Grady C L, McIntosh A R, Bookstein F, Horwitz B, Rapoport S I, Haxby J V
Baycrest Centre for Geriatric Care, Rotman Research Institute, Toronto, Ontario, Canada.
Neuroimage. 1998 Nov;8(4):409-25. doi: 10.1006/nimg.1998.0376.
Young and old adults underwent positron emission tomography during the performance of a working memory task for faces (delayed match-to-sample), in which the delay between the sample and choice faces was varied from 1 to 21 s. Reaction time was slower and accuracy lower in the old group, but not markedly so. Values of regional cerebral blood flow (rCBF) were analyzed for sustained activity across delay conditions, as well as for changes as delay increased. Many brain regions showed similar activity during these tasks in both young and old adults, including left anterior prefrontal cortex, which had increased rCBF with delay, and ventral extrastriate cortex, which showed decreased rCBF with delay. However, old adults had less activation overall and less modulation of rCBF across delay in right ventrolateral prefrontal cortex than did the young adults. Old adults also showed greater rCBF activation in left dorsolateral prefrontal cortex across all WM delays and increased rCBF at short delays in left occipitoparietal cortex compared to young adults. Activity in many of these regions was differentially related to performance in that it was associated with decreasing response times in the young group and increasing response times in the older individuals. Thus despite the finding that performance on these memory tasks and associated activity in a number of brain areas are relatively preserved in old adults, differences elsewhere in the brain suggest that different strategies or cognitive processes are used by the elderly to maintain memory representations over short periods of time.
年轻和年长成年人在执行一项面部工作记忆任务（延迟匹配样本）时接受了正电子发射断层扫描，其中样本脸和选择脸之间的延迟从1秒到21秒不等。老年组的反应时间较慢，准确率较低，但差异并不显著。分析了区域脑血流量（rCBF）在不同延迟条件下的持续活动情况，以及随着延迟增加的变化情况。在这些任务中，年轻和年长成年人的许多脑区都表现出相似的活动，包括左侧前额叶皮层，其rCBF随延迟增加，以及腹侧纹外皮层，其rCBF随延迟减少。然而，与年轻成年人相比，年长成年人在右侧腹外侧前额叶皮层的整体激活较少，且rCBF在延迟期间的调节也较少。与年轻成年人相比，年长成年人在所有工作记忆延迟期间左侧背外侧前额叶皮层的rCBF激活程度更高，并且在左侧枕顶叶皮层短延迟时rCBF增加。这些区域中的许多区域的活动与表现存在差异相关，因为它与年轻组中反应时间的减少以及年长者中反应时间的增加有关。因此，尽管发现在这些记忆任务上的表现以及许多脑区中的相关活动在年长成年人中相对得以保留，但大脑其他部位的差异表明，老年人在短时间内使用了不同的策略或认知过程来维持记忆表征。
