FMR1 and fragile X syndrome: This fundamental result, the increase in mGluRI-dependent LTD in correlation with FMRP loss in mice, was later confirmed by many independent studies (Todd et al., 2003; Antar et al., 2004; Aschrafi et al., 2005; Desai et al., 2006; Huang et al., 2015) giving rise to the formulation of the “mGluR theory of FXS” (Bear et al., 2004; Bear, 2005), which will eventually rise to almost dominate the field of FXS research.