G Water-maze place navigation, swim path during acquisition and reversal (ANOVA: day F4,104=21.14 p<0.0001, genotype F1,26=13.11 p=0.0013, age x genotype F2,26=8.204 p=0.0017). All groups learned: controls showed reduced performance with increasing age, mutants showed poor performance already at 9- and 14-months. 