经颅磁声耦合电刺激技术应用于小鼠的实验研究

研究经颅磁声耦合刺激技术(transcranial magneto-acoustic stimulation,TMAS)在体小动物脑神经刺激效果。搭建了针对小动物模型的TMAS系统。设置TMAS系统参数,对健康鼠及帕金森(parkinson's disease,PD)模型鼠进行经颅聚焦磁声刺激实验,并分析行为学及电生理结果。经过TMAS刺激后,行为学结果表明磁声刺激组小鼠在主动探索学习能力和运动能力显著高于对照组;电生理结果表明TMAS刺激后PD模型鼠海马区黑质神经突触活性提高。实验结果验证了TMAS技术对小鼠脑神经刺激的有效性。该技术的进一步研究将具有更好的应用前景。     

视觉听觉同时刺激模式下ERP的同步性研究

目的：研究视觉、听觉脑区在认知过程中的同步性。方法：设计了视觉、听觉同时刺激模式下的脑电实验，采用128道高密度脑电采集系统，记录了14位年龄在18～29岁之间的在校男性大学生的诱发脑电信号数据，并运用希尔伯特(Hilbert)相位同步算法对视觉、听觉区域的事件相关电位(ERP)进行同步量化。结果：在视听觉同时利用模式下，视觉脑区(枕叶)和听觉脑区(颞叶)之间的同步指数明显大于它们与其他脑区间的同步指数。结论：人在感知和认知事物时，相关的脑区间自动产生了神经活动的同步化。     

异氟烷麻醉对小鼠自发肌电及TUS/TMAS诱发肌电的影响

经颅超声刺激(TUS)和经颅磁声耦合刺激(TMAS)调控运动皮层效果明显,但受限于清醒状态动物难以束缚,已有研究大多在麻醉状态下进行,对麻醉减弱调控效果的分析集中于中枢神经系统。本研究记录了异氟烷麻醉下24只小鼠的肢体自发肌电和TUS/TMAS诱发肌电,定量分析了麻醉对自发肌电和诱发肌电发放率、潜伏期、时长和幅值的影响。结果显示,随着异氟烷输出浓度从0.40%增加至0.75%,每周期内小鼠自发肌电频次减少约50%,肌电发放时长变短,呈抑制状态;TUS/TMAS诱发肌电的成功率分别降低约50%和70%、潜伏期均延长约0.1 s、时长分别缩短约0.3和0.5 s,表明TUS/TMAS对运动皮层的调控效果随麻醉程度的加深而减弱。肢体自发和诱发肌电在发放率和时长上存在关联性特征,提示麻醉状态下小鼠自发肌电抑制状态可能是刺激效果减弱的影响因素之一。     

听视觉刺激对长期听力损失患者语言处理的影响

目的:研究听视觉刺激对听力损失患者大脑中与语言处理相关脑区神经活动的影响,为患者的康复治疗提供理论支撑。方法:募集12个听力损失患者和12个性别年龄匹配的正常听力受试者。首先构建每个参与者个体化虚拟数字脑,然后将虚拟视觉刺激信号施加到已构建虚拟数字脑的次级视觉皮层;将虚拟听觉刺激信号施加到已构建虚拟数字脑的初级听觉皮层。最后,观察这些刺激信号在听力损失患者脑皮层中所诱发的神经活动变化。结果:同正常受试者相比,虚拟视觉刺激信号抑制了听力损失患者听觉皮层和布洛卡区的神经活动,并通过最短因果路径削弱了布洛卡区的激活。相反,虚拟听觉刺激信号抑制了听力损失患者视觉皮层的激活,但通过最短因果路径增强了布洛卡区的神经活动。此外,听力损失患者也呈现了减弱的视觉诱发的威尼克区的激活。结论:目前的研究表明,视觉刺激通过削弱听觉皮层和布洛卡区的神经活动抑制了听力损失患者的语言处理。相反,听觉刺激通过抑制视觉皮层的活动,增强布洛卡区的神经活动,从而改善了听力损失患者的语言处理。     

视听联合刺激的跨感觉通道诱发电位源的分析

运用偶极子源分析方法分析视听单独刺激和联合刺激下脑区的区别和联系.采用64道脑电采集系统,记录了7名被试者在视觉、听觉和视听联合刺激下的脑诱发电位,并分别在初期、早期和晚期时间段对这3种任务做偶极子源分析.通过比较视听联合刺激和视听单独刺激下偶极子源的变化,可以得到视听联合刺激下的源不等于单独视听刺激下的源的简单叠加,从而提示存在视听相互作用的区域.     

