains subcortical centers of all types of sensitivity, and excitement from the senses comes here. The hypothalamus contains the highest centers of regulation of the autonomic nervous system; it controls the constancy of the internal environment of the body.

Structure and functions of the brain Here are the centers of appetite, thirst, sleep, thermoregulation, i.e. regulation of all types of metabolism is carried out. Neurons of the hypothalamus produce neurohormones that regulate the functioning of the endocrine system. The diencephalon also contains emotional centers: centers of pleasure, fear, and aggression. Part of the brain stem.

Structure and functions of the brain The forebrain consists of the cerebral hemispheres, connected by the corpus callosum. The surface is formed by the bark, the area of which is about 2200 cm2. Numerous folds, convolutions and grooves significantly increase the surface of the bark. The human cortex contains from 14 to 17 billion nerve cells, arranged in 6 layers, the thickness of the cortex is 2 - 4 mm. Clusters of neurons in the depths of the hemispheres form the subcortical nuclei.

A person is characterized by functional asymmetry of the hemispheres, the left hemisphere is responsible for abstract logical thinking, speech centers are also located there (Broca's center is responsible for pronunciation, Wernicke's center for understanding speech), the right hemisphere is for imaginative thinking, musical and artistic creativity.

The most important parts of the brain that form the limbic system are located along the edges of the cerebral hemispheres, as if “edging” them. The most important structures of the limbic system: 1. Hypothalamus 2. Amygdala 3. Orbitofrontal cortex 4. Hippocampus 5. Mamillary bodies 6. Olfactory bulbs and olfactory tubercle 7. Septum 8. Thalamus (anterior group of nuclei) 9. Cingulate gyrus (etc. .)

Diagram of the location of the limbic system and thalamus. 1 - cingulate gyrus; 2- frontotemporal and subcallosal cortex; 3 - orbital cortex; 4 - primary olfactory cortex; 5 - amygdala complex; 6 — hippocampus (not shaded) and hippocampal gyrus; 7 - thalamus and mammillary bodies (according to D. Plug) Limbic system

The thalamus functions as a "switching station" for all sensations entering the brain, except olfactory ones. It also transmits motor impulses from the cerebral cortex along the spinal cord to the muscles. In addition, the thalamus recognizes sensations of pain, temperature, light touch and pressure, and is also involved in emotional processes and memory.

Nonspecific nuclei of the thalamus are represented by the median center, paracentral nucleus, central medial and lateral, submedial, ventral anterior, parafascicular complexes, reticular nucleus, periventricular and central gray mass. The neurons of these nuclei form their connections according to the reticular type. Their axons rise into the cerebral cortex and contact all its layers, forming not local, but diffuse connections. Nonspecific nuclei receive connections from the RF of the brainstem, hypothalamus, limbic system, basal ganglia, and specific nuclei of the thalamus.

The hypothalamus controls the functioning of the pituitary gland, normal body temperature, food intake, sleep and wakefulness. It is also the center responsible for behavior in extreme situations, manifestations of rage, aggression, pain and pleasure.

The amygdala ensures the perception of objects as having one or another motivational-emotional meaning (scary/dangerous, edible, etc.), and it provides both innate reactions (for example, an innate fear of snakes) and those acquired through the individual’s own experience.

The amygdala is connected to areas of the brain responsible for processing cognitive and sensory information, as well as areas related to combinations of emotions. The amygdala coordinates fear or anxiety responses triggered by internal cues.

The hippocampus uses sensory information from the thalamus and emotional information from the hypothalamus to form short-term memory. Short-term memory, activating the neural networks of the hippocampus, can then move into “long-term storage” and become long-term memory for the entire brain. The hippocampus is a central part of the limbic system.

Temporal cortex. Participates in the imprinting and storage of figurative information. Hippocampus It acts as the first point of convergence of conditioned and unconditional stimuli. The hippocampus is involved in fixing and retrieving information from memory. Reticular formation. It has an activating effect on the structures involved in fixing and reproducing memory traces (engrams), and is also directly involved in the processes of engram formation. Thalamocortical system. Promotes the organization of short-term memory.

