Sasse Laura K, Peters Jan, Büchel Christian, Brassen Stefanie
Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Hum Brain Mapp. 2015 Oct;36(10):4210-21. doi: 10.1002/hbm.22912. Epub 2015 Jul 28.
Imagining future events while performing an intertemporal choice task can attenuate the devaluation of future rewards. Here, we investigated whether this effect and its neural basis depend on the degree of personal prior experience associated with the simulated future scenarios. Functional magnetic resonance imaging was combined with a modified intertemporal choice task in which the delayed options were either purely monetary, or linked with a social event. Subject-specific events differed regarding familiarity, that is, meeting a close, familiar person or a celebrity in a café. In line with recent hypotheses on episodic construction, the simulation of future familiar and unfamiliar events equally attenuated delay discounting behavior in comparison with the control condition and both were imagined with similar richness. Imaging data, however, indicate that these results rely on differential neural activation patterns. The hippocampus was particularly involved in the simulation of unfamiliar future scenarios, probably reflecting enhanced construction processes when personal experience with similar past events is lacking. Consequently, functional coupling of the hippocampus with neural valuation signals in the anterior cingulate cortex predicted the subjective value only of rewards offered in the unfamiliar context. In contrast, valuation of rewards in a familiar context was predicted by activation in key nodes of emotional and autobiographical memory retrieval and dynamically modulated by frontal-striatal connectivity. The present data emphasize that the mechanisms underlying neural valuation of prospective rewards largely depend on the pre-experience with the context in which they are offered.
在执行跨期选择任务时想象未来事件可以减弱未来奖励的贬值。在此，我们研究了这种效应及其神经基础是否取决于与模拟未来情景相关的个人先前经验的程度。功能磁共振成像与一项修改后的跨期选择任务相结合，在该任务中，延迟选项要么是纯粹的金钱奖励，要么与一个社交事件相关联。特定于个体的事件在熟悉程度上有所不同，即在咖啡馆遇到一个亲密、熟悉的人或一位名人。与最近关于情景构建的假设一致，与对照条件相比，对未来熟悉和不熟悉事件的模拟同样减弱了延迟折扣行为，并且两者都以相似的丰富程度进行想象。然而，成像数据表明这些结果依赖于不同的神经激活模式。海马体特别参与了对不熟悉未来情景的模拟，这可能反映了在缺乏与类似过去事件的个人经验时增强的构建过程。因此，海马体与前扣带回皮质中的神经估值信号的功能耦合仅预测了在不熟悉情境中提供的奖励的主观价值。相反，熟悉情境中奖励的估值由情感和自传体记忆检索的关键节点的激活预测，并由额叶 - 纹状体连接动态调节。目前的数据强调，预期奖励的神经估值背后的机制很大程度上取决于对其提供情境的先前经验。
