Burns L H, Everitt B J, Robbins T W
Neurex, Menlo Park, California 94025-1012, USA.
Behav Brain Res. 1999 Apr;100(1-2):123-33. doi: 10.1016/s0166-4328(98)00119-3.
Rats with excitotoxic lesions of the basolateral amygdala (BLA) were not impaired in the acquisition of an appetitive visuospatial conditional discrimination between stimuli varying in temporal frequency that has previously been shown to be sensitive to the effects of lesions of the striatum and cingulate cortex. After asymptotic performance was attained, discrimination was reinforced according to a fixed ratio (FR) schedule under which n presentations of sucrose were provided following n correct responses; each correct response also being reinforced immediately by a light acting as a conditioned reinforcer. Under these conditions of reinforcement when FRn=5, BLA-lesioned rats initially showed transient impairments in several aspects of performance, but rapidly attained control levels over subsequent test sessions. No further impairments occurred when FRn=10/20. However, in various conditions of extinction, further differences in performance were revealed between the BLA-lesioned and control groups, notably a significantly enhanced resistance to extinction when both sucrose and conditioned reinforcement were omitted. The results are discussed in terms of limbic-striatal mechanisms in the control of discrimination learning and the possible role of the amygdala in the mediation of different aspects of conditioned reinforcement.
基底外侧杏仁核（BLA）发生兴奋性毒性损伤的大鼠，在习得一种基于时间频率变化的视觉空间条件性辨别任务时并未受损，此前研究表明该任务对纹状体和扣带回皮质损伤的影响较为敏感。在达到渐近表现后，根据固定比率（FR）时间表强化辨别任务，即每做出n次正确反应后提供n次蔗糖；每次正确反应还会立即由一个作为条件强化物的光予以强化。在FRn = 5的这种强化条件下，BLA损伤的大鼠最初在表现的几个方面出现短暂损伤，但在随后的测试阶段迅速达到对照水平。当FRn = 10/20时，未出现进一步损伤。然而，在各种消退条件下，BLA损伤组和对照组之间在表现上出现了进一步差异，特别是当蔗糖和条件强化物都被省略时，对消退的抵抗力显著增强。本文从边缘 - 纹状体机制对辨别学习的控制以及杏仁核在条件强化不同方面的介导作用的可能角色对结果进行了讨论。
