Department of Psychology, Boston College Chestnut Hill, MA, USA.
Front Hum Neurosci. 2014 May 16;8:307. doi: 10.3389/fnhum.2014.00307. eCollection 2014.
The last decade has seen an increase in neuroimaging studies examining structural (i.e., structural integrity of white matter tracts) and functional connectivity (e.g., correlations in neural activity throughout the brain). Although structural and functional connectivity changes have often been measured independently, examining the relation between these two measures is critical to understanding the specific function of neural networks and the ways they may differ across tasks and individuals. The current study addressed this question by examining the effect of age (treated as a continuous variable) and emotional valence on the relation between functional and structural connectivity. As prior studies have suggested that prefrontal regions may guide and regulate emotional memory search via functional connections with the amygdala, the current analysis focused on functional connectivity between the left amygdala and the left prefrontal cortex, and structural integrity of the uncinate fasciculus, a white matter tract connecting prefrontal and temporal regions. Participants took part in a scanned retrieval task in which they recalled positive, negative, and neutral images associated with neutral titles. Aging was associated with a significant increase in the relation between measures of structural integrity (specifically, fractional anisotropy, or FA) along the uncinate fasciculus and functional connectivity between the left ventral prefrontal cortex and amygdala during positive event retrieval, but not negative or neutral retrieval. Notably, during negative event retrieval, age was linked to stronger structure-function relations between the amygdala and the dorsal anterior cingulate cortex, such that increased structural integrity predicted stronger negative functional connectivity in older adults only. These findings suggest that young and older adults may utilize a structural pathway to engage different retrieval and regulatory strategies, even when structural integrity along that pathway does not differ.
过去十年中，越来越多的神经影像学研究关注结构连接（即白质束的结构完整性）和功能连接（例如大脑中神经活动的相关性）。尽管结构和功能连接的变化经常是独立测量的，但检查这两种测量之间的关系对于理解神经网络的特定功能以及它们在不同任务和个体中可能存在的差异方式至关重要。本研究通过检查年龄（视为连续变量）和情绪效价对功能和结构连接之间关系的影响来解决这个问题。由于先前的研究表明，前额叶区域可能通过与杏仁核的功能连接来指导和调节情绪记忆搜索，因此当前的分析集中在左杏仁核和左前额叶皮层之间的功能连接，以及连接前额叶和颞叶区域的白质束钩束的结构完整性上。参与者参与了一项扫描检索任务，在该任务中，他们回忆与中性标题相关的积极、消极和中性图像。随着年龄的增长，在与钩束结构完整性（特别是各向异性分数，或 FA）相关的测量值与左腹侧前额叶皮层和杏仁核之间功能连接之间的关系中，年龄与正性事件检索时的关系显著增加，但在负性或中性检索时则没有。值得注意的是，在负性事件检索时，年龄与杏仁核和背侧前扣带皮层之间的结构-功能关系更强相关，因此只有在老年人中，结构完整性的增加预测了更强的负性功能连接。这些发现表明，年轻和老年成年人可能会利用结构途径来采用不同的检索和调节策略，即使该途径的结构完整性没有差异。