The basal ganglia control nerve impulses between the cerebellum and the anterior lobe of the brain and thereby help control body movements. They promote fine motor control of the facial muscles and eyes, which reflect emotional states. The basal ganglia are connected to the anterior lobe of the brain through the substantia nigra. They coordinate the mental processes involved in planning the order and coherence of upcoming actions over time.

The orbitofrontal cortex (located on the lowest anterior side of the frontal lobe) appears to mediate self-control of emotions and the complex manifestations of motivation and emotion in the psyche.

NERVOUS CIRCUIT OF DEPRESSION: LORD OF THE MOOD Patients with depression are characterized by general lethargy, depressed mood, slow reactions and memory impairment. It appears that brain activity is significantly reduced. At the same time, symptoms such as anxiety and sleep disturbances suggest that some parts of the brain, on the contrary, are hyperactive. Using visualization of the brain structures most affected by depression, it was discovered that the reason for this mismatch in their activity lies in the dysfunction of a tiny area - area 25. This field is directly connected to such areas as the amygdala, which is responsible for the development of fear and anxiety, and the hypothalamus , triggering stress reactions. In turn, these departments exchange information with the hippocampus (the center of memory formation) and the insular lobe (involved in the formation of perceptions and emotions). In individuals with genetic characteristics associated with reduced serotonin transport, the size of field 25 is reduced, which may be accompanied by an increased risk of depression. Thus, area 25 may be a kind of “master controller” of the depression neural circuit.

The processing of all emotional and cognitive information in the limbic system is of a biochemical nature: certain neurotransmitters are released (from the Latin transmuto - transmit; biological substances that determine the conduction of nerve impulses). If cognitive processes occur against the background of positive emotions, then neurotransmitters such as gamma-aminobutyric acid, acetylcholine, interferon and intergluekins are produced. They activate thinking and make memorization more effective. If learning processes are built on negative emotions, then adrenaline and cortisol are released, which reduce the ability to learn and remember.

Timing Development of the central nervous system in the prenatal period of ontogenesis Embryonic stage 2-3 weeks Formation of the neural plate 3-4 weeks Closing of the neural tube 4 weeks Formation of three brain vesicles 5 weeks Formation of five brain vesicles 7 weeks Growth of the cerebral hemispheres, beginning of proliferation of neuroblasts 2 months. Growth of the cerebral cortex with a smooth surface Fetal stages 2, 5 months. Thickening of the cerebral cortex 3 months. Beginning of corpus callosum formation and glial growth 4 months. Growth of lobules and grooves in the cerebellum 5 months. Formation of the corpus callosum, growth of primary grooves and histological layers 6 months Differentiation of cortical layers, myelination. formation of synaptic connections, formation of interhemispheric asymmetry and gender differences 7 months. The appearance of six cell layers, grooves, convolutions, asymmetry of the hemispheres 8-9 months. Rapid development of secondary and tertiary sulci and gyri, development of asymmetry in the structure of the brain, especially in the temporal lobes

The first stage (from the prenatal period to 2-3 years) The basis is laid (the first functional block of the brain) for the interhemispheric support of neurophysiological, neurohumoral, sensory-vegetative and neurochemical asymmetries. The first functional block of the brain provides regulation of tone and wakefulness. The brain structures of the first block are located in the stem and subcortical formations, which simultaneously tone the cortex and experience its regulatory influence. The main brain formation that provides tone is the reticular (reticular) formation. The ascending and descending fibers of the reticular formation are a self-regulating formation of the brain. At this stage, the deep neurobiological prerequisites for the formation of the future style of mental and educational activity of the child manifest themselves for the first time.

Even in utero, the child himself determines the course of his development. If the brain, by its level of development, is not ready for the moment of childbirth, then birth trauma is possible. The birth process largely depends on the activity of the child’s body. He must overcome the pressure of the mother's birth canal, make a certain number of turns and pushing movements, adapt to the effects of gravity, etc. The success of birth depends on the sufficiency of the cerebral systems of the brain. For these reasons, there is a high probability of dysontogenetic development of children born by cesarean section, premature or post-term.

