静息态脑区的活动特征研究

静息态脑区的活动处于一种相对稳定的状态。但是,静息态机能性磁共振成像(functional Magnetic Resonance Imaging,fMRI)实验中,被试者可能会受到各种噪声的影响,因此,统计分析所得到的静息态脑区的活动强度和体素数都可能受此影响。为了更进一步研究静息态脑区的活动特点,分别对16名被试采集了8′14″的静息态fMRI数据,将这些数据按照时间等分为5个部分,对每个部分分别采用低频振幅方法进行分析。实验结果显示:楔前叶和后扣带皮层包含活动体素的个数随时间变化较小,处于一种相对稳定的状态;额内侧皮层和顶下小叶中活动体素个数随时间变化差异较大,处于不是很稳定的状态。实验结果表明,静息态脑区中,楔前叶和后扣带皮层对于外界噪声的干扰不敏感,额内侧皮层和顶下小叶对于外界噪声比较敏感。     

磁共振成象新进展

磁共振成象(MRI)已经成为生命科学研究和医疗诊断的有力手段，因此荣获2003年诺贝尔生理学或医学奖．文章概述了磁共振成象的新近进展，包括医疗成象、脑功能成象、显微成象、活体磁共振波谱等方面．     

基于粒子群-支持向量机的时间序列分类诊断模型

构建一种基于粒子群算法-支持向量机(PSO-SVM)的磁共振功能成像(fMRI)时间序列分类诊断模型,通过针对脑区多维时间序列数据的深层次分析实现病症患者和健康者的准确判断与区分,为面向fMRI时间序列数据的病症诊断和预测提供有效科学依据.该方法在以下4个方面不同于其他已有相关研究工作:(1)构建基于自回归模型的脑区多维时间序列数据特征表示;(2)构建基于支持向量机模型的脑区多维时间序列数据分类机制;(3)构建基于粒子群算法的分类学习参数寻优策略;(4)建立融合上述特征表示、优化分类与参数优选模式的fMRI时间序列数据分类诊断模型.通过以精神抑郁症作为实证分析的具体案例,所提出分类诊断模型已取得良好实验效果,展示出其有效性与合理性.     

Flexible statistical modelling detects clinical functional magnetic resonance imaging activation in partially compliant subjects

Clinical functional magnetic resonance imaging (fMRI) occasionally fails to detect significant activation, often due to variability in task performance. The present study seeks to test whether a more flexible statistical analysis can better detect activation, by accounting for variance associated with variable compliance to the task over time. Experimental results and simulated data both confirm that even at 80% compliance to the task, such a flexible model outperforms standard statistical analysis when assessed using the extent of activation (experimental data), goodness of fit (experimental data), and area under the operator characteristic curve (simulated data). Furthermore, retrospective examination of 14 clinical fMRI examinations reveals that in patients where the standard statistical approach yields activation, there is a measurable gain in model performance in adopting the flexible statistical model, with little or no penalty in lost sensitivity. This indicates that a flexible model should be considered, particularly for clinical patients who may have difficulty complying fully with the study task.     

The bilingual brain: Flexibility and control in the human cortex

The goal of the present review is to discuss recent cognitive neuroscientific findings concerning bilingualism. Three interrelated questions about the bilingual brain are addressed: How are multiple languages represented in the brain? how are languages controlled in the brain? and what are the real-world implications of experience with multiple languages? The review is based on neuroimaging research findings about the nature of bilingual processing, namely, how the brain adapts to accommodate multiple languages in the bilingual brain and to control which language should be used, and when. We also address how this adaptation results in differences observed in the general cognition of bilingual individuals. General implications for models of human learning, plasticity, and cognitive control are discussed.     

以功能性核磁共振造影初探10Hz调制激光针灸刺激所引发人类大脑皮质的活化现象(英文)

使用10 Hz调制的低功率激光针灸刺激探究大脑皮质反应.以功能性核磁共振造影技术探讨当激光针灸刺激左脚涌泉穴(K1)时,大脑可能产生的反应机制.研究发现调制激光针灸所引发显著的大脑活化反应,包括右额叶中央前回、右额叶上回、左额叶中央前回、左顶叶中央后回、左侧下部顶叶、左小脑舌前叶、左海马旁回和左小脑山顶等区域.安慰剂组实验并没有发现在脑部有任何活化反应,大多数反应区域所涉及功能与记忆、注意力及自我意识等有关联.结果显示出调制激光针灸的大脑血液动力学反应,并隐含此反应机制不只是依据传入感觉信息处理,而且还有着随外部刺激的变化而有所改变的血液动力学性质.     

5HTTLPR predicts left fusiform gyrus activation to positive emotional stimuli

This study was designed to replicate and extend past research examining the impact of the serotonin transporter gene-linked polymorphic region (5HTTLPR) on neural activation during emotional processing. Six women with at least one short allele were compared to six age-matched women with long/long alleles of the 5HTTLPR. Participants were shown 36 positive and 36 negative slides from the International Affective Picture Set, while functional images were acquired using a 4-T magnetic resonance imaging scanner. Although we were unable to replicate past research demonstrating relatively increased amygdala activation among individuals with an "s" allele to negative stimuli, women with an s allele evidenced decreased left fusiform gyrus activation to positive emotional stimuli (as expected). We suggest that women with a short allele may be either less attentive or less "expert" with regard to positive emotional stimuli, and ideas for future research are presented.     

Improved temporal clustering analysis method applied to whole-brain data in acupuncture fMRI study

Temporal clustering analysis (TCA) has been proposed as a method for detecting the brain responses of a functional magnetic resonance imaging (fMRI) time series when the time and location of activation are completely unknown. But TCA is not suitable for treating the time series of the whole brain due to the existence of many inactive pixels. In theory, active pixels are located only in gray matter (GM). In this study, SPM2 was used to segment functional images into GM, white matter and cerebrospinal fluid, and only the pixels in GM were considered. Thus, most of inactive pixels are deleted, so that the sensitivity of TCA is greatly improved in the analysis of the whole brain. The same set of acupuncture fMRI data was treated using both conventional TCA and modified TCA (MTCA) for comparing their analytical ability. The results clearly show a significant improvement in the sensitivity achieved by MTCA.     

基于模式识别的高水平运动员RS-fMRI数据分类研究

为弥补传统的广义线性模型(generalized linear model, GLM)方法的不足,并探索模式识别在运动脑科学当中的应用价值。使用支持向量机(support vector machine, SVM)模式识别算法,以低频振幅(fractional amplitude of low-frequency fluctuations, fALFF)、局部一致性(regional homogeneity, ReHo)和度中心度(degree centrality, DC)作为学习特征,对射击运动组和滑冰运动组(分类1)、射击运动组和对照组(分类2)以及速滑运动组和对照组(分类3)之间进行二分类,并计算每一个脑区在分类算法当中的权重。使用留一交叉验证法计算分类正确率,使用总的准确率、接受者操作特性曲线(receiver operating characteristic curve, ROC)、以及预测准确率来衡量机器分类算法的优劣性。结果表明：分类1中SVM算法的正确率较高且分类效果更稳定,总的准确率(total accuracy, tACC)可以维持在96.67%以上,曲线下面积(a...