Reflex is an example. Examples of congenital and acquired, conditioned and unconditioned reflexes in humans and animals

Reflexes are the main act of the nervous system. This is the body’s response to irritation of receptors, caused through the nervous system (see the article “Structure of the nervous system”).

The implementation of any reflexes involves: 1) an irritated group of receptors, or a receptive field, 2) afferent (receptive) neurons that transmit impulses from this receptive field to the nervous system, 3) interneurons that transmit impulses within the nervous system, 4) efferent neurons , transmitting impulses from the nervous system to the working organ, 5) afferent neurons, transmitting impulses from the receptors of the working organ about the nature and intensity of its activity, and 6) efferent neurons, transmitting impulses from the nervous system that regulate metabolism in the receptive field, receptors of the working organ and in specific cells of the working organ itself (sympathetic). Thus, the beginning of the reflex is irritation of the receptive field, then nerve impulses pass along the reflex ring until the efferent impulses stop entering the working organ.

Human and animal behavior

As soon as a living creature is born, it needs certain skills that will help ensure its life. The body actively adapts to the surrounding world, that is, it develops a whole complex of targeted motor skills. It is this mechanism that 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 behavior itself is distinguished by the method of its implementation and application in life: congenital and acquired forms.

Braking and its varieties

Braking has its own definition. The unconditional occurs under the influence of a fairly strong stimulus. Conditioned ones cease to act under the influence of a new stimulus.

Braking may be temporary. It occurs when the body is affected by several factors simultaneously. Conditioned inhibition should be developed. It can be divided into the following categories:

• Delayed.
• Conditional.
• Differentiation.
• Fading.

In the life of a living organism, inhibition is a necessary process. If it were not there, then quite a lot of reactions would arise, from which there was no benefit.

Unconditioned reflexes

Scientists say that the innate form of behavior is an unconditioned reflex. An example of such manifestations is observed from the moment a person is born: sneezing, coughing, swallowing saliva, blinking. The transfer of such information is carried out by inheriting the parent program by the centers of reflex arcs, which are responsible for reactions to stimuli. These centers are located in the brain stem or spinal cord. Unconditioned reflexes help a person to 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 creatures have different reactions to the world around them, but all mammals, including humans, have the habit of sucking. If you put a baby or young animal on the mother's nipple, a reaction will immediately occur in the brain and the feeding process will begin. This is an unconditioned reflex. Examples of feeding behavior are inherited in all creatures that receive nutrients from their mother's milk.

Reflex arc

It takes us about 500 milliseconds to respond to an event with a basic decision. If a decision does not need to be made, we can react in 100-200 milliseconds. At the same time, some reflexes work tens of times faster, and this is only possible due to the fact that thinking is not involved in this process.

A reflex is a reaction to an external influence that occurs without involving the cerebral cortex in this process (the nerve impulse passes through the spinal cord or stem). The path that the impulse travels is called a reflex arc. For example, if a person withdraws his hand from a burning object, the reflex arc includes the following elements:

• receptor (nerve endings in the finger that generate an impulse);
• afferent link (sensory neuron going to the spinal cord);
• the nerve center that determines the response (a small complex of neurons in the spinal cord);
• efferent link (motor neuron transmitting a signal to the muscle);
• effector (muscle that withdraws the hand).

The reflex arc provides an emergency response to a dangerous impact even before the person realizes that he has been burned. Because this reaction is not meaningful, in some cases it can lead to an undesirable result (for example, by withdrawing a hand, a person may push someone, lose balance, or get hurt).

Defensive reactions

These types of reactions to external stimuli are inherited and are called natural instincts. Evolution has given us the need to protect ourselves and take care of our safety in order to survive. Therefore, we have learned to instinctively react to danger; this is an unconditioned reflex. Example: Have you ever noticed how your head tilts when someone raises a fist over it? When you touch a hot surface, your hand jerks back. This behavior is also called the instinct of self-preservation: it is unlikely that a person in his right mind would 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 are not thinking about it, instinct immediately kicks in.

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

Causes of reflex dysfunction

All automatisms are unique. If the sucking or searching reflex may not appear only because the baby is not hungry at that moment, then spinal reactions should be checked regardless of the child’s mood or condition.

The cause of weakened reflexes may be:

• Difficult childbirth, injuries;
• Oxygen starvation during pregnancy or childbirth;
• Disorders of the central nervous system;
• Cerebral palsy;
• Lack of oxygen in muscle tissue;
• Spinal cord injuries;
• Use of medications that affect the nervous system;
• Paresis.

Weak reactions are observed in babies born prematurely. If reflexes are completely absent, then this is a reason to sound the alarm and consult a doctor.

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 respond to external stimuli - this is an unconditioned reflex. Example: a child begins to distinguish the mother’s voice, loud sounds, bright colors. All these factors attract his attention - an orientation skill begins to form. Involuntary attention is the starting point in the formation of an assessment of stimuli: the baby begins to understand that when the mother speaks to him and approaches him, most likely she will pick him up or feed him. That is, a person forms a complex form of behavior. His crying will attract attention to him, and he consciously uses this reaction.

Basic conditioned and unconditioned congenital reflexes in children - self-test

Reactions in a baby's life

The period of adaptation of the baby’s body to new conditions after intrauterine conditions lasts up to twenty-eight days. During this month, the child is helpless, the form of behavior has not yet been formed, he learns everything, is afraid of our wide space.

A little man is born, and certain reactions are transferred to him at the genetic level, which are called innate or unconditioned reflexes.