By the birth of a child, the brain is large relative to body weight and is: in a newborn - 1/8-1/9 per 1 kg of body weight, in a 1-year-old child - 1/11-1/12, in a 5-year-old child - 1/13- 1/14, in an adult – 1/40. The pace of development of the nervous system occurs faster, the smaller the child. It occurs especially vigorously during the first 3 months of life. Differentiation of nerve cells is achieved by the age of 3, and by the age of 8 the cerebral cortex is similar in structure to the cerebral cortex of an adult.

The blood supply to the brain is better in children than in adults. This is explained by the richness of the capillary network, which continues to develop after birth. The abundant blood supply to the brain ensures that rapidly growing nervous tissue needs oxygen. And its need for oxygen is more than 20 times higher than that of muscles. The outflow of blood from the brain in children of the first year of life differs from that in adults. This creates conditions conducive to greater accumulation of toxic substances and metabolites in various diseases, which explains the more frequent occurrence of toxic forms of infectious diseases in young children. At the same time, the brain substance is very sensitive to increased intracranial pressure. An increase in cerebrospinal fluid pressure causes a rapid increase in degenerative changes in nerve cells, and the longer existence of hypertension causes their atrophy and death. This is confirmed in children who suffer from intrauterine hydrocephalus.

The dura mater in newborns is relatively thin, fused with the bones of the base of the skull over a large area. The venous sinuses are thin-walled and relatively narrower than in adults. The pia and arachnoid membranes of the brain of newborns are extremely thin, the subdural and subarachnoid spaces are reduced. The cisterns located at the base of the brain, on the contrary, are relatively large. The cerebral aqueduct (aqueduct of Sylvius) is wider than in adults. As the nervous system develops, the chemical composition of the brain changes significantly. The amount of water decreases, the content of proteins, nucleic acids, and lipoproteins increases. Ventricles of the brain. 1 - left lateral ventricle with frontal, occipital and temporal horns; 2 - interventricular foramen; 3 - third ventricle; 4 - Sylvian aqueduct; 5 - fourth ventricle, lateral recess

Second stage (from 3 to 7-8 years). It is characterized by activation of the interhippocampal commissural (commissures are nerve fibers that interact between the hemispheres) systems. This area of the brain provides interhemispheric organization of memory processes. During this period of ontogenesis, interhemispheric asymmetries are fixed, the predominant function of the hemispheres in speech, individual lateral profile (combination of the dominant hemisphere and the leading arm, leg, eye, ear), and functional activity is formed. Disruption of the formation of this level of the brain can lead to pseudo-left-handedness.

The second functional block receives, processes and stores information. It is located in the outer parts of the new cortex of the brain and occupies its posterior parts, including the visual (occipital), auditory (temporal) and general sensory (parietal) zones of the cortex. These areas of the brain receive visual, auditory, vestibular (general sensory) and kinesthetic information. This also includes the central zones of taste and olfactory reception.

For the maturation of the functions of the left hemisphere, the normal course of ontogenesis of the right hemisphere is necessary. For example, it is known that phonemic hearing (distinction of meaning between speech sounds) is a function of the left hemisphere. But, before becoming a link in sound discrimination, it must be formed and automated as tonal sound discrimination in the right hemisphere with the help of the child’s comprehensive interaction with the world around him. Deficiency or immaturity of this link in the ontogenesis of phonemic hearing can lead to delays in speech development.

The development of the limbic system allows the child to establish social connections. Between the ages of 15 months and 4 years, primitive emotions are generated in the hypothalamus and amygdala: rage, fear, aggression. As neural networks develop, connections are formed with the cortical (cortical) parts of the temporal lobes, responsible for thinking, and more complex emotions with a social component appear: anger, sadness, joy, grief. With the further development of nerve networks, connections are formed with the front parts of the brain and such subtle feelings as love, altruism, empathy, and happiness develop.

The third stage (from 7 to 12-15 years) The formation of interhemispheric interaction occurs. After the maturation of the hypothalamic-diencephalic structures of the brain (brain stem), maturation of the right hemisphere begins, and then the left. The maturation of the corpus callosum, as already noted, is completed only by the age of 12-15 years. Normal brain maturation occurs from bottom to top, from the right hemisphere to the left, from the posterior parts of the brain to the front. Intensive growth of the frontal lobe begins no earlier than 8 years and ends by 12-15 years. In ontogenesis, the frontal lobe is the first to develop and the last to complete its development. The development of Broca's center in the frontal lobe makes it possible to process information through internal speech, which is much faster than with verbalization.

