During the evolutionary and social development the person has developed natural system protection from adverse environmental factors, i.e. from dangers. Its basis is the nervous system. Thanks to it, the body communicates with the external environment (light, sound, smell, mechanical influences) and a variety of information about processes inside and outside the body. The body's response to stimulation, carried out and controlled by the central nervous system, is called a reflex, and all activities nervous system- reflex. In the diverse reflex activity there are innate unconditioned reflexes, which are inherited and persist throughout the life of the organism.

Unconditioned human reflexes are varied. For example, withdrawing a hand in response to a skin burn, closing the eyes when there is a danger of damaging them, profuse production of tears under the influence of substances that irritate the eyes, etc. These and many other reflexes are called defensive.

A special place among without conditioned reflexes The orienting reflex plays a role in ensuring safety. It appears in response to a new stimulus: a person becomes alert, listens, turns his head, squints his eyes, and thinks. The orienting reflex ensures the perception of an unfamiliar stimulus.

Unconditioned reflexes are a hereditary “program” of behavior. They provide normal interaction only with a stable environment. However, man lives in an extremely changeable, mobile, diverse environment. Unconditioned reflexes as constant connections are not enough to ensure a flexible response in a changing environment. It is necessary to supplement them with temporary flexible connections. Such connections are called conditioned reflexes.

Conditioned reflexes are formed on the basis of individual experience. Since the acquisition of individual experience is learning, the formation of conditioned reflexes is one of the types of learning.

Conditioned reflexes formed during the learning process allow the body to adapt more flexibly to specific environmental conditions and form the basis for the development of a person’s habits and entire lifestyle.

The adaptive value of conditioned reflexes is enormous. Thanks to them, a person can take action in advance necessary actions for their own protection, focusing on signs of possible danger, without seeing the danger itself. Conditioned stimuli have a signaling character. They warn of danger.

All immediate sensations, perceptions and corresponding human reactions are carried out on the basis of unconditioned and conditioned reflexes. However, in the specific conditions of the social environment, a person orients himself and reacts not only to immediate stimuli. For a person, the signal of any stimulus is the word denoting it, and its semantic content. Words spoken, heard and visible are signals, symbols of specific objects and environmental phenomena. The word man denotes everything that he perceives with the help of his senses.

Words, like other environmental factors (physical, chemical and biological), can be indifferent to human health, can have a beneficial effect, or can be harmful - even fatal outcome(suicide).

1. 1. Introduction3
2. 2. Physiology of unconditioned reflexes3
3. 3. Classification of unconditioned reflexes5
4. 4. The importance of unconditioned reflexes for the body7
5. 5. Conclusion7

References8

Introduction

Unconditioned reflexes are hereditarily transmitted (innate), inherent in the entire species. They perform a protective function, as well as the function of maintaining homeostasis.

Unconditioned reflexes are an inherited, unchangeable reaction of the body to external and internal signals, regardless of the conditions for the occurrence and course of reactions. Unconditioned reflexes ensure the body's adaptation to constant environmental conditions. They are a species behavioral characteristic. The main types of unconditioned reflexes: food, protective, orienting.

An example of a defensive reflex is the reflexive withdrawal of the hand from a hot object. Homeostasis is maintained, for example, by a reflex increase in breathing when there is excess carbon dioxide in the blood. Almost every part of the body and every organ is involved in reflex reactions.

Physiology of unconditioned reflexes

An unconditioned reflex is an innate response of the body to irritation with the obligatory participation of the central nervous system (CNS). In this case, the cerebral cortex does not directly participate, but exercises its highest control over these reflexes, which allowed I.P. Pavlov to assert the presence of a “cortical representation” of each unconditioned reflex. Unconditioned reflexes are the physiological basis:

1. Human species memory, i.e. congenital, inherited, constant, common to the entire human species;

2. Inferior nervous activity(NND). NND from the point of view of unconditioned reflexes is an unconditioned reflex activity that provides the body with the unification of its parts into a single functional whole. Another definition of NND. NND is a set of neurophysiological processes that ensure the implementation of unconditioned reflexes and instincts.

