Selective blockade of the mGluR5 with a negative allosteric modulator 2-chloro-4-[2-[2,5-dimethyl-1-[4-(trifluoromethoxy)phenyl]imidazol-4-yl]ethynyl]pyridine improved cognitive function in these mice [87], while another selective mGluR5 blocker 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine restored learning and memory deficits in the AD mice by eliminating synaptic dysfunction [79,88]. Here, GRM5 is linked to Alzheimer disease.