Salivation in a person will certainly be a reflex reaction. Conditioned and unconditioned reflexes

Reflex- this is the body’s response to irritation from the external or internal environment, carried out with the help of the central nervous system. There are unconditioned and conditioned reflexes.

Unconditioned reflexes- these are congenital, permanent, hereditarily transmitted reactions characteristic of representatives of a given type of organism. For example, pupillary, knee, Achilles and other reflexes. Unconditioned reflexes ensure the interaction of the organism with the external environment, its adaptation to environmental conditions and create conditions for the integrity of the organism. Unconditioned reflexes arise immediately after the action of a stimulus, since they are carried out along ready-made, inherited reflex arcs, which are always constant. Complex unconditioned reflexes are called instincts.
To the number without conditioned reflexes include sucking and motor, which are already inherent in an 18-week fetus. Unconditioned reflexes are the basis for the development of conditioned reflexes in animals and humans. In children, with age, they turn into synthetic complexes of reflexes, which increases the body’s adaptability to the external environment.

Conditioned reflexes- reactions are adaptive, temporary and strictly individual. They are inherent only in one or several representatives of the species, subjected to training (training) or influence natural environment. Conditioned reflexes are developed gradually, in the presence of a certain environment, and are a function of the normal, mature cortex of the cerebral hemispheres and lower parts of the brain. In this regard, conditioned reflexes are related to unconditioned ones, since they are a response of the same material substrate - nervous tissue.

If the conditions for the development of reflexes are constant from generation to generation, then the reflexes can become hereditary, that is, they can turn into unconditioned. An example of such a reflex is the opening of the beak of blind and fledgling chicks in response to the shaking of the nest by a bird flying in to feed them. Since shaking the nest is followed by feeding, which was repeated in all generations, the conditioned reflex becomes unconditioned. However, all conditioned reflexes are adaptive reactions to a new external environment. They disappear when the cerebral cortex is removed. Higher mammals and humans with damage to the cortex become deeply disabled and die in the absence of the necessary care.

Numerous experiments conducted by I.P. Pavlov showed that the basis for the development of conditioned reflexes is formed by impulses arriving along afferent fibers from extero- or interoreceptors. For their formation, the following conditions are necessary: ​​1) the action of an indifferent (future conditioned) stimulus must precede the action of an unconditioned stimulus. With a different sequence, the reflex is not developed or is very weak and quickly fades away; 2) for a certain time, the action of the conditioned stimulus must be combined with the action of the unconditioned stimulus, that is, the conditioned stimulus is reinforced by the unconditioned. This combination of stimuli should be repeated several times. In addition, a prerequisite for the development of a conditioned reflex is the normal function of the cerebral cortex, the absence of painful processes in the body and extraneous stimuli.
Otherwise, in addition to the reinforced reflex being developed, an indicative or reflex of the internal organs (intestines, Bladder and etc.).

An active conditioned stimulus always causes a weak focus of excitation in the corresponding area of ​​the cerebral cortex. The unconditioned stimulus that is connected (after 1-5 s) creates a second, stronger focus of excitation in the corresponding subcortical nuclei and the area of ​​the cerebral cortex, which distracts the impulses of the first (conditioned) weaker stimulus. As a result, a temporary connection is established between both foci of excitation of the cerebral cortex. With each repetition (i.e. reinforcement), this connection becomes stronger. The conditioned stimulus turns into a conditioned reflex signal. To develop a conditioned reflex, a conditioned stimulus of sufficient strength and high excitability of the cells of the cerebral cortex, which must be free from external stimuli, are necessary. Compliance with the above conditions accelerates the development of a conditioned reflex.

Depending on the method of development, conditioned reflexes are divided into secretory, motor, vascular, reflexes of changes in internal organs, etc.

A reflex developed by reinforcing a conditioned stimulus with an unconditioned one is called a first-order conditioned reflex. Based on it, you can develop a new reflex. For example, by combining a light signal with feeding, a dog has developed a strong conditioned salivation reflex. If you give a bell (sound stimulus) before the light signal, then after several repetitions of this combination the dog begins to salivate in response to the sound signal. This will be a second-order reflex, or secondary, reinforced not by an unconditioned stimulus, but by a first-order conditioned reflex. When developing conditioned reflexes of higher orders, it is necessary that a new indifferent stimulus is turned on 10-15 s before the onset of the conditioned stimulus of a previously developed reflex. If the stimulus acts at intervals that are closer or combined, then a new reflex will not appear, and the previously developed one will fade away, as inhibition will develop in the cerebral cortex. Repeated repetition of jointly acting stimuli or a significant overlap of the time of action of one stimulus on another causes the appearance of a reflex to a complex stimulus.

A certain period of time can also become a conditioned stimulus for developing a reflex. People have a temporary reflex to feel hungry during the hours when they usually eat. Intervals can be quite short. In children school age reflex for time - weakening of attention before the end of the lesson (1-1.5 minutes before the bell). This is the result not only of fatigue, but also of the rhythmic functioning of the brain during training sessions. The reaction to time in the body is the rhythm of many periodically changing processes, for example, breathing, cardiac activity, awakening from sleep or hibernation, molting of animals, etc. Its occurrence is based on the rhythmic sending of impulses from the corresponding organs to the brain and back to the effector organs devices.

