Conditioned reinforcement in rats established with self-administered nicotine and enhanced by noncontingent nicotine.
Palmatier MI, Liu X, Matteson GL, Donny EC, Caggiula AR, Sved AF. Conditioned reinforcement in rats established with self-administered nicotine and enhanced by noncontingent nicotine. Psychopharmacology (Berl). 2007 Dec; 195(2):235-43.