| dc.description.abstract | Sentence reading requires orchestration of multiple linguistic operations including processing lexical and compositional semantics, and determining structural and grammatical relationships among words. Despite extensive investigations on the neural correlates of sentence reading, the exact computations of distinct brain regions associated with these operations remain to be elucidated. Neuropsychological and neuroimaging research in Indo-European languages has suggested involvement of a ventral stream (encompassing the anterior temporal cortex) in compositional semantics, and a dorsal stream (including the left inferior frontal gyrus) in the processing of syntax. However, whether these associations are general to all languages has been challenged by empirical findings from typologically different languages. Moreover, some domain-general factors (e.g., working memory) have been observed to affect language, particularly syntactic, processing.
The primary aim of the present dissertation is to test the predictions of the neurocognitive models of sentence processing concerning language-related brain regions in Mandarin Chinese, a head-final language with less transparent syntactic categories (i.e., less obvious verb-noun distinction) and with limited morphosyntax when compared to Indo-European languages. The secondary aim of the present dissertation is to examine whether and to what extent the correlates of syntactic processing in Chinese exhibit domain-generality.
Two FMRI experiments (Experiments 1 & 3), a self-paced reading experiment (Experiment 2) and an ERP experiment (Experiment 4) were carried out in order to explore sentential and syntactic processing in Chinese. The neuroimaging findings revealed a ventral stream spanning the posterior and anterior portions of the temporal lobe, which respond to lexical (compounding) and sentence-level (compositional semantics) integration, respectively, and a dorsal stream encompassing the left inferior frontal gyrus, which correlates with syntactic revision, and the left inferior parietal lobule, which is associated with both syntactic revision and complexity. These findings are not fully consistent with the predictions of the neurocognitive models of sentence processing. It is claimed that Chinese sentence processing is largely semantics-driven and more dependent on the ventral stream when compared to Indo-European languages.
Furthermore, it was found that when reading Chinese prenominal relative clauses, a stronger P600 effect was elicited by subject relative clauses than object relative clauses on the head noun. This finding contradicts with previous studies on processing of post-nominal relative clauses in Indo-European languages. It is claimed that a sentence processing account based on the linear distance between dependencies, rather than structural distance between syntactic nodes, can account for these findings. Moreover, while individual memory spans did not interact with most of the syntactic processing measures (reading time, BOLD signal, P600), they did modulate certain ERP correlates. Therefore, both domain-general and domain-specific verbal working memory resources underlying syntactic processing are proposed.
In conclusion, the current findings highlight language-specificity of syntactic processing, challenging sentence processing accounts which posit universal structural preferences. The findings also cast doubt on neurocognitive models which propose neural networks of sentence processing shared across languages. On the other hand, the present findings also underline both domain-specific and domain-general aspects of syntactic processing, which appears to be supplied by both domain-general and domain-specific working memory resources. | en_US |