Reflex is the body's response to internal or external irritation, carried out and controlled by the central nervous system. The first scientists who developed ideas about human behavior, which had previously been a mystery, were our compatriots I. P. Pavlov and I. M. Sechenov.
What are unconditioned reflexes?
The unconditioned reflex is an innate stereotyped reaction of the organism 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 spinal cord, the cerebral cortex does not take part in their formation. The value 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.
Which reflexes are unconditioned?
The unconditioned reflex is the main form of activitynervous system, 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. Children also experience constriction of the pupils, 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 conditional. They are formed on the basis of inherited ones, subject to the influence of an external stimulus (time,knock, light, etc.). 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 exposure allows you to develop a conditioned reflex. In this case, a so-called temporal 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.
Independent category of conditioned reflexes
It is customary to single out conditioned reflexes of a motor nature developed during life, that is, skills or automated actions, into an independent category. 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, consciousnessare released 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 errors, 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 if an even greater stimulus occurs.
Compare unconditioned and conditioned reflexes
As mentioned above, these reactions differ in the nature of their occurrence and have a different mechanism of formation. 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 unconditioned reflexes (innate): 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, everyoneorganism, they are individual (their own). Their main function is the adaptation of a living being to changing conditions. Their temporary connection (centers of reflexes) is created in the cerebral cortex. An example of a conditioned reflex is the reaction of an animal to a nickname, or the reaction of a six-month-old child to a bottle of milk.
Unconditioned reflex scheme
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 associated 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 characteristics of inherited responses?
- The innate nature of the body's response to stimuli.
- The constancy of neural connections between certain types of stimuli and responses.
- Species character:reflexes of the same type proceed identically in all representatives of a particular type of living organisms, they differ only in the characteristic features of animals that belong to different species. For example, the instinctive care for offspring of all bees in a swarm is exactly the same, but differs from the same instincts of wasps or ants.
- Inborn unconditioned reflexes do not depend on personal experience at all, they practically do not change during the life of the animal.
- In higher organisms, this type of reaction is usually carried out by the lower parts of the nervous system, the involvement of the cerebral cortex has not been recorded.
Unconditional instinct and animal reflex
The exceptional constancy of the neural connection underlying the unconditional instinct is due to 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, features 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 affected, 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 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 thatsuch 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 body's adaptability to external environmental conditions.
Unconditional inhibition
In the process of life, each organism is regularly exposed - both from the outside and from the inside - to various stimuli. Each of them is 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 pathogen, being stronger, leads tothe fading of the old. 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 alarming 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.
Besides, there is a protective (outrageous) inhibition. It occurs as a response to a very strong stimulus that requires the body to act beyond its capabilities. The level of such influence 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 promotes so-called biological caution.
