The concept of a reflex is unconditioned and conditioned reflexes. Congenital and acquired forms of behavior

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Methodology for applying unconditioned reflexes

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

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

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

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

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

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

Composition and localization of unconditioned reflexes

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

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

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

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

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

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

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

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

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

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

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

Development of unconditioned reflexes in the embryonic period

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

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

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

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

Phylogenetic development of unconditioned reflexes

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

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

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

Our nervous system is a complex mechanism for the interaction of neurons that send impulses to the brain, and it, in turn, controls all organs and ensures their work. This process of interaction is possible due to the presence in a person of the main inseparable acquired and innate forms of adaptation - conditional and unconditional reactions. A reflex is a conscious response of the body to certain conditions or stimuli. Such well-coordinated work of nerve endings helps us interact with the outside world. A person is born with a set of simple skills - this is called An example of such behavior: the ability of an infant to suck on its mother's breast, swallow food, blink.

and animal

As soon as a living being is born, he needs certain skills that will help ensure his life. The body actively adapts to the surrounding world, that is, it develops a whole range of purposeful motor skills. This mechanism 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 the behavior itself is distinguished by the method of its implementation and application in life: congenital and acquired forms.

Unconditioned reflexes

Scientists say that an innate form of behavior is an unconditioned reflex. An example of such manifestations has been observed since the birth of a person: sneezing, coughing, swallowing saliva, blinking. The transfer of such information is carried out by inheritance of the parent program by centers that are responsible for reactions to stimuli. These centers are located in the brain stem or spinal cord. Unconditioned reflexes help a person 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 around them, but all mammals, including humans, have a sucking skill. If you attach an infant or a young animal to the mother's nipple, a reaction will immediately occur in the brain and the feeding process will begin. This is the unconditioned reflex. Examples of eating behavior are inherited in all creatures that receive nutrients from mother's milk.

Defense reactions

These types of reactions to external stimuli are inherited and are called natural instincts. Evolution has laid in us the need to protect ourselves and take care of our safety in order to survive. Therefore, we have learned to instinctively respond to danger, this is an unconditioned reflex. Example: Have you noticed how the head deviates if someone raises a fist over it? When you touch a hot surface, your hand withdraws. This behavior is also called hardly a person in their right mind will 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 don’t even think about it, the instinct immediately works.

Try to bring your finger to the baby's palm, and he will immediately try to grab it. Such reflexes have been developed over the centuries, however, now such a skill is not really needed by a child. Even among primitive people, the baby clung to the mother, and so she endured him. There are also unconscious innate reactions, which are explained by the connection of several groups of neurons. For example, if you hit the knee with a hammer, it will twitch - an example of a two-neuron reflex. In this case, two neurons come into contact and send a signal to the brain, causing 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 react to external stimuli - this is an unconditioned reflex. Example: the child begins to distinguish the voice of the mother, loud sounds, bright colors. All these factors attract his attention - an indicative skill begins to form. Involuntary attention is the starting point in the formation of the assessment of stimuli: the baby begins to understand that when the mother speaks to him and approaches him, most likely she will take him in her arms or feed him. That is, a person forms a complex form of behavior. His crying will draw attention to him, and he uses this reaction consciously.

sexual reflex

But this reflex belongs to the unconscious and unconditioned, 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 inherently human, they are launched in a certain order.

Conditioned reflexes

In addition to the instinctive reactions that we have at birth, a person needs many other skills in order to better adapt to the world around him. Acquired behavior is formed both in animals and in humans throughout life, this phenomenon is called "conditioned reflexes". Examples: at the sight of food, salivation occurs, while observing the diet, there is a feeling of hunger at a certain time of the day. Such a 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 certain action. Visual images, sounds, smells are able to form stable connections and give rise to new reflexes. When someone sees a lemon, salivation may begin, and with a sharp smell or contemplation of an unpleasant picture, nausea occurs - 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 responses can come and go. Everything depends on For example, in childhood, a child reacts to the sight of a bottle of milk, realizing that this 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 conditional reactions affect only the complex behavior of a person, but are not transmitted to descendants. Each organism "adjusts" 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 the product. Conditioned stimuli change constantly depending on our preferences and age: in childhood, at the sight of a toy, the baby experiences joyful emotions; in the process of growing up, for example, visual images of a film evoke a reaction.

Animal reactions

Animals, like humans, have both unconditioned innate reactions and acquired reflexes throughout their lives. In addition to the instinct of self-preservation and the production of food, living beings also adapt to the environment. They develop a reaction to the nickname (pets), 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 at each feeding you call the dog with a bell or a certain signal, he will have a strong perception of the situation, and he will immediately react. In the process of training, rewarding a pet for a completed command with a favorite treat forms a conditioned response, walking a dog and the type of leash signals an imminent walk where he should relieve himself are examples of reflexes in animals.

Summary

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

The main activity of the nervous system is reflex. All reflexes are usually divided into unconditional and conditional.

Unconditioned reflexes	Conditioned reflexes
1. congenital, genetically programmed reactions of the body, characteristic of all animals and humans. 2. The reflex arcs of these reflexes are formed in the process prenatal development, and sometimes postnatal period. Ex: congenital sexual reflexes are finally formed in a person only by 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 not necessary. 3. Are species-specific, i.e. formed in the process of evolution and are characteristic of all representatives of this species. 4. Relatively constant and persist throughout the life of the organism. 5. Arise on specific(adequate) stimulus for each reflex. 6. Reflex centers are at the level spinal cord and in brain stem	1. Acquired reactions of higher animals and humans developed as a result of learning (experience). 2. Reflex arcs are formed in the process postnatal development. They are characterized by high mobility, 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 from life experience. 4. fickle and depending on certain conditions, they can be developed, consolidated or fade away. 5. May form on any irritant perceived by the body 6. Reflex centers are located in cerebral cortex
Example: food, sexual, defensive, indicative.	Example: salivation for the smell of food, precise movements when writing, playing musical instruments.
Meaning: help survival, it is "the application of the experience of ancestors in practice"	Meaning: help to adapt to changing environmental conditions.

