What is called an unconditioned reflex. Congenital and acquired forms of behavior

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

Classification of unconditioned reflexes.

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

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

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

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

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

5.Sexual reflexes.

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

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

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

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

Physiological mechanisms of formation of conditioned reflexes

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

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

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

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

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

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

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

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

4. Repetition.

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

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

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

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

Classifications of conditioned reflexes

Due to their large number it is difficult.

According to the location of the receptor:

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

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

3. proprioceptive, arising from irritation of muscle receptors.

By the nature of the receptor:

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

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

By action sign:

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

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

By the nature of the response:

1. motor;

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

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

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

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

Abstract on the topic:

"Conditioned and unconditioned reflexes"

Donetsk 2010

Introduction.

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

2. Classification of unconditioned reflexes.

3. The mechanism of formation of conditioned reflexes.

4. Conditions for the formation of conditioned reflexes.

5. Classification of conditioned reflexes.

Conclusion.

List of used literature.

Introduction.

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

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

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

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

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

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

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

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

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

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

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

2. Classification of unconditioned reflexes.

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

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

1. food

2. defensive

3. genitals

4. approximate

5. parental

6. children's.

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

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

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

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

Parental reflexes are reflexes that underlie care for offspring.

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

3. The mechanism of formation of conditioned reflexes.

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

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

4. Conditions for the formation of conditioned reflexes.

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

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

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

3) vigorous state of the body;

4) absence of other types of active activity;

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

6) suprathreshold intensity of the conditioned stimulus.

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

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

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

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

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

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

5. Classification of conditioned reflexes.

Conditioned reflexes are divided according to several criteria.

1. By biological significance distinguish:

1) food;

2) sexual;

3) defensive;

4) motor;

5) indicative - reaction to a new stimulus.

The indicative reflex occurs in 2 phases:

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

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

Differences between the orienting reflex and other conditioned reflexes:

1) innate reaction of the body;

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

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

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

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

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

3) interoceptive – affect mood and performance.

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

1) somatic (motor);

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

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

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

The main laboratory conditioned reflexes are the following.

1. By difficulties distinguish:

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

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

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

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

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

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

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

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

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

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

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

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

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

Conclusion.

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

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

List of used literature.

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

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

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

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

To pull your hand away from a hot kettle, to close your eyes when there is a flash of light... We perform such actions automatically, without having time to think about what exactly we are doing and why. These are unconditioned human reflexes - innate reactions characteristic of all people without exception.

Discovery history, types, differences

Before examining unconditioned reflexes in detail, we will have to take a short excursion into biology and talk about reflex processes in general.

So what is a reflex? In psychology, this is the name given to the body’s response to changes in the external or internal environment, which is carried out using the central nervous system. Thanks to this ability, the body quickly adapts to changes in the surrounding world or in its internal state. For its implementation, a reflex arc is necessary, that is, the path along which the signal of irritation passes from the receptor to the corresponding organ.

Reflex reactions were first described by Rene Descartes in the 17th century. But the French scientist believed that this was not a psychological phenomenon. He considered reflexes as part of objective natural science knowledge, while psychology at that time was considered not a science, because it dealt only with subjective reality and was not subject to objective experiment.

The very concept of “reflex” was introduced in the second half of the 19th century by the Russian physiologist I.M. Sechenov. He proved that reflex activity constitutes a single principle of operation of the entire central nervous system. The scientist demonstrated that the initial cause of a mental phenomenon or human action is determined by the influence of the external environment or irritation of the nervous system within the body.

And if the sense organs do not experience irritation, and sensitivity is lost, mental life freezes. Let us remember the well-known expression: “get tired until you lose your senses.” And indeed, when we are very tired, we, as a rule, do not dream and become almost insensitive to external stimuli: noise, light, even pain.

Sechenov’s research was continued by I.P. Pavlov. He came to the conclusion that there are innate reflexes that do not require any special conditions, and acquired, arising during the body’s adaptation to the external environment.

