The meaning of conditioned and unconditioned reflexes. Congenital and acquired forms of behavior

Abstract on the topic:

"Conditioned and unconditioned reflexes"

Donetsk 2010

Introduction.

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

2. Classification of unconditioned reflexes.

3. The mechanism of formation of conditioned reflexes.

4. Conditions for the formation of conditioned reflexes.

5. Classification of conditioned reflexes.

Conclusion.

List of used literature.

Introduction.

The adaptation of animals and humans to changing conditions of existence in the external environment is ensured by the activity of the nervous system and is realized through reflex activity. In the process of evolution, hereditarily fixed reactions (unconditioned reflexes) arose that combine and coordinate the functions of various organs and carry out adaptation of the body. In humans and higher animals, in the process of individual life, qualitatively new reflex reactions arise, which I. P. Pavlov called conditioned reflexes, considering them the most perfect form of adaptation. A reflex is 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 an 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 of the instinctive activity of the body. Unconditioned reflexes are innate; they 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, and elbow reflexes - when the receptors of the tendons of certain muscles are irritated, the pupillary - when a sharp change in illumination acts on the retina, etc. With irritation These reactions are not evoked by other receptive fields.

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

During the growth and development of the organism, the system of unconditional reflex connections still turns out to be limited, inert, and unable to provide sufficiently mobile adaptation reactions corresponding to fluctuations in the external and internal environment. More perfect adaptation of the body to constantly changing conditions of existence occurs thanks to conditioned reflex, i.e., individually acquired reactions. Conditioned reflex mechanisms of the brain are related to all types of activity of the body (to somatic and vegetative functions, to behavior), providing adaptive reactions aimed at maintaining the integrity and stability of the “organism-environment” system. I. P. Pavlov called 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 different 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 the organs of the digestive system and 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 cerebral cortex. The closure of the temporary connection is based on the process of dominant interaction between excited centers. Impulses caused by an indifferent (conditioned) signal from any part of the skin and other sensory organs (eye, ear) enter the cerebral cortex and ensure the formation of a focus of excitation in it. If, after an indifferent signal, food reinforcement (feeding) is given, then a more powerful second focus of excitation arises in the cerebral cortex, to which the previously arisen and irradiating excitation along the cortex is directed. Repeated combination in experiments of a conditioned signal and an unconditioned stimulus facilitates the passage of impulses from the cortical center of the indifferent signal to the cortical representation of the unconditioned reflex - synaptic facilitation (blazing the path) - dominant. The conditioned reflex first becomes a dominant, and then a conditioned reflex.

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

4. Conditions for the formation of conditioned reflexes.

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

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

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

3) vigorous state of the body;

4) absence of other types of active activity;

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

6) suprathreshold intensity of the conditioned stimulus.

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

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

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

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

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

The emergence and consolidation of a conditioned reflex connection occurs at a certain level of excitation of the nerve centers. In this regard, the strength of the conditioned signal should be above the threshold, but not excessive. To weak stimuli, conditioned reflexes are not developed at all or are formed slowly and are unstable. Excessively strong stimuli cause the development of 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: motor activity, autonomic reactions, and electroencephalogram rhythm are restored. Excitation covers a large part of the cerebral cortex and the formation of the limbic system. The result is cognitive activity.

Differences between the orienting reflex and other conditioned reflexes:

1) innate reaction of the body;

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

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

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

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

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

3) interoceptive – affect mood and performance.

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

1) somatic (motor);

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

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

Artificial – conditioned reflexes to such 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 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.

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, 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. The conditioned reflex separation of saliva, gastric and pancreatic juices by sight, smell, and meal times creates better conditions for digesting food even 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, 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 salivation in a person only if this clinking is supported by 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 sounding 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 pathways also play 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, that is, 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 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 through single stimuli, but usually through 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 us to pay special attention to 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.

Reflex- This is the body’s response to irritation of receptors, carried out by the nervous system. The path along which a nerve impulse travels during a reflex is called a reflex arc.

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.

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.

