Goldberg S R, Spealman R D, Goldberg D M
Science. 1981 Oct 30;214(4520):573-5. doi: 10.1126/science.7291998.
Squirrel monkeys pressed a level at high rates under a second-order schedule of reinforcement in which level pressing produced a brief visual stimulus that was occasionally contiguous with an intravenous injection of nicotine. The rate of lever pressing could be markedly reduced either by substituting saline for nicotine injections or by blocking the effects of nicotine with mecamylamine. The rate of level pressing could be reduced by eliminating the brief visual stimulus. These results show that nicotine can function as an effective reinforcer under a second-order schedule of drug self-administration and that an environmental stimulus associated with nicotine intake can contribute to the maintenance of persistent drug-seeking behavior.
松鼠猴在二级强化程序下以高频率按压杠杆，在该程序中，按压杠杆会产生短暂的视觉刺激，这种刺激偶尔会与静脉注射尼古丁同时出现。用生理盐水替代尼古丁注射或用美加明阻断尼古丁的作用，均可显著降低杠杆按压频率。消除短暂的视觉刺激也可降低杠杆按压频率。这些结果表明，在药物自我给药的二级程序下，尼古丁可作为一种有效的强化物，且与尼古丁摄入相关的环境刺激可有助于维持持续的觅药行为。
