What does conditioned and unconditioned reflex mean? Reflexes: conditioned and unconditioned

“If the animal were not... accurately adapted to the outside world, then it would soon or slowly cease to exist... It should react to the outside world in such a way that its existence would be ensured by all its response activity.”
I.P. Pavlov.

The adaptation of animals and humans to changing conditions of existence in the external environment is ensured by the activity of the nervous system and is realized through reflex activity. In the process of evolution, hereditarily fixed reactions (unconditioned reflexes) arose that combine and coordinate the functions of various organs and carry out adaptation of the body. In humans and higher animals, in the process of individual life, qualitatively new reflex reactions arise, which I. P. Pavlov called conditioned reflexes, considering them the most perfect form of adaptation.

While relatively simple forms of nervous activity determine the reflex regulation of homeostasis and autonomic functions of the body, higher nervous activity (HNA) provides complex individual forms of behavior in changing living conditions. GNI is realized due to the dominant influence of the cortex on all underlying structures of the central nervous system. The main processes that dynamically replace each other in the central nervous system are the processes of excitation and inhibition. Depending on their ratio, strength and localization, the control influences of the cortex are built. The functional unit of the GNI is the conditioned reflex.

Higher nervous activity is a set of unconditioned and conditioned reflexes, as well as higher mental functions that ensure adequate behavior in changing natural and social conditions. For the first time, the assumption about the reflex nature of the activity of the higher parts of the brain was made by I.M. Sechenov, which made it possible to extend the reflex principle to human mental activity. The ideas of I.M. Sechenov received experimental confirmation in the works of I.P. Pavlov, who developed a method for objective assessment of the functions of the higher parts of the brain - the method of conditioned reflexes.

I.P. Pavlov showed that all reflex reactions can be divided into two groups: unconditional and conditional.

Unconditioned reflexes can be simple or complex. Complex innate unconditional reflex reactions are called instincts. Their characteristic feature is the chain nature of the reactions.

Conditioned reflex is a complex multicomponent reaction that is developed on the basis of unconditioned reflexes using a previous indifferent stimulus. It has a signaling character, and the body meets the impact of an unconditioned stimulus prepared. For example, in the pre-launch period, blood is redistributed, breathing and blood circulation are increased, and when the muscle load begins, the body is already prepared for it.

To develop a conditioned reflex it is necessary:

1) the presence of two stimuli, one of which is unconditioned (food, painful stimulus, etc.), causing an unconditioned reflex reaction, and the other is conditioned (signal), signaling the upcoming unconditional stimulus (light, sound, type of food, etc. .);
2) multiple combinations of conditioned and unconditioned stimuli (although the formation of a conditioned reflex is possible with their single combination);
3) the conditioned stimulus must precede the action of the unconditional;
4) any stimulus from the external or internal environment can be used as a conditioned stimulus, which should be as indifferent as possible, not cause a defensive reaction, not have excessive force and be able to attract attention;
5) the unconditioned stimulus must be strong enough, otherwise a temporary connection will not be formed;
6) arousal from an unconditioned stimulus should be stronger than from a conditioned one;
7) it is necessary to eliminate extraneous stimuli, as they can cause inhibition of the conditioned reflex;
8) the animal in which the conditioned reflex is developed must be healthy;
9) when developing a conditioned reflex, motivation must be expressed, for example, when developing a food salivary reflex, the animal must be hungry, but in a well-fed animal, this reflex is not developed.

Conditioned reflexes are easier to develop in response to environmentally similar influences for a given animal. In this regard, conditioned reflexes are divided into natural and artificial. Natural conditioned reflexes are developed to agents that, under natural conditions, act together with a stimulus that causes an unconditioned reflex (for example, the type of food, its smell, etc.). All other conditioned reflexes are artificial, i.e. are produced in response to agents that are not normally associated with the action of an unconditioned stimulus, for example, the food salivary reflex to a bell.

The physiological basis for the emergence of conditioned reflexes is the formation of functional temporary connections in the higher parts of the central nervous system.