经颅磁刺激在时间认知研究中的应用

经颅磁刺激(TMS)可以暂时性地改变特定大脑区域的神经活动以研究该脑区在时间认知中的作用。高频TMS通常增加皮质兴奋性,用高频TMS刺激右侧背外侧前额皮质可以影响秒范围的时距知觉,刺激小脑可以影响毫秒范围的时距知觉。经颅磁刺激可以作为探讨时间认知神经机制的有效工具,并可以作为脑损伤病人改善时间认知能力的有效治疗手段。     

手肌反射及其临床意义

通过各种各样的刺激可以在手部或臀部肌肉诱发出一些反射．被称之为手肌反射。目前研究的刺激方式有：①肌肉的牵张刺激；②采用气流团对皮肤刺激；⑧对混合或单纯表浅神经的电刺激。手肌反射常呈现出多样反射波．这些反射活动很可能是通过不同的神经反射通路来完成，基于这些不刷的反射通路．在一块肌肉上获得这些反射往往很困难或不太可能。下面将手肌反射的方法学、生理机制以及在一些神经系统疾痫的临床应用作一简要介绍。     

经颅电刺激技术用于运动表现提升的研究进展

经颅电刺激(TES)包括经颅直流电刺激、经颅交流电刺激和经颅随机噪声刺激,是一种非侵入的脑刺激技术。通过不同尺寸的电极将特定模式的低强度电流作用于特定的脑区,调节大脑皮质神经活动和/或兴奋性,增强大脑与神经、肌肉的连接,达到改善运动表现的作用。目前TES技术正在实现从实验室研究到运动科学应用研究的转变。首先阐述TES作用于大脑皮质的神经机制,着重评述近20年来TES在人类运动表现提升方面的研究进展,包括身体平衡、耐力表现、运动疲劳、肌肉力量和运动学习能力等5个方面;然后综述TES在脑网络功能连通性中应用的相关研究,并探讨该领域对TES改善运动表现的重要意义; 最后对TES在运动表现提升中的应用研究进行展望。     

经颅电刺激用于深脑刺激的研究进展

经颅电刺激（TES）是一种无创、经济、耐受性好的神经调控技术。但是，传统TES为全脑性刺激，且刺激电流较小，无法满足临床治疗中对深部脑区的有效聚焦刺激的需求。随着TES技术临床应用的不断深入，研究人员不断探索出新的刺激方法来提高刺激聚焦性、刺激强度和刺激深度，尤其是以高精度经颅电刺激、时间干涉刺激为代表的多电极刺激研究已展开。本文回顾了近年来TES的优化方案，并进一步分析了现有刺激方法的特点和局限，以期为相关临床应用提供借鉴和参考，并为后续研究提供指导。此外，本文还对TES未来发展趋势进行了展望，并提出了可能用于深脑刺激的TES优化方向，以期能为后续研究和应用提供新的思路。     

用于磁声耦合刺激的64阵元相控阵超声换能器的设计

本研究基于磁声耦合刺激技术(transcranial magneto-acoustic stimulation,TMAS)的需求,设计了用于线性64阵元相控阵的超声换能器,探究相控阵超声换能器压电晶体宽度及间距,优化超声换能器聚焦声场分布.采用MATLAB软件建立相控阵换能器模型,仿真聚焦声场分布.搭建三维声场分布测试...     