Reflexes tend to appear and disappear - this is considered normal. There is also a distinction between symmetry and asymmetry of responses. In a normally developing baby, the response should be the same on both the left and right sides of the body. A deviation is considered to be the absence of a reaction on one side.

It is also considered normal when the reflex strengthens and weakens over time. It is considered pathological if dullness or its absence is observed. In this case, they talk about a malfunction of the central nervous system or muscle tone.

As the baby’s brain improves and grows, conditioned (acquired) reactions are modeled.

The vital importance of innate reflexes in a newborn baby

Neonatologists identify about 15 vitally important unconditioned (innate) reflex reactions in a newborn baby. Moreover, some of them help the baby in the difficult process of birth. When they perform their function, they disappear. Another part is a kind of soil for the development of new ones. And the rest of the reactions play an important role in the formation of the child’s individuality.

Pediatric doctors distinguish 3 functional groups of unconditioned reflexes:

1. To ensure the fullness of vital functions: respiratory, sucking, swallowing, spinal;
2. Protects against environmental factors: cold, heat, bright light, wind and others;
3. “For a while”: one of these, like holding your breath at birth.

Unconditioned innate reflexes in children

In other words, oral “mouth” reactions. There are 9 subtypes of oral reactions:

• sucking
• swallowing
• proboscis
• palmo-oral (Babkina)
• search (Kussmaul)
• spinal
• upper protective
• respiratory
• gag reflex

Sucking

The baby makes active sucking movements as soon as he was born, when his mother put him to the breast; or when they give a bottle with a mixture or a pacifier.

Swallowing

Ability to swallow. Reaction with a person all his life.

Proboscis

When you lightly touch the baby's lips, the orbicularis muscle of the mouth contracts, which provokes the lips to curl into a tube, reminiscent of a baby elephant's trunk. Closer to three months, this skill fades away.

Palm-oral (Babkina)

By pressing with your thumbs on both palms of the baby, the reflex reaction of opening the mouth and bending the baby's head is triggered. Closer to the fourth month, the response fades away.

Search (Kussmaul)

Searching for mother's breasts. Touching the edges of the corners of the mouth, the child turns his head towards the object of irritation. The baby’s lower lip drops, and he receives the signal “it’s time to eat.” The reaction weakens in the first weeks of life, and completely disappears closer to a year.

Spinal

Spinal reactions are responsible for the formation and condition of the child’s muscular system. They help pediatricians determine how the baby is developing in the first year of life.

Upper protective

This means a reaction to protect the upper respiratory tract from possible respiratory dysfunction. It works immediately after birth and disappears in the first month.

Respiratory

The ability to breathe. A vital reaction for a person.

Gag reflex

From the category of “defensive reflexes”. The child pushes out solid food or objects with his tongue. The response works for a person throughout his life, but the stimulus (tongue) is involved only for some time, the first six months.

Grasp reflexes

Phylogenetically an unusually ancient reflex. When stroking his palm, the baby will instinctively clench his fingers. We will see the same thing when we stroke the pad of the baby’s toes. There are 2 subspecies of grasping:

1. Janiszewski and Robinson reflex;
2. Babinski reflex

Palmar (Yaniszewski and Robinson)

When stroking the center of the palm, the child will automatically and involuntarily grab an object or close his hand. The child develops such strong muscles that he can support his body weight. When checking, one of the required ones. Closer to four months it weakens.

Plantar (Babinski)

By stroking the outer edge of the foot, the baby's toes will open like a fan, and the foot will shrink at the back. In a child, the reflex is activated up to two years of age.

Conditioned reflexes in a newborn baby

Moro reflex

Known as fright. There are two phases of fear:

• The first is when the baby moves his arms to the side and opens his fists;
• The second (initial) – when the baby presses his arms to his body and clasps his fists tightly

The child reacts to loud sounds, sudden lifting of his legs, blows, knocks, and more. It is considered normal if the reflex occurs unexpectedly. Closer to four months, the reaction weakens, and later only its individual components are observed.

Kernig reflex

The child's legs, bent at the knees, try to straighten them at the joints of the pelvis and hips and move them to the sides. Given the correct development of the baby, this is impossible to do. The Kernig reaction is checked when the baby is 4 months old.

Automatic gait reflex

Response of the baby's central nervous system to walking. To check, you need to lift the baby and tilt his body a little forward. If the child steps on the entire leg, then development is proceeding correctly. If your feet catch on your feet, or you walk on tiptoes without placing your entire foot on the ground, it is advisable to tell your doctor about it.

Bauer reflex (crawling)

We place the child on his tummy, bring his legs together and place his palm on him. The baby will try to push off from the palm, bending and unbending its legs, and will begin to crawl.

Support reflex

The baby is not yet ready to stand, he is not yet strong, but the support reaction is already working. We take it under the arms and lift it vertically. Holding it in weight, the child will automatically tighten his legs, and placing him on the surface, the baby will straighten his body and stand on half-bent legs and on a full foot. The support works until the baby is 1.5 months old.

Galant reflex

Spinal reflex response. The child, when running a finger along the spine, will arch his back. At the same time, the head and legs will lower.

Independent testing of reflexes in children

As the baby masters and develops, innate reflexes fade, and the child finds new ways to express his needs. Most of them disappear by the third month.

Curious parents can check their child’s answers themselves. But it is important not to forget that the outcome of the observation may not be entirely reliable. Exposure to, say, a child feeling hungry or tired will affect the test. Therefore, it will be more reliable when a doctor checks your reflexes.

