磁刺激神门穴脑电信号诱发电位分析及源定位

背景：磁刺激技术是一种新型生物刺激技术,鉴于其使用方便且无痛无创,所以可以采用磁刺激技术刺激穴位替代针刺或电刺穴位。脑电信号可以反映大脑皮质神经的兴奋状态,所以磁刺激与神经相关的神门穴并测量与分析其脑电信号可以研究磁刺激穴位的作用与效果。 目的：以不同频率磁刺激刺激肢体神门穴,观察在4种不同状态下脑电信号的诱发电位及其偶极子源定位。 方法：选择健康右利手男性6名,女性4名,年龄20~30岁,既往无神经、精神系统病史,实验期间被试保持闭眼静息。用3,1,0.5 Hz 3种不同频率的磁刺激刺激被试右手神门穴。每种频率的刺激实验分4组,第1组为静息实验,第2组为磁刺激实验,第3组为假刺激实验,第4组为假穴实验。观察4种状态下诱发电位的幅值与潜伏期,诱发电位偶极子源定位冠状面、矢状面和轴状面图。 结果与结论：0.5,1 Hz磁刺激实验4组状态的脑电信号均无明显诱发电位。3 Hz磁刺激安静状态与假刺激状态无诱发电位,磁刺激状态主要诱发产生P300成分,体感诱发电位和其他诱发电位得到抑制;假穴状态除产生P300,另外产生明显体感诱发电位和其他诱发电位。对刺激状态和假穴状态的脑电信号进行脑源定位,经过主成分分析确定有两个偶极子源,磁刺激状态偶极子源定位于额颞区,假穴状态偶极子分布较分散。说明采用磁刺激人体神门穴对脑电信号有明显抑制,与进行针刺或电刺激同样具有调节神经功能的作用。     

磁刺激穴位镇痛诱发的脑电信号特征成分及源定位

背景：针灸是中国传统医学的重要组成部分。穴位治疗作用是否具有生理基础或者只是心理作用一直是争议的焦点。目前临床中常用的穴位刺激方式为手针和电针,很少有关于磁刺激穴位引起脑电活动的文献发表。 目的：利用诱发电位来研究磁刺激合谷穴对大脑皮质功能区的影响,探讨磁刺激穴位镇痛机制。 方法：18名被试(男13名,女5名)自愿参加实验,选取右侧合谷穴作为靶点目标,距离合谷穴约3 cm处的非穴位点作为对照点。磁刺激频率为1Hz,刺激强度为1.76T,实验分别采集磁刺激前、中、后的脑电信号。 结果与结论：磁刺激穴位140~170 ms后,在F3,F1,FZ,F2,F4,FC3,FC1,FCZ,FC2,FC4 等电极处记录到诱发电位晚成分P150。对该成分进行偶极子源定位分析发现P150定位于前扣带回后部,之前的研究已经证明前扣带回不仅参与痛觉认知,还参与痛觉的调制。结果揭示了磁刺激穴位可能的镇痛机制。     

经颅磁刺激器设计及对毒品依赖者脑功能变化的评价

对经颅磁刺激进行了磁场强度分布的测试，分为3个方面，即分别对经颅磁刺激轴向和径向磁场强度的分布及在有效刺激区内的磁场最强圆周上磁场强度分布矢量值进行测试。在对毒品依赖者的康复实验中，将经颅磁刺激具体应用到对毒品依赖者进行治疗的实验测试中。磁刺激前，要记录毒品依赖者的脑电图，同时给患者不同的毒品图片进行视觉刺激。随后进行1个疗程的经颅磁刺激。之后，再用与第1次相同的视觉刺激序列，给患者看与经颅磁刺激治疗前相同的毒品图片，并记录患者的脑电数据，将前后2次的脑电数据经过一定步骤的处理后，将得出的刺激前后的N270波幅和潜伏期数据进行比较分析。经颅磁刺激刺激后毒品依赖者的N270振幅会有明显的降低，潜伏期会缩短，并且吸毒患者异常脑区的脑功能有所变化。毒品依赖者大部分存在差异的电极位于人的大脑的额叶区、颞叶区、顶叶和枕叶区，因此可以预测其大脑的额叶、颞叶、顶叶和枕叶可能受到海洛因的损害，该区域脑功能异于正常人。经过1个疗程经颅磁刺激刺激后，毒品依赖者的N270振幅和潜伏期都更接近正常人。因此，经颅磁刺激治疗对于海洛因依赖者有一定的疗效。     

