经颅电刺激安全性的动物试验研究

目的：探讨重复经颅电刺激（TES）对实验动物的安全性影响。方法：用70只健康SD大鼠随机分为正常对照组（NC组）和实验1～6组（TES1～6组），每组10只，对TES各组分别给予以不同刺激电压（500～1500V）及刺激次数（10次／天与50次／天），对各组大鼠的行为、脑组织光镜、电镜下病理形态学、神经元特异性稀醇化酶（NSE）含量进行观察。结果：TES的大鼠在不同的刺激电压及不同的连续刺激次数下，各组大鼠均未出现异常活动，无肢体强直、阵挛，无继发性脑出血及癫痫等发生，脑组织形态学包括大体观察，普通光镜及透射电镜检查等与NC组比较差异无显著意义，血清NSE含量与NC组比较，差异无显著意义（P〉0．05）。结论：TES至少是在本实验所取值的刺激电压和刺激次数范围内，是一种比较安全的检查和治疗手段。     

经颅磁、电刺激运动诱发电位的安全性研究

经颅磁、电刺激运动诱发电位的安全性对比研究一直成为国内外有关学者所重视及争议的问题。本文作者通过动物实验及近数年的临床实践,采用上述两种运动诱发电位进行了动态观察及对比分析,认为如果按规定各参值进行临床检测并在选择病例中注意其适应症及禁忌症,则是安全的;但个别特殊病例则须结合机体状态进行分析后再行检测。     

经颅磁刺激电场分析研究进展

经颅磁刺激是一种利用通电线圈在脑部的诱发电场来调节皮质兴奋性的技术,广泛应用于神经病学、康复学等领域。经颅磁刺激诱发电场分析与安全性、刺激效果密切相关,在优化刺激方案、线圈设计方面具有重要意义,成为相关领域的研究重点。首先介绍经颅磁刺激3种常见的临床副作用,然后阐述经颅磁刺激现有研究中的常规电场分析方法,包括解析法和数值分析法及其应用场景,并讨论与电场分析密切相关的生物模型建模方法。此外,由于磁刺激线圈与组织中电场分布的密切相关性,介绍常规的刺激线圈结构类型,并结合磁刺激线圈的7种典型设计,分析基于有限元分析的球模型下的电场分布特征。最后,展望经颅磁刺激电场分析研究未来的发展趋势。     

经颅磁刺激治疗阿尔茨海默病研究进展

经颅磁刺激作为一种无创的神经刺激方法,因其具有相对安全、无创的特点而成为目前治疗阿尔茨海默病的研究热点。该文首先介绍了经颅磁刺激原理;然后分别介绍了经颅磁刺激对阿尔茨海默病整体认知功能及不同认知域的治疗效果;接着分别分析了不同参数对整体认知功能治疗效果的影响;最后总结了经颅磁刺激的治疗机制,并探讨了可能的治疗方案。     

经颅磁刺激技术在癫研究中的应用

经颅磁刺激技术在癫研究中的应用@王玉平!100053,北京$首都医科大学宣武医院癫中心经颅磁刺激;;癫~~     

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。     

经颅磁刺激技术在癫癎研究中的应用

1经颅磁刺激的原理和方法 根据法拉第电磁原理,电流流过线圈会使线圈产生磁场,该磁场会对在附近的另一个线圈内诱发出电流活动.     

不同重复经颅磁刺激模式对慢性精神分裂症阴性症状的疗效及安全性

目的：比较不同重复经颅磁刺激（ rTMS）模式对慢性精神分裂症阴性症状的疗效及安全性研究。方法：将90例慢性精神分裂症患者随机分为5Hz组、10Hz组、伪刺激组,每组30例。3组在维持原有抗精神病药物种类及剂量不变的基础上,刺激部位均选择左侧前额叶背外侧皮质区（ DLPFC）,刺激强度为80％运动阈值,每天1次,每周5次,共2周。治疗前后采用阳性与阴性症状量表（ PANSS）和阴性症状量表（ SANS）量表评定疗效。结果：3组治疗后比较,PANSS总分、阴性因子分、SANS评分差异有统计学意义（F＝22．99,39．73,31．90;P均＜0．05）,10Hz组较伪刺激组PANSS总分、阴性因子分、SANS评分低,差异有统计学意义（ q＝－5．60,－5．70,－7．67;P均＜0．05）;10Hz组较5Hz组PANSS总分、阴性因子分、SANS评分低,差异有统计学意义（ q＝－4．97,－5．80,－7．40;P均＜0．05）。与治疗前比较,10Hz组PANSS总分、阴性因子分、SANS评分降低,差异有统计学意义（ t＝－5．45,－7．03,－7．23;P均＜0．05）;5Hz组和伪刺激组PANSS总分及各因子分、SANS评分差异无统计学意义（P均＞0．05）。结论：10Hz rTMS模式能改善慢性精神分裂症患者阴性症状,有较好的安全性。     

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。     

Treating anxious depression using repetitive transcranial magnetic stimulation

Background

A subset of patients given a clinical diagnosis of major depressive disorder (MDD) are described as having “anxious depression,” a presentation that, in some studies, has been an indicator of poor response to pharmacotherapy. The aim of this study was to determine if anxious depression is associated with attenuated response to repetitive transcranial magnetic stimulation (rTMS), an FDA-approved treatment for MDD.

