高频电刺激大鼠丘脑底核抑制背侧中缝核5-羟色胺表达

本研究探讨高频电刺激丘脑底核对大鼠背侧中缝核5-羟色胺(5-HT)表达的影响。实验动物分两组,刺激组给予高频电流(130Hz,100μA,60μs)刺激大鼠右侧丘脑底核,对照组大鼠右侧丘脑底核植入电极,但无电流输出。刺激结束后,用免疫组织化学方法染色背侧中缝核5-HT能神经元,检测背侧中缝核5-HT能神经元的数量和平均灰度值。结果显示电刺激组背侧中缝核5-HT阳性神经元数目与对照组比明显减少(t(13)=3.786,P=0.002),并且神经递质5-HT表达量减少,平均灰度值显著增高(t(13)=7.917,P<0.001)。本实验结果表明高频电刺激丘脑底核对背侧中缝核5-HT能神经元有抑制作用,在应用高频电刺激丘脑底核治疗Parkison病运动障碍时出现的情绪障碍可能与其有关。     

利用低频脉冲磁场诱导入眠的实验研究

经皮磁刺激是近几年来新兴的一个研究领域。本研究试图通过自行设计的磁场发生装置将模拟脑电节律的外界低频脉冲磁场耦合入实验动物猫的脑内，由感生的电信号影响其脑电活动，并诱导其入眠。实验结果表明：该磁场能够耦合入动物脑内并有效地影响了脑电活动。这种诱导磁刺激有显著的促进入眠作用。     

刺激中缝核对海马单元放电的影响(摘要)

我们以往的工作证明,海马结构内存在痛敏神经元和痛抑制神经元。它们的电活动受电针穴位和外源性吗啡类物质的影响。近来的研究资料表明,中缝核群是脑内5—羟色胺(5—HT)神经元的主要集中地。本工作的目的在于探讨刺激5—HT—神经元对海马单元放电的影响,以了解它在痛调制中的作用。实验用健康家猫20只,雌雄不分。乙醚麻醉下手术,用箭毒制动,在人工呼吸条件下用约40伏的方波脉冲刺激隐神经作为痛刺激;用充以3Mkcl溶液的玻璃微电极在对侧的海马结     

重复经颅磁刺激显著改善小鼠老化过程中认知损伤及提高神经元兴奋性

重复经颅磁刺激是一种无创的脑刺激技术,作为一种治疗性神经康复手段备受关注。已有研究表明,高频重复经颅磁刺激可以提高动物在行为测试中的认知能力和神经元兴奋性。本文旨在研究小鼠自然老化过程中,高频重复经颅磁刺激对其认知能力和神经兴奋性的影响。实验采用青年小鼠、成年小鼠、老年小鼠各12只,且每个年龄段小鼠被随机分成刺激组和对照组。刺激组小鼠接受连续15天的高频重复经颅磁刺激,对照组接受连续15天的伪刺激。刺激结束之后,进行新物体识别与跳台测试,用以检查小鼠的学习记忆能力。行为学测试结束之后,进行全细胞脑片膜片钳实验,用以记录并分析海马齿状回颗粒神经元的静息膜电位、动作电位及其相关电特性指标。数据分析表明,小鼠认知能力与神经兴奋性随着老化而显著衰退,高频重复经颅磁刺激能显著改善认知损伤并缓解神经电特性指标的衰退。通过改变海马齿状回颗粒神经元电生理特性以及提高神经元兴奋性,可能是重复经颅磁刺激缓解认知损伤、提高认知能力的机制之一。     

经颅磁声电刺激影响大鼠工作记忆中局部场电位的相位幅值耦合分析EI北大核心CSCD

经颅磁声电刺激是一种新型无创的神经调控手段,其利用超声与静磁场耦合作用产生的感应电场调节相应脑区神经节律振荡活动。本文旨在探讨经颅磁声电刺激对记忆过程中神经元集群信息传递与交流的影响。实验中,将20只健康成年维斯塔尔(Wistar)大鼠随机分为对照组(5只)和刺激组(15只),对刺激组施加0.05~0.15 T、2.66~13.33 W/cm2的经颅磁声电刺激,对照组不施加刺激;采集大鼠执行T迷宫工作记忆任务中前额叶皮层的局部场电位信号,比较不同参数刺激组大鼠与对照组大鼠delta节律相位、theta节律相位与gamma节律幅值之间的耦合差异性。实验结果显示,刺激组delta节律与gamma节律的耦合强度明显低于对照组(P<0.05),theta节律与gamma节律的耦合强度明显高于对照组(P<0.05);随着刺激参数的增加,delta节律与gamma节律、theta节律与gamma节律耦合程度分别呈现减小、增大的趋势。本文初步研究结果表明,经颅磁声电刺激能够抑制前额叶皮层中delta节律神经活动,增强theta节律与gamma节律振荡活动,从而促进了不同空间范围内神经元集群之间的信息交流与传递,这为进一步探索经颅磁声电刺激调节大脑记忆功能的作用机制奠定了基础。     

