Unconditioned reflexes - what is it and what is their role? Conditioned reflex examples.

Human behavior is associated with conditionally unconditioned reflex activity and is a higher nervous activity, the result of which is a change in the ratio of the organism with the external environment.

In contrast to higher nervous activity, lower nervous activity consists of a set of reactions aimed at unification, integration of functions within the body.

Higher nervous activity manifests itself in the form of complex reflex reactions, carried out with the obligatory participation of the cerebral cortex and the subcortical formations closest to it.

For the first time, the idea of ​​the reflex nature of the activity of the brain was widely and in detail developed by the founder of Russian physiology, I. M. Sechenov, in his book "Reflexes of the Brain". The ideological setting of this classic work is expressed in the original title, changed under the influence of censorship: "An attempt to introduce physiological foundations into mental processes." Before I. M. Sechenov, physiologists and neurologists did not even dare to raise the question of the possibility of an objective, purely physiological analysis of mental processes. The latter remained completely at the mercy of subjective psychology.

The ideas of I. M. Sechenov were brilliantly developed in the remarkable works of I. P. Pavlov, who opened the way for an objective experimental study of the functions of the cerebral cortex and created a coherent theory of higher nervous activity.

I. P. Pavlov showed that while in the underlying parts of the central nervous system - the subcortical nuclei, the brain stem, the spinal cord - reflex reactions are carried out along innate, hereditarily fixed nerve pathways, in the cerebral cortex, nerve connections are developed and created in the process individual life of animals and humans, as a result of a combination of countless stimuli acting on the body.

The discovery of this fact made it possible to divide the entire set of reflex reactions occurring in the body into two main groups: unconditioned and conditioned reflexes.

Conditioned reflexes

• these are reactions acquired by the body in the process of individual development on the basis of "life experience"
• are individual: some representatives of the same species may have them, while others may not
• are unstable and, depending on certain conditions, they can develop, gain a foothold or disappear; this is their property and is reflected in their very name
• can form in response to a wide variety of stimuli applied to various receptive fields
• closed at the level of the cortex. After the removal of the cerebral cortex, the developed conditioned reflexes disappear and only unconditioned reflexes remain.
• carried out through functional temporary connections

Conditioned reflexes are developed on the basis of unconditioned reflexes. For the formation of a conditioned reflex, it is necessary to combine the time of any change in the external environment and the internal state of the organism, perceived by the cerebral cortex, with the implementation of one or another unconditioned reflex. Only under this condition does a change in the external environment or the internal state of the organism become an irritant of the conditioned reflex - a conditioned stimulus, or signal. The stimulus that causes an unconditioned reflex - an unconditioned stimulus - must, during the formation of a conditioned reflex, accompany the conditioned stimulus, reinforce it.

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

With the coincidence and combination of conditioned and unconditioned stimuli, a connection is established between various neurons in the cortex of the cerebral hemispheres, and a closure process occurs between them.

Unconditioned reflexes

• these are congenital, hereditary reactions of the body
• are specific, i.e. characteristic of all representatives of a given species
• relatively constant, usually persisting throughout life
• carried out in response to adequate stimuli applied to one specific receptive field
• close at the level of the spinal cord and brain stem
• are carried out through a phylogenetically fixed, anatomically expressed reflex arc.

It should be noted, however, that in humans and monkeys, which have a high degree of corticalization of functions, many complex unconditioned reflexes are carried out with the obligatory participation of the cerebral cortex. This is proved by the fact that its lesions in primates lead to pathological disturbances of unconditioned reflexes and the disappearance of some of them.

It should also be emphasized that not all unconditioned reflexes appear immediately at the time of birth. Many unconditioned reflexes, for example, those associated with locomotion, sexual intercourse, occur in humans and animals a long time after birth, but they necessarily appear under the condition of normal development of the nervous system.

The whole set of unconditional and conditioned reflexes formed on their basis is usually divided into a number of groups according to their functional significance.

