Conditioned reflex is an acquired reflex characteristic of an individual (individual). Individuals arise during life and are not genetically fixed (not inherited). They arise under certain conditions and disappear in their absence. They are formed on the basis of unconditioned reflexes with the participation of the higher parts of the brain. Conditioned reflex reactions depend on past experience, on the specific conditions in which the conditioned reflex is formed.
The study of conditioned reflexes is associated primarily with the name of I.P. Pavlov and the students of his school. They showed that a new conditioned stimulus can trigger a reflex response if it is presented for some time together with an unconditioned stimulus. For example, if a dog is given a sniff of meat, then it secretes gastric juice (this is an unconditioned reflex). If the bell rings at the same time as the appearance of meat, then the dog's nervous system associates this sound with food, and gastric juice will be secreted in response to the call, even if meat is not presented. This phenomenon was discovered independently by Edwin Twitmeier at about the same time as in the laboratory of I.P. Pavlov. Conditioned reflexes underlie acquired behavior... These are the simplest programs. The world around us is constantly changing, so only those who quickly and expediently respond to these changes can live in it. With the acquisition of life experience in the cerebral cortex, a system of conditioned reflex connections develops. This system is called dynamic stereotype... It is at the heart of many habits and skills. For example, having learned to skate or bike, we no longer think about how to move so as not to fall.
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Human Anatomy: Conditioned Reflexes
Conditioned reflexes
Higher nervous activity
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Conditioned reflex formation
This requires:
- The presence of 2 stimuli: an unconditioned stimulus and an indifferent (neutral) stimulus, which then becomes a conditioned signal;
- A certain strength of stimuli. The unconditioned stimulus must be strong enough to cause dominant excitation in the central nervous system. An indifferent stimulus should be habitual, so as not to cause a pronounced orienting reflex.
- Repeated combination of stimuli in time, and the first should be affected by an indifferent stimulus, then an unconditioned stimulus. In the future, the action of 2 stimuli continues and ends simultaneously. A conditioned reflex will arise if an indifferent stimulus becomes a conditioned stimulus, that is, it signals the action of an unconditioned stimulus.
- Constancy of the environment - the development of a conditioned reflex requires the constancy of the properties of the conditioned signal.
The mechanism of formation of conditioned reflexes
When the action of an indifferent stimulus excitation arises in the corresponding receptors, and impulses from them enter the cerebral section of the analyzer. When exposed to an unconditioned stimulus, specific excitation of the corresponding receptors occurs, and impulses through the subcortical centers go to the cerebral cortex (the cortical representation of the center of the unconditioned reflex, which is the dominant focus). Thus, in the cerebral cortex, two foci of excitation appear simultaneously: In the cerebral cortex, between the two foci of excitation, according to the dominant principle, a temporary reflex connection is formed. When a temporary connection occurs, the isolated action of a conditioned stimulus causes an unconditioned reaction. In accordance with Pavlov's theory, the consolidation of a temporary reflex connection occurs at the level of the cerebral cortex, and it is based on the principle of dominant.
Types of conditioned reflexes
There are many classifications of conditioned reflexes:
- If the classification is based on unconditioned reflexes, then food, protective, orienting, etc. are distinguished.
- If the classification is based on receptors on which stimuli act, there are exteroceptive, interoceptive and proprioceptive conditioned reflexes.
- Depending on the structure of the applied conditioned stimulus, simple and complex (complex) conditioned reflexes are distinguished.
In real conditions of organism functioning, as a rule, conditioned signals are not separate, single stimuli, but their temporal and spatial complexes. And then a complex of environmental signals acts as a conditioned stimulus. - Distinguish between conditioned reflexes of the first, second, third, etc. order. When a conditioned stimulus is reinforced by an unconditioned one, a first-order conditioned reflex is formed. A conditioned reflex of the second order is formed if the conditioned stimulus is reinforced by a conditioned stimulus to which the conditioned reflex was previously developed.
- Natural reflexes are formed to stimuli, which are natural, accompanying properties of the unconditioned stimulus, on the basis of which they are developed. Natural conditioned reflexes, in comparison with artificial ones, are distinguished by greater ease of formation and greater strength.