Surely many will now remember Pavlov’s famous dog. And not in vain: while studying digestion in animals, the scientist noticed that in the experimental dogs, salivation began not when food was served, but already at the sight of the researcher’s assistant, who usually brought food.

If the release of saliva when food is served is a typical unconditioned reflex, and it is characteristic of all dogs, then saliva even at the sight of a helper is a typical conditioned reflex developed in individual animals. Hence the main difference between the two types: genetic or occurrence under the influence of the environment. In addition, unconditioned and conditioned reflexes differ in a number of indicators.

• Unconditioned are present in all individuals of the species, regardless of their living conditions; conditional, on the contrary, arise under the influence of the individual living conditions of the organism (this difference is clear from the name of each species).
• Unconditioned reactions are the foundation on which conditioned ones can be formed, but they need constant reinforcement.
• Reflex arcs of unconditioned reflexes are closed in the lower parts of the brain, as well as in the spinal cord. The conditioned arcs are formed in the cerebral cortex.
• Unconditioned reflex processes remain unchanged throughout a person’s life, although they can be somewhat transformed in the case of a serious illness. Conditional - arise and disappear. In other words, in one case the reflex arcs are permanent, in the other they are temporary.

From these differences it is easy to add up general characteristics unconditioned reflexes: they are hereditary, unchangeable, inherent in all representatives of the species and support the life of the organism in constant environmental conditions.

Where do they arise?

As already mentioned, both conditioned and unconditioned reflexes are possible thanks to the work of the central nervous system. Its most important components are the brain and spinal cord. As an example of an unconditioned reflex for which the spinal cord is responsible, we can cite the well-known knee reflex.

The doctor gently hits a certain place with a hammer, which causes involuntary extension of the lower leg. Normally, this reflex should be of average severity, but if it is too weak or too strong, this is most likely evidence of pathology.

Unconditioned reflexes of the brain are numerous. In the lower parts of this organ there are various reflex centers. So, if you move up from the spinal cord, the first is the medulla oblongata. Sneezing, coughing, swallowing, salivation - these reflex processes are possible precisely thanks to the work of the medulla oblongata.

Under the control of the midbrain - reactions that occur in response to visual or auditory impulses. This includes constriction or dilation of the pupil depending on the amount of light falling on it, a reflexive turn towards the source of sound or light. The effect of such reflexes extends only to unfamiliar stimuli.

That is, for example, when there are numerous sharp sounds, a person will each time turn to a new place where the noise originates, rather than continue to listen, trying to understand where the first sound came from. The so-called unconditioned reflex of straightening the posture is closed through the intermediate part of the brain. These are the muscle contractions with which our body responds to changes in posture; they allow the body to be held in a new position.

Classification

Classification of unconditioned reflexes is carried out according to different criteria. For example, there is a division that is understandable even to a non-specialist into simple, complex and extremely complex.

The example given at the beginning of the text about pulling your hand away from the kettle is a simple unconditioned reflex. Complex problems include, for example, sweating. And if we are dealing with a whole chain simple actions, then we are already talking about a group of the most complex: say, self-preservation reflexes, caring for offspring. This set of behavior programs is usually called instinct.

The classification is quite simple based on the body’s relationship to the stimulus. If you rely on it, unconditioned reflex reactions are divided into positive (search for food by smell) and negative (desire to escape from the source of noise).

According to their biological significance, the following types of unconditioned reflexes are distinguished:

• Nutritional (swallowing, sucking, salivation).
• Sexual (sexual arousal).
• Defensive or protective (the same withdrawal of hands or the desire to cover the head with hands if a person thinks that a blow is about to follow).
• Indicative (the desire to identify unfamiliar stimuli: turning your head towards a sharp sound or touch). They were already discussed when we talked about the reflex centers of the midbrain.
• Locomotor, that is, serving for movement (support the body in a certain position in space).

