1. A method of normalizing or attenuating a plurality of behavioral deficits associated with Fragile X Syndrome (“FXS”) in an individual having Fragile X Syndrome, comprising administering to said individual, a therapeutically effective amount of (4-amino-8-(2-fluoro-6-methoxy-phenyl)-N-propyl-cinnoline-3-carboxamide) or a pharmaceutically acceptable salt thereof.