A reflex is the body's response to internal or external stimulation, carried out and controlled by the central nervous system. The first scientists who developed ideas about human behavior, which had previously been a mystery, were our compatriots I.P. Pavlov and I.M. Sechenov.

What are unconditioned reflexes?

An unconditioned reflex is an innate, stereotypical reaction of the body to the influence of the internal or environmental environment, inherited by the offspring from the parents. It remains in a person throughout his life. Reflex arcs pass through the brain and spinal cord; the cerebral cortex does not take part in their formation. The significance of the unconditioned reflex is that it ensures the adaptation of the human body directly to those environmental changes that often accompanied many generations of his ancestors.

What reflexes are unconditioned?

The unconditioned reflex is the main form of activity of the nervous system...

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A reflex is a stereotypical (monotonous, repeated in the same way) response of the body to the action of stimuli with the obligatory participation of the central nervous system.

Reflexes are divided into unconditioned and conditioned.

Unconditioned reflexes include:

1. Reflexes aimed at preserving the species. They are the most biologically significant, prevail over other reflexes, are dominant in a competitive situation, namely: sexual reflex, parental reflex, territorial reflex (this is the protection of one’s territory; this reflex manifests itself in both animals and humans), hierarchical reflex (the principle of subordination is reflexively embedded in a person, i.e. we are ready to obey, but we definitely want to command too - relationships in society are built on this, but there is also a biological basis).

2. Self-preservation reflexes. They are aimed at preserving the individual, personality, individual: drinking reflex, eating reflex, defensive reflex, aggressiveness reflex (attack is the best...

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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.
Unconditional...

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Unconditioned reflexes are constant innate reactions of the body to certain influences from the external world, carried out through the nervous system and not requiring special conditions for their occurrence.

All unconditioned reflexes, according to the degree of complexity and severity of the body’s reactions, are divided into simple and complex; depending on the type of reaction - to food, sexual, defensive, orientation-exploratory, etc.; depending on the animal’s attitude to the stimulus - into biologically positive and biologically negative. Unconditioned reflexes arise mainly under the influence of contact irritation: food unconditioned reflex - when food enters the mouth and acts on the receptors of the tongue; defensive - when pain receptors are irritated. However, the emergence of unconditioned reflexes is also possible under the influence of such stimuli as the sound, sight and smell of an object. Thus, the sexual unconditioned reflex occurs under the influence of a specific sexual stimulus (species...

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Physiology of higher nervous activity. Congenital forms of behavior. Unconditioned reflexes.

Unconditioned reflexes are the body’s innate responses to stimulation. Properties of unconditioned reflexes:

1. They are congenital, i.e. are inherited

2. Inherited by all representatives of a given animal species

3. For the occurrence of an unconditioned reflex reaction, the action of a specific stimulus is necessary (mechanical irritation of the lips, sucking reflex in a newborn)

4. They have a permanent receptive field (area of ​​perception of a specific stimulus).

5. They have a constant reflex arc.

I.P. Pavlov divided all unconditioned reflexes (B.U.R.) into simple (sucking), complex (sweating) and complex (food, defensive, sexual, etc.). Currently, all unconditioned reflexes, depending on their meaning, are divided into 3 groups:

1. Vital (vital). They ensure the preservation of the individual. To them...

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Each person, as well as all living organisms, has a number of vital needs: food, water, comfortable conditions. Everyone has instincts of self-preservation and continuation of their kind. All mechanisms aimed at satisfying these needs are laid down at the genetic level and appear simultaneously with the birth of the organism. These are innate reflexes that help to survive.

The concept of an unconditioned reflex

The word reflex itself is not something new and unfamiliar for each of us. Everyone has heard it in their life, and quite many times. This term was introduced into biology by I.P. Pavlov, who devoted a lot of time to studying the nervous system.

According to the scientist, unconditioned reflexes arise under the influence of irritating factors on the receptors (for example, withdrawing a hand from a hot object). They contribute to the body’s adaptation to those conditions that remain practically unchanged.

This is the so-called product of historical...

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To pull your hand away from a hot kettle, to close your eyes when there is a flash of light... We perform such actions automatically, without having time to think about what exactly we are doing and why. These are unconditioned human reflexes - innate reactions characteristic of all people without exception.

