Data_Sheet_1_Cortical Tracking of the Speech Envelope in Logopenic Variant Primary Progressive Aphasia.DOCX

Logopenic variant primary progressive aphasia (lvPPA) is a neurodegenerative language disorder primarily characterized by impaired phonological processing. Sentence repetition and comprehension deficits are observed in lvPPA and linked to impaired phonological working memory, but recent evidence also implicates impaired speech perception. Currently, neural encoding of the speech envelope, which forms the scaffolding for perception, is not clearly understood in lvPPA. We leveraged recent analytical advances in electrophysiology to examine speech envelope encoding in lvPPA. We assessed cortical tracking of the speech envelope and in-task comprehension of two spoken narratives in individuals with lvPPA (n = 10) and age-matched (n = 10) controls. Despite markedly reduced narrative comprehension relative to controls, individuals with lvPPA had increased cortical tracking of the speech envelope in theta oscillations, which track low-level features (e.g., syllables), but not delta oscillations, which track speech units that unfold across a longer time scale (e.g., words, phrases, prosody). This neural signature was highly correlated across narratives. Results indicate an increased reliance on acoustic cues during speech encoding. This may reflect inefficient encoding of bottom-up speech cues, likely as a consequence of dysfunctional temporoparietal cortex.

找词困难型变异型原发性进行性失语（Logopenic variant primary progressive aphasia，lvPPA）是一种以语音加工受损为核心特征的神经退行性语言障碍。该类患者可出现语句复述与理解障碍，此类缺陷既往被认为与语音工作记忆受损相关，但近年研究证据表明言语知觉损伤亦参与致病过程。目前，针对作为言语知觉核心框架的言语包络的神经编码机制，在lvPPA患者中仍未得到明确阐释。本研究借助电生理学领域近年的分析技术进展，对lvPPA患者的言语包络编码情况展开了考察。我们纳入10名lvPPA患者与10名年龄匹配的健康对照者，对两组受试者的言语包络皮层追踪能力，以及两项口头叙事任务的任务态理解能力进行了评估。尽管与健康对照组相比，lvPPA患者的叙事理解能力显著受损，但其在θ振荡频段的言语包络皮层追踪能力却有所增强；θ振荡可追踪音节等低水平言语特征，而δ振荡频段则未出现类似改变——δ振荡负责追踪更长时间尺度上展开的言语单元，如单词、短语与韵律。该神经特征在两项叙事任务中均呈现出高度相关性。研究结果提示，lvPPA患者在言语编码过程中对声学线索的依赖程度有所升高。这一现象可能反映了自下而上言语线索编码的低效性，其潜在机制大概率与颞顶叶皮层功能异常相关。