FMR1 and fragile X syndrome: We assessed whether the CB1 receptor neutral antagonist, NESS0327, would modify the cognitive deficit observed in the Fmr1 KO mice (Figure 4A), in a similar manner to rimonabant, in order to find out if the inverse agonist characteristic of rimonabant over CB1 receptors would be relevant for targeting the cognitive deficit in the fragile X syndrome mouse model.