And it is better for the mother to use them as games with her newborn baby, thereby developing the baby and communicating with him. In the first months of life, the baby develops very quickly and the mother may not always notice these changes. Closer to the fourth week, the movements of the arms and legs become less erratic.

When he hears the voice of his parents, he calms down for a moment, and then regains his playfulness. Psychologists call this phenomenon motor revival. With its help, children attract the attention of their parents.

Impaired reactions

There are a lot of reactions. The main ones that will help parents check the development of the baby are presented above. A child’s lack of response to a stimulus may indicate a disturbance in the functioning of the central nervous system. You should consult a neurologist for advice.

Reaction call deviations

There are times when the baby does not respond. It's connected with:

1. hypoxia of the baby’s central nervous system;
2. cerebral palsy;
3. intracranial injury;
4. muscle hypotonia;
5. spinal cord injuries;
6. taking medications that depress the baby’s nervous system;

If the baby has a weak desire to suck, this may indicate that the baby is simply not hungry. Let’s say, to stimulate grasping, when feeding, the mother just needs to put her finger in the baby’s hand.

In other cases, it is better to consult a doctor.

And the main thing to remember is that the little man’s body is very strong, and the recovery process is very fast. The baby will definitely grow up healthy!

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Sexual reflex

But this reflex is unconscious and unconditional, 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 initially characteristic of humans, they are triggered in a certain order.

A variety of unconditioned reflexes

Innate forms of behavior (unconditioned reflexes and instincts) were developed in the process of evolution as a result of adaptation to certain, relatively constant environmental conditions. They endow the individual with a set of behavioral programs, ready for use as soon as necessary. Their role in behavior predominates in the case of animals with a short life span (invertebrates). For example, the female road pompils (a type of solitary wasp) emerges from the pupa in the spring and lives only for a few weeks. During this time, she must have time to meet the male, catch the prey (spider), dig a hole, drag the spider into the hole, lay an egg, seal the hole - and so on several times. The wasp emerges from the pupa as an “adult” and is immediately ready to carry out its activities. This does not mean that the pompila is not capable of learning. For example, she can and should remember the location of her burrow, which requires the formation of an appropriate conditioned reflex.

In highly organized vertebrates the situation is different. For example, a wolf cub is born blind and completely helpless. Of course, at birth he has a number of unconditioned reflexes, but they are clearly not enough for a full life. As it grows, a process of intensive learning occurs, as a result of which the animal is ready for independent existence.

The science of ethology studies the life and behavior of an individual in its natural environment .

The most difficult task facing it is to describe the interaction of innate and acquired components of behavior. Indeed, during the course of life, additionally formed conditioned reflexes are superimposed on the instinctive activity of the animal, and since they differ in different individuals, the final manifestations of instincts, pursuing a common goal, can also differ in different representatives of the same species. For example, birds living in different areas may use different materials when building a nest. The leading role in the creation of ethology as an independent science belonged to the Austrian scientist K. Lorenz and the Dutch scientist N. Tinbergen.

The physiology of VND, for its part, studies the behavior of animals under strictly controlled laboratory conditions. Of course, this behavior is simpler than in a real natural environment. But it is precisely this simplification that allows us to analyze the mechanisms of brain activity, which otherwise may be masked by various random reactions.

The variety of unconditioned reflexes also implies a variety of ways to divide them into types. As an example, we give the classification that was proposed by Academician P.V. Simonov. It quite fully takes into account all the main variants of innate behavior (Table 4.1).

Simonov proposed to distinguish three groups of unconditioned reflexes: vital (lat. vita -

life), zoosocial and self-development, differing in the characteristics of interaction with the environment and other individuals of their species.
Vital
reflexes can be defined as aimed at preserving the very life of the individual.
They meet two conditions: firstly, failure to perform one or another reflex from this group leads to the death of the individual; secondly, the implementation of the vital reflex does not require the participation of another individual of the same species. Zoosocial
(role) reflexes include those variants of innate behavior that arise when interacting with other individuals of their own species
. reflexes are the most difficult to determine .
Simonov proposes to include in this group reactions that are not related to adaptation to the current situation, but are, as it were, “facing the future.” If you observe the implementation of such a reflex, it often looks like a meaningless behavioral act. However, this is not the case, and the reaction that occurs has a biological significance that becomes apparent after some time.

Let us consider in more detail the listed groups of unconditioned reflexes.

The most studied variant of vital innate reactions are food

and
drinking
unconditioned reflexes. The stimuli that trigger them (as reinforcement) are food and water. In this case, it is possible to register a large number of reactions occurring at different levels of the central nervous system. The level of complexity of these reflexes also varies greatly, and at one pole there are the simplest autonomic and muscular reactions (salivation, chewing, swallowing), at the other - complex motor reflex complexes associated with pursuing and tracking prey, waiting in ambush, and the “deadly bite” reaction "in cats, storing food. Particularly interesting and complex forms of innate feeding behavior are exhibited by spiders that weave geometrically regular trapping networks from several types of webs. Weaving a web is an example of complex unconditioned reflex behavior. Thus, even a relatively small and seemingly uncomplicated nervous system can contain highly organized innate motor skills.

