title: Intragastric morphine infusion as a reinforcement for instrumental reflex [proceedings].
mesh_terms: D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology*; D007441:Intubation, Gastrointestinal; D008297:Male; D009020:Morphine / Q000008:administration & dosage*; D051381:Rats; D012054:Reinforcement, Psychology
chemical_list: D009020:Morphine