MORE INFORMATION: Reflex, reflex arc, conditioned and unconditioned reflexes, Development and inhibition of conditioned reflexes
TASKS PART 2: Reflexes

Tests and assignments

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

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

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



5) are congenital
6) are not inherited

Choose three correct answers out of six and write down the numbers under which they are indicated. Unconditioned reflexes that ensure the vital functions of the 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

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

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

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

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

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

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

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 adaptation of the organism to the environmental conditions 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

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

3. Establish a correspondence between the characteristics and types of reflexes: 1) conditional, 2) unconditional. Write numbers 1 and 2 in the order corresponding to the letters.
A) acquired in the course of life
B) are characteristic of all representatives of this species
C) unstable, capable of fading
D) provide adaptation to changing environmental conditions
D) permanent, lasting throughout life
E) are passed on to offspring over generations

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

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

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

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

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Unconditioned reflexes- These are innate, hereditarily transmitted reactions of the body. Conditioned reflexes- these are reactions acquired by the body in the process of individual development on the basis of “life experience”.

Unconditioned reflexes are specific, i.e.

Unconditioned and conditioned reflexes

characteristic of all representatives of this species. Conditioned reflexes are individual: some representatives of the same species may have them, while others may not.

Unconditioned reflexes are relatively constant; conditioned reflexes are not constant and, depending on certain conditions, they can be developed, consolidated or disappear; This is their property and is reflected in their very name.

Unconditioned reflexes are carried out in response to adequate stimulation applied to one specific receptive field.

Conditioned reflexes can be formed to a wide variety of stimuli applied to various receptive fields.

In animals with a developed cerebral cortex, conditioned reflexes are a function of the cerebral cortex. After removing the cerebral cortex, the developed conditioned reflexes disappear and only unconditioned ones remain. This indicates that in the implementation of unconditioned reflexes, in contrast to conditioned ones, the leading role belongs to the lower parts of the central nervous system - the subcortical nuclei, brain stem and spinal cord. It should be noted, however, that in humans and monkeys, who have a high degree of corticalization of functions, many complex unconditioned reflexes are carried out with the obligatory participation of the cerebral cortex. This is proven by the fact that its lesions in primates lead to pathological disorders of unconditioned reflexes and the disappearance of some of them.

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

Conditioned reflexes are developed on the basis of unconditioned reflexes. For the formation of a conditioned reflex, it is necessary to combine in time some kind of change in the external environment or 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 a 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 the initially indifferent signals of the external world become stimuli for a certain type of activity.

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.

Main article: Higher nervous activity

Reflex- This is the body’s response to external and internal irritations through the nervous system. The reflex is a basic and specific function of the central nervous system. All activities of the human body are carried out through reflexes. For example, feeling pain, moving limbs, breathing, blinking and other actions are essentially reflexes.

Reflex arc

Each reflex has its own reflex arc, which consists of the following five parts:

• a receptor located in tissues and organs and perceiving irritations from the external and internal environment;
• sensitive nerve fiber, which transmits impulses generated when the receptor is excited to the nerve center;
• nerve center, which consists of sensitive, intercalary, motor nerve cells located in the brain;
• motor nerve fiber, which transmits the excitation of the nerve center to the working organ;
• working organ - muscles, glands, blood vessels, internal organs and others.

Types of reflexes

Depending on which part of the central nervous system is involved in the manifestation of the body’s response to stimuli, two types of reflexes are distinguished: unconditioned and conditioned.

Unconditioned reflexes

see Normal reflexes

The lower parts of the central nervous system—the nerve centers of the spinal cord, medulla oblongata, midbrain, and diencephalon—are involved in the formation of unconditioned reflexes. Unconditioned reflexes are innate, since their nerve pathways already exist in a newborn child. These reflexes serve to ensure important life processes in the human body. For example, chewing food (baby suckling), swallowing, digestion, excretion of feces and urine, breathing, blood circulation and others. Unconditioned reflexes are permanent, that is, they do not change (do not disappear) during a person’s life. Their number and type are almost the same in all people. These reflexes are inherited.

Conditioned reflexes

The centers of conditioned reflexes are located in the cortex of the large hemispheres of the brain. At the birth of a child, these reflexes are absent; they are formed during a person’s life. The neural pathways of conditioned reflexes are also absent at birth; they are formed subsequently as a result of upbringing, training and life experience.