Reflex– the body’s response is not an external or internal irritation, carried out and controlled by the central nervous system. The development of ideas about human behavior, which has always been a mystery, was achieved in the works of Russian scientists I. P. Pavlov and I. M. Sechenov.

Reflexes unconditioned and conditioned.

Unconditioned reflexes- This innate reflexes, which are inherited by offspring from their parents and persist throughout a person’s life. The arcs of unconditioned reflexes pass through the spinal cord or brain stem. The cerebral cortex is not involved in their formation. Unconditioned reflexes ensure the organism's adaptation only to those changes in the environment that have often been encountered by many generations of a given species.

TO unconditioned reflexes relate:

Food (salivation, sucking, swallowing);
Defensive (coughing, sneezing, blinking, withdrawing your hand from a hot object);
Indicative (squinting eyes, turning the head);
Sexual (reflexes associated with reproduction and care of offspring).
The importance of unconditioned reflexes lies in the fact that thanks to them the integrity of the body is preserved, the internal environment is maintained constancy and reproduction occurs. Already in a newborn child the simplest unconditioned reflexes are observed.
The most important of these is the sucking reflex. The stimulus of the sucking reflex is the touching of an object to the child’s lips (mother’s breast, pacifier, toy, finger). The sucking reflex is an unconditioned food reflex. In addition, the newborn already has some protective unconditioned reflexes: blinking, which occurs if a foreign body approaches the eye or touches the cornea, constriction of the pupil when exposed to strong light on the eyes.

Particularly pronounced unconditioned reflexes in various animals. Not only individual reflexes can be innate, but also more complex forms of behavior, which are called instincts.

Conditioned reflexes– these are reflexes that are easily acquired by the body throughout life and are formed on the basis of an unconditioned reflex under the action of a conditioned stimulus (light, knock, time, etc.). I.P. Pavlov studied the formation of conditioned reflexes in dogs and developed a method for obtaining them. To develop a conditioned reflex, a stimulus is needed - a signal that triggers the conditioned reflex; repeated repetition of the action of the stimulus allows you to develop a conditioned reflex. During the formation of conditioned reflexes, a temporary connection arises between the centers of the analyzers and the centers of the unconditioned reflex. Now this unconditioned reflex is not carried out under the influence of completely new external signals. These stimuli from the surrounding world, to which we were indifferent, can now acquire vital significance. Throughout life, many conditioned reflexes are developed that form the basis of our life experience. But this vital experience has meaning only for a given individual and is not inherited by its descendants.

In a separate category conditioned reflexes distinguish motor conditioned reflexes developed during our lives, i.e. skills or automated actions. The meaning of these conditioned reflexes is to master new motor skills and develop new forms of movements. During his life, a person masters many special motor skills related to his profession. Skills are the basis of our behavior. Consciousness, thinking, attention are freed from performing those operations that have become automated and become skills Everyday life. The most successful way to master skills is through systematic exercises, correction of errors noticed in time, knowledge ultimate goal each exercise.

If you do not reinforce the conditioned stimulus with the unconditioned stimulus for some time, then inhibition of the conditioned stimulus occurs. But it doesn't disappear completely. When the experience is repeated, the reflex is restored very quickly. Inhibition is also observed when exposed to another stimulus of greater strength.

8. The individuality of conditioned reflexes is manifested in the fact that 1) an individual inherits only certain conditioned reflexes 2) each individual of the same species has its own life experience 3) they are formed on the basis of individual unconditioned reflexes 4) each individual individual mechanism formation of a conditioned reflex

• 20-09-2010 15:22
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Each person, as well as all living organisms, has a number of vital needs: food, water, comfortable conditions. Everyone has instincts of self-preservation and continuation of their kind. All mechanisms aimed at satisfying these needs are laid down at the genetic level and appear simultaneously with the birth of the organism. These are innate reflexes that help to survive.

The concept of an unconditioned reflex

The word reflex itself is not something new and unfamiliar for each of us. Everyone has heard it in their life, and quite many times. This term was introduced into biology by I. P. Pavlov, who devoted a lot of time to studying nervous system.

According to the scientist, unconditioned reflexes arise under the influence of irritating factors on the receptors (for example, withdrawing a hand from a hot object). They contribute to the body’s adaptation to those conditions that remain practically unchanged.

This is the so-called product of the historical experience of previous generations, therefore it is also called a species reflex.

We live in a changing environment; it requires constant adaptations, which cannot in any way be provided for by genetic experience. Unconditioned reflexes of a person are constantly either inhibited, then modified or arise again, under the influence of those stimuli that surround us everywhere.

Thus, already familiar stimuli acquire the qualities of biologically significant signals, and the formation of conditioned reflexes occurs, which form the basis of our individual experience. This is what Pavlov called higher nervous activity.