Consequently, the first way of forming a temporary connection between the cortical representations of the conditioned and unconditioned reflexes is intracortical. However, when the cortical representation of the conditioned reflex is destroyed, the developed conditioned reflex is preserved. Apparently, the formation of a temporary connection occurs between the subcortical center of the conditioned reflex and the cortical center of the unconditioned reflex. When the cortical representation of the unconditioned reflex is destroyed, the conditioned reflex is also preserved. Consequently, the development of a temporary connection can occur between the cortical center of the conditioned reflex and the subcortical center of the unconditioned reflex.

Separation of the cortical centers of the conditioned and unconditioned reflexes by crossing the cerebral cortex does not prevent the formation of the conditioned reflex.

There are different opinions on the issue of the mechanisms for the formation of temporary connections. Perhaps the formation of a temporary connection occurs according to the dominant principle. The source of excitation from an unconditioned stimulus is always stronger than from a conditioned one, since the unconditioned stimulus is always biologically more significant for the animal. This focus of excitation is dominant, therefore attracts excitation from the focus of conditioned stimulation. If the excitation has passed along some nerve circuits, then next time it will pass along these paths much easier (the phenomenon of “blazing a path”). This is based on: the summation of excitations, a long-term increase in the excitability of synaptic formations, an increase in the amount of mediator in synapses, and an increase in the formation of new synapses. All this creates structural prerequisites for facilitating the movement of excitation along certain neural circuits.

Another idea about the mechanism of formation of a temporary connection is the convergent theory. It is based on the ability of neurons to respond to stimulation of different modalities. According to P.K. Anokhin, conditioned and unconditioned stimuli cause widespread activation of cortical neurons due to the inclusion of the reticular formation. As a result, the ascending signals (conditioned and unconditioned stimuli) overlap, i.e. these excitations meet on the same cortical neurons. As a result of the convergence of excitations, temporary connections arise and stabilize between the cortical representations of the conditioned and unconditioned stimuli.

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

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 arise 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 at the sight of a 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 line.
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.

Conditioned and unconditioned reflexes are characteristic of the entire animal world.

In biology, they are considered as the result of a long evolutionary process and represent the response of the central nervous system to external environmental influences.

They provide a very quick response to a particular stimulus, thereby significantly saving the resources of the nervous system.

Classification of reflexes

In modern science, such reactions are described using several classifications that describe their features in different ways.

So, they come in the following types:

1. Conditional and unconditional - depending on how they are formed.
2. Exteroceptive (from “extra” - external) - reactions of external receptors of the skin, hearing, smell and vision. Interoreceptive (from “intero” - inside) - reactions of internal organs and systems. Proprioceptive (from “proprio” - special) - reactions associated with the sensation of one’s own body in space and formed by the interaction of muscles, tendons and joints. This is a classification based on receptor type.
3. Based on the type of effectors (zones of reflex response to information collected by receptors), they are divided into: motor and autonomic.
4. Classification based on specific biological role. There are species aimed at protection, nutrition, orientation in the environment and reproduction.
5. Monosynaptic and polysynaptic - depending on the complexity of the neural structure.
6. According to the type of influence, excitatory and inhibitory reflexes are distinguished.
7. And based on where the reflex arcs are located, they are divided into cerebral (various parts of the brain are included) and spinal (neurons of the spinal cord are included).

What is a conditioned reflex

This is a term denoting a reflex formed as a result of the fact that simultaneously for a long time a stimulus that does not cause any reaction is presented with a stimulus that causes some specific unconditioned reflex. That is, the reflex response eventually extends to an initially indifferent stimulus.

Where are the centers of conditioned reflexes located?

Since this is a more complex product of the nervous system, the central part of the neural arc of conditioned reflexes is located in the brain, specifically in the cerebral cortex.

Examples of conditioned reflexes

The most striking and classic example is Pavlov’s dog. The dogs were presented with a piece of meat (this caused the secretion of gastric juice and salivation) along with the inclusion of a lamp. As a result, after a while, the process of activating digestion started when the lamp was turned on.

A familiar example from life is the feeling of cheerfulness from the smell of coffee. Caffeine does not yet have a direct effect on the nervous system. He is outside the body - in a circle. But the feeling of vigor is triggered only by the smell.

