Where unconditioned reflexes close. Reflex - example

A reflex is the body's response to an internal or external stimulus, carried out and controlled by the central nervous system. Our compatriots I.P. Pavlov and I.M. Sechenov.

What are unconditioned reflexes?

An unconditioned reflex is an innate stereotyped reaction of the body to the influence of the internal or environment, inherited from the offspring from the parents. It remains with a person throughout his life. Reflex arcs pass through the brain and the cerebral cortex does not take part in their formation. The significance of the unconditioned reflex is that it ensures the adaptation of the human body directly to those changes in the environment that often accompanied many generations of his ancestors.

What reflexes are unconditioned?

The unconditioned reflex is the main form of activity of the nervous system, an automatic response to a stimulus. And since various factors affect a person, then the reflexes are different: food, defensive, indicative, sexual ... Salivation, swallowing and sucking are food. Defensive are coughing, blinking, sneezing, withdrawal of limbs from hot objects. Orienting reactions can be called turns of the head, squinting of the eyes. Sexual instincts include reproduction, as well as caring for offspring. The value of the unconditioned reflex lies in the fact that it ensures the preservation of the integrity of the body, maintains the constancy of the internal environment. Thanks to him, reproduction occurs. Even in newborns, an elementary unconditioned reflex can be observed - this is sucking. By the way, it is the most important. The irritant in this case is the touch to the lips of an object (nipples, mother's breasts, toys or fingers). Another important unconditioned reflex is blinking, which occurs when a foreign body approaches the eye or touches the cornea. This reaction refers to the protective or defensive group. It is also observed in children, for example, when exposed to strong light. However, the signs of unconditioned reflexes are most pronounced in various animals.

What are conditioned reflexes?

Reflexes acquired by the body during life are called conditioned reflexes. They are formed on the basis of inherited ones, subject to the influence of an external stimulus (time, knock, light, and so on). A vivid example is the experiments carried out on dogs by Academician I.P. Pavlov. He studied the formation of this type of reflexes in animals and was the developer of a unique technique for obtaining them. So, to develop such reactions, it is necessary to have a regular stimulus - a signal. It starts the mechanism, and repeated repetition of the stimulus effect allows you to develop. In this case, a so-called temporary connection arises between the arcs of the unconditioned reflex and the centers of the analyzers. Now the basic instinct is awakening under the action of fundamentally new signals of an external nature. These stimuli of the surrounding world, to which the organism was previously indifferent, begin to acquire an exceptional, vital importance. Each living being can develop many different conditioned reflexes during his life, which form the basis of his experience. However, this applies only to this particular individual, by inheritance this life experience will not be transmitted.

An independent category of conditioned reflexes

In an independent category, it is customary to single out conditioned reflexes of a motor nature developed during life, that is, skills or automated actions. Their meaning lies in the development of new skills, as well as the development of new motor forms. For example, over the entire period of his life, a person masters many special motor skills that are associated with his profession. They are the basis of our behavior. Thinking, attention, consciousness are freed when performing operations that have reached automatism and become a reality. Everyday life. The most successful way of mastering the skills is the systematic implementation of the exercise, the timely correction of the noticed mistakes, as well as the knowledge of the ultimate goal of any task. In the event that the conditioned stimulus is not reinforced for some time by the unconditioned stimulus, its inhibition occurs. However, it does not completely disappear. If, after some time, the action is repeated, the reflex will quickly recover. Inhibition can also occur under the condition of the appearance of an irritant of even greater force.

Compare unconditioned and conditioned reflexes

As mentioned above, these reactions differ in the nature of their occurrence and have a different formation mechanism. In order to understand what the difference is, just compare unconditioned and conditioned reflexes. So, the first are present in a living being from birth, during the whole life they do not change and do not disappear. In addition, unconditioned reflexes are the same in all organisms of a particular species. Their meaning is to prepare the living being for constant conditions. The reflex arc of such a reaction passes through the brain stem or spinal cord. As an example, here are some (congenital): active salivation when a lemon enters the mouth; sucking movement of the newborn; coughing, sneezing, pulling hands away from a hot object. Now consider the characteristics of conditioned reactions. They are acquired throughout life, can change or disappear, and, no less important, they are individual (their own) for each organism. Their main function is the adaptation of a living being to changing conditions. Their temporary connection (centers of reflexes) is created in the cerebral cortex. An example of a conditioned reflex is the reaction of an animal to a nickname, or the reaction of a six-month-old child to a bottle of milk.

Scheme of the unconditioned reflex

According to the research of academician I.P. Pavlova, general scheme unconditioned reflexes is as follows. Certain receptor nervous devices are affected by certain stimuli of the internal or external world of the organism. As a result, the resulting irritation transforms the entire process into the so-called phenomenon of nervous excitation. It is transmitted through nerve fibers (as through wires) to the central nervous system, and from there it goes to a specific working organ, already turning into a specific process at the cellular level of this part of the body. It turns out that these or those irritants are naturally connected with this or that activity in the same way as the cause with the effect.

Features of unconditioned reflexes

The characteristic of unconditioned reflexes presented below, as it were, systematizes the material presented above, it will help to finally understand the phenomenon we are considering. So, what are the features of inherited reactions?

Unconditional instinct and animal reflex

The exceptional constancy of the nervous connection underlying the unconditional instinct is explained by the fact that all animals are born with a nervous system. She is already able to respond properly to specific environmental stimuli. For example, a creature might flinch at a harsh sound; he will secrete digestive juice and saliva when food enters the mouth or stomach; it will blink with visual stimulation, and so on. Innate in animals and humans are not only individual unconditioned reflexes, but also much more complex forms of reactions. They are called instincts.

The unconditioned reflex, in fact, is not a completely monotonous, stereotyped, transfer reaction of an animal to an external stimulus. It is characterized, though elementary, primitive, but still by variability, variability, depending on external conditions (strength, peculiarities of the situation, position of the stimulus). In addition, it is also influenced by the internal states of the animal (reduced or increased activity, posture, and others). So, even I.M. Sechenov in his experiments with decapitated (spinal) frogs showed that when the toes of the hind legs of this amphibian are acted upon, the opposite motor reaction occurs. From this we can conclude that the unconditioned reflex still has adaptive variability, but within insignificant limits. As a result, we find that the balancing of the organism and the external environment achieved with the help of these reactions can be relatively perfect only in relation to slightly changing factors of the surrounding world. The unconditioned reflex is not able to ensure the adaptation of the animal to new or dramatically changing conditions.

As for the instincts, sometimes they are expressed in the form of simple actions. For example, a rider, thanks to his sense of smell, looks for the larvae of another insect under the bark. He pierces the bark and lays his egg in the found victim. This is the end of all its action, which ensures the continuation of the genus. There are also complex unconditioned reflexes. Instincts of this kind consist of a chain of actions, the totality of which ensures the continuation of the species. Examples include birds, ants, bees and other animals.