经颅重复磁刺激的临床应用研究进展

经颅重复磁刺激(rTMS)是在经颅磁刺激基础上发展起来的新的神经电生理技术,具有检测和调节大脑皮质活性的作用,由于刺激参数和被刺激脑皮质区功能状态的不同,所引起的生物学效应也不同。rTMS通过改变大脑局部皮质兴奋性,改变皮质代谢及脑血流来达到治疗神经系统疾病的目的,其在精神疾病、癫痫、运动障碍疾病、脑梗死、脊髓损伤等治疗研究方面具有巨大的潜在价值。     

基于功率谱峰值及时变线性分类算法的运动意识分类

背景：脑电信号的特征提取是脑机接口系统中一个重要的环节,如何快速有效地提取反映大脑意识任务状态的脑电特征是进行分类、正确解读意识任务的关键。目前,提取脑电信号特征通常采用功率谱密度估计、自回归模型和小波变换等方法,这些特征都是以脑电信号的线性化为前提,上述方法不能很好地反映出大脑的非线性动力学性质。 目的：分析脑电信号功率谱峰值在识别左右手想象运动中的作用。 方法：采用脑机接口2003竞赛中Graz科技大学提供的脑电数据,用小波包分解获取8~24 Hz脑电信号,计算C3,C4电极脑电信号的功率谱峰值作为脑电特征向量,运用时变线性分类算法对运动意识任务运行分类。 结果与结论：对140次实验的测试样本进行数据分析,最大分类正确率可达89.29%,最大互信息和信噪比分别为0.626 9 bit和1.384 8。C3,C4电极8~24 Hz脑电信号功率谱峰值能很好地反映左右手运动想象脑电特征的变化,与事件相关去同步/事件相关同步现象变化一致,可在线识别左右手想象运动。     

功能性磁共振成像与针刺研究的基线选择

背景：功能性磁共振成像是近年发展起来研究穴位特异性的重要武器。目前大多数的针刺的功能性磁共振成像研究仍采用组块设计,而且绝大多数的都是在入针之后进行功能像扫描,认为入针后的静息段为纯静息,做为基线对照。但这与传统的针灸理论相冲突,因为传统针灸认为入针后也会出现入针效应。 目的：探讨如何选择针刺的功能性磁共振成像研究的基线。 方法：采用Hui的多组块设计,对入针后的效应进行相关分析,观察入针后是否有脑功能激活。 结果与结论：触觉刺激在刺激完成后,静息阶段不存在明显的脑功能变化;而针刺的入针时会产生一定的脑功能变化,入针后的静息段并非纯静息段。入针后的静息段也许不适于作基线。     

穴位配伍与脑区激活的关系：一项fMRI研究

临床上,穴位常配伍使用,但目前以健康人穴位穴位配伍针刺后进行脑功能成像的研究报道较少。实验运用功能性磁共振成像观察穴位配伍针刺后各脑区的不同激活现象。选用外关穴（SJ5）为主穴,针刺同名同经穴--支沟穴（SJ6）、表里经穴--内关穴（PC6）、同名异经穴--阳陵泉(GB34)以及非穴配穴（sham point）,并实时进行fMRI脑部扫描,分析比较各组脑区的激活概率、激活数量以及激活强度。结果证实,不同的穴位配伍对于脑区的激活有所不同,单纯针刺外关穴,能较为集中激活右侧小脑,配伍其他穴位后,能不同程度地激活不同脑功能区,此激活作用与不同穴位配伍组合有关。     

经颅磁刺激结合运动训练与局灶性脑梗死大鼠健侧感觉运动皮质锥体细胞树突和突触结构的改变

经颅磁刺激联合运动训练对脑梗死后健侧大脑感觉运动皮质突触和锥体细胞影响的报道几乎未见,实验拟揭示经颅磁刺激和运动训练促进脑梗死后运动功能恢复的机制。结果显示,经颅磁刺激和运动训练均能改善脑梗死大鼠神经功能,能使动物健侧感觉运动皮质锥体细胞突触界面曲率增加,突触后致密物厚度增加、突触间隙变窄,穿孔突触比例增加。经过4周经颅磁刺激和运动训练后脑梗死大鼠健侧感觉运动皮质区锥体细胞树突总长度、 一级数突分支和单位长度树突的树突棘密度明显增加,这些变化在经颅磁刺激和运动训练联合后更为明显。表明经颅磁刺激和运动训练治疗可以使健侧感觉运动皮质锥体细胞树突和突触结构参数发生改变,从而促使健侧脑的代偿作用,改善脑梗死大鼠的神经功能。     