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。     

经颅磁声电刺激下大鼠工作记忆中前额叶皮层因果连接网络特性分析

经颅磁声电刺激(TMAES)是一种新型非侵入式的脑神经调控技术，利用静磁场和超声波耦合在脑组织中产生刺激电流以调节特定脑区的神经放电活动。本研究旨在从神经节律振荡与信息传递的角度，探究经颅磁声电刺激对大脑工作记忆功能的影响。将24只斯普拉格·道利(SD)大鼠随机分为对照组、超声组和磁声组，磁声组接受0.10 T、7.98 W/cm²的刺激，超声组接受相同强度的超声刺激，对照组不接受刺激；采集T迷宫工作记忆实验中大鼠前额叶皮层的局部场电位(LFPs)信号，对比不同组别θ(4～8 Hz)和γ(30～80 Hz)频段LFPs信号的时频分布，并基于图论进一步分析前额叶皮层的因果连接网络特性。结果显示，磁声组大鼠在行为选择过程中θ和γ频段LFPs信号的能量值大于超声组与对照组(P<0.05);磁声组信号间平均因果连接强度高于超声组和对照组(P<0.05);磁声组大鼠工作记忆任务中θ频段因果连接网络的全局效率(E_glob)和聚类系数(C)比超声组和对照组显著升高(磁声组：E_glob=0.134±0.033,C=0.837...     

Depressed mood, index finger force and motor cortex stimulation: a transcranial magnetic stimulation (TMS) study

The present study utilized transcranial magnetic stimulation (TMS) of the motor cortex to understand basic motor processes associated with depressive symptoms independent of cognitive requirements or diagnostic category. To assess the integrity of the basic cortical-spinal-motor circuit associated with depressed mood, TMS to the motor cortex was used to initiate motor evoked potentials (MEPs) in forearm EMG and force production measured in the right (dominant) index finger. While at rest, a group with more depressive symptoms showed less force response in the index finger following stimulations compared with a group endorsing less depressive symptoms. A negative correlation between force response in the index finger at baseline (rest) following stimulation and the Beck depression inventory indicated that depressive mood symptom elevations were associated with less response to stimulations. The results argue for a greater importance placed on the relationship between depressive mood symptoms and basic motor processes.     

Auditory Feedback and Conditioning of the Single Motor Unit

The effects of direct auditory feedback of the electromyogram (EMG) on learning to control a single motor unit (SMU) were investigated. Seventeen human subjects were injected with bipolar fine-wire electrodes into the tibialis anterior muscle. A trial light indicated the onset of a trial. If the subject activated an SMU, a correct light appeared. A non-SMU response was followed by an incorrect light. All subjects received an initial training series with auditory EMG feedback followed by a retest at 2 weeks without EMG feedback. Speed of initial learning was substantially improved by direct EMG feedback. The nature and amount of learning, including the ability to use proprioceptive cues in controlling an SMU, were not affected, nor was retention of learning.     

A Comparison of Auditory and Visual Feedback in Biofeedback Assisted Muscular Relaxation Training

This study compared the efficacy of auditory and visual feedback in electromyographic (EMG) biofeedback assisted relaxation training of the frontalis muscle.Twenty-eight subjects, divided into 4 groups matched on baseline frontalis EMG levels and trait anxiety, received 7 training sessions each under one of the following conditions: (1) auditory feedback-eyes closed; (2) auditory feedback-eyes open; (3) visual feedback; or (4) no feedback-eyes closed. The group who received auditory feedback with the eyes closed manifested significant lowering of EMG over session compared to no significant reduction in EMG for the other three groups. EMG changes failed to correlate significantly with changes in self reports of subjective relaxation derived from pre-to-post session state anxiety test data. The possibility that the ineffectiveness of visual feedback in this study may be specific to the frontalis muscle was discussed and the need for further research in several areas was stressed.     