The simplest neural networks, or arcs (according to Sherrington), involved in unconditioned reflexes, are closed in the segmental apparatus of the spinal cord, but can also be closed higher (for example, in the subcortical ganglia or in the cortex). Other parts of the nervous system are also involved in reflexes: brain stem, cerebellum, cortex cerebral hemispheres.

The arcs of unconditioned reflexes are formed at the time of birth and remain throughout life. However, they can change under the influence of illness. Many unconditioned reflexes appear only at a certain age; Thus, the grasping reflex characteristic of newborns fades away at the age of 3-4 months.

There are monosynaptic (involving the transmission of impulses to the command neuron through one synaptic transmission) and polysynaptic (involving the transmission of impulses through chains of neurons) reflexes.

Approximate unconditioned reflexes, occurring with the direct participation of the cerebral cortex, are physiological mechanisms of human cognitive activity and involuntary attention. In addition, the extinction of orientation reflexes constitutes the physiological basis of addiction and boredom. Habituation is the extinction of the orienting reflex: if the stimulus is repeated many times and does not have special significance for the body, the body stops reacting to it, addiction develops. So, a person living on a noisy street gradually gets used to the noise and no longer pays attention to it.

Instincts are a form of innate behavior. Their physiological mechanism is a chain of innate unconditioned reflexes, into which, under the influence of individual life conditions, links of acquired conditioned reflexes can be “woven together.”

Rice. 1. Scheme of organization of instinctive behavior: S - stimulus, P - reception, P - behavioral act; the dotted line is the modulating influence, the solid line is the activity of the modulating system as an evaluative authority.

Reflection as the essence of the psyche occurs on different levels. There are three levels of brain activity: specific, individual and socio-historical. Reflection at the species level is carried out by unconditioned reflexes.

In development theoretical foundations The concept of “drive and drive-reflex” by the Polish physiologist and psychologist J. Konorski played a significant role in the organization of behavior. According to the theory of Yu. Konorsky, brain activity is divided into executive and preparatory, and all reflex processes fall into two categories: preparatory (incentive, drive, motivational) and executive (consummatory, consummatory, reinforcing).

Executive functioning involves many specific responses to many specific stimuli, so this activity is provided by the cognitive or gnostic system, which includes the stimulus recognition system. Preparatory activities associated with less specific reactions and in to a greater extent controlled by the internal needs of the body. It is anatomically and functionally different from the system responsible for perception and cognitive activity, training, and is called by Yu. Konorsky an emotive, or motivational system.

The cognitive and emotive systems are served by different brain structures.

Most unconditioned reflexes are complex reactions that include several components. So, for example, with an unconditioned defensive reflex caused in a dog by strong electrodermal irritation of the limb, along with defensive movements, breathing also increases and increases, cardiac activity accelerates, vocal reactions appear (squealing, barking), the blood system changes (leukocytosis, thrombocytosis and etc.). The food reflex is also distinguished by its motor (grabbing food, chewing, swallowing), secretory, respiratory, cardiovascular and other components.

So, the most complex unconditioned reflexes are an innate holistic behavioral act, a systemic morphophysiological formation that includes stimulating and reinforcing components (preparatory and executive reflexes). Instinctive behavior is realized by external and internal determinants by “evaluating” the relationships between significant components of the environment and the internal state of the organism, determined by the actualized need.

Classification of unconditioned reflexes

The entire set of unconditioned and conditioned reflexes formed on their basis is usually divided into a number of groups according to their functional significance. The main ones are nutritional, defensive, sexual, statokinetic and locomotor, orientation, maintaining homeostasis and some others. Food reflexes include reflex acts of swallowing, chewing, sucking, salivation, secretion of gastric and pancreatic juice, etc. Defensive reflexes are reactions to eliminate damaging and painful stimuli. The group of sexual reflexes includes all reflexes associated with sexual intercourse; This group also includes the so-called parental reflexes associated with feeding and nursing the offspring. Statokinetic and locomotor reflexes are reflex reactions of maintaining a certain position and movement of the body in space. Reflexes that support the preservation of homeostasis include thermoregulatory, respiratory, cardiac and those vascular reflexes that help maintain constancy blood pressure, and some others. The orienting reflex occupies a special place among unconditioned reflexes. This is a reflex to novelty.