Many mechanical actions and habits are also examples. We rearranged the furniture in the room, and the hand reaches in the direction where the closet used to be. Or a cat who runs to the bowl when he hears the rustling of a box of food.

The difference between unconditioned reflexes and conditioned ones

They differ in that unconditional ones are innate. They are the same for all animals of one species or another, as they are inherited. They are quite unchanged throughout the life of a person or animal. From birth and always occur in response to receptor irritation, and are not produced.

Conditional ones are acquired throughout life, with experience in interaction with the environment. Therefore, they are quite individual - depending on the conditions under which it was formed. They are unstable throughout life and can fade away if they do not receive reinforcement.

Conditioned and unconditioned reflexes - comparison table

The difference between instincts and unconditioned reflexes

Instinct, like reflex, is a biologically significant form of animal behavior. Only the second is a simple short response to a stimulus, and instinct is a more complex activity that has a specific biological goal.

The unconditioned reflex is always triggered. But instinct is only in a state of biological readiness of the body to trigger this or that behavior. For example, mating behavior in birds is triggered only during a certain period of the year when chick survival may be maximum.

What is not typical for unconditioned reflexes?

In short, they cannot change during life. They do not differ between different animals of the same species. They cannot disappear or stop appearing in response to a stimulus.

When conditioned reflexes fade

Extinction occurs as a result of the fact that the stimulus (stimulus) ceases to coincide in time of presentation with the stimulus that caused the reaction. Need reinforcements. Otherwise, without being reinforced, they lose their biological significance and fade away.

Unconditioned reflexes of the brain

These include the following types: blinking, swallowing, vomiting, orientation, maintaining balance associated with hunger and satiety, braking movement in inertia (for example, during a push).

The disruption or disappearance of any type of these reflexes can be a signal of serious disturbances in brain function.

Pulling your hand away from a hot object is an example of which reflex

An example of a painful reaction is pulling your hand away from a hot kettle. This is an unconditional look, the body's response to dangerous environmental influences.

Blink reflex - conditioned or unconditioned

The blink reaction is an unconditional type. It occurs as a result of dry eye and to protect against mechanical damage. All animals and humans have it.

Salivation in a person at the sight of a lemon - what is the reflex?

This is a conditional view. It is formed due to the fact that the rich taste of lemon provokes salivation so often and strongly that simply looking at it (and even remembering it) triggers a response.

How to develop a conditioned reflex in a person

In humans, unlike animals, the conditioned appearance is developed faster. But for all, the mechanism is the same - joint presentation of stimuli. One, causing an unconditioned reflex, and the other, an indifferent one.

For example, for a teenager who falls off a bicycle while listening to some specific music, later unpleasant feelings that arise while listening to the same music can become the acquisition of a conditioned reflex.

What is the role of conditioned reflexes in the life of an animal

They enable an animal with rigid, unchanging unconditioned reactions and instincts to adapt to conditions that are constantly changing.

At the level of the entire species, this is the ability to live in the largest possible areas with different weather conditions, with different levels of food supply. In general, they provide the ability to react flexibly and adapt to the environment.

Conclusion

Unconditioned and conditioned responses are extremely important for the survival of an animal. But it is in interaction that they allow us to adapt, reproduce and raise the healthiest offspring possible.

Abstract on the topic:

"Conditioned and unconditioned reflexes"

Donetsk 2010

Introduction.

1. Teachings of I.P. Pavlov. Conditioned and unconditioned reflexes.

2. Classification of unconditioned reflexes.

3. The mechanism of formation of conditioned reflexes.

4. Conditions for the formation of conditioned reflexes.

5. Classification of conditioned reflexes.

Conclusion.

List of used literature.

Introduction.

The adaptation of animals and humans to changing conditions of existence in the external environment is ensured by the activity of the nervous system and is realized through reflex activity. In the process of evolution, hereditarily fixed reactions (unconditioned reflexes) arose that combine and coordinate the functions of various organs and carry out adaptation of the body. In humans and higher animals, in the process of individual life, qualitatively new reflex reactions arise, which I. P. Pavlov called conditioned reflexes, considering them the most perfect form of adaptation. A reflex is the body’s response to any stimulus, carried out with the participation of the central nervous system.

