Unconditioned reflexes examples. Congenital and acquired forms of behavior

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 cortex cerebral hemispheres. For education 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- congenital, inherited. Unconditioned reflexes appear at the first application of the stimulus to the corresponding receptors. These reflexes have permanent inherited ready-made 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.

Differences between conditioned reflexes and unconditioned ones. Unconditioned reflexes are innate reactions of the body; they were formed and consolidated in the process of evolution and are inherited. Conditioned reflexes arise, become consolidated, and fade away throughout life and are individual. Unconditioned reflexes are specific, i.e. they are found in all individuals of a given species. Conditioned reflexes may be developed in some individuals of a given species, but absent in others; they are individual. Unconditioned reflexes do not require special conditions for their occurrence; they necessarily arise if adequate stimuli act on certain receptors. Conditioned reflexes require special conditions for their formation; they can be formed in response to any stimuli (of optimal strength and duration) from any receptive field. Unconditioned reflexes are relatively constant, persistent, unchanging and persist throughout life. Conditioned reflexes are changeable and more mobile.

Unconditioned reflexes can occur at the level of the spinal cord and brain stem. Conditioned reflexes can be formed in response to any signals perceived by the body and are primarily a function of the cerebral cortex, realized with the participation of subcortical structures.

Unconditioned reflexes can ensure the existence of an organism only at the very early stage of life. The body's adaptation to constantly changing environmental conditions is ensured by conditioned reflexes developed throughout life. Conditioned reflexes are changeable. In the process of life, some conditioned reflexes, losing their meaning, fade away, while others are developed.

Biological significance of conditioned reflexes. The body is born with a certain fund of unconditioned reflexes. They provide him with the maintenance of vital functions in relatively constant conditions of existence. These include unconditioned reflexes: food (chewing, sucking, swallowing, secretion of saliva, gastric juice, etc.), defensive (pulling a hand away from a hot object, coughing, sneezing, blinking when a stream of air enters the eye, etc.), sexual reflexes (reflexes associated with sexual intercourse, feeding and caring for offspring), thermoregulatory, respiratory, cardiac, vascular reflexes that maintain the constancy of the internal environment of the body (homeostasis), etc.

Conditioned reflexes provide a more perfect adaptation of the body to changing living conditions. They help to find food by smell, timely escape from danger, and orientation in time and space. Conditioned reflex separation of saliva, gastric, pancreatic juices in appearance, smell, meal time creates Better conditions to digest food before it enters the body. Enhancing gas exchange and increasing pulmonary ventilation before starting work, only when seeing the environment in which the work is being done, contributes to greater endurance and better performance of the body during muscular activity.

When a conditioned signal is applied, the cerebral cortex provides the body with preliminary preparation for responding to those environmental stimuli that will subsequently have an impact. Therefore, the activity of the cerebral cortex is signaling.

Conditions for the formation of a conditioned reflex. Conditioned reflexes are developed on the basis of unconditioned ones. The conditioned reflex was so named by I.P. Pavlov because certain conditions are needed for its formation. First of all, you need a conditioned stimulus, or signal. A conditioned stimulus can be any stimulus from the external environment or a specific change internal state body. In the laboratory of I.P. Pavlov, the flashing of an electric light bulb, the bell, the gurgling of water, skin irritation, taste, olfactory stimuli, the clinking of dishes, the sight of a burning candle, etc. were used as conditioned stimuli. Conditioned reflexes are temporarily developed in a person by observing a work regime, eating at the same time, consistent with bedtime.

A conditioned reflex can be developed by combining an indifferent stimulus with a previously developed conditioned reflex. In this way, conditioned reflexes of the second order are formed, then the indifferent stimulus must be reinforced with a conditioned stimulus of the first order. It was possible to form conditioned reflexes of the third and fourth orders in the experiment. These reflexes are usually unstable. Children managed to develop sixth-order reflexes.

The possibility of developing conditioned reflexes is hampered or completely eliminated by strong extraneous stimuli, illness, etc.

In order to develop a conditioned reflex, the conditioned stimulus must be reinforced with an unconditioned stimulus, that is, one that evokes an unconditioned reflex. The clinking of knives in the dining room will cause a person to salivate only if this clinking has been reinforced with food one or more times. The ringing of knives and forks in our case is a conditioned stimulus, and the unconditioned stimulus that causes the salivary unconditioned reflex is food. The sight of a burning candle can become a signal for a child to withdraw his hand only if at least once the sight of a candle coincides with pain from a burn. When a conditioned reflex is formed, the conditioned stimulus must precede the action of the unconditioned stimulus (usually by 1-5 s).

The mechanism of formation of a conditioned reflex. According to the ideas of I.P. Pavlov, the formation of a conditioned reflex is associated with the establishment of a temporary connection between two groups of cortical cells: between those who perceive conditioned and those who perceive unconditional stimulation. This connection becomes stronger the more often both areas of the cortex are simultaneously excited. After several combinations, the connection turns out to be so strong that under the influence of only one conditioned stimulus, excitation also occurs in the second focus (Fig. 15).

