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

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

I.P. Pavlov showed that all reflex reactions can be divided into two groups: unconditional and conditional. Unconditioned reflexes can be simple or complex. Complex innate unconditional reflex reactions are called instincts.

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

Conditioned reflex is an adaptive activity carried out by the higher parts of the central nervous system through the formation of temporary connections between the signal stimulus and the signaled

Table. Comparative characteristics of unconditioned and conditioned reflexes.

General signs of conditioned reflexes

Conditioned reflex a) is individual higher adaptation to changing living conditions; b) is carried out highest departments of the central nervous system; V) purchased through temporary nerve connections and is lost, if the environmental conditions that caused it have changed; d) represents warning signal reaction.

The physiological basis for the emergence of conditioned reflexes is the formation of functional temporary connections in the higher parts of the central nervous system. A temporary connection is a set of neurophysiological, biochemical and ultrastructural changes in the brain that arise during the combined action of conditioned and unconditioned stimuli. I.P. Pavlov suggested that during the development of a conditioned reflex, a temporary nervous connection is formed between two groups of cortical cells - the cortical representations of the conditioned and unconditioned reflexes. Excitation from the center of the conditioned reflex can be transmitted to the center of the unconditioned reflex from neuron to neuron.

The Figure shows a diagram of the Formation of a conditioned salivary (food reinforcement) reflex to light (conditioned signal).

Topic 22. Characteristics and properties of conditioned reflexes

One of the main elementary acts of higher nervous activity is the conditioned reflex.

The idea of ​​conditioned reflex activity is inextricably linked with the name of Ivan Petrovich Pavlov, who at the beginning of the last century discovered and studied the mechanisms of formation of a conditioned reflex. Today, in any physiology textbook published in any country in the world, such reflexes are called classical or Pavlovian. While studying the digestive system of dogs, Pavlov discovered that animals begin to secrete saliva long before receiving food at the mere sight of the servant dressed in a white coat who usually brings it. Continuing his experiments, Pavlov discovered that the sound of a bell or a flash of light preceding the appearance of food could also cause salivation in dogs. Thus, the development of a conditioned reflex occurs when a stimulus that naturally causes a certain reaction (for example, food) is combined several times with some other, previously neutral stimulus (for example, a bell). After this, the neutral stimulus begins to evoke the same reaction. I. P. Pavlov showed that while in the underlying parts of the central nervous system - the subcortical nuclei, brain stem, spinal cord - reflex reactions are carried out along innate, hereditarily fixed nerve pathways, in the cerebral cortex nerve connections are developed and created in the process the individual life of animals and humans, as a result of a combination of countless irritations acting on the body.

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

Differences between conditioned and unconditioned reflexes:

Unconditioned reflexes	Conditioned reflexes
These are innate, hereditary reactions of the body	these are reactions acquired by the body in the process of individual development based on “life experience”
are specific, i.e. characteristic of all representatives of a given species	are individual: some representatives of the same species may have them, while others may not
relatively constant, as a rule, persist throughout life	are unstable and, depending on certain conditions, they can develop, gain a foothold or disappear
carried out in response to adequate stimulation applied to one specific receptive field	can be formed in response to a wide variety of stimuli applied to various receptive fields
closes predominantly at the level of the spinal cord and brainstem	are closed at the level of the cortex. After removal of the cerebral cortex, the developed conditioned reflexes disappear
are carried out through a phylogenetically fixed, anatomically expressed reflex arc.	carried out through functional temporary connections

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

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

Conditioned reflexes are developed on the basis of unconditioned reflexes. The essence of the conditioned reflex activity of the body comes down to the transformation of an indifferent stimulus into a signal, meaningful one, thanks to the repeated reinforcement of the irritation with an unconditioned stimulus. Due to the reinforcement of a conditioned stimulus by an unconditioned stimulus, a previously indifferent stimulus is associated in the life of the organism with a biologically important event and thereby signals the occurrence of this event. In this case, any innervated organ can act as an effector link in the reflex arc of a conditioned reflex. There is no organ in the human or animal body whose functioning could not change under the influence of a conditioned reflex. Any function of the body as a whole or of its individual physiological systems can be modified (strengthened or suppressed) as a result of the formation of a corresponding conditioned reflex.

