Figure 3. Lack of peripheral serotonin does not result in attention impairment.

Ability to learn the association between the stimulus light and reward in WT and Tph1 (−/−) mice showed a strong trend indicating that aged Tph1 (−/−) mice may acquire this association more slowly, however, overtime they demonstrated successful learning across daily sessions (A). Overall, aged mice of both genotypes showed a significant deficit in performance during trials of 1 (**P<0.01) and 2 seconds (*P<0.05) (B).