TMS线圈与EEG电极线相对位置对TMS-EEG信号的影响

通过分析经颅磁刺激线圈放电时的电场分布,探索磁刺激输出脉冲对脑电采集帽产生的伪迹信号来源。我们通过建立八字线圈感应电场分布的半无界空间数学模型,获得八字线圈感应电场的分布特性,分析磁刺激影响脑电采集回路的两种影响因素,我们用matlab软件仿真刺激线圈与脑电极线成不同角度、不同距离时产生的伪迹信号的变化趋势,通过模型试验和人体实验验证这种趋势的准确性;结果显示,脑电导线重合于线圈长轴,产生脑电伪迹最小,当线圈转动其他角度或当线圈下移时伪迹会逐渐增大,最大伪迹幅值是最小伪迹幅值的约10倍。在TMS-EEG试验中,伪迹信号的幅值、持续时间与线圈摆放位置、角度有关。通过实验前合理排布脑电极线可降低伪迹信号幅值、持续时间等参数,提高磁刺激下脑电信号特征信号提取的准确性。     

脉冲磁场对大鼠记忆能力和海马神经递质的影响

本文用低频脉冲磁场和被调制的高频脉冲磁场刺激大鼠，研究不同磁场对大鼠记忆能力及脑内神经递质的影响，探讨其作用机制。研究结果表明，高频脉冲磁场和低频脉冲磁场对大鼠的记忆能力都产生明显影响，但随着时间延长，这种影响逐渐消失；与对照组比较，刺激组大鼠海马去甲肾上腺素（NE）、多巴胺（DA）及5－羟色胺（5－HT）含量增加；乙酰胆碱（ACh）含量减少。脉冲磁场能够影响海马神经递质释放，降低大鼠记忆能力。     

刺激中缝核电、电泳5—HT红藻氨酸所致海马痫样放电的影响

本实验采用侧脑室注射红藻氨酸造成大鼠癫痫发作,用多管微电极记录背海马的痫样放电。继而刺激延髓中缝核区,微电泳5—HT,观察海马癫样放电和海马脑电的变化,以探讨内、外源性5HT对海马痫样放电的作用。大鼠海马CA_1区共记录62个癫样放电单位。电刺激中缝核后1min内,     

电刺激大鼠小脑顶核对下丘脑神经元放电活动的影响

目的:研究电刺激小脑顶核(fastigial nucleus,FN)及微电泳Glu(glutamic acid)、MK-801对大鼠下丘脑(hypothalamus,HT)神经元自发放电活动的影响,探讨电刺激FN治疗脑卒中大鼠的机制。方法:应用细胞外记录的方法,记录电刺激FN及微电泳药物对HT神经元放电的影响。结果:电刺激频率为20Hz(低频)时,50%的HT神经元的放电频率增高(P0.01),电刺激频率为100Hz(高频时),80%的HT神经元的放电频率增高(P0.01);Glu对HT有紧张性兴奋作用,其拮抗剂MK-801能够明显抑制Glu诱致的兴奋作用;70%HT神经元在微电泳MK-801的基础上进行100Hz电刺激FN时,高频刺激诱发的兴奋作用被明显削弱。结论:采用电刺激FN治疗脑卒中,其可能机制是通过Glu的兴奋作用来调节HT的异常活动。     

基于节律同化效应的思维脑电信号分类研究

通过对正弦调制光（SML）刺激和无刺激思维脑电信号的对比分类研究，探索了思维脑电信号的节律同化现象对思维脑电信号分类的影响。研究结果表明，大脑在SML刺激下进行思维作业时，思维EEG信号携带的与刺激频率有关的节律同化信息能提高某些思维作业的分类正确率，并且SML刺激产生的局部节律同化效应能减少用于提供分类信息的EEG信号的导联数。这些结果有利于提高基于思维作业脑-计算机接口（BCI）的通信准确率和速度。     