Initially, an indifferent stimulus, if it is new and unexpected, causes a general generalized reaction of the body - an orienting reflex, which I. P. Pavlov called the exploratory or “what is it?” reflex. Any stimulus, if used for the first time, causes a motor reaction (general shudder, turning the eyes and ears towards the stimulus), increased breathing, heartbeat, generalized changes in the electrical activity of the brain - the alpha rhythm is replaced by rapid oscillations (beta rhythm). These reactions reflect generalized generalized arousal. When a stimulus is repeated, if it does not become a signal for a specific activity, the orienting reflex fades away. For example, if a dog hears a bell for the first time, it will give a general approximate reaction to it, but will not produce saliva. Let's back it up now ringing bell food. In this case, two foci of excitation will appear in the cerebral cortex - one in the auditory zone, and the other in the food center (these are areas of the cortex that are excited under the influence of the smell and taste of food). After several reinforcements of the bell with food, a temporary connection will arise (close) in the cerebral cortex between the two foci of excitation.

In the course of further research, facts were obtained indicating that the closure of the temporary connection occurs not only along horizontal fibers (bark - bark). With cuts gray matter separated different areas of the cortex in dogs, but this did not prevent the formation of temporary connections between the cells of these areas. This gave reason to believe that the cortex-subcortex-cortex pathway also plays an important role in establishing temporary connections. In this case, centripetal impulses from the conditioned stimulus through the thalamus and nonspecific system (hippocampus, reticular formation) enter the corresponding zone of the cortex. Here they are processed and along descending pathways reach the subcortical formations, from where the impulses come again to the cortex, but already in the zone of representation of the unconditioned reflex.

What happens in the neurons involved in the formation of a temporary connection? There are different points of view on this matter. One of them assigns the main role to morphological changes in the endings of nerve processes.

Another point of view about the mechanism of the conditioned reflex is based on the principle of dominance by A. A. Ukhtomsky. In the nervous system at each moment of time there are dominant foci of excitation - dominant foci. The dominant focus has the property of attracting to itself the excitation entering other nerve centers, and thereby intensifying. For example, during hunger, a persistent focus with increased excitability appears in the corresponding parts of the central nervous system - a food dominant. If you let a hungry puppy lap milk and at the same time begin to irritate the paw with an electric current, then the puppy does not withdraw its paw, but begins to lap with even greater intensity. In a well-fed puppy, irritation of the paw with an electric current causes a reaction of its withdrawal.

It is believed that during the formation of a conditioned reflex, the focus of persistent excitation that arose in the center of the unconditioned reflex “attracts” to itself the excitation that arose in the center of the conditioned stimulus. As these two excitations combine, a temporary connection is formed.

Many researchers believe that the leading role in fixing the temporary connection belongs to changes in protein synthesis; Specific protein substances associated with imprinting a temporary connection have been described. The formation of a temporary connection is associated with the mechanisms of storing traces of excitation. However, memory mechanisms cannot be reduced to “belt connection” mechanisms.

There is evidence of the possibility of storing traces at the level of single neurons. Cases of imprinting from a single action of an external stimulus are well known. This gives grounds to believe that the closure of a temporary connection is one of the mechanisms of memory.

Inhibition of conditioned reflexes. Conditioned reflexes are plastic. They can persist for a long time, or they can be inhibited. Two types of inhibition of conditioned reflexes have been described - internal and external.

Unconditional, or external, inhibition. This type of inhibition occurs in cases where in the cerebral cortex, during the implementation of a conditioned reflex, a new, sufficiently strong focus of excitation appears, not associated with this conditioned reflex. If a dog has developed a conditioned salivary reflex to the sound of a bell, then turning on a bright light at the sound of a bell in this dog inhibits the previously developed salivation reflex. This inhibition is based on the phenomenon of negative induction: a new strong focus of excitation in the cortex from extraneous stimulation causes a decrease in excitability in the areas of the cerebral cortex associated with the implementation of the conditioned reflex, and, as a consequence of this phenomenon, inhibition of the conditioned reflex occurs. Sometimes this inhibition of conditioned reflexes is called inductive inhibition.

Inductive inhibition does not require development (that is why it is classified as unconditioned inhibition) and develops immediately as soon as an external stimulus, foreign to the given conditioned reflex, acts.

External braking also includes transcendental braking. It manifests itself when the strength or time of action of the conditioned stimulus increases excessively. In this case, the conditioned reflex weakens or completely disappears. This inhibition has a protective value, as it protects nerve cells from stimuli of too great strength or duration that could disrupt their activity.

Conditioned, or internal, inhibition. Internal inhibition, in contrast to external inhibition, develops within the arc of the conditioned reflex, i.e. in those nerve structures ah, which participate in the implementation of this reflex.