Properties of unconditioned reflexes

The characteristics of unconditioned reflexes include several mandatory points:

1. Congenital reflexes are inherited.
2. They appear equally in all individuals of a given species.
3. For a response to occur, the influence of a certain factor is necessary, for example, for the sucking reflex it is irritation of the lips of a newborn.
4. The area of ​​perception of the stimulus always remains constant.
5. Unconditioned reflexes have a constant reflex arc.
6. They persist throughout life, with some exceptions in newborns.

The meaning of reflexes

All our interaction with the environment is built at the level of reflex responses. Unconditioned and conditioned reflexes play an important role in the existence of the organism.

In the process of evolution, a division occurred between those aimed at the survival of the species and those responsible for adaptability to constantly changing conditions.

Congenital reflexes begin to appear in utero, and their role boils down to the following:

• Maintaining internal environment indicators at a constant level.
• Preserving the integrity of the body.
• Preservation of a species through reproduction.

The role of innate reactions immediately after birth is great; they ensure the survival of the baby in completely new conditions.

The body lives surrounded external factors, which are constantly changing and need to be adapted to. This is where the highest comes to the fore nervous activity in the form of conditioned reflexes.

For the body they have the following meaning:

• We will improve the mechanisms of its interaction with the environment.
• The processes of contact between the body and the external environment are clarified and complicated.
• Conditioned reflexes are an indispensable basis for the processes of learning, education and behavior.

Thus, unconditioned and conditioned reflexes are aimed at maintaining the integrity of a living organism and the constancy of the internal environment, as well as effective interaction with the outside world. Between themselves they can be combined into complex reflex acts that have a certain biological orientation.

Classification of unconditioned reflexes

Hereditary reactions of the body, despite their innateness, can differ greatly from each other. It is not at all surprising that the classification can be different, depending on the approach.

Pavlov also divided all unconditioned reflexes into:

• Simple (the scientist included the sucking reflex among them).
• Complex (sweating).
• The most complex unconditioned reflexes. A variety of examples can be given: food reactions, defensive reactions, sexual reactions.

Currently, many adhere to a classification based on the meaning of reflexes. Depending on this, they are divided into several groups:

The first group of reactions has two characteristics:

1. If they are not satisfied, this will lead to the death of the body.
2. Satisfaction does not require the presence of another individual of the same species.

The third group also has its own characteristic features:

1. Self-development reflexes have nothing to do with the body’s adaptation to a given situation. They are aimed at the future.
2. They are completely independent and do not stem from other needs.

We can also divide them according to their level of complexity, then the following groups will appear before us:

1. Simple reflexes. These are the body's normal responses to external stimuli. For example, withdrawing your hand from a hot object or blinking when a speck gets into your eye.
2. Reflex acts.
3. Behavioral reactions.
4. Instincts.
5. Imprinting.

Each group has its own characteristics and differences.

Reflex acts

Almost all reflex acts are aimed at ensuring the vital functions of the body, so they are always reliable in their manifestation and cannot be corrected.

These include:

• Breath.
• Swallowing.
• Vomiting.

In order to stop a reflex act, you simply need to remove the stimulus that causes it. This can be practiced when training animals. If you want natural needs not to distract from training, then you need to walk the dog before this, this will eliminate the irritant that can provoke a reflex act.

Behavioral reactions

This type of unconditioned reflex can be well demonstrated in animals. Behavioral reactions include:

• The dog's desire to carry and pick up objects. Retrieval reaction.
• Showing aggression when seen stranger. Active defensive reaction.
• Finding objects by smell. Olfactory-search reaction.

It is worth noting that a behavioral reaction does not mean that the animal will certainly behave this way. What is meant? For example, a dog that has a strong active-defensive reaction from birth, but is physically weak, most likely will not show such aggression.

These reflexes can determine the animal's actions, but they can be controlled. They should also be taken into account when training: if an animal completely lacks an olfactory-search reaction, then it is unlikely that it will be possible to train it as a search dog.

Instincts

There are also more complex forms in which unconditioned reflexes appear. Instincts come into play here. This is a whole chain of reflex acts that follow each other and are inextricably interconnected.

All instincts are associated with changing internal needs.

When a child is just born, his lungs practically do not function. The connection between him and his mother is interrupted by cutting the umbilical cord, and carbon dioxide accumulates in the blood. It begins its humoral effect on the respiratory center, and instinctive inhalation occurs. The child begins to breathe independently, and the first cry of the baby is a sign of this.

Instincts are a powerful stimulant in human life. They may well motivate success in a certain field of activity. When we stop controlling ourselves, instincts begin to guide us. As you yourself understand, there are several of them.

Most scientists are of the opinion that there are three basic instincts:

1. Self-preservation and survival.
2. Continuation of the family.
3. Leadership instinct.

All of them can generate new needs:

• In safety.
• In material prosperity.
• Looking for a sexual partner.
• In caring for children.
• In influencing others.

We could go on and on about the types of human instincts, but, unlike animals, we can control them. For this purpose, nature has endowed us with reason. Animals survive only due to instincts, but for this we are also given knowledge.

