White matter microstructure contributes to age-related declines in task-induced deactivation of the default mode network.
White matter microstructure contributes to age-related declines in task-induced deactivation of the default mode network.
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DOI：
10.3389/fnagi.2015.00194
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发表时间：
2015
影响因子：
4.8
通讯作者：
Gold BT
中科院分区：
文献类型：
--
作者：
Brown CA;Hakun JG;Zhu Z;Johnson NF;Gold BT
大脑默认模式网络（DMN）内的任务诱导的去激活被认为反映了对内源性思维过程的抑制，以支持外源性目标导向的任务过程。已知老年人与年轻人相比表现出DMN失活的减少。然而，很少有人了解的机制，有助于功能失调的DMN在老化。本研究旨在探讨DMN的功能调节与年龄、任务绩效和白色物质（WM）微结构之间的关系。参与者是117名年龄从25岁到83岁的成年人，他们完成了fMRI任务切换范式，包括简单（单一）和困难（混合）条件，并进行了扩散张量成像（DTI）。功能磁共振成像结果显示年龄与条件的相互作用（β =-0.13，t =-3.16，p = 0.002），在混合条件下（β =-0.29，t =-3.24，p = 0.002），年龄的增加会影响失活幅度，但在单一条件下（p = 0.58）则不会。此外，存在WM与条件的相互作用（β = 0.10，t = 2.33，p = 0.02），使得减小WM微观结构影响混合条件期间的失活程度（β = 0.30，t = 3.42 p = 0.001），但不影响单一条件（p = 0.17）。重要的是，调解分析表明，年龄相关的减少WM微观结构占年龄和DMN失活之间的关系，在更困难的混合条件。这些发现表明，年龄相关的DMN区域之间的解剖连接性下降有助于老年人DMN内的功能失调。
Task-induced deactivations within the brain’s default mode network (DMN) are thought to reflect suppression of endogenous thought processes to support exogenous goal-directed task processes. Older adults are known to show reductions in deactivation of the DMN compared to younger adults. However, little is understood about the mechanisms contributing to functional dysregulation of the DMN in aging. Here, we explored the relationships between functional modulation of the DMN and age, task performance and white matter (WM) microstructure. Participants were 117 adults ranging from 25 to 83 years old who completed an fMRI task switching paradigm, including easy (single) and difficult (mixed) conditions, and underwent diffusion tensor imaging (DTI). The fMRI results revealed an age by condition interaction (β = −0.13, t = −3.16, p = 0.002) such that increasing age affected deactivation magnitude during the mixed condition (β = −0.29, t = −3.24 p = 0.002) but not the single condition (p = 0.58). Additionally, there was a WM by condition interaction (β = 0.10, t = 2.33, p = 0.02) such that decreasing WM microstructure affected deactivation magnitude during the mixed condition (β = 0.30, t = 3.42 p = 0.001) but not the single condition (p = 0.17). Critically, mediation analyses indicated that age-related reductions in WM microstructure accounted for the relationship between age and DMN deactivation in the more difficult mixed condition. These findings suggest that age-related declines in anatomical connectivity between DMN regions contribute to functional dysregulation within the DMN in older adults.