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Poster B36, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall

Semantic Integration During Language Comprehension in Natural Contexts

Mengxing Liu1,2, Xiaojuan Wang1, Xiangyang Zhang1, Rui Zhang1, Pedro M. Paz-Alonso2, Jianfeng Yang1;1Shaanxi Normal University, 2Basque Center on Cognition, Brain and Language

Successful comprehension of language relies on effectively integrating information online with our semantic knowledge. Cognitive neuroscience has recently investigated the neural mechanisms underlining semantic integration highlighting the role of left-lateralized regions along the language network, including the inferior frontal gyrus (IFG), the posterior superior and middle temporal gyrus (STG/MTG), the angular gyrus (AG) and the anterior temporal lobe (ATL). Most of the previous neuroimaging evidence examining the role of these regions comes from studies contrasting congruent versus incongruent sentences, or ambiguous versus unambiguous sentences. In the present fMRI study, we sought to better understand the mechanisms supporting semantic integration using naturalistic materials and a inter-subject correlation analytical approach without explicitly modeling the integration process. To this end, a total of 30 right-handed adult participants were asked to read or to listen natural stories silently while undergoing MRI scanning. More specifically, participants performed a comprehension task involving reading or listening five stories (i.e. fairy tales) in Chinese, with one full story presented in each run. The main experimental conditions were sentences that, belonging to a different unrelated story, were inserted at six different points of the ongoing main story, and included: coherent sentences (CS), or sentences from another story presented in their natural order; unconnected sentences (US) or sentences from another story presented in an altered order in relation to their natural order; and, scrambled word lists (SW) or sentences from another story in which the word ordering was scrambled within each sentence. Thus, we manipulated the units at which semantic integration was possible within these conditions: at the paragraph level for CS; at the sentence level for US; and, at the single-word level for SW. To identify the involvement of brain regions without modeling the specific stimuli time course, we measured across individuals the correlation of the BOLD signal evoked by the same stimuli in each condition within and between reading and listening tasks. First, we mapped the inter-subject correlation for each condition CS/US/SW within both reading and listening tasks, by correlating the fMRI time courses across subjects. The results indicated that the BOLD-response reliability (i.e. observed correlations) varied across associative regions as a function of semantic integration level. Second, to further identify areas that reliably respond to integrating the same semantic content, we mapped the areas that shared the similar response between listening and reading tasks. A clear gradient along the temporal lobe was observed upon varying the semantic integration level, with more extensive and stronger correlations observed from anterior to posterior MTG/STG and AG as a function of the units that can be semantically integrated. Moreover, the posterior IFG only showed BOLD-response reliability between modalities for the CS condition. In sum, using naturalistic materials and an inter-subject correlation analytical approach, the results from the present study highlight the stronger involvement of perisylvian areas as a function of the units that can be semantically integrated across language comprehension modalities.

Themes: Meaning: Combinatorial Semantics, Meaning: Lexical Semantics
Method: Functional Imaging

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