The neurobiology of human reinforcement learning throughout the lifespan

描述（由申请人提供）：拟议的项目研究人类强化学习的神经机制。灵长类动物的电生理记录表明，多巴胺神经元编码强化学习模型所需的奖励预测误差（RPE）信号。然而，很少有来自人类的证据支持这一结论。拟议的项目使用临床和神经影像学方法相结合，研究强化学习中与年龄相关的变化的神经相关性。我们的具体目标如下：1）确定年轻和老年受试者的选择行为在多大程度上与动物强化学习模型在动态强化时间表任务中的预测相匹配，并确定强化学习中任何与年龄相关的变化，这些变化可能源于正常的与年龄相关的多巴胺神经元数量下降。2)为了确定患有帕金森病的老年受试者的强化学习，多巴胺神经元数量严重减少，是否受到疾病的影响并受到多巴胺能药物的调节。这一发现将为多巴胺是人类强化学习的基础提供因果证据。3)确定通过功能性MRI测量的多巴胺区域的活动是否与编码RPE信号的区域一致，并观察整个生命周期中强化学习变量的行为和神经估计是否在所有年龄段都一致。我们希望找到多巴胺编码人类RPE信号的相关和因果证据，并希望通过多巴胺水平的变化来解释整个生命周期中强化学习的差异。

DESCRIPTION (provided by applicant): The proposed project investigates the neural mechanisms underlying human reinforcement learning. Electrophysiological recordings from primates suggest that dopamine neurons encode a reward prediction error (RPE) signal required by reinforcement learning models. There is, however, scant evidence from humans supporting this conclusion. The proposed project uses a combination of clinical and neuroimaging approaches to study the neural correlates of age-related changes in reinforcement learning. Our specific aims are as follows: 1) To determine to what extent the choice behavior of young and elderly subjects matches the predictions of animal reinforcement learning models in a task with a dynamic reinforcement schedule and to identify any age-related changes in reinforcement learning that might stem from normal age-related decline in the number of dopamine neurons. 2) To determine if reinforcement learning in elderly subjects that suffer from Parkinson's disease, an atypically severe reduction in the number of dopamine neurons, is affected by the disease and modulated by dopaminergic medication. This finding would provide causal evidence that dopamine underlies human reinforcement learning. 3) To determine if activity in dopamine areas measured by functional MRI is consistent with those areas encoding a RPE signal and to see if behavioral and neural estimates of reinforcement learning variables throughout the lifespan match consistently at all ages. We hope to find correlative and causal evidence for dopamine encoding the RPE signal in humans and hope to account for differences in reinforcement learning across the lifespan by changes in dopamine levels.