1. Teachings of I.P. Pavlov. Conditioned and unconditioned reflexes.

I.P. Pavlov, while studying the processes of digestion, drew attention to the fact that in a number of cases, when eating food, the dog observed salivation not for the food itself, but for various signals that were in one way or another associated with food. For example, saliva was secreted by the smell of food, the sound of dishes from which the dog was usually fed. Pavlov called this phenomenon “mental salivation” as opposed to “physiological.” The assumption that the dog “imagined” how a familiar person would feed it from a bowl in which food is usually placed was categorically rejected by Pavlov as unscientific.

Before Pavlov, physiology mainly used methods in which all the functions of various organs were studied in an animal under anesthesia. At the same time, the normal functioning of both organs and the central nervous system was disrupted, which could distort the research results. To study the work of the higher parts of the central nervous system, Pavlov used synthetic methods that made it possible to obtain information from a healthy animal without disrupting the functions of the body.

When studying the processes of digestion, Pavlov came to the conclusion that the basis of “mental” salivation, like physiological one, is reflex activity. In both cases, there is an external factor - a signal that triggers the salivary reaction. The difference lies only in the nature of this factor. With “physiological” salivation, the signal is the direct perception of food by the taste buds of the oral cavity, and with “mental” salivation, the stimulus will be indirect signals associated with food intake: the type of food, its smell, the type of dishes, etc. Based on this, Pavlov came to the conclusion that the “physiological” salivary reflex can be called unconditioned, and the “psychological” salivation can be called conditioned. Thus, according to Pavlov, the higher nervous activity of any animal organism is based on conditioned and unconditioned reflexes.

Unconditioned reflexes are very diverse; they are the basis of the instinctive activity of the body. Unconditioned reflexes are innate; they do not require special training. By the time of birth, the main hereditary fund of such reflexes is laid in animals and humans. But some of them, in particular the sexual ones, are formed after birth, as the nervous, endocrine and other systems undergo corresponding morphological and functional maturation.

Unconditioned reflexes provide the first, rough adaptation of the body to changes in the external and internal environment. Thus, the newborn’s body adapts to the environment through unconditioned reflexes of breathing, sucking, swallowing, etc.

Unconditioned reflexes are characterized by stability, which is determined by the presence in the central nervous system of ready-made, stable nerve connections for reflex excitation. These reflexes are specific in nature. Representatives of the same animal species have approximately the same fund of unconditioned reflexes. Each of them manifests itself upon stimulation of a specific receptive field (reflexogenic zone). For example, the pharyngeal reflex occurs when the posterior wall of the pharynx is irritated, the salivation reflex - when the receptors of the oral cavity are irritated, the knee, Achilles, elbow reflexes - when the receptors of the tendons of certain muscles are irritated, the pupillary - when a sharp change in illumination acts on the retina, etc. With irritation These reactions are not evoked by other receptive fields.

Most unconditioned reflexes can occur without the participation of the cerebral cortex and subcortical nodes. At the same time, the Centers of unconditioned reflexes are under the control of the cerebral cortex and subcortical nodes, which have a subordination (from the Latin sub - submission, ordinatio - putting in order) influence.

During the growth and development of the organism, the system of unconditional reflex connections still turns out to be limited, inert, and unable to provide sufficiently mobile adaptation reactions corresponding to fluctuations in the external and internal environment. More perfect adaptation of the body to constantly changing conditions of existence occurs thanks to conditioned reflex, i.e., individually acquired reactions. Conditioned reflex mechanisms of the brain are related to all types of activity of the body (to somatic and vegetative functions, to behavior), providing adaptive reactions aimed at maintaining the integrity and stability of the “organism-environment” system. I. P. Pavlov called a conditioned reflex a temporary connection between a stimulus and a response activity that occurs in the body under certain conditions. Therefore, in the literature, instead of the term “conditioned reflex,” the term “temporary connection” is often used, which includes more complex manifestations of animal and human activity, representing entire systems of reflexes and behavioral acts.