Discovery history, types, differences

Before examining unconditioned reflexes in detail, we will have to take a short excursion into biology and talk about reflex processes in general.

So what is a reflex? In psychology, this is the name given to the body’s response to changes in the external or internal environment, which is carried out using the central nervous system. Thanks to this ability, the body quickly adapts to changes in the surrounding world or in its internal state. For its implementation, a reflex arc is necessary, that is, the path along which the signal of irritation passes from the receptor to the corresponding organ.

Reflex reactions were first described by Rene Descartes in the 17th century...

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Features of unconditioned reflexes

In the specialized literature, in conversations between specialist dog handlers and amateur trainers, the term “reflex” is often used, but there is no common understanding of the meaning of this term among dog handlers. Now many people are interested in Western training systems, new terms are being introduced, but few people fully understand the old terminology. We will try to help systematize ideas about reflexes for those who have already forgotten a lot, and to gain these ideas for those who are just beginning to master the theory and methods of training.

A reflex is the body's response to a stimulus.

(If you have not read the article on irritants, be sure to read that first and then move on to this material). Unconditioned reflexes are divided into simple (food, defensive, sexual, visceral, tendon) and complex reflexes (instincts, emotions). Some researchers...

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Types of conditioned reflexes

Depending on the characteristics of the responses, the nature of the stimuli, the conditions of their use and reinforcement, etc., various types of conditioned reflexes are distinguished. These types are classified based on various criteria in accordance with the objectives. Some of these classifications are of great importance both theoretically and practically, including in sports activities.

Natural (natural) and artificial conditioned reflexes. Conditioned reflexes formed in response to signals that characterize the constant properties of unconditioned stimuli (for example, the smell or type of food) are called natural conditioned reflexes.

An illustration of the laws governing the formation of natural conditioned reflexes are the experiments of I. S. Tsitovich. In these experiments, puppies of the same litter were kept on different diets: some were fed only meat, others only milk. Animals fed meat have the appearance and smell of it...

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Reflex (from Latin reflexus - reflected) is a stereotypical reaction of a living organism to a certain influence, taking place with the participation of the nervous system. According to the generally accepted classification, reflexes are divided into unconditioned and conditioned.

Unconditioned reflexes are innate, characteristic of a given species, responses to environmental influences.

1. Vital (life). The instincts of this group ensure the preservation of the life of the individual. They are characterized by the following signs:

a) failure to satisfy the corresponding need leads to the death of the individual; And

b) no other individual of a given species is needed to satisfy a particular need.

Vital instincts include:

Food,

Drinking,

Defensive,

Sleep-wake regulation,

Saving reflex...

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Classification of unconditioned reflexes

I.P. Pavlov at one time divided unconditioned reflexes into three groups: simple, complex and complex unconditioned reflexes. Among the most complex unconditioned reflexes, he identified the following: 1) individual - food, active and passive defensive, aggressive, freedom reflex, exploratory, play reflex; 2) species - sexual and parental. According to Pavlov, the first of these reflexes ensure the individual self-preservation of the individual, the second - the preservation of the species.

P.V. Simonov identified 3 classes of reflexes:

1. Vital unconditioned reflexes ensure individual and species preservation

body. These include food, drinking, sleep regulation, defensive and orientation reflex (biological caution reflex), energy saving reflex and many others. The criteria for the reflexes of the vital group are the following: 1) failure to satisfy the corresponding need leads to the physical death of the individual and 2) implementation...

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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...

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Unconditioned reflexes - what are they and what is their role?

Such habitual actions as breathing, swallowing, sneezing, blinking occur without conscious control, are innate mechanisms, help a person or animal to survive and ensure the preservation of the species - all these are unconditioned reflexes.

What is an unconditioned reflex?

I.P. Pavlov, a scientist-physiologist, devoted his life to the study of higher nervous activity. In order to understand what human unconditioned reflexes are, it is important to consider the meaning of the reflex as a whole. Any organism that has a nervous system carries out reflex activity. Reflex is a complex reaction of the body to internal and external stimuli, carried out in the form of a reflex response.

