Where conditioned and unconditioned reflexes close. Conditioned and unconditioned reflexes - classification and types

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The main form of activity of the nervous system is reflex. All reflexes are usually divided into unconditioned and conditioned.

Unconditioned reflexes	Conditioned reflexes
1. Congenital, genetically programmed reactions of the body, characteristic of all animals and humans. 2. Reflex arcs of these reflexes are formed in the process prenatal development, sometimes in postnatal period. Ex: sexual innate reflexes are finally formed in a person only at the time of puberty in adolescence. They have little changing reflex arcs passing through the subcortical sections of the central nervous system. The participation of the cortex in the course of many unconditioned reflexes is optional. 3. Are species-specific, i.e. formed in the process of evolution and are characteristic of all representatives of this species. 4. Regarding permanent and persist throughout the life of the organism. 5. Occur on specific(adequate) stimulus for each reflex. 6. Reflex centers are at the level spinal cord and in brain stem	1. Purchased reactions of higher animals and humans developed as a result of learning (experience). 2. Reflex arcs are formed during the process postnatal development. They are characterized by high mobility and the ability to change under the influence of environmental factors. Reflex arcs of conditioned reflexes pass through the highest part of the brain - the cerebral cortex. 3. Are individual, i.e. arise on the basis of life experience. 4. Fickle and, depending on certain conditions, they can be developed, consolidated or fade away. 5. Can form on any stimulus perceived by the body 6. Reflex centers are located in cerebral cortex
Example: food, sexual, defensive, indicative.	Example: salivation to the smell of food, precise movements when writing, playing musical instruments.
Meaning: help survival, this is “putting the experience of ancestors into practice”	Meaning: help adapt to changing environmental conditions.

Classification of unconditioned reflexes.

The question of the classification of unconditioned reflexes still remains open, although the main types of these reactions are well known.

1. Food reflexes. For example, salivation when food enters the oral cavity or the sucking reflex in a newborn baby.

2. Defensive reflexes. Protect the body from various adverse effects. For example, the reflex of withdrawing a hand when a finger is painfully irritated.

3. Approximate reflexes, or “What is it?” reflexes, as I. P. Pavlov called them. A new and unexpected stimulus attracts attention, for example, turning the head towards an unexpected sound. A similar reaction to novelty, which has important adaptive significance, is observed in various animals. It is expressed in alertness and listening, sniffing and examining new objects.

4.Gaming reflexes. For example, children's games of family, hospital, etc., during which children create models of possible life situations and carry out a kind of “preparation” for various life surprises. The unconditional reflex play activity of a child quickly acquires a rich “spectrum” of conditioned reflexes, and therefore play is the most important mechanism for the formation of the child’s psyche.

5.Sexual reflexes.

6. Parental reflexes are associated with the birth and feeding of offspring.

7. Reflexes that ensure movement and balance of the body in space.

8. Reflexes that support constancy of the internal environment of the body.

Complex unconditioned reflexes I.P. Pavlov called instincts, the biological nature of which remains unclear in its details. In a simplified form, instincts can be represented as a complex interconnected series of simple innate reflexes.

Physiological mechanisms of formation of conditioned reflexes

For understanding nervous mechanisms conditioned reflexes, let's consider such a simple conditioned reflex reaction as increased salivation in a person when he sees a lemon. This natural conditioned reflex. In a person who has never tasted lemon, this object does not cause any reactions other than curiosity (indicative reflex). What physiological connection exists between such functionally distant organs as the eyes and salivary glands? This issue was resolved by I.P. Pavlov.

The connection between the nerve centers that regulate the processes of salivation and analyze visual stimulation arises as follows:

The excitation that occurs in the visual receptors at the sight of a lemon travels along centripetal fibers to the visual cortex of the cerebral hemispheres (occipital region) and causes excitation cortical neurons- arises source of excitation.