Conditioned reflexes are not innate and are acquired during life as a result of constant communication of the body with the external environment. They are not as stable as unconditioned reflexes and disappear in the absence of reinforcement. With these reflexes, responses can be associated with stimulation of a wide variety of receptive fields (reflexogenic zones). Thus, a conditioned food secretory reflex can be developed and reproduced by stimulation of different sense organs (vision, hearing, smell, etc.).

2. Classification of unconditioned reflexes.

The behavior of animals and humans is a complex interweaving of interconnected unconditioned and conditioned reflexes, which are sometimes difficult to distinguish.

The first classification of unconditioned reflexes was proposed by Pavlov. He identified six basic unconditioned reflexes:

1. food

2. defensive

3. genitals

4. approximate

5. parental

6. children's.

Food reflexes are associated with changes in the secretory and motor functioning of the organs of the digestive system and occur when receptors in the oral cavity and walls of the digestive tract are irritated. Examples include reflex reactions such as salivation and bile secretion, sucking, and the swallowing reflex.

Defensive reflexes - contractions of various muscle groups - occur in response to tactile or pain stimulation of receptors in the skin and mucous membranes, as well as under the action of strong visual, olfactory, sound or taste stimuli. Examples include withdrawal of the hand in response to the touch of a hot object, constriction of the pupil in harsh lighting.

Genital reflexes are associated with changes in the functions of the genital organs, caused by direct irritation of the corresponding receptors or the entry of sex hormones into the blood. These are reflexes associated with sexual intercourse.

Approximate Pavlov called the reflex the “what is it?” reflex. Such reflexes occur with sudden changes in the external environment surrounding the animal, or with internal changes in its body. The reaction consists of various acts of behavior that allow the body to become familiar with such changes. These can be reflex movements of the ears, head in the direction of the sound, or rotation of the body. Thanks to this reflex, a quick and timely response to all changes in the environment and in one’s body occurs. The difference between this unconditioned reflex and others is that when the action of the stimulus is repeated, it loses its indicative meaning.

Parental reflexes are reflexes that underlie care for offspring.

Children's reflexes are characteristic from birth and appear at certain, usually early, stages of development. An example of a child's reflex is the innate sucking reflex.

3. The mechanism of formation of conditioned reflexes.

According to I.P. Pavlov, a temporary connection is formed between the cortical center of the unconditioned reflex and the cortical center of the analyzer, the receptors of which are acted upon by the conditioned stimulus, i.e. the connection is made in the cerebral cortex. The closure of the temporary connection is based on the process of dominant interaction between excited centers. Impulses caused by an indifferent (conditioned) signal from any part of the skin and other sensory organs (eye, ear) enter the cerebral cortex and ensure the formation of a focus of excitation in it. If, after an indifferent signal, food reinforcement (feeding) is given, then a more powerful second focus of excitation arises in the cerebral cortex, to which the previously arisen and irradiating excitation along the cortex is directed. Repeated combination in experiments of a conditioned signal and an unconditioned stimulus facilitates the passage of impulses from the cortical center of the indifferent signal to the cortical representation of the unconditioned reflex - synaptic facilitation (blazing the path) - dominant. The conditioned reflex first becomes a dominant, and then a conditioned reflex.

I. P. Pavlov called the formation of a temporary connection in the cerebral cortex the closure of a new conditioned reflex arc: now the supply of only a conditioned signal leads to the excitation of the cortical center of the unconditioned reflex and excites it, i.e. a reflex to a conditioned stimulus occurs - a conditioned reflex.

4. Conditions for the formation of conditioned reflexes.

Conditioned reflexes are well formed only under certain conditions, the most important of which are:

1) repeated combination of the action of a previously indifferent conditioned stimulus with the action of a reinforcing unconditional or previously well-developed conditioned stimulus;

2) some precedence in time of the action of the indifferent agent to the action of the reinforcing stimulus;

3) vigorous state of the body;

4) absence of other types of active activity;

5) a sufficient degree of excitability of an unconditional or well-fixed conditioned reinforcing stimulus;

6) suprathreshold intensity of the conditioned stimulus.

