事件相关fMRI在广泛性焦虑症情绪刺激反应中的研究进展

对负性情绪刺激反应出现脑区活动异常是广泛性焦虑症(GAD)的重要表现。功能MRI(fMRI)在焦虑症情绪刺激的脑影像学研究中发挥着重要作用。对事件相关fMRI的特点及焦虑症fMRI常用的刺激范式和刺激材料予以简单介绍,并主要就事件相关fMRI在各年龄段GAD情绪刺激条件下脑功能改变及相关脑区之间联系的研究进行综述。     

基于脑血氧信号近似熵的麻醉深度监测方法研究

目的在全身麻醉状态下,研究麻醉与清醒阶段人脑前额脑血氧的近似熵值,得到一种新的麻醉深度监测指标。方法基于近红外光谱技术,采集了8位病人前额的左侧与右侧、近端与远端的脑血氧中的氧合血红蛋白(HbO_2)和还原血红蛋白(Hb)信号,应用近似熵算法对信号进行处理。结果 HbO_2与Hb信号的近似熵值在麻醉维持阶段大于清醒阶段,并且在这两个阶段之间存在显著性差异,通过ROC曲线分析表明近似熵指标对麻醉与清醒的区分能力较强。通过阈值分析表明近似熵指标能够设定统一的阈值。对左侧与右侧的组合信号进行比较分析,左侧与右侧间无显著性差异。结论本文提出的基于脑血氧信号的近似熵指标具有麻醉深度监测的应用价值。     

脑功能磁共振对梗死后抑郁症的研究

目的 采用功能性磁共振方法对梗死后抑郁症(PSD)患者观察正性、中性、负性情绪图片后的脑功能成像差异.资料与方法 对11例PSD患者和15名健康志愿者(NORM)进行正性、中性、负性情绪图片刺激下的脑功能磁共振成像研究.结果 PSD组及NORM组观察情绪图片时均主要激活额叶皮层-皮层下网状系统、基底节区(丘脑、苍白球、尾状核)和边缘系统(海马、海马旁回、杏仁核)、岛叶、颞叶,脑干及小脑.两组间有显著组间差异的激活脑区主要有海马旁回、海马、额中回、顶上小叶,扣带回(中性),右侧背侧丘脑、岛叶(正性),右侧杏仁核(负性).结论 PSD与边缘系统(海马、海马旁回、杏仁核)以及额中回、顶上小叶、扣带回、背侧丘脑、岛叶等有密切关系,上述脑区的损害可能参与了PSD的病理生理机制.     

追踪任务下脑波频率特征的变化特点研究

目的考察静态与不同难度追踪任务下脑波功率谱及优势频率涨落特征间的差异和变化特点。方法记录5名青中年男性静态(闭眼)和执行追踪任务过程中的EEG数据,应用脑波频率涨落分析技术分析相关的α段频率涨落特征及变化特点。结果静态与追踪任务态优势频率概率分布特征差异显著,追踪任务态优势频率概率分布曲线峰值向低频方向偏移,优势频率涨落熵显著增加,熵值的脑区分布特征显著改变,优势频率的不稳定性明显增强。不同难度追踪任务状态下优势频率序列均值及离散程度的变化与任务难度有关,优势频率涨落熵随追踪任务难度加大呈上升趋势。结论脑波α段频率涨落特征指标的变化反映了不同难度追踪任务下相关脑区活动的显著变化,表明该技术可应用于追踪任务负荷的研究。     

事件相关fMRI在广泛性焦虑症情绪刺激反应中的研究进展

对负性情绪刺激反应出现脑区活动异常是广泛性焦虑症（GAD）的重要表现。功能MRI（fMRI）在焦虑症情绪刺激的脑影像学研究中发挥着重要作用。对事件相关fMRI的特点及焦虑症fMRI常用的刺激范式和刺激材料予以简单介绍,并主要就事件相关fMRI在各年龄段GAD情绪刺激条件下脑功能改变及相关脑区之间联系的研究进行综述。     

正负性情绪图片编码加工功能磁共振成像研究

目的 探讨正负性情绪图片加工所涉及的相关神经机制. 资料与方法 对20名健康自愿者(男女各10名,年龄20～25岁,视觉呈现彩色负性、正性、中性情景图片)行功能磁共振成像扫描并进行后处理. 结果 与中性图片加工相比,正负情绪激活杏仁核、前额叶不同亚区、扣带回、颞中回、颞上回等共同脑区.负性图片显著激活双侧杏仁核、右侧前额叶眶回、左侧海马、丘脑和梭状回等脑区;正性图片激活右侧杏仁核、左侧前额叶背侧和右侧海马等脑区. 结论 正负性情绪加工涉及共同的和相对特异的神经机制.前额叶和杏仁核等是情绪加工中的重要结构,前额叶参与情绪加工符合情绪效价假设.     

