Poster E27, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall
The dynamic cognitive process and brain networks by which predictive processing facilitates language comprehension
Xiaoqing Li1, Ximing Shao1, Zaizhu Han2;1CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, 2State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University
Both language processing theories and experimental studies suggest that, during language comprehension, the human brain can use prior knowledge and contextual information to predict upcoming content, and these internally generated predictions are potentially able to provide constraints to the representation of new bottom-up input, thereby facilitating language comprehension. The present fMRI (functional magnetic resonance imaging) study examined the dynamic cognitive process and brain networks by which predictive processing is conducted to facilitate language comprehension. Participants read Mandarin Chinese sentences for comprehension during fMRI data acquisition. Three versions of sentences were constructed (StrongTool, StrongBuilding, vs. Weak): the sentences had an either strong- or weak-constraint semantic context, and meanwhile the strong-constraint context set a high expectation for either a building- or tool-noun. The critical nouns (at the sentence-final position) were all the best completion of their context, and the critical verbs (immediately preceding these nouns) were exactly the same in the three versions. The effects of semantic prediction were examined by measuring both the anticipatory processing of the critical nouns prior to their onset and the integration processing of these nouns after their appearance. The results showed that, firstly, at both the anticipatory and integration stages of semantic prediction, left parahippocampal gyrus, which is considered to be correlated with the representations of buildings, displayed increased activations in the StrongBuilding condition (for both StrongBuilding-versus-StrongTool and StrongBuilding-versus-Weak contrasts); left pMTG (posterior middle temporal gyrus) and left ITG (inferior temporal gyrus), which have been considered to be associated with tool-related representations, showed increased activities in the StrongTool condition (for both StrongTool-versus-StrongBuilding and StrongTool-versus-Weak contrasts). These results indicated that, during the processing of strongly constraining sentences, brain areas associated with specific semantic representations displayed not only increased activities but pre-activations as well. Secondly, left MTG (middle temporal gyrus), which is considered to be correlated with lexical/semantic retrieval process, displayed decreased activations in the strong-constraint conditions (StrongTool+StrongBuilding versus WEAK) at both the anticipatory and integration stages of processing, suggesting facilitated lexical-semantic retrieval in a strongly constraining context. Thirdly, left IFG (inferior frontal gyrus), which has been considered to related to semantic unification/binding process, demonstrated increased activation in the strong-constraint conditions (StrongTool+StrongBuilding versus WEAK) at the anticipatory stage of processing, but decreased activations at the integration stage of processing. These two stages of left IFG activities indicated that, while reading the strong-constraint sentence for comprehension, the human brain consumed more neural/cognitive resources to bind the currently available information to generate hypothesized representations of incoming words, and these neural/cognitive cost got a beneficial effect at a later stage, as indicated by facilitated integration of the actually presented new language input. In addition, bilateral middle frontal gyrus, thalamus, and supplementary motor areas also showed decreased activations in the strong-constraint conditions at the integration stage. Finally, we discussed how the different brain areas (e.g., areas associated with semantic representations, semantic retrieval/unification, and general predictive coding processing) worked cooperately and dynamically to help us to perform predictive processing to facilitate language comprehension.
Themes: Meaning: Combinatorial Semantics, Meaning: Lexical Semantics
Method: Functional Imaging