Methods

Participants were 32 adult outpatients with treatment resistant MDD who were referred for rTMS. The Hamilton Rating Scale for Depression (HAMD) was administered to assess treatment response, and anxious depression was defined as a score of seven or above on the anxiety/somatization factor of the HAMD. A quarter of the sample met the anxious depression criterion at pretreatment.

Results

Both depression (total score) and anxiety symptoms improved from pre- to post-treatment with moderate to large treatment effects. Patients with and without anxious depression demonstrated similar rates of improvement in depression. Patients with versus without anxious depression demonstrated larger improvements in anxiety.

Limitations

The sample size was small, and assessments did not include structured diagnostic interview or independent measures of anxiety symptoms.

Conclusions

For the sample as a whole, there were significant improvements in both depression and anxiety. Anxious depression was not associated with attenuated treatment response to rTMS.     

Side effects of transcranial magnetic stimulation biased task performance in a cognitive neuroscience study

Summary: Transcranial magnetic stimulation (TMS) is increasingly used as a research tool for functional brain mapping in cognitive neuroscience. Despite being mostly tolerable, side effects of TMS could influence task performance in behavioural TMS studies. In order to test this issue, healthy subjects assessed the discomfort caused by the stimulation during a verbal working memory task. We investigated the relation between subjective disturbance and task performance. Subjects were stimulated during the delay period of a delayed-match-to-sample task above cortical areas that had been identified before to be involved in working memory. Task performance and subjective disturbance due to side effects were monitored. The subjects’ grade of discomfort correlated with the error rates: the higher the discomfort, the more errors were made. Conclusively, TMS side effects may bias task performance in cognitive neuroscience studies and may thereby lead to misinterpretation of results. We emphasize the importance of controlling side effects of the stimulation as a source of biasing effects in TMS studies.     

Localising awareness of action with transcranial magnetic stimulation

 Seven subjects reacted to an auditory stimulus by pressing a response key and judged their reaction time (RT) by reporting the position of a rotating clock-hand at which they pressed the key. Transcranial magnetic stimulation (TMS) was delivered either over primary motor cortex (MI) or more anteriorly (with the centre of the coil over FCz) 75 ms before each subject’s median reaction time. TMS over MI produced substantial delays in actual RT, but much smaller delays in judged RT. TMS over FCz produced smaller delays in actual RT and relatively larger delays in judged RT. We conclude that awareness of responses is generated, at least in part, between premotor areas affected by stimulation over FCz and the primary motor cortex. Received: 3 June 1998 / Accepted: 4 February 1999     

Effect of apomorphine on cortical inhibition in Parkinson's disease patients: a transcranial magnetic stimulation study

In this study, transcranial magnetic stimulation (TMS) of the primary motor hand area was used to test cortical excitability in Parkinson's disease (PD) patients. Motor evoked potentials (MEPs) to TMS were studied at rest by utilising distinct paired-pulse TMS protocols. Out of 29 untreated PD patients and 29 healthy subjects, early cortical inhibition (1-6 ms) was studied in a first subgroup of 17 PD patients and 15 healthy subjects, whereas late cortical inhibition (20-200 ms) was studied in a second subgroup of 21 PD patients and 19 healthy subjects. In all PD patients the same TMS protocols were performed before and after 3 h of apomorphine infusion. In comparison to healthy subjects, untreated PD patients showed a significant reduction of both early and late cortical inhibition, which was maximal at 2-3 ms, and at 80-100 ms, respectively. Apomorphine administration consistently reversed all the MEP abnormalities found in PD patients. The lack of TMS effects on the Hoffman's reflex (HR), at those intervals revealing the reduced inhibition in PD patients, is compatible with a supraspinal origin of the observed MEP abnormalities. Our data suggest that the cortical and/or subcortical loss of dopaminergic transmission in PD patients is associated with impaired motor cortical inhibitory mechanisms, as tested by a decreased early and late MEP inhibition.     

经颅磁刺激对部位相关癫癎患者运动皮质功能的评估

目的:采用经颅磁刺激技术(TMS)探讨症状性运动部位相关癫癎患者发作间期运动皮质的兴奋性.方法:对诊断明确的34例癫癎患者(分治疗组和未治疗组)及20例年龄、性别匹配的正常对照组进行单脉冲经颅磁刺激,刺激部位头颅相应的运动手区和颈7棘突外侧,并于对侧小指外展肌记录运动诱发电位(MEP),分析其阈强度(TI)、周围潜伏期(PL)及皮质潜伏期(CL)、中枢传导时间(CCT)和静息期(SP).结果:所有癫癎患者PL、CL及CCT均在正常范围内,但TI和SP明显低于正常对照组(P< 0.01).在癫癎患者中,未治疗组TI及SP明显低于治疗组(P< 0.01),致癎灶侧TI及SP低于非致癎灶侧(P< 0.05),但非致癎灶侧SP亦缩短.结论:单脉冲低频TMS能有效地反映中枢运动皮质的功能状态,用于症状性运动部位相关癫癎患者发作间期运动皮质兴奋性研究具有重要的实用价值.     