不同思维状态下脑电近似熵的变化规律*

背景：近似熵是一种描述信号复杂性和规律性的非线性动力学方法,只需较少数据就能度量信号的复杂性。 目的：探讨不同思维状态下脑电近似熵的变化规律,以及近似熵在认知过程中的作用。 方法：用近似熵对20名健康成年人在安静闭眼、安静睁眼、闭眼记忆、闭眼心算和图片识别 5 种状态下的脑电数据进行分析。 结果与结论：近似熵值在闭眼计算和闭眼记忆思维状态高于安静闭眼状态,在图片识别状态下高于安静睁眼状态(P < 0.01);近似熵在安静闭眼和安静睁眼状态下各导联处于较低水平,在闭眼心算和闭眼记忆思维状态下各导联处明显增加。说明不同思维状态和不同导联部位对近似熵均有影响;近似熵在认知作业过程下较安静状态增高,并且不同思维状态下大脑功能活动的复杂性不同。因此脑电近似熵分析适用于认知过程脑功能活动变化规律研究,有助于了解大脑的工作机制。 关键词：近似熵;脑电;认知功能;思维状态;数字化医学     

针刺结合经颅磁刺激治疗偏头痛的疗效观察

目的观察针刺结合颅磁刺激治疗偏头痛的临床疗效。方法选取50例临床确诊的偏头痛患者,并随机分为观察组(针刺结合经颅磁刺激)和对照组(针刺组),每组25例。2组病人均予针刺法,观察组加用经颅磁刺激治疗。分别于治疗后第4周、第8周统计患者的偏头痛综合评分。结果与治疗前相比,2组患者疼痛程度均有明显改善(P0.05),但观察组有效率(92%)显著优于对照组(80%)(P0.05),治疗过程中2组患者均未出现明显身体不适。结论针刺结合经颅磁刺激治疗可显著改善偏头痛患者的疼痛综合评分,效果优于单用针刺治疗。     

Metabolic changes after repetitive transcranial magnetic stimulation (rTMS) of the left prefrontal cortex: a sham-controlled proton magnetic resonance spectroscopy (1H MRS) study of healthy brain

Rapid transcranial magnetic stimulation is being increasingly used in the treatment of psychiatric disorders, especially major depression. However, its mechanisms of action are still unclear. The aim of this study was to assess metabolic changes by proton magnetic resonance spectroscopy following high-frequency rapid transcranial magnetic stimulation (20 Hz), both immediately after a single session and 24 h after a series of five consecutive sessions. Twelve healthy volunteers were enrolled in a prospective single-blind, randomized study [sham (n = 5) vs. real (n = 7)]. Three brain regions were investigated (right, left dorsolateral prefrontal cortex, left anterior cingulate cortex). A single as well as a series of consecutive rapid transcranial magnetic stimulations affected cortical glutamate/glutamine levels. These effects were present not only close to the stimulation site (left dorsolateral prefrontal cortex), but also in remote (right dorsolateral prefrontal cortex, left cingulate cortex) brain regions. Remarkably, the observed changes in glutamate/glutamine levels were dependent on the pre-transcranial magnetic stimulation glutamate/glutamine concentration, i.e. the lower the pre-stimulation glutamate/glutamine level, the higher the glutamate/glutamine increase observed after short- or long-term stimulation (5 days). In general, the treatment was well tolerated and no serious side-effects were reported. Neither transient mood changes nor significant differences in the outcome of a series of neuropsychological test batteries after real or sham transcranial magnetic stimulation occurred in our experiment. In summary, these data indicate that rapid transcranial magnetic stimulation may act via stimulation of glutamatergic prefrontal neurons.     

