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。     

脑肿瘤患者手术前后脑结构网络拓扑属性研究

主要研究脑肿瘤的存在及手术对患者全脑及半脑结构网络拓扑属性的影响。结合弥散张量成像技术(DTI)和图论方法,对10例健康志愿者以及10例脑肿瘤患者进行术前术后全脑及半脑结构网络构建,获得两组受试者脑结构网络拓扑属性参数,以及反映脑认知功能的各项网络指标,并对其进行统计对比分析。结果显示,部分局部参数(包括K_i、L_i、E_nodal、C_i和E_ilocal)在手术前后具有明显差异,且术前组均优于术后组;全脑及半脑各全局网络参数显示,各项参数术前组均优于术后组;同时半脑结构网络分析显示,位于不同脑半球的脑肿瘤对患者脑结构网络所造成的损伤均无统计学差异(P>0.05)。肿瘤的存在以及手术均使得脑肿瘤患者脑结构网络发生改变,大脑的半脑优势化趋势明显降低;手术后结构网络拓扑特性的改变以及小世界属性的增强,验证大脑本身存在的代偿机制以及功能重组现象。     

中风后大脑网络的改变

脑中风是一种常见的多发病,对于中风后的机理,到目前为止还没有完全的定论。本研究的目的是根据复杂网络的拓扑性质来研究中风患者全局脑功能网络和正常人全局脑功能网络的区别。实验中采用3 T磁共振设备采集了7个患者和6个健康人在对指运动下的功能磁共振的数据。利用DPARSF软件对数据进行处理,提取AAL模板对应90个脑区的时间序列。把每个脑区对应为一个节点,然后计算每两个时间序列之间的皮尔逊相关系数,以此构建邻接矩阵并建立网络。计算每个被试网络的全局效率、聚类系数、节点度以及节点介数,然后把患者组和健康组的参数结果平均。实验结果表明中风患者大脑的全局效率(患者组:0.496 7;健康组:0.586 9)、聚类系数(患者组:0.418 9;健康组:0.476 8)以及节点度都低于健康组;患者组节点介数存在为0的节点,而健康组没有介数为0的节点。这可能意味着中风之后患者的脑网络趋于泛化,效率降低,并存在网络断点。     

基于DTI的胶质瘤患者手术前后脑网络特性分析

目的利用弥散张量成像(diffusion tensor imaging,DTI)技术构建胶质瘤患者手术前后全脑结构网络和半脑结构网络,基于图论知识对脑网络参数进行定量研究及对比分析,探究胶质瘤及肿瘤切除手术对患者脑网络拓扑特性的影响。方法构建健康对照组、胶质瘤患者组手术前后全脑和半脑结构网络,定量分析两组大脑结构网络拓扑特性及网络参数,比较分析手术对患者全脑及半脑网络特性的影响。结果从全脑角度看,患者术后各全局网络参数较正常人均有所降低,但是小世界特性却有所增强,患者各全局参数在术前术后均无显著差异,患者术后的全脑局部参数明显低于术前;在半脑结构网络中,手术前后半脑全局参数无明显差异,而术后半脑全局参数明显低于术前。结论手术使得脑结构网络的局部脑区发生损伤,但并未对患者全脑及半脑全局参数造成显著影响,研究证实了人类大脑的代偿机制以及功能重组。该研究方法可对胶质瘤患者术后的疾病发展状况以及手术治疗效果评价提供帮助。     

脑功能连接特征判别青少年注意缺陷多动障碍的探索

目的:基于静息态脑功能连接特征建立注意缺陷多动障碍(ADHD)的智能诊断模型。方法:收集符合DSM-IV标准的60例8～16岁的ADHD患者和92例正常对照的静息态脑功能核磁共振成像数据,比较两组脑区间的功能连接,运用机器学习,探讨与机器学习理论的双重信息特征筛选方法得到的30个最优特征集合对ADHD诊断的预测性能。结果:ADHD在默认网络和感觉运动网络之间功能连接增强,默认网络内部,以及默认网络和小脑网络间的功能连接减弱。ADHD距离较远脑区间功能连接减弱,而距离较近的脑区间功能增强。模型的灵敏度和特异度分别可达80.3%和90.0%。结论:结合新的机器学习模型,运用ADHD脑功能连接特征的诊断方法可以获得较高的准确率。     