Classification of unconditioned reflexes.

The question of classifying unconditioned reflexes is still 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 pulling the hand with painful irritation of the finger.

3. Orienting reflexes, or reflexes "What is it?", as IP Pavlov called them. A new and unexpected stimulus draws attention, such as turning the head towards an unexpected sound. A similar reaction to novelty, which has an important adaptive value, is also observed in various animals. It is expressed in alertness and listening, sniffing and examining new objects.

4.Game reflexes. For example, children's games in the family, hospital, etc., during which children create models of possible life situations and carry out a kind of "preparation" for various life surprises. The unconditioned reflex play activity of the child quickly acquires a rich "spectrum" of conditioned reflexes, and therefore the game 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 provide 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 is still 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

To understand the nervous mechanisms of conditioned reflexes, consider such a simple conditioned reflex reaction as increased salivation in a person at the sight of a lemon. This natural conditioned reflex. In a person who has never tried a lemon, this object does not cause any reactions, except for curiosity (orienting reflex). What physiological connection exists between such functionally distant organs as the eyes and salivary glands? I.P. dealt with this issue. Pavlov.

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

The excitation that occurs in the visual receptors at the sight of a lemon, through the centripetal fibers, enters the visual section of the cerebral cortex (occipital region) and causes excitation cortical neurons- arises focus of excitation.

2. If after this a person gets the opportunity to taste a lemon, then a focus of excitation 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 of lemon), the food focus of excitation has a dominant (main) value and “attracts” excitation from the visual center.

4. Between two previously unconnected nerve centers arises nervous temporal connection, i.e. a kind of temporary "pontoon bridge" connecting the two "shores".

5. Now the excitation that occurs in the visual center quickly “passes” along the “bridge” of the temporary connection to the food center, and from there along the efferent nerve fibers to the 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 unconditioned reinforcement.

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

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

4. Repetition.

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

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

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

The development of conditioned reflexes with such unconditional reinforcement is the fastest. In other words, powerful factors contributing to the formation of conditioned reflex activity are rewards and punishments.

Classifications of conditioned reflexes

Due to their large number, it is difficult.

According to the location of the receptor:

1. exteroceptive- conditioned reflexes formed during stimulation of exteroceptors;

2. interoceptive - reflexes that form when stimulating receptors located in internal organs;

3. proprioceptive, arising from stimulation of muscle receptors.

According to the nature of the receptor:

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

2. artificial- under the action of indifferent stimuli. For example, the secretion of saliva in a child at the sight of favorite sweets is a natural conditioned reflex (the secretion of saliva when the mouth is irritated by some food is an unconditioned reflex), and the secretion of saliva that occurs in a hungry child at the sight of dinner utensils 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 brake.

By the nature of the response:

1. motor;

2. vegetative are formed from the internal organs - the heart, lungs, etc. Impulses from them, penetrating into the cerebral cortex, immediately slow down, not reaching our consciousness, because of 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, with food intake. That is why, by the time of eating, the functional activity of the digestive organs increases, which has a biological meaning. Reflexes for a while belong to the group of so-called trace conditioned reflexes. These reflexes are developed if the unconditioned reinforcement is given 10 to 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. Orbeli are also a kind of conditioned reflexes. 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 front of another, then the “spectator” also forms the corresponding temporary connections. In children, imitative reflexes play an 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 anticipate favorable or unfavorable situations for life.

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

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

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

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

Conditioned reflexes

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

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

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

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

A necessary condition for the development of conditioned reflexes is:

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

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

An example of the development of a conditioned reflex

Classification of conditioned reflexes:

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

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

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

Exteroceptive- irritation is perceived by body receptors, dominated by reflex reactions (gustatory, tactile);
intraceptive- are 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 arise under the action of a stimulus that has no connection with an unconditioned stimulus (sound signals, light stimulation).

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

Unconditioned reflexes

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

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

Unconditioned reflexes are characterized by the following features:

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

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

Classification of unconditioned reflexes

Congenital reactions are classified into:

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

Classification of unconditioned reflexes according to Pavlov

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

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

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

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

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

Statokinetic provide bipedalism, balance, movement of the body.

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

Classification of unconditioned reflexes according to Simonov

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

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

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

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

Table comparing conditioned and unconditioned reflexes

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

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

Braking

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

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

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

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

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

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

The meaning of conditioned and unconditioned reflexes

Unconditioned reflex activity is necessary for the survival and preservation of the species. A good example is the birth of a child. In the new world for him, many dangers await him. Due to the presence of innate reactions, the cub can survive in these conditions. 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 protective reactions).

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

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

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

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

What are unconditioned reflexes?

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

What reflexes are unconditioned?

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

What are conditioned reflexes?

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

An independent category of conditioned reflexes

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

Compare unconditioned and conditioned reflexes

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

Scheme of the unconditioned reflex

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

Features of unconditioned reflexes

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

Unconditional instinct and animal reflex

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

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

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

Species specificity

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

Unconditional braking

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

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