Department of Psychology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.
Department of Psychology, Maynooth University, Maynooth, Ireland.
Eur J Neurosci. 2019 Dec;50(11):3855-3872. doi: 10.1111/ejn.14530. Epub 2019 Aug 16.
Older adults display difficulties in encoding and retrieval of information, resulting in poorer memory. This may be due to an inability of older adults to engage elaborative encoding strategies during learning. This study examined behavioural and electrophysiological effects of explicit cues to self-initiate learning during encoding and subsequent recognition of words in younger adults (YA), older control adults (OA) and older adults with relative memory impairment (OD). The task was a variation of the old/new paradigm, some study items were preceded by a cue to learn the word (L) while others by a do not learn cue (X). Behaviourally, YA outperformed OA and OD on the recognition task, with no significant difference between OA and OD. Event-related potentials at encoding revealed enhanced early visual processing (70-140 ms) for L- versus X-words in young and old. Only YA exhibited a greater late posterior positivity (LPP; 200-500 ms) for all words during encoding perhaps reflecting superior encoding strategy. During recognition, only YA differentiated L- versus X-words with enhanced frontal P200 (150-250 ms) suggesting impaired early word selection for retrieval in older groups; however, OD had enhanced P200 activity compared to OA during L-word retrieval. The LPP (250-500 ms) was reduced in amplitude for L-words compared to both X- and new words. However, YA showed greater LPP amplitude for all words compared to OA. For older groups, we observed reduced left parietal hemispheric asymmetry apparent in YA during encoding and recognition, especially for OD. Findings are interpreted in the light of models of compensation and dedifferentiation associated with age-related changes in memory function.
老年人在信息编码和提取方面存在困难，导致记忆力下降。这可能是由于老年人在学习过程中无法采用详细的编码策略。本研究考察了在编码过程中使用明确的自我启动学习线索以及随后识别年轻人（YA）、老年对照组（OA）和有相对记忆障碍的老年人（OD）的单词时的行为和电生理效应。任务是新旧范式的一种变体，一些学习项目前面有一个学习单词的线索（L），而另一些则有一个不学习的线索（X）。行为上，YA 在识别任务中的表现优于 OA 和 OD，而 OA 和 OD 之间没有显著差异。编码时的事件相关电位显示，与 X-单词相比，L-单词的早期视觉处理（70-140ms）增强，年轻人和老年人都有这种情况。只有 YA 在编码过程中对所有单词表现出更大的后顶叶正波（LPP；200-500ms），这可能反映了更好的编码策略。在识别过程中，只有 YA 区分了 L-和 X-单词，并且在 L-单词的额前 P200（150-250ms）增强，这表明在老年人组中检索时早期单词选择受损；然而，OD 在 L-单词检索期间的 P200 活动比 OA 增强。与 X-和新单词相比，L-单词的 LPP（250-500ms）的幅度减小。然而，与 OA 相比，YA 显示出所有单词的 LPP 幅度都更大。对于老年人组，我们观察到在编码和识别过程中，尤其是对于 OD，左顶叶半球的不对称性明显减小，这与与年龄相关的记忆功能变化相关的补偿和去分化模型相一致。研究结果在解释时考虑到了与年龄相关的记忆功能变化相关的补偿和去分化模型。
