降低功耗的高频磁刺激仪电路参数优化设计及仿真

针对重复经颅磁刺激仪功率消耗高的问题,我们通过建立电路模型,利用MATLAB平台进行仿真计算,研究了一种对放电的剩余能量进行有效回收的方法,并对磁刺激仪充放电及电能回收电路进行了设计,同时利用MCU实现了对电路充放电的智能控制.通过NI的Multisim平台对电能回收电路进行了仿真验证.仿真结果表明,本研究设计的电能回收电路,能使放电能量的回收率达到21%,从而降低了重复经颅磁刺激系统的功耗,提高了电能的利用效率.     

重复经颅磁刺激仪的优化设计

本文建立了RLC磁刺激仪模型 ,给出了模型参数计算方法。将磁刺激系统的性能指标分为三部分 :反映磁刺激仪输出性能的损耗能量 ;反映线圈输出性能的峰值磁能 ;反映线圈结构的几何变量。在给定磁刺激条件下 ,调整平面螺旋线圈的结构并计算出依赖于线圈结构参数的磁刺激仪和线圈输出性能值 ,从而 ,寻找最优的系统参数。优化结果表明 :线圈外半径和线的直径 (或截面面积 )是关键因素 ,选择合适的线圈外半径和线结构可以大大降低功耗 ,提高磁刺激频率 ,解决线圈发热问题     

微机式磁刺激系统的设计仿真与建模研究

磁刺激技术作为医学康复一种非侵入式的诊疗技术,是当前该领域国际范围的一项重要的研究课题.目前,所用的磁刺激仪存在两大问题:①磁线圈聚焦性较差;②系统能耗较大.刺激阈值所需要的能耗大,由此仪器产热并造成刺激有效性降低.本文在近几年磁刺激技术研究的基础上,运用计算机对磁刺激系统的重要模块进行了仿真,其中包括主电路与微机控制电路的仿真,并对磁刺激线圈磁场进行建模研究,为日后的研究和实践提供了有益的理论依据.     

经颅磁刺激线圈的磁聚焦优化设计

经颅磁刺激是利用变化磁场产生的感应电场作用于可兴奋人体脑组织的过程,磁聚焦性能是经颅磁刺激线圈设计的一项重要指标。根据磁刺激线圈感应电场理论,我们设计了半圆螺线管用于经颅磁刺激,计算了其载流线圈随刺激深度的感应电场分布,并与传统的经颅磁刺激8字形线圈作比较。结果表明,半圆螺旋管线圈既继承了8字形线圈感应电场的主瓣聚焦性强的优良特性,又摒弃了其相对较大的旁瓣对浅表非靶组织的兴奋刺激的不良影响,完全达到了磁聚焦优化设计的目的,也更利于磁刺激兴奋点的定位。     

重复经颅磁刺激治疗抑郁症的刺激参数的研究进展

重复经颅磁刺激是在经颅磁刺激基础上发展起来的新的神经电生理技术,它利用磁场作用于大脑皮质产生感应电流来改变皮质神经细胞的动作电位,从而影响脑内代谢和神经电活动。本文简单综述了重复经颅磁刺激治疗抑郁症的部分刺激参数。     

经颅磁刺激的多尺度建模仿真研究

经颅磁刺激是一种无创无痛的电磁刺激手段,被广泛应用于神经调控,在临床上对多种精神疾病和神经类疾病有明显的治疗效果。本文从电磁场建模仿真,细胞跨膜电位建模仿真,以及神经元响应建模仿真3个方面对经颅磁刺激多尺度建模仿真研究进行了详细的综述,并提出现阶段存在的问题以及对未来的展望。经颅磁刺激的多尺度建模仿真对磁刺激仪的设计开发具有指导意义,对磁刺激的导航系统提供重要的理论基础,有助于我们更好的理解电磁刺激的神经调控机制。     

脑磁刺激空间感应电场分布的数学模型与计算机仿真

本研究建立了脑神经磁刺激研究中较常用的八字线圈感应电场分布的半无界空间数学模型 ,应用数值积分和图形旋转与消隐技术建立了计算机仿真方法 ,据此分析了八字线圈感应电场空间分布的特性 ,为设计具有更好空间定位性和矢量选择性的脑神经磁刺激线圈提供了有效的仿真手段和研究方法。     