If external inhibition occurs immediately as soon as the inhibitory agent has acted, then internal inhibition must be developed; it occurs under certain conditions, and this sometimes takes a long time.

One type of internal inhibition is extinction. It develops if the conditioned reflex is not reinforced by an unconditioned stimulus many times.

Some time after extinction, the conditioned reflex can be restored. This will happen if we again reinforce the action of the conditioned stimulus with the unconditioned one.

Fragile conditioned reflexes are restored with difficulty. Extinction can explain the temporary loss of labor skills and the ability to play musical instruments.

In children, decline occurs much more slowly than in adults. This is why it is difficult to wean children from bad habits. Extinction is the basis of forgetting.

The extinction of conditioned reflexes is important biological significance. Thanks to it, the body stops responding to signals that have lost their meaning. How many unnecessary, superfluous movements would a person make during writing, labor operations, and sports exercises without extinctive inhibition!

The delay of conditioned reflexes also refers to internal inhibition. It develops if the reinforcement of a conditioned stimulus by an unconditioned stimulus is delayed. Usually, when developing a conditioned reflex, a conditioned stimulus-signal (for example, a bell) is turned on, and after 1-5 s food is given (unconditioned reinforcement). When the reflex is developed, immediately after the bell is turned on, without giving food, saliva begins to flow. Now let’s do this: turn on the bell, and gradually delay the food reinforcement until 2-3 minutes after the bell starts sounding. After several (sometimes very multiple) combinations of a sounding bell with delayed reinforcement with food, a delay develops: the bell turns on, and saliva will no longer flow immediately, but 2-3 minutes after the bell is turned on. Due to the non-reinforcement of the conditioned stimulus (bell) for 2-3 minutes by the unconditioned stimulus (food), the conditioned stimulus acquires an inhibitory value during the period of non-reinforcement.

The delay creates conditions for better orientation of the animal in the surrounding world. The wolf does not immediately rush at the hare when it sees it at a considerable distance. He waits for the hare to approach. From the moment the wolf saw the hare until the time the hare approached the wolf, a process of internal inhibition took place in the wolf’s cerebral cortex: motor and food conditioned reflexes were inhibited. If this did not happen, the wolf would often be left without prey, breaking into pursuit as soon as he sees the hare. The resulting delay provides the wolf with prey.

Delay in children is developed with great difficulty under the influence of upbringing and training. Remember how a first-grader impatiently reaches out his hand, waving it, getting up from his desk so that the teacher notices him. And only by high school age (and even then not always) do we notice endurance, the ability to restrain our desires, and willpower.

Similar sound, olfactory and other stimuli can signal completely different events. Only an accurate analysis of these similar stimuli ensures biologically appropriate reactions of the animal. Analysis of stimuli consists of distinguishing, separating different signals, differentiating similar interactions on the body. In the laboratory of I.P. Pavlov, for example, it was possible to develop the following differentiation: 100 metronome beats per minute were reinforced with food, and 96 beats were not reinforced. After several repetitions, the dog distinguished 100 metronome beats from 96: at 100 beats she salivated, at 96 beats the saliva did not separate. Discrimination, or differentiation, of similar conditioned stimuli is developed by reinforcing some and non-reinforcing other stimuli. The inhibition that develops suppresses the reflex reaction to non-reinforced stimuli. Differentiation is one of the types of conditioned (internal) inhibition.

Thanks to differential inhibition, it is possible to identify signal-significant signs of a stimulus from many sounds, objects, faces, etc. around us. Differentiation is developed in children from the first months of life.

Dynamic stereotype. The external world acts on the body not with single stimuli, but usually with a system of simultaneous and sequential stimuli. If this system is often repeated in this order, then this leads to the formation of a dynamic stereotype.

A dynamic stereotype is a sequential chain of conditioned reflex acts, carried out in a strictly defined, time-fixed order and resulting from a complex systemic reaction of the body to a complex of conditioned stimuli. Thanks to the formation of chain conditioned reflexes, each previous activity of the body becomes a conditioned stimulus - a signal for the next one. Thus, by previous activity the body is prepared for the subsequent one. A manifestation of a dynamic stereotype is a conditioned reflex for time, which contributes to the optimal functioning of the body with the correct daily routine. For example, eating at certain hours ensures good appetite and normal digestion; Consistency in keeping a bedtime helps children and adolescents fall asleep quickly and thus sleep longer; Carrying out educational work and work activities always at the same hours leads to faster processing of the body and better absorption knowledge, skills, abilities.

A stereotype is difficult to develop, but if it is developed, then maintaining it does not require significant strain on cortical activity, and many actions become automatic. ;d A dynamic stereotype is the basis for the formation of habits in a person, the formation of a certain sequence in labor operations, and the acquisition of skills.

Walking, running, jumping, skiing, playing the piano, using a spoon, fork, knife when eating, writing - all these are skills that are based on the formation of dynamic stereotypes in the cerebral cortex.

