Department of Psychological and Brain Sciences, 3400 North Charles Street, Baltimore, MD 21218, USA.
Neurobiol Learn Mem. 2012 May;97(4):441-51. doi: 10.1016/j.nlm.2012.03.008. Epub 2012 Mar 26.
Initially-neutral cues paired with rewards are thought to acquire motivational significance, as if the incentive motivational value of the reward is transferred to the cue. Such cues may serve as secondary reinforcers to establish new learning, modulate the performance of instrumental action (Pavlovian-instrumental transfer, PIT), and be the targets of approach and other cue-directed behaviors. Here we examined the effects of lesions of the ventral striatal nucleus accumbens (ACb) and the basolateral amygdala (BLA) on the acquisition of discriminative autoshaped lever-pressing in rats. Insertion of one lever into the experimental chamber was reinforced by sucrose delivery, but insertion of another lever was not reinforced. Although sucrose was delivered independently of the rats' behavior, sham-lesioned rats rapidly came to press the reinforced but not the nonreinforced lever. Bilateral ACb lesions impaired the initial acquisition of sign-tracking but not its terminal levels. In contrast, BLA lesions produced substantial deficits in terminal levels of sign-tracking. Furthermore, whereas ACb lesions primarily affected the probability of lever press responses, BLA lesions mostly affected the rate of responding once it occurred. Finally, disconnection lesions that disrupted communication between ACb and BLA produced both sets of deficits. We suggest that ACb is important for initial acquisition of consummatory-like responses that incorporate hedonic aspects of the reward, while BLA serves to enhance such incentive salience once it is acquired.
最初中性的线索与奖励配对后被认为获得了动机意义，就好像奖励的激励动机价值被转移到了线索上。这些线索可以作为二级强化物来建立新的学习，调节工具性操作的表现（条件性操作转移，PIT），并成为接近和其他线索引导行为的目标。在这里，我们研究了腹侧纹状体伏隔核（ACb）和基底外侧杏仁核（BLA）损伤对大鼠辨别性自动压杆行为习得的影响。将一根杠杆插入实验室会得到蔗糖的奖励，但插入另一根杠杆则不会得到奖励。尽管蔗糖的给予与大鼠的行为无关，但假手术组大鼠很快就会按压被强化的而不是未被强化的杠杆。双侧 ACb 损伤会损害标记追踪的初始获得，但不会损害其终末水平。相比之下，BLA 损伤会导致标记追踪的终末水平出现严重缺陷。此外，ACb 损伤主要影响压杆反应的概率，而 BLA 损伤主要影响反应一旦发生的速度。最后，破坏 ACb 和 BLA 之间通讯的离断性损伤同时产生了这两组缺陷。我们认为，ACb 对于包含奖励享乐方面的终末性消费样反应的初始获得很重要，而 BLA 则有助于增强这种激励显著性，一旦获得。
