Pavlov called the conditioned reflex activity of the cerebral cortex the signal activity of the brain, since stimuli from the external environment give the body signals about what is important to it in the surrounding world. Pavlov called the signals entering the brain that are caused by objects and phenomena acting on the senses (resulting in sensations, perceptions, ideas) the first signaling system; it is found in humans and animals. But in humans, as Pavlov writes, an extraordinary increase in the mechanisms of nervous activity occurred in the process of work and social life. This increase is human speech, and according to Pavlov’s theory, it is the second signaling system - verbal.

The first signaling system is visual, auditory and other sensory signals from which images of the external world are built. The perception of direct signals from objects and phenomena of the surrounding world and signals from the internal environment of the body, coming from visual, auditory, tactile and other receptors, constitutes the first signaling system that animals and humans have.

The second signaling system is verbal, in which the word as a conditioned stimulus, a sign that has no real physical content, but is a symbol of objects and phenomena of the material world, becomes a strong stimulus. This signaling system consists of the perception of words - heard, spoken (aloud or silently) and visible (when reading and writing).

With the help of a word, a transition is made from the sensory image of the first signaling system to the concept, representation of the second signaling system. The ability to operate with abstract concepts expressed in words that serve as the basis for mental activity.

For the second signaling system to begin to function, the child needs to communicate with other people and acquire oral and written language skills, which takes a number of years. If a child is born deaf or loses his hearing before he begins to speak, then the ability of oral speech inherent in him is not used and the child remains mute, although he can pronounce sounds. In the same way, if a person is not taught to read and write, then he will forever remain illiterate. All this indicates the decisive influence of the environment on the development of the second signaling system. The latter is associated with the activity of the entire cerebral cortex, but some areas of it play a special role in speech. These areas of the cortex are the cores of speech analyzers.

Physiological foundations of speech. The activity of the second signaling system is ensured by the function of the motor, auditory and visual analyzers and the frontal parts of the brain. The regulation of speech is associated with the triggering and regulatory role of the cortex, which receives afferent impulses from the receptors of the muscles, tendons and ligaments of the vocal apparatus and respiratory muscles. The cortical nucleus of the speech motor analyzer is located in the area of ​​the second and third frontal gyri - Broca's speech motor center. Speech perception occurs with the help of speech-motor and speech-auditory analyzers (Wernicke's center).

Both signaling systems are in constant interaction. If the signals of the second signal system (words) do not have support in the first signal system (do not reflect what was received through it), then they become incomprehensible. Thus, a word in a foreign language that we do not know does not tell us anything, since this word has no specific content for us. But the first signals alone do not provide deep and complete knowledge about the world. Only with the help of the second signaling system (speech) did a person learn to expand his information, generalizing individual facts, establishing patterns that were important to him.

Thanks to the second signaling system, people deepen and retain their knowledge.

Pavlov considered the second signaling system to be the “highest regulator of human behavior”, which prevails over the first signaling system. But the latter, to a certain extent, controls the activity of the second signaling system. This allows a person to control his unconditioned reflexes and restrain a significant part of the body’s instinctive manifestations and emotions. A person can consciously suppress defensive (even in response to painful stimuli), food and sexual reflexes. At the same time, the subcortical formations and nuclei of the brain stem, especially the reticular formation, are sources (generators) of impulses that maintain normal brain tone

awakening suppresses all others and determines the nature of the body's response.

There are several types of internal inhibition: extinction, differentiation, delayed and conditioned inhibition. If an animal with a developed reflex to light is presented with a conditioned stimulus for a long time without reinforcing it with an unconditioned stimulus (food), after some time salivation and juice secretion to light will no longer occur. This is the so called extinction internal inhibition conditioned reflex. In this case, temporary connections between the centers of analyzers and unconditioned reflexes are weakened or even disappear completely. Differential braking

develops when stimuli that are close in parameters to the conditioned stimulus are not reinforced. For example, an animal has developed a salivary reflex to a certain sound signal. Presentation of another sound signal, not very different from the first, without reinforcement with food will lead to the fact that the animal will stop responding to the original conditioned stimulus. Delayed braking occurs with a gradual increase in the interval between the conditioned stimulus and the reinforcement with food. A conditioned inhibitor is produced by the alternating presentation of a reinforced and non-reinforced conditioned stimulus. In this case, the latter is preceded by additional irritation. After some time, additional irritation causes the cessation of salivation and juice secretion to the conditioned stimulus.