基于弥散张量成像的脑结构网络参数研究

目的 利用复杂网络参数评估大脑特征,是探明大脑工作机制的新思路。方法 本研究基于弥散张量纤维束追踪和小世界网络理论构建脑结构网络。首先利用自动解剖标定（automated anatomical labeling,AAL）模板对大脑分区,并计算脑区间的纤维连接情况,对正常人的大脑结构进行网络建模。然后分析脑结构网络中节点度、簇系数和节点介数等网络参数,并通过引入小世界网络的介数和损伤性定义人脑结构网络的核心节点位置和特征。结果 脑结构网络具有小世界属性,且网络中存在少量的核心节点,具有较高的节点度和簇系数值。结论 利用弥散张量成像能够客观构建大脑结构网络,而核心节点的存在为揭示脑疾病的病理生理机制提供新的思路。     

认知行为治疗对成人注意缺陷多动障碍静息态局部脑功能影响

目的:探讨认知行为治疗(CBT)对成人注意缺陷多动障碍(ADHD)患者静息态局部脑功能的影响。方法:被试包括10例18~65岁、符合精神障碍诊断与统计手册第4版(DSM-Ⅵ)ADHD诊断标准的患者及12例年龄、性别匹配的正常对照。对成人ADHD患者在CBT治疗前分别使用ADHD评定量表(ADHD-RS)及执行功能行为评定量表成人版自评问卷(BRIEF)进行症状、执行功能的评估,并进行静息态功能磁共振成像(rfMRI)扫描,此后进行12次CBT治疗,治疗完成后进行第2次症状、执行功能评估及MRI扫描,以观察ADHD症状、执行功能及静息态局部一致性(ReHo)的变化;对正常对照进行一次ADHD症状、执行功能评估及MRI扫描。结果:CBT治疗后ADHD患者的ADHD症状量表总分[(43±7)vs.(31±7),P0.01]、注意缺陷分及多动/冲动分降低,BRIEF中的监控[(15±2)vs.(11±2),P0.01]及组织因子[(19±5)vs.(14±4),P0.01]的分数降低。在脑功能层面,治疗前,成人ADHD患者默认网络内脑区(左侧海马旁回)及双侧前扣带回ReHo值低于正常对照,治疗后,成人ADHD患者默认网络内脑区(右侧海马旁回)及额-顶网络内脑区(右侧中央前、后回及左侧中央后回)的ReHo值增高,但右侧额上回的ReHo值仍低于正常对照(P0.05,团块体积3051mm3,校正后P0.01)。结论:CBT治疗可以改善成人ADHD患者的核心症状及认知功能,对默认网络内(海马旁回)及额-顶网络内(双侧中央前后回)脑区功能可能有影响,此脑功能的改变可能是ADHD症状和执行功能改善的神经基础。     

