Palmatier Matthew I, Liu Xiu, Matteson Gina L, Donny Eric C, Caggiula Anthony R, Sved Alan F
Department of Psychology, University of Pittsburgh, 3137 Sennott Square, Pittsburgh, PA 15260, USA.
Psychopharmacology (Berl). 2007 Dec;195(2):235-43. doi: 10.1007/s00213-007-0897-6. Epub 2007 Aug 5.
Nicotine is widely assumed to convey reinforcing properties upon tobacco-related stimuli through associative learning. We have proposed that the reinforcement derived from these conditional stimuli can be inflated by a nonassociative "reinforcement-enhancing" effect of nicotine.
Experiment 1 investigated whether nicotine could establish a stimulus as a conditioned reinforcer. Using the same subjects, Experiment 2 examined whether responding for a nicotine-associated stimulus was enhanced by response-independent administration of nicotine.
Self-administered nicotine (Paired group, 0.03 mg kg(1) infusion(-1)) or saline (conditional stimulus or CS-Only group) was paired with a stimulus light (CS). An Unpaired group, yoked to the Paired group, received equal exposure to nicotine and the CS, but each event was temporally separated. To test for conditioning, the CS was then made contingent upon a novel lever-pressing response. In Experiment 2, a subset of the paired rats (self-administering) continued to lever press while receiving contingent nicotine and the CS. To determine whether nicotine enhanced responding for the CS, two remaining subsets of the Paired group responded for the CS while receiving nicotine (YNIC) or saline (YSAL) yoked to the self-administering rats. All remaining control groups received response-contingent CS presentations, together with yoked nicotine or saline.
Pairing self-administered nicotine with the CS promoted the acquisition of a novel response for the CS. In Experiment 2, the Paired YNIC group responded at higher rates than control groups receiving YNIC or YSAL.
Nicotine can establish stimuli as conditioned reinforcers for which noncontingent nicotine can enhance responding.
人们普遍认为尼古丁通过联想学习赋予与烟草相关的刺激以强化特性。我们提出，来自这些条件刺激的强化作用可因尼古丁的非联想性“强化增强”效应而增强。
实验1研究尼古丁是否能将一种刺激确立为条件性强化物。使用相同的实验对象，实验2检验了与尼古丁相关的刺激的反应是否会因非反应性给予尼古丁而增强。
自我给药尼古丁（配对组，0.03毫克/千克输注量）或生理盐水（条件刺激组或仅CS组）与刺激光（CS）配对。一个非配对组与配对组相连，接受等量的尼古丁和CS暴露，但每个事件在时间上是分开的。为了测试条件作用，然后使CS取决于一种新的杠杆按压反应。在实验2中，配对大鼠的一个子集（自我给药）在接受条件性尼古丁和CS时继续进行杠杆按压。为了确定尼古丁是否增强了对CS的反应，配对组的另外两个子集在接受与自我给药大鼠相连的尼古丁（YNIC）或生理盐水（YSAL）时对CS做出反应。所有其余对照组接受反应性CS呈现，以及相连的尼古丁或生理盐水。
将自我给药的尼古丁与CS配对促进了对CS新反应的习得。在实验2中，配对的YNIC组的反应率高于接受YNIC或YSAL的对照组。
尼古丁可以将刺激确立为条件性强化物，对于这些强化物，非条件性尼古丁可以增强反应。