1. According to the receptor
   1. Exteroceptive reflexes
      • visual
      • olfactory
      • taste, etc.
   2. Interoreceptive reflexes- reflexes, in which the conditioned stimulus is irritation of the receptors of internal organs by a change in the chemical composition, temperature of internal organs, pressure in hollow organs and vessels
2. According to effector, i.e. by those effectors that respond to stimulation
   1. autonomic reflexes
      • food
      • cardiovascular
      • respiratory, etc.
   2. somato-motor reflexes- manifested in the movements of the whole organism or its individual parts in response to the action of the stimulus
      • defensive
3. By biological significance
   1. food
      • reflex act of swallowing
      • reflex act of chewing
      • reflex act of sucking
      • reflex act of salivation
      • reflex act of secretion of gastric and pancreatic juice, etc.
   2. defensive- elimination reactions from damaging and painful stimuli
   3. Sexual- reflexes associated with the implementation of sexual intercourse; the so-called parental reflexes associated with feeding and rearing offspring can also be included in this group.
   4. Stato-kinetic and locomotor- reflex reactions to maintain a certain position and movement of the body in space.
   5. Reflexes of maintaining homeostasis
      • thermoregulation reflex
      • respiratory reflex
      • cardiac reflex
      • vascular reflexes that contribute to maintaining the constancy of blood pressure, etc.
   6. Orienting reflex- a reflex to novelty. It arises in response to any fairly rapidly occurring fluctuation of 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 light stimulus that has appeared, etc. The implementation of this reflex provides the best perception of the acting agent and has an important adaptive value.

      IP Pavlov figuratively called the orienting reaction the reflex "what is it?" This reaction is innate and does not disappear with the complete removal of the cerebral cortex in animals; it is also observed in children with underdeveloped cerebral hemispheres - anencephaly.

The difference between the orienting reflex and other unconditional reflex reactions is that it fades relatively quickly with repeated applications of the same stimulus. This feature of the orienting reflex depends on the influence of the cerebral cortex on it.

The above classification of reflex reactions is very close to the classification of various instincts, which are also divided into food, sexual, parental, defensive. This is understandable due to the fact that, according to IP Pavlov, instincts are complex unconditioned reflexes. Their distinguishing features are the chain nature of reactions (the end of one reflex serves as the causative agent of the next) and their dependence on hormonal and metabolic factors. Thus, the emergence of sexual and parental instincts is associated with cyclic changes in the functioning of the gonads, and the food instinct depends on those metabolic changes that develop in the absence of food. One of the features of instinctive reactions is also that they are characterized by many properties of the dominant.

The reflex component is a reaction to irritation (movement, secretion, change in breathing, etc.).

Most unconditioned reflexes are complex reactions, which include several components. So, for example, with an unconditioned defensive reflex caused in a dog by strong electrical stimulation of the limb, along with protective movements, breathing intensifies and quickens, cardiac activity accelerates, voice reactions appear (screeching, barking), the blood system changes (leukocytosis, platelets and etc.). In the food reflex, its motor (grasping, chewing, swallowing), secretory, respiratory, cardiovascular and other components are also distinguished.

Conditioned reflexes, as a rule, reproduce the structure of the unconditioned reflex, since the conditioned stimulus excites the same nerve centers as the unconditioned one. Therefore, the composition of the components of the conditioned reflex is similar to the composition of the components of the unconditioned reaction.

Among the components of the conditioned reflex, the main reflexes specific to this type and secondary components are distinguished. In the defensive reflex, the motor component is the main one, in the food reflex, the motor and secretory ones.

Changes in respiration, cardiac activity, and vascular tone accompanying the main components are also important for the integral response of the animal to a stimulus, but, as IP Pavlov said, they play a "purely auxiliary role." Thus, increased and increased respiration, increased heart rate, increased vascular tone, caused by a conditioned defensive stimulus, contribute to an increase in metabolic processes in the skeletal muscles and thereby create optimal conditions for the implementation of protective motor reactions.

