GRM5 and age: In addition, the normal expression of mGluR5 protein in the face of null mGluR-LTD/P at 8 months APP/PS1 (Figure 2), and the previous finding that wild-type levels of mGluR-LTD can be restored by targeting the kinase PERK (Yang et al., 2016), are both consistent with the notion that the uncoupling of type 1 mGluRs is a main contributing factor to age-related cognitive decline (Nicolle et al., 1999).