Latent Inhibition and Extinction of a Conditioned Passive Avoidance Reaction in C57BL/6J and DBA/2J Mice

摘要

Comparative analysis of the development of two interference processes – latent inhibition and the extinction of a conditioned passive avoidance reaction acquired using unconditioned stimuli with different levels of aversiveness (0.5 and 0.25 mA) – was performed in C57BL/6J and DBA/2J mice. In "strong" training, impairment of extinction to a new stimulus was seen only in DBA/2J mice. Decreases in punishment strength during training were accompanied by acceleration of extinction in C57BL/6J mice and the appearance of extinction in DBA/2J mice. Formation of the memory trace using both "strong" and "weak" reinforcement was identical for mice of both strains. Interstrain differences were also seen on analysis of latent inhibition. In "strong" and "weak" training, conditioned stimuli which had lost novelty due to eight pre-exposures in the experimental chamber showed latent inhibition in DBA/2J mice but not C57BL/6J mice. In "weak" training, DBA/2J mice also showed no extinction of the conditioned passive avoidance response to the irrelevant stimulus.