It can often be observed that not only taste signals are innately programmed as stimuli that trigger eating and drinking behavior, but also stimuli coming from other sensory systems: tactile (touching the lips causes a sucking reflex), visual (the chicken pecks at small objects), auditory (predator's reaction to rustling). Of particular importance is the assessment of the state of the internal environment of the body, and primarily the content of glucose and salts in the blood plasma, carried out by the neurons of the hypothalamus. A decrease in glucose concentration and an increase in NaCl content act as factors triggering eating and drinking behavior, causing the development of food and drinking motivations and are subjectively recognized by us as feelings of hunger and thirst.

The second group of vital unconditioned reactions are various types of defensive

behavior aimed primarily at stopping pain.
Pain is a special sensory modality that accompanies the action of various agents that damage body tissue. It is characterized by a particularly high level of significance, and the appearance of pain is often a signal to stop the individual’s current activity. There are two options for defensive behavior: passive-defensive
and
active-defensive reflexes.
The first are aimed at avoiding the source of pain by leaving the sphere of its action (reactions of fear, flight, concealment); the latter allow you to get rid of the source of pain by attacking it and actively eliminating the dangerous influence (aggression reaction). The simplest example of passive defensive reactions is the reflex of withdrawing a limb when burned; active-defensive reaction - an attempt to bite an object that causes pain.

Passive and active defensive reflexes are associated with different centers of the brain (posterior hypothalamus). Consequently, depending on the conditions, the same individual can experience both fear and aggression reactions. The former are more typical of herbivorous mammals; the latter arise relatively easily in predators. At the same time, even a harmless and weak creature, being deprived of the possibility of escape, is capable of offering serious resistance. Conversely, the most powerful and dangerous predators often prefer not to get involved in conflicts without any particular reason, choosing a passive defensive behavior.

Defensive reactions can be triggered not only by pain. They manifest themselves quite well with any strong and sudden sensory influences (shudder reactions, squinting), as well as with more specific stimuli, such as the appearance in the dark of two luminous dots - “eyes” or the movement of the silhouette of a bird of prey above the head (in both cases it is possible observe the hiding of newborn chicks (Fig. 4.8)). Defensive reactions can be included in more complex unconditioned reflex complexes. In this case, they often act as a stage of instinctive programs associated with sexual, territorial and other types of innate behavior.

An extremely important group of vital unconditioned reflexes are homeostatic

reactions of the nervous system.
The concept of homeostasis implies maintaining the constancy of the internal environment of the body, that is, maintaining a wide range of its physicochemical parameters at a stable level. This refers to a variety of autonomic and neuro-endocrine mechanisms. An example is a system for monitoring constant body temperature. This control is carried out due to the ability of a number of neurons in the hypothalamus to estimate blood temperature. When it decreases, the skin vasoconstriction reflex is triggered (saving heat) and small involuntary muscle contractions (trembling) are activated. If the blood temperature is higher than normal and the body is in danger of overheating, then sweating begins, peripheral vessels dilate and heat transfer increases. Our health ultimately depends on the quality of implementation of homeostatic reflexes, and their violation leads to psychosomatic disorders. Homeostatic reflexes include such vital reactions as the regulation of breathing, as well as the maintenance of circadian rhythms. In the latter case, we are talking about the whole sleep-wake
, which will be discussed in detail below.

Vital reflexes also include so-called grooming

and
saving reflex
.
The first of them consists of various reactions to care for one’s own body (licking, combing, and in birds, lubricating feathers). Grooming
is often observed in situations where the individual does not have more pressing needs, but without its periodic implementation, many organs would quickly fail.
The energy saving reflex
can be defined as follows: of the possible ways to achieve a goal, the animal chooses the easiest one, which requires the least amount of energy. The biological meaning of this reflex is obvious, since it allows you to reduce food consumption, which means that the individual is less exposed to the dangers associated with its search. This reflex can also be observed in an experiment: if a monkey is given the opportunity to receive food by turning a heavy or (at its choice) a light lever, the animal will clearly prefer the latter.

The most important among zoosocial reflexes is sexual

behavior observed at all levels of evolution. For its adequate implementation, two factors are necessary: ​​an appropriate hormonal background and certain, genetically determined triggering external stimuli. The hormonal background is created by the activity of the sex glands. In this case, the level of androgens in the blood is of key importance.

As is known, the vast majority of vertebrates are characterized by seasonal reproduction, which is associated with climatic rhythms, i.e., changes in environmental temperature and food availability. In such animals, a “burst” of sex hormones and sexual activity is observed only once or twice a year. The rest of the time they (at least the females) lose their ability to reproduce.

A number of mammal species (among them humans, rats, some monkeys) have acquired in the course of evolution the ability to reproduce year-round, which is associated with a gregarious way of life, in which the “social status” of a female capable of mating, as well as a pregnant or lactating female, is significantly higher than non-pregnant female. Of course, in this case, fluctuations in the level of sex hormones remain, but they are more smoothed out compared to the seasonal reproduction option.

Sensory stimuli that trigger sexual behavior can be very diverse. As a rule, first the male and female must identify each other at a considerable distance or the male must find the female. “Clues” are species-specific odors characteristic of mammals, moths, and beetles. In the case of many birds and fish, indicators of gender and factors in attracting individuals of the opposite sex are features of appearance (hence the bright coloring, especially during the breeding season). In birds, as well as in grasshoppers, cicadas, tailless amphibians and other “singers,” sound signals perform a similar function. In all these cases, sensory analysis (often requiring the recognition of very complex visual and auditory images) is an integral part of innate behavioral programs. It occurs without training on strictly determined networks of neurons that have a genetically predetermined structure and function.

