Chang Stephen E, McDannald Michael A, Wheeler Daniel S, Holland Peter C
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA.
Behav Neurosci. 2012 Apr;126(2):279-89. doi: 10.1037/a0027576.
Prior reinforcement of a neutral stimulus often blocks subsequent conditioning of a new stimulus if a compound of the original and new cues is paired with the same reinforcer. However, if the value of the reinforcer is altered when the compound is presented, the new cue typically acquires conditioning, a result called unblocking. Blocking, unblocking, and related phenomena have been attributed to variations in processing of either the reinforcer, for example, the Rescorla-Wagner (1972) model, or cues, for example, the Pearce-Hall (1980) model. Here, we examined the effects of lesions of the basolateral amygdala on the occurrence of unblocking when the food reinforcer was increased in quantity at the time of introduction of the new cue. The lesions had no effects on unblocking in a simple design (Experiment 1), which did not distinguish between unblocking produced by variations in reward or cue processing. However, in a procedure that distinguished between unblocking due to direct conditioning by the added reinforcer, consistent with the Rescorla-Wagner (1972) model, and that due to increases in conditioning to the original reinforcer, consistent with the Pearce-Hall (1980) and other models of learning, the lesions prevented unblocking of the latter type. These results were discussed in the context of roles of the basolateral amygdala in coding and using reward prediction error information in associative learning.
如果将原来的线索与新线索组成的复合物与同一个强化物配对，那么对中性刺激的先前强化往往会阻碍随后对新刺激的条件作用。然而，如果在呈现复合物时改变强化物的价值，新线索通常会获得条件作用，这一结果称为解除阻断。阻断、解除阻断及相关现象被归因于强化物加工过程的变化，例如雷斯克拉-瓦格纳（1972）模型，或线索加工过程的变化，例如皮尔斯-霍尔（1980）模型。在此，我们研究了基底外侧杏仁核损伤对在引入新线索时增加食物强化物数量情况下解除阻断发生的影响。在一个简单设计（实验1）中，损伤对解除阻断没有影响，该设计没有区分由奖励或线索加工变化产生的解除阻断。然而，在一个区分由添加的强化物直接产生的条件作用导致的解除阻断（与雷斯克拉-瓦格纳（1972）模型一致）和由对原来强化物的条件作用增加导致的解除阻断（与皮尔斯-霍尔（1980）及其他学习模型一致）的程序中，损伤阻止了后一种类型的解除阻断。这些结果在基底外侧杏仁核在联想学习中编码和使用奖励预测误差信息的作用背景下进行了讨论。
