Effect of repetitive transcranial magnetic stimulation on rate of memory acquisition

Repetitive transcranial magnetic stimulation (rTMS) may temporarily accelerate knowledge acquisition by neural networks, possibly by promoting rapid Hebbian learning. The authors tested this hypothesis in 20 normal subjects by comparing the impact of 25 minutes of high-frequency left dorsolateral prefrontal rTMS with that of sham rTMS on subsequent knowledge acquisition in several procedural and declarative memory domains. No significant group effects, positive or negative, were noted for any memory acquisition test, but prefrontal rTMS did reduce motor evoked potential threshold.     

Effect of daily repetitive transcranial magnetic stimulation for treatment of tinnitus: comparison of different stimulus frequencies

We compared the effect of different frequencies of repetitive transcranial magnetic stimulation (rTMS) (1 Hz, 10 Hz, 25 Hz and sham (occipital, 1 Hz)), given daily over the left temporoparietal cortex for 2 weeks, on 66 patients with chronic tinnitus randomly divided into four treatment groups. Patients were assessed using the Tinnitus Handicap Inventory, self-ratings of symptoms and audiometric measures of residual inhibition before, immediately after 2 weeks' treatment and monthly thereafter for 4 consecutive months. RESULTS: There were no significant differences in basal measures between the four groups of patients. A two-factor ANOVA revealed a significant "rTMS" x "time" interaction for all measures. This was because real rTMS produced greater improvement than sham. However, there was no significant difference between the responses to different frequencies of rTMS. The response to rTMS depended on the duration of tinnitus: patients who had tinnitus for the longest period of time were the least likely to respond to treatment. CONCLUSION: Daily sessions of rTMS over the temporoparietal cortex may be a useful potential treatment for tinnitus.     

Effect of low-intensity 50-Hz magnetic fields on kindling acquisition and fully kindled seizures in rats

The possibility that chronic exposure to power-line frequency (50 Hz) magnetic fields (MFs) might affect the acquisition or characteristics of focal and generalized seizures in amygdala kindled rats was studied. Acute, short-lasting 50-Hz MF exposure of fully kindled rats at either 1 or 100 μT had no effect on afterdischarge threshold (ADT) or seizure parameters recorded at ADT. In the chronic experiments, rats with electrodes implanted in the basolateral amygdala were exposed to a 50-Hz, 100-μT (1 Gauss) MF or to a sham field condition before and after onset of daily electrical stimulations over the whole period of kindling development. The focal seizure threshold (ADT) was determined before and after kindling development in MF exposed and sham exposed rats. Pre-kindling ADT was significantly increased by MF exposure. Exposed rats needed about the same number of stimulations to kindle than sham exposed rats, but the cumulative afterdischarge duration to reach criterion (i.e., a stage 5 seizure) was significantly reduced in MF exposed animals. Post-kindling ADT was similar in the two groups, but MF exposed rats showed a significantly higher threshold for generalized seizures. The data indicate that chronic exposure of rats to a 50-Hz, 100-μT MF exerts weak inhibitory effects on some seizure parameters of the kindling model.     

In-session seizures during low-frequency repetitive transcranial magnetic stimulation in patients with epilepsy

Low-frequency repetitive transcranial magnetic stimulation (rTMS) is emerging as a therapeutic tool for patients with intractable epilepsy. Although seizures during treatment have been reported as adverse events in some patients, the nature and severity of seizures that may be provoked by low-frequency rTMS in patients with epilepsy have not been extensively studied. Accordingly, this article documents seizures in patients (n = 5) with intractable epilepsy and average seizure frequency greater than one per day who underwent 1-Hz rTMS for seizure suppression. We report three observations in the present case series: (1) in each instance the in-session seizure was typical in semiology to the patient’s habitual seizures, (2) the duration of each documented seizure was either the same as or shorter than the patients’ baseline seizures, and (3) the overall neurological outcome on follow-up was not affected by the in-session seizures. More data will be required for valid conclusions with respect to safety and tolerability of low-frequency rTMS in patients with epilepsy, but it is noteworthy from our perspective that seizures during rTMS in this series were similar to the patients’ habitual seizures, occurred in patients with epilepsy with baseline seizure frequency exceeding one per day, and did not correlate with a poor neurological outcome or with absence of clinical response to rTMS.     