It occurs in response to any fairly quickly occurring fluctuation in the environment and is expressed externally in alertness, listening to a new sound, sniffing, turning the eyes and head, and sometimes the whole body towards the emerging light stimulus, etc. The implementation of this reflex provides better perception of the acting agent and has important adaptive significance. This reaction is innate and does not disappear when complete removal cerebral cortex in animals; it is also observed in children with underdeveloped cerebral hemispheres - anencephals. The difference between the orienting reflex and other unconditioned reflex reactions is that it fades away relatively quickly with repeated applications of the same stimulus. This feature of the orientation reflex depends on the influence of the cerebral cortex on it.

Rice. 1. Comparison of the most complex unconditioned reflexes (instincts) of higher animals with human needs: double arrows - phylogenetic connections of the most complex reflexes of animals with human needs, dotted - the interaction of human needs, solid - the influence of needs on the sphere of consciousness

The importance of unconditioned reflexes for the body

The meaning of unconditioned reflexes:

♦ maintaining consistency internal environment(homeostasis);

♦ maintaining the integrity of the body (protection from damaging factors external environment);

♦ reproduction and preservation of the species as a whole.

Conclusion

Unconditioned reflexes, the formation of which is completed in postnatal ontogenesis, are genetically predetermined and strictly adjusted to certain, appropriate this species environmental conditions.

Congenital reflexes are characterized by a stereotypical species-specific sequence of implementation of a behavioral act. They arise at their first need, when a stimulus “specific” to each of them appears, thereby ensuring the consistency of fulfillment of the most vital important functions organism regardless of random, transient environmental conditions. Characteristic feature unconditioned reflexes is that their implementation is determined by both internal determinants and an external stimulus program.

As P.V. notes Simonov, the definition of an unconditioned reflex as hereditary, unchangeable, the implementation of which is machine-like and independent of the achievements of its adaptive goal, is usually exaggerated. Its implementation depends on the existing functional state of the animal and correlates with the dominant at the moment need. It may fade or intensify.

Satisfying a variety of needs would have been impossible if, in the process of evolution, a specific overcoming reaction, the freedom reflex, had not arisen. The fact that the animal resists coercion, attempts to limit it motor activity, Pavlov looked much deeper than just a type of defensive reaction. The freedom reflex is an independent active form of behavior for which an obstacle serves as no less an adequate stimulus than food for food search, pain for a defensive reaction, and a new and unexpected stimulus for an orienting reflex.

References

1. 1. Bizyuk. A.P. Fundamentals of neuropsychology. Textbook for universities. Publishing house Rech. - 2005
2. 2. Danilova, A.L. Krylova Physiology of higher nervous activity. - Rostov n/a: “Phoenix”, 2005. - 478
3. 3. Psychophysiology /ed. Alexandrova Yu.I. St. Petersburg, publishing house "Peter" 2006
4. 4. Tonkonogiy I.M., Pointe A. Clinical neuropsychology. 1st edition, Publisher: PETER, PUBLISHING HOUSE, 2006
5. 5. Shcherbatykh Yu.V. Turovsky Ya.A. Anatomy of the central nervous system for psychologists: Tutorial. St. Petersburg: Peter, 2006. - 128 p.

Higher nervous activity (HNA)

Higher nervous activity (HNA) is a complex and interconnected set of nervous processes that underlie human behavior. GND ensures maximum human adaptability to environmental conditions.

GND is based on complex electrical and chemical processes occurring in the cells of the cerebral cortex. By 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 for abstract logical thinking.