The general rules for the formation of conditioned reflexes are as follows.

1) The indifferent stimulus should appear a little earlier than the unconditional one. If you turn on the bell or light bulb after feeding, the reflex will not develop. If an indifferent stimulus is used half an hour before feeding, and not a few seconds before it, then nothing will work either.

2) The indifferent stimulus must be weaker than the unconditioned. A powerful spotlight instead of a light bulb or a fire siren instead of a bell can only frighten the animal, while a light bulb or bell initially causes an indicative reflex (“what is this?”), which usually soon disappears due to an addiction reaction. After this, the stimulus becomes indifferent or indifferent. The strength of an unconditioned stimulus can be determined, for example, by a feeling of hunger, and therefore, with a full stomach, digestive conditioned reflexes are poorly formed.

3) It is necessary so that other stimuli do not interfere with the development of conditioned reflexes. It is no coincidence that, by order of Pavlov, special “towers of silence” were built at his institute for conducting experiments, since external stimuli (for example, noise or the arrival of a stranger) can interfere with the manifestation of already developed reflexes and inhibit the formation of new ones.

To develop a conditioned reflex the normal physiological state of the cortical and subcortical structures is also necessary, forming the central representation of the corresponding conditioned and unconditional stimuli, the absence of significant pathological processes in the body.

If the specified conditions are met, a conditioned reflex can be developed to almost any stimulus. Conditioned reflexes can be developed not only with positive, but also with negative types of reinforcement, for example, with pain. So, if you turn on the bell shortly before painful irritation of the dog’s paw with an electric current, it will soon begin to bend this paw just by turning on the bell, which becomes a conditioned stimulus. People also form similar conditioned reflex connections. In this way, in particular, certain emotional reactions, especially fear, can be developed. A child, while he is not yet old enough to understand why doctors and nurses prick him with needles and generally torture him in every possible way against his will, often begins to cry at the sight of a man in a white coat. He learned to associate cold instruments, unpleasant odors, subcutaneous injections with a white coat, and he developed a conditioned reflex - fear - to a previously neutral stimulus (white coat).

The physiological mechanism underlying the conditioned reflex. In the zone of the cortical representation of the conditioned stimulus and the cortical (or subcortical) representation of the unconditioned stimulus, two foci of excitation are formed. The focus of excitation caused by an unconditional stimulus of the external or internal environment of the body, as a stronger (dominant) one, attracts to itself excitation from the focus of weaker excitation caused by the conditioned stimulus. After several repeated presentations of the conditioned and unconditioned stimuli, a stable path of excitation movement is “trodden” between these two zones: from the focus caused by the conditioned stimulus to the focus caused by the unconditioned stimulus. As a result, the isolated presentation of only the conditioned stimulus now leads to the response caused by the previously unconditioned stimulus.

The main cellular elements of the central mechanism for the formation of a conditioned reflex are intercalary and associative neurons of the cerebral cortex.

I. P. Pavlov initially assumed that the conditioned reflex is formed at the level of the cortex - subcortical formations (a temporary connection is made between cortical neurons in the zone of representation of the indifferent conditioned stimulus and the subcortical nerve cells that make up the central representation of the unconditioned stimulus). In later works, I. P. Pavlov explained the formation of a conditioned reflex connection by the formation of a connection at the level of the cortical zones of the representation of conditioned and unconditioned stimuli. Data from modern neurophysiology indicate the possibility of different levels of closure, the formation of a conditioned reflex connection (cortex - cortex, cortex - subcortical formations, subcortical formations - subcortical formations) with a dominant role in this process of cortical structures. Obviously, the physiological mechanism for the formation of a conditioned reflex is a complex dynamic organization of cortical and subcortical structures.

