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?
Without conditioned reflex- this is an innate, stereotypical reaction of the body to the influence of the internal or environmental environment, inherited by offspring from parents. It remains in a person throughout his life. Reflex arcs pass through the head and cortex cerebral hemispheres does not take part in their education. 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 various factors, then there are different reflexes: food, defensive, orientation, sexual... Food ones 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, maintains the constancy 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. Irritant in in this case 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 are 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. He starts the mechanism, and repetition exposure to the stimulus allows the development of 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 signals external character. 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, consciousness are freed when performing operations that have reached automaticity and become a reality Everyday life. The most successful way to master skills is to systematically perform the exercise, timely correction of noticed errors, and knowledge ultimate goal 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 fairly 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. Besides, 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 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, general scheme unconditioned reflexes is as follows. Certain receptor nerve devices are affected by certain stimuli of internal or outside world body. As a result, the resulting irritation transforms the entire process into the so-called phenomenon nervous excitement. It is transmitted via nerve fibers(as if by wire) to the central nervous system, and from there it goes to a specific working organ, already turning into a specific process on cellular level this 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
Exceptional constancy of the underlying neural connection 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 shapes 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, pose and others). 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 to 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. Occurs abrupt change 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 the neuron is excited, the higher the frequency of the flow will be nerve impulses which it generates. However, if this flow exceeds certain limits, then a process will arise that will begin to interfere with the passage of excitation along neural circuit. The flow of impulses along the reflex arc of the spinal cord and brain is interrupted, resulting in inhibition that preserves executive bodies from complete exhaustion. What conclusion follows from this? Thanks to the inhibition of unconditioned reflexes, the body secretes from all possible options the most adequate, capable of protecting against excessive activities. This process also contributes to the exercise of so-called biological precautions.
Conditioned reflexes are reactions of the whole organism or any part of it to external or internal stimuli. They manifest themselves through the disappearance, weakening or strengthening of certain activities.
Conditioned reflexes are the body’s assistants, allowing it to quickly respond to any changes and adapt to them.
Story
The idea of a conditioned reflex was first put forward by the French philosopher and scientist R. Descartes. Somewhat later, the Russian physiologist I. Sechenov created and experimentally proved new theory concerning the body's reactions. For the first time in the history of physiology, it was concluded that conditioned reflexes are a mechanism that is activated not only; the entire nervous system is involved in its work. This allows the body to maintain a connection with the environment.
Studied by Pavlov. This outstanding Russian scientist was able to explain the mechanism of action of the cerebral cortex and cerebral hemispheres. At the beginning of the 20th century, he created the theory of conditioned reflexes. The treatise became a real revolution in physiology. Scientists have proven that conditioned reflexes are reactions of the body that are acquired throughout life, based on unconditioned reflexes.
Instincts
Certain reflexes of the unconditional type are characteristic of each type of living organism. They are called instincts. Some of them are quite complex. An example of this would be bees making honeycombs or birds making nests. Thanks to the presence of instincts, the body is able to optimally adapt to environmental conditions.
They are congenital. They are inherited. In addition, they are classified as species, since they are characteristic of all representatives of a certain species. Instincts are permanent and persist throughout life. They manifest themselves in response to adequate stimuli that are applied to a specific single receptive field. Physiologically, unconditioned reflexes are closed in the brainstem and at the level of the spinal cord. They manifest themselves through anatomically expressed
As for monkeys and humans, the implementation of most of the complex unconditioned reflexes is impossible without the participation of the cerebral cortex. When its integrity is violated, pathological changes in unconditioned reflexes occur, and some of them simply disappear.
Classification of instincts
Unconditioned reflexes are very strong. Only under certain conditions, when their manifestation becomes unnecessary, can they disappear. For example, the canary, domesticated about three hundred years ago, currently does not have the instinct to build nests. Distinguish the following types unconditioned reflexes:
Which is the body's reaction to a variety of physical or chemical stimuli. Such reflexes, in turn, can manifest locally (withdrawal of the hand) or be complex (flight from danger).
- Food instinct, which is caused by hunger and appetite. This unconditioned reflex includes whole chain successive actions - from searching for prey to attacking it and further eating it.
- Parental and sexual instincts associated with the maintenance and reproduction of the species.
A comfortable instinct that serves to keep the body clean (bathing, scratching, shaking, etc.).
- Orienting instinct, when the eyes and head are turned towards the stimulus. This reflex is necessary to preserve life.
- The instinct of freedom, which is especially clearly expressed in the behavior of animals in captivity. They constantly want to break free and often die, refusing water and food.
