| 其他摘要 | Language and social cognition are closely associated with each other in theevolution of human brain and in the development of individual cognition. It has beenfound that the neural correlations of language and social cognition overlap in tworegions of the left lateral temporal lobe, i.e., left lateral anterior temporal lobe (LlATL)and left temporoparietal junction (LTPJ). Some researchers have argured that theseregions are specific to langauge processing and possibly engage in sentence-levelsemantic encoding, which was referred to as “sentence processing hypothesis” inpresent. Some other researchers have argured that these areas are specific to socialcognition, e.g., theory of mind or representing social concepts.
In this paper, we proposed a “social semantics working memroy” hypothesis toexplain the functions of these regions. This hypothesis propoased that LlATL andLTPJ are parts of social semantics working memory system, with functions ofmaintaining, accumulating, and integrating social semantics. This hypothesis canexplain the findings about LlATL and LTPJ in various kinds of social cognition tasks.In previous language studies, general sentence processing might be confounded withthe accumulation and integration of social semantics, which suggested that theirfindings can be explained by social semantic working memory hypothesis. Therefore,in present study, sentence processing hypothesis is the main competing one to socialsemantic working memory hypothesis. We conducted a seris of studies to test thepredictions of above two hypotheses, including: 1) whether the sentence processingeffect in the LlATL and LTPJ depends on social semantic accumulation; 2) whetheractivation of the LlATL and LTPJ depends on social processing rather than languageprocessing; 3), during processing more than one sentence, whether activation of theLlATL and LTPJ can increases with number of sentences or with amount of socialsemantic information; 4) whether LlATL and LTPJ can maintain the previous socialsemantics after the sentence input and during processing new sentence; 5) whether the LlATL and LTPJ integrate social semantics between sentences. We conducted fourstudies (including seven experiments in total) to examine these predictions.
Study 1 investigated the effects of social semantic richness on the sentenceprocessing in which the linguistic hierarchy (sentence/wordlist) and social semanticrichness (high-social/nonsocial) were simultaneously manipulated. In high socialcondition, semantics of experimental materials were related to interpersonal activities,while in nonsocial condition, no animation was involved. Results showed that theLlATL and LTPJ only showed the sentence processing effect during the processing ofsentences with high social semantic richness. Moreover, LlATL and LTPJ showstronger resting-state functional connectivities with social semantic network thansentence processing network. Study 2 investigated performance of LlATL and LTPJin continuous sentence processing, by using a delayed response task and a ‘mentalportrait’ task. In the former task, number of sentences to be encoded (2/4) and socialsemantic richness of sentences were manipulated. Brain activation in LlATL andLTPJ decreased with number of sentences but increased with the amount of socialsemantic information. In addition, they showed social semantic effects in themaintenance stage wherein no sentence is presented. In the latter task, participantsneed to read two sentences in turn. In high social condition, sentences described twodifferent personalities, while in low social condition, sentences described twodifferent facial features. Following the sentences, two faces were presented, andparticipants were asked to decide which face coincided more with description of thetwo sentences. It was found that patterns of brain activation of LlATL and LTPJ whenprocessing the current sentence maintained the social semantics of last sentence.Study 3 found that the preferences of LlATL and LTPJ to social stimulus did notdepend on language input. Study 4 investigated whether the LlATL and LTPJintegrate social semantics during sentence and narrative comprehension usingparametric analysis and social semantic rating at multiple lingustic levels. It wasshowed that the LlATL and LTPJ engae in social semantic integration during sentencecomprehension, and LlATL may further engage in social semantic integration innarratives.
In conclusion, we investigated the functions of LlATL and LTPJ from variousperspectives. Our results supported the “social semantics working memroy”hypothesis rather than sentence processing hypothesis, indicating that the LlATL andLTPJ are sensitive to maintaining, accumulating, and integrating social semanticsrather than sentence processing. The present study provides a novel explaination andargument for the function of the LlATL and LTPJ, sheding new lights on therelationship between language processing and social processing in brain. |
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