Facilitatory effect on the motor cortex by electrical stimulation over the cerebellum in humans

Electrical stimulation over the cerebellum is known to transiently suppress the contralateral motor cortex in humans. However, projections from the cerebellar nuclei to the primary motor cortex are disynaptic excitatory pathways through the ventral thalamus. In the present investigation we studied facilitatory effects on the motor cortical excitability elicited by electrical stimulation over the cerebellum by recording surface electromyographic (EMG) responses from the first dorsal interosseous (FDI) muscle in nine normal volunteers. For primary motor cortical activation magnetic stimuli were given over the contralateral hand motor area with a figure-of-eight shaped coil with a current to preferentially elicit I3-waves (test stimulus). For cerebellar stimulation high-voltage electric stimuli were given with an anode on the ipsilateral mastoid process and a cathode over the contralateral process as previously described (conditioning stimulus). The effect of conditioning-test interstimulus intervals was investigated. Anodal cerebellar stimuli increased the size of EMG responses to magnetic cortical stimulation at an interstimulus interval of 3 ms. Reversing the current of conditioning stimulus abolished the facilitation. The same (anodal) conditioning stimuli did not affect electrically evoked cortical responses. Based on the effective polarity of the conditioning stimulus and the time course of facilitation we consider that this effect is due to motor cortical facilitation elicited by activation of the excitatory dentatothalamocortical pathway at the deep cerebellar nuclei or superior cerebellar peduncle. We conclude that the motor cortical facilitation is evoked by cerebellar stimulation in humans     

The origin of activity in the biceps brachii muscle during voluntary contractions of the contralateral elbow flexor muscles

During strong voluntary contractions, activity is not restricted to the target muscles. Other muscles, including contralateral muscles, often contract. We used transcranial magnetic stimulation (TMS) to analyse the origin of these unintended contralateral contractions (termed “associated” contractions). Subjects (n = 9) performed maximal voluntary contractions (MVCs) with their right elbow-flexor muscles followed by submaximal contractions with their left elbow flexors. Electromyographic activity (EMG) during the submaximal contractions was matched to the associated EMG in the left biceps brachii during the right MVC. During contractions, TMS was delivered to the motor cortex of the right or left hemisphere and excitatory motor evoked potentials (MEPs) and inhibitory (silent period) responses recorded from left biceps. Changes at a spinal level were investigated using cervicomedullary stimulation to activate corticospinal paths (n = 5). Stimulation of the right hemisphere produced silent periods of comparable duration in associated and voluntary contractions (218 vs 217 ms, respectively), whereas left hemisphere stimulation caused a depression of EMG but no EMG silence in either contraction. Despite matched EMG, MEPs elicited by right hemisphere stimulation were ∼1.5–2.5 times larger during associated compared to voluntary contractions (P < 0.005). Similar inhibition of the associated and matched voluntary activity during the silent period suggests that associated activity comes from the contralateral hemisphere and that motor areas in this (right) hemisphere are activated concomitantly with the motor areas in the left hemisphere. Comparison of the MEPs and subcortically evoked potentials implies that cortical excitability was greater in associated contractions than in the matched voluntary efforts.     

Cortical control of human soleus muscle during volitional and postural activities studied using focal magnetic stimulation

