ИСТИНА

Laboratory mice (inbred and outbred) are unable ability to solve the extrapolation task (the food bait moves out of animal view and it could be found if move in the same direction). The small proportions of mice, nevertheless, were able to solve this elementary logic task with the performance scores significantly higher in comparison with the chance level. This served as the prerequisite to perform the selection for high scores of extrapolation task solutions. Mice of the first selection generations (F1-F10) of the new EX strain solved the task successfully in the proportions, significantly above the 50% chance level. In further generations the level of successful solutions by mice of the selected strain became unstable. At the same time mice of these generations were significantly superior in comparison with non-selected mice in the success of puzzle-box test solutions. On these grounds the selection of mice for high and low performance in puzzle-box solution scores had been started and mice of three selection generations (in "plus" and “minus” directions) were tested using the simplified puzzle-box test protocol (1 day testing). The puzzle-box test contained 4 stages with the underpass into the dark, safe compartment being unobstructed, masked by wood-shavings and masked by the light plug (presented twice) Mice of the “plus” substrain demonstrated significantly higher plug-stage task solutions than mice, selected for “minus” performance. The detailed analysis revealed that the “plus” substrain mice were more efficient in the realization of solution, while mice of “minus” groups made desperate and unsuccessful attempts to remove the plug (performing the manipulation movements). Thus, mice of both groups understood the object permanence rule, the higher percentages of real task solutions by “plus” group mean their higher executive function performance.