不同穴位皮部浅刺与常规针刺在fMRI脑功能成像中的差异

Few studies have examined the effects of different stimuli at a single acupoint using functional magnetic resonance imaging.The present study applied acupuncture at the Neiguan(PC 6),Waiguan(SJ 5),Zhigou(SJ 6) and Yanglingquan(GB 34) acupoints in healthy volunteers.fMRI was used to examine the activation of brain areas in response to different types of acupuncture(cutaneous or routine acupuncture) at each acupoint.There were no significant differences in the distribution of activation in the regions of interest between cutaneous and routine acupuncture at the Neiguan,Waiguan,and Zhigou acupoints,but some differences were observed between the two methods of acupuncture at the Yanglingquan acupoint.There were no significant differences in the intensity of induced activation between cutaneous and routine acupuncture at the Neiguan,Zhigou and Yanglingquan acupoints,but the activation intensity in the right cerebellum induced by routine acupuncture at the Waiguan acupoint was greater than that induced by cutaneous acupuncture.Results confirmed that cutaneous and routine acupuncture at the Neiguan,Waiguan,Zhigou and Yanglingquan acupoints activated different functional brain areas,and caused activation of different intensities in some areas.     

Analysis of the effect of repeated-pulse transcranial magnetic stimulation at the Guangming point on electroencephalograms

Here, we administered repeated-pulse transcranial magnetic stimulation to healthy people at the left Guangming （GB37） and a mock point, and calculated the sample entropy of electroencephalo- gram signals using nonlinear dynamics. Additionally, we compared electroencephalogram sample entropy of signals in response to visual stimulation before, during, and after repeated-pulse tran- scranial magnetic stimulation at the Guangming. Results showed that electroencephalogram sample entropy at left （F3） and right （FP2） frontal electrodes were significantly different depending on where the magnetic stimulation was administered. Additionally, compared with the mock point, electroencephalogram sample entropy was higher after stimulating the Guangming point. When visual stimulation at Guangming was given before repeated-pulse transcranial magnetic stimula- tion, significant differences in sample entropy were found at five electrodes （C3, Cz, C4, P3, T8） in parietal cortex, the central gyrus, and the right temporal region compared with when it was given after repeated-pulse transcranial magnetic stimulation, indicating that repeated-pulse transcranial magnetic stimulation at Guangming can affect visual function. Analysis of electroencephalogram revealed that when visual stimulation preceded repeated pulse transcranial magnetic stimulation, sample entropy values were higher at the C3, C4, and P3 electrodes and lower at the Cz and T8 electrodes than visual stimulation followed preceded repeated pulse transcranial magnetic stimula- tion. The findings indicate that repeated-pulse transcranial magnetic stimulation at the Guangming evokes different patterns of electroencephalogram signals than repeated-pulse transcranial mag- netic stimulation at other nearby points on the body surface, and that repeated-pulse transcranial magnetic stimulation at the Guangrning is associated with changes in the complexity of visually evoked electroencephalogram signals in parietal regions, central gyrus, and temporal regions.     

Brain activity underlying visual perception and attention as inferred from TMS-EEG: a review

Probing brain functions by brain stimulation while simultaneously recording brain activity allows addressing major issues in cognitive neuroscience. We review recent studies where electroencephalography (EEG) has been combined with transcranial magnetic stimulation (TMS) in order to investigate possible neuronal substrates of visual perception and attention. TMS–EEG has been used to study both pre-stimulus brain activity patterns that affect upcoming perception, and also the stimulus-evoked and task-related inter-regional interactions within the extended visual-attentional network from which attention and perception emerge. Local processes in visual areas have been probed by directly stimulating occipital cortex while monitoring EEG activity and perception. Interactions within the attention network have been probed by concurrently stimulating frontal or parietal areas. The use of tasks manipulating implicit and explicit memory has revealed in addition a role for attentional processes in memory. Taken together, these studies helped to reveal that visual selection relies on spontaneous intrinsic activity in visual cortex prior to the incoming stimulus, their control by attention, and post-stimulus processes incorporating a re-entrant bias from frontal and parietal areas that depends on the task.     

EEG modification induced by repetitive transcranial magnetic stimulation.