阿尔茨海默病患者默认网络社团结构的分析

研究表明,默认网络(DMN)的功能失调与阿尔茨海默病有关。为进一步发现阿尔茨海默病患者大脑默认网络存在的异常连接结构,使用最小生成树方法构建无偏的脑网络,采用树层次聚类方法分析早期轻度认知障碍组(EMCI)、晚期轻度认知障碍组(LMCI)、阿尔茨海默病患者(AD)和健康对照者(NC)DMN社团结构的变化,并且对4种被试大脑网络中回直肌-眶部额上回、楔前叶-后扣带回的连接以及颞上回中心性进行差异分析。结果显示:DMN在NC和EMCI中分成5个社团,在LMCI中分成7个社团,但是在AD分成9个社团;LMCI和AD在回直肌-眶部额上回的连接存在显著差异(P=0.048),LMCI和EMCI在楔前叶-后扣带回的连接存在显著差异(P=0.042),LMCI和NC在楔前叶-后扣带回的连接存在显著差异(P=0.016);颞上回介数中心性在AD组与LMCI组(P=0.028)、LMCI组与NC组(P=0.001)、EMCI组与NC组(P=0.048)都存在显著差异。阿尔茨海默病患者随着病情的进展,DMN的结构逐渐分散,脑区之间的连接以及中心性发生变化,这些脑区主要包括海马、海马旁回、楔前叶、后扣带回、眶部额上回、眶部额中回、回直肌和颞上回。     

基于静息态fMRI和DTI的大脑性别差异性研究

本研究从功能和结构两个方面来研究大脑存在的性别差异。利用ICA方法从大脑静息态fMRI数据中分离出大脑默认网络和感觉运动网络,通过双样本t检验来分析男女两性在脑皮层功能上所表现出来的异同;通过构建大脑白质纤维束结构网络,利用网络特征参数来分析男女脑部纤维结构上所存在的差异;通过二者联合技术来探讨两性大脑功能差异和结构差异的关系。结果发现两性大脑功能差异和结构差异在某些脑区有一定的一致性。男女两性大脑生理结构和功能有一定的关联性,两性大脑在功能上的差别可认为与两性在负责相关功能的脑区所具有的差异相关。     

作曲家大脑的静息态脑功能网络研究

音乐家大脑是认识大脑可塑性机制的天然模型,也是脑影像科学关注的重点研究对象之一。但是,目前针对音乐家的研究,包括对音乐创作方面的脑机制研究,仍以钢琴演奏家为主要研究对象。鉴于创作与表演是两个不同阶段且存在巨大差异,仅以钢琴演奏家作为研究对象对音乐家脑机制的研究是不完整的。专业作曲家是一类特殊的音乐家,他们经历过长期的音乐训练,能够在创造性思维的引领下,结合情感等要素来进行音乐素材的组织。用功能磁共振(fMRI)采集29名作曲家在作曲任务前后的大脑静息态影像,利用独立成分分析方法分离出其脑功能网络中常见的13个成分。采用配对t检验,对比分析作曲前后这些成分的变化。结果发现,在完成作曲任务后,以下脑功能网络连接显著减弱,包括听觉网络(AN)与右侧额顶网络(RFPN)、感觉运动网络(SMN)与突显网络(SN);同时也发现在完成作曲任务后,以下脑功能网络连接显著增强,包括自我参照网络(SRN)与视觉I区网络(VN1)、自我参照网络(SRN)与视觉II区网络(VN2)、默认模式网络(DMN)与视觉I区网络(VN1)。这些结果证明,感觉、认知加工等与视觉区域的协调整合在作曲过程中的重要性,对推动音乐家大脑可塑性的认识和音乐创作的脑机制研究均十分有意义。     

帕金森病人脑电溯源与脑功能网络特性研究

帕金森病是老年人群中常发的神经退行性疾病,目前仍然缺乏公认的特异生化诊断指标。为了探索帕金森患者和健康受试的脑电差异,对26 名帕金森患者和26 名健康受试者进行闭眼静息态EEG的采集,利用MMSE和MoCA量表对受试者的认知功能进行主观评定,利用UPDRS和H&Y分级对受试者的运动功能进行评估。首先采用标准化低分辨率脑电磁层析成像对两组受试者脑电信号进行了溯源分析,而后采用滞后相位同步方法对脑功能网络进行差异性分析,进而对比分析两组受试者脑功能网络的拓扑特性。溯源分析结果表明,与健康对照组相比,PD组存在差异的脑区是枕叶和顶叶,α2频段楔前叶(BA7)电流密度显著降低;β1频段额叶与枕叶之间脑功能连接降低,患者脑功能网络的平均聚类系数C、全局效率E_g和节点度D比健康对照组显著降低(P<0.01)(患者: C=0.54±0.14,Eg=0.71±0.09,D=26.88±9.88;健康对照组: C=0.75±0.13,Eg=0.83±0.09,D=42.21±11.19),患者组平均特征路径长度L比健康对照组显著升高(患者: L=1.61±0.2;健康对照组: L=1.34±0.19,P< 0.01)。本研究α2频段楔前叶电流密度显著降低以及β1频段脑功能连接效率降低对帕金森病的诊断具有指导意义。     