Biological significance of conditioned reflexes is that they make it possible to adapt much better and more accurately to the conditions of existence and to survive in these conditions. As a result of the formation of conditioned reflexes, the body reacts not only directly to unconditioned stimuli, but also to the possibility of their action on it; reactions appear some time before unconditional irritation. In this way, the body is prepared in advance for the actions that it has to carry out in a given situation. Conditioned reflexes contribute to finding food, avoiding danger in advance, eliminating harmful influences, etc. The adaptive significance of conditioned reflexes is also manifested in the fact that the precedence of a conditioned stimulus to an unconditioned one strengthens the unconditioned reflex and accelerates its development.

After his death, Pavlov's orthodox followers tried to fit almost any form of mental activity into the theory of conditioned reflexes. So, for example, if a conditioned salivary reflex to a bell has been formed, then you can use the bell as a reinforcer after, for example, turning on a light bulb and thereby ensure that just turning on the light bulb will also cause salivation. Reflexes of this type, where a previously formed temporary connection is used as reinforcement, are called conditioned. second order reflexes. It is not difficult to imagine the formation of reflexes of the third, fourth, etc. orders according to the same principle. A person can form, for example, a reflex of order 12 or more. However, from all this kind of evidence it still does not come out that the creation of the theory of relativity or Mona Lisa is simply the result of conditioned reflex activity. Conditioned reflexes of the second and more complex order are more difficult to form and are less durable. Conditioned reflexes of the second and higher order include conditioned reflexes produced in response to a verbal signal (the word here represents a signal to which a conditioned reflex was previously formed when reinforced by an unconditioned stimulus).

Inhibition of conditioned reflexes. Unlike unconditioned reflexes, conditioned reflexes are easily inhibited.

Depending on the nature of the physiological mechanism underlying the inhibitory effect on the conditioned reflex activity of the body, distinguish between unconditional(external and beyond) and conditional(internal) braking conditioned reflexes.

External braking a conditioned reflex occurs under the influence of extraneous stimuli that cause a new reflex reaction. This inhibition is called external because it develops as a result of processes occurring in areas of the cortex that are not involved in the implementation of this conditioned reflex. External inhibition occurs when the corresponding signal is first presented. So, if before the onset of the conditioned food reflex a foreign sound suddenly appears or some foreign smell appears, or the lighting changes sharply, then the conditioned reflex decreases or even disappears completely. This is explained by the fact that any new stimulus causes an orienting reflex, which inhibits the conditioned reaction.

Extreme braking The conditioned reflex develops either when the strength of the stimulus is excessively high, or when the functional state of the central nervous system is low, at the level of which ordinary threshold stimuli acquire the character of excessive, strong ones. Extreme inhibition has a protective value.

The biological meaning of unconditional external inhibition of conditioned reflexes comes down to ensuring a reaction to the most important stimulus for the body at a given moment in time while simultaneously suppressing the reaction to a secondary stimulus, which in this case is a conditioned stimulus.

Conditioned inhibition a conditioned reflex requires special development. Since the development of the inhibitory effect is associated with the neurophysiological mechanism of formation of the conditioned reflex, such inhibition belongs to the category of internal inhibition, and the manifestation of this type of inhibition is associated with certain conditions (for example, repeated application of a conditioned stimulus without reinforcement), such inhibition is also conditional.

The biological meaning of internal inhibition of conditioned reflexes is that changed environmental conditions (cessation of reinforcement of a conditioned stimulus by an unconditioned one) require a corresponding adaptive change in conditioned reflex behavior. The conditioned reflex is suppressed, suppressed, because it ceases to be a signal foreshadowing the appearance of an unconditioned stimulus.

There are four types of internal inhibition: extinction, differentiation, conditioned inhibition, delay.

