基于低频振幅算法的屈光参差性弱视自发脑活动研究

目的基于低频振幅(amplitude of low frequency fluctuation,ALFF)算法分析屈光参差性弱视和正常对照组的功能性磁共振成像(functional magnetic resonance imaging,f MRI)图像数据,对比揭示弱视患者脑部自发活动的异常,以及这些异常与弱视视力损失的相关性。方法在闭眼静息条件下采集22例弱视成年人和21例正常对照组f MRI数据,对f MRI数据进行预处理,计算每个被试脑区的ALFF值。应用双样本t检验对ALFF结果进行组间分析,采用皮尔森分析弱视不同脑区的ALFF与其损伤的相关程度。结果在屈光参差性成人弱视与正常组有显著性差异的脑区中,脑部自发活动增加的脑区主要分布在颞下回、颞上回、枕叶等区域,脑部自发活动降低的脑区主要分别在小脑后叶、额下回、额上回等区域。首次发现小脑后叶、楔回、枕叶、颞上回和额叶等区域脑区自发活动与弱视损伤有显著相关性。结论基于低频振幅的静息态磁共振分析是有效的非侵入式脑区同步性异常研究方法,能够反映屈光参差性弱视自发脑部活动脑区异常表现,这些同步性异常表现与视力损失程度有较强的相关性,这些结果对于弱视致病机制模型研究和提出新的治疗方法都有重要启发。     

基于功能连接算法的斜视性弱视儿童静息态功能磁共振成像的研究

目的探索斜视性弱视儿童脑功能区及其功能连接的改变,揭示斜视性弱视的发生与脑功能改变的相关性。方法在静息态下采集22位斜视性弱视儿童和10名健康儿童脑功能磁共振图像,利用DPARSF软件计算全脑与ROI功能区的连接系数,并应用t检验对实验组和健康对照组进行组内和组间功能连接系数分析。结果发现斜视性弱视儿童部分脑功能连接低于正常对照组的相应脑区连接,这些功能区主要分布于枕叶、颞叶、小脑后叶、顶叶、额叶、扣带回等脑区。结论基于静息态的f MRI的脑功能连接算法可以反映斜视性弱视儿童视皮层的变化和多脑区神经活动的变化。     

癫痫患者默认网络的静息态功能磁共振成像研究

目的:分析癫痫患者静息态fMRI下默认网络及其潜在结构的变化.方法:对15名临床诊断为原发全身强直痉挛癫痫患者和20名正常志愿者静息态时的fMRI数据进行独立成分分析,依据空间最佳匹配原则挑选独立成分,研究正常被试和癫痫患者的默认网络差异,并选定默认网络中11个脑区构建功能连接网络,运用图论和聚类方法探讨其潜在结构的改变.结果:与正常对照组相比,患者组默认网络的脑区激活普遍下降,功能连接网络发生明显变化,且整个网络呈现出混乱的层次化结构.结论:静息态下癫痫患者的默认网络及潜在的层次化结构发生异常.     

正常脑老化中静息态功能磁共振成像功能连接的研究进展

【摘要】静息态功能磁共振成像（fMRI）作为一种不需要任务刺激就能呈现功能脑影像的技术手段,在临床上被广泛应 用。基于静息态fMRI的静息态功能连接（RSFC）,作为一种重要的计算机辅助分析法,能够度量不同脑区的脑功能连接 强度,对脑老化相关的神经科学领域的研究具有重要意义。本文介绍了功能连接的基本概念,总结了近年来脑老化相关 的人脑功能连接的研究成果,最后提出了该研究领域存在的问题及未来的研究方向。     

基于独立成分分析和时间相关分析的脑功能连通研究方法[英文]

目的:利用静息状态功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,提出联合独立成分分析(independent component analysis,ICA)和时间相关分析的人脑功能连通性研究方法。方法:首先采用空间ICA定位任务激活的脑区;然后选择一个激活区作为感兴趣区域(region of interest,ROI),采用时间相关分析方法检测静息状态大脑特定皮层的功能连通性,并通过检测人脑运动皮层的功能连通性验证方法的有效性。结果:大脑运动皮层功能连通网络包括初级运动区、辅助运动区、初级感觉皮层、背侧前运动区和后顶骨体觉区。实验结果表明,静息状态下,时间相关分析检测到的运动皮层的功能连通网络与已知的解剖连通相一致。结论:利用静息fMRI,结合空间ICA和时间相关分析方法,检测了静息时人脑运动皮层的功能连通网络,为脑区间功能连通的研究提供了一种简便的、无损的、有效的研究方法。     

