| How to product speech and memorize vocabulary for bilinguals is a hot topic for the moment in brain imaging studies. We utilized fMRI to research the mechanisms of speech production and vocabulary memory for bilinguals.In the first study,we aimed to address the brain mechanisms of speech production in bilinguals and investigate the activation coordinates and the signal intensity of the left inferior frontal gyrus in processing Cantonese dialect and Mandarin of bilingual and explore . 12 college students whose native language was Cantonese dialect were scanned with fMRI when they performed the picture naming task with the black and white line drawings. The results showed that Cantonese dialect and Mandarin both activated the left inferior frontal gyrus, the right middle occipital gyrus and right precuneus. The additional areas activated by Cantonese were right superior frontal gyrus, right inferior parietal lobe and the left precuneus. Mandarin activated the left culmen, left cingulate gyrus, left superior frontal gyrus and left supramarginal gyrus additionally. The ROI of left inferior frontal gyrus was found that Cantonese dialect activated the left ventrolateral prefrontal cortex (BA47) and dorsolateral prefrontal cortex (BA9), while Mandarin only activated the dorsolateral cortex (BA9). The activation volume of Cantonese dialect was greater than Mandarin. The results suggest that bilinguals have common neural mechanisms when producing native (L1) and second language (L2), but also have their own specific nerve tissues.. the processing of L1 and L2 are located in different spatial distribution in the left inferior frontal gyrus.More importantly,in the second study,we explored the brain machining differences when processing the two tasks: storage and extraction, according to the brain activation for the English words and Chinese performing memory storage and recognition. Adopt the classical experimentation model—"Learn-- recognition", 8 undergraduates receive the examination that learning and recognizing of English and Chinese, MRI data collection, AFNI software pretreatment, multi-component regression and the language discrepancy for ANOVA group Analysis & Statistic. The Result showed that the brain section discrepancy that Chinese recognition minus English recognition are regarded as Right cerebellum,Left inferior parietal lobule,Left middle temporal gyrus. There is no brain discrepancy that"Chinese learning memory"minus"English learning recognize"in the horizontal level- 0.05. The 8 experimental students'average capability on learning and memory are activated: Chinese can activate Left Culmen,Right lingual gyrus,Left superior parietal lobule; English can activate Left Fusiform Gyrus,Right lingual gyrus,Left Superior Parietal Lobule,Right Culmen. Recognition activation section: the brain activations for English and Chinese are entirely different, Chinese recognition activated Right Nodule,Right Superior/middle Frontal Gyrus,Left superior parietal lobule,Right caudate nucleus and Right superior parietal lobule; English Recognition activated Right Lingual Gyrus,Right Cingulate Gyrus,Left inferior parietal lobule. The results revealed differences existed in bilingual brain mechanisms in different stages of the memory processing. Except for the commonly considered that frontal lobe and parietal lobe participated in the brain activation on memory, there is minor difference for English and Chinese on processing storage, but contrarily when processing extraction. Chinese has a more participated brain activation compared with English, it indicated that: one is that Chinese is more difficult to memory than English, it will cost more brain resource for extraction; the other is because of more brain element participated, the accuracy for memory enhanced well.In summary, the study indicates that bilinguals processing the memory and word generation in mother language and second language share the same neural mechanisms, as well as specific processing brain areas. We tend to the notion that the brain represents native /second language based on their specific neural network model, rather than locating in certain specific brain regions. The results play an important role in understanding brain mechanisms of the memory and production in native and second language. |