Species specificity

Unconditioned reflexes(species) are present in both humans and animals. It should be understood that such reactions in all representatives of the same species will be the same. An example is a turtle. All species of these amphibians retract their heads and limbs into their shells when threatened. And all the hedgehogs jump up and make a hissing sound. In addition, you should be aware that not all unconditioned reflexes occur at the same time. These reactions change according to age and season. For example, the breeding season or the motor and sucking actions that appear in an 18-week-old fetus. Thus, unconditioned reactions are a kind of development for conditioned reflexes in humans and animals. For example, in young children, as they grow older, there is a transition to the category of synthetic complexes. They increase the adaptability of the body to external environmental conditions.

Unconditional braking

In the process of life, each organism is regularly exposed - both from the outside and from the inside - to various stimuli. Each of them is able to cause a corresponding reaction - a reflex. If all of them could be realized, then the vital activity of such an organism would become chaotic. However, this does not happen. On the contrary, reactionary activity is characterized by consistency and orderliness. This is explained by the fact that inhibition of unconditioned reflexes occurs in the body. This means that the most important reflex at a particular moment of time delays the secondary ones. Usually, external inhibition can occur at the time of the start of another activity. The new exciter, being stronger, leads to the attenuation of the old one. And as a result, the previous activity will automatically stop. For example, a dog is eating and at that moment the doorbell rings. The animal immediately stops eating and runs to meet the visitor. There is an abrupt change in activity, and the dog's salivation stops at that moment. Certain innate reactions are also referred to as unconditional inhibition of reflexes. In them, certain pathogens cause a complete cessation of some actions. For example, the anxious clucking of a chicken causes the chickens to freeze and cling to the ground, and the onset of darkness forces the kenar to stop singing.

In addition, there is also a protective id that arises as a response to a very strong stimulus that requires actions from the body that exceed its capabilities. The level of such exposure is determined by the frequency of impulses of the nervous system. The stronger the neuron is excited, the higher the frequency of the flow of nerve impulses that it generates will be. However, if this flow exceeds certain limits, then a process will occur that will begin to prevent the passage of excitation through the neural circuit. The flow of impulses along the reflex arc of the spinal cord and brain is interrupted, as a result, inhibition occurs, which preserves the executive organs from complete exhaustion. What follows from this? Thanks to the inhibition of unconditioned reflexes, the body secretes from all options the most adequate, capable of protecting against unbearable activities. This process also contributes to the manifestation of the so-called biological caution.

Each person, as well as all living organisms, has a number of vital needs: food, water, comfortable conditions. Everyone has the 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. That's what it is congenital reflexes that help you survive.

The concept of an unconditioned reflex

The very word reflex for each of us is not something new and unfamiliar. Everyone has heard it in their life, and enough times. This term was introduced into biology by IP Pavlov, who devoted much time to the study of the nervous system.

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

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

We live in a changing environment, it requires constant adaptations that cannot be foreseen by genetic experience. The unconditioned reflexes of a person are constantly inhibited, then modified or reappeared, 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 characteristic of unconditioned reflexes includes several mandatory points:

1. Congenital reflexes are inherited.
2. They are the same in all individuals of this species.
3. For a response to occur, the influence of a certain factor is necessary, for example, for a sucking reflex, this is irritation of the lips of a newborn.
4. The zone 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 on the level of reflex responses. Unconditioned and conditioned reflexes play an important role in the existence of the organism.

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

Congenital reflexes begin to appear already in utero, and their role is as follows:

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

The role of innate reactions immediately after birth is great; it is they that ensure the survival of the infant in completely new conditions for him.

The body lives in an environment of external factors that are constantly changing, and it is necessary to adapt to them. This is where higher nervous activity comes to the fore in the form of conditioned reflexes.

For the body, they have the following meaning:

• Improve the mechanisms of its interaction with the environment.
• They clarify and complicate the processes of contacting the body with the external environment.
• 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

The hereditary reactions of the body, despite their innate nature, can be very different 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 attributed the sucking reflex to them).
• Difficult (sweating).
• The most complex unconditioned reflexes. Examples can be given in a variety of ways: food reactions, defensive, sexual.

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 features:

1. If they are not satisfied, then this will lead to the death of the body.
2. For satisfaction, there is no need for the presence of another individual of the same species.

The third group also has its own characteristic features:

1. Reflexes of self-development are in no way connected with the adaptation of the organism to a given situation. They are directed towards the future.
2. They are completely independent and do not follow from other needs.

You can also divide by the level of their complexity, then the following groups will appear before us:

1. simple reflexes. These are the body's normal responses to external stimuli. For example, pulling your hand away from a hot object or blinking when a mote 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 activity of the organism, therefore they are always reliable in their manifestation and cannot be corrected.

These include:

• Breath.
• swallowing.
• Vomit.

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

Behavior reactions

This variety of unconditioned reflexes can be well demonstrated in animals. Behavioral responses include:

• The desire of the dog to carry and pick up objects. Aportation reaction.
• Showing aggression at the sight stranger. Active defensive reaction.
• Search for items by smell. Olfactory-search reaction.

It is worth noting that the reaction of behavior does not yet 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 actions of the animal, but it is quite possible to control them. They should also be taken into account when training: if an animal has no olfactory-search reaction at all, then it is unlikely that it will be possible to raise a search dog out of it.

instincts

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

All instincts are connected with changing inner needs.

When a baby 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 action on the respiratory center, and an instinctive inhalation takes place. 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 for success in a certain field of activity. When we cease to control ourselves, then instincts begin to lead us. As you can imagine, there are several of them.

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

1. Self-preservation and survival.
2. Procreation.
3. Leader instinct.

All of them can give rise to new needs:

• In safety.
• In material abundance.
• Looking for a sexual partner.
• In caring for children.
• Influencing others.

You can still list the varieties of human instincts for a long time, but, unlike animals, we can control them. To do this, nature has endowed us with reason. Animals survive only due to instincts, but we are also given knowledge for this.

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

imprinting

This form of unconditioned reflex is also called imprinting. In the life of every individual there are periods when the whole environment is imprinted in the brain. For each species, this time period can be different: for some it lasts several hours, and for some it can take several years.

Remember how easy it is for young children to master the skills of foreign speech. While students put a lot of effort into this.

It is thanks to imprinting that all babies recognize their parents, distinguish individuals of their own species. For example, a zebra, after the birth of a cub, is alone with him for several hours in a secluded place. This is just the time it takes 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. Even they perceived him as a mother, and pursued him on his heels.

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

Congenital reflexes of an infant

After his birth, the baby goes through a complex path of development, which consists of several stages. The degree and speed of mastering various skills will directly depend on the state of the nervous system. The main indicator of its maturity are the unconditioned reflexes of the newborn.