Notes
the school of Ivan Petrovich Pavlov conducted vivisector experiments not only on dogs, but also on people. Homeless children aged 6–15 years were used as laboratory material. These were tough experiments, but they made it possible to understand the nature of human thinking. These experiments were carried out in the children's clinic of the 1st LMI, in the Filatovskaya hospital, in the hospital. Rauchfus, in the department of experimental pediatrics of the IEM, as well as in several orphanages. are essential information. In two works of N. I. Krasnogorskiy "Development of the doctrine of the physiological activity of the brain in children" (L., 1939) and "Higher nervous activity of a child" (L., 1958), Professor Mayorov, who was the official chronicler of the Pavlovsk school, melancholy noted: " Some of our collaborators expanded the range of experimental objects and began studying conditioned reflexes in other animal species; in fish, ascidians, birds, lower monkeys, as well as children "(F.P. Mayorov," History of the doctrine of conditioned reflexes ". Moscow, 1954)." laboratory material "of a group of Pavlov's students (prof. N. I. Krasnogorsky , A. G. Ivanov-Smolensky, I. Balakirev, M. M. Koltsova, I. Kanaeva) became street children. Cheka provided a complete understanding in all instances. A. Yushchenko in his work "Conditioned reflexes of a child" (1928 All this is confirmed by protocols, photographs and a documentary film "Mechanics of the Brain" (another name - "Behavior of Animals and Man"; directed by V. Pudovkin, opera by A. Golovnya, production film factory "Mezhrabprom-Rus", 1926)
Higher nervous activity (VND)
Higher nervous activity (HNR) is a complex and interconnected set of nervous processes that underlie human behavior. VND ensures maximum human adaptability to environmental conditions.
At the heart of GNI are complex electrical and chemical processes in the cells of the cerebral cortex. Receiving information through the senses, the brain ensures the interaction of the body with the environment and maintains the constancy of the internal environment in the body.
The doctrine of higher nervous activity is based on the works of I.M. Sechenov - "Reflexes of the brain", I.P. Pavlova (theory of conditioned and unconditioned reflexes), P.K. Anokhin (theory of functional systems) and numerous other works.
Features of human higher nervous activity:
- developed mental activity;
- speech;
- ability to abstract logical thinking.
The beginning of the creation of the doctrine of higher nervous activity was laid by the works of the great Russian scientists I.M. Sechenov and I.P. Pavlova.
Ivan Mikhailovich Sechenov, in his book "Reflexes of the Brain", proved that a reflex is a universal form of interaction between the body and the environment, that is, not only involuntary, but also voluntary, conscious movements have a reflex character. They begin with irritation of any sense organs and continue in the brain in the form of certain neural phenomena that trigger behavioral reactions.
A reflex is the body's response to irritation, which occurs with the participation of the nervous system.
THEM. Sechenov argued that brain reflexes include three links:
- The first, initial link is arousal in the sense organs caused by external influences.
- The second, central link is the processes of excitation and inhibition in the brain. On their basis, mental phenomena arise (sensations, ideas, feelings, etc.).
- The third, final link is a person's movements and actions, that is, his behavior. All these links are interconnected and condition each other.
Sechenov concluded that the brain is an area of \u200b\u200bcontinuous change in excitation and inhibition. These two processes constantly interact with each other, which leads to both strengthening and weakening (delay) of reflexes. He also drew attention to the existence of innate reflexes that people get from their ancestors, and acquired ones that arise during life, as a result of learning. The assumptions and conclusions of I.M.Sechenov were ahead of their time.
The successor of the ideas of I.M. Sechenov became I.P. Pavlov.
All reflexes arising in the body, Ivan Petrovich Pavlov subdivided into unconditioned and conditioned.
Unconditioned reflexes
Unconditioned reflexes are inherited by offspring from parents, persist throughout the life of the organism and are reproduced from generation to generation ( constant). They are characteristic of all individuals of a certain species, i.e. group.
Have unconditioned reflexes persistent reflex arcsthat pass through the brain stem or through the spinal cord (for their implementation participation of the cortex is optionalcerebral hemispheres).
Distinguish between food, defensive, sexual and orienting unconditioned reflexes.
- Food: separation of digestive juices in response to irritation of the oral cavity receptors, swallowing, sucking movements in a newborn.
- Defensive: pulling away a hand that has touched a hot object or with painful irritation, coughing, sneezing, blinking, etc.
- Sexual: Reproduction is associated with sexual reflexes.
- Indicative (I.P. Pavlov called it a reflex "what is it?") provides the perception of an unfamiliar stimulus. An orienting reflex appears in response to a new stimulus: a person is alert, listens, turns his head, squints his eyes, thinks.
Thanks to unconditioned reflexes, the integrity of the organism is preserved, the constancy of its internal environment is maintained and reproduction occurs.
A complex chain of unconditioned reflexes is called instinct.
Example:
A mother nurses and protects her child, birds build nests - these are examples of instincts.
Conditioned reflexes
Along with hereditary (unconditioned), there are reflexes that are acquired by each person during life. Such reflexes individual, and certain conditions are necessary for their formation, therefore they were named conditional.
