认知与发展心理学研究室知识库

在语言理解中，自上而下的预期加工起到非常重要的作用。己有研究主要通过高预期条件下关键词出现后其加工的促进效应来间接证明预期的存在，但是对于真正产生预期的过程及其神经基础目前直接的研究证据还比较少。

本研究通过隔开“关键名词”及其前面的“关键动词”从而分开考察预期的“形成阶段”和“整合阶段”，同时操纵句子的语义限制性高低和关键名词的语义类别。实验1自定步速阅读的行为实验结果表明，两种高预期条件下，预期阶段的反应时高于低预期条件，说明高预期条件下预期阶段需要花费更长时间进行预期加分析结果表明，在预期阶段，高预期条件与低预期条件相比，在左侧额下回激活增强，在左侧颗中回激活降低。在整合阶段，高预期条件相比低预期条件在左侧额上/中/下回，左侧颗中/上回、双侧丘脑、双侧尾状核、双侧枕叶等区域激活降低。而无论是预期阶段还是整合阶段，“高预期一建筑”条件在负责建筑词语义表征的左侧海马旁回相比“高预期一工具”条件和低预期条件有更高激活，“高预期-工具词”条件在负责工具词语义表征的左侧颗下回相比于“高预期一建筑”条件和低预期条件有更高激活。研究结果表明早在预期阶段高预期条件下己经可以预先激活所预期词语的语义表征，同时左侧额下回的活动增强参与预期的过程。而在整合阶段，高预期条件下整合加工得到易化，左侧额叶、颗叶，双侧枕叶以及皮下核团等区域的激活降低说明这些区域参与整合加工。

Top-down anticipatory processing plays an important role during language comprehension. Existing studies mainly provided indirect evidence for the existence of predictions by showing the facilitation effect of highly-predicted information. But the mechanism and neural basis of the predictive process still remain unknown.

In this study, we investigated the effect at the "anticipatory stage" and the "integration stage" respectively by separating the "critical nouns" from the "critical verbs" in front of the nouns and manipulated the contextual constraints of sentences and the semantic categories of "critical nouns". In experiment 1，we used self-paced reading task to suggest that more time is spent at the anticipatory stage in support of predictive processing in strong constraint conditions. In experiment 2, we used functional magnetic resonance imaging technique to investigate the neural mechanism of predictive processing. The results of the whole brain analysis and ROI analysis showed that in the anticipatory stage, compared with the weak constraint condition, the activation of left IFG was enhanced in the two strong constraint conditions. In the integration stage, activity in left SFG/MFG/IFG left STG/MTG bilateral occipital lobe, bilateral caudate and thalamus, was decreased in the strong constraint conditions than that in the weak constraint condition. In both stages, compared with weak constraint condition and "strong constraint-building" condition, "high constraint-tool" condition had higher activation in left ITG which is associated with tool representation. Besides, compared with weak constraint condition and "strong constraint-tool" condition, "strong constraint-building" condition had higher activation in left parahippocampal gyrus, which is related to building representation. The results of the study indicate that the specific semantic features of the expected words can be pre-activated in the strong contextual constraint conditions in the anticipatory stage, and the left IFG will participate in the predictive processing. In integration stage, integration is more easily conducted in strong constraint contexts compared with the low constraint context, indicating that the left frontal and temporal lobes, bilateral occipital lobes and some subcortical regions are involved in the integrative processing.