Center for Lifespan Psychology, Max Planck Institute for Human Development, 14195 Berlin, Germany, and
Center for Lifespan Psychology, Max Planck Institute for Human Development, 14195 Berlin, Germany, and.
J Neurosci. 2019 Oct 9;39(41):8089-8099. doi: 10.1523/JNEUROSCI.0197-19.2019. Epub 2019 Aug 9.
Age-related memory decline is associated with changes in neural functioning, but little is known about how aging affects the quality of information representation in the brain. Whereas a long-standing hypothesis of the aging literature links cognitive impairments to less distinct neural representations in old age ("neural dedifferentiation"), memory studies have shown that overlapping neural representations of different studied items are beneficial for memory performance. In an electroencephalography (EEG) study, we addressed the question whether distinctiveness or similarity between patterns of neural activity supports memory differentially in younger and older adults. We analyzed between-item neural pattern similarity in 50 younger (19-27 years old) and 63 older (63-75 years old) male and female human adults who repeatedly studied and recalled scene-word associations using a mnemonic imagery strategy. We compared the similarity of spatiotemporal EEG frequency patterns during initial encoding in relation to subsequent recall performance. The within-person association between memory success and pattern similarity differed between age groups: For older adults, better memory performance was linked to higher similarity early in the encoding trials, whereas young adults benefited from lower similarity between earlier and later periods during encoding, which might reflect their better success in forming unique memorable mental images of the joint picture-word pairs. Our results advance the understanding of the representational properties that give rise to subsequent memory, as well as how these properties may change in the course of aging. Declining memory abilities are one of the most evident limitations for humans when growing older. Despite recent advances of our understanding of how the brain represents and stores information in distributed activation patterns, little is known about how the quality of information representation changes during aging and thus affects memory performance. We investigated how the similarity between neural representations relates to subsequent memory in younger and older adults. We present novel evidence that the interaction of pattern similarity and memory performance differs between age groups: Older adults benefited from higher similarity during early encoding, whereas young adults benefited from lower similarity between early and later encoding. These results provide insights into the nature of memory and age-related memory deficits.
与神经功能变化相关的与年龄相关的记忆衰退，但人们对衰老如何影响大脑中信息表示的质量知之甚少。虽然衰老文献中的一个长期假设将认知障碍与老年时期不太明显的神经表示联系起来（“神经去分化”），但记忆研究表明，不同研究项目的重叠神经表示对记忆表现有益。在脑电图（EEG）研究中，我们研究了在年轻和老年成年人中，模式之间的独特性或相似性是否不同程度地支持记忆的问题。我们分析了 50 名年轻成年人（19-27 岁）和 63 名老年成年人（63-75 岁）的男女中项目间神经模式相似性，他们使用记忆意象策略反复学习和回忆场景-词联想。我们比较了初始编码期间的时空 EEG 频率模式的相似性与随后的回忆表现。记忆成功与模式相似性之间的个体内关联在年龄组之间有所不同：对于老年成年人，更好的记忆表现与编码试验早期的更高相似性相关，而年轻成年人则受益于编码期间早期和晚期之间的较低相似性，这可能反映了他们成功地形成了联合图片-单词对的独特可记忆的心理图像。我们的结果提高了对产生后续记忆的表示属性的理解，以及这些属性如何随着年龄的增长而变化。随着年龄的增长，记忆能力下降是人类最明显的限制之一。尽管我们对大脑如何以分布式激活模式表示和存储信息的理解最近有所提高，但对于信息表示的质量如何在衰老过程中发生变化从而影响记忆表现知之甚少。我们研究了神经表示之间的相似性与年轻和老年成年人的后续记忆之间的关系。我们提供了新的证据，表明模式相似性和记忆表现之间的相互作用在年龄组之间有所不同：老年成年人在早期编码期间受益于更高的相似性，而年轻成年人在早期和后期编码之间受益于较低的相似性。这些结果为记忆和与年龄相关的记忆缺陷的本质提供了见解。