When a male and a female meet, tactile stimuli come first, the purpose of which is to weaken possible manifestations of fear or aggression and prepare the transition to sexual behavior itself. This task is very important, since in many cases the male is significantly inferior in size to the female, and at the first moment she may consider him not only as a potential source of danger, but also as possible prey. The most famous example from this area is the mating relationship of spiders, as a result of which a significant part of the males die.

The difference in size between males and females is quite natural from an evolutionary point of view: compared to sperm, female reproductive cells should be significantly larger, since they carry a supply of nutrients for the development of the embryo; therefore, the female’s body must be larger than the male’s. In addition, the mother often carries the eggs and takes care of the nutrition of the cubs, which also implies larger sizes compared to the male. And only when males begin to take part in raising offspring, defending the nest territory, and obtaining food for the female and cubs, can an increase in their body size be observed.

Sexual behavior exhibits a wide range of relationships, from immediate mating to complex ritualized interactions (tournaments and courtship). Ethological analysis has shown that the first type of sexual behavior is usually observed in situations where the female is able to raise (and does raise) offspring without the help of a male (living conditions are relatively safe and food is abundant).

If the male performs his part of the parental functions, the female’s behavior turns out to be aimed at choosing the most suitable candidate. The selection criteria used are very diverse and are also components of innate behavioral programs. In tournament behavior, the key sign of the most “suitable” male is victory over rivals in some, usually ritualized battle. Ritualization here means that in the course of the evolution of sexual behavior, in most cases, methods of bloodless (and often non-contact) assessment of the strength of rivals arose. Specific examples can be found in the small but very interesting book by K. Lorenz “Aggression”. In particular, it describes the submissive poses adopted by the defeated male, which immediately stop the attack directed at him. The biological meaning of the tournaments is obvious - the largest and strongest males predominantly become the fathers of the cubs, which improves the genotype of the population as a whole. It is this process that has led to the fact that in most mammals, males are larger than females and effectively perform a protective function in relation to both the cubs and the females themselves.

Courtship behavior consists of the male demonstrating certain key stimuli (song; bright color and size of various body parts; built nest) or ritual motor reactions (dancing; movements similar to those of the cubs; play behavior; feeding the female). The male who receives the highest “score” usually enjoys the greatest success, and the score is “given” by the females based on innate criteria. Therefore, one can observe not only adaptively expedient, but also adaptively meaningless and even harmful results of sexual selection (for example, the development of a brightly colored and extremely long tail in male peacocks).

Let us briefly characterize other types of zoosocial unconditioned reflexes. In addition to sexual behavior, these include various options for child-parent

interactions. On the part of the parents (primarily the mother), this group of innate reactions includes the construction of a shelter-nest, feeding, cleaning, dragging the cubs, their protection, and later - play and punishment. In this case, the triggering effect is exerted by the appearance and smell of the cub, the sounds it makes, as well as complex changes in the hormonal status of the female, including those associated with the activity of the mammary glands. Thus, the innate reflex arc that ensures feeding is formed in mammals in such a way that the very fact of the mechanical impact of the baby on the nipples is perceived by the female’s brain (anterior zones of the hypothalamus) as reinforcement and causes positive emotions.

On the part of the cub, we can also observe a significant number of innate behavioral reactions triggered by various options for interaction with the female. These are suckling by the mother, the desire for physical contact with her, freezing reactions when carried, species-specific “calling cries” of the baby left alone, following reactions, etc. In parallel, one can observe the occurrence of various forms of learning, allowing the individual to normally realize various more “ subtle" variants of zoosocial behavior. Animals raised in isolation are characterized by disturbances in this behavior and are unable to interact normally with members of their own species.

Zoosocial behavior is not limited to the family. Its next option is the so-called territorial

behavior characteristic of the interaction of individuals in a population and consisting in dividing the habitat into separate hunting and nesting areas. The initial reason for the appearance of this behavior during evolution was the discrepancy between the resources of the territory where the population lives (lack of food, places for building nests) and the number of individuals in it. In other words, territorial unconditioned reflexes are a behavioral mechanism of protection against overpopulation, i.e., a situation when the risk of starvation, epidemics and other events harmful to the population increases sharply.

There is a wide variety of forms of territorial behavior - depending on how long, for what purposes and in what ways the division of “spheres of influence” occurs, and how it is subsequently maintained. In the simplest case, the site is occupied by the first individual that appears on it. The size of the plot is a genetically determined characteristic (determined by the need to obtain the required amount of food). In the future, one can observe various behavioral reactions associated with the protection of the territory: a direct attack on the “aggressor”, marking boundaries with the help of species-specific odors, vocal reactions (one of the functions of song in birds). A component of territorial behavior is also the reflexes of a “stranger” who finds himself in an already occupied area. They occur in the form of passive defensive reactions and postures of submission, followed by flight. If we are talking about the redistribution of territory or the struggle for a vacated area, then various options for intraspecific aggression are possible - from tournaments to inflicting injuries of varying degrees of severity. Often the division of territory occurs independently for males and females; their areas turn out to intersect, but the manifestation of territorial behavior is provoked only by a meeting with an individual of the same sex.

Innate reflexes associated with behavior

animal
in a pack
(community). This refers to hierarchically organized packs with a clear distinction of a leader and several levels of subordinates. Such packs should be distinguished from so-called homogeneous packs (without a leader) and family packs (usually temporary and very small). In hierarchical societies, the leader can be both a male (monkeys) and a female (hyenas, elephants). His interaction with his “subordinates” includes postures of dominance and submission, as well as intraspecific aggression of varying levels of intensity. Similar contacts can be observed on other steps of the school hierarchy, which is often independent for males and females. The desire to dominate “in one’s circle” is one of the most powerful innate human needs.