The coincidence of the action of an indifferent stimulus with the action of a reinforcing stimulus (an unconditioned or previously well-established conditioned stimulus) must, as a rule, be repeated several times. When new conditioned reflexes are formed in the same environment, the process of formation of these reflexes accelerates. In humans, many conditioned reflexes, especially to verbal stimuli, can be formed after one combination.

The duration of time preceding the action of a new conditioned stimulus to the action of a reinforcer should not be significant. Thus, in dogs, reflexes are developed especially well when the duration of the precedence is 5-10 seconds. When combined in the reverse order, when the reinforcing stimulus begins to act earlier than the indifferent stimulus, the conditioned reflex is not developed.

The formation of conditioned reflex connections, which easily occurs in a vigorous state of the body, becomes difficult when it is inhibited. Thus, in animals that are in a drowsy state, conditioned reflexes are either not formed at all, or are formed slowly and with difficulty. The inhibited state makes it difficult for humans to form conditioned reflexes.

When centers not associated with the formation of these conditioned reflexes dominate in the central nervous system, the formation of these reflexes becomes difficult. So, if a dog experiences sudden excitement, for example, at the sight of a cat, then under these conditions the formation of a food salivary reflex to the sound of a bell or the light of a light bulb does not occur. In a person absorbed in some activity, the formation of conditioned reflexes to other types of activity at this time is also greatly hampered.

Conditioned reflexes are formed only if there is sufficient excitability of the centers of these reinforcing reflexes. For example, when developing conditioned food reflexes in dogs, experiments are carried out under conditions of high excitability of the food center (the animal is in a hungry state).

The emergence and consolidation of a conditioned reflex connection occurs at a certain level of excitation of the nerve centers. In this regard, the strength of the conditioned signal should be above the threshold, but not excessive. To weak stimuli, conditioned reflexes are not developed at all or are formed slowly and are unstable. Excessively strong stimuli cause the development of protective (extraordinary) inhibition in nerve cells, which also complicates or eliminates the possibility of the formation of conditioned reflexes.

5. Classification of conditioned reflexes.

Conditioned reflexes are divided according to several criteria.

1. By biological significance distinguish:

1) food;

2) sexual;

3) defensive;

4) motor;

5) indicative - reaction to a new stimulus.

The indicative reflex occurs in 2 phases:

1) stage of nonspecific anxiety - 1st reaction to a new stimulus: motor reactions, autonomic reactions change, the rhythm of the electroencephalogram changes. The duration of this stage depends on the strength and significance of the stimulus;

2) stage of exploratory behavior: motor activity, autonomic reactions, and electroencephalogram rhythm are restored. Excitation covers a large part of the cerebral cortex and the formation of the limbic system. The result is cognitive activity.

Differences between the orienting reflex and other conditioned reflexes:

1) innate reaction of the body;

2) it can fade away when the stimulus is repeated.

That is, the orienting reflex occupies an intermediate place between the unconditioned and conditioned reflex.

2. By type of receptors, from which development begins, conditioned reflexes are divided into:

1) exteroceptive - form the adaptive behavior of animals in obtaining food, avoiding harmful influences, procreation, etc. For a person, exteroceptive verbal stimuli that shape actions and thoughts are of utmost importance;

2) proprioceptive - they form the basis of teaching animals and humans motor skills: walking, production operations, etc.;

3) interoceptive – affect mood and performance.

3. By division of the nervous system and the nature of the efferent response distinguish:

1) somatic (motor);

2) vegetative (cardiovascular, secretory, excretory, etc.).

IN depending on production conditions natural conditional reflexes (the conditioned stimulus is not used) are formed in response to signals that are natural signs of the reinforcing stimulus. Since natural conditioned reflexes are difficult to measure quantitatively (smell, color, etc.), I. P. Pavlov later moved on to the study of artificial conditioned reflexes.

Artificial – conditioned reflexes to signal stimuli that in nature are not related to the unconditional (reinforced) stimulus, i.e. any additional stimulus is applied.

The main laboratory conditioned reflexes are the following.

