[The over-reinforced conditioned reflex--a highly adaptive behavioral system].

Specialized (according to Pavlov) instrumental alimentary conditioned reflexes (CR) were studied after extremely prolonged training (2500-3000 pairings). It was established that these CR were characterized by extremely rapid extinction (till 15-20 absences of instrumental reaction after only 2-7 presentations of non-reinforced conditioned stimulus, despite the classical statement on difficult extinction of consolidated CR) independently of typological features and level of alimentary motivation of animals. The results obtained allow us to set aside such reflexes as a special category of CR which are underlined by neurophysiological and neurochemical mechanisms distinct from those of commonly used in experimental practice less trained CR. The phenomenon described may be interesting in studying the processes of learning and long-term memory.