Motor cortex excitability in Alzheimer's disease: a transcranial magnetic stimulation follow-up study

Transient cognitive and behavioral stabilization of patients with Alzheimer's disease (AD) is the main goal of acetylcholinesterase inhibitor (AChEI) therapy. Response to treatment is variable and it is usually assessed clinically via neuropsychological scales. Functional neuroimaging could ideally permit the objective evaluation of the topographic correlates of therapy on brain functioning, but is expensive and little available on a large scale. On the other hand, neurophysiological methods such as transcranial magnetic stimulation (TMS) could offer an alternative, low-cost and risk free tool of assessing response to treatment in AD. Previous TMS studies have demonstrated hyperexcitability and asymptomatic motor cortex reorganization in the early stages of AD in patients with normal motor function. The aim of this study was to compare motor cortex functionality in 10 AD patients before and after long-term AchEIs therapy in order to monitor potential drug-related changes in cortical excitability and organization. Examined parameters of motor cortex physiology were found to be unchanged in patients with stabilized cognitive performance during the therapy. TMS, along with clinical, neuropsychological, and neuroimaging data, could be an inexpensive measure of biological progression in AD and it might supplement traditional methods to assess the effects of therapy.     

Focal depression of cortical excitability induced by fatiguing muscle contraction: a transcranial magnetic stimulation study

Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the motor cortex were recorded in separate sessions to assess changes in motor cortex excitability after a fatiguing isometric maximal voluntary contraction (MVC) of the right ankle dorsal flexor muscles. Five healthy male subjects, aged 37.4±4.2 years (mean±SE), were seated in a chair equipped with a load cell to measure dorsiflexion force. TMS or TES was delivered over the scalp vertex before and after a fatiguing MVC, which was maintained until force decreased by 50%. MEPs were recorded by surface electrodes placed over quadriceps, hamstrings, tibialis anterior (TA), and soleus muscles bilaterally. M-waves were elicited from the exercised TA by supramaximal electrical stimulation of the peroneal nerve. H-reflex and MVC recovery after fatiguing, sustained MVC were also studied independently in additional sessions. TMS-induced MEPs were significantly reduced for 20 min following MVC, but only in the exercised TA muscle. Comparing TMS and TES mean MEP amplitudes, we found that, over the first 5 min following the fatiguing MVC, they were decreased by about 55% for each. M-wave responses were unchanged. H-reflex amplitude and MVC force recovered within the 1st min following the fatiguing MVC. When neuromuscular fatigue was induced by tetanic motor point stimulation of the TA, TMS-induced MEP amplitudes remained unchanged. These findings suggest that the observed decrease in MEP amplitude represents a focal reduction of cortical excitability following a fatiguing motor task and may be caused by intracortical and/or subcortical inhibitory mechanisms.     

Decreased susceptibility to pentylenetetrazol-induced seizures after low-frequency transcranial magnetic stimulation in rats

We studied the effects of low-frequency repetitive transcranial magnetic stimulation (rTMS) on seizure susceptibility in rats. rTMS of 1000 pulses at 0.5 Hz led to a prolonged latency for seizure development after an intraperitoneal injection of pentylenetetrazol. The rTMS effectively prevented the development of status epilepticus of pentylenetetrazol-induced convulsions. These findings indicate that low-frequency rTMS affects the neural excitability, in the direction of anticonvulsive, and therefore, suggest the possibility of therapeutic use of rTMS in epilepsy.     

Short-term reduction of intracortical inhibition in the human motor cortex induced by repetitive transcranial magnetic stimulation

Ten healthy subjects and two patients who had an electrode implanted into the cervical epidural space underwent repetitive transcranial magnetic stimulation (rTMS; 50 stimuli at 5 Hz at active motor threshold intensity) of the hand motor area. We evaluated intracortical inhibition before and after rTMS. In healthy subjects, we also evaluated threshold and amplitude of motor evoked potentials (MEPs), duration of cortical silent period and short-latency intracortical facilitation. rTMS led to a short-lasting reduction in the amount of intracortical inhibition in control subjects with a high interindividual variability. There was no significant effect on other measures of motor cortex excitability. Direct recordings of descending corticospinal volleys from the patients were consistent with the idea that the effect of rTMS on intracortical inhibition occurred at the cortical level. Since the level of intracortical inhibition can be influenced by drugs that act on GABAergic systems, this may mean that low-intensity repetitive magnetic stimulation at 5 Hz can selectively modify the excitability of GABAergic networks in the human motor cortex. Electronic Publication