An mGluR antagonist; the active component of (±)-MCPG; inhibits ACPD-induced intracellular calcium increases in CHO cells expressing mGluR1α (IC50 = 120 μM); has agonist activity at mGluR2, inducing long-term depression in rat hippocampal dentate gyrus, an effect that can be blocked by an mGluR2 antagonist; blocks long-term potentiation in the CA1 region