If a conditioned stimulus is presented without reinforcement by an unconditioned one, then some time after the isolated application of the conditioned stimulus, the reaction to it fades away. This inhibition of the conditioned reflex is called fading(fading). Extinction of a conditioned reflex- this is a temporary inhibition, suppression of a reflex reaction. It does not mean the destruction or disappearance of this reflex reaction. After some time, a new presentation of a conditioned stimulus without reinforcement by an unconditioned one initially again leads to the manifestation of a conditioned reflex reaction.

If a dog develops a food salivary conditioned reflex to metronome beats with a frequency of 60 times per minute, then the animal will first respond by secreting saliva to metronome beats of any frequency. If you give the animal two stimuli - metronome beats at a frequency of 60 and 100 times per minute and the first of them, as before, is reinforced with food, but the second is not, then gradually the secretion of saliva at a frequency of 100 beats will stop and will persist only at 60. This type of internal ( conditioned) inhibition is called differential inhibition(differentiation). Differential inhibition underlies many forms of learning associated with the development of fine skills.

If a conditioned stimulus to which a conditioned reflex is formed is used in combination with some other stimulus and their combination is not reinforced by an unconditioned stimulus, inhibition of the conditioned reflex caused by this stimulus occurs. This type of conditioned inhibition is called conditional brake.

Delayed braking occurs when the reinforcement of the conditioned signal by the unconditioned stimulus is carried out with a large delay (2-3 minutes) in relation to the moment of presentation of the conditioned stimulus.

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

Reflexes unconditioned and conditioned.

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

These include:

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

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

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

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

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

A reflex is the body's response to internal or external stimulation, carried out and controlled by the central nervous system. The first scientists who developed ideas about what was previously a mystery were our compatriots I.P. Pavlov and I.M. Sechenov.

What are unconditioned reflexes?

An unconditioned reflex is an innate, stereotypical reaction of the body to the influence of the internal or environmental environment, inherited by the offspring from the parents. It remains in 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 environmental changes that often accompanied many generations of his ancestors.

What reflexes are unconditioned?

An unconditioned reflex is the main form of activity of the nervous system, an automatic reaction to a stimulus. And since a person is influenced by various factors, the reflexes are different: food, defensive, orientation, sexual... Food include salivation, swallowing and sucking. Defensive actions include coughing, blinking, sneezing, and jerking limbs away from hot objects. Approximate reactions include turning the head and squinting the eyes. Sexual instincts include those associated with reproduction, as well as caring for offspring. The significance of the unconditioned reflex is that it ensures the preservation of the integrity of the body and maintains the constancy of the internal environment. Thanks to him, reproduction occurs. Even in newborn children, one can observe an elementary unconditioned reflex - this is sucking. By the way, it is the most important. The irritant in this case is touching the lips of any object (pacifier, mother's breast, toy or finger). Another important unconditioned reflex is blinking, which occurs when a foreign body approaches the eye or touches the cornea. This reaction belongs to the protective or defensive group. Also observed in children, for example, when exposed to strong light. However, the signs of unconditioned reflexes are most clearly manifested in various animals.

What are conditioned reflexes?

Conditioned reflexes are those acquired by the body during life. They are formed on the basis of inherited ones, subject to exposure to an external stimulus (time, knocking, light, and so on). A striking example is the experiments conducted 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 method for obtaining them. So, to develop such reactions, the presence of a regular stimulus - a signal - is necessary. It triggers the mechanism, and repeated repetition of the stimulus allows it 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 awakens under the influence of fundamentally new external signals. These stimuli from the surrounding world, to which the body was previously indifferent, begin to acquire exceptional, vital importance. Each living creature can develop many different conditioned reflexes during its life, which form the basis of its experience. However, this applies only to this particular individual; this life experience will not be inherited.

An independent category of conditioned reflexes

It is customary to classify into a separate category conditioned reflexes of a motor nature developed throughout life, that is, skills or automated actions. Their meaning is to master new skills, as well as develop 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, and consciousness are freed up when performing operations that have reached automaticity and become a reality of everyday life. The most successful way to master skills is to systematically perform the exercise, timely correction of noticed errors, and knowledge of the ultimate goal of any task. If the conditioned stimulus is not reinforced by the unconditioned stimulus for some time, it is inhibited. However, it does not disappear completely. If you repeat the action after some time, the reflex will be restored fairly quickly. Inhibition can also occur when a stimulus of even greater strength appears.