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

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

1. Kussmaul's search reflex. When the area around the mouth is irritated, the child turns the head towards the irritant. Usually the reflex fades by 3 months.
2. Sucking. If you put your finger in the baby's mouth, then he begins to perform sucking movements. Immediately after feeding, this reflex fades away and is activated after a while.
3. Palmar-oral. If the child presses on the palm, then he opens his mouth.
4. Grasping reflex. If you put your finger in the palm of the baby and lightly press it, then there is a reflex squeezing and holding it.
5. The lower grasp reflex is elicited by light pressure on the front of the sole. There is flexion of the toes.
6. crawling reflex. In the prone position, pressure on the soles of the feet causes a forward crawling motion.
7. Protective. If you put the newborn on his stomach, he tries to raise his head and turns it to the side.
8. Support reflex. If you take the baby under the armpits and put it on something, then it reflexively unbends the legs and rests on the whole foot.

The unconditioned reflexes of a newborn can be listed for a long time. Each of them symbolizes the degree of development of certain parts of the nervous system. Already after examination by a neurologist in the maternity hospital, it is possible to make a preliminary diagnosis of some diseases.

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 muscle tone. The centers are located in the middle and medulla oblongata.

Oral segmental reflexes

These types of reflexes include:

• Sucking. It appears during the first year of life.
• Search. Fading occurs at 3-4 months.
• Proboscis reflex. If you hit the baby with a finger on the lips, then he pulls them into the proboscis. After 3 months, fading occurs.
• The palmar-mouth reflex well shows the development of the nervous system. If it does not manifest itself or is very weak, then we can talk about the defeat of the central nervous system.

Spinal motor automatisms

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

• Moro reflex. When a reaction is evoked, for example, by hitting the table not far from the baby's head, the latter's arms are spread to the sides. Appears up to 4-5 months.
• Automatic gait reflex. With support and a slight tilt forward, the baby makes stepping movements. After 1.5 months it starts to fade.
• Reflex Galant. If you run your finger along the paravertebral line from the shoulder to the buttocks, then the torso flexes towards the stimulus.

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

Differences between conditioned and unconditioned reflexes

Sechenov also argued that under the conditions in which the organism lives, it is completely insufficient for the survival of innate reactions, the development of new reflexes is required. They will contribute to the adaptation of the body to changing conditions.

How do unconditioned reflexes differ from conditioned ones? The table shows 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 REFLEX (species, natural reflex) - a constant and innate reaction of the body to certain influences of the external world, carried out with the help of the nervous system and does not require special conditions for its occurrence. The term was introduced by IP Pavlov in the study of the physiology of higher nervous activity. An unconditioned reflex occurs unconditionally if adequate stimulation is applied to a certain receptor surface. In contrast to this unconditionally emerging reflex, IP Pavlov discovered the category of reflexes, for the formation of which a number of conditions must be met - a conditioned reflex (see).

The physiological feature of the unconditioned reflex is its relative constancy. An unconditioned reflex always occurs with the corresponding external or internal stimuli, manifesting itself on the basis of innate neural connections. Since the constancy of the corresponding unconditioned reflex is the result of the phylogenetic development of a given animal species, this reflex received the additional name "species reflex".

The biological and physiological role of the unconditioned reflex is that, thanks to this innate reaction, animals of a given species adapt (in the form of expedient acts of behavior) to the constant factors of existence.

The division of reflexes into two categories - unconditioned and conditioned - corresponds to two forms of the nervous activity of animals and humans, which were clearly distinguished by IP Pavlov. The totality of the unconditioned reflex is the lower nervous activity, while the totality of acquired, or conditioned, reflexes is the higher nervous activity (see).

It follows from this definition that the unconditioned reflex, in terms of its physiological significance, along with the implementation of constant adaptive reactions of the animal in relation to the action of environmental factors, also determines those interactions nervous processes, which together direct the internal life of the organism. IP Pavlov attached particular importance to this last property of the unconditioned reflex. Thanks to the innate neural connections that ensure the interaction of organs and processes within the body, the animal and the person acquire an accurate and stable course of basic vital functions. The principle on the basis of which these interactions and the integration of activities within the body are organized is the self-regulation of physiological functions (see).

The classification of unconditioned reflexes can be built on the basis of the specific properties of the acting stimulus and the biological meaning of the responses. It was on this principle that the classification was built in the laboratory of IP Pavlov. In accordance with this, there are several types of unconditioned reflex:

1. Food, the causative agent of which is the action of food substances on the receptors of the tongue and on the basis of the study of which all the basic laws of higher nervous activity are formulated. Due to the spread of excitation from the receptors of the tongue towards the central nervous system, the branched congenital nervous structures that generally make up the food center are excited; as a result of such a fixed relationship between the central nervous system and the working peripheral apparatuses, responses of the whole organism are formed in the form of an unconditioned food reflex.

2. Defensive, or, as it is sometimes called, protective reflex. This unconditioned reflex has a number of forms, depending on which organ or part of the body is in danger. So, for example, the application of pain irritation to a limb causes a withdrawal of the limb, which protects it from further destructive action.

In a laboratory setting, as an irritant that causes a defensive unconditioned reflex, they usually use electric current from the corresponding devices (Dubois-Reymond induction coil, city current with a corresponding voltage drop, etc.). If air movement directed at the cornea of ​​the eye is used as an irritant, then the defensive reflex is manifested by the closing of the eyelids - the so-called blinking reflex. If the irritants are potent gaseous substances that are passed through the upper respiratory tract, then the delay in respiratory excursions of the chest will be a protective reflex. The most commonly used in the laboratory of IP Pavlov is a kind of protective reflex - an acid protective reflex. It is expressed by a strong rejection reaction (vomiting) in response to an infusion of a solution of hydrochloric acid into the animal's mouth.

3. Sexual, which certainly arises in the form of sexual behavior in response to an adequate sexual stimulus in the form of an individual of the opposite sex.

4. Approximate-exploratory, which is manifested by a rapid movement of the head towards the external stimulus that has acted at the moment. The biological meaning of this reflex consists in a detailed examination of the acting stimulus and, in general, of the external environment in which this stimulus arose. Due to the presence of innate pathways of this reflex in the central nervous system, the animal is able to expediently respond to sudden changes in outside world(see Approximate-exploratory reaction).

5. Reflexes from internal organs, reflexes during irritation of muscles, tendons (see Visceral reflexes, Tendon reflexes).

A common property of all unconditioned reflexes is that they can serve as the basis for the formation of acquired, or conditioned, reflexes. Some of the unconditioned reflexes, for example, defensive ones, lead to the formation of conditioned reactions very quickly, often after one combination of some external stimulus with pain reinforcement. The ability of other unconditioned reflexes, such as blinking or knee, to form temporary connections with an indifferent external stimulus is less pronounced.

It should also be taken into account that the rate of development of conditioned reflexes is directly dependent on the strength of the unconditioned stimulus.