The emergence of conditioned reflexes
During life, acquired reactions of the body are added to the inherited instincts. They are called conditioned reflexes. They are acquired by the body as a result individual development. The basis for obtaining conditioned reflexes is life experience. Unlike instincts, these reactions are individual. They may be present in some members of the species and absent in others. In addition, a conditioned reflex is a reaction that may not persist throughout life. Under certain conditions, it is produced, consolidated, and disappears. Conditioned reflexes are reactions that can occur to various stimuli applied to different receptor fields. This is their difference from instincts.
The mechanism of the conditioned reflex closes at the level. If it is removed, then only instincts will remain.
The formation of conditioned reflexes occurs on the basis of unconditioned ones. To implement this process a certain condition must be met. In this case, any change in the external environment must be combined in time with internal state the body and is perceived by the cerebral cortex with a simultaneous unconditional reaction of the body. Only in this case does a conditioned stimulus or signal appear that contributes to the emergence of a conditioned reflex.
Examples
For the body’s reaction to occur, such as the release of saliva when knives and forks clink, as well as when an animal’s feeding cup is knocked (in humans and dogs, respectively), an indispensable condition is the repeated coincidence of these sounds with the process of providing food.
In the same way, the sound of a bell or the turning on of a light bulb will cause the dog's paw to flex if these phenomena have repeatedly occurred accompanied by electrical stimulation of the animal's leg, as a result of which an unconditioned type of flexion reflex appears.
The conditioned reflex is the child's hands being pulled away from the fire and subsequent crying. However, these phenomena will only occur if the type of fire, even once, coincides with a burn.
Reaction components
The body's reaction to irritation is a change in breathing, secretion, movement, etc. As a rule, unconditioned reflexes are quite complex reactions. That is why they contain several components at once. For example, the defensive reflex is accompanied not only by defensive movements, but also by increased breathing, accelerated activity of the heart muscle, and changes in blood composition. In this case, vocal reactions may also appear. As for the food reflex, there are also respiratory, secretory and cardiovascular components.
Conditioned reactions usually reproduce the structure of unconditioned ones. This occurs due to stimulation by stimuli of the same nerve centers.
Classification of conditioned reflexes
The responses acquired by the body to various stimuli are divided into types. Some of existing classifications have great value when solving not only theoretical, but also practical problems. One of the areas of application of this knowledge is sports activities.
Natural and artificial reactions of the body
There are conditioned reflexes that arise under the influence of signals characteristic of permanent properties unconditioned stimuli. An example of this is the sight and smell of food. Such conditioned reflexes are natural. They are characterized by rapid production and great durability. Natural reflexes, even in the absence of subsequent reinforcement, can be maintained throughout life. The importance of the conditioned reflex is especially great in the very first stages of the organism’s life, when it adapts to environment.
However, reactions can also be developed to a variety of indifferent signals, such as smell, sound, temperature changes, light, etc. Under natural conditions, they are not irritants. It is precisely such reactions that are called artificial. They are developed slowly and, in the absence of reinforcement, quickly disappear. For example, artificial conditioned human reflexes are reactions to the sound of a bell, touching the skin, weakening or increasing lighting, etc.
First and highest order
There are types of conditioned reflexes that are formed on the basis of unconditioned ones. These are first order reactions. There are also higher categories. Thus, reactions that are developed on the basis of already existing conditioned reflexes are classified as higher-order reactions. How do they arise? When developing such conditioned reflexes, the indifferent signal is reinforced with well-learned conditioned stimuli.
For example, irritation in the form of a bell is constantly reinforced by food. In this case, a first-order conditioned reflex is developed. On its basis, a reaction to another stimulus, for example, to light, can be fixed. This will become a second-order conditioned reflex.
Positive and negative reactions
Conditioned reflexes can influence the activity of the body. Such reactions are considered positive. The manifestation of these conditioned reflexes can be secretory or motor functions. If there is no activity of the body, then the reactions are classified as negative. For the process of adaptation to constantly changing environmental conditions, both one and the second species are of great importance.
At the same time, there is a close relationship between them, since when one type of activity is manifested, the other is certainly suppressed. For example, when the command “Attention!” is heard, the muscles are in a certain position. At the same time they slow down motor reactions(running, walking, etc.).
Education mechanism
Conditioned reflexes occur with the simultaneous action of a conditioned stimulus and an unconditioned reflex. In this case, certain conditions must be met:
The unconditioned reflex is biologically stronger;
- the manifestation of a conditioned stimulus is somewhat ahead of the action of instinct;
- the conditioned stimulus is necessarily reinforced by the influence of the unconditional;
- the body must be awake and healthy;
- the condition of the absence of extraneous stimuli producing a distracting effect is met.