The creation of the doctrine of higher nervous activity began with 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 sensory organs and continue in the brain in the form of certain nervous phenomena that lead to the launch of behavioral reactions.

A reflex is the body's response to stimulation, occurring with the participation of the nervous system.

THEM. Sechenov argued that brain reflexes include three parts:

• The first, initial link is stimulation in the senses caused by external influences.
• The second, central link is the processes of excitation and inhibition occurring in the brain. On their basis, mental phenomena arise (sensations, ideas, feelings, etc.).
• The third, final link is the movements and actions of a person, i.e. his behavior. All these links are interconnected and condition each other.

Sechenov concluded that the brain is an area of ​​continuous change of 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, which people inherit from their ancestors, and acquired ones, which arise throughout life as a result of learning. I.M. Sechenov’s assumptions and conclusions were ahead of their time.

The successor of the ideas of I.M. Sechenov became I.P. Pavlov.

Ivan Petrovich Pavlov divided all reflexes that arise in the body into unconditional and conditional.

Unconditioned reflexes

Unconditioned reflexes are inherited by offspring from their parents, persist throughout the life of the organism and are reproduced from generation to generation ( permanent). They are characteristic of all individuals of a certain species, i.e. group.

In unconditioned reflexes constant reflex arcs, which pass through the brain stem or through the spinal cord (for their implementation participation of the cortex is not necessarycerebral hemispheres).

There are food, defensive, sexual and indicative unconditioned reflexes.

• Food: separation of digestive juices in response to irritation of oral receptors, swallowing, sucking movements in a newborn.
• Defensive: withdrawal of a hand that has touched a hot object or when experiencing painful irritation, coughing, sneezing, blinking, etc.
• Genital: The process of reproduction is associated with sexual reflexes.
• Approximate(I.P. Pavlov called it the “what is this?” reflex) ensures the perception of an unfamiliar stimulus. An indicative reflex appears in response to a new stimulus: a person becomes alert, listens, turns his head, squints his eyes, and thinks.

Thanks to unconditioned reflexes, the integrity of the body 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 feeds and protects her child, birds build nests - these are examples of instincts.

Conditioned reflexes

Along with hereditary (unconditioned) reflexes, there are reflexes that are acquired by every person throughout life. Such reflexes individual, and certain conditions are necessary for their formation, which is why they were called conditional.

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

Signs of comparison	Unconditioned reflexes	Conditioned reflexes
Inheritance	Congenital, passed on from parents to offspring	Acquired by the body during life, they are not inherited
Species specificity		Individual
Stimulus	Carried out in response to an unconditioned stimulus	Carried out in response to any irritation perceived by the body; are formed on the basis of unconditioned reflexes
Meaning in life	Life without them is usually impossible	Promote the survival of the organism in constantly changing environmental conditions
Duration of existence of a reflex arc	Have ready and permanent reflex arcs	They do not have ready-made and permanent reflex arcs; their arcs are temporary and form under certain conditions
Reflex centers	They are carried out at the level of the spinal cord, brain stem and subcortical nuclei, i.e. reflex arcs pass through the lower levels of the central nervous system	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.

PROGRESS OF THE LESSON

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.

2. For experiments on studying conditioned reflexes, two dogs were taken. One of them was given a drink large number water. Then the research began. At first, conditioned reflexes were carried out normally in both dogs. But after some time, the conditioned reflexes disappeared in the dog that drank water. Random external influences while they were absent. What is the reason for the inhibition of conditioned reflexes?

3. As is known, a conditioned reflex can be developed to the action of almost any indifferent stimulus. One dog in the laboratory of I.P. Pavlov never managed to develop a conditioned reflex to the gurgling of water. Try to explain the lack of results in this case.

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

Equipment: rubber bulb for pumping air, metronome.

PROGRESS OF WORK

1. Turn on the metronome at a rhythm of 120 beats per minute and on the 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 the mechanisms of development of conditioned reflexes, various types congenital and acquired inhibition.