The formation of a dynamic stereotype underlies the daily routine of every person. Stereotypes persist long years and form the basis of human behavior. Stereotypes that arise in early childhood are very difficult to change. Let us remember how difficult it is to “retrain” a child if he has learned to hold a pen incorrectly when writing, sit incorrectly at the table, etc. The difficulty of remaking stereotypes forces Special attention on the correct methods of raising and teaching children from the first years of life.

A dynamic stereotype is one of the manifestations of the systemic organization of higher cortical functions aimed at ensuring stable reactions of the body.

UNCONDITIONED REFLEX (specific, innate reflex) - a constant and innate reaction of the body to certain influences 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 I.P. Pavlov while studying 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 occurring reflex, I.P. Pavlov discovered a 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 corresponding external or internal stimulation, manifesting itself on the basis of innate nerve connections. Since the constancy of the corresponding unconditioned reflex is the result phylogenetic development given species of animal, then this reflex received the additional name “species reflex”.

The biological and physiological role of the unconditioned reflex is 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 I. P. Pavlov. The totality of the unconditioned reflex constitutes lower nervous activity, while the totality of acquired, or conditioned, reflexes constitutes higher nervous activity (see).

From this definition it follows that the unconditioned reflex, in its physiological meaning, 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 total direct the internal life of the organism. This last property of the unconditioned reflex was especially emphasized by I. P. Pavlov. great importance. Thanks to innate nerve connections that ensure the interaction of organs and processes within the body, animals and humans acquire an accurate and stable flow of basic vital functions. important functions. The principle on the basis of which these interactions and integration of activities within the body are organized is self-regulation of physiological functions (see).

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

1. Food, the causative agent of which is the action of nutrients 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, excitation of branched innate nervous structures occurs, which generally constitute 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. For example, applying painful stimulation to a limb causes the limb to be withdrawn, which protects it from further destructive effects.

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

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

4. Indicative and exploratory, which manifests itself fast movement heads towards the one who acted in this moment external stimulus. The biological meaning of this reflex consists in a detailed examination of the stimulus that acted and, in general, the external environment in which this stimulus arose. Thanks to the presence of innate pathways of this reflex in the central nervous system, the animal is able to respond expediently to sudden changes in the external world (see Orienting-exploratory reaction).

5. Reflexes with internal organs, reflexes when muscles and tendons are irritated (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, lead to the formation conditioned reactions very quickly, often after just one combination of any external stimulus with painful reinforcement. The ability of other unconditioned reflexes, for example, blinking or knee reflexes, to form temporary connections with indifferent external stimulus less pronounced.

It should also be taken into account that the speed 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 irritated taste buds tongue with certain foods, the reaction of the salivary glands in terms of the quality of secretion is in strict accordance with the physical and chemical properties food taken. If the food is dry, then watery saliva is released, 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 quality of food: saliva will contain a large number of mucous glucoprotein - mucin, which prevents injury to the food tract.

Fine receptor assessment is associated with a lack of a particular 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 developing bones, eventually its amount becomes below a constant level. This factor is a selective irritant of some specific cells of the hypothalamus, which in turn keeps the receptors of the tongue in a state of increased excitability. This is how children develop a desire to eat plaster, whitewash and other minerals containing calcium.

Such an appropriate correspondence of the unconditioned reflex to the quality and strength of the stimulus that acts depends on the extremely differentiated effect of nutrients and their combinations on the receptors of the tongue. By receiving these combinations of afferent excitations from the periphery, central office The unconditioned reflex sends efferent excitations to the peripheral apparatus (glands, muscles), leading to the formation of a certain composition of saliva or the occurrence of movements. In fact, the composition of saliva can be easily changed through a relative change in the production of its main ingredients: water, proteins, salts. It follows from this that the central salivary apparatus can vary the quantity and quality of excited elements depending on the quality of excitation coming from the periphery. The correspondence of an unconditioned response to the specificity of the applied stimulation can go very far. I.P. Pavlov developed the idea of the so-called digestive warehouse of certain unconditioned reactions. For example, if you feed an animal a certain type of food for a long time, the digestive juices of its glands (stomach, pancreas, 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 indicate that the stability, or immutability, of the unconditioned reflex is only relative. There is reason to think that already in the first days after birth, the specific “mood” of the tongue 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 in the mother’s milk that a newborn baby is fed on is increased, then the baby’s sucking movements are immediately inhibited, and in some cases the baby actively throws out the formula that has already been taken. This example convinces us that the innate properties of food receptors, as well as the properties of intranervous relationships, accurately reflect the needs of the newborn.

Methodology for using 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 techniques the use of the unconditioned reflex becomes especially important. In experiments on conditioned reflexes, the use of an unconditioned food reflex is based on feeding the animal with certain nutrients from an automatically fed feeder. With this method of using an unconditioned stimulus, the direct effect 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 certainly produces some kind of noise or knocking 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 technique 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 in oral cavity without preliminary sensations (sight, smell of food, etc.). Therefore, the method of directly introducing food into the mouth has some abnormal conditions and the animal’s reaction to the unusual nature of such a procedure.

