Reflex is the response of the body to internal or external stimulation, carried out and controlled by the central nervous system. The first scientists who developed ideas about human behavior, which were a mystery before, were our compatriots I.P. Pavlov and I.M. Sechenov.
What are unconditioned reflexes?
The unconditioned reflex is a stereotypical reaction of the organism to the influence of the internal or the environment that is inherited by the offspring from parents. It persists in a person throughout his life. Reflex arcs pass through the brain and spinal cord, the cerebral cortex does not participate in their formation. The significance of the unconditioned reflex is that it provides the adaptation of the human body directly to those environmental changes that often accompanied many generations of its ancestors.
What reflexes are unconditioned?
An unconditioned reflex is the main form of activity of the nervous system, an automatic reaction to a stimulus. And since various factors influence a person, reflexes are different: food, defensive, orientative, sexual ... Salivating, swallowing, and sucking are food. Defensive coughing, blinking, sneezing, pulling limbs away from hot objects. Indicative reactions include turning the head, mowing the eyes. Sexual instincts are related to reproduction, as well as care for offspring. The value of the unconditioned reflex is that it ensures the preservation of the integrity of the body, maintains a constant internal environment. Thanks to him, reproduction takes place. Even in newborn children, an elementary unconditioned reflex can be observed - this is sucking. By the way, it is the most important. In this case, the irritant is touching the lips of an object (nipples, mother’s breasts, toys or fingers). Another important unconditioned reflex is blinking, which occurs when the foreign body approaches the eye or touches the cornea. Such a reaction refers to a protective or defensive group. Also, in children there is a narrowing 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 the inherited, subject to the influence of an external stimulus (time, knock, light, and so on). A striking example is the experiments conducted on dogs by academician I.P. Pavlov. He studied the formation of this type of reflexes in animals, was the developer of a unique technique for their preparation. So, to develop such reactions, you must have a regular stimulus - a signal. It starts the mechanism, and repeated repetition of the stimulus allows you to develop a conditioned reflex. In this case, the so-called temporary connection arises between the arcs of the unconditioned reflex and the centers of the analyzers. Now the basic instinct awakens under the influence of fundamentally new signals 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 creature during life can develop many different conditioned reflexes that form the basis of its 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 distinguish into the independent category the conditioned motor reflexes 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, for the entire period of his life, a person masters a lot of special motor skills that are associated with his profession. They are the foundation of our behavior. Thinking, attention, consciousness are freed during operations that have achieved automatism and become the realities of everyday life. The most successful way of mastering the skills is the systematic execution of the exercise, the timely correction of the errors noted, as well as knowledge of the ultimate goal of any task. In the event that the conditioned stimulus is not supported for some time by the unconditioned, its inhibition occurs. However, he does not disappear at all. If after some time the action is repeated, the reflex will recover quite quickly. Inhibition can also occur if an irritant of even greater strength occurs.
Compare unconditioned and conditioned reflexes
As mentioned above, these reactions differ in the nature of the occurrence and have a different formation mechanism. In order to understand what the difference is, just compare the unconditioned and conditioned reflexes. Thus, the living creature has the first ones 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 trunk of the brain or spinal cord. As an example, we give some unconditioned (innate) reflexes : 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 the conditioned reactions. They are acquired throughout life, can change or disappear, and, no less important, in each organism they are individual (their own). Their main function is to adapt a living being to changing conditions. Their temporary connection (centers of reflexes) is created in the cortex of the cerebral hemispheres. 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. Pavlova, the general scheme of unconditioned reflexes is as follows. These or other receptor nervous devices are affected by various stimuli of the internal or external world of the body. As a result, the resulting irritation transforms the whole process into the so-called phenomenon of nervous excitement. It is transmitted through nerve fibers (like 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 a given part of the body. It turns out that certain stimuli are naturally connected with one or another activity in the same way as the cause and 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 deal with the phenomenon we are considering. So, what are the features of inherited reactions?
- Congenital nature of the body's response to stimuli.
