Conditional reflexes are ... Types of conditioned reflexes. Deceleration of conditioned reflexes

Conditional reflexes are reactions of the whole organism or some part of it to external or internal stimuli. They are manifested through the disappearance, weakening or strengthening of a certain activity.

Conditional reflexes are helpers of an organism, allowing it to react quickly to any changes and adapt to them.

History

The idea of a conditioned reflex was first put forward by the French philosopher and scientist R. Descartes. Somewhat later, the Russian physiologist I. Sechenov created and experimentally proved a new theory concerning the reactions of the organism. For the first time in the history of physiology, it was concluded that conditioned reflexes are a mechanism that is driven not only by segments of the spinal cord. In his work, the entire nervous system is involved. This allows you to keep in touch with the environment.

He studied the conditioned reflex Pavlov. This outstanding Russian scientist was able to explain the mechanism of the action of the cerebral cortex and the cerebral hemispheres. At the beginning of the XX century he created a theory of conditioned reflexes. This scientific work has become a real revolution in physiology. Scientists have been shown that conditioned reflexes are reactions of the body that are acquired throughout life, based on reflexes of unconditioned ones.

Instincts

Certain reflexes of the unconditioned type are characteristic for each species of living organisms. They are called instincts. Some of them are very complicated. An example of this can be the bees that honeycomb molds, or birds, nesting nests. Due to the presence of instincts, the body is able to adapt optimally to environmental conditions.

Unconditioned reflexes are congenital. They are inherited. In addition, they are referred to the category of species, since they are characteristic of all representatives of a certain species. Instincts are permanent and persist throughout life. They manifest themselves on adequate stimuli, which are attached to a single receptive field. Physiologically unconditioned reflexes are closed in the stem part of the brain and at the level of the spinal cord. They are manifested through an anatomically expressed reflex arc.

As for the monkey and the man, they can not exercise the greater part of the complex unconditioned reflexes without the involvement of the cerebral cortex. In violation of its integrity, pathological changes occur in unconditioned reflexes, and some of them simply disappear.

Classification of instincts

Unconditioned reflexes are very strong. Only under certain conditions, when their manifestation becomes unnecessary, they can disappear. For example, a canary, domesticated about 300 years ago, currently does not have the instinct for nesting. There are the following types of unconditioned reflexes:

- Instinct of self-preservation, which is the reaction of the body to a variety of physical or chemical irritants. Such reflexes, in turn, can manifest themselves locally (withdrawal of the hand) or be complex (escape from danger).
- Nutritional instinct, which is caused by hunger and appetite. This unconditioned reflex includes a whole chain of successive actions - from seeking prey to attacking it and further eating.
- Parental and sexual instincts associated with the maintenance and reproduction of the species.

- Comfortable instinct, serving to keep the body clean (bathing, scratching, shaking, etc.).
- An approximate instinct, when the eyes and head turn to the side of the stimulus. This reflex is needed to save life.
- The instinct of freedom, which is especially pronounced in the behavior of animals in captivity. They constantly want to break free and often die, refusing water and food.

The emergence of conditioned reflexes

During life, the acquired reactions of the organism are added to the inherited instincts. They are called conditioned reflexes. They are acquired by the body as a result of individual development. The basis for obtaining conditioned reflexes is life experience. Unlike instincts, these reactions are individual. They may be present in some representatives of the species and absent from others. In addition, the conditioned reflex is a reaction that may not persist throughout life. Under certain conditions, it is developed, fixed, disappears. Conditional reflexes are reactions that can occur on various stimuli applied to different receptor fields. This is their difference from instincts.

The mechanism of the conditioned reflex is closed at the level of the cerebral cortex. If you delete it, then only the instincts remain.

Formation of conditioned reflexes occurs on the basis of unconditioned ones. To implement this process, it is necessary to fulfill a certain condition. At the same time, any change in the external environment must, in time, be combined with the internal state of the organism and be perceived by the cerebral cortex with simultaneous unconditioned reaction of the organism. Only in this case there is a conditioned stimulus or signal that facilitates the emergence of a conditioned reflex.

Examples

For the appearance of such an organism reaction, as the salivation of knives and forks, and also the knocking of a cup for feeding the animal (in humans and dogs, respectively), an indispensable condition is the repeated coincidence of these sounds with the process of providing food.

Similarly, the sound of a bell or the inclusion of a bulb will cause bending of the dog's paw if these phenomena repeatedly occurred accompanied by electric stimulation of the animal's leg, which resulted in the appearance of a flexural reflex of the unconditioned type.

The conditioned reflex is the withdrawal of the child's handles from the fire and the subsequent crying. However, these phenomena will only occur if the fire, even once, coincides with the burn.

Components of reactions

The reaction of the body to irritation is a change in breathing, secretion, movement, etc. As a rule, unconditioned reflexes are rather complex reactions. That's why they consist of several components. For example, a defensive reflex is accompanied not only by defensive movements, but also by increased breathing, acceleration of the activity of the heart muscle, changes in the composition of the blood. In this case, there may be a voice reaction. As for the food reflex, there are also respiratory, secretory and cardiovascular components.

Conditional reactions usually reproduce the structure of unconditioned ones. This occurs in connection with the excitation of the same nerve centers by the stimuli.

Classification of conditioned reflexes

Acquired responses of the body to various stimuli are subdivided by species. Some of the existing classifications are of great importance in solving not only theoretical but also practical problems. One of the areas of application of this knowledge is sports activities.