Unconditioned reflexes are innate stereotypical reactions laid down at the genetic level in response to changes in internal homeostasis or environmental conditions. For the emergence of unconditioned reflexes, special conditions are...

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A reflex is the body's response to internal or external stimulation, carried out and controlled by the central nervous system. The first scientists who developed ideas about what was previously a mystery were our compatriots I.P. Pavlov and I.M. Sechenov.

What are unconditioned reflexes?

An unconditioned reflex is an innate, stereotypical reaction of the body to the influence of the internal or environmental environment, inherited by the offspring from the parents. It remains in a person throughout his life. Reflex arcs pass through the brain and the cerebral cortex does not take part in their formation. The significance of the unconditioned reflex is that it ensures the adaptation of the human body directly to those environmental changes that often accompanied many generations of his ancestors.

What reflexes are unconditioned?

An unconditioned reflex is the main form of activity of the nervous system, an automatic reaction to a stimulus. And since a person is influenced by various factors, the reflexes are different: food, defensive, orientation, sexual... Food include salivation, swallowing and sucking. Defensive actions include coughing, blinking, sneezing, and jerking limbs away from hot objects. Approximate reactions include turning the head and squinting the eyes. Sexual instincts include those associated with reproduction, as well as caring for offspring. The significance of the unconditioned reflex is that it ensures the preservation of the integrity of the body and maintains the constancy of the internal environment. Thanks to him, reproduction occurs. Even in newborn children, one can observe an elementary unconditioned reflex - this is sucking. By the way, it is the most important. The irritant in this case is touching the lips of any object (pacifier, mother's breast, toy or finger). Another important unconditioned reflex is blinking, which occurs when a foreign body approaches the eye or touches the cornea. This reaction belongs to the protective or defensive group. Also observed in children, for example, when exposed to strong light. However, the signs of unconditioned reflexes are most clearly manifested in various animals.

What are conditioned reflexes?

Conditioned reflexes are those acquired by the body during life. They are formed on the basis of inherited ones, subject to exposure to an external stimulus (time, knocking, light, and so on). A striking example is the experiments conducted on dogs by academician I.P. Pavlov. He studied the formation of this type of reflexes in animals and was the developer of a unique method for obtaining them. So, to develop such reactions, the presence of a regular stimulus - a signal - is necessary. It triggers the mechanism, and repeated repetition of the stimulus allows it to develop. In this case, a so-called temporary connection arises between the arcs of the unconditioned reflex and the centers of the analyzers. Now the basic instinct awakens under the influence of fundamentally new external signals. These stimuli from the surrounding world, to which the body was previously indifferent, begin to acquire exceptional, vital importance. Each living creature can develop many different conditioned reflexes during its life, which form the basis of its experience. However, this applies only to this particular individual; this life experience will not be inherited.

An independent category of conditioned reflexes

It is customary to classify into a separate category conditioned reflexes of a motor nature developed throughout life, that is, skills or automated actions. Their meaning is to master new skills, as well as develop new motor forms. For example, over the entire period of his life a person masters many special motor skills that are associated with his profession. They are the basis of our behavior. Thinking, attention, and consciousness are freed up when performing operations that have reached automaticity and become a reality of everyday life. The most successful way to master skills is to systematically perform the exercise, timely correction of noticed errors, and knowledge of the ultimate goal of any task. If the conditioned stimulus is not reinforced by the unconditioned stimulus for some time, it is inhibited. However, it does not disappear completely. If you repeat the action after some time, the reflex will be restored quite quickly. Inhibition can also occur when a stimulus of even greater strength appears.

Compare unconditioned and conditioned reflexes

As mentioned above, these reactions differ in the nature of their occurrence and have different formation mechanisms. In order to understand what the difference is, just compare unconditioned and conditioned reflexes. Thus, the first ones are present in a living creature from birth; throughout life they do not change or disappear. In addition, unconditioned reflexes are the same in all organisms of a particular species. Their significance lies in preparing a living being for constant conditions. The reflex arc of this reaction passes through the brain stem or spinal cord. As an example, here are some (congenital): active secretion of saliva when a lemon enters the mouth; sucking movement of the newborn; coughing, sneezing, withdrawing hands from a hot object. Now let's look at the characteristics of conditioned reactions. They are acquired throughout life, can change or disappear, and, no less important, each organism has its own individual (its own). Their main function is to adapt a living creature to changing conditions. Their temporary connection (reflex centers) is created in the cerebral cortex. An example of a conditioned reflex is the reaction of an animal to a nickname or the reaction of a six-month-old child to a bottle of milk.