Don't let your instincts get the better of you, learn to manage them and become the master of your life.

Imprint

This form of unconditioned reflex is also called imprinting. There are periods in the life of every individual when the entire surrounding environment is imprinted on the brain. For each species, this time period may be different: for some it lasts several hours, and for others it lasts several years.

Remember how easily young children master foreign speech skills. While schoolchildren put a lot of effort into this.

It is thanks to imprinting that all babies recognize their parents and distinguish individuals of their species. For example, after the birth of a baby, a zebra spends several hours alone with it in a secluded place. This is exactly the time that is necessary for the cub to learn to recognize its mother and not confuse her with other females in the herd.

This phenomenon was discovered by Konrad Lorenz. He conducted an experiment with newborn ducklings. Immediately after the hatching of the latter, he presented them with various objects, which they followed like a mother. They even perceived him as a mother, and followed him around.

Everyone knows the example of hatchery chickens. Compared to their relatives, they are practically tame and are not afraid of humans, because from birth they see him in front of them.

Congenital reflexes of an infant

After birth, the baby goes through a complex developmental path that consists of several stages. The degree and speed of mastery of various skills will directly depend on the state of the nervous system. The main indicator of its maturity is the unconditioned reflexes of the newborn.

The presence of them in the baby is checked immediately after birth, and the doctor makes a conclusion about the degree of development of the nervous system.

From the huge number of hereditary reactions, the following can be distinguished:

1. Kussmaul search reflex. When the area around the mouth is irritated, the child turns his head towards the irritant. The reflex usually fades by 3 months.
2. Sucking. If you place your finger in the baby's mouth, he begins to perform sucking movements. Immediately after feeding, this reflex fades away and becomes more active after some time.
3. Palmo-oral. If you press on the child's palm, he opens his mouth slightly.
4. Grasping reflex. If you put your finger in the baby’s palm and lightly press it, a reflexive squeezing and holding occurs.
5. The inferior grasp reflex is caused by light pressure on the front of the sole. The toes flex.
6. Crawling reflex. When lying on the stomach, pressure on the soles of the feet causes a crawling movement forward.
7. Protective. If you lay a newborn on his stomach, he tries to raise his head and turns it to the side.
8. Support reflex. If you take a baby under the armpits and place him on something, he will reflexively straighten his legs and rest on his entire foot.

The unconditioned reflexes of a newborn can go on for a long time. Each of them symbolizes the degree of development of certain parts of the nervous system. After an examination by a neurologist in the maternity hospital, a preliminary diagnosis of some diseases can be made.

From the point of view of their significance for the baby, the mentioned reflexes can be divided into two groups:

1. Segmental motor automatisms. They are provided by segments of the brain stem and spinal cord.
2. Posotonic automatisms. Provide regulation of muscle tone. The centers are located in the midbrain and medulla oblongata.

Oral segmental reflexes

This type of reflexes includes:

• Sucking. Appears during the first year of life.
• Search. Extinction occurs at 3-4 months.
• Proboscis reflex. If you hit a baby on the lips with your finger, he pulls them out into his proboscis. After 3 months, extinction occurs.
• The hand-mouth reflex is a good indicator of the development of the nervous system. If it does not appear or is very weak, then we can talk about damage to the central nervous system.

Spinal motor automatisms

Many unconditioned reflexes belong to this group. Examples include the following:

• Moro reflex. When a reaction is caused, for example, by hitting the table near the baby's head, the latter's arms are spread to the sides. Appears up to 4-5 months.
• Automatic gait reflex. When supported and slightly tilted forward, the baby makes stepping movements. After 1.5 months it begins to fade.
• Galant reflex. If you run your finger along the paravertebral line from the shoulder to the buttocks, the body bends towards the stimulus.

Unconditioned reflexes are assessed on a scale: satisfactory, increased, decreased, absent.

Differences between conditioned and unconditioned reflexes

Sechenov also argued that in the conditions in which the body lives, innate reactions are completely insufficient for survival; the development of new reflexes is required. They will help the body adapt to changing conditions.

How do unconditioned reflexes differ from conditioned reflexes? The table demonstrates this well.

Despite the obvious difference between conditioned reflexes and unconditioned ones, together these reactions ensure the survival and preservation of the species in nature.

Unconditioned reflexes are constant innate reactions of the body to certain influences from the external world, carried out through the nervous system and do not require special conditions for their occurrence.

All unconditioned reflexes, according to the degree of complexity and severity of the body’s reactions, are divided into simple and complex; depending on the type of reaction - to food, sexual, defensive, orientation-exploratory, etc.; depending on the animal’s attitude to the stimulus - into biologically positive and biologically negative. Unconditioned reflexes arise mainly under the influence of contact irritation: food unconditioned reflex - when food enters and is exposed to the tongue; defensive - when pain receptors are irritated. However, the emergence of unconditioned reflexes is also possible under the influence of such stimuli as the sound, sight and smell of an object. Thus, the sexual unconditioned reflex occurs under the influence of a specific sexual stimulus (sight, smell and other stimuli emanating from a female or male). The approximate exploratory unconditioned reflex always occurs in response to a sudden, little-known stimulus and usually manifests itself in turning the head and moving the animal towards the stimulus. Its biological meaning lies in the examination of a given stimulus and the entire external environment.

