The effect of Wnt1 in the amygdala on fear learning and memory. a, b, Cresyl violet staining of parallel sections showing the absence of damage in vehicle- (a) or Wnt1- (b) infected regions. c, Activity measures of mice receiving injections of vehicle or Wnt1 and placed in an open-field apparatus for 10 min. n = 13 for vehicle, n = 15 for Wnt1. d, Acquisition curve showing percentage time spent freezing during each tone before footshock presentation. n = 15 for vehicle, n = 23 for Wnt1. e, f, Animals were injected with either vehicle or Wnt1 before training, and vehicle or Wnt1 after training (Pre-training/Post-training). e, Percentage time spent freezing when tested 48 h after fear conditioning, and presented with 15 tone presentations. f, Freezing data from e, presented in three blocks of five tone presentations. White bars are Veh/Veh, gray bars are Veh/Wnt1, and black bars are Wnt1/Veh animals. For both e and f, n = 8 for Veh/Veh, n = 7 for Veh/Wnt1, n = 12 for Wnt1/Veh. Data are mean ± SEM; **p < 0.01, *p < 0.05, ANOVA with post hoc analyses.