title: Extinction of conditioned responses in abstinent cocaine or opioid users.
mesh_terms: D000328:Adult; D003042:Cocaine; D003213:Conditioning, Psychological; D005108:Extinction, Psychological; D006801:Humans; D008297:Male; D009293:Opioid-Related Disorders / Q000534:rehabilitation*; D011897:Random Allocation; D013375:Substance Withdrawal Syndrome / Q000209:etiology / Q000628:therapy; D019966:Substance-Related Disorders / Q000534:rehabilitation*
chemical_list: D003042:Cocaine