Conditioned reflexes are complex adaptive reactions of the body, carried out by the higher parts of the central nervous system by forming a temporary connection between the signal stimulus and the unconditional reflex act that reinforces this stimulus. On the basis of the analysis of the patterns of the formation of conditioned reflexes, the school created the doctrine of higher nervous activity (see). Unlike unconditioned reflexes (see), which ensure the adaptation of the body to constant influences of the external environment, conditioned reflexes enable the body to adapt to changing environmental conditions. Conditioned reflexes are formed on the basis of unconditioned reflexes, which requires the coincidence in time of some stimulus from the external environment (conditioned stimulus) with the implementation of one or another unconditioned reflex. The conditioned stimulus becomes a signal of a dangerous or favorable situation, which makes it possible for the body to respond with an adaptive reaction.
Conditioned reflexes are unstable and are acquired in the process of individual development of the organism. Conditioned reflexes are divided into natural and artificial. The former arise in response to natural stimuli in natural conditions of existence: a puppy who has received meat for the first time sniffs it for a long time and timidly eats it, and this act of eating is accompanied. In the future, only the sight and smell of meat causes the puppy to lick and discharge. Artificial conditioned reflexes are developed in an experimental setting, when the conditioned stimulus for the animal is an effect that has nothing to do with unconditioned reactions in the natural conditions of animals' habitation (for example, the flickering of light, the beat of a metronome, sound clicks).
Conditioned reflexes are divided into food, defensive, sexual, orienting, depending on the unconditioned response reinforcing the conditioned stimulus. Conditioned reflexes can be named depending on the recorded response of the body: motor, secretory, autonomic, excretory, and can also be designated by the type of conditioned stimulus - light, sound, etc.
For the development of conditioned reflexes in an experiment, a number of conditions are necessary: \u200b\u200b1) the conditioned stimulus in time must always precede the unconditioned stimulus; 2) the conditioned stimulus should not be strong, so as not to cause its own reaction of the organism; 3) the stimulus usually found in the surrounding conditions of the given animal or person is taken as a conditional one; 4) the animal or person must be healthy, vigorous and have sufficient motivation (see).
There are also conditioned reflexes of various orders. When a conditioned stimulus is reinforced by an unconditioned one, a conditioned reflex of the first order is developed. If some stimulus is reinforced by a conditioned stimulus, to which a conditioned reflex has already been developed, then a conditioned reflex of the second order is developed to the first stimulus. Conditioned reflexes of higher orders are developed with difficulty, which depends on the level of organization of a living organism.
In a dog, conditioned reflexes can be developed up to 5-6 orders, in a monkey - up to 10-12 orders, in humans - up to 50-100 orders.
The works of I.P. Pavlov and his students established that in the mechanism of the onset of conditioned reflexes, the leading role belongs to the formation of a functional connection between the centers of excitation from conditioned and unconditioned stimuli. An important role in this was assigned to the cerebral cortex, where conditioned and unconditioned stimuli, creating centers of excitation, began to interact with each other, creating temporary connections. Subsequently, electrophysiological research methods have established that the interaction between conditioned and unconditioned excitations can first occur at the level of the subcortical structures of the brain, and at the level of the cerebral cortex, the formation of integral conditioned reflex activity is carried out.
However, the cerebral cortex always controls the activity of the subcortical formations.
Studies of the activity of single neurons of the central nervous system using the microelectrode method have established that both conditioned and unconditioned excitations (sensory-biological convergence) come to one neuron. It is especially pronounced on the neurons of the cerebral cortex. These data forced us to abandon the idea of \u200b\u200bthe presence in the cerebral cortex of foci of conditioned and unconditioned excitation and to create a theory of convergent closure of the conditioned reflex. According to this theory, a temporary connection between conditioned and unconditioned arousal arises in the form of a chain of biochemical reactions in the protoplasm of the nerve cell of the cerebral hemispheres.
Modern concepts of conditioned reflexes have significantly expanded and deepened due to the study of the higher nervous activity of animals in the conditions of their free natural behavior. It was found that the environment, along with the time factor, plays an important role in the behavior of the animal. Any stimulus from the external environment can become conditioned, allowing the body to adapt to the surrounding conditions. As a result of the formation of conditioned reflexes, the body reacts some time before the effect of unconditioned stimulation. Consequently, conditioned reflexes contribute to the successful finding of food for animals, helps to avoid danger in advance and to orient themselves most perfectly in the changing conditions of existence.