Unconditioned reflex diagram

According to the research of academician I.P. Pavlova, the general scheme of unconditioned reflexes is as follows. Certain receptor nerve devices are affected by certain stimuli from the internal or external world of the body. As a result, the resulting irritation transforms the entire process into the so-called phenomenon of nervous excitation. It is transmitted along nerve fibers (as if through wires) to the central nervous system, and from there it goes to a specific working organ, already turning into a specific process at the cellular level of a given part of the body. It turns out that certain stimuli are naturally connected with this or that activity in the same way as cause and effect.

Features of unconditioned reflexes

The characteristics of unconditioned reflexes presented below systematize the material presented above; it will help to finally understand the phenomenon we are considering. So, what are the features of inherited reactions?

Unconditioned instinct and reflex of animals

The exceptional constancy of the nervous connection underlying unconditional instinct is explained by the fact that all animals are born with a nervous system. She is already able to respond appropriately to specific environmental stimuli. For example, a creature may flinch at a sharp sound; he will secrete digestive juice and saliva when food enters his mouth or stomach; it will blink when visually stimulated, and so on. Innate in animals and humans are not only individual unconditioned reflexes, but also much more complex forms of reactions. They are called instincts.

An unconditioned reflex, in fact, is not a completely monotonous, template, transfer reaction of an animal to an external stimulus. It is characterized, although elementary, primitive, but still by variability, variability, depending on external conditions (strength, peculiarities of the situation, position of the stimulus). In addition, it is influenced by the internal states of the animal (decreased or increased activity, posture, etc.). So, also I.M. Sechenov, in his experiments with decapitated (spinal) frogs, showed that when the toes of the hind legs of this amphibian are exposed, the opposite motor reaction occurs. From this we can conclude that the unconditioned reflex still has adaptive variability, but within insignificant limits. As a result, we find that the balancing of the organism and the external environment achieved with the help of these reactions can be relatively perfect only in relation to slightly changing factors of the surrounding world. The unconditioned reflex is not able to ensure the animal’s adaptation to new or sharply changing conditions.

As for instincts, sometimes they are expressed in the form of simple actions. For example, the rider, thanks to his sense of smell, finds the larvae of another insect under the bark. It pierces the bark and lays its egg in the found victim. This ends all of its actions that ensure continuation of the family. There are also complex unconditioned reflexes. Instincts of this kind consist of a chain of actions, the totality of which ensures procreation. Examples include birds, ants, bees and other animals.

Species specificity

Unconditioned reflexes (specific) are present in both humans and animals. It should be understood that such reactions will be the same in all representatives of the same species. An example is a turtle. All species of these amphibians retract their heads and limbs into their shell when danger arises. And all the hedgehogs jump and make a hissing sound. In addition, you should know that not all unconditioned reflexes occur at the same time. These reactions vary with age and season. For example, the breeding season or the motor and sucking actions that appear in an 18-week fetus. Thus, unconditioned reactions are a kind of development for conditioned reflexes in humans and animals. For example, as cubs grow older, they transition into the category of synthetic complexes. They increase the body's adaptability to external environmental conditions.

Unconditional inhibition

In the process of life, each organism is regularly exposed - both from the outside and from the inside - to various stimuli. Each of them is capable of causing a corresponding reaction - a reflex. If all of them could be realized, then the life activity of such an organism would become chaotic. However, this does not happen. On the contrary, reactionary activity is characterized by consistency and orderliness. This is explained by the fact that unconditioned reflexes are inhibited in the body. This means that the most important reflex at a particular moment in time delays the secondary ones. Typically, external inhibition can occur at the moment of starting another activity. The new pathogen, being stronger, leads to the attenuation of the old one. And as a result, the previous activity will automatically stop. For example, a dog is eating, and at that moment the doorbell rings. The animal immediately stops eating and runs to meet the newcomer. There is a sharp change in activity, and the dog’s salivation stops at this moment. Unconditional inhibition of reflexes also includes some innate reactions. In them, certain pathogens cause the complete cessation of certain actions. For example, the anxious clucking of a hen makes the chicks freeze and hug the ground, and the onset of darkness forces the canary to stop singing.