Repetitive transcranial magnetic stimulation (rTMS) is a powerful, noninvasive tool for investigating cortical physiologic functions in the brain. However, EEG spectral analysis has not been investigated extensively in rTMS study. The authors investigated the influence of rTMS on the EEG power spectrum by stimulating the left frontal cortex in 32 healthy subjects. Stimulation parameters were a 10-Hz frequency, a 3-second duration, and a 100% motor threshold. The data showed that rTMS increased the peak frequency of EEG across the scalp within 2 minutes after stimulation, whereas the value decreased at 3 to 4 minutes. The mean absolute powers within 3 minutes after rTMS did not differ from those estimated before rTMS, but increased uniformly at 4 to 5 minutes. The spectra did not change after sham stimulation. These results indicate that rTMS can influence cortical activities significantly by increasing the frequency and amplitude of EEG, and is a useful tool for helping us understand brain functions.     

电针刺激脊髓损伤患者穴位的脊髓磁共振功能成像激活区特征****☆

背景：研究发现脊髓功能激活区域和电生理等理论对应区域相一致,多数学者认为使用功能磁共振技术检测脊髓神经功能是可行的。 目的：检测电针刺激脊髓损伤患者的脊髓磁共振功能成像激活区特征,验证使用脊髓磁共振功能成像技术来客观评价针灸治疗脊髓损伤疗效的可行性。 方法：使用电针同时刺激3例脊髓损伤患者和5名健康志愿者的右手合谷穴和曲池穴,采用组块设计方法,使用SPM2软件得到患者和健康志愿者脊髓内真实的激活区,分析激活区在矢状位和横断位上的分布特征,并与健康志愿者的激活分布对比,找出患者的激活分布差异。 结果与结论：5名健康志愿者在脊柱C2、C5段均重复出现激活信号,在C6段4名出现激活;3例脊髓损伤患者在脊柱C2,C6段均出现均重复出现激活,其中1例患者与健康志愿者激活分布特征基本一致。可以观察到针灸刺激脊髓损伤患者的脊髓功能激活,因此可以根据功能激活区的分布及强度,在一定程度上客观评价针灸治疗脊髓损伤的疗效。 关键词：磁共振功能成像;脊髓损伤;针灸;穴位;SEEP;数字化图像与影像     

A new device and protocol for combining TMS and online recordings of EEG and evoked potentials

We describe an electroencephalographic (EEG) device and protocol that allows recording of electrophysiological signals generated by the human brain during transcranial magnetic stimulation (TMS) despite the TMS-induced high-voltage artifacts. The key hardware components include slew-rate limited preamplifiers to prevent saturation of the EEG system due to TMS. The protocol involves artifact subtraction to isolate the electrophysiological signals from residual TMS-induced contaminations. The TMS compatibility of the protocol is illustrated with examples of two data sets demonstrating the feasibility of the approach in the single-pulse TMS design, as well as during repetitive TMS. Our data show that both high-amplitude potentials evoked by visual checkerboard stimulation and low-amplitude steady-state oscillations induced by auditory click-trains can be retrieved with the present protocol. The signals recorded during TMS perfectly matched control EEG responses to the same visual and auditory stimuli. The main field of application of the present protocol is in cognitive neuroscience complementing behavioral studies that use TMS to induce transient, 'virtual lesions'. Combined EEG-TMS techniques provide neuroscientists with a unique method to test hypothesis on functional connectivity, as well as on mechanisms of functional orchestration, reorganization, and plasticity.     

Chaos or noise in EEG signals; dependence on state and brain site.

EEG signals have been considered to result either from random processes or to be generated by non-linear dynamic systems exhibiting chaotic behaviour. In the latter case, the system may behave as a deterministic chaotic attractor. The complexity of the attractor can be characterized by the correlation dimension that can be computed from one signal generated by the system. A new procedure was developed and applied in order to test whether the correlation dimension, calculated from an EEG epoch, may correspond to a chaotic attractor or to a random process. This procedure was applied to EEG signals recorded from different sites of the limbic cortex of the rat during different states: wakeful rest, locomotion and in the course of an epileptic seizure induced by kindling. The signals recorded during the first two states had high dimensions and could not be distinguished from random noise. However, during an epileptic seizure the correlation dimension became low (between 2 and 4) indicating that in this state the networks behave as chaotic systems. A low correlation dimension appeared at different times and brain sites during an epileptic seizure. These results show that the computation of the correlation dimension may be useful in order to obtain insight into the dynamics of the propagation of an epileptic seizure in the brain.