2. If after this a person gets the opportunity to taste the lemon, then a source of excitement arises in the subcortical nerve center salivation and in its cortical representation, located in the frontal lobes of the cerebral hemispheres (cortical food center).

3. Due to the fact that the unconditioned stimulus (the taste of lemon) is stronger than the conditioned stimulus ( external signs lemon), the food focus of excitation has a dominant (main) significance and “attracts” excitation from the visual center.

4. Between two previously unconnected nerve centers, a neural temporal connection, i.e. a kind of temporary “pontoon bridge” connecting two “shores”.

5. Now the excitation arising in the visual center quickly “travels” along the “bridge” of temporary communication to the food center, and from there along the efferent nerve fibers to salivary glands, causing salivation.

Thus, for the formation of a conditioned reflex, the following are necessary: conditions:

1. The presence of a conditioned stimulus and unconditional reinforcement.

2. The conditioned stimulus must always somewhat precede the unconditional reinforcement.

3. The conditioned stimulus, in terms of the strength of its impact, must be weaker than the unconditioned stimulus (reinforcement).

4. Repetition.

5. A normal (active) functional state of the nervous system is necessary, first of all its leading part - the brain, i.e. the cerebral cortex should be in a state of normal excitability and performance.

Conditioned reflexes formed by combining a conditioned signal with unconditioned reinforcement are called first order reflexes. If the reflex is developed, then it can also become the basis of a new conditioned reflex. It is called second order reflex. Reflexes developed on them - third order reflexes etc. In humans, they are formed on verbal signals, reinforced by the results of joint activities of people.

A conditioned stimulus can be any change in the environmental and internal environment of the body; bell, electric light, tactile skin stimulation, etc. Food reinforcement and pain stimulation are used as unconditioned stimuli (reinforcers).

The development of conditioned reflexes with such unconditional reinforcement occurs most quickly. In other words, powerful factors contributing to the formation of conditioned reflex activity are reward and punishment.

Classifications of conditioned reflexes

Due to their large number, it is difficult.

According to the location of the receptor:

1. exteroceptive- conditioned reflexes formed when exteroceptors are stimulated;

2. interoceptive - reflexes formed by irritation of receptors located in internal organs;

3. proprioceptive, arising from irritation of muscle receptors.

By the nature of the receptor:

1. natural- conditioned reflexes formed by the action of natural unconditioned stimuli on receptors;

2. artificial- under the influence of indifferent stimuli. For example, the release of saliva in a child at the sight of his favorite sweets is a natural conditioned reflex (the release of saliva when the oral cavity is irritated by some food is an unconditioned reflex), and the release of saliva that occurs in a hungry child at the sight of dinnerware is an artificial reflex.

By action sign:

1. If the manifestation of a conditioned reflex is associated with motor or secretory reactions, then such reflexes are called positive.

2. Conditioned reflexes without external motor and secretory effects are called negative or braking.

By the nature of the response:

1. motor;

2. vegetative are formed from internal organs - heart, lungs, etc. Impulses from them, penetrating the cerebral cortex, are immediately inhibited, not reaching our consciousness, due to this we do not feel their location in a state of health. And in case of illness, we know exactly where the diseased organ is located.

Reflexes occupy a special place for a while, the formation of which is associated with regularly repeated stimuli at the same time, for example, food intake. That is why, by the time of eating, the functional activity of the digestive organs increases, which has a biological meaning. Temporary reflexes belong to the group of so-called trace conditioned reflexes. These reflexes are developed if unconditional reinforcement is given 10 - 20 seconds after the final action of the conditioned stimulus. In some cases, it is possible to develop trace reflexes even after a 1-2 minute pause.

Reflexes are important imitation, which, according to L.A. Orbels are also a type of conditioned reflex. To develop them, it is enough to be a “spectator” of the experiment. For example, if you develop some kind of conditioned reflex in one person in full view of another, then the “viewer” also forms corresponding temporary connections. In children, imitative reflexes play important role in the formation of motor skills, speech and social behavior, in adults in the acquisition of labor skills.