Formation of conditioned reflexes

Conditioned reflexes are formed on the basis of unconditioned ones. For the formation of a conditioned reflex, it is necessary that the unconditioned stimulus act first, and then the conditioned stimulus. So, for example, to develop a conditioned salivary reflex in a dog, first turn on an electric light bulb or a bell as a conditioned one, then give it food as an unconditioned stimulus. When this experience is repeated several times, a temporary connection is formed between the centers of nutrition and vision or hearing in the brain. As a result, just turning on an electric light bulb or a bell will cause the dog to salivate (even in the absence of food), that is, a salivary conditioned reflex will appear in response to a flash of light or a bell (Fig. 70). In this case, the flash of an electric light bulb excites the visual center in the ordinal part of the brain. This excitation, through a temporary connection, causes excitation of the subcortical food center. This, in turn, causes stimulation of the food center located in the medulla oblongata, and as a result of increased activity of the salivary glands through nerve fibers, salivation begins. The figure shows, first, under the influence of light, the excitation of the subcortical visual center, its spread through a temporary connection to the subcortical food center, and from it to the subcortical center in the medulla oblongata, and finally, its entry into the salivary glands, causing salivation. Material from the site http://wiki-med.com

Inhibition of conditioned reflexes

It is known that during the implementation of the formed conditioned reflex, if some strong external stimulus suddenly affects a dog (or a person), then strong excitement occurs in the nerve center of the brain. This excitation by induction inhibits the center of the conditioned reflex and the reflex temporarily stops. Thus, in the figure you can see how, under the influence of the light of an electric lamp, a conditioned reflex of salivation appears in a dog; As a result of an additional strong stimulus - a bell - the auditory center is excited, the centers of conditioned reflexes are inhibited and salivation stops.

Pathological reflexes

§1. Conditioned and unconditioned reflexes

Pathological reflexes

Reflex Research

see Reflex Research

In clinical practice, normal segmental as well as pathological reflexes are examined. The course of segmental processes is influenced by suprasegmental structures, therefore segmental reflexes are often disrupted with certain suprasegmental lesions, and in the implementation of a number of pathological reflexes suprasegmental disorders are of decisive importance.

On this page there is material on the following topics:

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Questions for this article:

• What is the difference between unconditioned and conditioned reflexes?

• How does inhibition of a conditioned reflex occur?

Material from the site http://Wiki-Med.com

Classification of reflexes. What types of reflexes are there?

The functioning of the nervous system is based on the inextricable unity of congenital and acquired forms of adaptation, i.e. unconditioned and conditioned reflexes.

Unconditioned reflexes are innate, relatively constant species-specific reactions of the body, carried out through the nervous system in response to the action of certain stimuli. They ensure the coordinated activity of various functional systems of the body, aimed at maintaining its homeostasis and interaction with the environment. Examples of simple unconditioned reflexes include knee, blink, swallow and others.

There is a large group of complex unconditioned reflexes: self-preservation, food, sexual, parental (caring for offspring), migration, aggressive, locomotor (walking, running, flying, swimming), etc. Such reflexes are called instincts. They underlie the innate behavior of animals and represent complexes of stereotypical species-specific motor acts and complex forms of behavior.

A conditioned reflex is a reaction of the body acquired during an individual’s life, carried out due to the formation in the higher parts of the central nervous system of temporary variable reflex pathways in response to the action of any signal stimulus, for the perception of which there is a responsible receptor apparatus. An example is the classical conditioned reflex of I.P. Pavlov - the release of saliva by a dog to the sound of a bell, which had previously been connected several times with feeding animals. A conditioned reflex is formed as a result of a combination of the action of two stimuli - conditioned and unconditioned.

An unconditioned stimulus is a stimulus that causes an unconditioned reflex to occur. For example, turning on a bright light causes the pupil to constrict; the action of an electric current causes the dog to withdraw its paw.

