Neurosis is one of the typical forms of pathology of the nervous system induced by failure of the brain cortical functions.
After discovery of the conditioned and unconditioned reflexes by I.P. Pavlov it became possible to study mechanisms of neurosis in experimental animals.
During classical conditioning two stimuli are presented to an organism in a specific sequence and the organism forms an association or connection between them. According to the basic model of conditioning an unconditioned stimulus (UCS) that elicits an automatic response is paired with a conditioned stimulus (CS). Eventually, the CS itself can elicit a response from the organism, without presentation of the UCS.
Studies of reflexes by I.P. Pavlov led to the discovery of the «law of power»: the more intense and sustained is the CS, in a certain range of intensities, the higher is the response. But if the intensity of the stimulus is too high, it causes a decrease rather than an increase in response. Extremely intense CS elicits a «phase state» of the brain cortex. When an animal is in the phase state the, it looks depressed, passive, and loses ability to reproduce previously elaborated conditioned responses (CR).
This condition is the result of overexertion of excitatory processes in the brain cortex. Failure of the brain cortical functions due to overexertion of the excitatory processes has been called the «neurosis with domination of inhibition».
Conditions for modeling of neurosis with domination of inhibition:
• extreme intensity of conditioned stimulus (intense light or sound);
• prolonged or repetitive effect of a strong stimulus;
• simultaneous action of different intense stimuli;
• complex or unfamiliar stimuli.