Wellcome Trust Centre for Neuroimaging, University College London, London, WC1N 3BG, UK; Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA; Department of Psychology, University of Giessen, 35394 Giessen, Germany.
Neuropsychologia. 2013 Sep;51(11):2184-93. doi: 10.1016/j.neuropsychologia.2013.07.018. Epub 2013 Aug 1.
Previous studies have shown that appetitive motivation enhances episodic memory formation via a network including the substantia nigra/ventral tegmental area (SN/VTA), striatum and hippocampus. This functional magnetic resonance imaging (fMRI) study now contrasted the impact of aversive and appetitive motivation on episodic long-term memory. Cue pictures predicted monetary reward or punishment in alternating experimental blocks. One day later, episodic memory for the cue pictures was tested. We also investigated how the neural processing of appetitive and aversive motivation and episodic memory were modulated by dopaminergic mechanisms. To that end, participants were selected on the basis of their genotype for a variable number of tandem repeat polymorphism of the dopamine transporter (DAT) gene. The resulting groups were carefully matched for the 5-HTTLPR polymorphism of the serotonin transporter gene. Recognition memory for cues from both motivational categories was enhanced in participants homozygous for the 10-repeat allele of the DAT, the functional effects of which are not known yet, but not in heterozygous subjects. In comparison with heterozygous participants, 10-repeat homozygous participants also showed increased striatal activity for anticipation of motivational outcomes compared to neutral outcomes. In a subsequent memory analysis, encoding activity in striatum and hippocampus was found to be higher for later recognized items in 10-repeat homozygotes compared to 9/10-repeat heterozygotes. These findings suggest that processing of appetitive and aversive motivation in the human striatum involve the dopaminergic system and that dopamine plays a role in memory for both types of motivational information. In accordance with animal studies, these data support the idea that encoding of motivational events depends on dopaminergic processes in the hippocampus.
先前的研究表明，奖赏动机通过包括黑质/腹侧被盖区（SN/VTA）、纹状体和海马体在内的网络增强了情景记忆的形成。这项功能磁共振成像（fMRI）研究现在对比了厌恶和奖赏动机对情景长时记忆的影响。线索图片在交替的实验块中预测货币奖励或惩罚。一天后，测试了对线索图片的情景记忆。我们还研究了多巴胺能机制如何调节奖赏和厌恶动机以及情景记忆的神经加工。为此，根据多巴胺转运体（DAT）基因的可变串联重复多态性，选择参与者的基因型。然后将参与者分为多巴胺转运体基因（DAT）10 重复等位基因的纯合子组和杂合子组，两组参与者的 5-羟色胺转运体基因（5-HTTLPR）多态性匹配良好。多巴胺转运体（DAT）10 重复等位基因的纯合子组对两种动机类别线索的识别记忆增强，但其功能效应尚不清楚，但杂合子组没有。与杂合子参与者相比，10 重复纯合子参与者在预期动机结果（与中性结果相比）时，纹状体的活动也增加了。在随后的记忆分析中，发现与 9/10 重复杂合子相比，10 重复纯合子在纹状体和海马体的编码活动对于后来识别的项目更高。这些发现表明，人类纹状体中奖赏和厌恶动机的处理涉及多巴胺能系统，并且多巴胺在这两种类型的动机信息的记忆中发挥作用。与动物研究一致，这些数据支持这样一种观点，即动机事件的编码取决于海马体中的多巴胺能过程。
