Unconditioned and early conditioned reflexes. Unconditioned reflexes

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

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

Comparison of conditioned and unconditioned reflexes

Development of a conditioned reflex

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

Inhibition of conditioned reflexes

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

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

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

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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

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




5) are congenital
6) are not inherited

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Choose three correct answers out of six and write down the numbers under which they are indicated. Unconditioned reflexes, ensuring life activity human body,
1) are produced in the process 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

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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

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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

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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

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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

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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

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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

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

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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

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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

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

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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

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

Answer

© D.V. Pozdnyakov, 2009-2019

Reflexes- this is the body’s response to irritation of sensitive nerve formations - receptors, carried out with the participation nervous system.

Types of reflexes: conditioned and unconditioned

Reflex arc

With the help of a reflex, excitation spreads along reflex arcs and the process of inhibition occurs.

Reflex arc- this is the path along which nerve impulses are carried out during a reflex.

Reflex arc diagram

5 reflex arc links:

1. Receptor - perceives irritation and converts it into a nerve impulse.

2. Sensitive (centripetal) neuron - transmits excitation to the center.

3. Nerve center - excitation switches from sensory neurons to motor ones (there is an interneuron in the three-neuron arch).

4. Motor (centrifugal) neuron - carries excitation from the central nervous system to the working organ.

5. Working body - reacts to the received irritation.

Information from the receptors of the working organ enters the nerve center to confirm the effectiveness of the reaction and, if necessary, coordinate it.

Diagram of a knee reflex reflex arc (a simple arc of two neurons)

Diagram of the reflex arc of the flexion reflex (complex arc of several neurons)

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A source of information:

Biology in tables and diagrams./ Edition 2, - St. Petersburg: 2004.

Rezanova E.A. Human biology. In tables and diagrams./ M.: 2008.

The outstanding Russian physiologist I.M. Sechenov was the first to express the idea of ​​the connection between human consciousness and thinking and reflex activity 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 nervous 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 about the higher nervous activity of man have been convincingly proven to be untenable and unscientific religious ideas about "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. Her overwork leads to vital distress important functions 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 vacation this involves 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.

Alternation of physical and mental labor, rationalization of work, adherence to the daily routine, leisure are of paramount importance for protecting the central nervous system from fatigue.

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- This innate reflexes, which are inherited by offspring from their parents and persist throughout a person’s life. The arcs of unconditioned reflexes pass through 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 irritations from the surrounding world, to which we were indifferent, can now become vitally important. Throughout life, many conditioned reflexes are developed that form the basis of our life experience. But this vital experience has meaning only for a given individual and is not inherited by its descendants.

In a separate category conditioned reflexes 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, attention are freed from performing those operations that have become automated and become skills 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.

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, that is, characteristic of all representatives of a given 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 that have developed cortex cerebral hemispheres, 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 lower departments central nervous system - subcortical nuclei, brain stem and spinal cord. It should be noted, however, that in humans and monkeys, who have high degree corticalization of functions, many complex unconditioned reflexes are carried out with the obligatory participation of the cerebral cortex. This is proven by the fact that its lesions in primates lead to pathological disorders of unconditioned reflexes and the disappearance of some of them.

It should also be emphasized that not all unconditioned reflexes appear immediately at the time of birth. Many unconditioned reflexes, for example, those associated with locomotion and sexual intercourse, arise in humans and animals 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 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 signals from the external world that are initially indifferent become stimuli. certain type activities.

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