面向鸽子机器人的磁刺激线圈仿真设计及实验研究

为了探究将磁刺激技术应用于动物机器人运动控制的可行性,本文面向鸽子机器人,仿真分析线圈半径、匝数等因素对磁刺激强度、深度及聚焦性的影响,提出线圈设计方案。将线圈置于鸽子头部及腿部,磁刺激同时记录腿部肌电。结果发现,磁刺激时肌电明显增强。降低磁刺激系统输出频率,输出电流增大,肌电随之增强。与脑部磁刺激相比,刺激坐骨神经引起的肌电增强反应更为显著。这表明,磁刺激系统通过驱动该线圈可以有效地实现对脑及外周神经功能的调控。本研究为后续实用性线圈优化改进提供了理论及实验指导,为动物机器人磁刺激运动控制实施奠定了初步的理论和实验基础。     

神经形状对磁刺激兴奋点定位的影响

本文首先用一曲线函数表示平行于组织－空气界面下方ｘｙ平面内弯曲神经的形状，并定义弯曲神经任意一点的方向为该点切线方向，然后给出磁刺激弯曲神经时一个修正的激活函数。该激活函数由４个部分组成：感应电场沿ｘ、ｙ方向的分量Ｅｘ、Ｅｙ和各个分量沿ｘ方向的导数ｄＥｘ／ｄｘ、ｄＥＹ／ｄｘ，同时，激活函数还与神经的弯曲形状有关。三维计算机仿真结果表明激活函数负峰值点的位置在弯曲神经弯曲起始点附近，神经形状影响神经     

反复经颅磁刺激治疗对难治性抑郁症白质微结构整合水平的影响

目的:探讨反复经颅磁刺激治疗(rTMS)对难治性抑郁症白质微结构整合的影响及其与临床疗效的关系。方法:30例难治性抑郁症病人(男19,女11),25例性别、年龄、教育程度等匹配的正常人作为对照组。采用rTMS(15Hz)治疗4周,30例病人采取随机双盲的方法 17例病人进行真刺激治疗,13例进行假刺激治疗。治疗前后分别进行汉密尔顿抑郁量表(HAMD,17项)、贝克抑郁量表(BDI)评估,并进行全脑弥散张量成像扫描。使用基于像素的分析方法比较各向异性分数(FA)。结果:难治性抑郁症左侧额中回(x=-18 y=46 z=-14)白质FA值显著降低(经像素水平FWE校正,P<0.05,像素值>50)。经真刺激治疗后,该脑区降低的FA值显著增高,并且增高的FA值与抑郁症病人降低的BDI及HAMD分值呈正相关;而假刺激组未发现该脑区在治疗后FA值的增高。结论:反复经颅磁刺激可能通过提高左侧额中回白质微结构整合水平达到治疗难治性抑郁症的目的。     

Perturbation of visuospatial attention by high-frequency offline rTMS

The contribution of different cortical regions to visuospatial attention can be probed with the help of perturbation techniques, such as transcranial magnetic stimulation (TMS). Repetitive TMS (rTMS) has also been suggested as a tool for the therapy of brain injuries, by adjusting the neural excitability of injured or intact brain regions. Low- and high-frequency rTMS have been shown to result in subsequent (offline) reductions or increases of local cortical excitability, respectively. Previous studies demonstrated that low-frequency (1 Hz) rTMS of posterior parietal cortex (PPC) produced significantly reduced detection of stimuli in the visual hemifield contralateral to the stimulation site, as well as increased ipsilateral detection. We here explored the functional impact of high-frequency (20 Hz) rTMS with an attention task similar to that of a previous low-frequency study (Hilgetag et al. in Nat Neurosci 4:953–957, 2001). Normal healthy subjects (N = 14) received high-frequency rTMS (20 Hz, 10 min, 50% stimulator output) over right or left PPC (coordinate points P4 or P3). After stimulation of the right PPC, detection of single visual stimuli in the contralateral hemifield was significantly impaired. Generally, rTMS of right and left PPC produced mirror-symmetric trends in reduced contralateral detection. These effects were still present after post-TMS sham stimulation (more than 20 min after the end of active rTMS). The results suggest that attentional function can be perturbed by high-frequency rTMS as well as by low-frequency rTMS, despite potential differences in the underlying neural mechanisms. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

