| Multiple ethnic groups live in China's north-western Xinjiang Uygur Autonomous Region with Uygurs being the largest among the minorities. People noticed that many ethnic minorities not only master their national language, but also be skilled in Chinese, English and so on. They show stronger learning ability than the Han's. Thus we ask, do monolingual and bilingual brains process language similarly or dissimilarly, and is this affected by the language context? Using an innovative brain imaging technology, the blood oxygen levels dependent technology of magnetic resonance imaging (BOLD-fMRI), we want to find out differences in activated brain areas during semantic judgment tasks and nerve structure after visual stimulation with Uygur and Chinese words. This technique not only show the language function activation's size, scope, but also can display the exactly activation area.Objective:1) We discussed the BOLD-fMRI reliability and feasibility; 2) We investigated how Uygur monolinguals process semantic information, to value the increase of MR signal in the functional cortical regions related to Uygur using BOLD-fMRI technique, whether the normal Uygur brain has the specific language function area in accepting the uygur task; 3) Functional magnetic resonance imaging was used to compare cortical organization of the first (L1, Uygur) and second (L2, Chinese) languages in early bilingual subjects in Xinjiang; 4) Using fMRI to study whether there is a common or a distinct neural semantic system and active voxels for native language (L1; Uygur) and second language (L2; Chinese) in late bilingual subjects in Xinjiang; 5) It is generally accepted that the presence of a second language (L2) has an impact on the neuronal substrates build up and used for language processing. we tested the hypothesis that the age of L2 acquisition has an effect on the cortical representation during semantic tasks performed.Methods:1)11 healthy right-handed Han monolinguals, completed a semantic judgment task in Chinese words; 2) 32 right-handed Uygur monolinguals, had nothing wrong with their brain, visually stimulated with monosyllabic notional Uygur language words; 3) 18 early exposed, highly proficient Uygur-Chinese bilinguals completed a semantic judgment task in Chinese and Uygur words; 4) 21 healthy right-handed late exposed Uygur-Chinese individuals participated in this study. Those two groups after visually stimulated with monosy-llabic notional Uygur language words, they were asked to perform semantic judgment tasks with visual stimulation of single Chinese characters during fMRI imaging; 5) Two groups of fluent Uygur-Chinese bilingual subjects (18 early and 21 later learners of L2), completed a semantic judgment task in Chinese words. All Uygur bilinguals came from Central Dialect regions. The functional images of brain were acquired with a PHILIPS Achieva nova dual 1.5 MRI. Individual and group functional datasets were analyzed using Statistical Parametric Mapping software (SPM5; P<0.001 with a 5-voxel spatial extent threshold) and overlaid on T1-weighted anatomic images normalized to a standard (Montreal Neurology Institute) space. Analysis of laterality indices derived from voxel counts in regions of interest (ROIs).Resulte:l) In the Han monolinguals, we observed activted areas included left middle frontal gyrus,left inferior frontal gyrus,left middle temporal gyrus,left inferior parietal lobuleand right middle occipital gyrus; 2) In the Uygur monolinguals context several cortical and regions were activated. Activated areas included:left superior /inferior parietal lobule, left precuneus, right superior temporal gyrus, right lingual gyrus, bilateral middle/inferior frontal gyrus, precentral gyrus, bilateral middle temporal gyrus, bilateral occipital middle gyrus, fusiform gyrus and some cerebellar areas were significantly activated in semantic judgment (P< 0.001). The activation volume in left hemisphere was larger than that in right hemisphere; 3) In the early bilingual context, we observed distinct regions of activation for Uyghur in the Left middle temporal gyrus, right superior temporal gyrus, But activation in the bilateral superior frontal gyrus, right medial frontal gyrus, right superior and inferior parietal lobules only induced by Chinese stimulation. Areas were significantly activation in the left cerebral hemisphere in both Uygur and Chinese language tasks; 4) In the late bilingual subjects, study showed specific activation of the bilateral middle temporal gyrus and right lingual gyrus when Uygur language were read. Bilateral medial frontal gyrus and left occipital inferior gyrus, were activated with L2 but L1. Declive was activated with semantic processitn of both language stimulations. Activation volume was greater in left brain hemisphere than the right hemisphere during both language tasks; 5) In both late and early bilingual subjects who performed high frequency Chinese, we discovered both two groups activted areas included bilateral middle and inferior frontal gyri, precentral gyrus, the right medial frontal gyrus, bilateral parietal lobule, bilateral fusiform gyrus and some occipital areas. Early bilinguals were aslo activted bilateral superior frontal gyrus and insular lobe.Coaclusion:1) BOLD-fMRI is a good method in language research; 2) Many areas of cortex and subcoitex are involved in Uygur character semantic judgment, the dominant hemisphere for Uygur was left hemisphere; 3) In the early bilingual context, the neural networks utilized for semantic language processing in the nonnative language may not be as similar as those in the primary language. Both two language tasks demonstrated left cerebral dominance. There was not obviously difference between Uygur and Chinese tasks in lateralization index (P>0.05); 4) In the late bilingual subjects, our study showed some activated brain areas overlap when subjects were stimulated both with Chinese and Uygur languages, while some activated brain areas were language specific. The dominant hemisphere for both languages were left hemisphere. Lateraliza-tion index of L1 and L2 had no statistical differences (P>0.05); 5) Early and late fluent bilinguals nearly shared the common functional neuroanatomy in L2. Language proficiency may affect the activated areas and active voxels, but age only affected the activated areas. Through focusing on native Uygur speakers in this research, we hope to enrich our understanding of the Uygur language associated brain function, thus to help surgery planning and recovery monitoring of brain tumor or brain injury patients among the Uygur population. |
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