Reflex - the response of the body is not 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 Are innate reflexes that are inherited by offspring from parents and persist throughout a person's life. Arcs of unconditioned reflexes pass through the spinal cord or brainstem. The cerebral cortex is not involved in their formation. Unconditioned reflexes provide only for those changes in the environment that have often been encountered by many generations of this species.
These include:
Food (salivation, sucking, swallowing);
Defensive (coughing, sneezing, blinking, pulling the hand away from a hot object);
Indicative (mowing eyes, turns);
Sexual (reflexes associated with reproduction and caring for offspring).
The meaning of unconditioned reflexes is that, thanks to them, the integrity of the organism is preserved, the maintenance of 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. An irritant of the sucking reflex - touching the baby's lips with any object (mother's breast, nipple, 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.
Are especially pronounced unconditioned reflexes in various animals. Not only individual reflexes can be inborn, but also more complex forms of behavior, which are called instincts.
Conditioned reflexes- these are reflexes that are easily acquired by the body during life and are formed on the basis of an unconditioned reflex under the action of a conditioned stimulus (light, knock, time, etc.). IP Pavlov studied the formation of conditioned reflexes in dogs and developed a method for obtaining them. To develop a conditioned reflex, an irritant is needed - a signal that triggers the conditioned reflex, repeated repetition of the action of the stimulus allows you to develop a conditioned reflex. When conditioned reflexes are formed, a temporary connection arises between the centers and centers of the unconditioned reflex. Now this unconditioned reflex is not carried out under the influence of completely new external signals. These annoyances from the outside world, to which we were indifferent, can now take on vital importance. During life, many conditioned reflexes are developed, which form the basis of our life experience. But this life agaric makes sense only for this individual and is not inherited by its descendants.
Into an independent category conditioned reflexes allocate conditioned motor reflexes developed during our life, that is, skills or automated actions. The meaning of these conditioned reflexes is the development of new motor skills, the development of new forms of movements. During his life, a person masters many special motor skills associated with his profession. Skills are the foundation of our behavior. Consciousness, thinking, attention are freed from performing those operations that were automated and became the skills of everyday life. The most successful way of mastering skills is systematic exercises, correcting mistakes noticed in time, knowing the ultimate goal of each exercise.
If the conditioned stimulus is not reinforced with an unconditioned one for some time, then the conditioned stimulus is inhibited. But it does not disappear at all. When the experiment is repeated, the reflex is restored very quickly. Inhibition is also observed when exposed to another stimulus of greater strength.
The main form of activity of the nervous system is reflex... All reflexes are usually divided into unconditioned and conditioned.
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Unconditioned reflexes |
Conditioned reflexes |
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1. Congenital genetically programmed reactions of the organism, characteristic of all animals and humans. 2. Reflex arcs of these reflexes are formed in the process prenatal development, sometimes - and in postnatal period. Ex: congenital sexual reflexes are finally formed in a person only by the time of puberty in adolescence. They have little-changing reflex arcs passing through the subcortical parts of the central nervous system. The participation of the cortex in the course of many unconditioned reflexes is optional. 3. Are species-specific, i.e. formed in the process of evolution and are characteristic of all representatives of this species. 4. Relatively constant and persist throughout the life of the organism. 5. Occur on specific (adequate) stimulus for each reflex. 6. Reflex centers are at the level spinal cord and in brain stem |
1. Acquired reactions of higher animals and humans, developed as a result of learning (experience). 2. Reflex arcs are formed in the process postnatal development. They are characterized by high mobility, the ability to change under the influence of environmental factors. Reflex arcs of conditioned reflexes pass through the higher part of the brain - the cerebral cortex. 3. Are individual, i.e. arise from life experience. 4. Fickle and depending on certain conditions, they can be developed, fixed or fade away. 5. May form on any body-perceived irritant 6. Reflex centers are located in cerebral cortex |
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Example: food, sexual, defensive, indicative. |
Example: salivation to the smell of food, precise movements when writing, playing musical instruments. |
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Value:help survival, this is "the application of the experience of ancestors in practice" |
Value: help to adapt to changing environmental conditions. |
Classification of unconditioned reflexes.
The question of classifying unconditioned reflexes is still open, although the main types of these reactions are well known.
1. Food reflexes... For example, salivation when food enters the mouth or the sucking reflex in a newborn baby.
2. Defensive reflexes... Protect the body from various adverse effects. For example, the reflex of twitching the hand when the finger is painful.
3. Orientation reflexes, or reflexes "What is?", as IP Pavlov called them. A new and unexpected stimulus attracts attention, for example, turning the head in the direction of an unexpected sound. A similar reaction to novelty, which has an important adaptive value, is observed in various animals. It is expressed in alertness and listening, sniffing and examining new objects.