重复经颅磁刺激治疗抑郁症的疗效分析及相关机制

目的:探讨重复经颅磁刺激(rTMS)对抑郁症患者症状及血清中脑源性神经营养因子(BDNF)的影响,并进一步分析二者的关系。方法:连续入组在精神科病房首次住院的抑郁症患者64例,将其随机分为真刺激组和伪刺激组,伪刺激组仅给予盐酸帕罗西汀治疗,真刺激组在给予盐酸帕罗西汀治疗的基础上加以10HZ重复经颅刺激治疗,治疗前和治疗4周后用汉密尔顿抑郁量表(HAMD)评估真刺激组和伪刺激组的症状,并抽取患者静脉血测定血浆中BDNF的含量,运用SPSS 20.0对收集的数据进行统计分析。结果:1真刺激组和伪刺激组治疗前HAMD总分和血清BNDF含量无明显差异,年龄、性别以及服用盐酸帕罗西汀的剂量比较无明显差异(P0.05);2治疗4周后真刺激组和伪刺激组的HAMD分值较治疗前均明显降低(t=22.417,19.380;P0.001),血清BNDF含量较治疗前明显升高(t=-14.612,-12.445;P0.001);真刺激组HAMD的减分值和血浆BNDF的升高值均显著大于伪刺激组(t=2.652,2.268;P0.05);3真刺激组和伪刺激组的疗效分布有显著差异,真刺激组疗效显著高于伪刺激组(Z=-3.283,P=0.001);4HAMD的减分值和血浆BNDF的升高值呈显著正相关(r=0.494,P0.001),BDNF差值可以解释HAMD差值变异的23.2%。结论:高频重复经颅磁刺激治疗可以显著提高抑郁症患者的治疗效果,BDNF分泌被激活可能是经颅磁刺激治疗抑郁症有效的机制之一。     

High-frequency priming stimulation does not enhance the effect of low-frequency rTMS in the treatment of tinnitus

Based on its ability to reduce the excitability of the cortex locally, low-frequency repetitive transcranial magnetic stimulation (rTMS) has been investigated for the treatment of hyperexcitability disorders such as auditory hallucinations and tinnitus. Results are promising, but characterized by only moderate improvement and a high inter-individual variability. Experimental data from motor cortex stimulation in healthy subjects indicates that the depressant effect of low-frequency rTMS can be enhanced by high-frequency priming stimulation. Here we will investigate whether high-frequency priming also improves the therapeutic efficacy of low-frequency rTMS in a clinical application. 32 patients with chronic tinnitus were randomly assigned to either a standard protocol of low-frequency rTMS (110% motor threshold, 1 Hz, 2000 stimuli/day) or a stimulation protocol in which priming stimulation with 6 Hz (90% motor threshold, 960 stimuli) preceded low-frequency rTMS (110% motor threshold, 1 Hz, 1040 stimuli/day). Stimulation was applied over the left auditory cortex by using MRI-guided coil positioning. The treatment outcome was assessed with a standardized tinnitus questionnaire. There was no significant difference between the standard protocol and the protocol involving priming stimulation. Both stimulation protocols resulted in significant clinical improvement after 10 days of stimulation, as compared to baseline. Our data does not support an enhancing effect of higher frequency priming on low-frequency rTMS in the treatment of tinnitus. Clinical trial registration: Priming stimulation as an enhancement of low-frequency repetitive Transcranial Magnetic Stimulation (rTMS) for the treatment of tinnitus - .     

Reducing false memories by magnetic pulse stimulation

False memories are ubiquitous and often to our detriment. Yet, certain pathologies, including anterior temporal lobe dementia and autism, can lead to literal recall and thus greater resistance to false memories. This inspired us to reduce false memories by temporarily inhibiting the left anterior temporal lobe, using low frequency magnetic pulse stimulation. This site has been implicated in semantic memory and conceptual labelling. After active stimulation, participants in the sham/TMS group had 36% fewer false memories than they had with sham stimulation, and intact veridical memory. This is comparable to the improvement that people with autism and semantic dementia show over “normal” individuals. This finding suggests a potential method for reducing certain types of false memories.     

