Study Of Differences In Brain Structure And Function Between Bai-Chinese Bilinguals And Chinese Monoliguals

Purposes:Humans have a unique ability to learn more than one language. Those can speak two formal languages are called bilinguals. In the past, most scholars believe that learning two or more languages just leads to changes in brain function, and rarely mentioned that it would affect the structure of the brain. With the rapid development of neuroimaging, researchers have paid more attention on effect to cerebral microstructure of language acquisition and proficiency in recent years. This study examined the differences of gray matter and white matter between Chinese ethnic minorities (BAI) white-Chinese bilinguals and Chinese monolinguals, to identify structural differences between the Bai (Pai) minority bilinguals living in Yunnan and the Chinese monolinguals, to investigate structural plasticity and to speculate the possible structural basis in language acquisition.Materials and Methods:To test for differences in the density of grey and white matter between bilinguals and monolinguals, our researches included two parts:part1: we scanned30monolinguals who had had little or no exposure to a second language and33bilinguals, who are proficient in Bai language (L1) and Chinese (L2) by using a T1-weighted three-dimensional gradient sequence with a3.0Tesla Vision system (PHILIPS). All volunteers for this test were native speakers of comparable age and level of education. We scanned all volunteers on the same MRI scanner by a doctor who was on top of operation. We used a whole-brain unbiased objective technique, known as voxel-based morphometry (VBM), to analyze the grey matter concentration of brain and Freesurfer (http://surfer.nmr.mgh.harvard.Edu/) software to analyze cortical thickness. After that, we compared the grey matter concentration and the cortical thickness of the whole brain of the two sets, to investigate whole brain structural differences of the two groups. Part Ⅱ, we also recruited30monolinguals who had little or no exposure to a second language and33bilinguals, who are proficient in Bai language (LI) and Chinese (L2).All the volunteers are scanned by using spin echo-echo plannar imaging sequence (SE-EPI), and the data are processed and analyzed by FDT (FMRIB’s Diffusion Toolbox) and TBSS (tract-based analysis statistic, TBSS) based on FSL (www.fmrib.ox.ac.UK) software. We got FA images of two sets, then make an average FA template and extracted its contour lines (tract skeleton), and put the result on the average FA image, to compare the FA differences of the two groups.Results:voxel-based morphometry (VBM) revealed that grey matter density in the frontal gyrus (including bilateral frontal gyrus、right gyri orbitales、bilateral gyrus rectus)、left postcentral gyrus and left lenticular nucleus were greater in bilinguals than monolinguals significantly. There is no significant differences in cortical thickness and FA values between ethnic bilinguals and monolinguals.Conclusions:our study reveals structural anomalies in the frontal gyrus (including bilateral frontal gyrus、right gyri orbitales、bilateral gyrus rectus)、left postcentral gyrus and left lenticular nucleus between bilinguals and monolinguals. It demonstrates that cortex in these areas are related to second acquisition.and second language acquisition may be the key factor lead to the brain structure differences between the White-Chinese bilinguals and Chinese monolinguals.