School of Psychology, University of New South Wales, Sydney, New South Wales 2052, Australia.
Learn Mem. 2010 Feb 13;17(2):71-5. doi: 10.1101/lm.1668310. Print 2010 Feb.
Three experiments used rats to investigate the role of dopamine activity in learning to inhibit conditioned fear responses (freezing) in extinction. In Experiment 1, rats systemically injected with the D2 dopamine antagonist, haloperidol, froze more across multiple extinction sessions and on a drug-free retention test than control rats. In Experiment 2, rats extinguished under an intracerebroventricular (ICV) infusion of haloperidol suppressed fear responses across extinction but froze more on a subsequent drug-free retention test than control rats. In Experiment 3, rats extinguished under an infusion of haloperidol in the nucleus accumbens were impaired in suppressing fear responses across extinction and froze more on subsequent drug-free retention test than control rats. These results show that learning to inhibit fear responses in extinction requires dopamine activity in the nucleus accumbens. They were interpreted to mean that dopaminergic activity in the nucleus accumbens regulates the prediction error required for learning to inhibit fear responses in extinction.
三项实验使用大鼠来探究多巴胺活动在学习抑制条件性恐惧反应（冻结）的消退中的作用。在实验 1 中，与对照组大鼠相比，系统注射 D2 多巴胺拮抗剂氟哌啶醇的大鼠在多次消退过程中以及在无药物保留测试中冻结的次数更多。在实验 2 中，在脑室内（ICV）输注氟哌啶醇的大鼠在消退过程中抑制了恐惧反应，但与对照组大鼠相比，在随后的无药物保留测试中冻结的次数更多。在实验 3 中，在伏隔核中输注氟哌啶醇的大鼠在消退过程中抑制恐惧反应的能力受损，并且在随后的无药物保留测试中冻结的次数比对照组大鼠更多。这些结果表明，在消退中学习抑制恐惧反应需要伏隔核中的多巴胺活动。这些结果被解释为意味着伏隔核中的多巴胺活性调节了在消退中学习抑制恐惧反应所需的预测误差。