In the study of conditioned reflexes, the experimenter often chooses any one of its main components as an indicator. Therefore, they speak of conditioned and unconditioned motor or secretory or vasomotor reflexes. However, it must be taken into account that they are only separate components of the integral reaction of the organism.

The biological significance of conditioned reflexes lies in the fact that they make it possible to adapt much better and more accurately to the conditions of existence and survive in these conditions.

As a result of the formation of conditioned reflexes, the body reacts not only directly to unconditioned stimuli, but also to the possibility of their action on it; reactions appear some time before unconditional irritation. This very organism turns out to be prepared in advance for the actions that it has to carry out in a given situation. Conditioned reflexes help to find food, avoid danger in advance, eliminate harmful influences, etc.

The adaptive significance of conditioned reflexes is also manifested in the fact that the precedence of a conditioned stimulus to an unconditioned one strengthens the unconditioned reflex and accelerates its development.

The behavior of animals is different forms of external, mainly motor activity, aimed at establishing vital connections between the organism and the environment. Animal behavior consists of conditioned, unconditioned reflexes and instincts. Instincts include complex unconditioned reactions that, being innate, appear only at certain periods of life (for example, the instinct of nesting or feeding offspring). Instincts play a leading role in the behavior of lower animals. However, the higher an animal is at the evolutionary level, the more complex and diverse its behavior, the more perfect and subtle it adapts to the environment, and the greater the role of conditioned reflexes in its behavior.

The environment in which animals exist is very variable. Adaptation to the conditions of this environment by means of conditioned reflexes will be subtle and precise only if these reflexes are also changeable, i.e., conditioned reflexes that are unnecessary in new environmental conditions disappear, and new ones are formed in their place. The disappearance of conditioned reflexes occurs due to the processes of inhibition.

Distinguish between external (unconditioned) inhibition of conditioned reflexes and internal (conditioned) inhibition.

External inhibition of conditioned reflexes arises under the influence of extraneous stimuli that cause a new reflex reaction. This inhibition is called external because it develops as a result of processes occurring in areas of the cortex that are not involved in the implementation of this conditioned reflex.

Superstrong or long-acting extraneous stimuli can cause prohibitive inhibition of reflexes.

Internal inhibition of conditioned reflexes occurs in the absence of reinforcement by an unconditioned stimulus of the received signal.

In this case, internal inhibition does not appear immediately. As a rule, repeated application of an unreinforced signal is required.

The fact that this is inhibition of the conditioned reflex, and not its destruction, is evidenced by the restoration of the reflex the next day, when the inhibition has passed. Various diseases, overwork, overstrain causes a weakening of internal inhibition.

If the conditioned reflex is extinguished (not reinforced with food) for several days in a row, then it may disappear altogether.

There are several types of internal inhibition. The form of inhibition considered above is called extinctive inhibition. This inhibition underlies the disappearance of unnecessary conditioned reflexes.

Another variety is differentiated (distinctive) inhibition.

An unreinforced conditioned stimulus causes inhibition in the cortex and is called an inhibitory stimulus. With the help of the described technique, it was possible to determine the distinctive ability of different sense organs in animals.

The phenomenon of disinhibition. It is known that extraneous stimuli cause inhibition of conditioned reflexes. If an extraneous stimulus occurs during the action of an inhibitory stimulus, for example, when a metronome is used at a frequency of 100 times per minute, as in the previous case, then this will cause the opposite reaction - saliva will flow. IP Pavlov called this phenomenon disinhibition and explained it by the fact that an extraneous stimulus, causing an orienting reflex, inhibits any other process that is currently taking place in the centers of the conditioned reflex. If the inhibition process is inhibited, then all this leads to the excitation and implementation of a conditioned reflex.

The phenomenon of disinhibition also indicates the inhibitory nature of the processes of discrimination and extinction of conditioned reflexes.

