Effects of pre- and post-trial caffeine administrations on simultaneous visual discrimination in three inbred strains of mice.

BALB/cJ, DBA/2J, and C57BL/6J mice were injected with caffeine and tested, in the five choice Yerkes-Thompson Bryant-Bovt Nitti apparatus for patterns discrimination, in two sets of experiments. In the first the patterns were opposite oriented oblique bars, in the second U-shaped figures, one opened toward the right, the other toward the left. As concerns the saline injected animals in both sets of experiments, the BALB mice showed the highest learning abilities; in the second set the C57 strain, whose performance had not been different from that of the DBA mice in the first set, performed at the lowest level. Pre- and post-trial caffeine (5 mg/kg) administrations were followed by performance impairment in the BALB strain, while performance improvements were evident in the drugged animals belonging to the other two strains.