The centers of conditioned reflexes located in the cerebral cortex establish a temporary connection (closure) with each other. In this case, the irritation is perceived by cortical neurons, which are part of the unconditioned reflex arc.
Inhibition of conditioned reactions
In order to ensure appropriate behavior the body and for better adaptation to environmental conditions, the development of conditioned reflexes alone will not be enough. An action in the opposite direction will be required. This is the inhibition of conditioned reflexes. This is the process of eliminating those reactions of the body that are not necessary. According to the theory developed by Pavlov, there are certain types cortical inhibition. The first of these is unconditional. It appears as a response to the action of some extraneous stimulus. There is also internal inhibition. It is called conditional.
External braking
This reaction received this name due to the fact that its development is facilitated by processes taking place in those areas of the cortex that do not participate in reflex activity. For example, an extraneous smell, sound, or change in lighting before the onset of the food reflex can reduce it or contribute to its complete disappearance. A new stimulus acts as an inhibitor for a conditioned response.
Eating reflexes can also be eliminated by painful stimuli. Inhibition of the body's reaction is facilitated by bladder overflow, vomiting, internal inflammatory processes, etc. All of them inhibit food reflexes.
Internal inhibition
It occurs when the received signal is not reinforced by an unconditioned stimulus. Internal inhibition of conditioned reflexes occurs if, for example, an animal is periodically turned on an electric light bulb in front of its eyes during the day without bringing food. It has been experimentally proven that saliva production will decrease each time. As a result, the reaction will fade away completely. However, the reflex will not disappear without a trace. He will simply slow down. This has also been proven experimentally.
Conditioned inhibition of conditioned reflexes can be eliminated the very next day. However, if this is not done, then the body’s reaction to this stimulus will subsequently disappear forever.
Types of internal braking
Several types of elimination of the body's reaction to stimuli are classified. Thus, the basis for the disappearance of conditioned reflexes, which are simply not needed under given specific conditions, is extinctive inhibition. There is another variety this phenomenon. This is discriminative or differentiated inhibition. Thus, an animal can distinguish the number of metronome beats at which food will be brought to it. This happens when this conditioned reflex is previously developed. The animal distinguishes between stimuli. The basis of this reaction is internal inhibition.
The value of eliminating reactions
Conditioned inhibition plays a significant role in the life of the body. Thanks to it, the process of adaptation to the environment occurs much better. Possibility of orientation in various difficult situations gives a combination of excitation and inhibition, which are two forms of a single nervous process.
Conclusion
Conditioned reflexes exist infinite set. They are the factor that determines the behavior of a living organism. With the help of conditioned reflexes, animals and humans adapt to their environment.
There are many indirect signs reactions of the body that have a signaling value. For example, an animal, knowing in advance that danger is approaching, organizes its behavior in a certain way.
The process of developing conditioned reflexes that relate to to the highest order, is a synthesis of temporary connections.
The basic principles and patterns manifested in the formation of not only complex but also elementary reactions are the same for all living organisms. Therefore important conclusion for philosophy and natural sciences that he cannot disobey general laws biology. In this regard, it can be studied objectively. However, it is worth keeping in mind that activities human brain has qualitative specificity and a fundamental difference from the work of the animal’s brain.
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 stimuli from the surrounding world, to which we were indifferent, can now acquire vital significance. During life, many conditioned reflexes are developed, which form the basis of our life experience. But this vital experience has meaning only for a given individual and is not inherited by its descendants.
In a separate category conditioned reflexes distinguish motor conditioned reflexes developed during our lives, i.e. skills or automated actions. The meaning of these conditioned reflexes is to master new motor skills and develop new forms of movements. During his life, a person masters many special motor skills related to his profession. Skills are the basis of our behavior. Consciousness, thinking, and attention are freed from performing those operations that have become automated and become skills of everyday life. Most successful path Mastering skills means 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.
The term “reflex” was introduced by the French scientist R. Descartes in the 17th century. But for the sake of explanation mental activity it was applied 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 - natural reserve ready-made, stereotypical reactions of the body. They arose as a result of a long evolutionary development this type of animal. 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. 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 - zone of analysis of oral verbal signals (Wernicke's center), 4 - area auditory analyzer, 5 - analysis of written verbal signals, 6 - area of the visual analyzer
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, surrounding the animal in natural conditions and in themselves not having vital important, preceding in the animal's experience food or danger, the satisfaction of others 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 - excitation from a food stimulus is associated with a previous indifferent stimulus (light bulb);
- c - the light of the light bulb became a signal possible appearance food: a conditioned reflex has developed to it
A conditioned reflex is developed on the basis of any of unconditional reactions. Reflexes to unusual signals that do not occur in a natural environment are called artificial conditioned. IN laboratory conditions You can 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, principle of synthesis 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, historically turning point in understanding 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.
