Place navigation learning using proximal landmarks and memory. 6A - Acquisition. Learning performances in 28 trials of 2 min were measured as latency to reach the platform in sec, and are represented in blocks of 4 trials. ^P <0.05, ^^P < 0.01, ^^^P <0.001 vs. first block; * P < 0.05, **P < 0.01 WT vs. KO, Bonferroni post hoc. 6B - Probe test. Retention was assessed as the number of the crossings of the platform area in a 1 min test before and after acquisition. ^^^ P < 0.001 vs. before acquisition; ** P < 0.01 WT vs. KO, Bonferroni post hoc. Thigmotaxis and floating time were measured during the acquisition phase and the subsequent probe test. Average thigmotaxis time in sec (6C). ** P < 0.01, WT vs KO, Student's t-test. Thigmotaxis time course as percent of total time (6D). ^ P < 0.05, ^^P < 0.01 vs. trial 1, Bonferroni post hoc. Average floating time in sec (6E). **P < 0.01 WT vs KO, Mann-Whitney. Floating time course as percent of total time (6F). WT n = 10, KO n = 10.