Department of Psychological and Brain Sciences, Washington University, St. Louis, MO, USA.
Cogn Affect Behav Neurosci. 2018 Oct;18(5):982-999. doi: 10.3758/s13415-018-0617-1.
The capability to remember and execute intentions in the future - termed prospective memory (PM) - may be of special significance for older adults to enable successful completion of important activities of daily living. Despite the importance of this cognitive function, mixed findings have been obtained regarding age-related decline in PM, and, currently, there is limited understanding of potential contributing mechanisms. In the current study, older (N=41) and younger adults (N=47) underwent task-functional MRI during performance of PM conditions that encouraged either spontaneous retrieval (Focal) or sustained attentional monitoring (Non-focal) to detect PM targets. Older adults exhibited a reduction in PM-related sustained activity within the anterior prefrontal cortex (aPFC) and associated dorsal frontoparietal cognitive control network, due to an increase in non-specific sustained activation in (no-PM) control blocks (i.e., an age-related compensatory shift). Transient PM-trial specific activity was observed in both age groups within a ventral parietal memory network that included the precuneus. However, within a left posterior inferior parietal node of this network, transient PM-related activity was selectively reduced in older adults during the non-focal condition. These age differences in sustained and transient brain activity statistically mediated age-related declines in PM performance, and were potentially linked via age-related changes in functional connectivity between the aPFC and precuneus. Together, they support an account consistent with the Dual Mechanisms of Control framework, in which age-related PM declines are due to neural mechanisms that support proactive cognitive control processes, such as sustained attentional monitoring, while leaving reactive control mechanisms relatively spared.
未来记忆和执行意图的能力——即前瞻性记忆（PM）——对于老年人成功完成日常生活中的重要活动可能具有特殊意义。尽管这种认知功能很重要，但关于 PM 随年龄增长而下降的研究结果存在差异，目前对于潜在的促成机制还知之甚少。在当前的研究中，老年人（N=41）和年轻人（N=47）在执行 PM 条件时接受了任务功能磁共振成像，这些条件鼓励自发检索（聚焦）或持续注意力监测（非聚焦）以检测 PM 目标。老年人在前额皮质（aPFC）和相关的背侧额顶叶认知控制网络中表现出 PM 相关持续活动减少，这是由于（无-PM）对照块中非特异性持续激活增加所致（即与年龄相关的补偿性转变）。在腹侧顶叶记忆网络中，两组年龄组都观察到短暂的 PM 试验特异性活动，包括楔前叶。然而，在该网络的左后下顶叶节点中，老年人在非聚焦条件下的短暂 PM 相关活动选择性减少。这些持续和瞬态脑活动的年龄差异在统计学上介导了 PM 表现随年龄的下降，并且可能通过 aPFC 和楔前叶之间的功能连接的年龄相关变化相关联。总的来说，它们支持与双机制控制框架一致的解释，即与年龄相关的 PM 下降是由于支持主动认知控制过程（如持续注意力监测）的神经机制所致，而反应性控制机制相对不受影响。
