THE MORRIS WATER-ESCAPE TASK IN MICE - STRAIN DIFFERENCES AND EFFECTSOF INTRA-MAZE CONTRAST AND BRIGHTNESS

The Morris water-escape task is an extensively used experimental parad igm to assess the spatial discrimination performance and effects of br ain lesions and drugs on this performance. In the first experiment, we compared the acquisition of this task by different strains (CFW1, BAL E, NMRI, and C57BL) of mice and their performance in a probe trial. In a second experiment, C57BL mice were tested in Morris mazes where bla ck and white tanks were combined with white or black platforms to inve stigate if and how the contrast between the tank and the platform affe cts the performance of the mice. In addition, four brightness conditio ns were compared to investigate whether or not the degree of brightnes s of the tank itself affects the learning performance. The results of these experiments indicated that 1. mice could readily learn the Morri s task 2. one of the contrast conditions affected the swimming speed, 3. the maze brightness per se did not affect water escape performance at all, and that 4. the swimming speed can strongly bias the outcome o f Morris water-escape experiments in mice. Copyright (C) 1996 Elsevier Science Inc.