Complex unconditioned reflexes include those that are cyclical in nature and are accompanied by various emotional reactions (see). Such reflexes are often referred to as (see).

Unconditioned reflexes serve as the basis for the formation of conditioned reflexes. Violation or distortion of unconditioned reflexes is usually associated with organic lesions of the brain; the study of unconditioned reflexes is carried out to diagnose a number of diseases of the central nervous system (see Pathological reflexes).

Unconditioned reflexes (specific, innate reflexes) are innate reactions of the body to certain influences of the external or internal environment, carried out through the central nervous system and not requiring special conditions for their occurrence. The term was introduced by I.P. Pavlov and means that the reflex certainly occurs if adequate stimulation is applied to a certain receptor surface. The biological role of unconditioned reflexes is that they adapt an animal of a given species in the form of appropriate acts of behavior to constant, habitual environmental factors.

The development of the doctrine of unconditioned reflexes is associated with the research of I. M. Sechenov, E. Pfluger, F. Goltz, S. S. Sherrington, V. Magnus, N. E. Vvedensky, A. A. Ukhtomsky, who laid the foundations for the subsequent stage in the development of reflex theory, when it finally became possible to fill the concept of reflex arc, which existed before as an anatomical and physiological scheme (see Reflexes). The undoubted condition that determined the success of these quests was the full awareness that the nervous system acts as a single whole, and therefore acts as a very complex formation.

The brilliant foresights of I.M. Sechenov about the reflex basis of mental activity of the brain served as a starting point for research, which, developing the doctrine of higher nervous activity, discovered two forms of neuro-reflex activity: unconditioned and conditioned reflexes. Pavlov wrote: “... we must admit the existence of two types of reflex. One reflex is ready-made, with which the animal is born, a purely conductive reflex, and the other reflex is constantly, continuously formed during individual life, with exactly the same pattern, but based on another property of our nervous system - closure. One reflex can be called innate, the other - acquired, and also, accordingly: one - specific, the other - individual. We called the innate, specific, constant, stereotypical unconditional, the other, since it depends on many conditions, constantly fluctuates depending on many conditions, we called conditional...”

The complex dynamics of the interaction of conditioned reflexes (see) and unconditioned reflexes is the basis of the nervous activity of humans and animals. Biological significance unconditioned reflexes, as well as conditioned reflex activity, consists in adapting the body to various kinds of changes in the external and internal environment. Such important acts as self-regulation of functions are based on the adaptive activity of unconditioned reflexes. The precise adaptation of unconditioned reflexes to the qualitative and quantitative characteristics of the stimulus, especially carefully studied in Pavlov’s laboratories using examples of the work of the digestive glands, made it possible to interpret the problem of the biological expediency of unconditioned reflexes materialistically, bearing in mind the exact correspondence of the function to the nature of the irritation.

The differences between unconditioned and conditioned reflexes are not absolute, but relative. Various experiments, in particular with the destruction of various parts of the brain, allowed Pavlov to create a general idea of ​​​​the anatomical basis of conditioned and unconditioned reflexes: “Higher nervous activity,” wrote Pavlov, “is composed of the activity of the cerebral hemispheres and the nearest subcortical nodes, representing the combined activity of these two the most important departments central nervous system. These subcortical nodes are... centers of the most important unconditioned reflexes, or instincts: food, defensive, sexual, etc....". Pavlov’s stated views must now be recognized only as a diagram. His doctrine of analyzers (see) allows us to believe that the morphological substrate of unconditioned reflexes actually covers various parts of the brain, including the cerebral hemispheres, meaning the afferent representation of the analyzer from which this unconditioned reflex is evoked. In the mechanism of unconditioned reflexes, an important role belongs to feedback about the results and success of the action performed (P.K. Anokhin).

IN early years During the development of the doctrine of conditioned reflexes, individual students of Pavlov, who studied salivary unconditioned reflexes, asserted their extreme stability and immutability. Subsequent studies showed the one-sidedness of such views. In Pavlov's own laboratory, a number of experimental conditions were found under which unconditioned reflexes changed even during one experiment. Subsequently, facts were presented indicating that it is more correct to talk about the variability of unconditioned reflexes than about their immutability. Important points in this regard are: the interaction of reflexes with each other (both unconditioned reflexes with each other, and unconditioned reflexes with conditioned ones), hormonal-humoral factors of the body, the tone of the nervous system and its functional state. These questions acquire particular importance in connection with the problem of instincts (see), which a number of representatives of the so-called ethology (the science of behavior) try to present as unchanged, independent of the external environment. Sometimes it is difficult to determine specific factors of variability of unconditioned reflexes, especially if it concerns the internal environment of the body (hormonal, humoral or interoceptive factors), and then some scientists fall into the error of speaking about spontaneous variability of unconditioned reflexes. Such adeterministic constructions and idealistic conclusions lead away from the materialistic understanding of the reflex.