Very often in scientific literature there is a classification proposed by the Russian scientist P. V. Simonov. He divided all unconditioned reflexes into three groups: vital, role and self-development reflexes.

Vital (from the Latin vitalis - “vital”) are directly related to the preservation of the very life of an individual. This is a nutritional, defensive, effort-saving reflex (if the result of actions is the same, something that takes less effort is chosen), regulation of sleep and wakefulness.

If the corresponding need is not satisfied, the physical existence of the organism ceases; another representative of the species is not needed to implement the reflex - these are the signs that unite all the reactions of this group.

Role-playing can be carried out, on the contrary, only through contact with another individual. These primarily include parental and sexual reflexes. The last group includes such reflexes as play, exploration, and the reflex of imitation of another individual.

Of course, there are other classification options, as well as other views on the methods of division given here. And this is not surprising: there is rarely unanimity among scientists.

Features and meaning

As we have already said, the reflex arcs of unconditioned reflexes are constant, but they themselves can be active at different periods of a person’s life. For example, sexual reflexes appear when the body reaches a certain age. Other reflex processes, on the contrary, fade away after a certain period of time. Suffice it to recall the unconscious grasping of a baby by an adult’s finger when pressing on his palm, which disappears with age.

The importance of unconditioned reflexes is enormous. They help to survive not only an individual organism, but the entire species. They are most significant in the early stages of a person’s life, when knowledge about the world has not yet been accumulated and the child’s activities are guided by reflex processes.

Unconditioned reflexes begin to work from the very moment of birth. Thanks to them, the body does not die during a sharp transition to new conditions of existence: adaptation to a new type of breathing and nutrition occurs instantly, and the mechanism of thermoregulation is gradually established.

Moreover, according to recent research, certain unconditioned reflexes are carried out even in the womb (for example, sucking). With age, more and more conditioned reflexes are added to the unconditioned ones, which allow a person to better adapt to a changing environment. Author: Evgenia Bessonova

1. What reflexes are called conditioned? Give examples of a conditioned reflex.

Conditioned reflexes are acquired by the body in the process of its development, i.e. they are individual. Conditioned reflexes do not have ready-made reflex arcs; they are formed under certain conditions. These reflexes are not constant; they can develop and disappear. The conditioned reflex is formed on the basis of the unconditioned reflex and is carried out due to the activity of the cerebral cortex. For the formation of conditioned reflexes, it is necessary to combine two stimuli in time: an indifferent (conditioned) one for a given type of activity (light, sound, for example, for digestion) and an unconditioned one, causing a certain unconditioned reflex (food, etc.). The conditional signal must precede the unconditional signal. Reinforcement of the conditioned signal by the unconditioned must be repeated in the absence of distracting extraneous stimuli. When a conditioned stimulus (for example, light) acts, a focus of excitation appears in the cortex. The subsequent action of an unconditioned stimulus (for example, food) is accompanied by the appearance of a second focus of excitation in the cortex. A temporary connection arises between them (a Pavlovian closure occurs). After several combinations of conditioned and unconditioned stimuli, the connection becomes stronger. Now only one conditioned stimulus is enough to trigger a reflex. An example of a conditioned reflex: salivation at the sight and smell of food.

Conditioned reflexes are not only developed, but also disappear or weaken when the conditions of existence change as a result of inhibition. I.P. Pavlov distinguished two types of inhibition of conditioned reflexes: unconditioned (external) and conditioned (internal). Unconditioned (external) inhibition occurs as a result of the action of a new stimulus of sufficient strength. In this case, a new focus of excitation appears in the cerebral cortex, which causes inhibition of the existing focus of excitation. In a person, for example, with an acute toothache, a severely wounded finger stops hurting. Conditioned (internal) inhibition develops according to the laws of the conditioned reflex, i.e. if the action of the conditioned stimulus is not reinforced by the action of the unconditioned stimulus. Thanks to inhibition in the cortex, unnecessary temporary connections disappear.

