[Latent inhibition and extinction of passive avoidance in mice C57BL/6J AND DBA/2J]

The study was carried out in mice C57BL/6J and DBA/2J for comparative analysis of two interference processes: latent inhibition and extinction of passive avoidance produced with an unconditioned aversive stimulus of different parameters (0.5 and 0.25 mA). With a strong training to new stimulus, impairment of extinction has been detected only in mice DBA/2J. Reduction in the strength of punishment during training was accompanied by acceleration of extinction in mice C57BL/6J and its appearance in mice DBA/2J. The learning of passive avoidance in strong and weak reinforcement was the same for both strains of mice. Interline differences were found also in the analysis of latent inhibition. With strong and weak training to conditional stimulus, lost of novelty by repeated an 8-fold pre-exposures to the experimental chamber, in DBA/2J mice, in contrast to C57BL/6J, latent inhibition was disrupted. In addition, DBA/2J mice showed impairment of extinction with weak training to non-relevant stimulus.