16.2. The concept of the first and second signaling systems

The higher nervous activity of humans differs from that of animals. Animal behavior is much simpler than human behavior. Based on this, I.P. Pavlov developed the doctrine of the first and second signal systems.

First signaling system exists in both animals and humans. It provides specific objective thinking, i.e. analysis and synthesis of specific signals from objects and phenomena of the external world entering the brain through sensory organ receptors.

Second signaling system only available to humans. Its occurrence is associated with the development of speech. When pronouncing words are perceived by the organ of hearing or when reading, an association arises with some object or action that the word denotes. Thus the word is a symbol. The second signaling system is associated with the assimilation of information that comes in the form of symbols, primarily words. It makes abstract thinking possible. The first and second signaling systems are in close and constant interaction in humans.

sti. The second signaling system appears in the child later than the first. Its development is associated with learning to speak and write.

Speech is a unique human ability to symbolically reflect objects in the surrounding world. It is speech that forms, in the words of I. P. Pavlov, “specially human higher thinking.” It is the word that is the “signal of signals”, i.e. in that it can evoke an idea of ​​an object without its presentation. Speech makes learning possible without direct reference to the subjects being studied. It is the highest function of the central nervous system, primarily the cerebral cortex.

Speech is divided into oral and written. Each of them has its own cortical centers. Oral speech is understood as the pronunciation of certain words or other sound signals that have a certain subject meaning. Written speech consists of transmitting any information in the form of printed symbols (letters, hieroglyphs and other signs) on a certain medium (paper, parchment, magnetic media, etc.). The development of speech in a child is a complex and lengthy process. Between the ages of 1 and 5 years, a child learns to communicate using words. By the age of 5 - 7 years, it is possible to master writing and counting skills.

Thus, the first signaling system implies the acquisition of certain life skills through direct interaction with the environment without conscious transfer of the acquired life experience from one generation to another. The second signaling system consists in the perception of the surrounding world, both in direct contact with it and through the comprehension of various information received about it. This information can be transmitted from one individual to another, from generation to generation.

16.3. Electroencephalography

Electroencephalography (EEG) is a method of recording the bioelectrical activity of the brain. When performing this study, electrodes are placed on the scalp that sense fluctuations in electrical potentials in the brain. Subsequently, these changes intensify by 1 - 2 million times

And are registered using special devices on a medium (for example, paper). The bioelectrical activity of the brain recorded using EEG, as a rule, has a wave character (Fig. 16.1). These waves have different shapes, frequencies

And amplitude. In a healthy person, they predominateα waves (alpha waves). Their frequency fluctuates between 8-12 oscillations per second, amplitude 10 - 50 µV (up to 100 µV). β-Waves (beta waves)

Rice. 16.1. Electroencephalogram of a person during periods of wakefulness and sleep:

A - EEG in a state of wakefulness; b - EEG in a state of slow-wave sleep;

V - EEG in a state of fast-wave sleep

have a frequency of 15 - 32 vibrations per second, but their amplitude is several times less than that of a-waves. At rest, α waves predominate in the posterior regions of the brain, while P waves are localized primarily in the frontal regions. Slow δ waves (delta waves) and θ waves (theta waves) appear in healthy adults at the moment of falling asleep. Their frequency is 0.5 - 3 oscillations per second for 8-waves and 4-7 oscillations per second for θ-waves. The amplitude of slow rhythms is 100 - 300 µV.

The electroencephalography method is widely used in clinical practice. With its help, it is possible to establish the side of the brain lesion, the presumable localization of the pathological focus, and distinguish a diffuse pathological process from a focal one. The value of the method in the diagnosis of epilepsy is invaluable.

16.4. Types of higher nervous activity

Each person is individual. All people differ from each other not only in physical qualities, but also in mental characteristics. The psyche is a reflection of a person’s inner world. The basis of its existence is the brain. It is he who ensures the totality of processes that form the psyche. The result of mental activity is a person’s behavior, his reactions to certain situations.

Hippocrates also noted the differences between people in their behavior. He associated this with the predominance of one or another “liquid” in the body

bones": blood, mucus, bile and black bile. It has now been established that these differences in behavior are due to the types of higher nervous activity. However, it should be noted that the functioning of the nervous system, and therefore the type of higher nervous activity, also depends on humoral factors - the level of hormones and biologically active substances in the blood.