Compare unconditioned and conditioned reflexes

As mentioned above, these reactions differ in the nature of their occurrence and have different formation mechanisms. In order to understand what the difference is, just compare unconditioned and conditioned reflexes. Thus, the first ones are present in a living creature from birth; throughout life they do not change or disappear. In addition, unconditioned reflexes are the same in all organisms of a particular species. Their significance lies in preparing a living being for constant conditions. The reflex arc of this reaction passes through the brain stem or spinal cord. As an example, here are some (congenital): active secretion of saliva when a lemon enters the mouth; sucking movement of the newborn; coughing, sneezing, withdrawing hands from a hot object. Now let's look at the characteristics of conditioned reactions. They are acquired throughout life, can change or disappear, and, no less important, each organism has its own individual (its own). Their main function is to adapt a living creature 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.

Unconditioned reflex diagram

According to the research of academician I.P. Pavlova, the general scheme of unconditioned reflexes is as follows. Certain receptor nerve devices are affected by certain stimuli from the internal or external world of the body. As a result, the resulting irritation transforms the entire process into the so-called phenomenon of nervous excitation. It is transmitted along nerve fibers (as if 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 a given part of the body. It turns out that certain stimuli are naturally connected with this or that activity in the same way as cause and effect.

Features of unconditioned reflexes

The characteristics of unconditioned reflexes presented below systematize the material presented above; it will help to finally understand the phenomenon we are considering. So, what are the features of inherited reactions?

Unconditioned instinct and reflex of animals

The exceptional constancy of the nervous connection underlying unconditional instinct is explained by the fact that all animals are born with a nervous system. She is already able to respond appropriately to specific environmental stimuli. For example, a creature may flinch at a sharp sound; he will secrete digestive juice and saliva when food enters his mouth or stomach; it will blink when visually stimulated, 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.

An unconditioned reflex, in fact, is not a completely monotonous, template, transfer reaction of an animal to an external stimulus. It is characterized, although elementary, primitive, but still by variability, variability, depending on external conditions (strength, peculiarities of the situation, position of the stimulus). In addition, it is influenced by the internal states of the animal (decreased or increased activity, posture, etc.). So, also I.M. Sechenov, in his experiments with decapitated (spinal) frogs, showed that when the toes of the hind legs of this amphibian are exposed, 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 animal’s adaptation to new or sharply changing conditions.

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

Species specificity

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

Unconditional inhibition

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 capable of causing a corresponding reaction - a reflex. If all of them could be realized, then the life 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 unconditioned reflexes are inhibited in the body. This means that the most important reflex at a particular moment in time delays the secondary ones. Typically, external inhibition can occur at the moment of starting another activity. The new pathogen, 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 newcomer. There is a sharp change in activity, and the dog’s salivation stops at this moment. Unconditional inhibition of reflexes also includes some innate reactions. In them, certain pathogens cause the complete cessation of certain actions. For example, the anxious clucking of a hen makes the chicks freeze and hug the ground, and the onset of darkness forces the canary to stop singing.

In addition, there is also a protective It arises as a response to a very strong stimulus that requires the body to take actions that exceed its capabilities. The level of such influence is determined by the frequency of impulses of the nervous system. The more excited a neuron is, the higher the frequency of the stream of nerve impulses it generates. However, if this flow exceeds certain limits, then a process will arise that will begin to interfere with the passage of excitation through the neural circuit. The flow of impulses along the reflex arc of the spinal cord and brain is interrupted, resulting in inhibition that preserves the executive organs from complete exhaustion. What conclusion follows from this? Thanks to the inhibition of unconditioned reflexes, the body selects from all possible options the most adequate one, capable of protecting against excessive activity. This process also contributes to the exercise of so-called biological precautions.

