[Dynamics of changes in the orienting response of rabbits to visual stimuli of growing intensity].

The process of formation and the structure of orienting reaction (OR) to rhythmic photic stimuli of growing intensity (beginning with brightnesses near the visibility threshold) was studied in alert non-immobilized rabbits. Motor (movements of the fore and hind paws and the ears) and the vegetative (respiratory) OR components were recorded. No dependence of the emergence of different type reactions on the intensity of the stimulus was disclosed. All the studied kinds of the animal's behavioral responses begin to appear for the first time in a very narrow range of brightness. OR to presented stimuli is not completely extinguished. The process of OR extinction is of a wave-like nature. It is assumed that the structure of the rabbit OR to photic stimuli of low intensities and short durations is determined not so much by physical parameters of the stimulus, as by the animal's condition.