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

Without conditioned reflexes- congenital, 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.

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 certain change in the internal state of the body. In the laboratory of I.P. Pavlov, the flashing of an electric light bulb, the bell, the gurgling of water, skin irritation, gustatory, 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 schedule, 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. Now let's back up the sound of the bell with 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). Cuts in the 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 main role refers 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 nervous structures that are involved 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 has 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 takes place in the wolf’s cerebral cortex: motor and food conditioned reflexes are 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. External world acts on the body not by single stimuli, but usually by 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 assimilation of knowledge, skills, and 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 for many 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.

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 devices. A reflex is the body’s response 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, like physiological one, 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 higher nervous activity of any animal organism is based on conditioned and unconditioned reflexes.

Unconditioned reflexes are very diverse; they are the basis instinctive activity body. Unconditioned reflexes are innate and do not require special training. 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. IP Pavlov called a conditioned reflex a temporary connection between a stimulus and a response activity that occurs in the body under certain conditions. Therefore, in the literature, instead of the term “conditioned reflex,” the term “temporary connection” is often used, which also 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 of various muscle groups - occur in response to tactile or pain stimulation 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 with sudden changes in the external environment surrounding the animal, or with internal changes in its 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 at certain, usually early, stages of 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 cortex big brain. 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 species active work;

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 protective (extraordinary) inhibition in nerve cells, 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: restored physical activity, autonomic reactions, electroencephalogram rhythm. Excitation covers a large part of the cerebral cortex and the formation of the limbic system. Result - 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 effects, 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 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 in 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.

The main form of activity of the 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, biological nature which still 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 lemon), the food focus of excitation has a dominant (main) significance and “attracts” excitation from the visual center.

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

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

Reflex- this is the body's response to irritation of receptors, carried out nervous system. The path along which the nerve impulse passes during the implementation of the reflex is called.

The concept of “reflex” was introduced by Sechenov, he believed that “reflexes form the basis of the nervous activity of humans and animals.” Pavlov divided reflexes into conditioned and unconditioned.

Comparison of conditioned and unconditioned reflexes

Development of a conditioned reflex

Conditional (indifferent) the stimulus must precede unconditional(causing an unconditioned reflex). For example: a lamp is lit, after 10 seconds the dog is given meat.

Inhibition of conditioned reflexes

Conditional (non-reinforcement): the lamp lights up, but the dog is not given meat. Gradually, salivation when the lamp is turned on stops (the conditioned reflex fades).

Unconditional: During the action of a conditioned stimulus, a powerful unconditioned stimulus arises. For example, when the lamp is turned on, the bell rings loudly. No saliva is produced.

Choose one, the most correct option. The centers of conditioned reflexes, in contrast to unconditioned ones, are located in humans in
1) cerebral cortex
2) medulla oblongata
3) cerebellum
4) midbrain

Answer

Choose one, the most correct option. Salivation in a person at the sight of a lemon is a reflex
1) conditional
2) unconditional
3) protective
4) approximate

Answer

Choose three options. The peculiarity of unconditioned reflexes is that they




5) are congenital
6) are not inherited

Answer

Choose three correct answers out of six and write down the numbers under which they are indicated. Unconditioned reflexes that ensure life activity human body,
1) are developed in the process of individual development
2) formed in the process of historical development
3) are present in all individuals of the species
4) strictly individual
5) formed under relatively constant environmental conditions
6) are not congenital

Answer

Choose three correct answers out of six and write down the numbers under which they are indicated. The peculiarity of unconditioned reflexes is that they
1) arise as a result of repeated repetition
2) are a characteristic characteristic of an individual individual of the species
3) are genetically programmed
4) are characteristic of all individuals of the species
5) are congenital
6) build skills

Answer

Choose one, the most correct option. What are the features of spinal reflexes in humans and mammals?
1) acquired during life
2) are inherited
3) are different in different individuals
4) allow the organism to survive in changing environmental conditions

Answer

Choose one, the most correct option. The extinction of a conditioned reflex when it is not reinforced by an unconditioned stimulus is
1) unconditional inhibition
2) conditioned inhibition
3) rational action
4) conscious action

Answer

Choose one, the most correct option. Conditioned reflexes of humans and animals provide
1) adaptation of the body to constant environmental conditions
2) adaptation of the body to the changing external world
3) development of new motor skills by organisms
4) discrimination by animals of the trainer’s commands

Answer

Choose one, the most correct option. A baby's reaction to a bottle of milk is a reflex that
1) inherited
2) is formed without the participation of the cerebral cortex
3) acquired during life
4) persists throughout life

Answer

Choose one, the most correct option. When developing a conditioned reflex, the conditioned stimulus must
1) act 2 hours after unconditional
2) come immediately after the unconditional
3) precede the unconditional
4) gradually weaken

Answer

1. Establish a correspondence between the meaning of the reflex and its type: 1) unconditional, 2) conditional. Write numbers 1 and 2 in the correct order.
A) provides instinctive behavior
B) ensures the body’s adaptation to conditions environment, in which many generations of this species lived
C) allows you to gain new experience
D) determines the behavior of the organism in changed conditions

Answer

2. Establish a correspondence between the types of reflexes and their characteristics: 1) conditional, 2) unconditional. Write numbers 1 and 2 in the order corresponding to the letters.
A) are congenital
B) adaptation to new emerging factors
C) reflex arcs are formed in the process of life
D) are the same in all representatives of the same species
D) are the basis of learning
E) are constant, practically do not fade during life

Answer

Choose one, the most correct option. Conditioned (internal) inhibition
1) depends on the type of higher nervous activity
2) appears when a stronger stimulus occurs
3) causes the formation of unconditioned reflexes
4) occurs when the conditioned reflex fades

Answer

Choose one, the most correct option. The basis of nervous activity in humans and animals is
1) thinking
2) instinct
3) excitement
4) reflex

Answer

1. Establish a correspondence between the examples and types of reflexes: 1) unconditional, 2) conditional. Write numbers 1 and 2 in the correct order.
A) withdrawing a hand from the fire of a burning match
B) a child crying at the sight of a man in a white coat
C) a five-year-old child reaching out to the sweets he saw
D) swallowing pieces of cake after chewing them
D) salivation at the sight of a beautifully set table
E) downhill skiing

Answer

2. Establish a correspondence between the examples and the types of reflexes that they illustrate: 1) unconditional, 2) conditioned. Write numbers 1 and 2 in the order corresponding to the letters.
A) sucking movements of the child in response to touching his lips
B) constriction of the pupil illuminated by the bright sun
C) performing hygiene procedures before bed
D) sneezing when dust enters the nasal cavity
D) secretion of saliva to the clink of dishes when setting the table
E) roller skating

Answer

© D.V. Pozdnyakov, 2009-2019