The value of conditional inhibition very large. Thanks to inhibition, a much better correspondence of the reaction of the organism to external conditions is achieved, and its adaptation to the environment is more perfect. The combination of two forms of a single nervous process - excitation and inhibition - and their interaction enable the body to orient itself in various complex situations, are the conditions for the analysis and synthesis of stimuli.

In the body of an animal there is a continuous metabolism, as a result of which there is a need for food, water, etc. The need that has arisen causes purposeful behavior to satisfy it.

Feelings of fear, cold, or other causes also cause the animal to react in a certain way to environmental stimuli. All of these reactions are innate. They are inherited and appear in every animal. Such persistently inherited innate responses of the organism to stimuli of the internal and external environment are called unconditioned reflexes.

Congenital unconditioned reflexes can be simple (constriction or dilation of the pupils under the influence of light, withdrawal of the paw when pricked, blinking reflex) and more complex. More complex reflexes are called instincts.

All instincts are divided into two main groups:

1) self-preservation instincts: food, defensive, orienting, imitation, herd, cleanliness, reflex struggle with restrictions (freedom reflex), goal reflex, game instinct, etc .;

2) instincts aimed at preserving the race; sexual, parental.

Let's take a closer look at some of these instincts.

The goal reflex is expressed in the fact that if a motor act has begun, then its completion is required. The dog tries to master the irritating object. This reflex is based on the development of the dog's grip. Or some other phenomenon. Dog lovers know how a dog resists the first time they try to muzzle it. This is the fight against restrictions - a manifestation of the reflex of freedom. The orienting reflex, which occurs to any change in the environment, to each new stimulus (sound, olfactory, etc.), is expressed in the movement of the eyes, the rotation of the auricles, head, and sometimes the entire body in the direction of the stimulus, as well as in listening, in sniffing, examining this stimulus. Depending on the nature of the stimulus, the orienting reflex can then be replaced by a defensive, food, game or other, and also, unlike other unconditioned reflexes, it can fade away with repeated action of a stimulus that is not important for the body.

Unlike simple unconditioned reflexes, complex unconditioned reflexes consist of a whole chain of simple ones. In a complex unconditioned reflex, the action of one reflex is a stimulus for another. For example, a bitch's concern for puppies manifests itself in a number of actions: she gnaws the umbilical cord at birth, licks the puppies, feeds them, warms them and protects them.

Thanks to instincts , formed by thousands of previous generations, newborn animals from the very birth are able to respond to certain environmental influences with the same expedient behavior as their parents. But not all instincts are manifested in animals in the very first minutes of their life and do not remain for life. A dog suffering from helminths (worms) begins to eat Chernobyl, which he usually does not touch - here the expedient inherited reaction makes itself felt only under specific conditions, regardless of the age of the animal. It may not appear if it is not needed. With age, the sexual instinct manifests itself in dogs; with the aging of the body, it disappears.
The degree and forms of manifestation of instincts depend not only on the physiological state of the organism, but also on the influence of the environment. As a result, the manifestation of instincts in an adult dog is always complicated by acquired experience. It suffices to compare the behavior of a newborn, aimed at finding food, and an adult animal. The search for the newborn is not certain, and the adult animal immediately rushes to the place where it has repeatedly satisfied this need.

Parents play an important role in the acquisition of skills by young animals. Parents teach their offspring to distinguish stimuli in a huge variety of environments that contribute to or, conversely, hinder the satisfaction of basic, vital needs. In the future, each animal replenishes its experience independently. Depending on the conditions of life, it develops many conditioned reflexes that help it more successfully satisfy its needs.
In dog training, the so-called complex unconditioned position reflexes are of great importance. These reflexes are usually understood as the actions of the dog, through which it assumes a certain position, for example, sits down, lies down, jumps.

Instinct- this is the adaptation of animals to strictly defined environmental conditions. Therefore, if conditions change, the animal, in order to adapt to them, needs to supplement instincts, make adjustments to behavior. In this regard, animals have developed the ability to learn, to use "personal" experience in behavior. This ability is based on a conditioned reflex, thanks to which training is possible.

