Beck S G, O'Brien J H
Exp Neurol. 1983 Sep;81(3):528-41. doi: 10.1016/0014-4886(83)90324-2.
A classical conditioning experiment was designed to determine if a conditioned neural response would develop and persist in cortical evoked potentials elicited by a foreleg stimulus (CS+) that was paired with morphine administration during the development of dependence and subsequent withdrawal. A stimulus to the other foreleg (CS-) was presented explicitly unpaired with morphine delivery. After dependence was established, the rats were taken from the experimental chamber and withdrawn from morphine for 6 days in their home cages. Finally, during the testing phase, the animals were returned to the experimental chamber and the foreleg stimuli were presented. The CS+ was paired with either morphine or saline injections. Changes due to both morphine effects only and conditioning were observed. The conditioned response, however, was present only in the cortical evoked potentials recorded from those animals receiving contralateral foreleg stimulation as the CS+. The conditioned neural response persisted after withdrawal and was present in both the drug-free and morphine-intoxicated animals. These results provide support for the relapse theory that a nonextinguished conditioned response is retained after withdrawal. However, further experiments are necessary to determine if these conditioned responses can elicit drug-seeking behavior.
设计了一项经典条件反射实验，以确定在依赖形成及随后戒断过程中，与吗啡给药配对的前肢刺激（条件刺激+）所诱发的皮层诱发电位中，是否会形成并持续存在条件性神经反应。明确呈现对另一只前肢的刺激（条件刺激-），且该刺激与吗啡给药不配对。在建立依赖后，将大鼠从实验箱中取出，在其饲养笼中进行6天的吗啡戒断。最后，在测试阶段，将动物放回实验箱并施加前肢刺激。条件刺激+与吗啡注射或生理盐水注射配对。观察到了仅由吗啡效应以及条件反射所引起的变化。然而，条件反应仅出现在那些接受对侧前肢刺激作为条件刺激+的动物所记录的皮层诱发电位中。条件性神经反应在戒断后持续存在，且在未用药和吗啡中毒的动物中均有出现。这些结果为戒断后未消退的条件反应会被保留这一复发理论提供了支持。然而，还需要进一步的实验来确定这些条件反应是否能引发觅药行为。