Specialization of the cerebral hemispheres occurs at different rates in each child. On average, the figurative hemisphere experiences a surge in dendritic growth at 4-7 years of age, and the logical hemisphere at 9-12 years of age. The more actively both hemispheres and all lobes of the brain are used, the more dendritic connections are formed in the corpus callosum and myelinated. The fully formed corpus callosum transmits 4 billion signals per second through 200 million nerve fibers, mostly myelinated, connecting the two hemispheres. Integration and rapid access to information stimulates the development of operational thinking and formal logic. Girls and women have more nerve fibers in the corpus callosum than boys and men, which provides them with higher compensatory mechanisms.

Myelination in different zones of the cortex also proceeds unevenly: in the primary fields it ends in the first half of life, in the secondary and tertiary fields it continues up to 10-12 years. Flexing's classic studies showed that myelination of the motor and sensory roots of the optic tract is completed in the first year after birth, the reticular formation - at 18 years, and the associative pathways - at 25 years. This means that first of all, those nerve pathways that play the most important role in the early stages of ontogenesis are formed. The process of myelination is closely correlated with the growth of cognitive and motor abilities during the preschool years.

By the time a child starts school (at age 7), his right hemisphere is developed, and the left hemisphere is updated only by age 9. In this regard, the education of younger schoolchildren should take place in a natural right-hemisphere way - through creativity, images, positive emotions, movement, space, rhythm, sensory sensations. Unfortunately, at school it is customary to sit still, not move, to learn letters and numbers linearly, to read and write on a plane, that is, in the left-hemisphere way. That is why teaching very soon turns into coaching and training the child, which inevitably leads to decreased motivation, stress and neuroses. At 7 years old, only “external” speech is well developed in a child, so he literally thinks out loud. He needs to read and think out loud until “inner” speech is developed. Translating thoughts into written speech is an even more complex process, involving many areas of the neocortex: the sensory, primary auditory, auditory association center, primary visual, motor speech, and cognitive centers. Integrated thought patterns are transmitted to the vocalization area and basal ganglia of the limbic system, which makes it possible to construct words in spoken and written language.

Age Stages of development of a brain area Functions From conception to 15 months Stem structures Basic survival needs - nutrition, shelter, protection, safety. Sensory development of the vestibular apparatus, hearing, tactile sensations, smell, taste, vision 15 months - 4.5 g Limbic system Development of the emotional and speech sphere, imagination, memory, mastery of gross motor skills 4.5-7 years Right (figurative) hemisphere Processing in the brain of a holistic picture based on images, movement, rhythm, emotions, intuition, external speech, integrated thinking 7-9 years old Left (logical) hemisphere Detailed and linear information processing, improving speech skills, reading and writing, counting, drawing, dancing , music perception, hand motor skills 8 years Frontal lobe Improving fine motor skills, developing inner speech, controlling social behavior. Development and coordination of eye movements: tracking and focusing 9-12 years old Corpus callosum and myelination Complex information processing by the whole brain 12-16 years old Hormonal surge Formation of knowledge about yourself, your body. Understanding the significance of life, the emergence of public interests 16-21 years old A holistic system of the intellect and body Planning the future, analyzing new ideas and opportunities 21 years old and beyond Intensive leap in the development of the nervous network of the frontal lobes Development of systems thinking, understanding higher-level causal relationships, improving emotions (altruism , love, empathy) and fine motor skills

The cranial nerves include: 1. Olfactory nerves (I) 2. Optic nerve (II) 3. Oculomotor nerve (III) 4. Trochlear nerve (IV) 5. Trigeminal nerve (V) 6. Abducens nerve (VI) 7. Facial nerve (VII) 8. Vestibulocochlear nerve (VIII) 9. Glossopharyngeal nerve (IX) 10. Vagus nerve (X) 11. Accessory nerve (XI) 12. Hypoglossal nerve (XII) Each cranial nerve is directed to a specific foramen of the base of the skull , through which it leaves its cavity.