There are also extrapolation reflexes - the ability of humans and animals to foresee situations that are favorable or unfavorable for life.

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

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

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 irritations.

Conditioned reflexes

Conditioned reflexes are formed on the basis of unconditional ones, 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 impulses to 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 rear horns spinal cord, where it is located interneuron. 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 catch reflex must be inferior in strength to the biologically significant effect;
• normal functioning of the cerebral cortex and the absence of distractions are mandatory.

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

An example of developing 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 first order reflex.
2. Based on the classical acquired reflex of the first order, it is developed second order reflex.

Thus, a third-order defensive reflex was formed in dogs, the fourth could not be developed, and the digestive reflex 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 and predominates among reflex reactions (taste, tactile);
• intraceptive– caused by 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 occur under the influence of stimulation that has no connection with the unconditioned stimulus (sound signals, light stimulation).

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

Unconditioned reflexes

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

Reflex arcs hereditary reactions are laid down before a person is born. 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 appear (sexually) after a certain period of time.

Unconditioned reflexes are characterized by the following features:

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

Unconditioned reflexes are needed to fulfill the needs of the body; they are constant, but as a result of illnesses or bad habits they can disappear. So, when the iris of the eye is diseased, 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 the hot object);
• complex(maintaining homeostasis in situations of increased CO 2 concentration in the blood by increasing the frequency of respiratory movements);
• the most complex(instinctive behavior).

Classification of unconditioned reflexes according to Pavlov

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

TO food This includes the secretion of saliva at the sight of food and its entry into the digestive tract, the secretion of hydrochloric acid, gastrointestinal motility, sucking, swallowing, chewing.

Protective accompanied by contraction of muscle fibers in response to irritant. Everyone is familiar with the situation when a hand reflexively withdraws from a hot iron or a sharp knife, sneezing, coughing, watery eyes.

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

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

Statokinetic provide upright posture, balance, and body movement.

Homeostatic– independent regulation blood pressure, vascular tone, respiratory rate, heart rate.

Classification of unconditioned reflexes according to Simonov

Vital to maintain life (sleep, nutrition, saving energy) depend only on the individual.

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

The need for self-development(desire for individual growth, to discover new things).

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

Comparison table between conditioned and unconditioned reflexes

Comparison of the characteristics of conditioned (acquired) and unconditioned (innate) reflexes
Unconditional	Conditional
Congenital	Acquired during life
Present in all representatives of the species	Individual for each organism
Relatively constant	Appear and disappear with changes in the external environment
Formed at the level of the spinal cord and medulla oblongata	Carried out through the work of the brain
Laid in utero	Developed against the background of innate reflexes
Occurs when a stimulus acts on certain receptor areas	Manifest under the influence of any stimulus that is perceived by the individual

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

Braking

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

When the organism under study is exposed to several stimuli at the same time (light, sound, smell), the conditioned reflex fades, but over time the indicative reflex is activated and the inhibition disappears. This type of braking is called temporary.

Conditioned inhibition(acquired) does not arise on its own, it must be developed. There are 4 types of conditioned inhibition:

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

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

Example of external inhibition (dog's reaction 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. A good example serves the birth of a child. In a new world for him, many dangers await him. Thanks to the presence of innate reactions, the cub can survive in these conditions. Immediately after birth, the respiratory system is activated, the sucking reflex provides nutrients, touching sharp and hot objects is accompanied by an instant withdrawal of the hand (manifestation of defensive reactions).

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

The presence of conditioned reflexes in animals gives them the ability to quickly respond to the voice of a predator and save their lives. When a person sees food, he performs conditioned reflex activity, salivation begins, production gastric juice for quick digestion of food. The sight and smell of some objects, on the contrary, signals danger: the red cap of the fly agaric, the smell of spoiled food.