A conditioned stimulus is any neutral stimulus that, after repeated combination with an unconditioned stimulus, acquires a signal value. Yes, the sound of the bell, which is repeated, leaves the animal indifferent to it. However, when the sound of the bell is combined with feeding the animal (an unconditioned stimulus), then after several repetitions of both stimuli the bell becomes a conditioned stimulus, alerting the animal to the presentation of food and causing it to salivate.

Conditioned reflexes can be classified according to receptor characteristics, the nature of the conditioned stimulus, the time of action of the conditioned and unconditioned stimuli, and the effector characteristic.

Based on receptor characteristics, conditioned reflexes are divided into external and interoceptive.

• Exteroceptive reflexes are produced in response to visual, auditory, olfactory, gustatory, skin-mechanical stimuli, etc. They play a major role in the interaction of the organism with the environment, and therefore are formed and specialized relatively easily.
• Interoceptive conditioned reflexes are formed by combining stimulation of the receptors of internal organs with any unconditioned reflex. They form much more slowly and are diffuse in nature.

According to the nature of the conditioned stimulus, conditional reflexes are divided into natural and artificial. Natural reflexes are formed under the influence of natural unconditioned stimuli, for example, salivation to the smell or sight of food. Conditioned reflexes are called artificial. Artificial reflexes are often used in scientific experiments, since their parameters (strength, duration, etc.) can be arbitrarily adjusted.

Based on the time of action of conditioned and unconditioned stimuli, they are distinguished existing and trace conditioned reflexes. Existing conditioned reflexes are formed when reinforcement is given within the duration of the conditioned stimulus. Trace reflexes are conditioned reflexes that are formed in the event of the action of a reinforcing stimulus after the end of the conditioned signal. A special type of trace conditioned reflexes are timed reflexes, which are formed under the condition of regular repetition of an unconditioned stimulus at certain intervals.

According to the effector sign, conditional reflexes are divided into vegetative and somatomovement. Autonomic ones include food, cardiovascular, excretory, sexual and similar conditioned reflexes.

Reflex (biology)

An example of an autonomic conditioned reflex is the classic salivary reflex. Somatomotive include protective, food-producing conditioned reflexes, as well as complex behavioral reactions.

In real life, conditioned reflexes are usually formed not to one, but to several stimuli, so they can be divided into simple and complex(complex). Complex conditioned reflexes can be simultaneous or sequential, depending on the combination and sequence of action of a set of stimuli.

Unconditioned reflexes constitute the lower nervous activity, ensuring the implementation of various motor acts of life support, as well as the regulation of the functions of internal organs.

The elements of higher nervous and mental activity in the human animal are instincts and conditioned reflexes (learning reactions), which manifest themselves in the form of behavioral reactions.

Topic: “Development of a conditioned blink reflex”

Goal of the work: Master the technique of developing a conditioned blink reflex.

Equipment: arc-shaped stand, tripod, rubber tube with bulb, whistle.

Mechanical irritation of the cornea and sclera causes an unconditioned blink reflex. On the basis of this unconditioned stimulus, a conditioned blink reflex can be developed - a bell is used as a conditioned stimulus, and an intermittent stream of air is used as an unconditioned stimulus.

Progress:

1. Development of an unconditioned blink reflex. The subject's chin is placed on an arched stand mounted on a tripod. The end of the tube conducting air from the cylinder is placed at eye level at a distance of 5-10 cm.

Conditioned and unconditioned reflexes

Select the strength of the air stream that causes an unconditioned protective reflex of blinking. If the reflex is not evoked, repeat the experiment, changing the position of the metal tube.

Development of a conditioned blink reflex. The experimenter with a whistle stands behind the subject - his task is to use the whistle to produce a conditioned stimulus (whistle). The second experimenter continues to squeeze the bulb and apply a stream of air (unconditioned stimulus). When giving a sound signal, you must immediately press the pear. After 1-2 minutes, repeat this combination of stimuli, while maintaining the same delivery interval between them. After 8-9 combinations, give a sound signal without reinforcing it with an unconditioned stimulus (a stream of air) - a conditioned blink reflex will appear.