The specificity of unconditioned reflexes lies in the exact correspondence of the body's response to the nature of the stimulus acting on the receptor apparatus. So, for example, when the taste buds of the tongue are irritated by a certain food, the reaction of the salivary glands in terms of the quality of the discharged secret is in exact accordance with the physical and chemical properties of the food taken. If the food is dry, then watery saliva is separated, but if the food is sufficiently moistened, but consists of pieces (for example, bread), the unconditioned salivary reflex will manifest itself in accordance with this food quality: saliva will contain a large amount of mucous glucoprotein - mucin, which prevents injury to food ways.

A fine receptor assessment is associated with a lack of one or another substance in the blood, for example, the so-called calcium starvation in children during the period of bone formation. Since calcium selectively passes through the capillaries of the developing bones, eventually its amount becomes below the constant. This factor is a selective stimulus of some specific cells of the hypothalamus, which in turn keeps the tongue receptors in a state of increased excitability. This is how the desire for children to eat plaster, whitewash and other mineral substances containing calcium is formed.

Such an expedient correspondence of the unconditioned reflex to the quality and strength of the acting stimulus depends on the extremely differentiated action of food substances and their combinations on the receptors of the tongue. Receiving these combinations of afferent excitations from the periphery, the central apparatus of the unconditioned reflex sends efferent excitations to the peripheral apparatuses (glands, muscles), leading to the formation of a certain composition of saliva or the appearance of movements. Indeed, the composition of saliva can be easily changed through a relative change in the production of its main ingredients: water, proteins, salts. From this it follows that the central apparatus of salivation can vary the quantity and quality of the excited elements depending on the quality of the excitation that came from the periphery. The correspondence of the unconditioned response to the specificity of the applied stimulus can go quite far. IP Pavlov developed the concept of the so-called digestive warehouse of certain unconditioned reactions. For example, if an animal is fed a certain type of food for a long time, then the digestive juices of its glands (gastric, pancreatic, etc.) eventually acquire a certain composition in terms of the amount of water, inorganic salts, and especially the activity of enzymes. Such a "digestive warehouse" cannot but be recognized as an expedient adaptation of innate reflexes to the established constancy of food reinforcement.

At the same time, these examples show that the stability, or immutability, of the unconditioned reflex is only relative. There is reason to believe that already in the first days after birth, the specific "tuning" of the language receptors is prepared by the embryonic development of animals, which ensures the successful selection of nutrients and the planned course of unconditioned reactions. So, if the percentage of sodium chloride content in the mother's milk, which a newborn child eats, is increased, then the child's sucking movements are immediately inhibited, and in some cases the child actively throws out the already taken mixture. This example convinces us that the innate properties of food receptors, as well as the properties of intranervous relationships, most accurately reflect the needs of the newborn.

Methodology for applying unconditioned reflexes

Since in the practice of work on higher nervous activity the unconditioned reflex is a reinforcing factor and the basis for the development of acquired, or conditioned, reflexes, the question of methodological methods for using the unconditioned reflex becomes especially important. In experiments on conditioned reflexes, the use of the alimentary unconditioned reflex is based on feeding the animal certain food substances from an automatically supplied feeder. With this method of using the unconditioned stimulus, the direct action of food on the receptors of the animal's tongue is inevitably preceded by a number of side irritations of the receptors related to various analyzers (see).

No matter how technically perfect the presentation of the feeder, it will certainly produce some kind of noise or knock and, therefore, this sound stimulus is the inevitable precursor of the truest unconditioned stimulus, that is, the stimulus of the taste buds of the tongue. To eliminate these defects, a method was developed for the direct introduction of nutrients into the oral cavity, while irrigation of the taste buds of the tongue, for example, with a sugar solution, is a direct unconditioned stimulus, not complicated by any side agent.

It should be noted, however, that under natural conditions, animals and humans never receive food into the oral cavity without preliminary sensations (the sight, the smell of food, etc.). Therefore, the method of direct introduction of food into the mouth has some abnormal conditions and the reaction of the animal to the unusualness of such a procedure.

In addition to this use of an unconditioned stimulus, there are a number of methods in which the animal itself receives food with the help of special movements. These include a wide variety of devices with the help of which an animal (rat, dog, monkey), by pressing the appropriate lever or button, receives food - the so-called instrumental reflexes.

The methodological features of reinforcement with an unconditioned stimulus have an undoubted influence on the experimental results obtained, and, therefore, the evaluation of the results should be made taking into account the type of unconditioned reflex. This is especially true for the comparative evaluation of the alimentary and defensive unconditioned reflexes.

While reinforcement with a food unconditioned stimulus is a positive factor for an animal biological significance(IP Pavlov), on the contrary, reinforcement with a painful stimulus is a stimulus for a biologically negative unconditioned reaction. It follows from this that "non-reinforcement" of a well-hardened conditioned reflex by an unconditioned stimulus in either case will have an opposite biological sign. While non-reinforcement of the conditioned stimulus with food leads to a negative and often aggressive reaction in the experimental animal, on the contrary, non-reinforcement of the conditioned signal with an electric current leads to a completely distinct biological positive reaction. These features of the animal's attitude to the non-reinforcement of the conditioned reflex by one or another unconditioned stimulus can be well revealed by such a vegetative component as respiration.

Composition and localization of unconditioned reflexes

The development of experimental techniques made it possible to study the physiological composition and localization of the unconditioned alimentary reflex in the central nervous system. For this purpose, the very action of the unconditioned food stimulus on the receptors of the tongue was studied. An unconditioned stimulus, regardless of its nutritional properties and consistency, primarily irritates the tactile receptors of the tongue. This is the fastest type of excitation, which is part of the unconditioned irritation. Tactile receptors produce the fastest and highest-amplitude type of nerve impulses, which are the first to propagate along the lingual nerve to the medulla oblongata and only after a few fractions of a second (0.3 seconds) do nerve impulses from temperature and chemical irritation of the tongue receptors arrive there. This feature of the unconditioned stimulus, which manifests itself in the successive excitation of various receptors of the tongue, is of great physiological importance: in the central nervous system, conditions are created for signaling each previous stream of impulses about subsequent stimuli. Owing to such correlations and characteristics of tactile excitation, which depend on the mechanical properties of the given food, in response to these excitations alone, salivation can occur before the chemical properties of the food act.

Special experiments carried out on dogs and a study of the behavior of newborns have shown that such correlations between individual parameters of the unconditioned stimulus are used in the adaptive behavior of the newborn.

So, for example, in the first days after birth, the chemical qualities of the child's food intake are the decisive stimulus. However, after a few weeks, the leading role passes to the mechanical properties of food.