Chronic repetitive transcranial magnetic stimulation increases hippocampal neurogenesis in rats

Aim: While the underlying therapeutic mechanisms of repetitive transcranial magnetic stimulation (rTMS) treatment for depression remain unclear, recent animal studies have suggested that hippocampal neurogenesis might be required for the effects of antidepressant treatments including antidepressant drugs and electroconvulsive therapy. The aim of this study was to examine chronic rTMS effects on hippocampal neurogenesis in rats. Methods: Using a 70‐mm figure‐of‐eight coil, the stimulating parameters were set to 25 Hz and 70% of the rTMS device's maximum power. For 14 consecutive days, bromodeoxyuridine (BrdU) and 1000 pulses of rTMS were administered daily. Cell proliferation in the dentate gyrus was examined with immunohistochemistry. Results: In the rTMS‐treated group, BrdU‐positive cells were significantly increased in the dentate gyrus. Conclusion: Our results suggest that hippocampal neurogenesis might be involved in the antidepressant effects of chronic rTMS.     

Effect of repetitive transcranial magnetic stimulation on forced swimming test

Repetitive transcranial magnetic stimulation (rTMS) and electroconvulsive shock (ECS) have been shown to affect mood in health and disease. Evidence to date has demonstrated an antidepressant potential for rTMS and electroconvulsive therapy (ECT). The present experiment, aimed at comparing the effects of ECS and rTMS in rats, employed one test used for screening of antidepressant activity: the forced swimming test (FST). In this study, the authors investigated whether chronic rTMS influenced active behavior in the rat FST, similar to ECS. Male Wistar rats received rTMS treatment daily, for 10 days as is commonly used for ECT treatment. Control rats received sham treatment by placing the stimulation coil in a perpendicular position to the rat's head. Passing a current through earclip electrodes for 1 s induced ECS. The control animals were treated identically, but current was not applied. The FST was carried out 24 h after the last rTMS or ECS. The immobility time in the FST was not significantly affected by rTMS and ECS for 1 day. The immobility time in the FST was significantly shortened at rTMS and ECS for 10 days. Chronic treatment with rTMS, similar to chronic treatment with ECS, decreased the immobility time in the FST. These results indicate that chronic treatment with rTMS might have antidepressant effect similar to chronic treatment with ECS.     

Effect of chronic and acute low-frequency repetitive transcranial magnetic stimulation on spatial memory in rats

Repetitive transcranial magnetic stimulation (rTMS) is a novel, non-invasive neurological and psychiatric tool. The low-frequency (1 Hz or less) rTMS is likely to play a particular role in its mechanism of action with different effects in comparison with high-frequency (>1 Hz) rTMS. There is limited information regarding the effect of low-frequency rTMS on spatial memory. In our study, each male Wistar rat was daily given 300 stimuli (1.0 T, 200 micros) at a rate of 0.5 Hz or sham stimulation. We investigated the effects of chronic and acute rTMS on reference/working memory process in Morris water maze test with the hypothesis that the effect would differ by chronic or acute condition. Chronic low-frequency rTMS impaired the retrieval of spatial short- and long-term spatial reference memory but not acquisition process and working memory, whereas acute low-frequency rTMS predominantly induced no deficits in acquisition or short-term spatial reference memory as well as working memory except for long-term reference memory. In summary, chronic 0.5 Hz rTMS disrupts spatial short- and long-term reference memory function, but acute rTMS differently affects reference memory. Chronic low-frequency rTMS may be used to modulate reference memory. Treatment protocols using low-frequency rTMS in neurological and psychiatric disorders need to take into account the potential effect of chronic low-frequency rTMS on memory and other cognitive functions.     