In addition, there is also a protective It arises as a response to a very strong stimulus that requires the body to take actions that exceed its capabilities. The level of such influence is determined by the frequency of impulses of the nervous system. The more excited a neuron is, the higher the frequency of the stream of nerve impulses it generates. However, if this flow exceeds certain limits, then a process will arise that will begin to interfere with the passage of excitation through the neural circuit. The flow of impulses along the reflex arc of the spinal cord and brain is interrupted, resulting in inhibition that preserves the executive organs from complete exhaustion. What conclusion follows from this? Thanks to the inhibition of unconditioned reflexes, the body selects from all possible options the most adequate one, capable of protecting against excessive activity. This process also contributes to the exercise of so-called biological precautions.

The term “reflex” was introduced by the French scientist R. Descartes in the 17th century. But to explain mental activity it was used by the founder of Russian materialistic physiology I.M. Sechenov. Developing the teachings of I.M. Sechenov. I. P. Pavlov experimentally studied the peculiarities of the functioning of reflexes and used the conditioned reflex as a method for studying higher nervous activity.

He divided all reflexes into two groups:

• unconditional;
• conditional.

Unconditioned reflexes

Unconditioned reflexes- innate reactions of the body to vital stimuli (food, danger, etc.).

They do not require any conditions for their production (for example, the release of saliva at the sight of food). Unconditioned reflexes are a natural reserve of ready-made, stereotypical reactions of the body. They arose as a result of the long evolutionary development of this animal species. Unconditioned reflexes are the same in all individuals of the same species. They are carried out using the spinal and lower parts of the brain. Complex complexes of unconditioned reflexes manifest themselves in the form of instincts.

Rice. 14. The location of some functional zones in the human cerebral cortex: 1 - zone of speech production (Broca's center), 2 - area of ​​the motor analyzer, 3 - area of ​​analysis of oral verbal signals (Wernicke's center), 4 - area of ​​the auditory analyzer, 5 - analysis of written verbal signals, 6 - visual analyzer area

Conditioned reflexes

But the behavior of higher animals is characterized not only by innate, i.e., unconditioned reactions, but also by such reactions that are acquired by a given organism in the process of individual life activity, i.e. conditioned reflexes. The biological meaning of the conditioned reflex is that numerous external stimuli that surround the animal in natural conditions and in themselves do not have vital significance, preceding in the animal’s experience food or danger, the satisfaction of other biological needs, begin to act as signals, by which the animal orients its behavior (Fig. 15).

So, the mechanism of hereditary adaptation is an unconditioned reflex, and the mechanism of individual variable adaptation is conditioned a reflex produced when vital phenomena are combined with accompanying signals.

Rice. 15. Scheme of formation of a conditioned reflex

• a - salivation is caused by an unconditioned stimulus - food;
• b - excitement from a food stimulus is associated with a previous indifferent stimulus (light bulb);
• c - the light of the light bulb became a signal of the possible appearance of food: a conditioned reflex was developed to it

A conditioned reflex is developed on the basis of any of the unconditioned reactions. Reflexes to unusual signals that do not occur in a natural environment are called artificial conditioned. In laboratory conditions, it is possible to develop many conditioned reflexes to any artificial stimulus.

I. P. Pavlov associated with the concept of a conditioned reflex principle of signaling of higher nervous activity, the principle of synthesis of external influences and internal states.

Pavlov's discovery of the basic mechanism of higher nervous activity - the conditioned reflex - became one of the revolutionary achievements of natural science, a historical turning point in the understanding of the connection between the physiological and the mental.

Understanding the dynamics of formation and changes in conditioned reflexes began the discovery of complex mechanisms of human brain activity and the identification of patterns of higher nervous activity.

