McDougall Sanders A, Pothier Alexandria G, Der-Ghazarian Taleen, Herbert Matthew S, Kozanian Olga O, Castellanos Kevin A, Flores Ana T
Department of Psychology, California State University, 5500 University Parkway, San Bernardino, CA 92407, USA.
Behav Pharmacol. 2011 Oct;22(7):693-702. doi: 10.1097/FBP.0b013e32834affb2.
During adulthood, associative learning is necessary for the expression of one-trial behavioral sensitization; however, it is uncertain whether the same associative processes are operative during the preweanling period. Two strategies were used to assess the importance of associative learning for one-trial behavioral sensitization of preweanling rats. In the initial experiments, we varied both the sequence and time interval between presentation of the conditioned stimulus (CS, novel environment) and unconditioned stimulus (US, cocaine). In the final experiment, we determined whether electroconvulsive shock-induced retrograde amnesia would disrupt one-trial behavioral sensitization. Results showed that robust-sensitized responding was apparent regardless of the sequence in which cocaine and the novel environment (the presumptive CS) were presented. Varying the time between CS and US presentation (0, 3, or 6 h) was also without effect. Results from experiment 3 showed that single or multiple electroconvulsive shock treatments did not alter the expression of the sensitized response. Therefore, these data indicated that one-trial behavioral sensitization of preweanling rats was exclusively mediated by nonassociative mechanisms and that associative processes did not modulate sensitized responding. These findings are in contrast to what is observed during adulthood, as adult rats exhibit one-trial behavioral sensitization only when associative processes are operative.
在成年期，联想学习对于单次试验行为敏化的表现是必要的；然而，尚不确定在断奶前阶段是否存在相同的联想过程。采用了两种策略来评估联想学习对断奶前大鼠单次试验行为敏化的重要性。在最初的实验中，我们改变了条件刺激（CS，新环境）和非条件刺激（US，可卡因）呈现之间的顺序和时间间隔。在最后的实验中，我们确定电惊厥休克诱导的逆行性遗忘是否会破坏单次试验行为敏化。结果表明，无论可卡因和新环境（假定的CS）呈现的顺序如何，强烈的敏化反应都很明显。改变CS和US呈现之间的时间（0、3或6小时）也没有效果。实验3的结果表明，单次或多次电惊厥休克治疗并未改变敏化反应的表现。因此，这些数据表明，断奶前大鼠的单次试验行为敏化完全由非联想机制介导，并且联想过程不会调节敏化反应。这些发现与成年期观察到的情况形成对比，因为成年大鼠仅在联想过程起作用时才表现出单次试验行为敏化。
