Institute of Cognitive Neuroscience, University College London, London, UK.
Nat Neurosci. 2013 May;16(5):648-53. doi: 10.1038/nn.3364. Epub 2013 Mar 24.
Senescence affects the ability to utilize information about the likelihood of rewards for optimal decision-making. Using functional magnetic resonance imaging in humans, we found that healthy older adults had an abnormal signature of expected value, resulting in an incomplete reward prediction error (RPE) signal in the nucleus accumbens, a brain region that receives rich input projections from substantia nigra/ventral tegmental area (SN/VTA) dopaminergic neurons. Structural connectivity between SN/VTA and striatum, measured by diffusion tensor imaging, was tightly coupled to inter-individual differences in the expression of this expected reward value signal. The dopamine precursor levodopa (L-DOPA) increased the task-based learning rate and task performance in some older adults to the level of young adults. This drug effect was linked to restoration of a canonical neural RPE. Our results identify a neurochemical signature underlying abnormal reward processing in older adults and indicate that this can be modulated by L-DOPA.
衰老是影响利用有关奖励可能性信息进行最优决策能力的一个因素。我们利用功能性磁共振成像技术在人类身上发现，健康的老年人存在预期价值的异常特征，导致伏隔核（大脑中接收来自黑质/腹侧被盖区多巴胺能神经元丰富输入投射的区域）中不完全的奖励预测误差（RPE）信号。通过扩散张量成像测量的黑质/腹侧被盖区与纹状体之间的结构连通性与该预期奖励价值信号的个体间差异表达紧密相关。多巴胺前体左旋多巴（L-DOPA）可增加一些老年人的基于任务的学习率和任务表现，使其达到年轻人的水平。这种药物作用与恢复规范的神经 RPE 有关。我们的研究结果确定了老年人异常奖励处理的神经化学特征，并表明该特征可通过 L-DOPA 进行调节。
