基于度中心性的认知特征选择方法

针对大脑图谱认知特征选择的不确定性提出了基于度中心性的认知特征选择方法（DC-CFSM）。首先,基于大脑图谱构建认知实验任务中被试的脑功能网络（FBN）,并计算得到FBN每个兴趣点（ROI）的度中心性（DC）;其次,统计对比被试相同皮质兴趣点在执行认知任务时不同认知状态间的差异显著性并对其进行排序;最后,根据排序后的ROI计算人脑认知体系曲线下面积（HBCA-AUC）值,并评估几种认知特征选择方法的性能。在心算认知任务功能核磁共振成像（fMRI）数据上进行的实验中,DC-CFSM在人脑认知体系的任务正相关系统（TPS）、任务负相关系统（TNS）及任务支撑系统（TSS）上得到的HBCA-AUC值分别为0.669 2、0.304 0、0.468 5。与极限树、自适应提升、随机森林、极限梯度提升（XGB）等方法相比,DC-CFSM对TPS的识别率分别提高了22.17%、13.90%、24.32%和37.19%,对TNS的误识率分别减小了20.46%、29.70%、44.96%和33.39%。可见DC-CFSM在大脑图谱认知特征的选择上更能反映人脑认知体系的类别和功能。     

Anterior cingulate activity and level of cognitive conflict: Explicit comparisons.

The role of anterior cingulate cortex (ACC) in attention is a matter of debate. One hypothesis suggests that its role is to monitor response-level conflict, but explicit evidence is somewhat lacking. In this study, the activation of ACC was compared in (a) color and number standard Stroop tasks in which response preparation and interference shared modality (response-level conflict) and (b) color and number matching Stroop tasks in which response preparation and interference did not share modality (non-response-level conflict). In the congruent conditions, there was no effect of task type. In the interference conditions, anterior cingulate activity in the matching tasks was less than that in the standard tasks. These results support the hypothesis that ACC specifically mediates generalized modality-independent selection processes invoked by response competition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural basis of individual differences in impulsivity: Contributions of corticolimbic circuits for behavioral arousal and control.

The objective of the current study was to analyze the neural correlates of behavioral arousal and inhibitory control as they relate to individual differences in impulsivity via well-established functional MRI amygdala reactivity and prefrontal inhibitory control paradigms in healthy adult subjects. Impulsivity correlated positively with activity of the bilateral ventral amygdala, parahippocampal gyrus, dorsal anterior cingulate gyrus (BA 32), and bilateral caudate. Conversely, impulsivity correlated negatively with activity of the dorsal amygdala and ventral prefrontal cortex (BA 47). Together, these findings suggest that dispositional impulsivity is influenced by the functional interplay of corticolimbic behavioral arousal and control circuits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

脑激活任务区分度的分析及应用研究

大脑在执行不同类型任务时激活模式各不相同,变化很大,各个脑区的变化程度也不同。据此,提出任务区分度计算这一全新的方法。用相似性度量对任务态功能磁共振成像（functional Magnetic Resonance Imaging,fMRI）分析,衡量大脑在执行不同条件时各个脑区激活模式的区分程度,揭示大脑各个区域对任务的表征能力。实验对正常人和狂躁症患者记忆提取任务的fMRI数据进行分析,使用皮尔逊相关分析、余弦相似度分析和欧几里德距离计算3种常用的相似性度量方法,并计算各个脑区的任务区分度。结果表明区分度较高的脑区参与记忆、注意和视觉信息等功能,表明了该方法的准确性和科学性。狂躁症患者在负责记忆和注意等脑区的任务区分度较正常人低,表明患者脑功能受损。此外,研究还发现基于皮尔逊相关分析的区分度计算表现较好。通过与SVM方法的对比证明了该方法在区分不同任务的激活模式时的优越性。综上,基于相似性度量的脑激活任务区分度的方法能够适用于任务态fMRI分析及其相应的脑功能分析。     

基于时域与空域信息去除fMRI信号生理噪声的无监督方法

fMRI脑功能成像过程中的心跳和呼吸等生理噪声具有较强的自相关结构特性,因而会对后续数据分析造成干扰.结合生理噪声在时间域和空间域的综合特征,通过典型相关分析方法,可稳健地从非神经组织区域的残差数据中识别并去除生理噪声.并且所提方法不需要任何实验先验信息,实现了对fMRI生理噪声的无监督抑制.通过在真实fMRI数据上进行实验,阐明了该方法的有效性及可靠性.     

