School of Communication Sciences & Disorders, University of Memphis, Memphis, TN, USA; Institute for Intelligent Systems, University of Memphis, Memphis, TN, USA.
Department of Speech, Language and Hearing Sciences, Indiana University, Bloomington, IN, USA; Program in Neuroscience, Indiana University, Bloomington, IN, USA; Cognitive Science Program, Indiana University, Bloomington, IN, USA.
Brain Lang. 2024 Sep;256:105463. doi: 10.1016/j.bandl.2024.105463. Epub 2024 Sep 7.
We investigated how neural oscillations code the hierarchical nature of stress rhythms in speech and how stress processing varies with language experience. By measuring phase synchrony of multilevel EEG-acoustic tracking and intra-brain cross-frequency coupling, we show the encoding of stress involves different neural signatures (delta rhythms = stress foot rate; theta rhythms = syllable rate), is stronger for amplitude vs. duration stress cues, and induces nested delta-theta coherence mirroring the stress-syllable hierarchy in speech. Only native English, but not Mandarin, speakers exhibited enhanced neural entrainment at central stress (2 Hz) and syllable (4 Hz) rates intrinsic to natural English. English individuals with superior cortical-stress tracking capabilities also displayed stronger neural hierarchical coherence, highlighting a nuanced interplay between internal nesting of brain rhythms and external entrainment rooted in language-specific speech rhythms. Our cross-language findings reveal brain-speech synchronization is not purely a "bottom-up" but benefits from "top-down" processing from listeners' language-specific experience.
我们研究了神经振荡如何对言语中应激节律的层次结构进行编码，以及应激处理如何随语言经验而变化。通过测量多层次 EEG-声学跟踪和大脑内跨频耦合的相位同步，我们表明应激的编码涉及不同的神经特征（δ节律=应激步速；θ节律=音节率），对于幅度与持续时间的应激线索更强，并且诱导嵌套的δ-θ相干性，反映言语中的应激-音节层次结构。只有英语母语者而不是汉语母语者表现出对中央应激（2 Hz）和音节（4 Hz）固有自然英语率的增强神经同步。具有优越皮质应激跟踪能力的英语个体也表现出更强的神经层次相干性，突出了大脑节律的内部嵌套与源于特定语言的言语节律的外部同步之间的细微相互作用。我们的跨语言发现揭示了脑-言语同步不仅仅是纯粹的“自下而上”的，而是受益于听众特定语言经验的“自上而下”处理。