Functional and Structural Alterations in Temporal Lobe Tumor Patients: Evidence of Functional Compensation in the Human Brain

Patients with temporal lobe tumor are frequently accompanied by cognitive impairments. This study aims to combine diffusion tensor imaging(DTI) with resting-state functional magnetic resonance image(fMRI) to explore the underlying cognitive alternation and functional reorganization in patients with temporal lobe tumor.Twenty patients with right temporal lobe tumor and seventeen healthy volunteers were recruited in this study. Independent component analysis(ICA) was utilized to divide the whole brain into six sub functional networks, and DTI combined with graph-based topological analysis was used to calculate the structural properties of whole-brain and sub functional networks. Besides, the rich hubs in both patients and healthy controls(HCs)were identified and a further analysis of their internal functional and structural connectivity was also conducted. The E_(global) in self-referential network(SRN) of patients is higher than HCs, while decreased E_(global) of dorsal attention network(DAN) and default mode network(DMN) were found in patients. For the patients, brain regions with increased nodal efficiency(E_(nodal)) were located in the frontal lobe(corresponding to SRN). Six identical hubs were found in two groups. Compared patients with HCs, significant between-group differences in both functional and structural connectivity were observed between right insula(INS.R) and right lenticular nucleus, putamen(PUT.R). The findings provide evidence that impaired cognition are closely related to functional and structural abnormalities and the compensatory roles of frontal lobe were also identified in patients.The proposed combination of DTI and f MRI promises a widespread utilization in clinical research on the mechanisms of neurological diseases.     

The neural basis of the psychomotor vigilance task

STUDY OBJECTIVE: To identify brain regions underlying the fastest and slowest reaction times on the Psychomotor Vigilance task (PVT) under well-rested conditions, as well as brain regions related to particularly poor performance after sleep deprivation. DESIGN: Subjects took the PVT twice while undergoing functional magnetic resonance imaging: once 12 hours after waking from a normal night of sleep and once after 36 hours of total sleep deprivation (TSD). Session order was counterbalanced. SETTING: UCSD J. Christian Gillin Laboratory for Sleep and Chronobiology (the sleep core of the General Clinical Research Center) and UCSD Magnetic Resonance Institute. PATIENTS OR PARTICIPANTS: Twenty right-handed healthy adults (8 women; age = 27.4 +/- 6.7 years; education = 15.6 +/- 1.5 years). MEASUREMENTS AND RESULTS: After a normal night of sleep, optimal performance was related to greater cerebral responses within a cortical sustained attention network and the cortical and subcortical motor systems. Slow reaction times, particularly after TSD, were associated with greater activity in the "default mode network" consisting of frontal and posterior midline regions. CONCLUSIONS: Optimal performance on the PVT appears to rely on activation both within the sustained attention system and within the motor system. Poor performance following TSD may result from a disengagement from the task and related inattention, and brain regions responsible for this localize within midline structures shown to be involved in the brain's "default mode." Finally, particularly poor performance after TSD may elicit a subsequent attentional recovery that manifests as greater activation within the same regions normally responsible for fast reaction times.     

