Corner visit frequency of TDO2 WT and GKO mice during drinking and non-drinking sessions in R1 and R2. (a) Over the 2-day drinking session, in R1, both TDO2 WT and GKO mice retained their corner visit behavior. (b) By contrast, in R2, WT and GKO mice increased corner visit frequency in the 2-day drinking session. There was no significant genotype effect relating to this. (c) Both WT and GKO mice increased corner visits on the first execution of non-drinking session in R1. (d) The increase in corner visits during the non-drinking session on the first test day was observed only in WT mice, but there was no significant genotype effect at each level of repeated contrast. Data showed mean±SEM. The visit frequency of test day 1 or 2 was compared to that on the previous day by repeated contrast. *p<0.05, **p<0.01, ***p<0.001, repeated contrast. Total n=18 WT and n=17 GKO mice.