Higher nervous activity (HNI)

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

GNI is based on complex electrical and chemical processes occurring in the cells of the cerebral cortex of the cerebral hemispheres. Receiving information through the sense organs, the brain ensures the interaction of the body with the environment and maintains the constancy of the internal environment in the body.

The study of higher nervous activity is based on the works of I.M. Sechenov - "Reflexes of the brain", I.P. Pavlova (the theory of conditioned and unconditioned reflexes), P.K. Anokhin (the theory of functional systems) and numerous other works.

Features of higher nervous activity of a person:

• developed mental activity;
• speech;
• ability to abstract-logical thinking.

The foundation for the creation of the doctrine of higher nervous activity was laid by the works of the great Russian scientists I.M. Sechenov and I.P. Pavlova.

Ivan Mikhailovich Sechenov in his book "Reflexes of the Brain" proved that a reflex is a universal form of interaction between the body and the environment, that is, not only involuntary, but also voluntary, conscious movements have a reflex character. They begin with irritation of any sense organs and continue in the brain in the form of certain neural phenomena, leading to the launch of behavioral reactions.

A reflex is a response of the body to irritation that occurs with the participation of the nervous system.

THEM. Sechenov argued that the reflexes of the brain include three links:

• The first, initial link is the excitation in the sense organs 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, that is, 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 that people get from their ancestors, and acquired ones that arise during life, being the result of training. The assumptions and conclusions of I. M. Sechenov were ahead of their time.

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

All reflexes that occur in the body, Ivan Petrovich Pavlov divided into unconditioned and conditional.

Unconditioned reflexes

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

In unconditioned reflexes permanent reflex arcs that pass through the brain stem or through the spinal cord (for their implementation optional participation of the cortexcerebral hemispheres).

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

• food: separation of digestive juices in response to irritation of the receptors of the oral cavity, swallowing, sucking movements in a newborn.
• defensive: withdrawal of a hand that touched a hot object or with painful irritation, coughing, sneezing, blinking, etc.
• Sexual: the process of reproduction is associated with sexual reflexes.
• indicative(I.P. Pavlov called it the “what is it?” reflex) provides the perception of an unfamiliar stimulus. The orienting reflex appears in response to a new stimulus: a person is alert, listens, turns his head, squints his eyes, thinks.

Thanks to unconditioned reflexes, the integrity of the organism is preserved, the constancy of its internal environment is maintained, and reproduction occurs.

A complex chain of unconditioned reflexes is called instinct.

Example:

A mother feeds and protects her child, birds build nests - these are examples of instincts.

Conditioned reflexes

Along with hereditary (unconditional) there are reflexes that are acquired by each person throughout life. Such reflexes individual, and certain conditions are necessary for their formation, so they were called conditional.

A reflex is the body's response to an internal or external stimulus, carried out and controlled by the central nervous system. Our compatriots I.P. Pavlov and I.M. Sechenov.

What are unconditioned reflexes?

An unconditioned reflex is an innate stereotyped reaction of the body to the influence of the internal or environment, inherited from the offspring from the parents. It remains with 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 changes in the environment 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, an automatic response to a stimulus. And since a person is influenced by various factors, then the reflexes are different: food, defensive, indicative, sexual ... Salivation, swallowing and sucking belong to food. Defensive are coughing, blinking, sneezing, withdrawal of limbs from hot objects. Orienting reactions can be called turns of the head, squinting of the eyes. Sexual instincts include reproduction, as well as caring for offspring. The value of the unconditioned reflex lies in the fact that it ensures the preservation of the integrity of the body, maintains the constancy of the internal environment. Thanks to him, reproduction occurs. Even in newborns, an elementary unconditioned reflex can be observed - this is sucking. By the way, it is the most important. The irritant in this case is the touch to the lips of an object (nipples, mother's breasts, toys or fingers). Another important unconditioned reflex is blinking, which occurs when a foreign body approaches the eye or touches the cornea. This reaction refers to the protective or defensive group. It is also observed in children, for example, when exposed to strong light. However, the signs of unconditioned reflexes are most pronounced in various animals.

