Bauer Eva, Sammer Gebhard, Toepper Max
Cognitive Neuroscience at the Centre for Psychiatry, University of Giessen, Giessen, Germany.
Department of Psychology, University of Giessen, Giessen, Germany.
Front Aging Neurosci. 2018 Sep 11;10:265. doi: 10.3389/fnagi.2018.00265. eCollection 2018.
There is evidence that the neural response to increasing working memory (WM) load is modulated by age and performance level. For a valid interpretation of these effects, however, it is important to understand, whether and how they are related to gray matter atrophy. In the current work, we therefore used functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM) to examine the association between age, performance level, spatial WM load-related brain activation and gray matter volume in 18 younger high-performers (YHP), 17 younger low-performers (YLP), 17 older high-performers (OHP), and 18 older low-performers (OLP). In multiple sub regions of the prefrontal cortex (PFC), load-related activation followed a linear trend with increasing activation at increasing load in all experimental groups. Results did not reveal differences between the sub groups. Older adults additionally showed a pattern of increasing activation from low to medium load but stable or even decreasing activation from medium to high load in other sub regions of the PFC (quadratic trend). Quadratic trend related brain activation was higher in older than in younger adults and in OLP compared to OHP. In OLP, quadratic trend related brain activation was negatively correlated with both performance accuracy and prefrontal gray matter volume. The results suggest an efficient upregulation of multiple PFC areas as response to increasing WM load in younger and older adults. Older adults and particularly OLP additionally show dysfunctional response patterns (i.e., enhanced quadratic trend related brain activation compared to younger adults and OHP, respectively) in other PFC clusters being associated with gray matter atrophy.
有证据表明，对工作记忆（WM）负荷增加的神经反应会受到年龄和表现水平的调节。然而，为了对这些效应做出有效的解释，了解它们是否以及如何与灰质萎缩相关是很重要的。因此，在当前的研究中，我们使用功能磁共振成像（fMRI）和基于体素的形态学测量（VBM）来检查18名年轻高表现者（YHP）、17名年轻低表现者（YLP）、17名年长高表现者（OHP）和18名年长低表现者（OLP）的年龄、表现水平、空间WM负荷相关的大脑激活与灰质体积之间的关联。在额叶前皮质（PFC）的多个子区域中，负荷相关的激活呈现线性趋势，所有实验组中随着负荷增加激活也增加。结果未显示亚组之间存在差异。年长成年人在PFC的其他子区域还表现出从低负荷到中等负荷激活增加，但从中等负荷到高负荷激活稳定甚至下降的模式（二次趋势）。与年轻人相比，年长成年人以及与OHP相比，OLP中二次趋势相关的大脑激活更高。在OLP中，二次趋势相关的大脑激活与表现准确性和额叶前皮质灰质体积均呈负相关。结果表明，在年轻人和年长成年人中，多个PFC区域对增加的WM负荷做出了有效的上调反应。年长成年人，尤其是OLP，在其他与灰质萎缩相关的PFC簇中还表现出功能失调的反应模式（即分别比年轻人和OHP增强了二次趋势相关的大脑激活）。