I. P. Pavlov repeatedly emphasized the importance of systematization and classification of unconditioned reflexes, which serve as the foundation for the rest of the nervous activity of the body. The existing stereotyped division of reflexes into food, self-preservation, and sexual ones is too general and inaccurate, he pointed out. A detailed systematization and careful description of all individual reflexes are necessary. Speaking about systematization along with classification, Pavlov meant the need for a broad study of individual reflexes or their groups. The task should be recognized as both very important and very difficult, especially since Pavlov did not distinguish such complex reflexes as instincts from the series of unconditioned reflex phenomena. From this point of view, it is especially important to study the already known and find new and complex shapes reflex activity. Here we must pay tribute to this logical direction, which in a number of cases obtains facts of undoubted interest. However, the ideological basis of this trend, which fundamentally denies reflex nature instincts.

An unconditioned reflex “in its pure form” can manifest itself one or several times after the birth of an animal, and then in a fairly short time it is “overgrown” with conditioned and other unconditioned reflexes. All this makes it very difficult to classify unconditioned reflexes. Until now, it has not been possible to find a single principle for their classification. For example, A.D. Slonim based his classification on the principle of balancing the organism with the external environment and maintaining a constant composition of its internal environment. In addition, he identified groups of reflexes that do not ensure the preservation of an individual, but are important for the preservation of the species. The classification of unconditioned reflexes and instincts proposed by N. A. Rozhansky is extensive. It is based on biological and environmental characteristics and the dual (positive and negative) manifestation of the reflex. Unfortunately, Rozhansky’s classification suffers from a subjective assessment of the essence of the reflex, which is reflected in the names of some reflexes.

Systematization and classification of unconditioned reflexes should provide for their ecological specialization. Given the ecological adequacy of the stimuli and the biological training of the effector, a very subtle differentiation of unconditioned reflexes appears. The speed, strength, and the very possibility of forming a conditioned reflex depend not so much on the physical or chemical characteristics of the stimulus, but on the ecological adequacy of the stimulus and the unconditioned reflex.

The problem of the emergence and development of unconditioned reflexes is of great interest. I. P. Pavlov, A. A. Ukhtomsky, K. M. Bykov, P. K. Anokhin and others believed that unconditioned reflexes arise as conditioned, and subsequently become fixed in evolution and become innate.

Pavlov pointed out that new emerging reflexes, while maintaining the same living conditions in a number of successive generations, apparently continuously transform into permanent ones. This is probably one of the operating mechanisms for the development of an animal organism. Without recognizing this position, it is impossible to imagine the evolution of nervous activity. Nature cannot allow such wastefulness, said Pavlov, that each new generation would have to start everything from the very beginning. Transitional forms of reflexes that occupied an intermediate position between conditioned and unconditioned were found with great biological adequacy of the stimuli (V.I. Klimova, V.V. Orlov, A.I. Oparin, etc.). These conditioned reflexes did not fade away. See also Higher nervous activity.

Human behavior is associated with conditioned-unconditioned reflex activity and represents higher nervous activity, the result of which is a change in the relationship of the organism with the external environment.

In contrast to higher nervous activity, lower nervous activity consists of a set of reactions aimed at unifying and integrating functions within the body.

Higher nervous activity manifests itself in the form of complex reflex reactions carried out with the obligatory participation of the cerebral cortex and the subcortical formations closest to it.

For the first time, the idea of ​​the reflex nature of brain activity was widely and in detail developed by the founder of Russian physiology I.M. Sechenov in his book “Reflexes of the Brain.” The ideological setting of this classic work is expressed in the original title, changed under the influence of censorship: “An attempt to introduce physiological basis into mental processes." Before I.M. Sechenov, physiologists and neurologists did not even dare to raise the question of the possibility of an objective, purely physiological analysis mental processes. The latter remained completely at the mercy of subjective psychology.

The ideas of I.M. Sechenov received brilliant development in the remarkable works of I.P. Pavlov, who opened the way for objective experimental research of the functions of the cerebral cortex and created a harmonious doctrine of higher nervous activity.

I. P. Pavlov showed that while in the underlying parts of the central nervous system - the subcortical nuclei, brain stem, spinal cord - reflex reactions are carried out along innate, hereditarily fixed nerve pathways, in the cerebral cortex nerve connections are developed and created in the process the individual life of animals and humans, as a result of a combination of countless irritations acting on the body.

The discovery of this fact made it possible to divide the entire set of reflex reactions occurring in the body into two main groups: unconditioned and conditioned reflexes.