In the life of adults, information about the tactile parameters of food is faster than information about chemical parameters in the brain. Due to this pattern, the sensation of “porridge”, “sugar”, etc. is born before the chemical signal arrives in the brain. According to the teachings of IP Pavlov about the cortical representation of the unconditioned reflex, each unconditioned irritation, along with the inclusion of subcortical apparatuses, has its own representation in the cerebral cortex. Based on the above data, as well as oscillographic and electroencephalographic analysis of the distribution of unconditioned excitation, it was found that it does not have a single point or focus in the cerebral cortex. Each of the fragments of unconditioned excitation (tactile, temperature, chemical) is addressed to different points of the cerebral cortex, and only almost simultaneous excitation of these points of the cerebral cortex establishes a systemic connection between them. These new data correspond to IP Pavlov's ideas about the structure of the nerve center, but require a change in existing ideas about the "cortical point" of the unconditioned stimulus.

Studies of cortical processes using electrical appliances showed that the unconditioned stimulus comes to the cerebral cortex in the form of a very generalized stream of ascending excitations, and, obviously, to each cell of the cortex. This means that not a single excitation of the sense organs that preceded the unconditioned stimulus can "escape" its convergence with the unconditioned excitation. These properties of the unconditioned stimulus reinforce the idea of ​​the "convergent closure" of the conditioned reflex.

Cortical representations of unconditioned reactions are such cellular complexes that take an active part in the formation of a conditioned reflex, that is, in the closing functions of the cerebral cortex. By its nature, the cortical representation of the unconditioned reflex must have an afferent character. As you know, I. P. Pavlov considered the cerebral cortex "an isolated afferent section of the central nervous system."

Complex unconditioned reflexes. I. P. Pavlov singled out a special category of the unconditioned reflex, in which he included innate activities that have a cyclic and behavioral character - emotions, instincts and other manifestations of complex acts of innate activity of animals and humans.

According to the initial opinion of IP Pavlov, complex unconditioned reflexes are a function of the "nearest subcortex". This general expression refers to the thalamus, hypothalamus, and other parts of the diencephalon and midbrain. However, later, with the development of ideas about the cortical representations of the unconditioned reflex, this point of view was also transferred to the concept of complex unconditioned reflexes. Thus, a complex unconditioned reflex, for example, an emotional discharge, has a specific subcortical part in its composition, but at the same time, the very course of this complex unconditioned reflex at each individual stage has a representation in the cerebral cortex. This point of view of I.P. Pavlov was confirmed by research recent years using the neuroscience method. It has been shown that a number of cortical regions, for example, the orbital cortex, the limbic region, are directly related to the emotional manifestations of animals and humans.

According to I.P. Pavlov, complex unconditioned reflexes (emotions) are "blind force" or "the main source of force" for cortical cells. The statements made by I. P. Pavlov about complex unconditioned reflexes and their role in the formation of conditioned reflexes at that time were only at the stage of the most general development, and only in connection with the discovery of the physiological characteristics of the hypothalamus, the reticular formation of the brain stem, it became possible to study this Problems.

From the point of view of IP Pavlov, the instinctive activity of animals, which includes several different stages of animal behavior, is also a complex unconditioned reflex. The features of this type of unconditioned reflex are that the individual stages of the performance of any instinctive action are connected with each other according to the principle of a chain reflex; however, later it was shown that each such stage of behavior must necessarily have a reverse afferentation) from the results of the action itself, that is, to carry out the process of comparing the actually obtained result with the previously predicted one. Only then can the next stage of behavior be formed.

In the process of studying the pain unconditioned reflex, it was revealed that pain excitation undergoes significant transformations at the level of the brain stem and hypothalamus. Of these structures, unconditioned excitation generally covers all areas of the cerebral cortex simultaneously. Thus, along with the mobilization in the cerebral cortex of the systemic connections inherent in a given unconditioned excitation and forming the basis of the cortical representation of the unconditioned reflex, unconditioned stimulation also produces a generalized effect on the entire cerebral cortex. In electroencephalographic analysis of cortical activity, this generalized effect of an unconditioned stimulus on the cerebral cortex manifests itself in the form of desynchronization of cortical wave electrical activity. The conduction of unconditional pain excitation to the cerebral cortex can be blocked at the level of the brain stem with the help of a special substance - aminazine. After the introduction of this substance into the blood, even a strong damaging (nociceptive) unconditioned excitation (burn hot water) does not reach the cerebral cortex and does not change its electrical activity.

Development of unconditioned reflexes in the embryonic period

The innate nature of the unconditioned reflex is especially clearly revealed in studies of the embryonic development of animals and humans. On the different terms embryogenesis, it is possible to trace each stage of the structural and functional formation of the unconditioned reflex. The vital functional systems of the newborn are fully consolidated by the time of birth. Separate links of a sometimes complex unconditioned reflex, such as the sucking reflex, include various parts of the body, often at a considerable distance from each other. Nevertheless, they are selectively combined by various connections and gradually form a functional whole. The study of the maturation of the unconditioned reflex in embryogenesis makes it possible to understand the constant and relatively unchanging adaptive effect of the unconditioned reflex when an appropriate stimulus is applied. This property of the unconditioned reflex is associated with the formation of interneuronal relationships based on morphogenetic and genetic patterns.

The maturation of the unconditioned reflex in the embryonic period is not the same for all animals. Since the maturation of the functional systems of the embryo has the most important biological meaning in preserving the life of a newborn of a given animal species, then, depending on the characteristics of the conditions for the existence of each animal species, the nature of structural maturation and the final formation of the unconditioned reflex will exactly correspond to the characteristics of this species.

Thus, for example, the structural design of the spinal reflexes of coordination is different in birds, which immediately become completely independent after hatching from the egg (chicken), and in birds that, after hatching from the egg, are helpless for a long time and are in the care of their parents (rooks). While the chick stands on its feet immediately after hatching and uses them completely freely every other day, in the rook, on the contrary, the forelimbs, that is, the wings, are the first to come into action.

This selective growth of the nervous structures of the unconditioned reflex takes place even more clearly in the development of the human fetus. The very first and clearly manifested motor reaction of the human fetus is a grasping reflex; it is detected as early as the 4th month of intrauterine life and is caused by the application of any solid object to the palm of the fetus. Morphological analysis of all links of this reflex convinces us that before it is revealed, a number of nervous structures differentiate into mature neurons and unite with each other. Myelination of the nerve trunks related to the flexors of the fingers begins and ends before this process unfolds in the nerve trunks of other muscles.

Phylogenetic development of unconditioned reflexes

According to the well-known position of I.P. Pavlov, unconditioned reflexes are the result of fixing by natural selection and heredity those reactions acquired over millennia that correspond to repeated environmental factors and are useful for a given species.

There is reason to believe that the fastest and most successful adaptations of an organism may depend on favorable mutations, which are subsequently selected by natural selection and are already inherited.