- The constancy of nerve connections between certain types of irritations and responses.
- Species nature: homogeneous reflexes proceed identically in all representatives of a particular species of living organisms, they differ only in the characteristic features of animals that belong to different species. For example, the instinctive care of the offspring of all bees in a swarm is exactly the same, but differs from the same instincts of wasps or ants.
- Congenital unconditioned reflexes generally do not depend on personal experience; they practically do not change during the life of the animal.
- In higher organisms, this type of reaction, as a rule, is carried out by the lower parts of the nervous system, the participation of the cerebral cortex is not fixed.
Unconditional instinct and reflex of animals
The exceptional constancy of the neural connection underlying the unconditional instinct is explained by the fact that all animals are born with the nervous system. She is already able to respond properly to specific environmental stimuli. For example, a creature may flinch at a sharp sound; digestive juice and saliva will be released when food enters the mouth or stomach; it will blink with visual irritation and so on. Not only individual unconditioned reflexes, but also much more complex forms of reactions are innate in animals and humans. They are called instincts.
The unconditioned reflex, in fact, is not a completely monotonous, stereotyped, transfer reaction of the animal to an external stimulus. It is characterized, although elementary, primitive, but still variability, variability, depending on external conditions (strength, characteristics of the situation, the position of the stimulus). In addition, it is influenced by the internal conditions of the animal (decreased or increased activity, posture, and others). So, still I.M. Sechenov in his experiments with decapitated (spinal) frogs showed that when the fingers of the hind legs of this amphibian are exposed, the opposite motor reaction occurs. From this we can conclude that the unconditioned reflex still has adaptive variability, but to insignificant limits. As a result, we obtain that the balance of the organism and the 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 its sense of smell, searches for larvae of another insect under the bark. He pierces the bark and lays his egg in the found victim. This completes all of his action, ensuring the continuation of the genus. There are complex unconditioned reflexes. Instincts of this kind consist of a chain of actions, the totality of which ensures the continuation of the genus. 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 will be the same for all representatives of the same species. An example is a turtle. All species of these amphibians draw their heads and limbs into their carapace in case of danger. And all the hedgehogs bounce and make a hissing sound. In addition, you should be aware that not all unconditioned reflexes arise at the same time. These reactions vary according to age and season. For example, the breeding season or the motor and sucking actions that appear in the 18-week-old fetus. Thus, unconditioned reactions are peculiar developments for conditioned reflexes in humans and animals. For example, in cubs, as they grow older, a transition to the category of synthetic complexes occurs. They increase the body's adaptability 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 different 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 coherence and orderliness. This is explained by the fact that in the body inhibition of unconditioned reflexes occurs. This means that the most important reflex at a particular point in time delays the secondary. Usually, external inhibition can occur at the moment of the start of another activity. The new pathogen, as a stronger one, leads to the attenuation of the old one. And as a result, previous activities will automatically cease. For example, a dog eats, and at that moment the doorbell rings. The animal instantly stops eating and runs to meet the newcomer. There is a sharp change in activity, and the salivation of the dog at this moment stops. Some inborn reactions are also referred to as unconditioned inhibition of reflexes. In them, certain pathogens cause a complete cessation of certain actions. For example, the alarming clucking of a chicken causes the chickens to freeze and snuggle to the ground, and the onset of darkness forces the kenar to stop singing.
In addition, there is protective (beyond) braking. It arises as a response to a very strong stimulus, requiring 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 will be the frequency of the flow of nerve impulses that it generates. However, if this flow exceeds certain limits, a process will arise that will begin to impede the passage of excitation along the neural circuit. The flow of pulses along the reflex arc of the spinal cord and brain is interrupted, as a result of inhibition, which preserves the executive organs from complete exhaustion. Which conclusion follows from this? Thanks to the inhibition of unconditioned reflexes, the body distinguishes from all possible options the most adequate, able to protect from excessive activities. This process also contributes to the manifestation of so-called biological caution.