The meaning of conditioned reflexes in Everyday life humans and animals are huge. Reflexes help you navigate the terrain, get food, and escape from danger while saving your life.

Our nervous system is complex mechanism the interactions of neurons that send impulses to the brain, and it, in turn, controls all organs and ensures their functioning. This process of interaction is possible due to the presence in humans of basic, inseparable acquired and innate forms of adaptation - conditioned and unconditioned reactions. A reflex is a conscious response of the body to certain conditions or stimuli. Such coordinated work of nerve endings helps us interact with the world around us. A person is born with a set of simple skills - this is called an example of such behavior: the ability of a baby to suckle at the mother's breast, swallow food, blink.

and animal

As soon as a living creature is born, it needs certain skills that will help ensure its life. The body actively adapts to the surrounding world, that is, it develops a whole complex of targeted motor skills. It is this mechanism that is called species behavior. Each living organism has its own set of reactions and innate reflexes, which is inherited and does not change throughout life. But behavior itself is distinguished by the method of its implementation and application in life: congenital and acquired forms.

Unconditioned reflexes

Scientists say that the innate form of behavior is an unconditioned reflex. An example of such manifestations is observed from the moment a person is born: sneezing, coughing, swallowing saliva, blinking. The transfer of such information is carried out by inheriting the parent program by the centers that are responsible for reactions to stimuli. These centers are located in the brainstem or in spinal cord. Unconditioned reflexes help a person to quickly and accurately respond to changes in the external environment and homeostasis. Such reactions have a clear demarcation depending on biological needs.

• Food.
• Approximate.
• Protective.
• Sexual

Depending on the species, living beings have different reactions to the world, but all mammals, including humans, have a sucking habit. If you put a baby or young animal on the mother's nipple, a reaction will immediately occur in the brain and the feeding process will begin. This is an unconditioned reflex. Examples eating behavior are inherited by all creatures that receive nutrients with mother's milk.

Defensive reactions

These types of reactions to external stimuli are inherited and are called natural instincts. Evolution has given us the need to protect ourselves and take care of our safety in order to survive. Therefore, we have learned to instinctively react to danger; this is an unconditioned reflex. Example: Have you ever noticed how your head tilts when someone raises a fist over it? When you touch a hot surface, your hand jerks back. This behavior is also called unlikely that a person in his right mind would try to jump from a height or eat unfamiliar berries in the forest. The brain immediately starts the process of processing information that will make it clear whether it is worth risking your life. And even if it seems to you that you are not thinking about it, instinct immediately kicks in.

Try to bring your finger to the baby’s palm, and he will immediately try to grab it. Such reflexes have been developed over centuries, however, now a child does not really need such a skill. Even among primitive people, the baby clung to the mother, and that’s how she carried him. There are also unconscious innate reactions that are explained by the connection of several groups of neurons. For example, if you hit your knee with a hammer, it will jerk - an example of a two-neuron reflex. In this case, two neurons come into contact and send a signal to the brain, forcing it to respond to an external stimulus.

Delayed reactions

However, not all unconditioned reflexes appear immediately after birth. Some arise as needed. For example, a newborn baby practically does not know how to navigate in space, but after about a couple of weeks he begins to respond to external stimuli - this is an unconditioned reflex. Example: a child begins to distinguish the mother’s voice, loud sounds, bright colors. All these factors attract his attention - an orientation skill begins to form. Involuntary attention is the starting point in the formation of an assessment of stimuli: the baby begins to understand that when the mother speaks to him and approaches him, most likely she will pick him up or feed him. That is, a person forms a complex form of behavior. His crying will attract attention to him, and he consciously uses this reaction.

Sexual reflex

But this reflex is unconscious and unconditional, it is aimed at procreation. It occurs during puberty, that is, only when the body is ready for procreation. Scientists say that this reflex is one of the strongest, it determines the complex behavior of a living organism and subsequently triggers the instinct to protect its offspring. Despite the fact that all these reactions are initially characteristic of humans, they are triggered in a certain order.