Type of higher nervous activity - predominantly innate individual properties of the functioning of the central nervous system. This concept should not be confused with the concept temperament , which is a manifestation in human behavior of the type of his higher nervous activity. Moreover, the first concept is a physiological concept, and the second is more psychological. I.P. Pavlov believed that the main types of higher nervous activity coincide with the four types of temperament established by Hippocrates.

Features of nervous processes, properties of higher nervous activity determine such concepts as strength, balance and mobility. Strength is determined by the intensity of the processes of excitation and inhibition in the brain. Equilibrium characterized by their relationship with each other. Mobility is the possibility of changing excitation processes by inhibition processes.

Based on strength, higher nervous activity is divided into strong

And weak types, according to balance - into balanced and unbalanced, according to mobility - into mobile and inert.

IN Depending on the characteristics of nervous processes, four main types of higher nervous activity and four types of temperament are distinguished.

How do different types of higher nervous activity relate?

And temperaments can be seen from the table. 16.2.

What traits characterize each of the types of temperament identified here? Cholerics are explosive, very emotional people with easy mood swings, extremely active, energetic, characterized by a quick reaction to various stimuli. Sangvi-

The signaling system is a set of processes in the nervous system that perceive, analyze information and respond to the body.. Physiologist I.P. Pavlov developed the doctrine of the first and second signal systems. First signaling system he named the activity of the cerebral cortex, which is associated with the perception through receptors of direct stimuli (signals) of the external environment, for example, light, heat, pain, etc. It is the basis for the development of conditioned reflexes and is characteristic of both animals and humans.

Man, unlike animals, is also characterized by second signaling system, associated with the function of speech, with the word, audible or visible (written speech). The word, according to I.P. Pavlov, is a signal for the operation of the first signaling system (“signal of signals”). For example, a person’s actions will be the same in response to the word “fire” and the fire actually observed (visual irritation) by him. The formation of a conditioned reflex based on speech is a qualitative feature of human higher nervous activity. The second signaling system was formed in humans in connection with the social way of life and collective work, in which it is a means of communication with each other. Words, speech, writing are not only an auditory or visual stimulus, they carry certain information about an object or phenomenon. In the process of learning speech in a person, temporary connections arise between cortical neurons that perceive signals from various objects, phenomena and events, and centers that perceive the verbal designation of these objects, phenomena and events, their semantic meaning. That is why, after a person has formed a conditioned reflex to some stimulus, it is easily reproduced without reinforcement, if this stimulus is expressed verbally. For example, in response to the phrase “iron is hot,” a person will withdraw his hand from it. A dog can also develop a conditioned reflex to a word, but it perceives it as a certain sound combination, without understanding the meaning.

Verbal signaling in humans has made it possible for an abstract and generalized perception of phenomena that are expressed in concepts, judgments and inferences. For example, the word “trees” generalizes numerous tree species and distracts from the specific characteristics of each tree species. The ability to generalize and abstract is the basis thinking person. Thanks to abstract logical thinking, a person learns about the world around him and its laws. The ability to think is used by a person in his practical activities, when he sets certain goals, outlines ways of implementation and achieves them. In the course of the historical development of mankind, thanks to thinking, enormous knowledge about the external world has been accumulated.

Thus, thanks to the first signaling system, a specifically sensory perception of the surrounding world and the state of the organism itself is achieved. The development of the second signaling system provided an abstractly generalized perception of the external world in the form of concepts, judgments, and conclusions. These two signaling systems closely interact with each other, since the second signaling system arose on the basis of the first and functions in connection with it. In humans, the second signaling system prevails over the first due to the social way of life and developed thinking.

FEATURES OF HUMAN HIGHER NERVOUS ACTIVITY.

There are first and second signaling systems.

First signaling system available in humans and animals. The activity of this system is manifested in conditioned reflexes that are formed to any stimulation of the external environment (light, sound, mechanical stimulation, etc.), with the exception of words. In a person living in certain social conditions, the first signaling system has a social connotation.

Conditioned reflexes of the first signaling system are formed as a result of the activity of cells in the cerebral cortex, except for the frontal region and the region of the cerebral speech motor analyzer. The first signaling system in animals and humans provides objective, concrete thinking.