Sleep EEG alterations: effects of pulsed magnetic fields versus pulse‐modulated radio frequency electromagnetic fields

Studies have repeatedly shown that electroencephalographic power during sleep is enhanced in the spindle frequency range following radio frequency electromagnetic field exposures pulse‐modulated with fundamental frequency components of 2, 8, 14 or 217 Hz and combinations of these. However, signals used in previous studies also had significant harmonic components above 20 Hz. The current study aimed: (i) to determine if modulation components above 20 Hz, in combination with radio frequency, are necessary to alter the electroencephalogram; and (ii) to test the demodulation hypothesis, if the same effects occur after magnetic field exposure with the same pulse sequence used in the pulse‐modulated radio frequency exposure. In a randomized double‐blind crossover design, 25 young healthy men were exposed at weekly intervals to three different conditions for 30 min before sleep. Cognitive tasks were also performed during exposure. The conditions were a 2‐Hz pulse‐modulated radio frequency field, a 2‐Hz pulsed magnetic field, and sham. Radio frequency exposure increased electroencephalogram power in the spindle frequency range. Furthermore, delta and theta activity (non‐rapid eye movement sleep), and alpha and delta activity (rapid eye movement sleep) were affected following both exposure conditions. No effect on sleep architecture and no clear impact of exposure on cognition was observed. These results demonstrate that both pulse‐modulated radio frequency and pulsed magnetic fields affect brain physiology, and the presence of significant frequency components above 20 Hz are not fundamental for these effects to occur. Because responses were not identical for all exposures, the study does not support the hypothesis that effects of radio frequency exposure are based on demodulation of the signal only.     

基于不同闪烁频率光刺激的脑电压变化研究

目的：脑电信号是大量神经元电活动在大脑头皮表面产生的电位总和,可综合反映大脑内部功能状态和活跃程度。当人体受到外界刺激时,神经系统产生一系列复杂的生物电活动,最终反映为脑电信号。本文使用不同闪烁频率光为刺激源,对光刺激前后脑电信号时域和频域的变化特性进行分析,为利用外刺激调制脑电频率提供新的实验依据。方法：使用同一光源,分别改变其闪烁频率对受试者眼睛进行刺激,利用脑立方移动版采集不同闪烁频率光刺激下的脑电信号,记录并分析脑电信号电位幅值,及其成份δ波（1 Hz~3 Hz）、θ波（4 Hz~7 Hz）、α波（8 Hz~13 Hz）和β波（14Hz~30Hz）能量的变化情况。结果：随着光闪烁频率的增高,脑电压幅度均值和各频段能量先逐渐增大后减小,脑电幅值和各频段能量均在光闪烁频率为5 Hz时达到最大。结论：不同闪烁频率光刺激对脑电压的变化具有显著性影响：在一定阈值之下,脑电压与光闪烁频率变化一致;超过阈值后,趋势相反。该结论有助于探索脑电信号在外刺激作用下的变化规律,为利用外刺激治疗脑部疾病的方式提供了参考价值。     

连续经颅磁刺激睡眠仪系统的设计

目的为了寻求合适的经颅磁刺激模式治疗失眠等神经系统类的疾病,设计出一种新型的连续经颅磁刺激系统。方法采用PC和单片机交互控制,改进后级TDA7294功放电路,实现0.001Hz～20.000kHz的连续大功率输出驱动线圈产生交变磁场。结果实现了将真实睡眠脑电信号、音乐信号及几种典型波形的刺激信号转换成空间交变磁场直接耦合进大脑的睡眠中枢,同时对圆形线圈在真实头模型下的磁场和感应电流分布进行了有限元仿真。结论系统达到了预定指标,为进一步临床研究提供了可靠的实验平台。     