The third type of unconditioned reflexes is self-development reflexes, which are characterized as “directed to the future.” The easiest way to understand this definition is through the example of exploratory behavior,

during which the reinforcement is new information. At the moment the brain receives such information, it is not yet clear how it will be used (it will trigger eating, sexual or any other behavior) and whether it will be used at all. However, the collection of information when changes occur in the surrounding world necessarily occurs and is based on a number of unconditional reflex mechanisms.

In its simplest form, exploratory behavior manifests itself as an orienting reflex (in Pavlov’s terminology, the “what is this?” reflex). In this case, one can observe a characteristic set of movements that occurs when a new stimulus appears in the environment: turning the eyes, head, ears, and the whole body towards the signal source. The biological meaning of what is happening is to bring the senses to a position that ensures the most effective perception of new information. The orientation reflex in its clearest form is triggered by unexpected visual and auditory signals. The centers for triggering the orientation reflex are localized in the quadrigeminal region of the midbrain.

A more complex form of exploratory behavior is active search reflexes. A rat, a dog, a cat, or a person, having entered a new room, actively explore it in order to detect food, danger, etc. This exploration is accompanied by an inspection of the territory, approaches to potentially interesting objects, looking at them, sniffing them, and testing them out.

The most complex type of exploratory behavior is manipulation with objects, characteristic of primates. In this case, one can observe subtle movements of the fingers, with the help of which a monkey or a person feels an object, tries to break it or untwist it (destructive manipulations). At the same time, we receive a large amount of additional information regarding the possible use of this item in various types of activities.

Self-development reflexes also include the freedom reflex.

Its essence is to overcome restrictions on freedom of movement in space. It is for this reason that animals strive to break their leash, destroy the walls of their cage, and get out of the pit. The biological meaning of what is happening is obvious, since an individual deprived (or almost deprived) of the ability to move will very soon die from thirst and hunger or become a victim of predators. The term “freedom reflex” itself was introduced by Pavlov, who observed it in a sharply enhanced form in some dogs. Such animals became unsuitable for training using standard methods of developing conditioned reflexes (the latter including restraining the dog with belts). The freedom reflex was manifested in a very clear form in Thorndike’s experiments (“problem boxes”, “trial and error method”), as well as in the experiments of the Russian researcher V.P. Protopopov, when not an animal, but food was placed in a box.

Imitative

behavior is also one of the forms of manifestation of self-development reflexes. When an animal repeats someone else's reaction, the meaning of its activity is often unclear (since there is no real reinforcement), but the very principle of imitation as a method of non-genetic transfer of information from individual to individual has proven its usefulness and therefore has been consolidated during evolution. In the simplest case, imitation follows the “do as your neighbor” scheme. This kind of reaction is especially typical for homogeneous schools, when a turn of one fish, say, to the right will cause a turn of its neighbors. The biological meaning of what is happening is quite clear: the fish that turned first may have useful information that a nearby individual does not have.

Imitation according to the “do as a parent” scheme is of great importance. The desire of the baby to imitate the behavior of its mother and father is the innate basis on which a huge number of imitative conditioned reflexes are formed. The third option - “do as the leader” is typical for hierarchical packs. Having developed a conditioned reflex in the leader monkey to press the lever (to get food), you can then detect the same reaction in other members of the troop.

The last thing I would like to mention is the gaming

behavior. Watching a kitten chasing a bow or puppies wrestling, we may at first judge their behavior as meaningless. However, these and other similar reactions are, in fact, training of skills (including intraspecific communication skills) that the individual will need in adulthood. So here, too, “future orientation” as the most characteristic feature of self-development reflexes can be traced quite clearly. In the case of humans, gaming types of behavior include various forms of non-professional sports, as well as a variety of children's outdoor games.

Concluding our brief review of unconditioned reflexes, we once again emphasize that they are the basis on which the entire diversity of behavior “grows.” Having traced even the most complex acquired reactions, we can discover their innate foundation, which at one time was, as it were, a “source of energy” that made it possible to implement learning processes.

In the case of invertebrates, we see the most complex complexes of innate reflexes, honed over millions of years of evolution - instincts, which during the individual (usually very short) existence of the individual are only slightly supplemented by acquired reactions. In the case of highly developed vertebrates, the picture is significantly different, and their instinctive reactions in the course of individual development turn out to be very powerfully covered by conditioned reflex “layers”. At the same time, the level of adaptability of the behavior of each individual individual sharply increases, which allows it to exist and reproduce for a long time.

The process of forming acquired reactions in humans is especially complex. Therefore, the desire to identify the innate foundations of our behavior is inherent not only in physiologists, but also in psychologists. In the latter case, one can often observe noticeable “distortions” when one or another psychological theory postulates the primary importance, dominance of only one of the areas - sexual behavior (3. Freud), aggressive behavior and the desire for leadership “in the pack” (A. Adler) etc.