Higher nervous activity is a system that allows the human and animal body to adapt to variable conditions external environment. Evolutionarily, vertebrates have developed a number of innate reflexes, but for successful development and their existence is not enough.
In the process of individual development, new adaptive reactions are formed - these are conditioned reflexes. Outstanding domestic scientist I.P. Pavlov is the founder of the doctrine of unconditioned and conditioned reflexes. He formed the conditioned reflex theory, which states that the acquisition of a conditioned reflex is possible through the action of a physiologically indifferent irritation on the body. As a result, more a complex system reflex activity.
I.P. Pavlov - the founder of the doctrine of unconditioned and conditioned reflexes
An example of this is Pavlov's study of dogs that salivated in response to a sound stimulus. Pavlov also showed that innate reflexes are formed at the level of subcortical structures, and new connections are formed in the cerebral cortex throughout the life of an individual under the influence of constant irritations.
Conditioned reflexes
Conditioned reflexes are formed on the basis of unconditional ones, in the process of individual development of the organism, against the background of a changing external environment.
Reflex arc The conditioned reflex consists of three components: afferent, intermediate (intercalary) and efferent. These links carry out the perception of irritation, the transmission of impulses to cortical structures and the formation of a response.
The reflex arc of the somatic reflex performs motor functions (for example, flexion movement) and has the following reflex arc:
The sensitive receptor perceives the stimulus, then the impulse goes to the dorsal horns spinal cord, where the interneuron is located. Through it, the impulse is transmitted to the motor fibers and the process ends with the formation of movement - flexion.
A necessary condition for the development of conditioned reflexes is:
- The presence of a signal that precedes the unconditional;
- the stimulus that will cause the catch reflex must be inferior in strength to the biologically significant effect;
- normal functioning of the cerebral cortex and the absence of distractions are mandatory.
Conditioned reflexes are not formed instantly. They are formed over a long period of time under constant observance of the above conditions. In the process of formation, the reaction either fades away, then resumes again, until stable reflex activity occurs.
An example of developing a conditioned reflex Classification of conditioned reflexes:
- A conditioned reflex formed on the basis of the interaction of unconditioned and conditioned stimuli is called first order reflex.
- Based on the classical acquired reflex of the first order, it is developed second order reflex.
Thus, a third-order defensive reflex was formed in dogs, the fourth could not be developed, and the digestive reflex reached the second. In children, conditioned reflexes of the sixth order are formed, in an adult up to the twentieth.
The variability of the external environment leads to the constant formation of many new behaviors necessary for survival. Depending on the structure of the receptor that perceives the stimulus, conditioned reflexes are divided into:
- Exteroceptive– irritation is perceived by body receptors and predominates among reflex reactions (taste, tactile);
- intraceptive– are called upon action on internal organs(changes in homeostasis, blood acidity, temperature);
- proprioceptive– are formed by stimulating the striated muscles of humans and animals, providing motor activity.
There are artificial and natural acquired reflexes:
Artificial occur under the influence of stimulation that has no connection with the unconditioned stimulus (sound signals, light stimulation).
Natural are formed in the presence of a stimulus similar to the unconditioned one (the smell and taste of food).
Unconditioned reflexes
These are innate mechanisms that ensure the preservation of the integrity of the body, the homeostasis of the internal environment and, most importantly, reproduction. Congenital reflex activity is formed in the spinal cord and cerebellum and is controlled by the cerebral cortex. Typically, they last a lifetime.
Reflex arcs hereditary reactions are laid down before a person is born. Some reactions are characteristic of a certain age and then disappear (for example, in small children - sucking, grasping, searching). Others do not manifest themselves at first, but appear (sexually) after a certain period of time.
Unconditioned reflexes are characterized by the following features:
- Occur regardless of the consciousness and will of a person;
- specific - manifested in all representatives (for example, coughing, salivation at the smell or sight of food);
- endowed with specificity - they appear when exposed to a receptor (the reaction of the pupil occurs when a beam of light is directed to photosensitive areas). This also includes salivation, secretion of mucous secretions and enzymes digestive system when food enters the mouth;
- flexibility - for example, different foods lead to the secretion of a certain amount and variety chemical composition saliva;
- On the basis of unconditioned reflexes, conditioned ones are formed.