What are conditioned reflexes?

Reflexes acquired by the body during life are called conditioned reflexes. They are formed on the basis of inherited ones, subject to the influence of an external stimulus (time, knock, light, and so on). A vivid example is the experiments carried out 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 technique for obtaining them. So, to develop such reactions, it is necessary to have a regular stimulus - a signal. It starts the mechanism, and repeated repetition of the stimulus effect allows you 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 is awakening under the action of fundamentally new signals of an external nature. These stimuli of the surrounding world, to which the body was previously indifferent, begin to acquire exceptional, vital importance. Each living being can develop many different conditioned reflexes during his life, which form the basis of his experience. However, this applies only to this particular individual; this life experience will not be inherited.

An independent category of conditioned reflexes

In an independent category, it is customary to single out conditioned reflexes of a motor nature developed during life, that is, skills or automated actions. Their meaning lies in the development of new skills, as well as the development of 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 automatism and have become a reality of everyday life. The most successful way of mastering the skills is the systematic implementation of the exercise, the timely correction of the noticed mistakes, as well as the knowledge of the ultimate goal of any task. In the event that the conditioned stimulus is not reinforced for some time by the unconditioned stimulus, its inhibition occurs. However, it does not completely disappear. If, after some time, the action is repeated, the reflex will quickly recover. Inhibition can also occur under the condition of the appearance of an irritant of even greater force.

Compare unconditioned and conditioned reflexes

As mentioned above, these reactions differ in the nature of their occurrence and have a different formation mechanism. In order to understand what the difference is, just compare unconditioned and conditioned reflexes. So, the first are present in a living being from birth, during the whole life they do not change and do not disappear. In addition, unconditioned reflexes are the same in all organisms of a particular species. Their meaning is to prepare the living being for constant conditions. The reflex arc of such a reaction passes through the brain stem or spinal cord. As an example, here are some (congenital): active salivation when a lemon enters the mouth; sucking movement of the newborn; coughing, sneezing, pulling hands away from a hot object. Now consider the characteristics of conditioned reactions. They are acquired throughout life, can change or disappear, and, no less important, they are individual (their own) for each organism. Their main function is the adaptation of a living being 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.

Scheme of the unconditioned reflex

According to the research of academician I.P. Pavlov, the general scheme of unconditioned reflexes is as follows. Certain receptor nervous devices are affected by certain stimuli of the internal or external world of the organism. As a result, the resulting irritation transforms the entire process into the so-called phenomenon of nervous excitation. It is transmitted through nerve fibers (as 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 this part of the body. It turns out that these or those irritants are naturally connected with this or that activity in the same way as the cause with the effect.

Features of unconditioned reflexes

The characteristic of unconditioned reflexes presented below, as it were, systematizes the material presented above, it will help to finally understand the phenomenon we are considering. So, what are the features of inherited reactions?

Unconditional instinct and animal reflex

The exceptional constancy of the nervous connection underlying the unconditional instinct is explained by the fact that all animals are born with a nervous system. She is already able to respond properly to specific environmental stimuli. For example, a creature might flinch at a harsh sound; he will secrete digestive juice and saliva when food enters the mouth or stomach; it will blink with visual stimulation, 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.

The unconditioned reflex, in fact, is not a completely monotonous, stereotyped, transfer reaction of an animal to an external stimulus. It is characterized, though elementary, primitive, but still by variability, variability, depending on external conditions (strength, peculiarities of the situation, position of the stimulus). In addition, it is also influenced by the internal states of the animal (reduced or increased activity, posture, and others). So, even I.M. Sechenov in his experiments with decapitated (spinal) frogs showed that when the toes of the hind legs of this amphibian are acted upon, 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 adaptation of the animal to new or dramatically changing conditions.

