a strong trendP = 0.06
Both WT and Tph1 (−/−) mice were able to learn the association between the stimulus light and reward (session effect: F (12,493) = 93.385; P<0.001) however there was a strong trend indicating that aged Tph1 (−/−) mice may acquire this association slower (age×genotype: F (36, 493) = 1.398; P = 0.06; Figure 3A ).