PROGRESS OF THE LESSON

I. Test of knowledge

Working with cards

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. Infant when he 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.
B. Food in the mouth.
B. Turning on the light during feeding.
D. Salivation of food in the mouth.
D. Secretion of saliva to the light of a light bulb.

Answers: 1 – B, 2 – A, 3 – D, 4 – D, 5 – B, 6 – C, 7 – A, 8 – B, 9 – C.

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 excitement?

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 environment.

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

Distinguish the following types braking. Unconditional braking: beyond (protective); external; innate reflexes. Conditional braking: extinct; differentiation; delayed.

3. Types of unconditional (congenital) inhibition and their characteristics

In the process of life, the body is constantly exposed to one or another irritation from the outside or from the inside. Each of these irritations is capable of causing a corresponding reflex. If all these reflexes could be realized, then the body’s activity would be chaotic. However, this does not happen. On the contrary, reflex activity is characterized by consistency and orderliness: with the help of unconditional inhibition, the most important reflex for the body at a given moment delays all other, secondary reflexes for the duration of its implementation.

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

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 considering 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. But the French scientist believed that this was not psychological phenomenon. He considered reflexes as part of objective natural science knowledge, while psychology at that time was considered not a science, because it dealt only with subjective reality and was not subject to objective experiment.

The very concept of “reflex” was introduced in the second half of the 19th century by the Russian physiologist I.M. Sechenov. He proved that reflex activity constitutes a single principle of operation of the entire central nervous system. The scientist demonstrated that the initial cause of a mental phenomenon or human action is determined by the influence of the external environment or irritation of the nervous system within the body.

And if the sense organs do not experience irritation, and sensitivity is lost, mental life freezes. Let's remember famous expression: “get tired to the point of losing your senses.” And indeed, when we are very tired, we, as a rule, do not dream and become almost insensitive to external stimuli: noise, light, even pain.

Sechenov’s research was continued by I.P. Pavlov. He came to the conclusion that there are innate reflexes, the occurrence of which does not require any special conditions, and acquired ones, which arise during the body’s adaptation to the external environment.

Surely many will now remember Pavlov’s famous dog. And not in vain: while studying digestion in animals, the scientist noticed that in the experimental dogs, salivation began not when food was served, but already at the sight of the researcher’s assistant, who usually brought food.

If the release of saliva when food is served is a typical unconditioned reflex, and it is characteristic of all dogs, then saliva even at the sight of a helper is a typical conditioned reflex developed in individual animals. Hence the main difference between the two types: genetic or occurrence under the influence of the environment. In addition, unconditioned and conditioned reflexes differ in a number of indicators.

• Unconditioned are present in all individuals of the species, regardless of their living conditions; conditional, on the contrary, arise under the influence of the individual living conditions of the organism (this difference is clear from the name of each type).
• Unconditioned reactions are the foundation on which conditioned ones can be formed, but they need constant reinforcement.
• Reflex arcs of unconditioned reflexes are closed in the lower parts of the brain, as well as in the spinal cord. The conditioned arcs are formed in the cerebral cortex.
• Unconditioned reflex processes remain unchanged throughout a person’s life, although they can be somewhat transformed in the case of a serious illness. Conditional - arise and disappear. In other words, in one case the reflex arcs are permanent, in the other they are temporary.

From these differences it is easy to add up general characteristics unconditioned reflexes: they are hereditary, unchangeable, inherent in all representatives of the species and support the life of the organism in constant environmental conditions.

Where do they arise?

As already mentioned, both conditioned and unconditioned reflexes are possible thanks to the work of the central nervous system. Its most important components are the brain and spinal cord. As an example of an unconditioned reflex for which the spinal cord is responsible, we can cite the well-known knee reflex.

The doctor lightly hits the specific place, which causes involuntary extension of the lower leg. Normally, this reflex should be of average severity, but if it is too weak or too strong, this is most likely evidence of pathology.

