CERVO Brain Research Center, Quebec City, Canada.
Département de Réadaptation, Faculté de Médecine, Université Laval, Quebec City, Canada.
Hum Brain Mapp. 2019 Jan;40(1):226-241. doi: 10.1002/hbm.24367. Epub 2018 Sep 12.
In this article, we used High Angular Resolution Diffusion Imaging (HARDI) with advanced anatomically constrained particle filtering tractography to investigate the role of the arcuate fasciculus (AF) and the middle longitudinal fasciculus (MdLF) in speech perception in noise in younger and older adults. Fourteen young and 15 elderly adults completed a syllable discrimination task in the presence of broadband masking noise. Mediation analyses revealed few effects of age on white matter (WM) in these fascicles but broad effects of WM on speech perception, independently of age, especially in terms of sensitivity and criterion (response bias), after controlling for individual differences in hearing sensitivity and head size. Indirect (mediated) effects of age on speech perception through WM microstructure were also found, after controlling for individual differences in hearing sensitivity and head size, with AF microstructure related to sensitivity, response bias and phonological priming, and MdLF microstructure more strongly related to response bias. These findings suggest that pathways of the perisylvian region contribute to speech processing abilities, with relatively distinct contributions for the AF (sensitivity) and MdLF (response bias), indicative of a complex contribution of both phonological and cognitive processes to age-related speech perception decline. These results provide new and important insights into the roles of these pathways as well as the factors that may contribute to elderly speech perception deficits. They also highlight the need for a greater focus to be placed on studying the role of WM microstructure to understand cognitive aging.
在本文中，我们使用高角度分辨率扩散成像（HARDI）和先进的解剖约束粒子滤波轨迹技术，研究了弓状束（AF）和中纵束（MdLF）在年轻和老年成年人噪声下言语感知中的作用。14 名年轻和 15 名老年成年人在宽带掩蔽噪声下完成了音节辨别任务。中介分析显示，年龄对这些束中的白质（WM）几乎没有影响，但 WM 对言语感知有广泛的影响，独立于年龄，特别是在敏感性和标准（反应偏差）方面，在控制了听力敏感性和头部大小的个体差异后。在控制了听力敏感性和头部大小的个体差异后，也发现了 WM 微观结构对言语感知的间接（中介）影响，AF 微观结构与敏感性、反应偏差和语音启动有关，而 MdLF 微观结构与反应偏差的关系更密切。这些发现表明，周围区域的通路有助于言语处理能力，AF（敏感性）和 MdLF（反应偏差）的贡献相对独特，表明语音和认知过程对年龄相关的言语感知下降有复杂的贡献。这些结果为这些通路的作用以及可能导致老年人言语感知缺陷的因素提供了新的重要见解。它们还强调了需要更加关注研究 WM 微观结构的作用，以了解认知衰老。