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

Species specificity

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

Unconditional braking

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 able to cause a corresponding reaction - a reflex. If all of them could be realized, then the vital 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 inhibition of unconditioned reflexes occurs in the body. This means that the most important reflex at a particular moment of time delays the secondary ones. Usually, external inhibition can occur at the time of the start of another activity. The new exciter, 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 visitor. There is an abrupt change in activity, and the dog's salivation stops at that moment. Certain innate reactions are also referred to as unconditional inhibition of reflexes. In them, certain pathogens cause a complete cessation of some actions. For example, the anxious clucking of a chicken causes the chickens to freeze and cling to the ground, and the onset of darkness forces the kenar to stop singing.

In addition, there is also a protective id that arises as a response to a very strong stimulus that requires actions from the body that exceed its capabilities. The level of such exposure is determined by the frequency of impulses of the nervous system. The stronger the neuron is excited, the higher the frequency of the flow of nerve impulses that it generates will be. However, if this flow exceeds certain limits, then a process will occur that will begin to prevent the passage of excitation through the neural circuit. The flow of impulses along the reflex arc of the spinal cord and brain is interrupted, as a result, inhibition occurs, which preserves the executive organs from complete exhaustion. What follows from this? Thanks to the inhibition of unconditioned reflexes, the body selects from all possible options the most adequate one, able to protect against excessive activity. This process also contributes to the manifestation of the so-called biological caution.

Our nervous system is a complex mechanism for the interaction of neurons that send impulses to the brain, and it, in turn, controls all organs and ensures their work. This process of interaction is possible due to the presence in a person of the main inseparable acquired and innate forms of adaptation - conditional and unconditional reactions. A reflex is a conscious response of the body to certain conditions or stimuli. Such well-coordinated work of nerve endings helps us interact with the outside world. A person is born with a set of simple skills - this is called An example of such behavior: the ability of an infant to suck on its mother's breast, swallow food, blink.

and animal

As soon as a living being is born, he needs certain skills that will help ensure his life. The body actively adapts to the surrounding world, that is, it develops a whole range of purposeful motor skills. This mechanism is called species behavior. Each living organism has its own set of reactions and innate reflexes, which is inherited and does not change throughout life. But the behavior itself is distinguished by the method of its implementation and application in life: congenital and acquired forms.

Unconditioned reflexes

Scientists say that an innate form of behavior is an unconditioned reflex. An example of such manifestations has been observed since the birth of a person: sneezing, coughing, swallowing saliva, blinking. The transfer of such information is carried out by inheritance of the parent program by centers that are responsible for reactions to stimuli. These centers are located in the brain stem or spinal cord. Unconditioned reflexes help a person quickly and accurately respond to changes in the external environment and homeostasis. Such reactions have a clear demarcation depending on biological needs.

• Food.
• Approximate.
• Protective.
• Sexual.

Depending on the species, living beings have different reactions to the world around them, but all mammals, including humans, have a sucking skill. If you attach an infant or a young animal to the mother's nipple, a reaction will immediately occur in the brain and the feeding process will begin. This is the unconditioned reflex. Examples of eating behavior are inherited in all creatures that receive nutrients from mother's milk.

Defense reactions

These types of reactions to external stimuli are inherited and are called natural instincts. Evolution has laid in us the need to protect ourselves and take care of our safety in order to survive. Therefore, we have learned to instinctively respond to danger, this is an unconditioned reflex. Example: Have you noticed how the head deviates if someone raises a fist over it? When you touch a hot surface, your hand withdraws. This behavior is also called hardly a person in their right mind will try to jump from a height or eat unfamiliar berries in the forest. The brain immediately starts the process of processing information that will make it clear whether it is worth risking your life. And even if it seems to you that you don’t even think about it, the instinct immediately works.

