Syntactic deficits in aphasia and brain modeling of syntactic processing

点击翻译按钮获取中文摘要

The purpose of the present research is to investigate the syntactic processing in the brain through a series lesion-deficit correlational studies with agrammatic aphasics and noninvasive brain imaging techniques such as Magnetoencephalography (MEF). We found the following three main results. First, a theoretical distinction between the lexicon and syntax is supported by the data of agrammatic aphasics' better performance on lexical causatives than the syntactic -sase causatives. An MEG investigation of the processing of sentences with selectional restriction and the wh-interrogatve sentences demonstrates the neural generator of wh-movement, a type of syntactic computation, in the vicinity of Broca's area and that of the semantic processing in the inferior part of the left temporal lobe. Second, agrammatic aphasics' performance on the processing of long- and middle-scrambling sentences in Japanese shows that the existence of a trace, or a movement operation, but not the distance between the moved element and its trace, is a crucial factor in interpreting the meaning of the sentences. Third, an MEG study of scrambled sentences shows that the activities are greater in the scrambled sentences than in the canonical sentences in the prefrontal cortex and the temporo-parietal cortex, suggesting that these areas serve as a memory storage when processing demands increase. Activities are also found in the anterior temporal cortex in the early time range, irrespective of the sentence type, suggesting that this area serves as the processing of syntactic computations in grammatically correct sentences. As a whole, these studies indicate that the processing of scrambled sentences, which has dislocated phrase from its original position, is supported by various cortical areas.