Continuation. See No. 34, 35, 36/2004

Congenital and acquired forms of behavior

Lessons on the topic: “Physiology of higher nervous activity”

Table. Comparison of unconditioned and conditioned reflexes

They are carried out due to the activity of the cerebral cortex, i.e.
reflex arcs pass through the cerebral cortex

Lesson 5. Generalization of knowledge on the topic “Acquired forms of behavior. Conditioned reflex"

Equipment:

tables, diagrams and drawings illustrating acquired forms of behavior, mechanisms for the development of conditioned reflexes.

DURING THE CLASSES

I. Test of knowledge

Working with cards
1. The advantage of behavior formed as a result of learning is that it:
a) is carried out quickly;
b) is carried out the same way every time;
c) provides answers in changing environmental conditions;

d) done correctly the first time;

e) does not occupy a place in the genetic program of the organism.

4. It is known that the strength (biological significance) of the conditioned stimulus should not exceed the strength of the unconditioned stimulus. Otherwise, the conditioned reflex cannot be developed. Therefore, it is very difficult to develop, for example, a conditioned food reflex to painful stimulation (electric current). However, in the laboratory of I.P. In Pavlov’s famous experiments, Erofeeva managed to develop such a conditioned reflex. When exposed to a current (conditioned stimulus), the dog salivated, it licked its lips and wagged its tail. How did you achieve this?

5. During one of the concerts, a listener suddenly began to experience pain in the heart area. Moreover, the onset of pain coincided with the performance of one of Chopin’s nocturnes. Since then, every time the man heard this music, his heart ached. Explain this pattern.

Oral knowledge test on questions

1. Learning and its methods (habituation, trial and error).
2. Imprinting and its characteristics.
3. Methods for developing conditioned reflexes.
4. Mechanisms for the development of conditioned reflexes
5. General properties and classification of conditioned reflexes.
6. Rational activity of animals.
7. Dynamic stereotype and its meaning.

Checking the completion of the table “Comparison of unconditioned and conditioned reflexes”

The children had to fill out the table as homework after the previous lesson.

Biological dictation

The teacher reads out the characteristics of reflexes under numbers, and students, working on the options, write down the numbers of the correct answers: option I – unconditioned reflexes, option II – conditioned reflexes.

1. Passed on by inheritance.
2. Not inherited.
3. Reflex centers are located in the subcortical nuclei, brain stem and spinal cord.
4. Reflex centers are located in the cerebral cortex.
5. There is no species specificity; each individual of the species develops its own reflexes.
6. Species specificity - these reflexes are characteristic of all individuals of a certain species.
7. Stable throughout life.
8. Change (new reflexes arise, and old ones fade away).
9. The reasons for the formation of reflexes are events that are vital for the whole species.
10. The causes of reflexes are signals that arise from personal past experience and warn of an important event.

Answers: Option I – 1, 3, 6, 7, 9;

Option II – 2, 4, 5, 8, 10.
Laboratory work No. 2.

Lesson 5.“Development of conditioned reflexes in humans on the basis of unconditioned reflexes”

rubber bulb for pumping air, metronome.

1. Turn on the metronome at a rhythm of 120 beats per minute and on its second or third beat, press the bulb, directing a stream of air into the subject’s eye.

2. Repeat the steps described in step 1 until the blinking steadily (at least 2-3 times in a row) precedes the pressing of the bulb.

3. After the blink reflex has been developed, turn on the metronome without directing the air stream to the eye. What do you observe?

Draw a conclusion.

What reflex was developed in the subject during the actions you performed?

What performs the role of unconditioned and conditioned stimuli in the developed reflex? What is the difference between the arcs of the unconditioned blink and conditioned blink reflexes?

Homework
Repeat the material about the mechanisms of development of conditioned reflexes in animals and humans.

Lesson 6–7. Congenital and acquired inhibition, their types and characteristics

Equipment:

tables, diagrams and drawings illustrating acquired forms of behavior, mechanisms for the development of conditioned reflexes.

DURING THE CLASSES

Equipment

: tables, diagrams and drawings illustrating the mechanisms of development of conditioned reflexes, various types of congenital and acquired inhibition.

1. Thanks to what innate nervous mechanisms can an animal distinguish good quality food from spoiled food? What role do neurons and their synapses play in these processes?

