Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA.
Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Cogn Affect Behav Neurosci. 2019 Jun;19(3):415-434. doi: 10.3758/s13415-018-00678-9.
Despite dopamine's significant role in models of value-based decision-making and findings demonstrating loss of dopamine function in aging, evidence of systematic changes in decision-making over the life span remains elusive. Previous studies attempting to resolve the neural basis of age-related alteration in decision-making have typically focused on physical age, which can be a poor proxy for age-related effects on neural systems. There is growing appreciation that aging has heterogeneous effects on distinct components of the dopamine system within subject in addition to substantial variability between subjects. We propose that some of the conflicting findings in age-related effects on decision-making may be reconciled if we can observe the underlying dopamine components within individuals. This can be achieved by incorporating in vivo imaging techniques including positron emission tomography (PET) and neuromelanin-sensitive MR. Further, we discuss how affective factors may contribute to individual differences in decision-making performance among older adults. Specifically, we propose that age-related shifts in affective attention ("positivity effect") can, in some cases, counteract the impact of altered dopamine function on specific decision-making processes, contributing to variability in findings. In an effort to provide clarity to the field and advance productive hypothesis testing, we propose ways in which in vivo dopamine imaging can be leveraged to disambiguate dopaminergic influences on decision-making, and suggest strategies for assessing individual differences in the contribution of affective attentional focus.
尽管多巴胺在基于价值的决策模型中起着重要作用，并且有研究发现多巴胺功能在衰老过程中会丧失，但在整个生命周期中决策行为是否会发生系统性变化仍难以捉摸。之前试图确定与年龄相关的决策神经基础的研究通常集中在生理年龄上，而生理年龄并不能很好地反映神经系统与年龄相关的变化。越来越多的人认识到，衰老对个体多巴胺系统的不同组成部分有不同的影响，此外，不同个体之间也存在很大的差异。我们提出，如果我们能够观察到个体内部潜在的多巴胺成分，那么一些与年龄相关的决策行为变化的矛盾发现可能会得到调和。这可以通过结合正电子发射断层扫描 (PET) 和神经黑色素敏感磁共振等体内成像技术来实现。此外，我们还讨论了情感因素如何导致老年人在决策表现上的个体差异。具体来说，我们提出，与年龄相关的情感注意力变化（“积极性效应”）在某些情况下可以抵消多巴胺功能改变对特定决策过程的影响，从而导致研究结果的差异。为了阐明这一领域并推进富有成效的假设检验，我们提出了利用体内多巴胺成像来区分多巴胺对决策的影响的方法，并提出了评估情感注意力焦点个体差异的策略。