脊髓损伤患者运动想象期间的近红外脑功能成像研究

目的 采用近红外脑功能成像(fNIRS)技术,对比脊髓损伤(SCI)患者与健康受试者"屈伸右膝"运动想象(MI)和运动执行(ME)任务态下脑区激活模式,为MI疗法治疗SCI患者运动功能障碍提供神经影像学理论依据.方法 前瞻性研究2021年6月—2021年8月中南大学湘雅二医院康复科收治的21例SCI患者与同期面向社会公...     

利用fMRI研究正常人执行Stroop任务的脑功能网络

目的:利用功能磁共振成像(fMRI)探讨正常人执行汉字Stroop任务时任务相关的激活与去激活脑功能网络。方法:14例正常志愿者接受了Stroop任务的组块式fMRI,扫描序列为平面回波血氧水平依赖(BOLD)序列,利用统计参数图(SPM99)软件进行图像分析。所有检查完毕后,对受试者进行Stroop的行为学测试,记录反应时间及错误数。结果:正常对照组认字试验的反应时间与颜色命名试验之间差异有显著性意义(t=-8.188,P=0.000)。对照状态下,正常人出现后扣带回皮层、中线前额叶皮层、背侧前扣带回的去激活。正常人执行颜色命名任务较认字任务时出现更多脑区的激活,且其激活强度较第1个任务的脑区激活强度增加。执行颜色命名任务时动用了双侧额中回、左侧额上回、左侧额下回及双侧顶叶。结论:本研究进一步证实静息状态下存在大量的神经元活动,其与任务相关的脑功能网络共同维持正常的认知活动。     

正常人工作记忆任务和静息状态下前额叶皮层内侧面的功能连接分析

目的 分析在工作记忆任务和静息两种状态下与前额叶皮层内侧面(MPFC)正、负相关脑区的分布,比较两种状态下MPFC功能连接的差异.资料与方法 采用GE 1.5 T MR扫描仪对25名正常自愿者行静息态及2-back工作记忆任务的功能磁共振成像(fMRI)实验,2-back实验采用组块设计,0-back作为对照,6个对照组块与5个任务组块交替进行.静息态全脑采集128个时相.采用SPM、AFNI对数据进行预处理.选择MPFC作为种子点与全脑其他像素进行Pearson相关分析,建立相关图.组内分析时采用随机效应模型单样本t检验,检测与MPFC明显正相关或负相关的脑区.组间分析采用配对样本t检验.检测MPFC功能连接图在2-back任务和静息状态下的差异.结果 两种状态下与MPFC正相关的脑区基本一致,属于"任务负激活网络".2-back任务状态下与MPFC负相关的脑区与"任务正激活网络"一致.静息状态下与MPFC负相关的脑区主要分布在双侧岛叶、双侧顶下小叶,且这些区域的负相关性明显高于任务状态.任务状态下负相关性高于静息状态的主要脑区包括双侧运动前区外侧(LPMA)、双侧顶叶后部(PPC)、左侧丘脑及右侧小脑半球.结论 静息及2-back任务状态下MPFC的功能连接情况不同,对于正常人在静息及任务状态下的功能连接对比研究为临床精神疾病患者的研究奠定了基础.     

脑网络功能连接预测抑郁症重复经颅磁刺激疗效的研究进展

抑郁症是一种情感障碍性疾病。重复经颅磁刺激(rTMS)是治疗抑郁症的一种非侵入性神经刺激技术。静息态功能磁共振成像(rs-fMRI)主要是研究大脑在静息状态时的自发活动;功能连接在分析抑郁症rTMS时较为常用,反映了静息状态下不同脑区血氧信号的即时联系,表明不同脑区间连接上的功能差异。本研究对近年脑网络功能连接预测rTMS治疗抑郁症疗效的相关文献进行综述,有望为抑郁症rTMS个性化治疗提供思路。     

