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1、南京航空航天大学硕士学位论文 i摘 要 视觉研究是认识人脑信息处理、学习记忆和抽象思维等高级脑功能的重要途径。功能磁共振成像(fMRI)作为一种探测脑内功能活动的新手段，具有无创伤性、无放射性、较高时间和空间分辨率等诸多优势。本文利用 fMRI 技术对人脑视觉皮层功能进行研究，实现了视网膜脑图的绘制，并从脑功能水平研究了视觉对比敏感度和视觉运动觉。主要研究工作和创新之处如下： 1. 采用离心/极角刺激的实验方案和基于三维体数据的 VFS 分区法实现了对人脑视觉皮层各功能视区的描绘。实验在国内首次成功得到各受试者视觉皮层的个体化分区图，描绘出 V1- V8 等精细视区，各视区以一定的拓扑结构分布
2、于枕叶皮层。 2. 创新性地将 fMRI 视网膜脑图技术用于研究弱视对比敏感度皮层功能缺失的发生机制，比较健眼和弱视眼在视觉皮层 V1- V8 区的反应并对初、高级视皮层间的功能缺失进行回归分析。结果发现弱视患者初、高级视觉皮层均存在功能缺失，但两者之间无明显相关性。本实验方法能够精确到视皮层各功能分区的层面，使得对弱视病理机制的研究更加深入。 3. 引入组块/稳态设计的实验方案， 并将空间独立成份分析和时间相关方法相结合来研究不同活动状态下人脑视觉运动功能连通网络的变化特性。实验结果表明，静息时 V5 区的功能连通网络更广泛，且与已知的解剖连通一致；当被试接受连续视觉运动刺激时，与 V5 区
3、连通的脑区网络局限在视觉皮层，此时的网络特定于处理视觉运动这一任务。本实验方法简单有效，有利于深入理解人脑在系统水平上的动态运作方式。 关键词：功能磁共振，视网膜脑图，对比敏感度，功能连通，视觉运动 人脑视觉皮层功能的功能磁共振成像研究 ii ABSTRACT Visual research is an important approach to understand advanced functions of human brain, such as information processing, learning and memory, abstract thinking and so o
4、n. As a new technology to explore the functional activities of brain, functional magnetic resonance imaging (fMRI) has the advantages of non- invasion, non- radialization and high temporal and spatial resolution. Based on fMRI, function of human visual cortex is studied in this dissertation, retinot
5、opic mapping technique is realized and studies of contrast sensitivity and visual motion perception are conducted at the level of human brain function. The details are shown as follows: 1. Under the experimental paradigm of eccentricity/polar angle stimuli, visual areas of human cortex were outlined
6、 using VFS method based on 3D volume data set. In all subjects, V1- V8 areas were delineated clearly. The visual areas were distributed on the occipital cortex as topological frame. 2. Based on fMRI retinotopic mapping technique, visual cortical deficit of contrast sensitivity in human amlyopia was
7、studied creatively. Responses were compared between the fellow fixing and amblyopic eye in V1- V8 visual areas, the deficits in primary and secondary visual cortex were analyzed regressively. The result showed that: There were functional deficits in both primary and secondary visual cortex and no li
8、near correlations between the activation loss of striate and extra- striate cortex in amblyopes. The method can observe the cortical deficit within each retinotopic visual area, and provides a deeper insight into the amblyopia from the pathophysiologic point of view. 3. Under the block- design/stead
9、y state experimental paradigm, changes of functional connectivity network related to visual motion function in different brain activity were investigated by combing spatial independent component analysis with temporal correlation. The experiment indicated that: The functional connectivity network of
10、 V5 was more extensive and was consistent with the known anatomical connectivity during rest; when subjects were viewing motion, the network was limited in the visual cortex suggesting that V5 was acting in concert with a network 南京航空航天大学硕士学位论文 iii specific to the visual motion processing task. The
11、method is simple and efficient, and provides a deeper understanding of the dynamic working manner of human brain at the system level. Key Words: Functional Magnetic Resonance, Retinotopic Mapping, Contrast Sensitivity, Functional Connectivity, Visual Motion 南京航空航天大学硕士学位论文 vii 图、表 清 单 图 2.1 BOLD- fMR
12、I成像原理示意图 .9 图 2.2 刺激任务设计模式.10 图 2.3 基本 ICA算法矩阵表达形式示意图.13 图 2.4 视觉通路示意图.16 图 2.5 视觉皮层各视区分布.18 图 2.6 背侧与腹侧通路示意图.19 图 3.1 拓扑结构映射关系示意图.21 图 3.2 离心和极角观察方式示意图.22 图 3.3 极角刺激视觉皮层与视野拓扑映射关系示意图.23 图 3.4 垂直和水平的子午线刺激.24 图 3.5 极角和离心刺激图案.25 图 3.6 视觉皮层功能分区流程图.26 图 3.7 视觉皮层分区二维显示图.30 图 3.8 样本间视区的差异.31 图 4.2 健眼与弱视眼对比敏感度函数曲线图.41 图 4.3 一受试者各功能视区对比敏感度反应的 T 值图.42 图 4.4 健眼(黑色)与弱视眼(白色)视觉皮层各功能区的平均 T 值图.43 图 5.1 组块视觉运动刺激.50 图 5.2 功能连通性分析的流程图.51 图 5.3 视觉运动刺激激活图.53 图 5.4 静息状态下相
