Johnson Alexander W, Gallagher Michela, Holland Peter C
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA.
J Neurosci. 2009 Jan 21;29(3):696-704. doi: 10.1523/JNEUROSCI.3758-08.2009.
Considerable evidence implicates the basolateral amygdala (BLA) in the formation of outcome representations that link cues to the incentive properties of reinforcers. Animals with BLA damage show impaired performance in reinforcer devaluation tasks, in which the value of the food reinforcer is reduced by satiation or food-toxin pairings after the completion of cue or response training. Although intact animals spontaneously reduce their conditioned responding after such reinforcer devaluation procedures, animals with BLA lesions made before training typically do not, as evidenced across a range of species, training contingencies, and devaluation procedures. In contrast, the role of the BLA in devaluation task performance once such outcome representations are established is unclear. Whereas Pickens et al. (2003) found normal devaluation performance in rats when BLA lesions were made after pavlovian light-food pairings but before devaluation by food-toxin pairings, Ostlund and Balleine (2008) found impaired devaluation performance when BLA lesions were made after instrumental training with multiple instrumental responses and food reinforcers but before devaluation of one reinforcer by selective satiation. Those studies differed in their use of pavlovian or operant training contingencies, single or multiple reinforcers, and associative or motivational devaluation procedures. Here we found that, when multiple reinforcers were used, posttraining BLA lesions disrupted the expression of devaluation performance in rats, using either pavlovian or instrumental training procedures and either conditioned taste aversion or satiation devaluation procedures. Thus, BLA apparently plays a critical role in maintaining or using sensory associations of reinforcer value when multiple outcomes must be coded but not under single-outcome conditions.
大量证据表明，基底外侧杏仁核（BLA）在将线索与强化物的激励属性相联系的结果表征形成过程中发挥作用。患有BLA损伤的动物在强化物贬值任务中表现受损，在这种任务中，食物强化物的价值在线索或反应训练完成后通过饱腹感或食物与毒素配对而降低。尽管完整的动物在这种强化物贬值程序后会自发地减少其条件反应，但训练前出现BLA损伤的动物通常不会，这在一系列物种、训练意外情况和贬值程序中都得到了证明。相比之下，一旦建立了这样的结果表征，BLA在贬值任务表现中的作用尚不清楚。虽然皮肯斯等人（2003年）发现，在巴甫洛夫式光与食物配对后但在食物与毒素配对导致贬值之前对大鼠进行BLA损伤时，大鼠的贬值表现正常，但奥斯特伦德和巴莱内（2008年）发现，在使用多种工具反应和食物强化物进行工具训练后但在通过选择性饱腹感使一种强化物贬值之前对大鼠进行BLA损伤时，大鼠的贬值表现受损。这些研究在巴甫洛夫式或操作性训练意外情况、单一或多种强化物以及联想或动机性贬值程序的使用上存在差异。在这里我们发现，当使用多种强化物时，训练后进行BLA损伤会破坏大鼠的贬值表现，无论使用巴甫洛夫式还是工具性训练程序，以及条件性味觉厌恶或饱腹感贬值程序。因此，当必须编码多种结果时，BLA显然在维持或利用强化物价值的感觉关联方面起着关键作用，但在单一结果条件下则不然。
