ω-Conotoxin GVIA is a peptide neurotoxin first isolated from the marine snail Conus geographus L. It selectively and reversibly blocks specific voltage-dependent N-type Ca2+ channels in neurons, but not in muscle. It reduces (RS)-3,5-DHPG2-induced long term depression in vivo. It does not bind to either the dihydropyridine or verapamil binding sites. It is used as a powerful probe for exploring the vertebrate pre-synaptic terminal.