青少年肌阵挛癫痫患者的大尺度脑网络研究

采用静息态功能性磁共振成像(rs-fMRI)数据探究青少年肌阵挛癫痫(JME)患者大尺度脑网络的变化。采集17例JME患者和15名正常志愿者的脑部静息态功能磁共振成像数据,两组均使用偏相关系数构建静息态脑网络。分别计算JME患者组与正常对照组的阈值,构建二值化脑网络。计算两组被试各个脑区的介数值,采用双样本t检验对比两组脑网络介数值的差异(Bonferroni 校正,P<0.01),找出介数值发生显著变化脑区。结果表明,偏相关系数构造的脑网络具有小世界属性。JME患者组脑网络中脑区的介数值相比正常对照组有显著性差异。与正常对照组相比,JME患者组介数值显著降低的脑区有2个,介数值显著升高的脑区有17个。其中属于默认模式网络(DMN)的脑区有8个,属于突显网络(SN)的脑区有5个。JME患者组介数值显著降低的脑区有右侧中央旁小叶和右侧后扣带回,介数值显著增高脑区主要是右侧背外侧额上回、左侧枕中回、右侧楔前叶和右侧舌回等。JME患者介数值发生显著改变的脑区主要属于默认模式网络和突显网络。可以推断出默认模式网络和突显网络内部脑区间连接发生改变,信息传递产生变化。由此可能会导致JME患者大脑功能发生改变,造成患者的认知能力与执行能力等功能受损。     

原发性失眠患者大脑额顶网络的异常功能连接

目的:利用功能磁共振成像技术研究原发性失眠患者大脑异常功能连接,及其与病程和临床指标的相关性。方法:采集40例原发性失眠患者及35例在年龄、性别和受教育程度均匹配的健康被试在静息状态下的功能磁共振图像,从静息态功能磁共振数据中利用独立成分分析确定出10个静息态网络。利用FSL非参数置换检验进行双回归分析,从而检测10个静息态网络中基于体素的组间差异。利用皮尔逊相关分析检测异常的功能连接与各项临床指标的关系。结果:原发性失眠患者与正常对照组相比,在静息状态下大脑右侧额顶网络中的顶上回和额上回与网络内其他脑区的功能连接出现降低。进一步的相关分析发现,原发性失眠患者中异常的功能连接与临床指标无相关性。结论:证明在静息状态下原发性失眠患者大脑右侧额顶网络功能连接出现异常。本结果有利于理解原发性失眠患者大脑神经活动的改变。     

基于fMRI数据的静息脑功能连接

目的:应用功能磁共振成像数据,对静息状态下大脑视觉系统功能连接模式[1]进行考证,并对不同状态下人脑视觉功能连接网络的变化[2,3]情况进行了研究。方法:基于脑区局部同一性[4],测量出一给定体素的时间序列与全脑其他体素时间序列的相似性。我们分别采集了视觉任务和静止两种状态下的功能磁共振成像数据,先是用K-均值的聚类方法[5,6]对视觉任务状态下的功能磁共振成像数据进行分析,做出分类图。然后通过分类图找到感兴趣种子区,平均种子区中各个体素的时间响应曲线,利用这个时间序列曲线与全脑体素作互相关分析[7],得出视觉任务下的全脑功能连接图,再把同样的感兴趣种子区域定位到静息状态下的脑区中用种子相关分析方法,作出静息状态下全脑视觉系统功能连接的网络模式及分布规律。结果:分别得到了视觉任务状态下和静息状态下以相同种子区为中心的功能连接网络图。结论:无论是在静息状态还是在任务状态下,大脑视觉系统各脑区之间的确存在密切的功能连接,而且状态不同所得到的视觉功能连接网络也不相同。     

注意缺陷多动障碍儿童动态功能连接的功能磁共振成像研究

目的:探索注意缺陷多动障碍儿童静态以及动态功能连接的异常。方法:收集智商高于80的6～16岁符合DSM-IV诊断的注意缺陷多动障碍儿童97例(男78例,女19例)和年龄匹配的正常对照儿童74例(男45例,女29例)的静息态功能磁共振成像数据,比较两组全脑静态功能连接和动态功能连接指标。结果:注意缺陷多动障碍组的静态功能连接与正常对照组的差异无统计学意义(P>0.05),注意缺陷多动障碍组腹外侧前额叶与全脑其他脑区功能连接的模式变异性大于正常对照组[(0.65±0.07)%vs.(0.60±0.08)%,P<0.01]。结论:动态分析提示腹外侧前额叶是注意缺陷多动障碍的关键脑区,为理解疾病的脑机制提供可能的新视角。     