低频光诱发脑电在浅睡期的样本熵复杂度分析

睡眠障碍患者通常表现为从浅睡期进入深睡期存在困难,分析浅睡期脑电波的变化对研究睡眠效率和睡眠质量至关重要。通过分析低频光刺激下睡眠过程中脑电波的复杂度值变化,研究人在浅睡期脑电波对光刺激的响应,进而探讨外部光刺激对睡眠过程中脑电波的影响。使用美国neuroscan型脑电图仪,采集10例志愿者的光刺激睡眠和正常睡眠的脑电数据。首先,利用时频分析,对睡眠过程中的脑电信号进行分期,获得浅睡期脑电信号;然后,使用小波包分解,获得该期脑电波的各频段分量（δ波、θ波、α波和纺锤波）;接着,采用样本熵算法,分别计算浅睡期脑电信号的复杂度以及各频段脑电波的复杂度;最后,对志愿者在光刺激（5 Hz）和正常睡眠下浅睡期脑电复杂度进行比较,研究光刺激对脑电复杂度的响应情况。结果显示：在低频光刺激下,浅睡期脑电波复杂度的均值为0514 15,明显低于正常睡眠复杂度的均值0589 23,在中央区和顶区有显著性差异（P<005）。研究表明,5 Hz光刺激可诱发浅睡期θ波的同步响应,增强脑电波的节律性,有助于更好地进入深度睡眠。     

用于神经细胞实验研究的低频交变磁场发生器的研制

本文介绍了一种用于神经细胞实验研究的低频磁场波形发生器。目的：为低频磁场辐照与肿瘤实验提供工具。材料与方法：采用单片机控制，用户手动选择参数。输出一定波形，强度和占空比的信号，经功放电路放大后得到低频磁场。本文将详细讨论仪器中波形发生的部分。结果：本仪器磁场强度最高可达100mT，频率0-500Hz。结论：仪器完全满足实验需要。     

Physiological properties of raphe magnus neurons during sleep and waking

Neurons in the medullary raphe magnus (RM) that are important in the descending modulation of nociceptive transmission are classified by their response to noxious tail heat as ON, OFF, or NEUTRAL cells. Experiments in anesthetized animals demonstrate that RM ON cells facilitate and OFF cells inhibit nociceptive transmission. Yet little is known of the physiology of these cells in the unanesthetized animal. The first aim of the present experiments was to determine whether cells with ON- and OFF-like responses to noxious heat exist in the unanesthetized rat. Second, to determine if RM cells have state-dependent discharge, the activity of RM neurons was recorded during waking and sleeping states. Noxious heat applied during waking and slow wave sleep excited one group of cells (ON-U) in unanesthetized rats. Other cells were inhibited by noxious heat (OFF-U) applied during waking and slow wave sleep states in unanesthetized rats. NEUTRAL-U cells did not respond to noxious thermal stimulation applied during either slow wave sleep or waking. ON-U and OFF-U cells were more likely to respond to noxious heat during slow wave sleep than during waking and were least likely to respond when the animal was eating or drinking. Although RM cells rarely respond to innocuous stimulation applied during anesthesia, ON-U and OFF-U cells were excited and inhibited, respectively, by innocuous somatosensory stimulation in the unanesthetized rat. The spontaneous activity of >90% of the RM neurons recorded in the unanesthetized rat was influenced by behavioral state. OFF-U cells discharged sporadically during waking but were continuously active during slow wave sleep. By contrast, ON-U and NEUTRAL-U cells discharged in bursts during waking and either ceased to discharge entirely or discharged at a low rate during slow wave sleep. We suggest that OFF cell discharge functions to suppress pain-evoked reactions during sleep, whereas ON cell discharge facilitates pain-evoked responses during waking.     

Muscle artifacts in the sleep EEG: Automated detection and effect on all-night EEG power spectra

Owing to the use of scalp electrodes in human sleep recordings, cortical EEG signals are inevitably intermingled with the electrical activity of the muscle tissue on the skull. Muscle artifacts are characterized by surges in high frequency activity and are readily identified because of their outlying high values relative to the local background activity. To detect bursts of myogenic activity a simple algorithm is introduced that compares high frequency activity (26.25–32.0 Hz) in each 4-s epoch with the activity level in a local 3-min window. A 4-s value was considered artifactual if it exceeded the local background activity by a certain factor. Sensitivity and specificity of the artifact detection algorithm were empirically adjusted by applying different factors as artifact thresholds. In an analysis of sleep EEG signals recorded from 25 healthy young adults 2.3% (SEM: 0.16) of all 4-s epochs during sleep were identified as artifacts when a threshold factor of four was applied. Contamination of the EEG by muscle activity was more frequent towards the end of non-REM sleep episodes when EEG slow wave activity declined. Within and across REM sleep episodes muscle artifacts were evenly distributed. When the EEG signal was cleared of muscle artifacts, the all-night EEG power spectrum showed significant reductions in power density for all frequencies from 0.25–32.0 Hz. Between 15 and 32 Hz, muscle artifacts made up a substantial part (20–70%) of all-night EEG power density. It is concluded that elimination of short-lasting muscle artifacts reduces the confound between cortical and myogenic activity and is important in interpreting quantitative EEG data. Quantitative approaches in defining and detecting transient events in the EEG signal may help to determine which EEG phenomena constitute clinically significant arousals.     