基于脑网络的脑疲劳对不同工作记忆负荷的影响

工作记忆是认知行为的基础,脑疲劳会导致记忆力衰退、反应迟钝等认知表现下降的现象.利用N-back实验范式设计脑疲劳实验,采集15名被试正常态和疲劳态下4种工作记忆负荷的脑电数据,使用互信息算法构建功能性脑网络,计算并分析节点度、节点中间中心度、节点聚类系数、节点特征路径长度4个网络特征参数,对行为学数据(反应时间、正确...     

Associations between insomnia symptoms and functional connectivity in the UK Biobank cohort (n = 29,423)

An increasing number of studies harness resting-state fMRI functional connectivity analysis to investigate the neurobiological mechanisms of insomnia. The results to date are inconsistent and the detection of minor and widely distributed alterations in functional connectivity requires large sample sizes. The present study investigated associations between insomnia symptoms and resting-state functional connectivity at the whole-brain level in the largest sample to date. This cross-sectional analysis used resting-state imaging data from the UK Biobank, a large scale, population-based biomedical database. The analysis included 29,423 participants (age: 63.1 ± 7.5 years, 54.3% female), comprising 9210 with frequent insomnia symptoms and 20,213 controls without. Linear models were adjusted for relevant clinical, imaging, and socio-demographic variables. The Akaike information criterion was used for model selection. Multiple comparisons were corrected using the false discovery rate with a significance level of q < 0.05. Frequent insomnia symptoms were associated with increased connectivity within the default mode network and frontoparietal network, increased negative connectivity between the default mode network and the frontoparietal network, and decreased connectivity between the salience network and a node of the default mode network. Furthermore, frequent insomnia symptoms were associated with altered functional connectivity between nodes comprising sensory areas and the cerebellum. These functional alterations of brain networks may underlie dysfunctional affective and cognitive processing in insomnia and contribute to subjectively and objectively impaired sleep. However, it must be noted that the item that was used to assess frequent insomnia symptoms in this study did not assess all the characteristics of clinically diagnosed insomnia.     

经颅直流电刺激干预工作记忆的脑功能网络研究

工作记忆是高级认知功能的重要基础,为探索经颅直流电刺激(tDCS)对工作记忆的影响及具体机制,招募18位被试参加实验,采集被试在伪/阳极/阴极tDCS刺激后三图、四图以及五图记忆负载任务中的行为数据(准确率、反应时长)与脑电信号.首先根据行为数据对工作记忆能力进行评估,再利用不同通道之间脑电信号的相关性,构建各状态下的...     

rTMS联合运动训练对静息态脑网络影响的研究

重复经颅磁刺激(rTMS)联合运动训练可以提高肢体运动能力,在脑卒中后的运动康复中有重要的应用价值。探讨rTMS联合运动训练对静息态脑网络的影响。招募10名健康受试者,使用1 Hz rTMS刺激优势半球,结束后非利手立即执行运动训练,以提高非利手的运动能力,rTMS联合运动训练共持续14天。采集rTMS联合运动训练前后闭目静息态的脑电(EEG)信号,使用相位延迟指数(PLI)进行功能连接性分析,并以PLI值为边的权重计算依据来建立有权无向脑网络,计算网络节点的最短路径长度和节点效率,使用非参数符号秩和检验进行统计学分析。结果发现,rTMS联合运动训练使EEG低频段(theta和alpha)脑功能区间的连接显著增加、高频段(beta、gamma₁和gamma₂)显著降低,对脑功能区内的连接影响较小。特别地,采取rTMS联合运动训练,使alpha频段非优势侧中央区与优势侧额叶区(训练前0.141 4±0.102 5,训练后0.217 2±0.134 7,P<0.05)、非优势侧额叶区(训练前0.141 0±0.109 9,训练后0.205 9±0.136 1,P <0.05)的功能连接性显著增加。网络特征结果显示,节点效率在低频段增加、高频段降低,而节点最短路径长度表现出相反的结果,其中gamma₂频段在双侧中央区的节点效率(左中央区,实验前0.060 0±0.000 3,实验后0.042 9±0.001 3,P <0.05;右中央区,实验前0.060 7±0.002 3,实验后0.041 9±0.002 4,P <0.05)和最短路径长度(左中央区,实验前18.539 0±0.457 1,实验后28.585 8±1.001 4,P<0.05;右中央区,实验前18.650 8±0.438 6,实验后28.853 0±1.652 6,P <0.05)发生显著性的改变。通过该项研究,加深对rTMS联合运动训练促进运动能力神经机制的理解,为未来探究其对脑卒中、脑损伤患者脑活动的影响提供帮助。     

