Department of Linguistics, Hebrew University of Jerusalem, Mount Scopus, Jerusalem 9190501, Israel
Department of Psychology, Hebrew University of Jerusalem, Mount Scopus, Jerusalem 9190501, Israel.
J Neurosci. 2023 Nov 29;43(48):8189-8200. doi: 10.1523/JNEUROSCI.0235-23.2023.
Spontaneous speech is produced in chunks called intonation units (IUs). IUs are defined by a set of prosodic cues and presumably occur in all human languages. Recent work has shown that across different grammatical and sociocultural conditions IUs form rhythms of ∼1 unit per second. Linguistic theory suggests that IUs pace the flow of information in the discourse. As a result, IUs provide a promising and hitherto unexplored theoretical framework for studying the neural mechanisms of communication. In this article, we identify a neural response unique to the boundary defined by the IU. We measured the EEG of human participants (of either sex), who listened to different speakers recounting an emotional life event. We analyzed the speech stimuli linguistically and modeled the EEG response at word offset using a GLM approach. We find that the EEG response to IU-final words differs from the response to IU-nonfinal words even when equating acoustic boundary strength. Finally, we relate our findings to the body of research on rhythmic brain mechanisms in speech processing. We study the unique contribution of IUs and acoustic boundary strength in predicting delta-band EEG. This analysis suggests that IU-related neural activity, which is tightly linked to the classic Closure Positive Shift (CPS), could be a time-locked component that captures the previously characterized delta-band neural speech tracking. Linguistic communication is central to human experience, and its neural underpinnings are a topic of much research in recent years. Neuroscientific research has benefited from studying human behavior in naturalistic settings, an endeavor that requires explicit models of complex behavior. Usage-based linguistic theory suggests that spoken language is prosodically structured in intonation units. We reveal that the neural system is attuned to intonation units by explicitly modeling their impact on the EEG response beyond mere acoustics. To our understanding, this is the first time this is demonstrated in spontaneous speech under naturalistic conditions and under a theoretical framework that connects the prosodic chunking of speech, on the one hand, with the flow of information during communication, on the other.
自然语言以音节为单位进行表达，这些音节被称为音段单元（intonation units，IU）。IU 由一系列韵律线索定义，并且可能存在于所有人类语言中。最近的研究表明，在不同的语法和社会文化条件下，IU 形成约每秒 1 个单元的节奏。语言理论表明，IU 调节话语信息流的节奏。因此，IU 为研究交际的神经机制提供了一个有前途且尚未开发的理论框架。在本文中，我们确定了一个独特的神经反应，该反应与 IU 的边界有关。我们测量了人类参与者（无论性别）的脑电图，参与者听不同的说话者讲述一个情绪化的生活事件。我们对言语刺激进行了语言学分析，并使用 GLM 方法对单词结束时的 EEG 反应进行建模。我们发现，即使在均衡声学边界强度的情况下，IU 结尾词的 EEG 反应与 IU 非结尾词的反应也不同。最后，我们将我们的发现与言语处理中节奏脑机制的研究相结合。我们研究了 IU 和声学边界强度在预测 delta 波段 EEG 中的独特贡献。该分析表明，与 IU 相关的神经活动与经典的闭合正波（Closure Positive Shift，CPS）紧密相关，可能是一个时间锁定的成分，能够捕捉到以前描述的 delta 波段神经言语跟踪。语言交际是人类经验的核心，其神经基础是近年来研究的一个热点。神经科学研究受益于在自然环境中研究人类行为，这一努力需要对复杂行为进行明确的建模。基于使用的语言理论表明，口语是按照韵律单位（即音段单元）进行结构组织的。我们揭示了，通过明确建模 IU 对 EEG 反应的影响，超越了纯粹的声学影响，神经系统能够适应 IU。据我们所知，这是首次在自然条件下的口语中以及在一个将语音的韵律分段与交际过程中的信息流联系起来的理论框架下证明了这一点。