Bibliography: Anokhin P.K. Biology and neurophysiology of the conditioned reflex, M., 1968, bibliogr.; Afferent link of interoceptive reflexes, ed. Edited by I. A. Bulygina. Moscow, 1964. Vedyaev F. P. Subcortical mechanisms of complex motor reflexes, JI., 1965, bibliogr.; Vinogradova O. S. Orienting reflex and its neurophysiological mechanisms, M., 1961, bibliogr.; Groysman S. D. and Dekush P. G. Attempt of a quantitative research of intestinal reflexes, Pat. physiol. and Experiment, ter., v. 3, p. 51, 1974, bibliogr.; Orbeli JI. A. Questions of higher nervous activity, p. 146, M.-JI., 1949; Pavlov I.P. Complete works, vol. 1-6, M., 1951 - 1952; Petukhov BN Closing after the loss of the main unconditioned reflexes, Proceedings of the Center, Institute of Improvements. doctors, t. 81, p. 54, M., 1965, bibliography; Salch e n to about IN The latent periods of the myotatic reflexes providing motive interactions of people, Fiziol. man, vol. 1, Jvft 2, p. 317, 197 5, bibliography; Sechenov I. M. Reflexes of the brain, M., 1961; Slonim AD Fundamentals of general economic physiology of mammals, p. 72, M, -JI., 1961, bibliogr.; Human Physiology, ed. E. B. Babsky, p. 592, M., 1972; Frank Stein S. I. Respiratory reflexes and mechanisms of shortness of breath, M., 1974, bibliogr.; Shu with t and NA N. Analysis of unconditioned reflexes in the light of the doctrine of the dominant, Fiziol, zhurn. USSR, vol. 61, JSft 6, p. 855, 1975, bibliography; Human reflexes, pathophysiology of motor systems, ed. by J. E. Desment, Basel a. o., 1973; Mechanisms of orienting reaction in man, ed. by I. Ruttkay-Nedecky a. o., Bratislava, 1967.

Higher nervous activity- a system that allows the human body and animals to adapt to variable environmental conditions. Evolutionarily, vertebrates have developed a number of innate reflexes, but their existence is not enough for successful development.

In the process of individual development, new adaptive reactions are formed - these are conditioned reflexes. An outstanding domestic scientist I.P. Pavlov is the founder of the doctrine of unconditioned and conditioned reflexes. He formed a conditioned reflex theory, which states that the acquisition of a conditioned reflex is possible when a physiologically indifferent stimulus acts on the body. As a result, a more complex system of reflex activity is formed.

I.P. Pavlov - the founder of the doctrine of unconditioned and conditioned reflexes

An example of this is Pavlov's study of dogs that salivated in response to a sound stimulus. Pavlov also showed that innate reflexes are formed at the level of subcortical structures, and new connections are formed in the cerebral cortex throughout the life of an individual under the influence of constant stimuli.

Conditioned reflexes

Conditioned reflexes are formed on the basis of unconditional, in the process of individual development of the organism, against the background of a changing external environment.

reflex arc The conditioned reflex consists of three components: afferent, intermediate (intercalary) and efferent. These links carry out the perception of irritation, the transmission of an impulse to the cortical structures and the formation of a response.

The reflex arc of the somatic reflex performs motor functions (for example, flexion movement) and has the following reflex arc:

The sensitive receptor perceives the stimulus, then the impulse goes to the posterior horns of the spinal cord, where the intercalary neuron is located. Through it, the impulse is transmitted to the motor fibers and the process ends with the formation of movement - flexion.

A necessary condition for the development of conditioned reflexes is:

• The presence of a signal that precedes the unconditional;
• the stimulus that will cause the catching reflex must be inferior in strength to the biologically significant effect;
• the normal functioning of the cerebral cortex and the absence of distractions are mandatory.

Conditioned reflexes are not formed instantly. They are formed for a long time under the constant observance of the above conditions. In the process of formation, the reaction either fades away, then resumes again, until a stable reflex activity sets in.

An example of the development of a conditioned reflex

Classification of conditioned reflexes:

1. A conditioned reflex formed on the basis of the interaction of unconditioned and conditioned stimuli is called reflex of the first order.
2. Based on the classical acquired reflex of the first order, a second order reflex.

Thus, a defensive reflex of the third order was formed in dogs, the fourth could not be developed, and the digestive one reached the second. In children, conditioned reflexes of the sixth order are formed, in an adult up to the twentieth.

The variability of the external environment leads to the constant formation of many new behaviors necessary for survival. Depending on the structure of the receptor that perceives the stimulus, conditioned reflexes are divided into:

• Exteroceptive- irritation is perceived by body receptors, dominated by reflex reactions (gustatory, tactile);
• intraceptive- are called upon action on internal organs(changes in homeostasis, blood acidity, temperature);
• proprioceptive- are formed by stimulating the striated muscles of humans and animals, providing motor activity.

There are artificial and natural acquired reflexes:

artificial arise under the action of a stimulus that has no connection with an unconditioned stimulus (sound signals, light stimulation).

natural are formed in the presence of a stimulus similar to the unconditioned (smell and taste of food).

Unconditioned reflexes

These are innate mechanisms that ensure the preservation of the integrity of the body, homeostasis of the internal environment and, most importantly, reproduction. Congenital reflex activity is formed in the spinal cord and cerebellum, controlled by the cerebral cortex. Characteristically, they persist for life.

reflex arcs hereditary reactions are laid down before the birth of a person. Some reactions are characteristic of a certain age, and then disappear (for example, in small children - sucking, grasping, searching). Others do not manifest themselves at first, but with the onset of a certain period they appear (sexual).

Unconditioned reflexes are characterized by the following features:

• Occur independently of the consciousness and will of a person;
• species - appear in all representatives (for example, coughing, salivation at the smell or sight of food);
• endowed with specificity - appear when exposed to the receptor (pupil reaction occurs when a beam of light is directed to photosensitive areas). This also includes salivation, secretion of mucous secretions and enzymes of the digestive system when food enters the mouth;
• flexibility - for example, different foods lead to the secretion of a certain amount and various chemical composition of saliva;
• on the basis of unconditioned reflexes, conditioned ones are formed.

Unconditioned reflexes are needed to fulfill the needs of the body, they are permanent, but as a result of illness or bad habits they can disappear. So, with a disease of the iris of the eye, when scars form on it, the reaction of the pupil to light exposure disappears.

Classification of unconditioned reflexes

Congenital reactions are classified into:

• Simple(quickly remove your hand from a hot object);
• complex(maintaining homeostasis in situations of increased CO 2 concentration in the blood by increasing the frequency of respiratory movements);
• the most difficult(instinctive behavior).

Classification of unconditioned reflexes according to Pavlov

Pavlov divided innate reactions into food, sexual, protective, orienting, statokinetic, homeostatic.

To food salivation at the sight of food and its entry into the digestive tract, the secretion of hydrochloric acid, gastrointestinal motility, sucking, swallowing, chewing.

Protective are accompanied by contraction of muscle fibers in response to an irritating factor. Everyone knows the situation when the hand reflexively withdraws from a hot iron or a sharp knife, sneezing, coughing, lacrimation.

indicative occur when sudden changes occur in nature or in the organism itself. For example, turning the head and body towards sounds, turning the head and eyes to light stimuli.

Sexual associated with reproduction, preservation of the species, this includes parental (feeding and caring for offspring).

