Imaging of Dementia and Aging (IDeA) Laboratory, Department of Neurology, University of California, Davis, Davis, CA 95618, USA.
Neurobiol Aging. 2012 Nov;33(11):2612-20. doi: 10.1016/j.neurobiolaging.2011.12.029. Epub 2012 Jan 27.
Age-related memory decline is the consequence of multiple biological factors that lead to brain structural and functional change, including gray matter atrophy, white matter injury, and loss of functional coordination between regions. However, the independent roles that each of these brain changes play in mediating memory decline is not clear. Therefore, we used magnetic resonance imaging (MRI) to measure gray matter (GM) volume, white matter hyperintensity (WMH) volumes, and blood oxygen level-dependent (BOLD) functional magnetic resonance imaging-based functional connectivity among default mode network nodes in 76 cognitive normal older adults. We found that GM, WMH, and connectivity between left inferior parietal and medial prefrontal cortex (MPF_LIP) were independently associated with episodic memory performance. Within the group with GM volumes below the median, greater MPF_LIP connectivity was associated with better memory performance, whereas this association was not present for individuals with GM volume above the median. These findings confirm the heterogeneous nature of brain-behavior relationships in cognitive aging. In addition, the relationship between resting state functional connectivity and memory performance, particularly amongst those individuals with more brain atrophy, strongly suggests compensation against the effects of neuronal injury.
年龄相关性记忆衰退是多种生物因素导致大脑结构和功能改变的结果，包括灰质萎缩、白质损伤以及区域间功能协调丧失。然而，这些大脑变化中的每一个在介导记忆衰退方面的独立作用尚不清楚。因此，我们使用磁共振成像（MRI）来测量 76 名认知正常的老年人的默认模式网络节点的灰质（GM）体积、白质高信号（WMH）体积和基于血氧水平依赖的（BOLD）功能磁共振成像的功能连接。我们发现 GM、WMH 和左侧顶下小叶和内侧前额叶皮质（MPF_LIP）之间的连接与情景记忆表现独立相关。在 GM 体积低于中位数的组中，MPF_LIP 之间的连接越强，记忆表现越好，而 GM 体积高于中位数的个体则没有这种关联。这些发现证实了认知老化中大脑-行为关系的异质性。此外，静息状态功能连接与记忆表现之间的关系，特别是在那些大脑萎缩程度更严重的个体中，强烈表明了对神经元损伤影响的补偿。
