To understand language, we need to recognize words and combine them into phrases and sentences. During this process, responses to the words themselves are changed. In a step toward understanding how the brain builds sentence structure, the present study concerns the neural readout of this adaptation. We ask whether low-frequency neural readouts associated with words change as a function of being in a sentence. To this end, we analyzed an MEG dataset by Schoffelen et al. (2019) of 102 human participants (51 women) listening to sentences and word lists, the latter lacking any syntactic structure and combinatorial meaning. Using temporal response functions and a cumulative model-fitting approach, we disentangled delta- and theta-band responses to lexical information (word frequency), from responses to sensory and distributional variables. The results suggest that delta-band responses to words are affected by sentence context in time and space, over and above entropy and surprisal. In both conditions, the word frequency response spanned left temporal and posterior frontal areas; however, the response appeared later in word lists than in sentences. In addition, sentence context determined whether inferior frontal areas were responsive to lexical information. In the theta band, the amplitude was larger in the word list condition ~100 milliseconds in right frontal areas. We conclude that low-frequency responses to words are changed by sentential context. The results of this study show how the neural representation of words is affected by structural context and as such provide insight into how the brain instantiates compositionality in language.

SIGNIFICANCE STATEMENT Human language is unprecedented in its combinatorial capacity: we are capable of producing and understanding sentences we have never heard before. Although the mechanisms underlying this capacity have been described in formal linguistics and cognitive science, how they are implemented in the brain remains to a large extent unknown. A large body of earlier work from the cognitive neuroscientific literature implies a role for delta-band neural activity in the representation of linguistic structure and meaning. In this work, we combine these insights and techniques with findings from psycholinguistics to show that meaning is more than the sum of its parts; the delta-band MEG signal differentially reflects lexical information inside and outside sentence structures.

为了理解语言，我们需要识别单词并将它们组合成短语和句子。在此过程中，对词语本身的反应发生了变化。为了了解大脑如何构建句子结构，本研究关注这种适应的神经读出。我们询问与单词相关的低频神经读数是否会随着句子的变化而变化。为此，我们分析了 MEG 数据集舍弗伦等人。(2019)102 名人类参与者（51 名女性）聆听句子和单词列表，后者缺乏任何句法结构和组合意义。使用时间响应函数和累积模型拟合方法，我们将 delta 和 theta 频带对词汇信息（词频）的响应与对感觉和分布变量的响应分开。结果表明，对单词的 delta-band 响应受到时间和空间中句子上下文的影响，超出了熵和惊喜的影响。在这两种情况下，词频响应都跨越了左颞叶和后额叶区域；然而，答案在单词列表中出现的时间比在句子中出现的时间晚。此外，句子上下文还决定了额下区域是否对词汇信息有反应。在 θ 波段，在单词列表条件下，右额叶区域的振幅更大，约为 100 毫秒。我们得出的结论是，对单词的低频反应会因句子上下文而改变。这项研究的结果显示了单词的神经表征如何受到结构上下文的影响，因此提供了对大脑如何实例化语言中的组合性的见解。

意义陈述人类语言的组合能力是前所未有的：我们能够产生和理解以前从未听过的句子。尽管这种能力背后的机制已经在正式语言学和认知科学中得到描述，但它们在大脑中是如何实现的在很大程度上仍然未知。认知神经科学文献中的大量早期工作暗示了 δ 带神经活动在语言结构和意义表示中的作用。在这项工作中，我们将这些见解和技术与心理语言学的发现相结合，以表明意义不仅仅是其各部分的总和；delta-band MEG 信号差异化地反映了句子结构内部和外部的词汇信息。