重性抑郁症的静息态功能磁共振成像低频振幅研究

应用功能磁共振成像(fMRI)低频振幅(ALFF)方法研究重性抑郁症(MDD)静息状态下脑活动。本研究利用GE公司生产的Signa3.0TMRI对MDD组(13人)和正常对照(HC)组(14人)均做静息态fMRI扫描。应用双样本t检验计算并对比两组ALFF改变的脑区。结果发现静息状态下,MDD组患者右内侧前额叶ALFF值较HC组增高,差异有统计学意义(P0.001);MDD组患者左侧顶叶ALFF值较HC组减少,差异有统计学意义(P0.001)。由此可以得知MDD患者静息态下右内侧前额叶及左侧顶叶脑功能区ALFF值产生显著变化。     

Relationship of visual cortex function and visual acuity in anisometropic amblyopic children

Purpose: To detect the functional deficit of the visual cortex in anisometropic amblyopia children using functional magnetic resonance imaging (fMRI) technique, and investigate the relationship between visual acuity and visual cortex function.Methods: Blood oxygenation level-dependent fMRI (BOLD-fMRI) was performed in ten monocular anisometropic amblyopia children and ten normal controls. fMRI images were acquired in two runs with visual stimulation delivered separately through the sound and amblyopic eyes. Measurements were performed in cortical activation of striate and extrastriate areas at the occipital lobe. The relationship between cortex function and visual acuity was analyzed by Pearson partial analysis.Results: The activation areas of both the striate and extrastriate cortices in the amblyopic eyes were significantly lower than that of the sound fellow eyes. No relationship was found between the striate and extrastriate cortex activation. No relationship was found between the visual cortical activation of striate, extrastriate areas and visual acuity of anisometropic amblyopes.Conclusions: BOLD-fMRI revealed the independent striate and extrastriate cortical deficits in anisometropic amblyopes. In addition, the visual acuity lesion and the striate and extrastriate cortical deficits were not parallel, and results of fMRI examination have much potential value in the evaluation of amblyopia.     

高阶像差在远视儿童屈光参差性弱视中的评价

使用美国ZYWAVEⅡ像差分析仪对54例屈光参差性远视弱视儿童共108只眼进行像差检查,就像差均方根(RMS)分布情况进行统计分析研究,观察各类高阶像差(HOAs)分布、屈光参差性弱视程度与HOAs的关系。所有患儿弱视眼的总HOAs、总彗差(TC)、总球差(TSA)、总5阶像差(RMS5)的均方根逐阶递减。弱视眼各阶像差均方根值均大于对测眼,但无统计学差异。弱视眼随弱视程度增大,TC、TSA和RMA5呈递增趋势。弱视眼TSA与屈光参差度正相关。HOAs可能在屈光参差性弱视的发展中起了一定作用,但不是主要影响因素。     

Measurement of spontaneous signal fluctuations in fMRI: adult age differences in intrinsic functional connectivity

Functional connectivity (FC) reflects the coherence of spontaneous, low-frequency fluctuations in functional magnetic resonance imaging (fMRI) data. We report a behavior-based connectivity analysis method, in which whole-brain data are used to identify behaviorally relevant, intrinsic FC networks. Nineteen younger adults (20–28 years) and 19 healthy, older adults (63–78 years) were assessed with fMRI and diffusion tensor imaging (DTI). Results indicated that FC involving a distributed network of brain regions, particularly the inferior frontal gyri, exhibited age-related change in the correlation with perceptual-motor speed (choice reaction time; RT). No relation between FC and RT was evident for younger adults, whereas older adults exhibited a significant age-related slowing of perceptual-motor speed, which was mediated by decreasing FC. Older adults’ FC values were in turn associated positively with white matter integrity (from DTI) within the genu of the corpus callosum. The developed FC analysis illustrates the value of identifying connectivity by combining structural, functional, and behavioral data.     