Conditioned reflexes

In addition to the instinctive reactions that we have at birth, a person needs many other skills to better adapt to the world around him. Acquired behavior is formed in both animals and people throughout life; this phenomenon is called “conditioned reflexes”. Examples: when you see food, salivation occurs; when you follow a diet, you feel hungry at a certain time of the day. This phenomenon is formed through a temporary connection between the center of the analyzer (smell or vision) and the center of the unconditioned reflex. An external stimulus becomes a signal for a specific action. Visual images, sounds, smells can form lasting connections and give rise to new reflexes. When someone sees a lemon, salivation may begin, and when a strong smell or contemplation of an unpleasant picture occurs, nausea may occur - 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 reactions can arise and also disappear. It all depends on the person's needs. For example, in childhood, a child reacts to the sight of a bottle of milk, realizing that it 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.

How do reflexes work?

The natural meaning of a reflex is that certain events or external influences on the body require a specific response. For example, severe fear in most animals causes a release of adrenaline, increased muscle tone, and increased heart rate and breathing. All this is necessary to increase the chances of successfully repelling an attack or escaping.

To better understand what a reflex is and how it differs from instinct, you need to know its 5 main features:

1. it is based on nervous excitement;
2. the reflex cannot be spontaneous;
3. there is always an irritant;
4. the transformation of sensory excitation into effector excitation occurs without the participation of higher nervous activity;
5. reflexes are necessary to quickly adapt to changing circumstances.

Instinct, unlike reflex, is not conditioned by anything. For example, fear is an instinctive feeling that ensures survival. Disgust is also an instinct designed to protect us from food poisoning or infection. The crying of a child, the desire to gather in groups, conforming behavior, the desire to dominate or occupy a higher position in the social hierarchy - these are all instincts.

The reflex can be triggered in response to a single stimulus or to a combination of several stimuli. For example, in the famous experiment of Academician Pavlov, a dog’s digestive process was activated in response to a bell. This is a reflex to a single stimulus.

This experiment can be complicated by developing a reflex that will work only in the presence of a certain combination or sequence of stimuli (for example, the simultaneous inclusion of sound and light or the sequential playback of several sounds).

Heredity

As we have already found out, unconditioned reflexes are inherited in every species of living beings. But conditioned reactions only affect complex human behavior, but are not passed on to descendants. Each organism “adapts” 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 a product. Conditioned stimuli change constantly depending on our preferences and age: in childhood, when a child sees a toy, he experiences joyful emotions; in the process of growing up, a reaction is caused, for example, by visual images of a film.

Unconditioned reflexes by month

All unconditioned reflexes appear immediately after birth, but the period of extinction is different for everyone. Some reflexes, such as breathing or swallowing, remain for life, others fade quite quickly. So that mom doesn’t have to memorize every skill, you can use the following table.

We have decided on what a newborn can do and what he can do. You also now know how to test certain reflexes. It remains to find out when automatisms may be weakened or absent altogether, and when it is worth sounding the alarm.

Animal reactions

Animals, like humans, have both unconditioned innate reactions and acquired reflexes throughout life. In addition to the instinct of self-preservation and obtaining food, living beings also adapt to their environment. They develop a reaction to the nickname (pets), and 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 you call your dog with a bell or a certain signal at each feeding, he will have a strong perception of the situation and he will immediately react. During the training process, rewarding a pet for following a command with a favorite treat forms a conditioned reaction; walking the dog and the sight of a leash signals an imminent walk, where he must relieve himself - examples of reflexes in animals.

Innate physiological reflexes are... What are Innate physiological reflexes?

The main unconditioned reflexes of a newborn and infant are divided into two groups: segmental motor automatisms, provided by segments of the brain stem (oral automatisms) and the spinal cord (spinal automatisms), and suprasegmental posotonic automatisms (centers of the medulla oblongata and midbrain).

Spinal motor automatisms

Newborn protective reflex

If a newborn is placed on his stomach, a reflexive turn of the head to the side occurs. This reflex is expressed from the first hours of life. In children with damage to the central nervous system, the protective reflex may be absent, and if the child's head is not passively turned to the side, he may suffocate. In children with cerebral palsy, with increased extensor tone, a prolonged raising of the head and even throwing it back is observed.

Support reflex and automatic gait of newborns

The newborn is not ready to stand, but he is capable of support reaction. If you hold a child vertically in weight, he bends his legs at all joints. The child, placed on a support, straightens his torso and stands on half-bent legs on a full foot. A positive support reaction of the lower extremities is a preparation for stepping movements. If the newborn is slightly tilted forward, he makes stepping movements (automatic gait of newborns). Sometimes when walking, newborns cross their legs at the level of the lower third of their legs and feet. This is caused by a stronger contraction of the adductors, which is physiological for this age and superficially resembles the gait of cerebral palsy.

The support reaction and automatic gait are physiological up to 1 - 1.5 months, then they are suppressed and physiological astasia-abasia develops. Only by the end of 1 year of life does the ability to stand and walk independently appear, which is considered as a conditioned reflex and for its implementation requires normal function of the cerebral cortex. In newborns with intracranial injury who were born with asphyxia, in the first weeks of life the support reaction and automatic gait are often depressed or absent. In hereditary neuromuscular diseases, the support reaction and automatic gait are absent due to severe muscle hypotonia. In children with damage to the central nervous system, automatic gait is delayed for a long time.

Crawling reflex (Bauer) and spontaneous crawling

The newborn is placed on his stomach (head in the midline). In this position, he makes crawling movements - spontaneous crawling. If you place your palm on the soles, the child reflexively pushes away from it with his feet and crawling intensifies. In the position on the side and on the back, these movements do not occur. There is no coordination of movements of the arms and legs. Crawling movements in newborns become pronounced on the 3rd - 4th day of life. The reflex is physiological until 4 months of life, then it fades away. Independent crawling is a precursor to future locomotor acts. The reflex is depressed or absent in children born with asphyxia, as well as with intracranial hemorrhages and spinal cord injuries. Attention should be paid to the asymmetry of the reflex. In diseases of the central nervous system, crawling movements persist for up to 6–12 months, like other unconditioned reflexes.