2. What facts can be used to prove that instinct is a chain of interconnected unconditioned reflexes? How do instincts interact with acquired conditioned reflexes?

3. When an infant sees a bottle of kefir, he smacks his lips; a person salivates when he sees a lemon being cut;

Wanting to know what time it is, a man looks at his hand, where he usually wears his watch, although he forgot it at home.
Explain the described phenomena.
Knowledge test
Choose the correct answers to the given statements.
1. This is an unconditioned stimulus.
2. It is an indifferent stimulus.
3. This is an unconditioned reflex.
4. This is a conditioned reflex.
5. This is a combination of an indifferent stimulus with an unconditioned one.

6. Without these stimuli, the conditioned salivary reflex is not formed.

7. Stimulus that excites the visual cortex.
8. An irritant that excites the gustatory cortex.
9. Under this condition, a temporary connection is formed between the visual and gustatory zones of the cortex.
Answer options
A. Turning on the light bulb before experiments without feeding.

Answers: B. Food in the mouth.

II. Learning new material

1. Excitation and inhibition are the main processes of nervous activity

As you already know, the regulatory function of the central nervous system is carried out through two processes - excitation and inhibition.

Conversation with students on issues

What is arousal?

What is braking?

Why is the process of excitation called the active state of nervous tissue?

What does excitation of motor centers lead to?

Thanks to what process can we mentally imagine them without performing any actions?

What processes enable complex coordinated actions such as walking?

Thus, excitation– this is an active state of nervous tissue in response to the action of various stimuli of sufficient strength. When excited, neurons generate electrical impulses. Braking- This is an active nervous process leading to inhibition of excitation.

2. General characteristics of cortical inhibition

Excitation and inhibition of I.P. Pavlov called them the true creators of nervous activity.

Excitation is involved in the formation of conditioned reflexes and their implementation. The role of inhibition is more complex and varied. It is the process of inhibition that makes conditioned reflexes a mechanism of subtle, precise and perfect adaptation to the environment.

According to I.P. Pavlov, the cortex is characterized by two forms of inhibition: unconditional and conditioned.

Unconditional inhibition does not require development; it is inherent in the body from birth (reflexive holding of breath when there is a strong smell of ammonia, inhibition in the triceps brachii muscle during the action of the biceps brachii, etc.). Conditioned inhibition is developed in the process of individual experience. The following types of braking are distinguished. Unconditional braking: beyond (protective); external; innate reflexes.

Conditional braking:

extinct; differentiation;

Depending on the reasons underlying the inhibition processes, the following types of unconditional inhibition are distinguished.

Transcendental, or protective, braking occurs in response to very strong stimuli that require the body to act beyond its capabilities. The strength of irritation is determined by the frequency of nerve impulses. The more excited a neuron is, the higher the frequency of nerve impulses it generates. But if this flow exceeds known limits, processes arise that prevent the passage of excitation along the chain of neurons. The flow of nerve impulses following the reflex arc is interrupted, and inhibition occurs, which protects the executive organs from exhaustion.

Cause of external braking is outside the structures of the inhibitory reflex, it comes from another reflex. This type of inhibition occurs whenever a new activity is started.

The new excitation, being stronger, causes inhibition of the old one. As a result, the previous activity is automatically terminated.

For example, a dog has developed a strong conditioned reflex to light, and the lecturer wants to demonstrate it to the audience. The experiment fails - there is no reflex. An unfamiliar environment, the noise of a crowded audience are new signals that completely turn off conditioned reflex activity, and new excitation arises in the cortex. If the dog is brought into the audience several times, then new signals, which turn out to be biologically indifferent, fade away, and conditioned reflexes are carried out unhindered. To be continued

Unconditioned reflexes Reflex
Unconditioned reflexes include sucking and motor reflexes, which are already characteristic of an 18-week fetus. Unconditioned reflexes are the basis for the development of conditioned reflexes in animals and humans. In children, with age, they turn into synthetic complexes of reflexes, which increases the body’s adaptability to the external environment.