Unconditioned reflexes are needed to fulfill the needs of the body; they are constant, but as a result of illness or bad habits may disappear. So, when the iris of the eye is diseased, when scars form on it, the reaction of the pupil to light exposure disappears.
Classification of unconditioned reflexes
Congenital reactions are classified into:
- Simple(quickly remove your hand from the hot object);
- complex(maintaining homeostasis in situations of increased CO 2 concentration in the blood by increasing the frequency of respiratory movements);
- the most complex(instinctive behavior).
Classification of unconditioned reflexes according to Pavlov
Pavlov divided innate reactions into food, sexual, protective, orientation, statokinetic, homeostatic.
TO food refers to the secretion of saliva at the sight of food and its entry into the digestive tract, of hydrochloric acid, gastrointestinal motility, sucking, swallowing, chewing.
Protective accompanied by contraction of muscle fibers in response to an irritating factor. Everyone is familiar with the situation when a hand reflexively withdraws from a hot iron or sharp knife, sneezing, coughing, watery eyes.
Approximate occur when sudden changes occur in nature or in the body itself. For example, turning the head and body towards sounds, turning the head and eyes towards light stimuli.
Genital are associated with reproduction, preservation of the species, this also includes parental (feeding and caring for offspring).
Statokinetic provide upright posture, balance, and body movement.
Homeostatic– independent regulation blood pressure, vascular tone, respiratory rate, heart rate.
Classification of unconditioned reflexes according to Simonov
Vital to maintain life (sleep, nutrition, saving energy) depend only on the individual.
Role-playing arise upon contact with other individuals (procreation, parental instinct).
The need for self-development(desire for individual growth, to discover new things).
Innate reflexes are activated when necessary due to a short-term violation of internal constancy or variability in the external environment.
Comparison table between conditioned and unconditioned reflexes
| Comparison of the characteristics of conditioned (acquired) and unconditioned (innate) reflexes | |
|---|---|
| Unconditional | Conditional |
| Congenital | Acquired during life |
| Present in all representatives of the species | Individual for each organism |
| Relatively constant | Appear and disappear with changes in the external environment |
| Formed at the level of the spinal cord and medulla oblongata | Carried out through the work of the brain |
| Laid in utero | Developed against the background of innate reflexes |
| Occurs when a stimulus acts on certain receptor areas | Manifest under the influence of any stimulus that is perceived by the individual |
Higher nervous activity operates in the presence of two interrelated phenomena: excitation and inhibition (congenital or acquired).
Braking
External unconditional inhibition(congenital) is carried out by the action of a very strong irritant on the body. The termination of the conditioned reflex occurs due to the activation of nerve centers under the influence of a new stimulus (this is transcendental inhibition).
When the organism under study is exposed to several stimuli at the same time (light, sound, smell), the conditioned reflex fades, but over time the indicative reflex is activated and the inhibition disappears. This type of braking is called temporary.
Conditioned inhibition(acquired) does not arise on its own, it must be developed. There are 4 types of conditioned inhibition:
- Extinction (disappearance of a persistent conditioned reflex without constant reinforcement by the unconditioned);
- differentiation;
- conditional brake;
- delayed braking.
Inhibition is a necessary process in our life. In its absence, many unnecessary reactions would occur in the body that would not be beneficial.
Example of external inhibition (dog's reaction to a cat and the SIT command) The meaning of conditioned and unconditioned reflexes
Unconditioned reflex activity is necessary for the survival and preservation of the species. A good example serves the birth of a child. In a new world for him, many dangers await him. Thanks to the presence of innate reactions, the cub can survive in these conditions. Immediately after birth, the respiratory system is activated, the sucking reflex provides nutrients, touching sharp and hot objects is accompanied by an instant withdrawal of the hand (manifestation of defensive reactions).
For further development and existence we have to adapt to environmental conditions, conditioned reflexes help with this. They ensure rapid adaptation of the body and can be formed throughout life.
The presence of conditioned reflexes in animals gives them the ability to quickly respond to the voice of a predator and save their lives. When a person sees food, he performs conditioned reflex activity, salivation begins, production gastric juice for quick digestion of food. The sight and smell of some objects, on the contrary, signals danger: the red cap of the fly agaric, the smell of spoiled food.
The importance of conditioned reflexes in the everyday life of humans and animals is enormous. Reflexes help you navigate the terrain, get food, and escape from danger while saving your life.