4. Play reflexes... For example, children's games in a family, hospital, etc., during which children create models of possible life situations and carry out a kind of "preparation" for various life surprises. The unconditionally reflex play activity of 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. Parentreflexes are associated with the birth and feeding of offspring.
7. Reflexes that ensure movement and balance of the body in space.
8. Reflexes supporting constancy of the internal environment of the body.
Complex unconditioned reflexes I.P. Pavlov called instincts, the biological nature of which remains unclear in its details. In a simplified form, instincts can be represented as a complex interconnected series of simple innate reflexes.
Physiological mechanisms of the formation of conditioned reflexes
To understand the nervous mechanisms of conditioned reflexes, let us consider such a simple conditioned reflex reaction as an increase in salivation in a person at the sight of a lemon. it natural conditioned reflex. In a person who has never tasted lemon, this object does not cause any reactions, except curiosity (orienting reflex). What is the physiological connection between such functionally distant organs as the eyes and the salivary glands? The solution to this issue was addressed by I.P. Pavlov.
The connection between the nerve centers that regulate the processes of salivation and analyze visual stimuli arises as follows:
Excitation that occurs in the visual receptors at the sight of a lemon travels through centripetal fibers to the visual cortex (occipital region) and causes excitement cortical neurons - arises focus of excitement.
2. If after this a person gets the opportunity to taste lemon, then a focus of arousal 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 (lemon taste) is stronger than the conditioned stimulus (external signs of lemon), the food focus of excitation has a dominant (main) meaning and "attracts" excitation from the visual center.
4. Between two previously unconnected nerve centers arises nervous temporal connection, i.e. a kind of temporary "pontoon bridge" connecting two "shores".
5. Now the excitement arising in the visual center quickly "passes" along the "bridge" of the temporary connection to the food center, and from there along the efferent nerve fibers to the salivary glands, causing salivation.
Thus, the formation of a conditioned reflex requires the following conditions:
1. The presence of a conditioned stimulus and unconditioned reinforcement.
2. The conditioned stimulus should always somewhat precede the unconditioned reinforcement.
3. The conditioned stimulus by the strength of its effect should be weaker than the unconditioned stimulus (reinforcement).
4. Repetition.
5. It is necessary to have a normal (active) functional state of the nervous system, 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 when a conditioned signal is combined with unconditioned reinforcement are called reflexes of the first order... If a reflex is developed, then it can also become the basis of a new conditioned reflex. It is called second order reflex... Reflexes worked out on them - third order reflexes etc. In humans, they are formed on verbal signals, supported by the results of joint activities of people.
Any change in the environment and internal environment of the organism can be a conditioned stimulus; bell, electric light, tactile irritation of the skin, etc. As unconditioned stimuli (reinforcement) use food reinforcement and pain irritation.
The development of conditioned reflexes with such unconditioned reinforcement is the fastest. In other words, reward and punishment are powerful factors contributing to the formation of conditioned reflex activity.
Classification of conditioned reflexes
In view of their large number it is difficult.
By the location of the receptor:
1. exteroceptive - conditioned reflexes formed during stimulation of exteroceptors;
2. interoceptive - reflexes formed upon 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 when natural unconditioned stimuli act on the receptors;
2. artificial - under the action of indifferent stimuli. For example, a child's salivation at the sight of his favorite sweets is a natural conditioned reflex (salivation when the oral cavity is irritated by any food is an unconditioned reflex), and the salivation that occurs in a hungry child at the sight of dinner dishes is an artificial reflex.
By the sign of action:
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 brake.
By the nature of the response:
1. motor;
2. vegetative are formed from internal organs - heart, lungs, etc. Impulses from them, penetrating into the cerebral cortex, are immediately inhibited, without reaching our consciousness, because of this we do not feel their location in the state of health. And in case of illness, we know exactly where the diseased organ is located.
Reflexes take a special place for a while,the formation of which is associated with regularly repeating irritants at the same time, for example, with food intake. That is why by the time of eating, the functional activity of the digestive organs increases, which has a biological meaning. Reflexes for a while belong to the group of so-called trace conditioned reflexes. These reflexes are developed if unconditioned reinforcement is given 10 to 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 imitations, which, according to L.A. Orbeli are also a kind of conditioned reflexes. To develop them, it is enough to be a "spectator" of the experiment. For example, if you develop a conditioned reflex in one person in full view of another, then the “viewer” also has the formation of appropriate temporary connections. In children, imitative reflexes play an important role in the formation of motor skills, speech and social behavior, in adults, in the acquisition of labor skills.
There are extrapolation reflexes - the ability of humans and animals to foresee situations favorable or unfavorable for life.