基于磁共振成像的视觉剥夺后人脑皮层结构重塑模式研究

发布时间：2018-03-09 00:09

本文选题：盲人　切入点：结构重塑　出处：《天津医科大学》2017年硕士论文　论文类型：学位论文

【摘要】：【目的】前期研究报道长期视觉剥夺后视觉皮层发生了结构重塑,但是对枕叶视觉皮层以外的视觉信息处理通路的结构重塑关注较少。本研究的目的是探索不同失明年龄段盲人全脑皮层厚度、表面积以及体积的潜在重塑,重点关注视觉经验对枕叶视觉皮层以外脑区皮层结构重塑的影响;通过引入线性和指数模型,探讨这些盲人重塑脑区结构改变与失明年龄的内在关系,以探讨这些脑区的结构重塑的形成机制。【对象与方法】本研究对象包括不同失明年龄段的盲人与正常对照,共145人。包括先盲18例(无视觉经验),早盲30例(失明年龄为1-12岁),晚盲47例(失明年龄大于12岁),以及性别与年龄相匹配的正常对照者50例。采集所有受试者的三维T1结构像,使用Freesurfer重建每个被试的脑皮层(灰白质面和软脑膜面),计算皮层形态定量表征(厚度、表面积与体积)。首先引入一般线性模型(以脑定量表征作为因变量,分组作为自变量,年龄和性别作为无关变量回归掉),基于皮层最小单元(vertex)分析全脑各组之间脑形态定量表征的差异。将皮层结构出现明显差异的脑区作为感兴趣区,提取出这些脑区的平均脑定量表征,分别利用线性和指数模型,探讨感兴趣区内平均皮层厚度与失明年龄的线性和非线性关系。【结果】(1)与正常对照相比,先盲枕叶皮层厚度明显增加,主要位于双侧初级视觉皮层、舌回和楔叶等,而双侧颞极与内嗅皮层厚度显著减低;早盲枕叶皮层厚度未见显著改变;晚盲主要表现为枕叶皮层厚度减低,包括双侧枕下回、舌回、梭状回与左侧楔叶等。早盲与晚盲均未见显著的颞极与内嗅皮层厚度改变。(2)各亚组盲人与正常对照相比均主要表现为内侧枕叶皮层表面积减低,包括初级视觉皮层、楔叶、舌回、梭状回等脑区。其中以初级视觉皮层表面积减低最显著,而且晚盲面积减低范围最广泛。(3)各亚组盲人与正常对照相比主要表现为枕叶皮层体积减低,晚盲变化范围最广泛,早盲次之。分布范围相较皮层表面积变化而言更局限。(4)在枕叶皮层,基于感兴趣区的研究发现:先盲枕叶皮层感兴趣区的皮层厚度显著高于正常人和其它几组盲人;而皮层表面积显著低于其它组;先盲枕叶皮层体积显著高于其它盲人组,而与正常人无显著差异。早盲和晚盲枕叶皮层体积显著低于正常人。(5)在颞极和内嗅皮层,基于感兴趣区的研究发现:先盲的皮层厚度显著低于其它盲人组和正常人,而早盲和晚盲的皮层厚度与正常人无显著差异;四组之间该脑区的皮层表面积无显著差异;先盲左侧颞极的体积相比晚盲和正常人减低。(6)基于曲线拟合的结果显示:各感兴趣区的皮层厚度与失明年龄的关系使用指数模型拟合优度最佳,提示视觉经验对视觉相关皮层的结构重塑存在敏感期,具体表现为:在枕叶皮层,随着失明年龄的增加,盲人皮层厚度呈指数减低,1-2岁后失明者,盲人枕叶皮层厚度趋于稳定,与正常人相差不大;而在枕叶外的颞极和内嗅皮层,随着失明年龄的增加,盲人皮层厚度呈指数增加,2-5岁失明者,盲人皮层厚度趋于稳定。【结论】视觉剥夺后盲人不仅枕叶内视觉亚区,而且腹侧视觉通路上颞极与内嗅皮层等结构也发生了结构重塑:(1)所有盲人枕叶视觉皮层表面积普遍萎缩,提示继发于前视觉通路损害的轴突变性机制在所有盲人均发挥作用;(2)仅先盲枕叶视觉皮层增厚提示其存在关键期,是轴突变性、皮层发育及经验依赖性可塑性共同作用的结果。(3)先盲颞极和内嗅皮层变薄主要与经验依赖性可塑性机制有关。
[Abstract]:[Objective] the study reported long after visual deprivation visual cortex occurred in structural remodeling, but the occipital visual cortex outside the visual information processing pathway remodeling less attention. The purpose of this study is to explore the different ages of the blind blind the cortical thickness, surface area and potential remodeling volume, focused on the visual experience the occipital visual cortex cerebral cortex than structural remodeling; through the introduction of linear and exponential model, to explore the internal relations of these brain structure changes and remodeling of the blind blind age, the formation mechanism of structural remodeling of these brain regions. [method] the study object and the object of different ages including blind blind and normal control, a total of 145 people. 18 cases including the first blind (no visual experience), 30 cases (blind blind as early as age 1-12), 47 cases (late blind blind age more than 12 years), and gender and 50 normal subjects matched for age. The three-dimensional structure of T1 collected in all subjects like, the use of Freesurfer reconstruction of each participant and the cerebral cortex (gray matter surface and surface morphology of cortex, PIA) calculation of quantitative characterization (thickness, surface area and volume). Firstly, the general linear model (in the brain as a quantitative characterization the dependent variable grouping as independent variables, age and gender as independent variable regression, the smallest unit off) cortex (vertex) based on analysis of differences between groups of whole brain brain morphology. The quantitative characterization of cortical structures appear significantly different brain regions as region of interest, the average brain extract quantitative characterization of these brain regions, respectively, by linear and exponential model to investigate the linear and nonlinear relationships in mean cortical thickness and blind age. [results] (1) compared with normal control, the first blind occipital cortex thickness increased significantly, mainly in the bilateral The primary visual cortex, cuneus and lingual gyrus, and bilateral temporal