Conditioned reflexes- reactions are adaptive, temporary and strictly individual. They are inherent only in one or several representatives of the species, subjected to training (training) or exposure to the natural environment. Conditioned reflexes are developed gradually, in the presence of a certain environment, and are a function of the normal, mature cortex of the cerebral hemispheres and lower parts of the brain. In this regard, conditioned reflexes are related to unconditioned ones, since they are a response of the same material substrate - nervous tissue.

If the conditions for the development of reflexes are constant from generation to generation, then the reflexes can become hereditary, that is, they can turn into unconditioned. An example of such a reflex is the opening of the beak of blind and fledgling chicks in response to the shaking of the nest by a bird flying in to feed them. Since shaking the nest is followed by feeding, which was repeated in all generations, the conditioned reflex becomes unconditioned. However, all conditioned reflexes are adaptive reactions to a new external environment. They disappear when the cerebral cortex is removed. Higher mammals and humans with damage to the cortex become deeply disabled and die in the absence of the necessary care.

Numerous experiments conducted by I.P. Pavlov showed that the basis for the development of conditioned reflexes is formed by impulses arriving along afferent fibers from extero- or interoreceptors. For their formation, the following conditions are necessary: ​​1) the action of an indifferent (future conditioned) stimulus must precede the action of an unconditioned stimulus. With a different sequence, the reflex is not developed or is very weak and quickly fades away; 2) for a certain time, the action of the conditioned stimulus must be combined with the action of the unconditioned stimulus, that is, the conditioned stimulus is reinforced by the unconditioned. This combination of stimuli should be repeated several times. In addition, a prerequisite for the development of a conditioned reflex is the normal function of the cerebral cortex, the absence of painful processes in the body and extraneous stimuli.
Otherwise, in addition to the reinforced reflex being developed, an indicative or reflex of the internal organs (intestines, bladder, etc.) will also occur.

An active conditioned stimulus always causes a weak focus of excitation in the corresponding area of ​​the cerebral cortex. The unconditioned stimulus that is connected (after 1-5 s) creates a second, stronger focus of excitation in the corresponding subcortical nuclei and the area of ​​the cerebral cortex, which distracts the impulses of the first (conditioned) weaker stimulus. As a result, a temporary connection is established between both foci of excitation of the cerebral cortex. With each repetition (i.e. reinforcement), this connection becomes stronger. The conditioned stimulus turns into a conditioned reflex signal. To develop a conditioned reflex, a conditioned stimulus of sufficient strength and high excitability of the cells of the cerebral cortex are necessary, which must be free from external stimuli. Compliance with the above conditions accelerates the development of a conditioned reflex.

Depending on the method of development, conditioned reflexes are divided into secretory, motor, vascular, reflexes of changes in internal organs, etc.

A reflex developed by reinforcing a conditioned stimulus with an unconditioned one is called a first-order conditioned reflex. Based on it, you can develop a new reflex. For example, by combining a light signal with feeding, a dog has developed a strong conditioned salivation reflex. If you give a bell (sound stimulus) before the light signal, then after several repetitions of this combination the dog begins to salivate in response to the sound signal. This will be a second-order reflex, or secondary, reinforced not by an unconditioned stimulus, but by a first-order conditioned reflex. When developing conditioned reflexes of higher orders, it is necessary that a new indifferent stimulus is turned on 10-15 s before the onset of the conditioned stimulus of a previously developed reflex. If the stimulus acts at intervals that are closer or combined, then a new reflex will not appear, and the previously developed one will fade away, as inhibition will develop in the cerebral cortex. Repeated repetition of jointly acting stimuli or a significant overlap of the time of action of one stimulus on another causes the appearance of a reflex to a complex stimulus.

A certain period of time can also become a conditioned stimulus for developing a reflex. People have a temporary reflex to feel hungry during the hours when they usually eat. Intervals can be quite short. In school-age children, a reflex for time is a weakening of attention before the end of the lesson (1-1.5 minutes before the bell). This is the result not only of fatigue, but also of the rhythmic functioning of the brain during training sessions. The reaction to time in the body is the rhythm of many periodically changing processes, for example, breathing, cardiac activity, awakening from sleep or hibernation, molting of animals, etc. Its occurrence is based on the rhythmic sending of impulses from the corresponding organs to the brain and back to the effector organs devices.