1. By difficulties distinguish:

1) simple - produced in response to single stimuli (classical conditioned reflexes of I. P. Pavlov);

2) complex – generated by several signals acting simultaneously or sequentially;

3) chain - produced by a chain of stimuli, each of which causes its own conditioned reflex.

2. By the ratio of the time of action of conditioned and unconditioned stimuli distinguish:

1) cash – development is characterized by the coincidence of the actions of conditioned and unconditioned stimuli, the latter is turned on later;

2) trace – produced under conditions when the unconditioned stimulus is presented 2-3 minutes after the conditioned stimulus is turned off, i.e. The development of a conditioned reflex occurs in response to a signal stimulus.

3. By development of a conditioned reflex on the basis of another conditioned reflex distinguish conditioned reflexes of the second, third and other orders.

1) first-order reflexes – conditioned reflexes developed on the basis of unconditioned reflexes;

2) second-order reflexes – developed on the basis of first-order conditioned reflexes, in which there is no unconditioned stimulus;

3) third-order reflex - developed on the basis of a conditioned second order.

The higher the order of conditioned reflexes, the more difficult it is to develop them.

IN depending on the signaling system distinguish conditioned reflexes to signals of the first and second signaling systems, i.e. In other words, the latter are produced only in humans.

According to the body's reactions, conditioned reflexes are positive and negative.

Conclusion.

The great merit of I.P. Pavlov is that he extended the doctrine of reflex to the entire nervous system, starting from the lowest sections and ending with its highest sections, and experimentally proved the reflex nature of all forms of vital activity of the body without exception.

Thanks to reflexes, the body is able to respond in a timely manner to various changes in the environment or internal state and adapt to them. With the help of reflexes, a constant, correct and accurate relationship between parts of the body and the relationship of the whole organism to environmental conditions is established.

List of used literature.

1. Physiology of higher nervous activity and sensory systems: A guide for passing the exam. / Stupina S. B., Filipiechev A. O. - M.: Higher Education, 2008.

2. Physiology of higher nervous activity with the basics of neurobiology: Textbook for students. Biol. Specialties of universities / Shulgovsky V.V. – M.: Publishing Center “Academy”, 2009.

3. Physiology of sensory systems and higher nervous activity: textbook. aid for students higher textbook institutions / Smirnov V.M., Budylina S.M. – 3rd ed., rev. and additional – M.: Publishing Center “Academy”, 2007.

4. Philosophical Dictionary / Ed. I.T. Frolova. - 4th ed. - M.: Politizdat, 2007.

Conditioned reflex- this is an acquired reflex characteristic of an individual (individual). They arise during the life of an individual and are not fixed genetically (not inherited). They appear under certain conditions and disappear in their absence. They are formed on the basis of unconditioned reflexes with the participation of higher parts of the brain. Conditioned reflex reactions depend on past experience, on the specific conditions in which the conditioned reflex is formed.

The study of conditioned reflexes is associated primarily with the name of I. P. Pavlov and the students of his school. They showed that a new conditioned stimulus can trigger a reflex response if it is presented for some time together with an unconditioned stimulus. For example, if a dog is allowed to sniff meat, then gastric juice is released (this is an unconditioned reflex). If, simultaneously with the appearance of meat, a bell rings, then the dog’s nervous system associates this sound with food, and gastric juice will be released in response to the bell, even if the meat is not presented. This phenomenon was discovered independently by Edwin Twitmeier at approximately the same time as in the laboratory of I. P. Pavlov. Conditioned reflexes are the basis acquired behavior. These are the simplest programs. The world around us is constantly changing, so only those who quickly and expediently respond to these changes can live successfully in it. As we gain life experience, a system of conditioned reflex connections develops in the cerebral cortex. Such a system is called dynamic stereotype. It underlies many habits and skills. For example, having learned to skate or bicycle, we subsequently no longer think about how we should move so as not to fall.