In addition to this use of an unconditioned stimulus, there are a number of techniques 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) receives food by pressing the corresponding lever or button - the so-called instrumental reflexes.

The methodological features of reinforcement with an unconditioned stimulus have an undoubted influence on the results obtained. experimental results, and, therefore, the assessment of results should be made taking into account the type of unconditioned reflex. This especially applies to comparative assessment food and defensive unconditioned reflex.

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

Composition and localization of unconditioned reflexes

The development of experimental technology has made it possible to study the physiological composition and localization of the unconditioned food reflex in the central nervous system. For this purpose, the very effect of an 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 most quick view excitation that is part of unconditioned stimulation. Tactile receptors produce the fastest and highest-amplitude type of nerve impulses, which first spread along the lingual nerve to the medulla oblongata and only after a few fractions of a second (0.3 seconds) they arrive there nerve impulses from temperature and chemical irritation of tongue receptors. This feature of the unconditioned stimulus, manifested in the sequential excitation of various receptors of the tongue, has a huge physiological significance: conditions are created in the central nervous system for signaling with each previous stream of impulses about subsequent irritations. Thanks to such relationships and features of tactile excitation, depending on the mechanical qualities of a given food, in response only to these excitations, salivation can occur earlier than the effects of food. chemical qualities food.

Special experiments carried out on dogs and studies of the behavior of newborn children showed that such relationships between individual parameters unconditioned stimulus are used in the adaptive behavior of the newborn.

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

In the lives of adults, information about the tactile parameters of food is faster than information about chemical parameters. Thanks to this pattern, the sensation of “porridge”, “sugar”, etc. is born before it reaches the brain chemical signal. According to the teachings of I.P. Pavlov on the cortical representation of the unconditioned reflex, each unconditioned irritation, along with the inclusion of the subcortical apparatuses, has its own representation in the cerebral cortex. Based on the above data, as well as oscillographic and electroencephalographic analysis of the spread of unconditioned excitation, it was established that it does not have a single point or focus in the cerebral cortex. Each of the fragments of unconditional excitation (tactile, temperature, chemical) is addressed to different points of the cerebral cortex, and only the almost simultaneous stimulation of these points of the cerebral cortex establishes a systemic connection between them. These new data correspond to I. P. 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 using electrical appliances showed that the unconditioned stimulus comes to the cerebral cortex in the form of a very generalized flow of ascending excitations, and, obviously, to each cell of the cortex. This means that not a single excitation of the sensory organs that preceded the unconditioned stimulus can “escape” its convergence with the unconditioned excitation. These properties of the unconditioned stimulus strengthen the idea of “convergent closure” of the conditioned reflex.

Cortical representations of unconditioned reactions are 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 be afferent in nature. As is known, I.P. Pavlov considered the cerebral cortex “an isolated afferent section of the central nervous system.”

Complex unconditioned reflexes. I. P. Pavlov identified a special category of unconditioned reflex, into 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 I.P. Pavlov, complex unconditioned reflexes are a function of the “proximal subcortex”. Underneath this general expression refers to the thalamus, hypothalamus and other parts of the interstitial and midbrain. However, later, with the development of ideas about the cortical representations of the unconditioned reflex, this point of view was transferred to the concept of complex unconditioned reflexes. Thus, a complex unconditioned reflex, for example, an emotional discharge, has a specific subcortical part, but at the same time the very course of this complex unconditioned reflex at each individual stage is represented in the cerebral cortex. This point of view of I.P. Pavlov was confirmed by research recent years using the neurography method. 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) represent a “blind force” or “the main source of strength” for cortical cells. The provisions expressed 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 general development, and only in connection with the discovery of the physiological characteristics of the hypothalamus, reticular formation brain stem, it became possible to study this problem in more depth.

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

In the process of studying the unconditioned pain reflex, it was revealed that pain excitation undergoes significant transformations at the level of the brain stem and hypothalamus. From these structures, unconditioned excitation generally covers all areas of the cerebral cortex simultaneously. Thus, along with the mobilization in the cerebral cortex of systemic connections that are characteristic of a given unconditional excitation and form 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 the cortical waveform electrical activity. The conduction of unconditioned painful excitation to the cerebral cortex can be blocked at the level of the brain stem using a special substance - aminazine. After the introduction of this substance into the blood, even a strong damaging (nociceptive) unconditioned 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 embryonic development animals and humans. At different stages of embryogenesis, each stage of structural and functional formation unconditional reflex. The vital functional systems of a newborn are completely consolidated at the time of birth. Individual links of a sometimes complex unconditioned reflex, such as the sucking reflex, involve different parts of the body, often at a considerable distance from each other. Nevertheless, they are selectively united 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 unchangeable adaptive effect of the unconditioned reflex upon application of the corresponding stimulus. This property of an 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 species of animal, then, depending on the characteristics of the conditions of existence of each species of animal, the nature of structural maturation and the final formation of the unconditioned reflex will exactly correspond to the characteristics of the given species.

