GRM1 and depressive symptom measurement: Consistent with the mechanism of DHPG-induced synaptic depression described previously (McCutcheon et al., 2011a), this DHPG-induced LTD was completely abolished by the mGlu1 antagonist LY367385 (50 μM; Figures 1D,F) whereas it remained unaltered with the inclusion of the mGlu5 antagonist MTEP (50 μM; Figures 1E,F).