Grasp reflex

Appears in a newborn when pressure is applied to his palms. Sometimes the newborn clasps his fingers so tightly that he can be lifted up (Robinson reflex). This reflex is phylogenetically ancient. Newborn monkeys are held on the mother's hair by gripping their hands. With paresis of the hands, the reflex is weakened or absent, in inhibited children the reaction is weakened, in excitable children it is strengthened. The reflex is physiological until 3-4 months; later, on the basis of the grasping reflex, voluntary grasping of an object is gradually formed. The presence of a reflex after 4 - 5 months indicates damage to the nervous system.

The same grasping reflex can be evoked from the lower extremities. Pressing the ball of the foot with the thumb causes plantar flexion of the toes. If you apply a line irritation to the sole of the foot with your finger, then dorsiflexion of the foot and fan-shaped divergence of the toes occurs (Babinsky’s physiological reflex).

Galant reflex

When the skin of the back is irritated paravertebrally along the spine, the newborn bends his back, forming an arch open towards the irritant. The leg on the corresponding side is often extended at the hip and knee joints. This reflex is well evoked from the 5th - 6th day of life. In children with damage to the nervous system, it may be weakened or completely absent during the 1st month of life. When the spinal cord is damaged, the reflex is absent for a long time. The reflex is physiological until the 3rd - 4th month of life. If the nervous system is damaged, this reaction can be observed in the second half of the year and later.

Perez reflex

If you run your fingers, pressing lightly, along the spinous processes of the spine from the tailbone to the neck, the child screams, raises his head, straightens his torso, and bends his upper and lower limbs. This reflex causes a negative emotional reaction in the newborn. The reflex is physiological until the 3rd - 4th month of life. Suppression of the reflex during the neonatal period and a delay in its reverse development are observed in children with damage to the central nervous system.

Moro reflex

It is caused by various techniques: a blow to the surface on which the child is lying, at a distance of 15 cm from his head, raising the straightened legs and pelvis above the bed, sudden passive extension of the lower extremities. The newborn moves his arms to the sides and opens his fists - phase 1 of the Moro reflex. After a few seconds, the hands return to their original position - phase II of the Moro reflex. The reflex is expressed immediately after birth, it can be observed during the manipulations of the obstetrician. In children with intracranial trauma, the reflex may be absent in the first days of life. With hemiparesis, as well as with obstetric paresis of the arm, asymmetry of the Moro reflex is observed.

With severe hypertension, there is an incomplete Moro reflex: the newborn only slightly withdraws his arms. In each case, the threshold of the Moro reflex should be determined - low or high. In infants with damage to the central nervous system, the Moro reflex is delayed for a long time, has a low threshold, and often occurs spontaneously with anxiety or various manipulations. In healthy children, the reflex is well expressed until the 4th - 5th month, then it begins to fade; after the 5th month, only individual components can be observed

Oral segmental automatisms

Sucking reflex

When the index finger is inserted 3-4 cm into the mouth, the child makes rhythmic sucking movements. The reflex is absent in cases of paresis of the facial nerves, severe mental retardation, and severe somatic conditions. The sucking reflex in human children usually subsides between three and four years of age, which explains why in many cultures breastfeeding lasts until the age of three or four years, i.e. up to the age at which the child suckles on his own. US anthropologist Professor Katherine A. Dettwiler came to the conclusion that the need for sucking, i.e. The natural period of breastfeeding (expected by our children) can last from 2.5 to 7.0 years. (Dettwyler 1995).

Hemojaw reflex (Polyansky reflex)

When pressing on the child from two different sides of the head with the clean hands of the obstetrician, the child’s head bends from two different sides of the child’s skull, as a result of which the child’s mouth opens. The lethargy of the child after the reflex is diagnosed and the rapid depletion of the child’s blood supply is a natural consequence of the normal functioning of the reflex. The absence or weak expression of the reflex may be a consequence of lethargy in the hands of the obstetrician.

Search reflex (Kussmaul reflex)

When stroking the corner of the mouth, the lip lowers, the tongue deviates, and the head turns toward the stimulus. Pressing on the middle of the upper lip causes the mouth to open and the head to straighten. When you press on the middle of the lower lip, the lower jaw drops and the head bends. This reflex is especially pronounced 30 minutes before feeding. Pay attention to the symmetry of the reflex on both sides. The search reflex is observed up to 3-4 months, then fades away. Reflex asymmetry—unilateral paresis of the facial nerve. There is no reflex - bilateral paresis of the facial nerve, damage to the central nervous system.

Proboscis reflex

A quick tap on the lips with a finger causes the lips to stretch forward. This reflex lasts up to 2-3 months.

Palm-oral reflex (Babkin reflex)

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Video showing the Babkin reflex.

When pressing with the thumb on the area of ​​the newborn's palm, closer to the thenar, the mouth opens and the head flexes. The reflex is clearly pronounced in newborns. Sluggishness of the reflex, rapid exhaustion or absence indicate damage to the central nervous system. The reflex may be absent on the affected side with peripheral paresis of the arm. After 2 months it fades away by 3 months. disappears.

see also

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