老年人联结记忆一体化编码优势的认知神经机制

The associative deficits hypothesis suggests that normal aging is associated with a greater decline in associative memory relative to that of item memory. Aging-related decline in associative memory is attributed to their impaired recollection. Fortunately, familiarity is relatively preserved in older adults. Unitized encoding advantage means that unitization could effectively improve associative memory performance in older adults by enhancing the contribution of familiarity to associative retrieval. . The proposed project will investigate the neurocognitive mechanisms underlying the beneficial effects of unitization on associative memory in the older adults with behavioral and EEG/ERP techniques. Specifically speaking, we are interested in the differences between unitized representations and that of non-unitized representations during associative encoding, how study-test delay affects the retrieval of unitized representations, and whether the levels of unitization and amount of contextual information unitized during encoding modulate retrieval of unitized representations, and the underlying mechanisms. We predict that there are cognitive and neural dissociations between the unitized representations and non-unitized representations. We also expected that there are retention advantages for the unitized representations relative to the non-unitized representations. And the levels of unitization and amount of contextual information unitized will affect the associative memory performance and the neural activities during associative retrieval in older adults.. The proposed project has the potential to advance the understanding of cognitive aging, and provide support for the memory strategies training studies with neurocognitive evidence. The project will also have great implications for delaying cognitive aging and neurodegenerative diseases, and actively addressing the issue of the aging of the population.

老年人的情节记忆衰退主要表现为联结记忆成绩的下降。与传统的记忆策略相比，一体化编码策略能够增强熟悉性在联结记忆提取过程中的贡献，进而更有效地改善老年人的联结记忆成绩，此为老年人联结记忆的一体化编码优势。. 本研究结合行为学和EEG/ERP技术，拟从一体化加工的记忆编码过程，一体化加工的记忆保持效应，以及一体化加工的影响因素等角度出发，系统考察老年人一体化编码优势的认知神经机制。预期老年人一体化加工与非一体化加工在记忆编码阶段存在分离的认知神经机制；一体化的表征比非一体化表征具有更优的记忆保持效果；一体化编码程度高低和编码内容多少会影响老年人的联结记忆成绩以及联结记忆提取过程中的神经活动模式。. 本研究有助于深化对人类认知老化的认识，为老年人记忆策略训练研究提供科学依据，对预防和延缓神经退行性疾病，积极应对人口老龄化的挑战具有重要意义。

随着年龄的增长，老年人的认知功能会出现明显衰退，其中情节记忆是最突出的一个方面。本项目采用事件相关电位技术以及联结记忆范式，使用面孔材料操纵一体化水平，发现一体化编码能够增强熟悉感在联结记忆提取过程中的作用，为联结记忆的一体化假说提供了证据支持。在此基础上，使用词语配对材料，通过定义法和造句法两种编码策略来比较一体化编码vs.非一体化编码对老年人联结记忆成绩及其提取机制的影响。结果显示，老年人在定义一体化编码策略条件下的联结记忆成绩更好，且表现出显著的反映熟悉感的额区新旧效应，提示老年人的联结记忆存在一体化编码优势，为改善老年记忆功能的记忆策略训练研究提供了重要启示。. 此外，在项目的支持下，我们还考察了错误记忆的产生机制及其年龄差异。我们发现年轻人能够通过回想过程减少错误记忆的产生，而老年人则由于回想受损导致产生更多的错误再认。在此基础上，我们发现老年人主要通过后期的情节信息重构过程产生更多的高信心错误再认。另外，我们使用功能磁共振成像技术考察了老年人联结记忆衰退的脑机制，发现背外侧前额叶相关的脑网络能够预测主动使用记忆策略的老年人的联结记忆成绩，提示前额叶相关的脑网络可能通过调控记忆策略的使用来影响老年人的联结记忆成绩。最后，我们使用无创脑刺激技术对老年人的脑可塑性进行了探索。. 综上所述，本项目围绕老年人的一体化编码优势、回想过程受损、主观记忆衰退、记忆衰退的脑网络机制以及脑与认知可塑性等问题，对情节记忆年老化的认知神经机制及其可塑性开展了系统研究。上述成果对于积极应对人口老龄化具有重要意义。