Xu Na, Qin Xiaoxiao, Zhou Ziqi, Shan Wei, Ren Jiechuan, Yang Chunqing, Lu Lingxi, Wang Qun
Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China.
National Clinical Research Center for Neurological Diseases, Beijing 100070, China.
Cereb Cortex. 2023 Sep 26;33(19):10463-10474. doi: 10.1093/cercor/bhad296.
Speech comprehension requires listeners to rapidly parse continuous speech into hierarchically-organized linguistic structures (i.e. syllable, word, phrase, and sentence) and entrain the neural activities to the rhythm of different linguistic levels. Aging is accompanied by changes in speech processing, but it remains unclear how aging affects different levels of linguistic representation. Here, we recorded magnetoencephalography signals in older and younger groups when subjects actively and passively listened to the continuous speech in which hierarchical linguistic structures of word, phrase, and sentence were tagged at 4, 2, and 1 Hz, respectively. A newly-developed parameterization algorithm was applied to separate the periodically linguistic tracking from the aperiodic component. We found enhanced lower-level (word-level) tracking, reduced higher-level (phrasal- and sentential-level) tracking, and reduced aperiodic offset in older compared with younger adults. Furthermore, we observed the attentional modulation on the sentential-level tracking being larger for younger than for older ones. Notably, the neuro-behavior analyses showed that subjects' behavioral accuracy was positively correlated with the higher-level linguistic tracking, reversely correlated with the lower-level linguistic tracking. Overall, these results suggest that the enhanced lower-level linguistic tracking, reduced higher-level linguistic tracking and less flexibility of attentional modulation may underpin aging-related decline in speech comprehension.
言语理解要求听众迅速将连续的言语解析为层次组织的语言结构（即音节、单词、短语和句子），并使神经活动与不同语言层次的节奏同步。衰老伴随着言语处理的变化，但衰老如何影响不同层次的语言表征仍不清楚。在此，我们记录了老年组和青年组在主动和被动聆听连续言语时的脑磁图信号，其中单词、短语和句子的层次语言结构分别以4、2和1赫兹进行标记。应用一种新开发的参数化算法将周期性语言追踪与非周期性成分分离。我们发现，与年轻人相比，老年人的低层次（单词层次）追踪增强，高层次（短语和句子层次）追踪减少，非周期性偏移减少。此外，我们观察到，年轻人在句子层次追踪上的注意力调制比老年人更大。值得注意的是，神经行为分析表明，受试者的行为准确性与高层次语言追踪呈正相关，与低层次语言追踪呈负相关。总体而言，这些结果表明，低层次语言追踪增强、高层次语言追踪减少以及注意力调制灵活性降低可能是衰老相关言语理解能力下降的基础。