Electrical and magnetic repetitive transcranial stimulation of the primary motor cortex in healthy subjects

Repetitive transcranial magnetic stimulation (rTMS) delivered in short trains at 5 Hz frequency and suprathreshold intensity over the primary motor cortex (M1) in healthy subjects facilitates the motor-evoked potential (MEP) amplitude by increasing cortical excitability through mechanisms resembling short-term synaptic plasticity. In this study, to investigate whether rTES acts through similar mechanisms we compared the effects of rTMS and repetitive transcranial electrical stimulation (rTES) (10 stimuli-trains, 5 Hz frequency, suprathreshold intensity) delivered over the M1 on the MEP amplitude. Four healthy subjects were studied in two separate sessions in a relaxed condition. rTMS and anodal rTES were delivered in trains to the left M1 over the motor area for evoking a MEP in the right first dorsal interosseous muscle. Changes in MEP size and latency during the course of the rTMS and rTES trains were compared. The possible effects of muscle activation on MEP amplitude were evaluated, and the possible effects of cutaneous trigeminal fibre activation on corticospinal excitability were excluded in a control experiment testing the MEP amplitude before and after supraorbital nerve repetitive electrical stimulation. Repeated measures analysis of variance (ANOVA) showed that rTES and rTMS trains elicited similar amplitude first MEPs and a similar magnitude MEP amplitude facilitation during the trains. rTES elicited a first MEP with a shorter latency than rTMS, without significant changes during the course of the train of stimuli. The MEP elicited by single-pulse TES delivered during muscle contraction had a smaller amplitude than the last MEP in the rTES trains. Repetitive supraorbital nerve stimulation left the conditioned MEP unchanged. Our results suggest that 5 Hz-rTES delivered in short trains increases cortical excitability and does so by acting on the excitatory interneurones probably through mechanisms similar to those underlying the rTMS-induced MEP facilitation.     

Asymmetric responses to repetitive transcranial magnetic stimulation (rTMS) over the left and right primary motor cortex in a patient with lateralized progressive limb-kinetic apraxia

Repetitive transcranial magnetic stimulation (5 Hz-rTMS, 10 stimuli, 120% resting motor threshold intensity, RMT) produces in healthy subjects a progressive facilitation of motor-evoked potential (MEP) amplitude probably through a short-term enhancement of cortical excitatory interneurones. We had the opportunity to investigate the effect of 5 Hz-rTMS delivered over the right and left primary motor cortex (M1) in a patient with limb-kinetic apraxia of the left hand and fingers and reduced cerebral perfusion in the fronto-parietal cortex of the right hemisphere documented by single-photon emission computed tomography scans. Changes in the MEP size during the trains and the RMT were measured and compared between the hemispheres. 5 Hz-rTMS was also delivered in a group of healthy subjects over both hemispheres in order to compare changes in the MEP size from the right and left M1. In the patient, 5 Hz-rTMS delivered over the left hemisphere elicited normal MEPs that progressively increased in size during the trains whereas 5 Hz-rTMS delivered over the right affected hemisphere failed to facilitate the MEP size. RMT was similar in both hemispheres. In healthy subjects, 5 Hz-rTMS delivered over either hemisphere elicited a similar, significant MEP size facilitation. Despite the limitations of a single case, our findings suggest an altered response to 5 Hz-rTMS over the M1 of the affected hemisphere. This asymmetric response correlated with the altered perfusion in the right hemisphere and the patient's lateralized clinical manifestations of apraxia.     

Improvement of tactile perception and enhancement of cortical excitability through intermittent theta burst rTMS over human primary somatosensory cortex

Adopting the patterns of theta burst stimulation (TBS) used in brain-slice preparations, a novel and rapid method of conditioning the human brain has recently been introduced. Using short bursts of high-frequency (50 Hz) repetitive transcranial magnetic stimulation (rTMS) has been shown to induce lasting changes in brain physiology of the motor cortex. In the present study, we tested whether a few minutes of intermittent theta burst stimulation (iTBS) over left primary somatosensory cortex (SI) evokes excitability changes within the stimulated brain area and whether such changes are accompanied by changes in tactile discrimination behavior. As a measure of altered perception we assessed tactile discrimination thresholds on the right and left index fingers (d2) before and after iTBS. We found an improved discrimination performance on the right d2 that was present for at least 30 min after termination of iTBS. Similar improvements were found for the ring finger, while left d2 remained unaffected in all cases. As a control, iTBS over the tibialis anterior muscle representation within primary motor cortex had no effects on tactile discrimination. Recording somatosensory evoked potentials over left SI after median nerve stimulation revealed a reduction in paired-pulse inhibition after iTBS that was associated but not correlated with improved discrimination performance. No excitability changes could be found for SI contralateral to iTBS. Testing the performance of simple motor tasks revealed no alterations after iTBS was applied over left SI. Our results demonstrate that iTBS protocols resembling those used in slice preparations for the induction of long-term potentiation are also effective in driving lasting improvements of the perception of touch in human subjects together with an enhancement of cortical excitability. An erratum to this article can be found at