前额叶皮层在数字工作记忆维持中的作用:事件相关fMRI研究

目的采用事件相关功能磁共振成像(ER-fMRI)探讨前额叶皮层在工作记忆维持期的作用。方法20名正常受试者接受sternberg项目认知任务的功能磁共振成像。采用相对低负载、高负载任务。组分析方法评价维持期相对低、高负载时平均脑区激活情况;组间比较探讨高负载任务出现相关激活增加的脑区。结果维持期与双侧前额叶背外侧皮层(DLPFC)、双侧前额叶腹外侧皮层(VLPFC)、顶叶、辅助运动区(SMA)和运动前区(PMA)、视觉相关皮层激活相关,VLPFC等脑区在高负载任务中激活增加。结论工作记忆维持和操纵之间可能存在功能上的、而非神经解剖的区分。     

Functional MR Imaging of Working Memory in the Human Brain

Objective

In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed.

Materials and Methods

In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p < .001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks.

Results

The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere.

Conclusion

The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.     

Cortical activation during gait adaptability in people with Parkinson’s disease

BackgroundPeople with Parkinson’s disease (PD) have difficulties adapting their gait. While underlying neural mechanisms involving the prefrontal cortex (PFC) have been studied across various complex walking tasks, less is known about the premotor cortex (PMC) and supplementary motor area (SMA), key cortical regions for motor planning. This study compared frontal cortical regions activation patterns using functional near-infrared spectroscopy (fNIRS), between people with PD and healthy controls (HC) during gait adaptability tasks.MethodsForty-nine people with PD (mean (SD) age: 69.5 (7.9) years) and 21 HC (69.0 (5.9) years) completed a simple walk and three randomly presented gait adaptability tasks: (i) stepping on targets, (ii) avoiding obstacles and (iii) negotiating both targets and obstacles. Cortical activity in the dorsolateral PFC (DLPFC), SMA and PMC were recorded using fNIRS. Step length, velocity and accuracy and cortical activity were contrasted between the groups and walking conditions.ResultsCompared with the HC, the PD group exhibited greater PMC activation and walked significantly slower and took shorter steps in all conditions. A statistically significant group by condition interaction indicated an increase in DLPFC cortical activation in the HC participants when undertaking the obstacle avoidance task compared with the simple walk but no increase in cortical activation in the PD group when undergoing this more challenging gait task.ConclusionsOur findings suggest people with PD have little or no DLPFC, SMA and PMC capacity beyond what they need for simple walking and in consequence need to slow their gait velocity to meet the demands of target stepping and obstacle avoidance tasks. Such behavioral and neural patterns appear consistent with concepts of compensatory over-activation and capacity limitation.     

用近红外功能成像技术研究语义和知觉编码过程中左前额叶的活动

目的用近红外光学功能成像技术研究语义与知觉编码过程中的左前额叶活动.方法实时记录22名青年被试者(男女各半)在语义和知觉加工过程中760 nm和850 nm两个波长近红外连续光透过额骨和左前额皮层后的漫射光强变化,并以此表征该皮层区血容(CBV)和血氧的变化.语义加工要求被试者用两个非相关的汉字词对组成一个有意义的句子;知觉加工则要求被试者判断两个词是否具有相同的结构组合以及两个词对中左右结构的差别. 结果结果显示,与知觉加工相比,语义加工时左下前额叶活动增多.该区域大致对应布德曼45、47区的一部分. 结论成功地利用近红外功能成像技术观测了语义与知觉编码过程中的左前额叶活动,获得了与fMRI和断层成象技术(PET)研究相近的结果,进一步证实了左前额叶在语义加工中的作用.     

近红外光学成像技术检测视觉搜索任务期间大脑前额叶氧合血红蛋白水平变化

目的 研究视觉搜索对大脑前额叶氧合血红蛋白水平变化的影响.方法 25名右利手健康大学生被试者在一列非靶字母中搜索靶字母,依据非靶字母数目(2个或6个),将任务分为2个水平(任务1或2).实验期间同时记录被试者行为反应和前额叶脑区氧合血红蛋白水平变化.结果 1)与任务1相比,任务2期间被试者反应时延长、正确率下降,前额叶脑区氧合血红蛋白水平明显上升;2)任务2期间被试者前额叶脑区激活水平与反应时呈负相关.结论 前额叶区域氧合血红蛋白反应与视觉搜索行为结果相一致,较高的氧合血红蛋白水平有可能缩短行为反应时间.     

Functional asymmetries in early learning during right,left, and bimanual performance in right‐handed subjects

Purpose:

To elucidate differences in activity and connectivity during early learning due to the performing hand.