重复经颅磁刺激技术应用于精神分裂症患者烟草依赖的疗效分析

目的探讨重复经颅磁刺激(rTMS)技术对降低住院精神分裂症患者烟草依赖程度的有效性与安全性.方法采用随机、双盲对照研究,前瞻性连续纳入2018年10月至2019年5月武汉大学人民医院精神科封闭病区住院的男性精神分裂症合并吸烟患者82例,所有患者符合精神分裂症与烟草依赖诊断标准.按随机数字表将所有患者随机分为治疗组(41例)与对照组(41例),治疗组给予高频rTMS(10 Hz,110%运动阈值),刺激左侧前额叶背外侧皮质,5次/周,治疗4周,共观察8周;对照组接受rTMS伪刺激治疗.比较两组患者治疗前后的日均吸烟数、尼古丁依赖检验量表(FTND)、吸烟渴求量表(TCQ)及阳性与阴性症状量表(PANSS)评分,评价两组患者的疗效及精神状况;比较两组患者不良反应发生率,评价其安全性.结果治疗组41例患者脱落3例,对照组41例脱落5例.脱落原因:4例为提前出院,2例为不依从,2例为精神症状复发不适宜继续试验.最终入组患者治疗组38例,对照组36例.两组患者治疗前后日均吸烟量、FTND、TCQ自评量表评分差异均有统计学意义(交互效应F值分别为61.398、43.117、77.144,均P<0.01),治疗组治疗第2、4和8周日均吸烟量、FTND、TCQ自评量表评分均显著低于对照组[日均吸烟量治疗第2、4和8周:(20.37±4.82)、(16.71±4.05)、(17.21±4.07)支比(27.72±7.21)、(27.17±7.11)、(26.06±5.86)支;FTND评分治疗第2、4和8周:(5.53±1.13)、(4.21±1.02)、(4.34±0.84)分比(7.11±1.47)、(7.06±1.43)、(7.06±1.53)分;TCQ评分治疗第2、4和8周:(62.74±4.20)、(55.26±4.92)、(54.97±5.03)分比(68.14±6.57)、(66.94±6.01)、(66.31±5.87)分],差异均有统计学意义(均P<0.01).两组治疗4周后PANSS总分、分量表评分及前后评分差值差异均无统计学意义(均P>0.05).治疗组发生不良反应7例(18.4%),其中头痛4例,失眠2例,坐立不安1例;对照组4例(11.1%),其中恶心2例,失眠1例,坐立不安1例,两组不良反应总发生率比较,差异无统计学意义(χ^2=0.781,P>0.05).不良反应均未经过处理,患者自行缓解.结论高频rTMS治疗可以降低精神分裂症患者日吸烟量和对烟草渴求程度,且安全性较好.     

不同频率重复经颅磁刺激对急性脑梗死患者静脉溶栓治疗的影响

目的比较不同频率的重复经颅磁刺激(rTMS)对急性脑梗死患者静脉溶栓治疗的影响。方法 141例急性脑梗死患者随机分为假rTMS治疗组、rTMS 1 Hz组、rTMS 2 Hz组、rTMS 5 Hz组、rTMS 10 Hz组和溶栓对照组,均予以尿激酶溶栓治疗。rTMS 1~10 Hz各组依次分别在溶栓同时给予rTMS 1 Hz、2 Hz、5 Hz、10 Hz治疗,假rTMS治疗组予以假rTMS刺激。所有患者于治疗前及治疗后24 h时进行美国国立卫生研究院卒中量表(NIHSS)评分,观察并记录各组不良反应情况。结果各组治疗后NIHSS评分均较治疗前明显下降(均P<0.05)。治疗后rTMS 1~10 Hz各组NIHSS评分均较溶栓对照组明显下降,其中rTMS 5 Hz组NIHSS评分最低(均P<0.05)。rTMS 1~10 Hz各组有效率(64.0%、76.2%、81.8%、83.3%)均明显高于假rTMS治疗组(42.3%)和溶栓对照组(47.8%)(均P<0.05)。其中,rTMS 2 Hz组、rTMS 5 Hz组与rTMS 10 Hz组有效率均高于rTMS 1 Hz组(均P<0.05)。各组间不良反应的比...     