and entorhinal cortex thickness decreased significantly; the early blind occipital cortex thickness had no significant change; late blind is mainly occipital cortex thickness reduction, including the bilateral inferior occipital gyrus, lingual gyrus, fusiform gyrus and left cuneus. Early blind and night blind showed no significant temporal and entorhinal cortex thickness change. (2) the subgroup of the blind and normal controls were mainly manifested as medial occipital cortex decreased surface area, including the primary visual cortex, cuneus, lingual gyrus, fusiform gyrus and other brain regions. The surface area of the primary visual cortex the most significant decrease, and reduce the blind area late most widely range. (3) the subgroup of the blind and normal controls were mainly occipital cortex volume decreased, the most widely varied night blind, blind early times. The distribution range of cortical surface area changes compared to more limitations. (4) in the occipital cortex based on the interest. Study on the interest region found that cortical thickness first blind occipital cortex region of interest was significantly higher than that of normal people and several other groups of blind; and the cortical surface area was significantly lower than other groups; the first blind occipital cortex volume was significantly higher than that of other blind group, but no significant difference with normal people. Early and late blind blind occipital cortex the volume was significantly lower than that of normal people. (5) in the temporal pole and the entorhinal cortex, a region of interest based on the study found: cortical thickness was significantly lower than the other first blind blind group and normal people, and there was no significant difference between early and late cortical thickness of blind blind and normal people; no significant differences in the cerebral cortex of table the area between the four groups; the first blind left temporal pole compared to the volume of normal people and reduce the blind late. (6) based on the results of curve fitting showed that the relationship between cortical thickness and blind age of each region of interest using the index model of the best model, suggesting that visual experience on visual related skin There is a sensitive period for the remodeling of the specific performance: in the occipital cortex, with increasing age of the blind, blind cortical thickness index was decreased after 1-2 years old and blind, blind occipital cortex thickness tends to be stable, and the normal people have little difference; while in the occipital lobe temporal and entorhinal cortex, with the age of the blind blind increase, cortical thickness increases exponentially, 2-5 years old and blind, blind cortical thickness tends to be stable. [Conclusion] after visual deprivation not only blind occipital Jueya optic zone, and the ventral visual pathway temporal pole and entorhinal cortex structure occurred in structural remodeling: (1) all the blind pillow leaf surface area is shrinking in the visual cortex, suggesting that secondary to anterior visual pathway impairment of axonal degeneration mechanisms play a role in all of the blind; (2) only the first blind occipital visual cortex thickening suggesting there is a critical period, is axonal degeneration, cortical development and experience dependent The result of the common action of sexual plasticity. (3) the thinning of the blind temporal and the olfactory cortex is mainly related to the mechanism of empirical dependence plasticity.

【学位授予单位】：天津医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R445.2;R338

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