Reorganization of Motor Representations in Patients with Brain Lesions: A Navigated Transcranial Magnetic Stimulation Study

This is an explorative study applying presurgical navigated transcranial magnetic stimulation (nTMS) to investigate the spatial distributions of motor sites to reveal tumor-induced brain plasticity in patients with brain tumors. We analyzed nTMS-based motor maps derived from presurgical mapping of 100 patients with motor eloquently located brain tumors (tumors in the frontal lobe, the precentral gyrus [PrG], the postcentral gyrus [PoG], the remaining parietal lobe, or the temporal lobe). Based on these motor maps, we systematically investigated changes in motor evoked potential (MEP) counts among 4 gyri (PrG, PoG, medial frontal gyrus, and superior frontal gyrus) between subgroups of patients according to the tumor location in order to depict the tumor’s influence on reorganization. When comparing patients with different tumor locations, high MEP counts were elicited less frequently by stimulating the PrG in patients with tumors directly affecting the PrG (p?<?0.05). Still, in more than 50% of these patients, the MEP counts elicited by stimulating the PrG were higher than average, indicating robust motor representations within the primary motor cortex. In contrast, patients with PoG and parietal tumors primarily showed high MEP counts when stimulating the PoG (p?<?0.10). The functional reorganization is not likely to induce a shift of motor function from the PrG to adjacent regions but rather leads to a reorganization within anatomical constraints, such as of the PoG. Thus, presurgical nTMS-based motor mapping sensitively depicted the tumor-induced plasticity of the motor cortex.     

Altered functional brain networks in Prader–Willi syndrome

Prader–Willi syndrome (PWS) is a genetic imprinting disorder characterized mainly by hyperphagia and early childhood obesity. Previous functional neuroimaging studies used visual stimuli to examine abnormal activities in the eating‐related neural circuitry of patients with PWS. It was found that patients with PWS exhibited both excessive hunger and hyperphagia consistently, even in situations without any food stimulation. In the present study, we employed resting‐state functional MRI techniques to investigate abnormal brain networks related to eating disorders in children with PWS. First, we applied amplitude of low‐frequency fluctuation analysis to define the regions of interest that showed significant alterations in resting‐state brain activity levels in patients compared with their sibling control group. We then applied a functional connectivity (FC) analysis to these regions of interest in order to characterize interactions among the brain regions. Our results demonstrated that patients with PWS showed decreased FC strength in the medial prefrontal cortex (MPFC)/inferior parietal lobe (IPL), MPFC/precuneus, IPL/precuneus and IPL/hippocampus in the default mode network; decreased FC strength in the pre‐/postcentral gyri and dorsolateral prefrontal cortex (DLPFC)/orbitofrontal cortex (OFC) in the motor sensory network and prefrontal cortex network, respectively; and increased FC strength in the anterior cingulate cortex/insula, ventrolateral prefrontal cortex (VLPFC)/OFC and DLPFC/VLPFC in the core network and prefrontal cortex network, respectively. These findings indicate that there are FC alterations among the brain regions implicated in eating as well as rewarding, even during the resting state, which may provide further evidence supporting the use of PWS as a model to study obesity and to provide information on potential neural targets for the medical treatment of overeating. Copyright © 2013 John Wiley & Sons, Ltd.