Electroencephalogram and repetitive transcranial magnetic stimulation

Scalp recordings of the electroencephalogram (EEG) have been used in association with repetitive transcranial magnetic stimulation (rTMS) investigations as a safety measure in monitoring ongoing EEG activity and as a neurophysiologic tool in examining the specific effects induced by the magnetic stimulus on the EEG or evoked potentials (EPs). Medline review on the use of EEG or EPs with rTMS reveals that this area has been largely unexplored. Limited available studies attest to the potential for studies combining EEG/EPs and rTMS to be useful in further elucidating the normal brain physiology. Herein, we report on our experience with continuous EEG sampling combined with rTMS in patients with major depression (n = 14), schizophrenia (n = 7), and obsessive-compulsive disorder (n = 5). Our data support the practice of using continuous EEG monitoring when the stimulation parameters fall outside established safety guidelines.     

重复经颅磁刺激对帕金森病患者双眼竞争平均切换时间的影响

目的 探讨对帕金森病病患者辅助运动区进行重复经颅磁刺激（rTMS）的感知觉变化。 方法 回顾性连续纳入2018 年4—10 月于安徽医科大学第一附属医院神经内科门诊就诊的12 例帕金 森病患者（6 例男性，6 例女性），采用rTMS 的持续性θ爆发式磁刺激序列，在导航下对辅助运动区进行 连续14 d 的rTMS 治疗，治疗前后分别测定患者未服药状态下的双眼竞争平均切换时间，并采用汉密尔 顿焦虑量表（HAMA）、汉密尔顿抑郁量表17 项（HAMD-17）、统一帕金森病评定量表中第Ⅲ部分运动症 状评定量表（UPDRS Ⅲ）进行评定。结果 受试者治疗前UPDRS Ⅲ评分为（29.25±12.02）分，治疗后评 分为（24.00±11.63）分明显低于治疗前，差异有统计学意义（t=2.644，P ＜ 0.05）。受试者治疗前HAMA、 HAMD-17 评分分别为（9.08±3.09）、（9.75±3.52）分，治疗后分别为（8.50±3.29）、（8.75±3.22）分，治疗前 后评分差异均无统计学意义（t值分别为1.074、1.225，均P＞ 0.05）。治疗前后受试者双眼竞争平均切换 时间为（5.50±1.47）、（4.06±1.21）s，治疗后的双眼竞争平均切换时间较治疗前明显缩短，差异有统计学 意义（t=3.743，P ＜ 0.05）。结论 rTMS 干预帕金森病患者辅助运动区可加快帕金森病患者双眼竞争的 切换，提高其感知觉水平。     

Side effects of repetitive transcranial magnetic stimulation

The side effects of repetitive transcranial magnetic stimulation are largely unexplored and the limits of safe exposure have not been determined except as regards the acute production of seizures. Although tissue damage is unlikely, however, cognitive and other adverse effects have been observed and the possibility of unintended long-term changes in brain function are theoretically possible.     

Transient suppression of seizures by repetitive transcranial magnetic stimulation in a case of Rasmussen's encephalitis

Repetitive transcranial magnetic stimulation (rTMS) has been applied with variable success to terminate the seizures of epilepsia partialis continua. The rationale for using this technique to suppress ongoing seizures is the capacity of rTMS to interrupt ongoing neuronal activity, and to produce a lasting decrease in cortical excitability with low-frequency (1 Hz) stimulation. We report a case of epilepsia partialis continua in a child with Rasmussen's encephalitis, in whom seizures were transiently suppressed by 1-Hz rTMS delivered in nine daily 30-minute sessions. In this case, total ictal time was significantly reduced during stimulation, but the daily baseline seizure rate remained unchanged. Notably, the detection and quantification of this short-lived improvement were enabled by recording EEG continuously during the rTMS session. Thus, we present this case to illustrate a potential utility of combined continuous EEG recording and rTMS in seizure treatment.     

Accidental seizure with repetitive transcranial magnetic stimulation

Accidental induction of convulsions by using repetitive transcranial magnetic stimulation (rTMS) has been reported to have occurred in 6 normal voluntary subjects, in 1 patient with depression and in 1 patient who had temporal lobe epilepsy, with secondary generalization. In addition, 3 other cases have been published relating its use with seizure induction and in 1 case, using 1-Hz stimulation. In this paper, we report a patient who was participating in a protocol for the use of rTMS in chronic pain, with stimulation in the motor cortex, who developed a generalized seizure in the fifth application. Intertrain interval was within safety guidelines, but the combination of 10 Hz for 10 seconds was excessive and must be considered the main cause for the episode. No further complication has been noted after she was withdrawn from the study protocol.     