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

This selective growth of the nervous structures of the unconditioned reflex occurs even more clearly in the development of the human fetus. The very first and clearly visible motor reaction the human fetus is the grasping reflex; it is detected already in the 4th month of intrauterine life and is caused by the application of any hard object to the palm of the fetus. Morphological analysis of all links of this reflex convinces us that, before it is revealed, a number of nerve structures differentiate into mature neurons and unite with each other. Myelination of the nerve trunks related to the finger flexors begins and ends earlier than 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 a consequence of consolidation natural selection and the heredity of those reactions acquired over thousands of years that correspond to repeated environmental factors and are useful for a given species.

There is reason to assert that the most rapid and successful adaptations of the 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. I. A. Bulygina, M., 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 quantitative research 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 collection works, vol. 1-6, M., 1951 - 1952; Petukhov B. N. Closure after loss of basic unconditioned reflexes, Proceedings Center, Institute of Improvements. doctors, vol. 81, p. 54, M., 1965, bibliogr.; S a l h e nko I. N. Hidden periods of myotatic reflexes that ensure motor interactions of people, Physiol. human, vol. 1, Jvft 2, p. 317, 197 5, bibliogr.; Sechenov I. M. Reflexes of the brain, M., 1961; Slonim A.D. Fundamentals of general economic physiology of mammals, p. 72, M,-JI., 1961, bibliogr.; Human Physiology, ed. E. B. Babsky, p. 592, M., 1972; Frankstein S.I. Respiratory reflexes and mechanisms of shortness of breath, M., 1974, bibliogr.; Sh u s t i n N. A. Analysis of unconditioned reflexes in the light of the doctrine of the dominant, Physiol, journal. USSR, vol. 61, JSft 6, p. 855, 1975, bibliogr.; Human reflexes, pathophysiology of motor systems, ed. by J. E. Desment, Basel a. o., 1973; Mechanisms of orienting reactions in man, ed. by I. Ruttkay-Nedecky a. o., Bratislava, 1967.

Human behavior is associated with conditioned-unconditioned reflex activity and represents higher nervous activity, the result of which is a change in the relationship of the organism with the external environment.

In contrast to higher nervous activity, lower nervous activity consists of a set of reactions aimed at unifying and integrating functions within the body.

Higher nervous activity manifests itself in the form of complex reflex reactions carried out with the obligatory participation of the cerebral cortex and the subcortical formations closest to it.

For the first time, the idea of the reflex nature of brain activity was widely and in detail developed by the founder of Russian physiology I.M. Sechenov in his book “Reflexes of the Brain.” The ideological setting of this classic work is expressed in the original title, changed under the influence of censorship: “An attempt to introduce physiological basis into mental processes." Before I.M. Sechenov, physiologists and neurologists did not even dare to raise the question of the possibility of an objective, purely physiological analysis mental processes. The latter remained completely at the mercy of subjective psychology.

The ideas of I. M. Sechenov received brilliant development in the remarkable works of I. P. Pavlov, who opened the path to objective experimental research functions of the cerebral cortex and created a harmonious doctrine of higher nervous activity.

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.

Conditioned reflexes

these are reactions acquired by the body in the process of individual development based on “life experience”
are individual: some representatives of the same species may have them, while others may not
are unstable and, depending on certain conditions, they can develop, gain a foothold or disappear; this is their property and is reflected in their very name
can be formed in response to a wide variety of stimuli applied to various receptive fields
are closed at the level of the cortex. After removing the cerebral cortex, the developed conditioned reflexes disappear and only unconditioned ones remain.
carried out through functional temporary connections

Conditioned reflexes are developed on the basis of unconditioned reflexes. For the formation of a conditioned reflex, it is necessary to combine the time of any change in the external environment and the internal state of the body, perceived by the cerebral cortex, with the implementation of one or another unconditioned reflex. Only under this condition does a change in the external environment or internal state of the body become a stimulus to a conditioned reflex - a conditioned stimulus, or signal. The irritation that causes an unconditioned reflex - unconditioned irritation - must, during the formation of a conditioned reflex, accompany the conditioned irritation and reinforce it.

In order for the clinking of knives and forks in the dining room or the knocking of a cup from which a dog is fed to cause salivation in the first case in a person, in the second case in a dog, it is necessary to re-coincidence of these sounds with food - reinforcement of stimuli that are initially indifferent to salivary secretion by feeding , i.e., unconditional irritation of the salivary glands.

Likewise, the flashing of an electric light bulb in front of the dog’s eyes or the sound of a bell will only cause conditioned reflex flexion of the paw if they are repeatedly accompanied by electrical irritation of the skin of the leg, causing an unconditioned flexion reflex whenever it is used.