经颅磁声电刺激对前额叶皮层神经集群钙信号的影响EI北大核心CSCD

经颅磁声电刺激(TMAES)作为一种新型的脑神经调控和研究手段,利用超声和磁场耦合产生的感应电流调节不同脑区的神经电活动。钙离子作为神经信号第二特使,在神经信号传递中起着关键作用。为了探究经颅磁声电刺激对前额叶皮层放电活动的影响,将15只小鼠分为对照组、超声组和磁声组,磁声组接受超声强度为2.6 W/cm^(2)和磁感应强度为0.3 T的刺激,超声组仅接受相同强度的超声刺激,对照组无超声和磁场,持续刺激一周。通过光纤光度检测技术实时记录小鼠刺激过程中前额叶皮层钙离子浓度,并进行新物体识别实验,对比各组行为学差异和钙信号的时频分布。实验结果显示,经颅磁声组在刺激后10 s内钙瞬变信号均值(4.84±0.11)%大于超声组(4.40±0.10)%和对照组(4.22±0.08)%,且钙瞬变信号波形变缓,提示钙离子代谢变快;磁声组主要能量频带分布在0~20 Hz,超声组为0~12 Hz,对照组为0~8 Hz;磁声组认知指数为0.71,超声组为0.63,对照组为0.58,表明超声刺激和磁声电刺激均能提高小鼠的认知能力,但磁声组效果优于超声组。以上结果显示,经颅磁声电刺激能够改变前额叶皮层神经集群的钙稳态,实现对前额叶神经集群放电活动的调控,对认知功能具有促进效果。研究结果为进一步探索经颅磁声电刺激的深层神经作用机制提供了数据支撑和参考。     

Segmentation and tracking of the electro-encephalogram signal using an adaptive recursive bandpass filter

An adaptive filtering approach for the segmentation and tracking of electro-encephalogram (EEG) signal waves is described. In this approach, an adaptive recursive bandpass filter is employed for estimating and tracking the centre frequency associated with each EEG wave. The main advantage inherent in the approach is that the employed adaptive filter has only one unknown coefficient to be updated. This coefficient, having an absolute value less than 1, represents an efficient distinct feature for each EEG specific wave, and its time function reflects the non-stationarity behaviour of the EEG signal. Therefore the proposed approach is simple and accurarate in comparison with existing multivariate adaptive approaches. The approach is examined using extensive computer simulations. It is applied to computer-generated EEG signals composed of different waves. The adaptive filter coefficient (i.e. the segmentation parameter) is −0.492 for the delta wave, −0.360 for the theta wave, −0.191 for the alpha wave, −0.027 for the sigma wave, 0.138 for the beta wave and 0.605 for the gamma wave. This implies that the segmentation parameter increases with the increase in the centre frequency of the EEG waves, which provides fast on-line information about the behaviour of the EEG signal. The approach is also applied to real-world EEG data for the detection of sleep spindles.     

Cortical evoked responses to magnetic stimulation of macaque's abdominal wall in sleep-wake cycle

EEG and eye movements (magnetic search coil method) were recorded in sleep and wakefulness in a monkey (Macaca fascicularis) while the animal was sitting in a primate chair. Single pulse magnetic stimulation was applied to the monkey's abdominal wall using a circular coil and a Magstim 200 stimulator. Magnetic stimuli did not wake the sleeping animal, and being applied during slow wave sleep evoked clear responses in EEG with a latency of 80-100 ms. These responses disappeared during wakefulness and rapid eye movement sleep. Control experiments confirmed that these responses were not caused by the acoustic clicks produced by the magnetic coil. Results of this study further confirm that during sleep, signals from visceral organs reach the cortical areas which in wakefulness process exteroceptive sensory information. This observation indicates that magnetic stimulation may be a useful tool for researching neural connectivity reorganization within the sleep-wake cycle.