脑fMRI特征重建的分层快速聚类方法

在对大脑fMRI感兴趣区域的分析中,利用特征选择所得到的筛选属性进行特征重建问题上,提出了分层快速聚类的分析方法,同已有K-均值聚类方法相比,在聚类有效性得到提高的前提下,总体降低了聚类的时间代价,并为后续的回归分析处理提供了精确保证。     

基于卷积神经网络的fMRI数据分类方法*

功能性磁共振成像(fMRI)数据分类方法无法有效提取fMRI数据的局部特征,影响分类准确性.因此文中提出基于卷积神经网络的fMRI数据分类方法.首先设计卷积神经网络结构,并根据卷积神经网络的卷积核尺寸构建受限玻尔兹曼机模型.然后使用fMRI数据感兴趣区域体素构造数据,对受限玻尔兹曼机进行预训练,并将训练得到的权重矩阵进行相对变换,用于初始化卷积神经网络的卷积核参数.最后训练初始化好的整个模型,得到最终的分类模型.在Haxby和LPD数据集上的实验表明,文中方法可以有效提升fMRI数据的分类准确率     

fMRI脑图的感知状态分析 ——回归模型及其寻优的非同质检验

脑功能核磁共振图像fMRI的特点是定位准确,但信噪比低、数据量大。对fMRI数据的泛回归模型的超参数寻优问题作了分析,提出基于非同质检验的超参数确认方法,重点比较了它在线性和非线性的回归方式（包括岭回归,支持向量回归,Elman递归神经网络）下针对不同外界环境特征的回归能力差异,实验所采用原始数据均来自PBAIC2006,结果表明,该方法在对相关领域知识较少依赖的前提下,具有较好的稳定性和泛化能力;同时在所涉及到的回归方法当中,线性方法的实现简单、有效,在计算代价上低于其他方法,对多种外界特征具有较高的预测能力。     

Minding one’s emotions: Mindfulness training alters the neural expression of sadness.

[Correction Notice: An erratum for this article was reported in Vol 10(2) of Emotion (see record 2010-06281-006). The DOI printed in the article was incorrect. The correct DOI should be as follows: http://dx.doi.org/10.1037/a0017151.supp.] Recovery from emotional challenge and increased tolerance of negative affect are both hallmarks of mental health. Mindfulness training (MT) has been shown to facilitate these outcomes, yet little is known about its mechanisms of action. The present study employed functional MRI (fMRI) to compare neural reactivity to sadness provocation in participants completing 8 weeks of MT and waitlisted controls. Sadness resulted in widespread recruitment of regions associated with self-referential processes along the cortical midline. Despite equivalent self-reported sadness, MT participants demonstrated a distinct neural response, with greater right-lateralized recruitment, including visceral and somatosensory areas associated with body sensation. The greater somatic recruitment observed in the MT group during evoked sadness was associated with decreased depression scores. Restoring balance between affective and sensory neural networks—supporting conceptual and body based representations of emotion—could be one path through which mindfulness reduces vulnerability to dysphoric reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural responses to masked fear faces: Sex differences and trauma exposure in posttraumatic stress disorder.

Although women have a greater propensity than men to develop posttraumatic stress disorder (PTSD) following trauma, sex differences in neural activations to threat have received little investigation. This study tested the prediction that trauma would heighten activity in automatic fear-processing networks to a greater extent in women than in men. Functional magnetic resonance imaging (fMRI) data were recorded in 23 participants with PTSD (13 women, 10 men), 21 trauma-exposed controls (9 women, 12 men), and 42 non-trauma-exposed controls (22 women, 20 men) while they viewed masked facial expressions of fear. Exposure to trauma was associated with enhanced brainstem activity to fear in women, regardless of the presence of PTSD, but in men, it was associated only with the development of PTSD. Men with PTSD displayed greater hippocampal activity to fear than did women. Both men and women with PTSD showed enhanced amygdala activity to fear relative to controls. The authors conclude that greater brainstem activation to threat stimuli may contribute to the greater prevalence of PTSD in women, and greater hippocampal activation in men may subserve an enhanced capacity for contextualizing fear-related stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)