FMR1 and fragile X syndrome: The present study employs both Fmr1 knockout (KO) 1 and KO2 mouse models of FXS40–42 and covers multiple aspects of blarcamesine’s action: an evaluation of three neurobehavioral paradigms representing key cognitive and behavioral aspects of the FXS phenotype, and parallel assessments of several key signaling pathways in a S1R-enriched region.