Similarly, a child’s crying and his hands pulling away from a burning candle will be observed only if the sight of the candle first coincided at least once with the feeling of a burn.

In all the above examples, external agents that are initially relatively indifferent - the clinking of dishes, the sight of a burning candle, the flashing of an electric light bulb, the sound of a bell - become conditioned stimuli if they are reinforced by unconditioned stimuli. Only under this condition do signals from the external world that are initially indifferent become stimuli. certain type activities.

For the formation of conditioned reflexes, it is necessary to create a temporary connection, a closure between the cortical cells that perceive conditioned stimulation and the cortical neurons that are part of the unconditioned reflex arc.

When conditioned and unconditioned stimulation coincide and combine, a connection is established between different neurons in the cerebral cortex and a process of closure occurs between them.

Unconditioned reflexes

These are innate, hereditary reactions of the body
are specific, i.e. characteristic of all representatives of a given species
relatively constant, as a rule, persist throughout life
carried out in response to adequate stimulation applied to one specific receptive field
closes at the level of the spinal cord and brainstem
are carried out through a phylogenetically fixed, anatomically expressed reflex arc.

It should be noted, however, that in humans and monkeys, who have high degree 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 long after birth, but they necessarily appear under the condition normal development nervous system.

The entire set of unconditioned and conditioned reflexes formed on their basis is accepted according to their functional significance divided into a number of groups.

By receptor
1. Exteroceptive reflexes
  - visual
  - olfactory
  - flavoring, etc.
2. Interoreceptive reflexes- reflexes in which the conditioned stimulus is irritation of the receptors of internal organs by changes in the chemical composition, temperature of internal organs, pressure in hollow organs and blood vessels
By effector trait, i.e. by those effectors that respond to stimulation
1. autonomic reflexes
  - food
  - cardiovascular
  - respiratory, etc.
2. somato-motor reflexes- manifested in movements of the whole organism or its individual parts in response to a stimulus
  - defensive
According to biological significance
1. Food
  - reflex act of swallowing
  - reflexive act of chewing
  - reflex act of sucking
  - reflex act of salivation
  - reflex act of secretion of gastric and pancreatic juice, etc.
2. Defensive- reactions to eliminate damaging and painful stimuli
3. Genital- reflexes associated with sexual intercourse; This group also includes the so-called parental reflexes associated with feeding and nursing the offspring.
4. Stato-kinetic and locomotor- reflex reactions of maintaining a certain position and movement of the body in space.
5. Reflexes for maintaining homeostasis
  - thermoregulation reflex
  - breathing reflex
  - cardiac reflex
  - vascular reflexes that help maintain constant blood pressure, etc.
6. Orienting reflex- reflex to novelty. It occurs in response to any fairly quickly occurring fluctuation in the environment and is expressed externally in alertness, listening to a new sound, sniffing, turning the eyes and head, and sometimes the whole body towards the emerging light stimulus, etc. The implementation of this reflex provides better perception of the acting agent and has important adaptive significance.
  I. P. Pavlov figuratively called the indicative reaction the “what is it?” reflex. This reaction is innate and does not disappear when complete removal cerebral cortex in animals; it is also observed in children with underdeveloped cerebral hemispheres - anencephals.

The difference between the orienting reflex and other unconditioned reflex reactions is that it fades away relatively quickly with repeated applications of the same stimulus. This feature of the orientation reflex depends on the influence of the cerebral cortex on it.

The above classification of reflex reactions is very close to the classification of various instincts, which are also divided into food, sexual, parental, and defensive. This is understandable due to the fact that, according to I.P. Pavlov, instincts are complex unconditioned reflexes. Their distinctive features is the chain nature of the reactions (the end of one reflex serves as the trigger for the next) and their dependence on hormonal and metabolic factors. Thus, the emergence of sexual and parental instincts is associated with cyclical changes in the functioning of the gonads, and the food instinct depends on those metabolic changes that develop in the absence of food. One of the features of instinctive reactions is also that they are characterized by many properties of the dominant.

The reflex component is a reaction to irritation (movement, secretion, change in breathing, etc.).

Most unconditioned reflexes are complex reactions, which includes several components. So, for example, with an unconditioned defensive reflex, caused in a dog by strong electrocutaneous irritation of the limb, along with defensive movements, breathing also increases and increases, cardiac activity accelerates, vocal reactions appear (squealing, barking), the blood system changes (leukocytosis, platelets and etc.). The food reflex also distinguishes between its motor (grasping food, chewing, swallowing), secretory, respiratory, cardiovascular and other components.

Conditioned reflexes, as a rule, reproduce the structure of the unconditioned reflex, since the conditioned stimulus excites the same nerve centers as the unconditioned one. Therefore, the composition of the components of the conditioned reflex is similar to the composition of the components of the unconditioned reaction.

Among the components of a conditioned reflex, there are main, specific for a given type of reflex, and secondary components. In the defensive reflex the main component is the motor component, in the food reflex the main component is the motor and secretory ones.

