Grady Cheryl L, Yu He, Alain Claude
Rotman Research Institute at Baycrest, University of Toronto, Toronto, Ontario, Canada.
Cereb Cortex. 2008 Jan;18(1):189-99. doi: 10.1093/cercor/bhm045. Epub 2007 May 10.
We used functional magnetic resonance imaging and a 1-back task to assess working memory (WM) for spatial (sound location) and nonspatial (sound category) auditory information in younger and older adults. A mixed block-event-related design was used to measure sustained activity during each task block and transient activity to targets (repetitions of location or category). In both groups, there was increased sustained activity for category WM in left anterior temporal cortex and inferior prefrontal cortex (PFC) and increased activity for location WM in right inferior parietal cortex and dorsal PFC. There were no reliable age differences in this pattern of activity. Older adults had more sustained activity than younger adults in left PFC during both tasks, suggesting that additional PFC recruitment in older adults reflects nonspecific engagement of frontally mediated task-monitoring processes. Both groups showed lower transient than sustained activity in auditory cortex bilaterally; however, older adults showed smaller target-related reductions of activity during the category task. A greater reduction of activity to category targets in left auditory cortex was associated with better performance on this task in older adults, suggesting that a failure to modulate activity appropriately when a stimulus is repeated, or when a particular feature of the stimulus is repeated, could lead to reduced ability to detect this repetition.
我们使用功能磁共振成像和一项1-back任务，来评估年轻人和老年人对空间（声音位置）和非空间（声音类别）听觉信息的工作记忆（WM）。采用混合区组事件相关设计，来测量每个任务区组中的持续活动以及对目标（位置或类别的重复）的瞬态活动。在两组中，左前颞叶皮质和前额叶皮质（PFC）下部的类别WM持续活动增加，右顶下皮质和背侧PFC的位置WM活动增加。这种活动模式没有可靠的年龄差异。在两项任务中，老年人左PFC的持续活动均多于年轻人，这表明老年人额外的PFC募集反映了额叶介导的任务监测过程的非特异性参与。两组在双侧听觉皮质中的瞬态活动均低于持续活动；然而，老年人在类别任务中与目标相关的活动减少幅度较小。老年人左听觉皮质中对类别目标的活动减少幅度更大与该任务的更好表现相关，这表明当刺激重复时，或者当刺激的特定特征重复时，未能适当地调节活动，可能会导致检测这种重复的能力下降。
