Correction to: Neuropsychopharmacology (2015) 40, 259–267; doi:10.1038/npp.2014.261; published online 22 October 2014

On page 262 (first paragraph under ‘Ketamine’s Abuse Liability: Mu Opioid Receptor Effects’), the references to lambda opioid receptors and lambda antagonists should have been to delta opioid receptors and delta antagonists. The same error appears on page 264 (second paragraph under ‘Novel Drug Development’).