GRM5 and Cognitive impairment: In line with the potentiating actions of mGluR5 antagonists on the noncompetitive NMDA receptor antagonists-induced responses such as locomotor hyperactivity, prepulse inhibition [11,12] and cognitive deficits [13,27], these animal behavioral studies also reveal that activation of mGluR5 could ameliorate the behavioral abnormalities associated with NMDA receptor deficiency.