Materials and Methods:

Twenty right‐handed subjects were recruited. The neural correlates of explicit visuospatial learning executed with the right, the left hand, and bimanually were investigated using functional magnetic resonance imaging. Connectivity analyses were carried out using the psychophysiological interactions model, considering right and left anterior putamen as index regions.

Results:

A common neural network was found for the three tasks during learning. Main activity increases were located in posterior cingulate cortex, supplementary motor area, parietal cortex, anterior putamen, and cerebellum (IV–V), whereas activity decrements were observed in prefrontal regions. However, the left hand task showed a greater recruitment of left hippocampal areas when compared with the other tasks. In addition, enhanced connectivity between the right anterior putamen and motor cortical and cerebellar regions was found for the left hand when compared with the right hand task.

Conclusion:

An additional recruitment of brain regions and increased striato‐cortical and striato‐cerebellar functional connections is needed when early learning is performed with the nondominant hand. In addition, access to brain resources during learning may be directed by the dominant hand in the bimanual task. J. Magn. Reson. Imaging 2013;37:619–631. © 2012 Wiley Periodicals, Inc.     

Minimum detectable change in motor and prefrontal cortex activity over repeated sessions using 3T functional MRI and a block design

Purpose

To determine the minimum detectable change (MDC) in functional magnetic resonance imaging (fMRI) measurements of brain activity over repeated sessions with 95% confidence using a block design of tasks.

Materials and Methods

Fourteen individuals participated in three sessions on different days during which four scans each of a motor task and working memory task were performed. Using a region‐of‐interest analysis of variance, we calculated the MDC in the volume of activated primary sensorimotor cortex (for motor) and dorsolateral prefrontal cortex (for working memory), as well as the percent increase in MR signal and the center and location of maxima of the activated voxels.

Results

The MDC of activated volume was 5.0–8.8 cm³, and the MDC of percent increase in signal from baseline during tasks was 0.3%–0.6%. The MDC of the center of mass of activity was 3–4 mm, compared to 6–10 mm for the location of maxima.

Conclusion

fMRI measurements that quantify the strength of activity in response to tasks and centers of mass offer sensitive measurements of change over repeated imaging sessions. fMRI can be used for serial investigations of individual participants using simple motor and cognitive tasks using a simple block design. J. Magn. Reson. Imaging 2008;28:1055–1060. © 2008 Wiley‐Liss, Inc.     

编码非相关词对是否具有半球对称性?一项近红外光学成像的研究

目的本研究采用近红外光学成像技术（fNIRS）,探讨双侧前额叶在非相关词对的语义编码过程中的作用。方法48名被试者分别在深、浅加工2种实验条件下对非相关词对进行编码,光学成像器即时记录在前额叶皮层,波长为760nm和850nm的漫射光强变化,以此推测相应脑组织的血容量变化。结果与浅加工相比,在深加工条件下,双侧前额叶中与背外侧前额叶相对应区域的血容量变化都较为明显,尤其是左侧前额叶。本研究结果并不完全支持HERA模型,但与其它相关的脑成像研究结果相似。结论材料的特异性是影响记忆编码中半球一侧化的重要因素,当需要对刺激间的联系进行加工时,右侧前额叶也会参与记忆的编码过程。本研究还提示fNIRS技术可用于记忆等脑高级认知功能的研究。     

对人脑执行功能激活区域间关系的因果分析研究

目的 探讨任务状态下注意网络中执行功能的脑激活状态,以及激活区域间的因果关系.方法 利用GE公司Signa1.5T磁共振成像系统,采用注意网络实验范式,对15例（男性8例,女7例）健康受试者在任务态下进行功能磁共振扫描,根据激活位置选取感兴趣区,利用系数Granger因果分析方法计算每两个感兴趣区之间的Granger因果关系,生成Granger因果数据,利用SPSS 18.0软件对所得数据进行统计分析.结果 被试的行为学数据符合实验需要,激活区域为前扣带回、背外侧前额叶皮质、右顶上小叶、右顶下小叶.Granger因果分析结果显示前扣带回与背外侧前额叶皮质构成因果关系,背外侧前额叶皮质、右顶上小叶、右顶下小叶构成因果关系并形成单向回路.结论 在注意网络实验范式下,执行功能是由前扣带回、背外侧前额叶皮质、右顶上小叶、右顶下小叶共同参与完成的,其中前扣带回主要功能为发现冲突,而背外侧前额叶及其所形成的单向环路主要功能为解决冲突.