Neuronal mechanisms of adult age aifferences in visual memory: EEG and fMRI investigations of network dynamics in "repetition priming"

支持学习和记忆的机制涉及包括前额叶、中颞叶和顶叶区域的分布式神经元网络中的同步相互作用。正常的衰老会影响大脑机制的组织和能力，这些机制在神经化学、神经解剖学和神经功能分析水平上支持学习和记忆。然而，这些变化对支持记忆的神经元网络及其与感知过程的相互作用的影响还没有得到很好的理解。我们建议调查的记忆衰退的神经元机制，在正常的认知老化管理的重复启动范例，其中重复介绍熟悉和不熟悉的项目，其次是一个惊喜的识别测试，年轻人和老年人的群体。在实验1中，我们研究了神经元的适应性效应所揭示的振荡伽马活动，使用脑电图记录。我们预测，老年人在感知和记忆网络中的持续神经元活动的同步性低于年轻人，导致重复暴露于熟悉和不熟悉的物品之间的差异不太明显。在实验2中，我们描绘了年轻人和老年人在大规模的神经网络支持视觉学习和记忆的高空间和时间分辨率相结合的EEG和功能磁共振成像评估的处理差异。具体来说，我们研究是否增加老年人的任务相关的前额叶激活减弱的不良后果，去分化的神经元处理在早期视觉处理领域的记忆性能（补偿招聘）。

Mechanisms supporting learning and memory involve synchronized interactions in distributed neuronal networks comprising prefrontal, medio-temporal, and parietal areas. Normal aging affects the organization and proficiency of brain mechanisms supporting learning and memory at neurochemical, neuroanatomical, and neurofunctional levels of analysis. However, the implications of these changes for neuronal networks supporting memory and its interactions with perceptual processes are not well understood. We propose to investigate neuronal mechanisms of memory decline in normal cognitive aging by administering a repetition-priming paradigm, in which repeated presentations of familiar and unfamiliar items are followed by a surprise recognition test, to groups of young and older adults. In Experiment 1, we investigate neuronal adaptation effects as revealed by oscillatory gamma activity using EEG recordings. We predict that older adults show less synchronization of ongoing neuronal activity in perceptual and mnemonic networks than young adults, resulting in less pronounced differences between repeated exposures to familiar and unfamiliar items. In Experiment 2, we delineate processing differences between young and older adults in large-scale neuronal networks supporting visual learning and memory with high spatial and temporal resolution by combining EEG and fMRI assessments. Specifically, we examine whether increased task-relevant prefrontal activation among older adults attenuates the adverse consequences of dedifferentiated neuronal processing in early visual processing areas on memory performance (compensatory recruitment).