The surface-recorded electromyographic (EMG) responses evoked in the ankle musculature by focal, transcranial, magnetic stimulation of the motor cortex were studied in healthy human subjects. Such soleus evoked motor responses (EMRs) were characterised over a wide range of background levels of motor activity and using different stimulus intensities. EMRs were recorded during predominantly (1) volitional and (2) postural tasks. In the former task subjects were seated and voluntarily produced prescribed levels of soleus activation by reference to a visual monitor of EMG. In the latter task subjects assumed standing postures without EMG feedback. Comparison of the EMRs of soleus, traditionally considered a slow anti-gravity extensor muscle, during these tasks was used to evaluate its cortical control in primarily volitional versus primarily postural activities. The form of soleus EMRs produced by single magnetic cortical stimuli comprised an initial (approx. 30 ms) increase and subsequent (approx. 50 ms) depression of EMG. Cortical stimulation could elicit substantial excitatory soleus EMG responses; for example, responses evoked by mild, magnetic stimuli (125% threshold for inducing a response in the relaxed muscle) as subjects exerted full voluntary plantarflexor effort averaged almost 20% of the maximum M-wave which could be elicited by an electrical stimulus to the posterior tibial nerve. Excitatory EMRs could be elicited in the voluntarily relaxed soleus muscle of the majority of subjects during sitting. The amplitude of soleus responses, induced by threshold stimuli for the relaxed state or approximately 125% threshold intensity, increased approximately linearly with background EMG over a wide range of volitional contraction levels. By contrast, there was no systematic change in the latency of excitatory soleus EMRs with increasing voluntary effort. The excitatory responses evoked in the voluntarily relaxed soleus of seated subjects by magnetic stimulation were regularly facilitated by incremental, voluntary contraction of the contralateral ankle extensors in a graded manner. However, such facilitation of responses was not observed when subjects voluntarily activated the muscle in which EMRs were elicited. The pattern of the responses elicited in soleus by magnetic stimulation during the postural task generally resembled that found during the volitional task. The amplitudes of excitatory soleus EMRs at a given stimulus intensity, obtained when subjects stood quietly, leaned forwards or stood on their toes to produce differing levels of ankle extensor contraction, increased with background EMG. Overall, the relationship between the size of cortically evoked soleus responses and the tonic level of motor activity, observed in individual subjects at matched stimulus intensities, did not consistently differ between postural and volitional tasks. The present results suggest that the motor cortex is potentially capable of exerting rapid regulation of the soleus muscle, and presumably other ankle extensors, not only when the muscle participates in volitional tasks but also when it is engaged in postural maintenance.     

时间相干电场的外周神经无损刺激

外周神经电刺激可用于运动康复和慢性神经痛治疗,但目前具有空间选择性的无损刺激仍是一个有待解决的问题。提出一种基于时间相干(TI)电场的外周神经选择性无损电刺激方法,对大鼠坐骨神经进行实验,在其大腿腹侧与背侧皮肤上以平行于神经的方向布置刺激电极,通过相干电场扫描,将TI刺激峰值定位到神经上进行选择性刺激。结果表明,该方法可以在预先不知道神经确切位置的情况下通过扫描得出将刺激电场作用到神经的最佳电参数,从而实现对神经的选择性无损刺激,而且在刺激作用点不变的前提下实现刺激强度的控制。在此基础上研究TI电场对大鼠坐骨神经的刺激阈值I_T,测量固定频差Δf=0.5 Hz(n=12),改变频率f=1～6 kHz与固定f=5 kHz(n=11),改变频差Δf=0.5～10 Hz下的I_T,并将其和等幅kHz电场(n=7)的I_T进行比较。结果表明,等幅kHz电场的I_T显著高于TI电场(P<0.05),而且不同频率f下的I_T也有显著性差异(P<0.05),而不同频差Δf下的I_T却没有显著性差异(P>0.05),说明TI电流对大鼠坐骨神经的I_T受f影响而不受Δf影响,且刺激阈值I_T与频率f成正比关系。     

Dynamic changes in corticospinal excitability during motor imagery

 We investigated temporal changes in the amplitudes of motor-evoked potentials (MEPs) induced by transcranial magnetic stimulation over the left motor cortex during motor imagery. Nine subjects were instructed to imagine repetitive wrist flexion and extension movements at 1 Hz, in which the flexion timing was cued by a tone signal. Electromyographs (EMGs) were recorded from the first dorsal interosseous, flexor carpi radialis and extensor carpi radialis muscles of the right hand, and magnetic stimulation was delivered at 0, 250, 500 and 750 ms after the auditory cue. On average, the evoked EMG responses were larger in the flexor muscle during the phase of imagined flexion than during extension, whilst the opposite was true for the extensor muscle. There were no consistent changes in the amplitudes of MEPs in the intrinsic hand muscle (first dorsal interosseous). The EMG remained relaxed in all muscles and did not show any significant temporal changes during the test. The H-reflex in the flexor muscle was obtained in four subjects. There was no change in its amplitude during motor imagery. These observations lead us to suggest that motor imagery can have dynamic effects on the excitability of motor cortex similar to those seen during actual motor performance. Received: 23 July 1998 / Accepted: 26 October 1998