3. Draw conclusions based on the results of the experiment. Draw a diagram of the unconditioned and conditioned blink reflex. An example of a conditioned blink reflex is this diagram:

Rice. 1. Scheme of a conditioned blink reflex: 1- receptors of the organ of hearing, 2- afferent pathway (auditory nerve), 3- nerve center, 4- efferent pathway (oculomotor nerve), 5- ciliary muscle of the eye.

Control questions:

1. What is a reflex?

2. What types of reflexes do you know?

3. What are unconditioned reflexes?

4. What are conditioned reflexes?

5. What conditions must be observed when developing conditioned reflexes? In what order should conditioned and unconditioned stimuli be applied?

6. What is the essence of the mechanism for the development of conditioned reflexes?

7. How many links does the reflex arc include? Reflex ring?

8. What types of receptors do you know by location?

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Conditioned reflex, definition, classification of conditioned reflexes.

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

Classification of conditioned reflexes

Conditioned reflexes, as well as unconditioned ones, can be classified according to biological modality - food, drink, defensive;

Depending on the nature of the relationship between signal, conditioned and unconditioned stimuli, conditioned reflexes are divided into natural and artificial. Natural conditioned reflexes are developed to agents that, under natural conditions, are a property of the unconditioned stimulus and act together with the stimulus that causes the unconditioned reflex (for example, the type of food, its smell, etc.). All other conditioned reflexes are artificial, i.e. are produced in response to agents that are not normally associated with the action of an unconditioned stimulus, for example, the food salivary reflex to a bell.

Based on their effector characteristics, conditioned reflexes are divided into secretory, motor, cardiac, vascular, etc.

Based on their role in the implementation of goal-directed behavior, conditioned reflexes are divided into preparatory and executive.

5. If you develop a strong conditioned food reflex, for example, to light, then such a reflex is a conditioned reflex of the first order. On its basis, a second-order conditioned reflex can be developed; for this, a new, previous signal, for example a sound, is additionally used, reinforcing it with a first-order conditioned stimulus (light).

As a result of several combinations of sound and light, the sound stimulus also begins to cause salivation. Thus, a new, more complex indirect time connection arises. It should be emphasized that the reinforcement for a conditioned reflex of the second order is precisely the conditioned stimulus of the first order, and not the unconditioned stimulus (food), since if both light and sound are reinforced with food, then two separate conditioned reflexes of the first order will arise. With a sufficiently strong conditioned reflex of the second order, a conditioned reflex of the third order can be developed. To do this, a new stimulus is used, for example, touching the skin. In this case, the touch is reinforced only by a second-order conditioned stimulus (sound), the sound excites the visual center, and the latter excites the food center. An even more complex temporal relationship arises. Higher order reflexes (4, 5, 6, etc.) are developed only in primates and humans.

CONDITIONED AND UNCONDITIONED REFLEXES

Based on the nature of the relationship of an animal or a person to an unconditioned stimulus, on the basis of which a conditioned reflex is developed, conditioned reflexes are divided into positive and negative. Positive conditioned reflexes bring people closer to the unconditioned stimulus. Negative catch reflexes either move away from him or prevent him from getting closer.

7. Depending on the duration of the period of isolated action of the conditioned signal (PID), conditioned reflexes are divided into coincident (PID = from 0.5 to 3.0 sec.), short-delayed (PID = from 3.0 to 30 sec.), normally delayed ( PID = from 30 to 60 sec.), delayed (PID = more than 60 sec.). The period of isolated action is the period of time from the beginning of the action of the conditioned signal to the moment of action of the unconditioned stimulus.

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The outstanding Russian physiologist I.M. Sechenov was the first to express the idea of ​​a connection between human consciousness and thinking and the reflex activity of his brain. This idea was developed and convincingly confirmed in numerous experiments by I.P. Pavlova. Therefore I.P. Pavlov is considered the creator of the doctrine of higher nervous activity.

Higher nervous activity- these are the functions of the cerebral cortex and the nearest subcortical formations, where temporary nerve connections (conditioned reflexes) are developed anew, ensuring the most subtle and perfect individual adaptation of the body to changing environmental conditions.

UNCONDITIONED AND CONDITIONED REFLEXES

Higher nervous activity is reflexive in nature. Higher animals and humans have unconditioned and conditioned reflexes. Their specificity is as follows.

