Lee Yune Sang, Rogers Chad S, Grossman Murray, Wingfield Arthur, Peelle Jonathan E
Department of Speech, Language, and Hearing, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, TX, USA.
Department of Psychology, Union College, Schenectady, NY, USA.
Aging Brain. 2022 Aug 27;2:100051. doi: 10.1016/j.nbas.2022.100051. eCollection 2022.
We investigated how the aging brain copes with acoustic and syntactic challenges during spoken language comprehension. Thirty-eight healthy adults aged 54 - 80 years ( = 66 years) participated in an fMRI experiment wherein listeners indicated the gender of an agent in short spoken sentences that varied in syntactic complexity (object-relative vs subject-relative center-embedded clause structures) and acoustic richness (high vs low spectral detail, but all intelligible). We found widespread activity throughout a bilateral frontotemporal network during successful sentence comprehension. Consistent with prior reports, bilateral inferior frontal gyrus and left posterior superior temporal gyrus were more active in response to object-relative sentences than to subject-relative sentences. Moreover, several regions were significantly correlated with individual differences in task performance: Activity in right frontoparietal cortex and left cerebellum (Crus I & II) showed a negative correlation with overall comprehension. By contrast, left frontotemporal areas and right cerebellum (Lobule VII) showed a negative correlation with accuracy specifically for syntactically complex sentences. In addition, laterality analyses confirmed a lack of hemispheric lateralization in activity evoked by sentence stimuli in older adults. Importantly, we found different hemispheric roles, with a left-lateralized core language network supporting syntactic operations, and right-hemisphere regions coming into play to aid in general cognitive demands during spoken sentence processing. Together our findings support the view that high levels of language comprehension in older adults are maintained by a close interplay between a core left hemisphere language network and additional neural resources in the contralateral hemisphere.
我们研究了衰老的大脑在口语理解过程中如何应对听觉和句法挑战。38名年龄在54至80岁（平均年龄 = 66岁）的健康成年人参与了一项功能磁共振成像（fMRI）实验，在该实验中，听者要指出简短口语句子中施事者的性别，这些句子的句法复杂度不同（宾语关系从句与主语关系从句中心嵌入结构）且听觉丰富度不同（高光谱细节与低光谱细节，但均清晰可懂）。我们发现，在成功进行句子理解时，双侧额颞叶网络出现广泛活动。与先前的报告一致，双侧额下回和左侧颞上回后部对宾语关系从句的反应比对主语关系从句的反应更活跃。此外，几个区域与任务表现的个体差异显著相关：右侧额顶叶皮层和左侧小脑（蚓部I和II）的活动与整体理解呈负相关。相比之下，左侧额颞叶区域和右侧小脑（小叶VII）的活动与句法复杂句子的准确性呈负相关。此外，偏侧性分析证实，老年人句子刺激诱发的活动缺乏半球侧化。重要的是，我们发现了不同的半球作用，左侧半球为主的核心语言网络支持句法操作，而右侧半球区域在口语句子处理过程中发挥作用以帮助应对一般认知需求。我们的研究结果共同支持了这样一种观点，即老年人高水平的语言理解是由左侧半球核心语言网络与对侧半球的额外神经资源之间的紧密相互作用维持的。
