Department of Advanced Medical and Surgical Sciences, School of Medicine and Surgery, University of Campania "Luigi Vanvitelli", Naples, Italy; Department of Medicine, Surgery and Dentistry, "Scuola Medica Salernitana", University of Salerno, Baronissi, Salerno, Italy.
Department of Political and Communication Sciences, University of Salerno, Fisciano, Salerno, Italy.
Cortex. 2022 Oct;155:132-149. doi: 10.1016/j.cortex.2022.07.005. Epub 2022 Aug 1.
Word-predictability measures, such as surprisal, have been used to show that linguistic prediction is an essential neural mechanism for successful comprehension. However, the neural dynamic of this mechanism may differ across individuals listening to the same narrative, revealing possible idiosyncrasies. Therefore, in this study, we investigated the ability of the surprisal measure to address the linguistic prediction in terms of the intersubject phase synchronization (ISPS) among healthy volunteers listening to a narrative during continuous functional Magnetic Resonance Imaging (fMRI) scanning. The data of twenty-seven participants, acquired in a previous study, were re-analyzed to estimate the ISPS associated with an audiobook listening, played forward and backward. Mean ISPS differences between playing conditions were first analyzed across the whole brain. ISPS time-series during the forward condition was explained with both a lexical-only and a semantics-weighted lexical surprisal model of the narrative word series to detect correlations between ISPS and word surprisal values. Compared to the backward condition, mean ISPS was significantly higher during forward condition in a broad network encompassing frontal, temporal, and parietal areas. The lexical-only model disclosed significant negative ISPS-surprisal correlations in the angular gyrus bilaterally, precuneus, left inferior parietal lobule, left middle frontal gyrus, left cerebellum, and left inferior frontal gyrus. The semantics-weighted surprisal model disclosed significant negative ISPS-surprisal correlations in the right angular gyrus, right precuneus, and left inferior frontal gyrus. Besides engaging language-related areas, narrative processing induces significant ISPS levels beyond the language network. The negative ISPS-surprisal correlations observed would signal divergent neural dynamics among individuals, leading to lower group synchronization, when the words to be integrated are characterized by higher surprisal levels. These results provide further support to the use of language models, such as the surprisal, to explain the neural processes of narrative comprehension and additional information into how the human brain exploits predictions during language comprehension.
词预测度测量，如惊讶度，已经被用于表明语言预测是成功理解的必要神经机制。然而，这种机制的神经动态可能因个体而异，即使他们在听相同的叙述。因此，在这项研究中，我们调查了惊讶度测量在健康志愿者连续功能磁共振成像 (fMRI) 扫描期间听叙述时的语言预测中的能力，研究了主体间相位同步 (ISPS)。我们重新分析了 27 名参与者在先前研究中获得的数据，以估计与有声读物播放相关的 ISPS，正向和反向播放。首先，在整个大脑范围内分析了两种播放条件之间的平均 ISPS 差异。使用叙事词系列的词汇唯一和语义加权词汇惊讶度模型来解释正向条件下的 ISPS 时间序列，以检测 ISPS 和词惊讶度值之间的相关性。与反向条件相比，正向条件下的平均 ISPS 在包括额、颞和顶叶区域在内的广泛网络中显著升高。词汇唯一模型在双侧角回、楔前叶、左顶下小叶、左额中回、左小脑和左额下回中发现显著的负 ISPS-惊讶度相关性。语义加权惊讶度模型在右角回、右楔前叶和左额下回中发现显著的负 ISPS-惊讶度相关性。除了参与语言相关区域外，叙述处理还会在语言网络之外诱导出显著的 ISPS 水平。当要整合的词具有较高的惊讶度水平时，观察到的负 ISPS-惊讶度相关性会发出个体之间不同的神经动力学信号，导致更低的组同步。这些结果进一步支持使用语言模型，如惊讶度，来解释叙述理解的神经过程，并提供更多信息说明人类大脑如何在语言理解过程中利用预测。
