Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, QC, Canada.
Neuropsychologia. 2010 Dec;48(14):4020-30. doi: 10.1016/j.neuropsychologia.2010.10.010. Epub 2010 Oct 12.
The ability to retrieve temporal and spatial context information from memory declines with healthy aging. The hippocampus (HC) has been shown to be associated with successful encoding and retrieval of spatio-temporal context, versus item recognition information (Davachi, Mitchell, & Wagner, 2003; Nadel, Samsonovich, Ryan, & Moscovitch, 2000; Ross & Slotnick, 2008). Aging has been linked to volume reduction in the HC (Bouchard, Malykhin, Martin, Hanstock, Emery, Fisher, & Camicioli, 2008; Malykhin, Bouchard, Camicioli, & Coupland, 2008; Raz et al., 2005). As such, age-associated reductions in anterior HC volume may contribute to the context memory deficits observed in older adults. In the current MRI study we investigated whether item recognition, spatial context and temporal context memory performance would be predicted by regional volumes in HC head (HH), body (HB) and tail (HT) volumes, using within group multiple regression analyses in a sample of 19 healthy young (mean age 24.3) and 20 older adults (mean age 67.7). We further examined between age-group differences in the volumes of the same HC sub-regions. Multiple regression analyses revealed that in younger adults both spatial and temporal context retrieval performance was predicted by anterior HC volume. Older age was associated with significant volume reductions in HH and HB, but not HT; and with reduced ability to retrieve spatial and temporal contextual details from episodic memory. However, HC volumes did not predict context retrieval performance in older adults. We conclude that individual differences in anterior, not posterior, HC volumes predict context memory performance in young adults. With age there may be a posterior-to-anterior shift from using HC-related processes, due to HC volume loss, to employing the prefrontal cortex to aid in the performance of cognitively demanding context memory tasks. However, due to concomitant changes in the prefrontal system with age, there are limits to compensation in the aging brain.
随着健康老龄化的发展，从记忆中检索时间和空间上下文信息的能力下降。研究表明，海马体（HC）与时空上下文的成功编码和检索有关，而与项目识别信息有关（Davachi、Mitchell 和 Wagner，2003；Nadel、Samsonovich、Ryan 和 Moscovitch，2000；Ross 和 Slotnick，2008）。随着年龄的增长，HC 的体积会减少（Bouchard、Malykhin、Martin、Hanstock、Emery、Fisher 和 Camicioli，2008；Malykhin、Bouchard、Camicioli 和 Coupland，2008；Raz 等人，2005）。因此，与年龄相关的 HC 前部体积减少可能导致老年人出现的上下文记忆缺陷。在当前的 MRI 研究中，我们通过对 19 名健康年轻人（平均年龄 24.3 岁）和 20 名老年人（平均年龄 67.7 岁）的组内多元回归分析，研究了 HC 头部（HH）、身体（HB）和尾部（HT）体积的区域体积是否可以预测项目识别、空间上下文和时间上下文记忆表现。我们进一步检查了相同 HC 亚区体积在不同年龄组之间的差异。多元回归分析表明，在年轻成年人中，空间和时间上下文的检索表现均与 HC 前部体积相关。年龄较大与 HH 和 HB 的体积显著减少有关，但与 HT 无关；并与从情节记忆中检索空间和时间上下文细节的能力降低有关。然而，HC 体积并不能预测老年人的上下文检索表现。我们的结论是，年轻人 HC 前部而非后部的体积差异预测了上下文记忆表现。随着年龄的增长，由于 HC 体积的减少，可能会从前部到后部转移，使用 HC 相关过程来辅助认知要求较高的上下文记忆任务的完成。然而，由于前额叶系统随年龄的变化，衰老大脑的补偿能力有限。