Try to bring your finger to the baby's palm, and he will immediately try to grab it. Such reflexes have been developed over the centuries, however, now such a skill is not really needed by a child. Even among primitive people, the baby clung to the mother, and so she endured him. There are also unconscious innate reactions, which are explained by the connection of several groups of neurons. For example, if you hit the knee with a hammer, it will twitch - an example of a two-neuron reflex. In this case, two neurons come into contact and send a signal to the brain, causing it to respond to an external stimulus.

Delayed reactions

However, not all unconditioned reflexes appear immediately after birth. Some arise as needed. For example, a newborn baby practically does not know how to navigate in space, but after about a couple of weeks he begins to react to external stimuli - this is an unconditioned reflex. Example: the child begins to distinguish the voice of the mother, loud sounds, bright colors. All these factors attract his attention - an indicative skill begins to form. Involuntary attention is the starting point in the formation of the assessment of stimuli: the baby begins to understand that when the mother speaks to him and approaches him, most likely she will take him in her arms or feed him. That is, a person forms a complex form of behavior. His crying will draw attention to him, and he uses this reaction consciously.

sexual reflex

But this reflex belongs to the unconscious and unconditioned, it is aimed at procreation. It occurs during puberty, that is, only when the body is ready for procreation. Scientists say that this reflex is one of the strongest, it determines the complex behavior of a living organism and subsequently triggers the instinct to protect its offspring. Despite the fact that all these reactions are inherently human, they are launched in a certain order.

Conditioned reflexes

In addition to the instinctive reactions that we have at birth, a person needs many other skills in order to better adapt to the world around him. Acquired behavior is formed both in animals and in humans throughout life, this phenomenon is called "conditioned reflexes". Examples: at the sight of food, salivation occurs, while observing the diet, there is a feeling of hunger at a certain time of the day. Such a phenomenon is formed by a temporary connection between the center or vision) and the center of the unconditioned reflex. An external stimulus becomes a signal for a certain action. Visual images, sounds, smells are able to form stable connections and give rise to new reflexes. When someone sees a lemon, salivation may begin, and with a sharp smell or contemplation of an unpleasant picture, nausea occurs - these are examples of conditioned reflexes in humans. Note that these reactions can be individual for each living organism, temporary connections are formed in the cerebral cortex and send a signal when an external stimulus occurs.

Throughout life, conditioned responses can come and go. Everything depends on For example, in childhood, a child reacts to the sight of a bottle of milk, realizing that this is food. But when the baby grows up, this object will not form an image of food for him, he will react to a spoon and a plate.

Heredity

As we have already found out, unconditioned reflexes are inherited in every species of living beings. But conditional reactions affect only the complex behavior of a person, but are not transmitted to descendants. Each organism "adjusts" to a particular situation and the reality surrounding it. Examples of innate reflexes that do not disappear throughout life: eating, swallowing, reaction to the taste of the product. Conditioned stimuli change constantly depending on our preferences and age: in childhood, at the sight of a toy, the baby experiences joyful emotions; in the process of growing up, for example, visual images of a film evoke a reaction.

Animal reactions

Animals, like humans, have both unconditioned innate reactions and acquired reflexes throughout their lives. In addition to the instinct of self-preservation and the production of food, living beings also adapt to the environment. They develop a reaction to the nickname (pets), with repeated repetition, an attention reflex appears.

Numerous experiments have shown that it is possible to instill in a pet many reactions to external stimuli. For example, if at each feeding you call the dog with a bell or a certain signal, he will have a strong perception of the situation, and he will immediately react. In the process of training, rewarding a pet for an executed command with a favorite treat forms a conditioned reaction, walking a dog and the type of leash signals an imminent walk where he should relieve himself are examples of reflexes in animals.

Summary

The nervous system constantly sends a lot of signals to our brain, they form the behavior of humans and animals. The constant activity of neurons allows us to perform habitual actions and respond to external stimuli, helping to better adapt to the world around us.