Spinal cord (dorsal view): 1 - spinal ganglion; 2 - segments and spinal nerves of the cervical spinal cord; 3 - cervical thickening; 4 - segments and spinal nerves of the thoracic spinal cord; 5 - lumbar thickening; 6 - segments and spinal nerves of the lumbar region; 7 - segments and spinal nerves of the sacral region; 8 - terminal thread; 9 - coccygeal nerve The cervical thickening corresponds to the exit of the spinal nerves going to the upper extremities, the lumbar thickening corresponds to the exit of the nerves going to the lower extremities.

There are 31 segments in the spinal cord, each corresponding to one of the vertebrae. In the cervical region there are 8 segments, in the thoracic region - 12, in the lumbar and sacral regions - 5 each, in the coccygeal region - 1. A section of the brain with two pairs of roots extending from it is called a segment.

Shells of the spinal cord (cervical spine): 1 - spinal cord covered with a soft membrane; 2 - arachnoid membrane; 3 - dura mater; 4 - venous plexuses; 5 - vertebral artery; 6 - cervical vertebra; 7 - anterior root; 8 - mixed spinal nerve; 9 - spinal node; 10 - dorsal root The soft, or vascular, membrane contains branches of blood vessels, which then penetrate the spinal cord. It has two layers: the inner one, fused with the spinal cord, and the outer one. The arachnoid membrane is a thin connective tissue plate). Between the arachnoid and soft membranes there is a subarachnoid (lymphatic) space filled with cerebrospinal fluid. The dura mater is a long, spacious sac that encloses the spinal cord.

The dura mater is connected to the arachnoid in the area of the intervertebral foramina on the spinal ganglia, as well as at the attachment points of the dentate ligament. The dentate ligament, as well as the contents of the epidural, subdural and lymphatic spaces, protect the spinal cord from damage. Longitudinal grooves run along the surface of the spinal cord. These two grooves divide the spinal cord into right and left halves. Two rows of anterior and posterior roots extend from the sides of the spinal cord. Shells of the spinal cord in a cross section: 1 - dentate ligament; 2 - arachnoid membrane; 3 - posterior subarachnoid septum; 4 - subarachnoid space between the arachnoid and soft membranes; 5 - vertebra in cut; 6 - periosteum; 7 - dura mater; 8 - subdural space; 9 - epidural space

A cross-section of the spinal cord reveals gray matter that lies inward of the white matter and resembles the outline of the letter H or a butterfly with outstretched wings. Gray matter runs the entire length of the spinal cord around the central canal. White matter makes up the conductive apparatus of the spinal cord. White matter communicates the spinal cord with the overlying parts of the central nervous system. White matter lies on the periphery of the spinal cord. Diagram of a cross section of the spinal cord: 1 - oval fascicle of the posterior cord; 2 - posterior root; 3 - Roland's substance; 4 - posterior horn; 5 - front horn; 6 - anterior root; 7 - tectospinal tract; 8 - ventral corticospinal tract; 9 - ventral vestibulospinal tract; 10 - olivospinal tract; 11 - ventral spinocerebellar tract; 12 - lateral vestibulospinal tract; 13 - spinothalamic tract and tectospinal tract; 14 - rubrospinal tract; 15 - lateral corticospinal tract; 16 - dorsal spinocerebellar tract; 17 - Burdakh's path; 18 - Gaulle's path

Spinal nerves are paired (31 pairs), metamerically located nerve trunks: 1. Cervical nerves (CI-CVII), 8 pairs 2. Thoracic nerves (Th. I-Th. XII), 12 pairs 3. Lumbar nerves (LI- LV), 5 pairs 4. Sacral nerves (SI-Sv), 5 pairs 5. Coccygeal nerve (Co. I-Co II), 1 pair, less often two. The spinal nerve is mixed and is formed by the fusion of two roots belonging to it: the posterior root (sensitive), and the anterior root (motor).

