Baran Bengi, Mantua Janna, Spencer Rebecca M C
University of Massachusetts.
J Cogn Neurosci. 2016 Jun;28(6):792-802. doi: 10.1162/jocn_a_00938. Epub 2016 Feb 26.
Consolidation of declarative memories has been associated with slow wave sleep in young adults. Previous work suggests that, in spite of changes in sleep, sleep-dependent consolidation of declarative memories may be preserved with aging, although reduced relative to young adults. Previous work on young adults shows that, with consolidation, retrieval of declarative memories gradually becomes independent of the hippocampus. To investigate whether memories are similarly reorganized over sleep at the neural level, we compared functional brain activation associated with word pair recall following a nap and equivalent wake in young and older adults. SWS during the nap predicted better subsequent memory recall and was negatively associated with retrieval-related hippocampal activation in young adults. In contrast, in older adults there was no relationship between sleep and memory performance or with retrieval-related hippocampal activation. Furthermore, compared with young adults, postnap memory retrieval in older adults required strong functional connectivity of the hippocampus with the PFC, whereas there were no differences between young and older adults in the functional connectivity of the hippocampus following wakefulness. These results suggest that, although neural reorganization takes place over sleep in older adults, the shift is unique from that seen in young adults, perhaps reflecting memories at an earlier stage of stabilization.
陈述性记忆的巩固与年轻人的慢波睡眠有关。先前的研究表明，尽管睡眠发生了变化，但陈述性记忆的睡眠依赖性巩固可能会随着年龄增长而保留下来，尽管相对于年轻人来说有所减少。先前对年轻人的研究表明，随着记忆的巩固，陈述性记忆的提取逐渐变得独立于海马体。为了研究在神经层面上记忆在睡眠期间是否也会以类似的方式重新组织，我们比较了年轻人和老年人在午睡和同等时长清醒状态后与单词对回忆相关的大脑功能激活情况。午睡期间的慢波睡眠预示着随后更好的记忆回忆，并且与年轻人中与提取相关的海马体激活呈负相关。相比之下，在老年人中，睡眠与记忆表现之间以及与提取相关的海马体激活之间没有关系。此外，与年轻人相比，老年人午睡后的记忆提取需要海马体与前额叶皮质之间有很强的功能连接，而清醒后年轻人和老年人在海马体的功能连接方面没有差异。这些结果表明，尽管老年人在睡眠期间会发生神经重组，但这种转变与年轻人的情况不同，这可能反映了记忆处于更早的稳定阶段。