Such habitual actions as breathing, swallowing, sneezing, blinking occur without conscious control, are innate mechanisms, help a person or animal to survive and ensure the preservation of the species - all these are unconditioned reflexes.

What is an unconditioned reflex?

I.P. Pavlov, a scientist-physiologist, devoted his life to the study of higher nervous activity. In order to understand what human unconditioned reflexes are, it is important to consider the meaning of the reflex as a whole. Any organism that has a nervous system carries out reflex activity. Reflex is a complex reaction of the body to internal and external stimuli, carried out in the form of a reflex response.

Unconditioned reflexes are innate stereotypical reactions laid down at the genetic level in response to changes in internal homeostasis or environmental conditions. For the emergence of unconditioned reflexes, special conditions are automatic reactions that can fail only in severe diseases. Examples of unconditioned reflexes:

• withdrawing a limb from contact with hot water;
• knee reflex;
• sucking, grasping in newborns;
• swallowing;
• salivation;
• sneezing;
• blinking.

What is the role of unconditioned reflexes in human life?

Human evolution over the centuries has been accompanied by changes in the genetic apparatus, the selection of traits that are necessary for survival in the surrounding nature. became highly organized matter. What is the significance of unconditioned reflexes - answers can be found in the works of physiologists Sechenov, I.P. Pavlova, P.V. Simonova. Scientists have identified several important functions:

• maintaining homeostasis (self-regulation of the internal environment) in optimal balance;
• adaptation and adaptation of the body (mechanisms of thermoregulation, respiration, digestion);
• preservation of species characteristics;
• reproduction.

Signs of unconditioned reflexes

The main feature of unconditioned reflexes is innateness. Nature made sure that all functions important for life in this world were reliably recorded on the DNA nucleotide chain. Other characteristic features:

• preliminary training and control of consciousness are not required;
• are specific;
• strictly specific - occur upon contact with a specific stimulus;
• constant reflex arcs in the lower parts of the central nervous system;
• most unconditioned reflexes persist throughout life;
• a set of unconditioned reflexes helps the body adapt to the environment in the early stages of development;
• are the basic basis for the emergence of conditioned reflexes.

Types of unconditioned reflexes

Unconditioned reflexes have different types of classification, I.P. Pavlov was the first to classify them into: simple, complex and most complex. In the distribution of unconditioned reflexes according to the factor of certain space-time regions occupied by each creature, P.V. Simonov divided the types of unconditioned reflexes into 3 classes:

1. Role unconditioned reflexes– manifest themselves in interaction with other intraspecific representatives. These are reflexes: sexual, territorial behavior, parental (maternal, paternal), phenomenon.
2. Unconditioned vital reflexes– all the basic needs of the body, the deprivation or dissatisfaction of which leads to death. Provide individual safety: drinking, food, sleep and wakefulness, orientation, defensive.
3. Unconditioned reflexes of self-development- are included when mastering something new, previously unfamiliar (knowledge, space):

• reflex of overcoming or resistance (freedom);
• game;
• imitative.

Types of inhibition of unconditioned reflexes

Excitation and inhibition are important innate functions of higher nervous activity, which ensure the coordinated activity of the body and without which this activity would be chaotic. Inhibitory unconditioned reflexes in the process of evolution turned into a complex response of the nervous system - inhibition. I.P. Pavlov identified 3 types of inhibition:

1. Unconditional inhibition (external)– reaction “What is it?” allows you to assess whether the situation is dangerous or not. In the future, with frequent manifestations of an external stimulus that does not pose a danger, inhibition does not occur.
2. Conditioned (internal) inhibition– the functions of conditioned inhibition ensure the extinction of reflexes that have lost their value, help distinguish useful signals with reinforcement from useless ones, and form a delayed reaction to a stimulus.
3. Transcendental (protective) inhibition- an unconditional safety mechanism provided by nature, which is triggered by excessive fatigue, excitement, severe injuries (fainting, coma).