Fig. 5. Investigation of the ability to form new memories showed that anterograde amnesia was less pronounced after S (+)- (P = 0.009) or R (−)-ketamine (P = 0.028) than after racemic ketamine at 5 min after drug injection. Bars represent n = number of subjects per drug who correctly recalled the memory cards presented during the study at 60 min after drug injection. *Significant difference between racemic ketamine and S (+)-ketamine. †Significant difference between racemic ketamine and R (−)-ketamine.