2. What reflexes are called unconditioned? Give examples of an unconditioned reflex.Material from the site

Unconditioned reflexes are innate and inherited. Unconditioned reflexes appear at the first application of the stimulus to the corresponding receptors. These reflexes have permanent inherited ready reflex arcs. They are inherent in all representatives of this species and are carried out in response to adequate stimulation. Unconditioned reflexes are carried out at the level of the spinal cord and brain stem, subcortical nuclei. Examples: salivation, swallowing, breathing, etc.

Conditioned reflex - a complex adaptive reaction of the body that occurs due to the formation of a temporary neural connection (association) between a signal (conditioned) and reinforcing it with an unconditioned stimulus.

Conditioned reflexes are formed on the basis of innate unconditioned reflexes. Conditioned reflexes are individual, acquired reflex reactions that are produced on the basis of unconditioned reflexes. Their signs:

1. Acquired throughout the life of the organism.
2. They are not the same among representatives of the same species.
3. They do not have ready-made reflex arcs.
4. They are formed under certain conditions.
5. In their implementation, the main role belongs to the cerebral cortex.
6. Changeable, easily arise and disappear easily depending on the conditions in which the body is located.

Conditions for the formation of conditioned reflexes:

1. The simultaneous action of two stimuli: indifferent for a given type of activity, which later becomes a conditioned signal, and an unconditioned stimulus, which causes a certain unconditioned reflex.
2. The action of the conditioned stimulus always precedes the action of the unconditioned (by 1-5 s.).
3. Reinforcement of the conditioned stimulus with the unconditioned must be repeated.
4. The unconditioned stimulus must be biologically strong, and the conditioned stimulus must have moderate optimal strength.
5. Conditioned reflexes are formed faster and easier in the absence of extraneous stimuli.

Conditioned reflexes can be produced not only on the basis of unconditioned ones, but also on the basis of previously acquired conditioned reflexes that have become quite strong. These are conditioned reflexes of the highest order. Conditioned reflexes are:

• natural - reflex reactions that are produced to changes environment, and always accompany the appearance of the unconditional. For example, the smell and appearance of food are natural signals of the food itself;
• artificial - conditioned reflexes produced in response to irritation, which do not have an unconditional effect reflex reaction natural relationship. For example, salivation for a call or for a while.

The conditioned reflex method is a method for studying GNI. I. P. Pavlov drew attention to the fact that the activity of the higher parts of the brain is not only associated with the direct influence of stimuli that have biological significance for the body, but also depends on the conditions that accompany these stimuli. For example, a dog begins to salivate not only when food enters its mouth, but also at the sight and smell of food, as soon as it sees the person who always brings it food. I.P. Pavlov explained this phenomenon by developing the method of conditioned reflexes. Using the method of conditioned reflexes, he conducted experiments on dogs with a fistula (stomy) of the excretory duct of the parotid salivary gland. The animal was offered two stimuli: food, a stimulus that has biological significance and causes salivation; the second is indifferent to the nutrition process (light, sound). These stimuli were combined in time so that the effect of light (sound) preceded the intake of food by several seconds. After a number of repetitions, saliva began to be released when the light bulb flashed and there was no food. Light (an indifferent stimulus) was called conditioned, since it is the condition under which food intake took place. A stimulus that has biological significance (food) is called unconditioned, and the physiological reaction of salivation, which occurs as a result of the action of a conditioned stimulus, is called a conditioned reflex.

To find out the mechanism of formation of conditioned reflexes, partial isolation of certain parts of the cerebral cortex and recording of the electrical activity of various brain structures during the action of unconditioned and conditioned stimuli are used.