Statokinetic provide bipedalism, balance, movement of the body.

homeostatic- independent regulation of blood pressure, vascular tone, respiratory rate, heart rate.

Classification of unconditioned reflexes according to Simonov

vital to maintain life (sleep, nutrition, economy of strength), depend only on the individual.

role-playing arise upon contact with other individuals (procreation, parental instinct).

The need for self-development(the desire for individual growth, for the discovery of something new).

Congenital reflexes are activated when necessary due to a short-term violation of internal constancy or variability of the external environment.

Table comparing conditioned and unconditioned reflexes

Comparison of the characteristics of conditioned (acquired) and unconditioned (innate) reflexes
Unconditional	Conditional
Congenital	Acquired in the course of life
Present in all members of the species	Individual for each organism
Relatively constant	Arise and fade with changes in the external environment
Formed at the level of the spinal cord and medulla oblongata	Carried out by the brain
Are laid in utero	Developed against the background of congenital reflexes
Occurs when an irritant acts on certain receptor zones	Manifested under the influence of any stimulus that is perceived by the individual

Higher nervous activity carries out work in the presence of two interrelated phenomena: excitation and inhibition (congenital or acquired).

Braking

External unconditional braking(congenital) is carried out by the action on the body of a very strong stimulus. The termination of the action of the conditioned reflex occurs due to the activation of the nerve centers under the influence of a new stimulus (this is transcendental inhibition).

When several stimuli (light, sound, smell) are simultaneously exposed to the studied organism, the conditioned reflex fades, but over time, the orienting reflex is activated and inhibition disappears. This type of inhibition is called temporary.

Conditional inhibition(acquired) does not arise by itself, it must be worked out. There are 4 types of conditional inhibition:

• Fading (disappearance of a persistent conditioned reflex without constant reinforcement by an unconditioned one);
• differentiation;
• conditional brake;
• delayed braking.

Braking is a necessary process in our life. In its absence, many unnecessary reactions would occur in the body that are not beneficial.

An example of external inhibition (the reaction of a dog to a cat and the SIT command)

The meaning of conditioned and unconditioned reflexes

Unconditioned reflex activity is necessary for the survival and preservation of the species. good example is the birth of a child. In the new world for him, many dangers await him. Due to the presence of innate reactions, the cub can survive in these conditions. Activated immediately after birth respiratory system, the sucking reflex provides nutrients, touching sharp and hot objects is accompanied by an instant withdrawal of the hand (manifestation of protective reactions).

For further development and existence, one has to adapt to the surrounding conditions, conditioned reflexes help in this. They provide rapid adaptation of the body and can be formed throughout life.

The presence of conditioned reflexes in animals enables them to quickly respond to the voice of a predator and save their lives. A person at the sight of food carries out conditioned reflex activity, salivation begins, the production of gastric juice for the rapid digestion of food. The sight and smell of some objects, on the contrary, signals danger: the red cap of fly agaric, the smell of spoiled food.

The importance of conditioned reflexes in the daily life of man and animals is enormous. Reflexes help to navigate the terrain, get food, get away from danger, saving one's life.

Conditioned reflexes are reactions of the whole organism or any part of it to external or internal stimuli. They manifest themselves through the disappearance, weakening or strengthening of certain activities.

Conditioned reflexes are helpers of the body, allowing it to quickly respond to any changes and adapt to them.

Story

For the first time, the idea of ​​a conditioned reflex was put forward by the French philosopher and scientist R. Descartes. Somewhat later, the Russian physiologist I. Sechenov created and experimentally proved a new theory regarding the reactions of the body. For the first time in the history of physiology, it was concluded that conditioned reflexes are a mechanism that is activated not only in its work, the entire nervous system is involved. This allows the body to maintain contact with the environment.

Studied Pavlov. This outstanding Russian scientist was able to explain the mechanism of action of the cerebral cortex and cerebral hemispheres. At the beginning of the 20th century, he created the theory of conditioned reflexes. This scientific work has become a real revolution in physiology. Scientists have proven that conditioned reflexes are reactions of the body that are acquired throughout life, based on unconditioned reflexes.

instincts

Certain reflexes of an unconditioned type are characteristic of each type of living organism. They are called instincts. Some of them are quite complex. Examples of this are bees that make honeycombs, or birds that build nests. Due to the presence of instincts, the body is able to optimally adapt to environmental conditions.

Are congenital. They are inherited. In addition, they are classified as species, since they are characteristic of all representatives of a particular species. Instincts are permanent and persist throughout life. They manifest themselves to adequate stimuli that are attached to a specific single receptive field. Physiologically, unconditioned reflexes are closed in the brainstem and at the level of the spinal cord. They are manifested through anatomically expressed

As for the monkey and man, the implementation of most of the complex unconditioned reflexes is impossible without the participation of the cerebral cortex. When its integrity is violated, pathological changes in unconditioned reflexes occur, and some of them simply disappear.

Classification of instincts

Unconditioned reflexes are very strong. Only under certain conditions, when their manifestation becomes optional, they can disappear. For example, the canary, domesticated about three hundred years ago, does not currently have the instinct to make a nest. There are the following types of unconditioned reflexes:

Which is the body's response to a variety of physical or chemical stimuli. Such reflexes, in turn, may be local (withdrawal of the hand) or complex (flight from danger).
- Food instinct, which is caused by hunger and appetite. This unconditioned reflex includes a whole chain of sequential actions - from searching for prey to attacking it and further eating.
- Parental and sexual instincts associated with the maintenance and reproduction of the species.

Comfort instinct for keeping the body clean (bathing, scratching, shaking, etc.).
- Approximate instinct, when the eyes and head turn towards the stimulus. This reflex is necessary to save life.
- The instinct of freedom, which is especially pronounced in the behavior of animals in captivity. They constantly want to break free and often die, refusing water and food.

The emergence of conditioned reflexes

In the course of life, acquired reactions of the organism are added to the inherited instincts. They are called conditioned reflexes. They are acquired by the body as a result of individual development. The basis for obtaining conditioned reflexes is life experience. Unlike instincts, these reactions are individual. They may be present in some members of the species and absent in others. In addition, a conditioned reflex is a reaction that may not persist throughout life. Under certain conditions, it is produced, fixed, disappears. Conditioned reflexes are reactions that can occur to various stimuli applied to different receptor fields. This is their difference from instincts.

The mechanism of the conditioned reflex closes at the level. If it is removed, then only instincts remain.

The formation of conditioned reflexes occurs on the basis of unconditioned ones. For the implementation of this process, a certain condition must be met. At the same time, any change in the external environment must be combined in time with the internal state of the organism and perceived by the cerebral cortex with a simultaneous unconditional reaction of the organism. Only in this case does a conditioned stimulus or signal appear that contributes to the emergence of a conditioned reflex.

