Inhibition is a physiological process in the central nervous system that results in a delay in arousal. Inhibition can not spread like excitement (see), being a local process. Braking occurs at the time of the meeting of two excitations, one of which is inhibitory, and the other is inhibited.
The process of inhibition was first shown in 1862 by the Russian physiologist I. M. Sechenov. The frog made a brain incision at the level of the visual mounds with the removal of the cerebral hemispheres. The time of the hind leg withdrawal reflex was measured when it was immersed in a solution of sulfuric acid (the Turk method). When a salt crystal was applied to the incision of the visual mounds , the reflex time increased. The salt crystal, irritating the visual cusps, causes arousal, which descends to the spinal centers and inhibits their activity.
In the formation of the behavioral reactions of animals and humans, along with the conditioned-reflex excitation in the central nervous system, there are always processes of conditioned-reflex inhibition. There are external (unconditional) and internal (conditional) inhibition.
Protective braking. The term "protective inhibition" should be understood as the property of the inhibitory process to protect cells from dangerous for their life and performance shifts associated with prolonged or excessively strong arousal. The theory of protective inhibition was created and substantiated by I.P. Pavlov .Go
Daily natural sleep can serve as an example of protective inhibition, but the most clearly protective inhibition is found in the case of transboundary inhibition, which occurs under the influence of super-strong stimuli.
The theory of protective-compensatory inhibition function is of considerable interest for medical practice and in some cases has led to undoubted practical achievements (the use of sedatives in the treatment of traumatic shock , hypothermia during surgical interventions, etc.).
External inhibition is associated with the activity of the reticular formation of the brain. It arises in case of a sudden appearance of an outsider for the observed reaction of the stimulus and is manifested in the fact that the conditioned reflex (see) does not form at all or its formation stops. A type of external inhibition is limiting inhibition, which occurs with an excessive increase in the strength of the conditioned stimulus.
Internal inhibition, or conditional, is a specific cortical and occurs when the conditioned stimulus is not supported by an unconditioned one. Depending on the conditions for the formation of internal braking, the following types of it are distinguished: extinctive, differential, conditional brake, retarded. Fading deceleration develops if, after the elaboration of a conditioned reflex, the conditioned stimulus is not supported by an unconditioned one. As a result, the conditioned reflex weakens or completely fades away. Differentiation inhibition arises with constant reinforcement of the conditioned stimulus and non-reinforcement of an outsider, the conditioned reflex arises only on the conditioned stimulus. Internal braking is produced in the presence of the so-called conditional brake. If the conditioned signal A is always supported by an unconditioned stimulus, and the combination of signals B + A is not supported, then there will be no conditioned reflex to the signals B + A. Thus, the signal A causes a conditioned reflex, and the addition of the signal B to it causes the inhibition of the conditioned reflex. Signal B is called conditional brake. Delayed inhibition occurs when the conditioned stimulus is supported by an unconditional one after a considerable time interval. With an increase in the interval to 3-5 minutes and more appropriately, the manifestation of the conditioned reflex reaction is also postponed. In the first minutes after the conditioned stimulus, inhibition of the conditioned reflex reaction is observed. Internal inhibition is an important mechanism in the adaptive activity of animals, especially humans. Different types of internal inhibition develop in the process of individual development of the organism. In humans, especially in children, internal inhibition must be brought up, which is of great importance in the pedagogical process.