Unconditioned reflexes ensuring the maintenance of vital functions in relatively constant environmental conditions, are inherent in a person from birth. These include food (sucking, swallowing, salivation, etc.), defensive (coughing, blinking, withdrawing a hand, etc.), reproduction (feeding and caring for offspring), respiratory, etc.

Conditioned reflexes are developed on the basis of unconditioned ones under the influence of a conditioned stimulus. They provide a more perfect adaptation of the body to changing environmental conditions. They help to find food by smell, avoid danger, navigate, etc.

Meaning of the word. In humans, conditioned reflexes can be formed not only as in animals, on the basis of the first signal system, when the conditioned stimuli are directly objects of the external world, but also on the basis of the second (speech) signal system, when the conditioned stimuli are words expressing concepts about objects and phenomena . Conditioned reflexes are the physiological basis of technical processes, the basis of thinking. The word is a kind of irritant for many conditioned reflexes. For example, just talking about food or describing it can cause a person to salivate.

Human consciousness is associated with the activity of the cerebral cortex. This has been convincingly proven by numerous experiments by I.P. Pavlov, as well as by the study of diseases and dysfunctions of the brain.

The teachings of I. P. Pavlov on the higher nervous activity of man convincingly proved the inconsistency and anti-scientific nature of religious ideas about the “soul”.

Inhibition of conditioned reflexes. When environmental conditions change, previously developed conditioned reflexes fade away and new ones are formed. I.P. Pavlov distinguished two types of inhibition of conditioned reflexes.

External braking occurs when the body is exposed to an irritant that is stronger than the previous one. At the same time, a new focus of excitation is formed in the cerebral cortex. For example, in a dog, the conditioned salivary reflex developed in response to light (see “Digestion”) is inhibited under experimental conditions by a stronger stimulus - the sound of a bell. The latter causes strong stimulation in the auditory zone of the cerebral cortex. Initially, it generates inhibition of neighboring areas, and then spreads to the visual area. Therefore, excitation cannot be carried out through the neurons located in it and the arc of the previous conditioned reflex is interrupted.

Internal inhibition occurs in the arc of a conditioned reflex when the conditioned stimulus ceases to receive reinforcement from the unconditioned stimulus and the temporary connections formed in the cortex are gradually inhibited. When conditioned reflexes are repeated in the same sequence, dynamic stereotypes are formed that make up habits and skills.

Hygiene of physical and mental work. The activity of the body depends on the state of the central nervous system. Overwork leads to disruption of the vital functions of the body, reduces perception, attention, memory and performance.

During monotonous physical labor, only one muscle group works and only one part of the central nervous system is excited, which leads to its fatigue.

To avoid overwork, it is useful to perform industrial exercises during breaks, which involve other muscles. This, in turn, leads to the excitation of new areas of the cerebral cortex, inhibition of previously working areas, their rest and restoration of performance.

Mental work also causes fatigue in the central nervous system. The best rest for this is gymnastics or other physical activity.

The daily routine is of great importance in the formation of conditioned reflexes. When followed, a person develops many important conditioned reflexes that stimulate the better functioning of various organ systems and prevent their overwork.

The alternation of physical and mental labor, rationalization of work, adherence to a daily routine, and active rest are of paramount importance to protect the central nervous system from overwork.

Sleep gives the most complete rest to the central nervous system. The alternation of sleep and wakefulness is a necessary condition for human existence. I.P. Pavlov experimentally proved that sleep is an inhibition that involves the cerebral cortex and other parts of the brain. During sleep, metabolism, hearing, smell, and the intensity of activity of a number of organ systems decrease, muscle tone decreases, and thinking turns off. Sleep is a protective device against overwork of the nervous system. Infants sleep 20-22 hours, schoolchildren - 9-11 hours, adults - 7-8 hours. With lack of sleep, a person loses his ability to work. In order for the body to receive the most complete rest during sleep, it is necessary to go to bed at the same time, eliminate bright light, noise, ventilate the room, etc.

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

Reflexes unconditioned and conditioned.

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

These include:

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

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

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

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

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