Conditioned reflexes

In addition to the instinctive reactions that we have at birth, a person needs many other skills to better adapt to the world around him. Acquired behavior is formed in both animals and people throughout life; this phenomenon is called “conditioned reflexes”. Examples: when you see food, salivation occurs; when you follow a diet, you feel hungry at a certain time of the day. This phenomenon is formed by a temporary connection between the center or vision) and the center of the unconditioned reflex. An external stimulus becomes a signal for a specific action. Visual images, sounds, smells can form lasting connections and give rise to new reflexes. When someone sees a lemon, salivation may begin, and when a strong smell or contemplation of an unpleasant picture occurs, nausea may occur - these are examples of conditioned reflexes in humans. Note that these reactions can be individual for each living organism; temporary connections are formed in the cerebral cortex and send a signal when an external stimulus occurs.

Throughout life, conditioned reactions can arise and also disappear. It all depends on For example, in childhood a child reacts to the sight of a bottle of milk, realizing that it is food. But when the baby grows up, this object will not form an image of food for him; he will react to a spoon and a plate.

Heredity

As we have already found out, unconditioned reflexes are inherited in every species of living beings. But conditioned reactions only affect complex human behavior, but are not passed on to descendants. Each organism “adapts” to a particular situation and the reality surrounding it. Examples of innate reflexes that do not disappear throughout life: eating, swallowing, reaction to the taste of a product. Conditioned stimuli change constantly depending on our preferences and age: in childhood, when a child sees a toy, he experiences joyful emotions; in the process of growing up, a reaction is caused by, for example, visual images films.

Animal reactions

Animals, like humans, have both unconditioned innate reactions and acquired reflexes throughout life. In addition to the instinct of self-preservation and obtaining food, living beings also adapt to their environment. They develop a reaction to the nickname (pets), and with repeated repetition, an attention reflex appears.

Numerous experiments have shown that it is possible to instill in a pet many reactions to external stimuli. For example, if you call your dog with a bell or a certain signal at each feeding, he will have a strong perception of the situation and he will immediately react. During the training process, rewarding a pet for following a command with a favorite treat forms a conditioned reaction; walking the dog and the sight of a leash signals an imminent walk, where he must relieve himself - examples of reflexes in animals.

Summary

The nervous system constantly sends many signals to our brain, and they shape the behavior of humans and animals. The constant activity of neurons allows us to perform habitual actions and respond to external stimuli, helping us better adapt to the world around us.

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 the body’s assistants, allowing it to quickly respond to any changes and adapt to them.

Story

The idea of ​​a conditioned reflex was first 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; the entire nervous system is involved in its work. This allows the body to maintain a connection with the environment.

Studied by 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. The treatise became 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 the unconditional type are characteristic of each type of living organism. They are called instincts. Some of them are quite complex. An example of this would be bees making honeycombs or birds making nests. Thanks to the presence of instincts, the body is able to optimally adapt to environmental conditions.

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

As for monkeys and humans, 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 unconditioned reflexes, and some of them simply disappear.

Classification of instincts

Unconditioned reflexes are very strong. Only under certain conditions, when their manifestation becomes unnecessary, can they disappear. For example, the canary, domesticated about three hundred years ago, currently does not have the instinct to build nests. The following types of unconditioned reflexes are distinguished:

Which is the body's reaction to a variety of physical or chemical stimuli. Such reflexes, in turn, can manifest locally (withdrawal of the hand) or be 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 it.
- Parental and sexual instincts associated with the maintenance and reproduction of the species.

A comfortable instinct that serves to keep the body clean (bathing, scratching, shaking, etc.).
- Orienting instinct, when the eyes and head are turned towards the stimulus. This reflex is necessary to preserve life.
- The instinct of freedom, which is especially clearly expressed 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

During life, acquired reactions of the body 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, consolidated, and 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 will remain.