The second signaling system arose and developed as a result of human labor activity and the emergence of speech. Work and speech contributed to the development of hands, brain and sense organs.

Operation of the second signaling system manifests itself in speech conditioned reflexes. We may not see an object at the moment, but its verbal designation is enough for us to clearly imagine it. The second signaling system provides abstract thinking in the form of concepts, judgments, and conclusions.

Speech reflexes of the second signaling system are formed due to the activity of neurons in the frontal regions and the region of the speech motor analyzer. The peripheral section of this analyzer is represented by receptors that are located in the word-pronouncing organs (receptors of the larynx, soft palate, tongue, etc.). From the receptors, impulses travel along the corresponding afferent pathways to the cerebral part of the speech motor analyzer, which is a complex structure that includes several zones of the cerebral cortex. The function of the speech motor analyzer is especially closely related to the activity of the motor, visual and sound analyzers. Speech reflexes, like ordinary conditioned reflexes, obey the same laws. However, the word differs from the stimuli of the first signaling system in that it is comprehensive. A kind word spoken at the right time promotes a good mood and increases productivity, but a word can seriously injure a person. This especially applies to relationships between sick people and health care workers. A carelessly spoken word in the presence of a patient regarding his illness can significantly worsen his condition.

Animals and humans are born only with unconditioned reflexes. In the process of growth and development, the formation of conditioned reflex connections of the first signaling system, the only one in animals, occurs. In the future, on the basis of the first signal system, connections of the second signal system are gradually formed in a person, when the child begins to speak and learn about the surrounding reality.

The second signaling system is the highest regulator of various forms of human behavior in the natural and social environment around him.

However, the second signaling system correctly reflects the external objective world only if its consistent interaction with the first signaling system is constantly maintained.

In the first signaling system, all forms of behavior are based on direct perception of reality and reactions in response to immediate (natural) stimuli. A person perceives the outside world based on the activity of the first signaling system. Consequently, the analysis and synthesis of specific signals, objects and phenomena of the external world that make up the first signal system are common to animals and humans.

In the process of human development, an “extraordinary increase” in the mechanisms of brain function appeared. This is the second signaling system of reality, the specific stimulus of which is a word with an inherent meaning, a word that denotes objects and phenomena of the surrounding world. By the second signal system of reality, I.P. Pavlov understood the nervous processes that arise in the cerebral hemispheres as a result of the perception of signals from the surrounding world in the form of speech designations of objects and phenomena of nature and society. The word is perceived by a person as heard (auditory analyzer), as written (visual analyzer) or as spoken (motor analyzer). In all cases, these stimuli are united by the meaning of the word. Words acquire meaning as a result of the emergence of a strong connection in the cerebral cortex between the excitation centers that arise under the influence of specific objects in the surrounding world, and the excitation centers that arise when spoken aloud, denoting specific objects or actions. As a result of the formation of such connections, words can replace a specific environmental stimulus and become its symbol.

The emergence of the second signaling system introduced a new principle into the activity of the human brain. The word, as a signal of signals, makes it possible to escape from specific objects and phenomena. The development of verbal signaling has made generalization and distraction possible, which is expressed in phenomena characteristic of humans - thinking and concepts.

The ability to think through abstract (abstract) images, concepts expressed in spoken or written words, made possible the emergence of abstract-generalized thinking.

So, the second human signaling system is the basis of purely human verbal-logical thinking, the basis for the formation of knowledge about the world around us through verbal abstractions and the basis of human consciousness.

In every human behavioral act, the participation of three types of interneuron connections is revealed: 1) unconditioned reflex; 2) temporary connections of the first signaling system; 3) temporary connections of the second signaling system. An analysis of the physiological mechanisms of human behavior shows that it is the result of the joint activity of both signaling systems, subcortical and brain stem formations.

The second signaling system, as the highest regulator of human behavior, prevails over the first and to some extent suppresses it. At the same time, the first signaling system to a certain extent determines the activity of the second.

Both signaling systems (the states of which are determined by the function of the cerebral cortex as a whole) are closely related to the activity of subcortical centers. A person can voluntarily inhibit his unconditioned reflex reactions, restrain many manifestations of instincts and emotions. It can suppress defensive (in response to painful stimuli), food, and sexual reflexes. At the same time, the subcortical nuclei, nuclei of the brain stem and reticular formation are sources of impulses that maintain the normal tone of the cerebral cortex.