Effect of left prefrontal repetitive transcranial magnetic stimulation on food craving.

BACKGROUND: Dysfunction of the prefrontal cortex is implicated in craving for drugs and food. This study explores the effect of prefrontal cortex stimulation on food craving. METHODS: In a randomized double-blind parallel group study, 28 women, who reported frequent cravings for food were exposed to foods that typically elicit strong cravings before and after a single session of real or sham 10-Hz repetitive transcranial magnetic stimulation to the left dorsolateral prefrontal cortex at an intensity of 110% individual motor threshold. RESULTS: Self-reported food craving during exposure to the experimental foods remained stable before and after real stimulation compared with sham stimulation in which cravings increased over the experimental session. Consumption of snack foods within a 5-min period after stimulation did not differ between groups. CONCLUSIONS: Prefrontal stimulation inhibits the development of craving. A longer period of observation is necessary to establish whether there is an effect on food consumption.     

Effect of repetitive transcranial magnetic stimulation on auditory function following acoustic trauma

Repetitive transcranial magnetic stimulation (rTMS) is one form of non-invasive brain stimulation and increasingly shows neuroprotection in multiple neurological disorders. However, the potential of rTMS for protective action on auditory function following acoustic trauma has not been investigated. Here, we examined effect of TMS on hearing conservation, neurons survival and brain-derived neurotrophin factor (BDNF) expression in the cochlea and auditory cortex following acoustic trauma in rats. Wistar rats were exposed to intense pure tone noise (10 kHz, 120 dB SPL for 2 h) followed by rTMS treatment or sham treatment (handling control) daily for 14 days. Auditory brainstem response revealed there was no significant difference in hearing threshold shifts between rTMS- and sham-treated rats, although rTMS-treated rats showed less neuron loss in the auditory cortex in comparison with sham rats. Additionally, acoustic trauma increased BDNF expression in the cochlea and auditory cortex, and this elevation could be attenuated by rTMS treatment. Our results suggest present regiment of rTMS does not protect hearing against acoustic trauma, but maybe have implications for tinnitus treatment.     

Sex differences in antidepressant-like effect of chronic repetitive transcranial magnetic stimulation in rats

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neurophysiological technique. Pre-clinical and clinical studies supported that rTMS might have antidepressant effects. However, whether antidepressant effect of chronic rTMS is gender-dependent is still unknown. In this study, male and female Wistar rats received 10-day rTMS (4 trains of 15 Hz; 200 stimuli/day; 1.0 T) or control condition, and then were subjected to the forced-swim test (FST). We found that female rats consistently showed higher activity levels than males in FST and revealed the significant effects of gender and rTMS as well as the interaction of gender and rTMS. The result suggested the antidepressant-like effects of chronic rTMS on behavioral components in FST are gender-dependent. The gender discrepancy related to rTMS should not be neglected in antidepressant treatment of rTMS.     

Left prefrontal repetitive transcranial magnetic stimulation in schizophrenia

In a double-blind, controlled study, we examined the therapeutic effects of high-frequency left prefrontal repetitive transcranial magnetic stimulation (rTMS) on schizophrenia symptoms. A total of 22 chronic hospitalized schizophrenia patients were randomly assigned to 2 weeks (10 sessions) of real or sham rTMS. rTMS was given with the following parameters: 20 trains of 5-second 10-Hz stimulation at 100 percent motor threshold, 30 seconds apart. Effects on positive and negative symptoms, self-reported symptoms, rough neuropsychological functioning, and hormones were assessed. Although there was a significant improvement in both groups in most of the symptom measures, no real differences were found between the groups. A decrease of more than 20 percent in the total PANSS score was found in 7 control subjects but only 1 subject from the real rTMS group. There was no change in hormone levels or neuropsychological functioning, measured by the MMSE, in either group. Left prefrontal rTMS (with the used parameters) seems to produce a significant nonspecific effect of the treatment procedure but no therapeutic effect in the most chronic and severely ill schizophrenia patients.