Marshall-Goodell B, Gormezano I
Department of Psychology, University of Iowa, Iowa City, IA 52242.
Pharmacol Biochem Behav. 1991 Jun;39(2):503-7. doi: 10.1016/0091-3057(91)90216-o.
Two experiments were conducted to determine cocaine's (0, 1, 3, and 6 mg/kg) effects on associative, nonassociative, and motor processes in classical conditioning of the rabbit's nictitating membrane response (NMR). In Experiment 1, acquisition training consisted of tone- and light-conditioned stimuli (CSs) each paired on separate trials with a shock unconditioned stimulus (UCS). Cocaine injected prior to each session significantly impaired acquisition of conditioned responses (CRs). In Experiment 2, rabbits received cocaine injections prior to each training session involving explicitly unpaired CS-alone and UCS-alone presentations. Cocaine had no significant effects upon: base rate of NMRs; frequency of NMRs during presentations of the CSs; and frequency, amplitude, and latency of the UCRs. Consequently, cocaine's impairment of CR acquisition could not be attributed to its effects upon the nonassociative processes of base rate, sensitization, and pseudoconditioning, nor upon the sensory processing of the UCS and/or motor functioning of the UCR. Rather, cocaine's effects upon CR acquisition were mediated by the drug's effect upon associative processes. It appears likely that the drug affected the ability of the CS to enter into the associative conditioning process.
进行了两项实验，以确定可卡因（0、1、3和6毫克/千克）对兔瞬膜反应（NMR）经典条件反射中联想、非联想和运动过程的影响。在实验1中，习得训练包括音调条件刺激和光条件刺激（CSs），每次试验分别与电击非条件刺激（UCS）配对。每次训练前注射可卡因显著损害了条件反应（CRs）的习得。在实验2中，兔子在每次训练前接受可卡因注射，训练包括单独明确呈现未配对的CS和单独呈现UCS。可卡因对以下方面没有显著影响：NMR的基础率；CS呈现期间NMR的频率；以及UCR的频率、幅度和潜伏期。因此，可卡因对CR习得的损害不能归因于其对基础率、敏化和假性条件反射等非联想过程的影响，也不能归因于对UCS的感觉处理和/或UCR的运动功能的影响。相反，可卡因对CR习得的影响是由药物对联想过程的影响介导的。药物似乎影响了CS进入联想条件反射过程的能力。