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Human Anatomy: Conditioned Reflexes

Conditioned reflexes

Higher nervous activity

Subtitles

Formation of a conditioned reflex

To do this you need:

• The presence of 2 stimuli: an unconditioned stimulus and an indifferent (neutral) stimulus, which then becomes a conditioned signal;
• Certain strength of stimuli. The unconditioned stimulus must be so strong as to cause dominant excitation in the central nervous system. The indifferent stimulus must be familiar so as not to cause a pronounced orienting reflex.
• A repeated combination of stimuli over time, with the indifferent stimulus acting first, then the unconditioned stimulus. Subsequently, the action of the two stimuli continues and ends simultaneously. A conditioned reflex will occur if an indifferent stimulus becomes a conditioned stimulus, that is, it signals the action of an unconditioned stimulus.
• Constancy of the environment - the development of a conditioned reflex requires constancy of the properties of the conditioned signal.

The mechanism of formation of conditioned reflexes

At action of an indifferent stimulus excitation occurs in the corresponding receptors, and impulses from them enter the brain section of the analyzer. When exposed to an unconditioned stimulus, specific excitation of the corresponding receptors occurs, and impulses through the subcortical centers go to the cerebral cortex (cortical representation of the center of the unconditioned reflex, which is the dominant focus). Thus, two foci of excitation simultaneously arise in the cerebral cortex: In the cerebral cortex, a temporary reflex connection is formed between two foci of excitation according to the dominant principle. When a temporary connection occurs, the isolated action of a conditioned stimulus causes an unconditioned reaction. In accordance with Pavlov's theory, the consolidation of temporary reflex communication occurs at the level of the cerebral cortex, and it is based on the principle of dominance.

Types of conditioned reflexes

There are many classifications of conditioned reflexes:

• If the classification is based on unconditioned reflexes, then we distinguish between food, protective, orientation, etc.
• If the classification is based on the receptors on which the stimuli act, exteroceptive, interoceptive and proprioceptive conditioned reflexes are distinguished.
• Depending on the structure of the used conditioned stimulus, simple and complex (complex) conditioned reflexes are distinguished.
  In real conditions of the functioning of the body, as a rule, the conditioned signals are not individual, single stimuli, but their temporal and spatial complexes. And then the conditioned stimulus is a complex of environmental signals.
• There are conditioned reflexes of the first, second, third, etc. order. When a conditioned stimulus is reinforced by an unconditioned one, a first-order conditioned reflex is formed. A second-order conditioned reflex is formed if a conditioned stimulus is reinforced by a conditioned stimulus to which a conditioned reflex was previously developed.
• Natural reflexes are formed in response to stimuli that are natural, accompanying properties of the unconditional stimulus on the basis of which they are developed. Natural conditioned reflexes, compared to artificial ones, are easier to form and more durable.

Notes

Ivan Petrovich Pavlov's school conducted vivisector experiments not only on dogs, but also on people. Street children aged 6–15 years were used as laboratory material. These were tough experiments, but they were the ones that made it possible to understand the nature of human thinking. These experiments were carried out in the children's clinic of the 1st LMI, in the Filatov hospital, in the hospital named after. Rauchfus, in the Department of Experimental Pediatrics of the IEM, as well as in several orphanages. are essential information. In two works by N. I. Krasnogorsky, “Development of the doctrine of the physiological activity of the brain in children” (L., 1939) and “Higher nervous activity of the child” (L., 1958), Professor Mayorov, who was the official chronicler of the Pavlovian school, melancholy noted: “ Some of our employees expanded the range of experimental objects and began studying conditioned reflexes in other animal species; in fish, ascidians, birds, lower apes, as well as children" (F. P. Mayorov, "History of the doctrine of conditioned reflexes." M., 1954). "laboratory material" of a group of Pavlov's students (Prof. N. I. Krasnogorsky , A.G. Ivanov-Smolensky, I. Balakirev, M.M. Koltsova, I. Kanaev) became street children. Full understanding at all levels was ensured by the Cheka.A. A. Yushchenko in his work “Conditional Reflexes of a Child” (1928 All this is confirmed by protocols, photographs and the documentary “Mechanics of the Brain” (another title is “Behavior of Animals and Humans”; directed by V. Pudovkin, camera by A. Golovnya, production film factory "Mezhrabprom-Rus", 1926)