Basic functions of the spinal cord The first function is reflex. The spinal cord independently carries out the motor reflexes of the skeletal muscles. Examples of some motor reflexes of the spinal cord are: 1) elbow reflex - tapping on the tendon of the biceps brachii muscle causes flexion in the elbow joint due to nerve impulses that are transmitted through the 5th-6th cervical segments; 2) knee reflex - tapping the tendon of the quadriceps femoris muscle causes extension in the knee joint due to nerve impulses that are transmitted through the 2nd-4th lumbar segments. The spinal cord is involved in many complex coordinated movements - walking, running, work and sports activities, etc. The spinal cord carries out autonomic reflexes to change the functions of internal organs - cardiovascular, digestive, excretory and other systems. Thanks to reflexes from proprioceptors in the spinal cord, motor and autonomic reflexes are coordinated. Reflexes are also carried out through the spinal cord from internal organs to skeletal muscles, from internal organs to receptors and other organs of the skin, from an internal organ to another internal organ.

The second function: conduction is carried out due to the ascending and descending tracts of white matter. Excitation from muscles and internal organs is transmitted through ascending pathways to the brain, and through descending pathways - from the brain to organs.

The spinal cord is more developed at birth than the brain. Cervical and lumbar enlargements of the spinal cord in newborns are not detected and begin to be contoured after 3 years of life. The rate of increase in the mass and size of the spinal cord is slower than that of the brain. The spinal cord mass doubles by 10 months, and triples by 3–5 years. The length of the spinal cord doubles by 7-10 years, and it increases somewhat more slowly than the length of the spine, so the lower end of the spinal cord moves upward with age.

The structure of the autonomic nervous system Part of the peripheral nervous system is involved in the conduction of sensory impulses and sends commands to the skeletal muscles - the somatic nervous system. Another group of neurons controls the activity of internal organs - the autonomic nervous system. The autonomic reflex arc consists of three links - sensitive, central and executive.

Structure of the autonomic nervous system The autonomic nervous system is divided into sympathetic, parasympathetic and metasympathetic divisions. The central part is formed by the bodies of neurons lying in the spinal cord and brain. These clusters of nerve cells are called autonomic nuclei (sympathetic and parasympathetic).

Department of Normal Physiology named after N.Yu. Belenkova Nizhny Novgorod State Medical Academy

Associate Professor Ph.D.

Prodius Petr Anatolievich

Lecture outline

1. The doctrine of higher nervous activity.

2. Classification of unconditioned and conditioned reflexes.

3. Conditions for the development of a conditioned reflex. Stages of formation of a conditioned reflex.

4. Mechanism of formation of temporary connection.

5. Dynamic stereotype.

6. Inhibition of conditioned reflexes.

7. The concept of signaling systems.

8. Types of higher nervous activity.

The doctrine of higher nervous activity

I.P. Pavlov divided behavior into lower (LNA) and higher nervous activity (HNA).

NND is a set of unconditioned reflexes that ensures the coordinated activity of all its systems and is aimed at maintaining homeostasis

VND is an integrative activity of the higher departments of the central nervous system, ensuring individual behavioral adaptation of humans and animals to changing conditions of the external and internal environment.

To study GNI, I.P. Pavlov developed the method of conditioned reflexes.

I.P. Pavlov introduced the term GNI as the equivalent of mental

ical activities.

Unconditioned and conditioned reflex

Unconditioned reflex– a constant, species-specific, stereotypical, genetically fixed reaction of the body to external or internal changes carried out with the participation of the central nervous system.

Example - Salivation in response to irritation of the oral cavity by food.

Conditioned reflex- a reaction of the body to a stimulus developed in ontogenesis that was previously indifferent to this reaction.

Example - Salivation by the sight and smell of food.

Based on the principle of biological significance:

Food - salivation;

Defensive – withdrawing a limb;

Sexual - choice of partner;

Parental - feeding offspring;

Gaming - ;

Indicative – indicative reflex;

Classification of unconditioned reflexes according to I.P. Pavlov

Based on the principle of the level of closure in the central nervous system:

Simple (spinal) – knee reflex;

Complicated (bulbar) - salivary -

ny reflex;

Complex (mesencephalic) - pupillary reflex;

The most complex (subcortical-cortical) – food-procuring instinct

Conditions for the development of a conditioned reflex

1 . Combination of indifferent, in the future

conditioned signal, with unconditional reinforcement.