The Role of the Posterior Medial Network in Language Comprehension: Dissociating Construction of Episodic versus Semantic Representations
The Role of the Posterior Medial Network in Language Comprehension: Dissociating Construction of Episodic versus Semantic Representations
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后内侧网络在语言理解中的作用：情景表征与语义表征的分离构建
DOI：
10.1101/2022.09.03.506471
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Branzi F
中科院分区：
文献类型：
--
作者：
Branzi F
语言理解涉及复杂心理表征的构建，即反映当前事件或情境模型的“事件表征”。这些表征的构建需要对语义和情景内容进行操作，并且与默认网络的一个子系统后内侧网络的功能广泛相关。然而，后内侧网络的活动在多大程度上反映了事件表征的可变情景和语义内容的构建，这一点尚不清楚。在这项fMRI研究中，我们建立了在叙事阅读任务中测量的(1)情景丰富性和(2)语义连贯性的独特神经关联。有趣的是，我们观察到脑后内侧网络的功能分化，其活动受到语义或情景内容的调节。具体来说，叙述中情节细节的数量调节了左角回和脾后皮层/腹侧后扣带皮层的活动。相反，语义连贯调节了右侧颞叶前部/颞中回的神经反应，但也调节了后内侧网络内的大脑区域，如后扣带皮层背侧。这些结果首次证明了后内侧网络在语言理解任务中参与语义和情景表征内容构建的大脑区域中存在功能性分离。“事件表征”的构建对于理解我们周围的世界、预测未来和制定计划至关重要，它需要对语义信息和情景信息进行操作。后内侧网络的功能与事件表征的形成密切相关。然而，尚不清楚该网络中的活动在多大程度上反映了事件表征的可变情景、语义内容的构建。本研究首次证明了后内侧网络在语言理解过程中涉及语义和情景表征内容构建的脑区中存在功能性分离。这些发现是理解情景和语义记忆系统在事件表征构建过程中如何运作的第一步。
Language comprehension involves the construction of complex mental representations, i.e., “event representations”, reflecting current events or situation models. The construction of these representations requires manipulation of both semantic and episodic content and has been widely associated with the functioning of the posterior medial network, a subsystem of the default network. However, it is still unknown the extent to which activity in posterior medial network reflects construction of the variable episodicversussemantic content of event representations. In this fMRI study, we establish the unique neural correlates of (1) episodic richness and (2) semantic coherence measured during a narrative reading task. Interestingly, we observed a functional fractionation within the posterior medial network in terms of brain regions whose activity was modulated by semantic or episodic content. Specifically, the number of episodic details in the narratives modulated the activity in the left angular gyrus and the retrosplenial cortex/ventral posterior cingulate cortex. Semantic coherence, in contrast, modulated neural responses in the right anterior temporal lobe/middle temporal gyrus, but also in brain regions within the posterior medial network, such as the dorsal posterior cingulate cortex. These results provide the first demonstration of functional dissociations within the posterior medial network in terms of brain regions involved in the construction of semanticversusepisodic representational content during a language comprehension task.Significance StatementThe construction of “event representations”, which is crucial to understand the world around us, predict the future and make plans, requires manipulation of both semantic and episodic information. The functioning of the posterior medial network has been tightly linked to formation of event representations. However, it is unclear the extent to which activity in this network reflects construction of the variable episodicversussemantic content of event representations. The present study provides the first demonstration of functional dissociations within posterior medial network in terms of brain regions involved in construction of semanticversusepisodic representational content during language comprehension. These findings represent a first step towards understanding how episodic and semantic memory systems operate during the construction of event representations.
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