Independent Sources of Spontaneous BOLD Fluctuation Along the Visual Pathway

In resting-state functional magnetic resonance imaging (fMRI) experiments, correlation analysis can be used to identify clusters of cortical regions that may be functionally connected. Although such functional connectivity is often assumed to reflect cortico-cortical connections, a potential confound is the contribution of subcortical brain regions, many of which have strong anatomical connectivity to cortical regions and may also enable cortico-cortical interactions through trans-thalamic pathways. To investigate this, we performed resting state fMRI of the human visual system, including cortical regions and subcortical nuclei of the pulvinar and lateral geniculate. Regression analysis was used to investigate the dependence of the measured inter-regional correlations upon afferents from specific retinal, thalamic and cortical regions as well as systemic global signal fluctuation. A high level of inter-hemispheric correlation (cc = 0.95) was found in the visual cortex that could not be explained by activity in the subcortical nuclei investigated; in addition a relatively low level of inter-hemispheric correlation (cc = 0.39–0.42) was found in vision-related thalamic nuclei that could not be explained by direct anatomical connections or their cortical inputs. These findings suggest that spontaneous fMRI signal correlations within the human visual system originate from a mixture of independent signal sources that may be transmitted through thalamo-cortical, cortico-thalamic, and cortico-cortical connections either trans-callosal or trans-thalamic in origin. Our findings thus call for more cautious interpretation of resting state functional connectivity in terms of any single type of anatomical connectivity.     

Detecting Functional Connectivity in fMRI Using PCA and Regression Analysis

A fMRI connectivity analysis approach combining principal component analysis (PCA) and regression analysis is proposed to detect functional connectivity between the brain regions. By first using PCA to identify clusters within the vectors of fMRI time series, more energy and information features in the signal can be maintained than using averaged values from brain regions of interest. Then, regression analysis can be applied to the extracted principal components in order to further investigate functional connectivity. Finally, t-test is applied and the patterns with t-values lager than a threshold are considered as functional connectivity mappings. The validity and reliability of the presented method were demonstrated with both simulated data and human fMRI data obtained during behavioral task and resting state. Compared to the conventional functional connectivity methods such as average signal based correlation analysis, independent component analysis (ICA) and PCA, the proposed method achieves competitive performance with greater accuracy and true positive rate (TPR). Furthermore, the ‘default mode’ and motor network results of resting-state fMRI data indicate that using PCA may improve upon application of existing regression analysis methods in study of human brain functional connectivity.     

Binocularity and spatial frequency dependence of calcarine activation in two types of amblyopia

OBJECTIVE AND BACKGROUND: Strabismus and anisometropia early in life frequently causes monocular amblyopia. Activation of the visual cortex is compared between the two types of amblyopia to elucidate differences in the pathogenetic mechanism of the disease. METHODS: Using an EPI gradient echo sequence in 1.5T MRI, calcarine activation by monocular viewing of checkerboard patterns with reversal was examined in terms of binocularity of the activation and dependence on the spatial frequency of the stimuli. RESULTS: First, the proportion of voxels activated by both normal and amblyopic eye monocular stimulations is lower in the strabismic group than in the anisometropic group. Second, the activation by higher-spatial-frequency stimuli is reduced in the anisometropic group, but not in the strabismic group. CONCLUSIONS: These findings from the human visual cortex are consistent with the view proposed based on animal research that the loss of binocular interaction and the undersampling of high-spatial-frequency components of visual stimuli are each one of the underlying changes in strabismic and anisometropic amblyopia, respectively.     

Aging influence on functional connectivity of the motor network in the resting state

We used functional MRI (fMRI) to study the aging influence on functional connectivity of the motor network in the resting state. A network model based on graph theory was used to measure functional connectivity. The total connectivity degree of each region within the motor network was calculated and compared between aged and young groups. We found that the pattern of functional connectivity was changed in aged subjects, including a significant decrease in the functional connectivity degree of the right cingulate motor area and left premotor area compared to young subjects. Our study demonstrates that normal aging modulates the functional connectivity of motor network in the resting state. We postulate that this abnormal functional connectivity of motor network in the baseline state is an important reason contributing to the deteriorated motor ability in aged subjects.     

慢性失眠患者大脑蓝斑的异常静息态功能连接

目的:利用功能连接方法观察慢性失眠患者静息态下蓝斑的异常功能连接。方法:采集49例慢性失眠患者以及47例性别年龄和受教育程度相匹配的健康对照组的功能磁共振图像,以蓝斑为感兴趣区域,与全脑其他体素进行功能连接分析,得到两组之间功能连接的差异脑区,再对异常连接脑区的功能连接值与临床量表分数做相关分析。结果:与对照组相比,慢性失眠患者蓝斑与右楔前叶皮质、右后扣带回皮质、左颞中回皮质、左距状沟周围皮质、右眶部额上回皮质之间的功能连接增强（P<0.05, FDR校正）,并且蓝斑与左颞中回皮质之间功能连接值与抑郁自评量表呈正相关（P=0.021）。结论:慢性失眠患者蓝斑与多个脑区（主要是默认模式网络）出现的异常功能连接,可能有助于更好地理解慢性失眠的神经生物学机制,可能为失眠的高度唤醒假说提供新的影像学证据。