Examples

For the appearance of such a reaction of the body as the release of saliva at the ringing of knives and forks, as well as at the knock of a cup for feeding an animal (in humans and dogs, respectively), an indispensable condition is the repeated coincidence of these sounds with the process of providing food.

In the same way, the sound of a bell or the switching on of a light bulb will cause the dog's paw to flex if these phenomena are repeatedly accompanied by electrical stimulation of the animal's leg, as a result of which an unconditioned flexion reflex appears.

The conditioned reflex is pulling the child's hands away from the fire and then crying. However, these phenomena will take place only if the type of fire, even once, coincided with the receipt of a burn.

Reaction components

The body's response to irritation is a change in breathing, secretion, movement, etc. As a rule, unconditioned reflexes are rather complex reactions. That is why they include several components at once. For example, a defensive reflex is accompanied not only by defensive movements, but also by an increase in breathing, an acceleration of the activity of the heart muscle, and a change in the composition of the blood. In this case, voice reactions may also appear. As for the food reflex, there are also respiratory, secretory and cardiovascular components.

Conditional reactions usually reproduce the structure of unconditioned ones. This occurs in connection with the excitation of stimuli of the same nerve centers.

Classification of conditioned reflexes

Acquired body responses to various stimuli are divided into types. Some of the existing classifications are of great importance in solving not only theoretical, but also practical problems. One of the areas of application of this knowledge is sports activities.

Natural and artificial reactions of the body

There are conditioned reflexes that arise under the action of signals characteristic of the constant properties of unconditioned stimuli. An example of this is the sight and smell of food. Such conditioned reflexes are natural. They are characterized by the speed of production and great durability. Natural reflexes, even in the absence of subsequent reinforcement, can be maintained throughout life. The value of the conditioned reflex is especially great at the very first stages of the life of the organism, when it adapts to the environment.
However, reactions can also be developed to a variety of indifferent signals, such as smell, sound, temperature changes, light, etc. Under natural conditions, they are not irritants. It is these reactions that are called artificial. They are developed slowly and in the absence of reinforcement quickly disappear. For example, artificial conditioned human reflexes are reactions to the sound of a bell, touching the skin, weakening or strengthening lighting, etc.

First and highest order

There are such types of conditioned reflexes that are formed on the basis of unconditioned ones. These are first order reactions. There are also higher categories. So, reactions that are developed on the basis of already existing conditioned reflexes are referred to as reactions of a higher order. How do they arise? During the development of such conditioned reflexes, the indifferent signal is reinforced with well-learned conditioned stimuli.

For example, irritation in the form of a call is constantly reinforced by food. In this case, a first-order conditioned reflex is developed. On its basis, a reaction to another stimulus, for example, to light, can be fixed. This will become a second-order conditioned reflex.

Positive and negative reactions

Conditioned reflexes can affect the activity of the body. Such reactions are considered positive. The manifestation of these conditioned reflexes can be secretory or motor functions. If there is no activity of the organism, then the reactions are classified as negative. For the process of adaptation to the constantly changing conditions of the environment of existence, both one and the second type are of great importance.

At the same time, there is a close relationship between them, since when one kind of activity is manifested, another is certainly oppressed. For example, when the command “Attention!” Sounds, the muscles are in a certain position. At the same time, motor reactions (running, walking, etc.) are inhibited.

Mechanism of education

Conditioned reflexes arise with the simultaneous action of a conditioned stimulus and an unconditioned reflex. In this case, certain conditions must be met:

The unconditioned reflex is biologically stronger;
- the manifestation of the conditioned stimulus is somewhat ahead of the action of the instinct;
- the conditioned stimulus is necessarily reinforced by the influence of the unconditioned;
- the body must be in a waking state and be healthy;
- the condition of the absence of extraneous stimuli producing a distracting effect is observed.

The centers of conditioned reflexes located in the cerebral cortex establish a temporary connection (short circuit) between themselves. In this case, stimulation is perceived by cortical neurons, which are part of the arc of the unconditioned reflex.

Inhibition of conditioned reactions

In order to ensure adequate behavior of the organism and for better adaptation to environmental conditions, the development of conditioned reflexes alone will not be enough. It will take the opposite direction of action. It is the inhibition of conditioned reflexes. This is the process of eliminating those reactions of the body that are not necessary. According to the theory developed by Pavlov, certain types of cortical inhibition are distinguished. The first of these is the unconditional. It appears as a response to the action of some extraneous stimulus. There is also internal inhibition. It's called conditional.

External braking

This reaction received such a name due to the fact that its development is facilitated by the processes taking place in those parts of the cortex that do not take part in the implementation of reflex activity. For example, a foreign smell, sound, or change in lighting before the food reflex begins can reduce it or contribute to its complete disappearance. The new stimulus acts as a brake on the conditioned response.

Food reflexes can also be eliminated by painful stimuli. The overflow of the bladder, vomiting, internal inflammatory processes, etc. contribute to the inhibition of the reaction of the body. All of them inhibit food reflexes.

Internal braking

It occurs when the received signal is not reinforced by an unconditioned stimulus. Internal inhibition of conditioned reflexes occurs if, for example, an electric light bulb is periodically turned on in front of the eyes of an animal during the day, without bringing food. It has been experimentally proven that saliva production will decrease each time. As a result, the reaction will die out completely. However, the reflex will not disappear without a trace. He just slows down. This has also been proven experimentally.

Conditioned inhibition of conditioned reflexes can be eliminated the very next day. However, if this is not done, then the reaction of the body to this stimulus will subsequently disappear forever.

Varieties of internal inhibition

Classify several types of elimination of the body's response to stimuli. Thus, at the basis of the disappearance of conditioned reflexes, which are simply not needed under given specific conditions, is extinction inhibition. There is another variation of this phenomenon. This is a distinctive, or differentiated inhibition. So, the animal can distinguish the number of beats of the metronome at which food is brought to it. This happens when the given conditioned reflex has been previously worked out. The animal distinguishes stimuli. This reaction is based on internal inhibition.

The Importance of Eliminating Reactions

Conditioned inhibition plays a significant role in the life of the organism. Thanks to him, the process of adaptation to the environment is much better. Possibility of orientation in various difficult situations gives a combination of excitation and inhibition, which are two forms of a single nervous process.

Conclusion

There are an infinite number of conditioned reflexes. They are the factor that determines the behavior of a living organism. With the help of conditioned reflexes, animals and humans adapt to their environment.

There are many indirect signs of body reactions that have a signal value. For example, an animal, knowing in advance about the approach of danger, builds its behavior in a certain way.

The process of developing conditioned reflexes, which belong to the highest order, is a synthesis of temporary connections.

The basic principles and regularities manifested in the formation of not only complex, but also elementary reactions are the same for all living organisms. This leads to an important conclusion for philosophy and natural sciences that cannot but obey the general laws of biology. In this regard, it can be studied objectively. However, it should be borne in mind that the activity of the human brain has a qualitative specificity and a fundamental difference from the work of the brain of an animal.