Carranza-Jasso Rodrigo, Urcelay Gonzalo P, Nieto Javier, Sánchez-Carrasco Livia
División de Investigación y Posgrado, Facultad de Psicología, Universidad Nacional Autónoma de México, Mexico.
Department of Psychology, University of Cambridge, United Kingdom.
Behav Processes. 2014 Sep;107:47-60. doi: 10.1016/j.beproc.2014.07.014. Epub 2014 Aug 4.
Three experiments using rats in an appetitive conditioning procedure analyzed the effect of short and long (50s vs. 1440s) intertrial intervals (ITI) over the acquisition of conditioned stimulus (CS), context (Ctxt), and unconditioned stimulus (US) associations, as well as the effect on the extinction and renewal of the conditioned response to the CS. Experiment 1 revealed more contextual conditioned responses in groups trained with the short ITIs, however the renewal effect was not observed during test phase with either ITI condition. When subjects were pre-exposed to the contexts before the acquisition phase (Experiment 2) renewal of the conditioned response (CR) was only observed in long ITI group. However, when the acquisition context was extinguished (Experiment 3) the renewal effect observed in the Experiment 2 was weakened. In all three experiments subjects showed a similar number of responses to the tone predicting food, however they showed a clear contextual conditioning effect only for the groups trained with short ITIs. It is noteworthy that the acquisition context showed high levels of the CR in the renewal test only for groups trained with short ITIs (Experiment 2) but these responses were absent if additional contextual extinction was imposed before such test (Experiment 3). In general, all groups showed similar acquisition curves for the CS but only Short groups had an increase in the CR during the pre-CS. Also, context conditioning does not interfere with the conditioning of the CS and context pre-exposure prior to acquisition is essential in order to observe the renewal effect when long ITIs are used.
三项使用大鼠进行的、以奖赏性条件反射程序为基础的实验，分析了短（50秒）和长（1440秒）的试验间隔（ITI）对条件刺激（CS）、环境（Ctxt）和非条件刺激（US）关联习得的影响，以及对CS条件反应消退和恢复的影响。实验1显示，在短ITI训练的组中出现了更多的环境条件反应，然而，在任何一种ITI条件的测试阶段都未观察到恢复效应。当在习得阶段之前让实验对象预先接触环境（实验2）时，只有长ITI组观察到了条件反应（CR）的恢复。然而，当习得环境被消退时（实验3），实验2中观察到的恢复效应被削弱。在所有三项实验中，实验对象对预测食物的音调表现出相似数量的反应，然而，只有短ITI训练的组表现出明显的环境条件效应。值得注意的是，只有短ITI训练的组（实验2）在恢复测试中习得环境显示出高水平的CR，但如果在该测试之前施加额外的环境消退，则这些反应不存在（实验3）。总体而言，所有组对CS的习得曲线相似，但只有短ITI组在CS前出现了CR的增加。此外，环境条件作用不会干扰CS的条件作用，并且在使用长ITI时，习得前的环境预先接触对于观察恢复效应至关重要。