I.P. Pavlov believed that with simultaneous action on two different analyzers in different sensitive areas of the cerebral hemispheres, excitation occurs, and over time, a connection is formed between them. For example, when a light bulb lights up and this stimulus is reinforced with food, excitation occurs in the cortical part of the visual analyzer, located in the occipital region of the cortex and excitation of the food center of the cerebral cortex - that is, in both cortical centers (visual and food), between which a nerve connection is formed. , which, with repeated combinations of these stimuli over time, becomes durable.

With conditioned reflexes, as with unconditioned reflexes, reverse afferentia occurs, that is, a signal that a conditioned reflex reaction has taken place. It allows the central nervous system to evaluate behavioral acts. Without such an assessment, subtle adaptation of behavior to constantly changing environmental conditions is impossible.

Studies of animals in which areas of the cortex were removed showed that conditioned reflexes could be developed in these animals. So, conditioned reflexes are formed due to the interaction of the cerebral cortex and subcortical centers. The structure of the reflex arc of a conditioned reflex is complex. Thus, in the formation of complex behavioral reactions, the cortex has a leading role, and in the formation of autonomic conditioned reflexes, the cortex and subcortical structures play the same role. It has been proven that the destruction of the reticular formation delays the formation of conditioned reflexes, and its irritation electric shock accelerates their formation. What are the signals of the conditioned reflex? Any changes in the environment or internal state of the body can become a conditioned stimulus if they:

1. they themselves do not cause an unconditional reflex; they are indifferent.
2. their strength is sufficient to cause an unconditioned orienting reflex.

For example, sounds, light, colors, smells, tastes, touch, pressure, heat, cold, body position in space - all these and others "indifferent" stimuli, when combined with an unconditioned stimulus and provided they are of sufficient strength, become signals that evoke one or another unconditioned reflex.

Biological significance of conditioned reflexes

The biological significance of conditioned reflexes lies in the fact that they are adaptive reactions of the body, which are formed by the living conditions of a person and make it possible to adapt in advance to new conditions. Conditioned reflexes have a warning signal value, since the body begins to react purposefully before a vital stimulus begins to act. Therefore, conditioned reflexes provide a living creature with the opportunity to assess danger or a red stimulus in advance, as well as the ability to carry out purposeful actions and consciously avoid mistakes.

10 questions in biology on the topic: unconditioned and conditioned reflexes.

1. What are unconditioned reflexes? "Unconditioned reflexes" - These are specific, innate, relatively constant reactions of the body to the influence of the external and internal environment, carried out with the help of the nervous system.
2. What are the main types of unconditioned reflexes? The main types of unconditioned reflexes include respiratory, food, grasping, protective, orientation and sexual.
3. What are instincts? Complex system innate (insanely reflexive) behavioral programs associated with the preservation of the species are called instincts (from the Latin instinctus - urge, motive).
4. What are conditioned reflexes? Conditioned reflexes, in contrast to unconditioned ones, are individual, arise during a person’s life, and are characteristic only of it; are temporary and may decline with changing environmental conditions.
5. What conditions are needed for the formation of conditioned reflexes? Conditioned reflexes are formed on the basis of unconditioned ones.
6. The mechanism of formation of conditioned reflexes? I.P. Pavlov found that the formation of conditioned reflexes is based on the establishment of temporary connections in the cerebral cortex between the nerve centers of the unconditioned reflex and the conditioned stimulus.
7. What are the types of conditioned reflexes? natural - reflex reactions that are produced to changes in the environment, and always accompany the emergence of the unconditional. For example, the smell and appearance of food are natural signals of the food itself; artificial - conditioned reflexes produced in response to stimulation, which have no natural relation to the unconditional reflex reaction. For example, salivation for a call or for a while.
8. Examples of unconditioned reflexes: blinking, breathing, reaction to sounds (indicative reflex), knee reflex.
9. Examples of conditioned reflexes for recognizing food by smell, the processes of standing, running, walking, speaking, writing, and labor actions.
10. Defensive reflexes are
    1. Unconditional.
    2. Conditional (conditional play a lesser role in defense)