Changes in respiration, cardiac activity, and vascular tone that accompany the main components are also important for the animal’s holistic response to a stimulus, but they play, as I. P. Pavlov said, “purely official role". Thus, increased and increased respiration, increased heart rate, increased vascular tone, caused by a conditioned defensive stimulus, contribute to increased metabolic processes in skeletal muscles and thereby create optimal conditions for the implementation of protective motor reactions.

When studying conditioned reflexes, the experimenter often chooses one of its main components as an indicator. That is why they talk about conditioned and unconditioned motor or secretory or vasomotor reflexes. It is necessary, however, to take into account that they represent only individual components of the body’s holistic reaction.

The 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 effects and so on.

The adaptive significance of conditioned reflexes is also manifested in the fact that the precedence of conditioned stimulation by an unconditioned one strengthens the unconditioned reflex and accelerates its development.

Animal behavior is different shapes external, mainly motor activity aimed at establishing vital important connections organism with the environment. Animal behavior consists of conditioned, unconditioned reflexes and instincts. Instincts are complex unconditional reactions, which, being congenital, appear only during certain periods of life (for example, the instinct of nesting or feeding offspring). Instincts play a leading role in the behavior of lower animals. However, the higher an animal is at the evolutionary level, the more complex and varied its behavior, the more perfect and subtle it adapts to environment and the greater the role that conditioned reflexes play in his behavior.

The environment in which animals exist is very variable. Adaptation to the conditions of this environment through conditioned reflexes will be subtle and accurate only if these reflexes are also changeable, that is, conditioned reflexes unnecessary in the new environmental conditions will disappear, and new ones will form in their place. The disappearance of conditioned reflexes occurs due to inhibition processes.

A distinction is made between external (unconditioned) inhibition of conditioned reflexes and internal (conditioned) inhibition.

External inhibition of conditioned reflexes 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.

So, if, before the onset of a conditioned food reflex, a extraneous sound or some foreign smell appears, or the lighting changes sharply, the conditioned reflex decreases or even disappears completely. This is explained by the fact that any new stimulus evokes an orienting reflex in the dog, which inhibits the conditioned reaction.

Extraneous irritations associated with the activities of others also have an inhibitory effect. nerve centers. For example, painful stimulation inhibits food conditioned reflexes. Irritations emanating from internal organs can also act in the same way. Bladder overflow, vomiting, sexual arousal, and inflammation in any organ cause inhibition of conditioned food reflexes.

Extremely strong or long-acting extraneous stimuli can cause extreme inhibition of reflexes.

Internal inhibition of conditioned reflexes occurs in the absence of reinforcement by an unconditioned stimulus of the received signal.

Internal inhibition does not occur immediately. As a rule, repeated use of a non-reinforced signal is required.

The fact that this is inhibition of the conditioned reflex, and not its destruction, is evidenced by the restoration of the reflex the next day, when the inhibition has passed. Various diseases, overwork, and overstrain cause a weakening of internal inhibition.

If a conditioned reflex is extinguished (not reinforced with food) for several days in a row, it may disappear completely.

There are several types of internal inhibition. The form of inhibition discussed above is called extinction inhibition. This inhibition underlies the disappearance of unnecessary conditioned reflexes.

Another type is differentiated (discriminating) inhibition.

A non-reinforced conditioned stimulus causes inhibition in the cortex and is called an inhibitory stimulus. Using the described technique, it was possible to determine the discriminative ability different organs feelings in animals.

The phenomenon of disinhibition. It is known that extraneous stimuli cause inhibition of conditioned reflexes. If an extraneous stimulus occurs during the action of an inhibitory stimulus, for example, during the action of a metronome at a frequency of 100 times per minute, as in the previous case, then this will cause the opposite reaction - saliva will flow. I.P. Pavlov called this phenomenon disinhibition and explained it by the fact that an extraneous stimulus, causing an orienting reflex, inhibits any other process that is currently occurring in the centers of the conditioned reflex. If the inhibition process is inhibited, then all this leads to excitation and implementation of the conditioned reflex.

The phenomenon of disinhibition also indicates the inhibitory nature of the processes of discrimination and extinction of conditioned reflexes.

The meaning of conditional inhibition very large. Thanks to inhibition, a much better correspondence of the body's reaction to external conditions is achieved, its adaptation to the environment is more perfect. The combination of two forms of a single nervous process- excitation and inhibition - and their interaction enable the body to navigate in various complex situations, are the conditions for the analysis and synthesis of stimuli.

Reflex- the body's response is not external or internal stimulation, 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- This innate reflexes, which are inherited by offspring from their parents and persist throughout a person’s life. The arcs of unconditioned reflexes pass through 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 congenital, but also more complex shapes behaviors that 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, repetition 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 irritations from the surrounding world, to which we were indifferent, can now become vitally important. 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 highlight 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, attention are freed from performing those operations that have become automated and become skills Everyday life. Most successful path Mastering skills means 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.