Unconditioned reflexes of the brain are numerous. In the lower parts of this organ there are various reflex centers. So, if you move up from the spinal cord, the first is the medulla oblongata. Sneezing, coughing, swallowing, salivation - these reflex processes are possible precisely thanks to the work of the medulla oblongata.

Under the control of the midbrain - reactions that occur in response to visual or auditory impulses. This includes constriction or dilation of the pupil depending on the amount of light falling on it, a reflexive turn towards the source of sound or light. The effect of such reflexes extends only to unfamiliar stimuli.

That is, for example, when there are numerous sharp sounds, a person will each time turn to a new place where the noise originates, rather than continue to listen, trying to understand where the first sound came from. The so-called unconditioned reflex of straightening the posture is closed through the intermediate part of the brain. These are the muscle contractions with which our body responds to changes in posture; they allow the body to be held in a new position.

Classification

Classification of unconditioned reflexes is carried out according to different criteria. For example, there is a division that is understandable even to a non-specialist into simple, complex and extremely complex.

The example given at the beginning of the text about pulling your hand away from the kettle is a simple unconditioned reflex. Complex problems include, for example, sweating. And if we are dealing with a whole chain of simple actions, then we are already talking about a group of the most complex ones: say, self-preservation reflexes, caring for offspring. This set of behavior programs is usually called instinct.

The classification is quite simple based on the body’s relationship to the stimulus. If you rely on it, unconditioned reflex reactions are divided into positive (search for food by smell) and negative (desire to escape from the source of noise).

By biological significance The following types of unconditioned reflexes are distinguished:

• Nutritional (swallowing, sucking, salivation).
• Sexual (sexual arousal).
• Defensive or protective (the same withdrawal of hands or the desire to cover the head with hands if a person thinks that a blow is about to follow).
• Indicative (the desire to identify unfamiliar stimuli: turning your head towards a sharp sound or touch). They were already discussed when we talked about the reflex centers of the midbrain.
• Locomotor, that is, serving for movement (support the body in a certain position in space).

Very often in scientific literature there is a classification proposed by the Russian scientist P. V. Simonov. He divided all unconditioned reflexes into three groups: vital, role and self-development reflexes.

Vital (from the Latin vitalis - “vital”) are directly related to the preservation of the very life of an individual. This is a food, defensive, effort-saving reflex (if the result of the actions is the same, what takes away less strength), regulation of sleep and wakefulness.

If the corresponding need is not satisfied, the physical existence of the organism ceases; another representative of the species is not needed to implement the reflex - these are the signs that unite all the reactions of this group.

Role-playing can be carried out, on the contrary, only through contact with another individual. These primarily include parental and sexual reflexes. The last group includes such reflexes as play, exploration, and the reflex of imitation of another individual.

Of course, there are other classification options, as well as other views on the methods of division given here. And this is not surprising: there is rarely unanimity among scientists.

Features and meaning

As we have already said, the reflex arcs of unconditioned reflexes are constant, but they themselves can be active in different periods human life. For example, sexual reflexes appear when the body reaches a certain age. Other reflex processes, on the contrary, fade away after a certain period of time. Suffice it to recall the unconscious grasping of a baby by an adult’s finger when pressing on his palm, which disappears with age.

The importance of unconditioned reflexes is enormous. They help to survive not only an individual organism, but the entire species. They are most significant in the early stages of a person’s life, when knowledge about the world has not yet been accumulated and the child’s activities are guided by reflex processes.

Unconditioned reflexes begin to work from the very moment of birth. Thanks to them, the body does not die during a sharp transition to new conditions of existence: adaptation to a new type of breathing and nutrition occurs instantly, and the mechanism of thermoregulation is gradually established.

Moreover, according to recent research, certain unconditioned reflexes are carried out even in the womb (for example, sucking). With age, more and more conditioned reflexes are added to the unconditioned ones, which allow a person to better adapt to a changing environment. Author: Evgenia Bessonova