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

Examples

For the body’s reaction to occur, such as the release of saliva when knives and forks clink, as well as when an animal’s feeding cup is knocked (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 turning on of a light bulb will cause the dog's paw to flex if these phenomena have repeatedly occurred accompanied by electrical stimulation of the animal's leg, as a result of which an unconditioned type of flexion reflex appears.

The conditioned reflex is the child's hands being pulled away from the fire and subsequent crying. However, these phenomena will only occur if the type of fire, even once, coincides with a burn.

Reaction components

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

Conditioned reactions usually reproduce the structure of unconditioned ones. This occurs due to the stimulation of the same nerve centers by stimuli.

Classification of conditioned reflexes

The responses acquired by the body to various stimuli are divided into types. Some of the existing classifications have great value when 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 rapid production and great durability. Natural reflexes, even in the absence of subsequent reinforcement, can be maintained throughout life. The importance of the conditioned reflex is especially great in the very first stages of the organism’s life, when it adapts to 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 precisely such 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 increasing lighting, etc.

First and highest order

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

For example, irritation in the form of a bell 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 influence 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 body, then the reactions are classified as negative. For the process of adaptation to constantly changing environmental conditions, both one and the second species are of great importance.

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

Education mechanism

Conditioned reflexes occur 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 a conditioned stimulus is somewhat ahead of the action of instinct;
- the conditioned stimulus is necessarily reinforced by the influence of the unconditional;
- the body must be awake and healthy;
- the condition of the absence of extraneous stimuli producing a distracting effect is met.

The centers of conditioned reflexes located in the cerebral cortex establish a temporary connection (closure) with each other. In this case, the irritation is perceived by cortical neurons, which are part of the unconditioned reflex arc.

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. An action in the opposite direction will be required. This 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 unconditional. It appears as a response to the action of some extraneous stimulus. There is also internal inhibition. It is called conditional.

External braking

This reaction received this name due to the fact that its development is facilitated by processes taking place in those areas of the cortex that do not participate in reflex activity. For example, an extraneous smell, sound, or change in lighting before the onset of the food reflex can reduce it or contribute to its complete disappearance. A new stimulus acts as an inhibitor for a conditioned response.

Eating reflexes can also be eliminated by painful stimuli. Inhibition of the body's reaction is facilitated by bladder overflow, vomiting, internal inflammatory processes etc. All of them suppress food reflexes.

Internal inhibition

It occurs when the received signal is not reinforced by an unconditioned stimulus. Internal inhibition of conditioned reflexes occurs if, for example, an animal is periodically turned on an electric light bulb in front of its eyes during the day without bringing food. It has been experimentally proven that saliva production will decrease each time. As a result, the reaction will fade away completely. However, the reflex will not disappear without a trace. He will simply slow 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 body’s reaction to this stimulus will subsequently disappear forever.

Types of internal braking

Several types of elimination of the body's reaction to stimuli are classified. Thus, the basis for the disappearance of conditioned reflexes, which are simply not needed under given specific conditions, is extinctive inhibition. There is another type of this phenomenon. This is discriminative or differentiated inhibition. Thus, an animal can distinguish the number of metronome beats at which food will be brought to it. This happens when this conditioned reflex is previously developed. The animal distinguishes between stimuli. The basis of this reaction is internal inhibition.

The value of eliminating reactions

Conditioned inhibition plays a significant role in the life of the body. Thanks to it, the process of adaptation to the environment occurs 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 signaling value. For example, an animal, knowing in advance that danger is approaching, organizes its behavior in a certain way.

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

The basic principles and patterns manifested in the formation of not only complex but also elementary reactions are the same for all living organisms. From this follows an important conclusion for philosophy and the natural sciences that something cannot but obey the general laws of biology. In this regard, it can be studied objectively. However, it is worth keeping in mind that activities human brain has qualitative specificity and a fundamental difference from the work of the animal’s brain.