During the first probe trial, adult (solid bars in A,B,D,E; thick box plots in C,F) and aged (open bars in A,B,D,E; thin box plots in C,F) mice searched the platform preferentially at its correct location. (A, inset) The scheme of the maze. (Thick bar) Landmark position, (T) target zone, (1, 2, 3) control zones (incorrect). (A,B,C) Performance of all adults (n = 22) and aged (n = 32) mice. (D,E,F) Performance of selected adult (n = 15) and aged (n = 15) mice. These mice were selected for undergoing the next probe trials. Number of entries into and time spent in zones are represented with means plus S.E.M. The preference indices are shown with standard box plots. ***P < 0.001, difference between the target zone and the other zones within both groups (Newman-Keuls post hoc after a significant effect of zone); ++P < 0.01, as compared with the aged group within the same zone (Newman-Keuls post hoc after a significant effect of the interaction between group and zone); ###P < 0.001, as compared with chance level (25%) (Wilcoxon signed-rank test).