Natural and artificial reactions of the body

There are conditioned reflexes that arise when signals act, characteristic of the constant properties of unconditioned stimuli. An example of this is the appearance and smell of food. Such conditioned reflexes are natural. They are characterized by the speed of production and greater durability. Natural reflexes, even in the absence of subsequent reinforcement, can be retained throughout life. The value of the conditioned reflex is especially great in the very first stages of the organism's life, when it adapts to the environment.
However, reactions can also be developed on a variety of indifferent signals, such as smell, sound, temperature change, light, etc. Under natural conditions, they are not irritants. It is these reactions that are called artificial. They are produced slowly and in the absence of reinforcement quickly disappear. For example, artificial conditioned reflexes of a person are reactions to ringing, touching the skin, weakening or amplification of lighting, etc.

The first and the highest order

There are such kinds of conditioned reflexes that are formed on the basis of unconditioned reflexes. These are first-order reactions. There are also higher categories. Thus, the reactions that are developed on the basis of the already existing conditioned reflexes are referred to higher-order reactions. How do they arise? In the development of such conditioned reflexes, the conditioned signal is reinforced by well-conditioned conditioned stimuli.

For example, irritation in the form of a bell is constantly reinforced with food. In this case, a conditioned reflex of the first order is produced. On its basis, the reaction can also be fixed to another stimulus, for example, to light. This will become a conditioned reflex of the second order.

Positive and negative reactions

Conditional reflexes can influence the activity of the organism. Such reactions are considered positive. The manifestation of these conditioned reflexes can serve as secretory or motor functions. If there is no activity of the organism, then the reactions are classified as negative. For the process of adaptation to the constantly changing conditions of the environment of existence, both one and the second species are of great importance.

At the same time, there is a close relationship between them, since the manifestation of one type of activity necessarily oppresses the other. For example, when the "Smile!" Command sounds, the muscles are in a certain position. At the same time motor reactions (running, walking, etc.) are inhibited.

The mechanism of education

Conditional reflexes occur when the conditioned stimulus and the unconditioned reflex act simultaneously. In doing so, certain conditions must be met:

- unconditioned reflex biologically stronger;
- the manifestation of the conditioned stimulus somewhat outstrips the action of the instinct;
- the conditioned stimulus is necessarily reinforced by the action of the unconditioned stimulus;
- the body should be in a wakeful state and be healthy;
- the condition for the absence of extraneous stimuli, which produce a distracting effect, is observed.

The centers of conditioned reflexes in the cerebral cortex establish a temporary connection (closure) between themselves. In this case, the stimulation is perceived by the cortical neurons, which are contained in the arc of the unconditioned reflex.

Deceleration of conditioned reactions

In order to ensure adequate behavior of the organism and for better adaptation to the surrounding conditions, one development of conditioned reflexes will not be enough. It takes the opposite in the direction of the action. It is the inhibition of conditioned reflexes. This is the process of eliminating those reactions of the body in which there is no need. According to the theory developed by Pavlov, certain types of cortical inhibition are distinguished. The first one is unconditional. It appears as a response to the action of some extraneous stimulus. There is also internal inhibition. It is called conditional.

External braking

This reaction has been given this name due to the fact that its development is facilitated by processes occurring in those parts of the cortex that do not participate in the implementation of reflex activity. For example, an extraneous smell, sound or light change before the onset of an eating reflex can reduce it or promote complete extinction. A new stimulus is a brake for the conditioned reaction.

Nutritional reflexes can be eliminated and painful irritants. Deceleration of the body's reaction is facilitated by bladder overflow, vomiting, internal inflammatory processes, etc. All of them suppress food reflexes.

Internal braking

It occurs when the received signal is not supported by an unconditioned stimulus. Internal inhibition of conditioned reflexes occurs if, for example, an animal during the day is periodically switched on before the eyes of an electric bulb, while not bringing food. It has been experimentally proven that saliva production will decrease every time. As a result, the reaction will fade completely. However, the reflex will not disappear without a trace. He simply stalled. This is also proved experimentally.

Conditional inhibition of conditioned reflexes can be eliminated the next day. However, if this is not done, then the body's reaction to this stimulus will subsequently disappear forever.

Types of internal inhibition

Classify several types of elimination of the body's response to stimuli. So, at the basis of the disappearance of conditioned reflexes, which are simply not needed in these specific conditions, there is a fading inhibition. There is another kind of this phenomenon. This is a differential, or differentiated, inhibition. Thus, an animal can distinguish between the number of metronome strokes that will bring food to it. This occurs when the conditioned reflex is preliminarily worked out. The animal distinguishes between stimuli. This reaction is based on internal inhibition.

The importance of eliminating reactions

Conditional braking plays a significant role in the life of the body. Thanks to him, the process of adaptation to the environment is much better. The possibility of orientation in a variety of complex situations gives a combination of excitation and inhibition, which are two forms of a single nervous process.

Conclusion

There are an infinite number of conditioned reflexes. They are the factor that determines the behavior of a living organism. With the help of conditioned reflexes, animals and man adapt themselves to their environment.

There are many indirect signs of body reactions that have a signal meaning. For example, an animal, knowing in advance about the approach of danger, builds its behavior in a certain way.

The process of elaborating conditioned reflexes, which belong to the higher order, is a synthesis of temporal links.

The basic principles and patterns manifested in the formation of not only complex, but elementary reactions, are the same for all living organisms. From this follows an important conclusion for philosophy and natural sciences that the human brain can not but obey the general laws of biology. In this regard, it can be objectively studied. However, it should be borne in mind that the activity of the human brain has a qualitative specificity and a fundamental difference from the work of the animal's brain.