Conditioned reflexes

• these are reactions acquired by the body in the process of individual development based on “life experience”
• are individual: some representatives of the same species may have them, while others may not
• unstable and depending on certain conditions they can develop, become established or disappear; this is their property and is reflected in their very name
• can be formed in response to a wide variety of stimuli applied to various receptive fields
• are closed at the level of the cortex. After removing the cerebral cortex, the developed conditioned reflexes disappear and only unconditioned ones remain.
• carried out through functional temporary connections

Conditioned reflexes are developed on the basis of unconditioned reflexes. For the formation of a conditioned reflex, it is necessary to combine the time of any change in the external environment and the internal state of the body, perceived by the cerebral cortex, with the implementation of one or another unconditioned reflex. Only under this condition does a change in the external environment or internal state of the body become a stimulus to a conditioned reflex - a conditioned stimulus, or signal. The irritation that causes an unconditioned reflex - unconditioned irritation - must, during the formation of a conditioned reflex, accompany the conditioned irritation and reinforce it.

For the formation of conditioned reflexes, it is necessary to create a temporary connection, a closure between the cortical cells that perceive conditioned stimulation and the cortical neurons that are part of the unconditioned reflex arc.

When conditioned and unconditioned stimulation coincide and combine, a connection is established between different neurons in the cerebral cortex and a process of closure occurs between them.

Unconditioned reflexes

• These are innate, hereditary reactions of the body
• are specific, i.e. characteristic of all representatives of a given species
• relatively constant, as a rule, persist throughout life
• carried out in response to adequate stimulation applied to one specific receptive field
• closes at the level of the spinal cord and brainstem
• are carried out through a phylogenetically fixed, anatomically expressed reflex arc.

It should be noted, however, that in humans and monkeys, who have a high degree of corticalization of functions, many complex unconditioned reflexes are carried out with the obligatory participation of the cerebral cortex. This is proven by the fact that its lesions in primates lead to pathological disorders of unconditioned reflexes and the disappearance of some of them.

It should also be emphasized that not all unconditioned reflexes appear immediately at the time of birth. Many unconditioned reflexes, for example, those associated with locomotion and sexual intercourse, arise in humans and animals a long time after birth, but they necessarily appear under the condition of normal development of the nervous system.

The entire set of unconditioned and conditioned reflexes formed on their basis is usually divided into a number of groups according to their functional significance.

1. By receptor
   1. Exteroceptive reflexes
      • visual
      • olfactory
      • flavoring, etc.
   2. Interoreceptive reflexes- reflexes in which the conditioned stimulus is irritation of the receptors of internal organs by a change chemical composition, temperature of internal organs, pressure in hollow organs and vessels
2. By effector trait, i.e. by those effectors that respond to stimulation
   1. autonomic reflexes
      • food
      • cardiovascular
      • respiratory, etc.
   2. somato-motor reflexes- manifested in movements of the whole organism or its individual parts in response to a stimulus
      • defensive
3. According to biological significance
   1. Food
      • reflex act of swallowing
      • reflexive act of chewing
      • reflex act of sucking
      • reflex act of salivation
      • reflex act of secretion of gastric and pancreatic juice, etc.
   2. Defensive- reactions to eliminate damaging and painful stimuli
   3. Genital- reflexes associated with sexual intercourse; This group also includes the so-called parental reflexes associated with feeding and nursing the offspring.
   4. Stato-kinetic and locomotor- reflex reactions of maintaining a certain position and movement of the body in space.
   5. Reflexes for maintaining homeostasis
      • thermoregulation reflex
      • breathing reflex
      • cardiac reflex
      • vascular reflexes that help maintain constant blood pressure, etc.
   6. Orienting reflex- reflex to novelty. It occurs in response to any fairly quickly occurring fluctuation in the environment and is expressed externally in alertness, listening to a new sound, sniffing, turning the eyes and head, and sometimes the whole body towards the emerging light stimulus, etc. The implementation of this reflex provides better perception of the acting agent and has important adaptive significance.

      I. P. Pavlov figuratively called the indicative reaction the “what is it?” reflex. This reaction is innate and does not disappear when complete removal cerebral cortex in animals; it is also observed in children with underdeveloped cerebral hemispheres - anencephals.

The difference between the orienting reflex and other unconditioned reflex reactions is that it fades away relatively quickly with repeated applications of the same stimulus. This feature of the orientation reflex depends on the influence of the cerebral cortex on it.

The above classification of reflex reactions is very close to the classification of various instincts, which are also divided into food, sexual, parental, and defensive. This is understandable due to the fact that, according to I.P. Pavlov, instincts are complex unconditioned reflexes. Their distinctive features is the chain nature of the reactions (the end of one reflex serves as the trigger for the next) and their dependence on hormonal and metabolic factors. Thus, the emergence of sexual and parental instincts is associated with cyclical changes in the functioning of the gonads, and the food instinct depends on those metabolic changes that develop in the absence of food. One of the features of instinctive reactions is also that they are characterized by many properties of the dominant.

The reflex component is a reaction to irritation (movement, secretion, change in breathing, etc.).

Most unconditioned reflexes are complex reactions that include several components. So, for example, with an unconditioned defensive reflex, caused in a dog by strong electrocutaneous irritation of the limb, along with defensive movements, breathing also increases and increases, cardiac activity accelerates, vocal reactions appear (squealing, barking), the blood system changes (leukocytosis, platelets and etc.). The food reflex also distinguishes between its motor (grasping food, chewing, swallowing), secretory, respiratory, cardiovascular and other components.

