Department of Psychiatry and Psychotherapy, Technische Universität Dresden, Dresden, Germany.
Brain Res. 2012 Oct 10;1478:36-47. doi: 10.1016/j.brainres.2012.08.034. Epub 2012 Aug 25.
Several studies report differences between adults and adolescents in reward processing and impulsivity. Consistently, adolescents are more impulsive in their decision making, as measured by intertemporal choice tasks. Since impulsivity affects an individual's perception and neural processing of rewards, it is unclear whether previously reported differences in brain activation between adults and adolescents are primarily due to maturation of the brain reward system or differences in impulsivity (i.e. discounting behaviour). To disentangle this, we analysed data from 235 adolescents and 29 adults who performed an intertemporal choice task in which monetary rewards were adapted to individual impulsivity. Using functional magnetic resonance imaging (fMRI), we measured brain activity and assessed impulsivity and consistency of choices at the behavioural level. Although adolescents discounted delayed rewards more steeply than adults, when controlling for impulsivity, neural processing of reward value did not differ between groups. However, more impulsive subjects showed a lower brain response to delayed rewards, independent of age. Concerning decision making, adolescents exhibited a lower consistency of choices and less brain activity in the parietal network than adults. We conclude that processing of the value of prospective delayed rewards is more sensitive to discounting behaviour than to chronological age. Lower consistency of intertemporal choices might indicate ongoing maturation of parietal brain areas in adolescents.
几项研究报告称，成年人和青少年在奖励处理和冲动性方面存在差异。一致的是，青少年在他们的决策中更冲动，如跨期选择任务所测量的。由于冲动性影响个体对奖励的感知和神经处理，因此尚不清楚之前报告的成年人和青少年之间大脑激活的差异主要是由于大脑奖励系统的成熟还是冲动性的差异（即折扣行为）。为了理清这一点，我们分析了 235 名青少年和 29 名成年人的数据，他们在一个跨期选择任务中表现出金钱奖励根据个体冲动性进行调整。使用功能磁共振成像（fMRI），我们测量了大脑活动，并在行为水平上评估了冲动性和选择的一致性。尽管青少年比成年人更陡峭地折现延迟奖励，但在控制冲动性时，两组之间的奖励价值的神经处理没有差异。然而，更冲动的受试者对延迟奖励的大脑反应较低，与年龄无关。关于决策，与成年人相比，青少年在选择时的一致性较低，顶叶网络的大脑活动也较少。我们的结论是，对未来延迟奖励的价值处理比对折扣行为更敏感。跨期选择的一致性较低可能表明青少年顶叶大脑区域的发育仍在继续。