Conditioned reflexes, as a rule, reproduce the structure of the unconditioned reflex, since the conditioned stimulus excites the same nerve centers as the unconditioned one. Therefore, the composition of the components of the conditioned reflex is similar to the composition of the components of the unconditioned reaction.

Among the components of a conditioned reflex, there are main, specific for a given type of reflex, and secondary components. In the defensive reflex the main component is the motor component, in the food reflex the main component is the motor and secretory ones.

Changes in respiration, cardiac activity, and vascular tone that accompany the main components are also important for the animal’s holistic response to a stimulus, but they play, as I. P. Pavlov said, “a purely auxiliary role.” Thus, increased and increased respiration, increased heart rate, increased vascular tone, caused by a conditioned defensive stimulus, contribute to increased metabolic processes in skeletal muscles and thereby create optimal conditions for the implementation of protective motor reactions.

When studying conditioned reflexes, the experimenter often chooses one of its main components as an indicator. That is why they talk about conditioned and unconditioned motor or secretory or vasomotor reflexes. It is necessary, however, to take into account that they represent only individual components of the body’s holistic reaction.

The biological significance of conditioned reflexes is that they make it possible to adapt much better and more accurately to the conditions of existence and to survive in these conditions.

As a result of the formation of conditioned reflexes, the body reacts not only directly to unconditioned stimuli, but also to the possibility of their action on it; reactions appear some time before unconditional irritation. In this way, the body is prepared in advance for the actions that it has to carry out in a given situation. Conditioned reflexes contribute to finding food, avoiding danger in advance, eliminating harmful influences, etc.

The adaptive significance of conditioned reflexes is also manifested in the fact that the precedence of conditioned stimulation by an unconditioned one strengthens the unconditioned reflex and accelerates its development.

Animal behavior is different shapes external, predominantly motor activity aimed at establishing vital connections between the body and the environment. Animal behavior consists of conditioned, unconditioned reflexes and instincts. Instincts include complex unconditioned reactions, which, being innate, appear only during certain periods of life (for example, the instinct of nesting or feeding offspring). Instincts play a leading role in the behavior of lower animals. However, the higher an animal is at the evolutionary level, the more complex and varied its behavior, the more perfect and subtle it adapts to environment and the greater the role that conditioned reflexes play in his behavior.

The environment in which animals exist is very variable. Adaptation to the conditions of this environment through conditioned reflexes will be subtle and accurate only if these reflexes are also changeable, that is, conditioned reflexes unnecessary in the new environmental conditions will disappear, and new ones will form in their place. The disappearance of conditioned reflexes occurs due to inhibition processes.

A distinction is made between external (unconditioned) inhibition of conditioned reflexes and internal (conditioned) inhibition.

External inhibition of conditioned reflexes occurs under the influence of extraneous stimuli that cause a new reflex reaction. This inhibition is called external because it develops as a result of processes occurring in areas of the cortex that are not involved in the implementation of this conditioned reflex.

Extremely strong or long-acting extraneous stimuli can cause extreme inhibition of reflexes.

Internal inhibition of conditioned reflexes occurs in the absence of reinforcement by an unconditioned stimulus of the received signal.

Internal inhibition does not occur immediately. As a rule, repeated use of a non-reinforced signal is required.

The fact that this is inhibition of the conditioned reflex, and not its destruction, is evidenced by the restoration of the reflex the next day, when the inhibition has passed. Various diseases, overwork, and overstrain cause a weakening of internal inhibition.

If a conditioned reflex is extinguished (not reinforced with food) for several days in a row, it may disappear completely.

There are several types of internal inhibition. The form of inhibition discussed above is called extinction inhibition. This inhibition underlies the disappearance of unnecessary conditioned reflexes.

Another type is differentiated (discriminating) inhibition.

A non-reinforced conditioned stimulus causes inhibition in the cortex and is called an inhibitory stimulus. Using the described technique, it was possible to determine the discriminative ability of different sense organs in animals.

The phenomenon of disinhibition. It is known that extraneous stimuli cause inhibition of conditioned reflexes. If an extraneous stimulus occurs during the action of an inhibitory stimulus, for example, during the action of a metronome at a frequency of 100 times per minute, as in the previous case, then this will cause the opposite reaction - saliva will flow. I.P. Pavlov called this phenomenon disinhibition and explained it by the fact that an extraneous stimulus, causing an orienting reflex, inhibits any other process that occurs in this moment in the centers of the conditioned reflex. If the inhibition process is inhibited, then all this leads to excitation and implementation of the conditioned reflex.

The phenomenon of disinhibition also indicates the inhibitory nature of the processes of discrimination and extinction of conditioned reflexes.

The meaning of conditional inhibition very large. Thanks to inhibition, a significantly better matching of the body's reaction is achieved external conditions, more perfectly adapting it to the environment. The combination of two forms of a single nervous process - excitation and inhibition - and their interaction make it possible for the body to navigate in different difficult situations, are the conditions for the analysis and synthesis of stimuli.