Rhythmic arm swing enhances long latency facilitatory effect of transcranial magnetic stimulation on soleus motoneuron pool excitability

The purpose of this study was to investigate whether rhythmic arm swing modulates the long latency effect of transcranial magnetic stimulation (TMS) on soleus motoneuron pool excitability. Ten healthy humans rhythmically swung the left arm back and forth in a sitting position. The soleus H-reflex was evoked when the arm was in the backward swing phase. Conditioning TMS was delivered over the motor cortex 8?ms before the soleus H-reflex was evoked. The soleus H-reflex amplitude in both legs was depressed by the rhythmic arm swing. In contrast, rhythmic arm swing enhanced the facilitatory effect of conditioning TMS over the motor cortex contralateral to the arm swing side on the soleus H-reflex ipsilateral to the arm swing side. This finding indicates that rhythmic arm swing enhances some polysynaptic facilitatory pathways from the motor cortex contralateral to the arm swing side to the soleus motoneuron pool ipsilateral to the arm swing side.     

A single dose of Ginkgo biloba does not affect soleus motoneuron pool excitability

EGb 761 has been shown to increase acetylcholine synthesis and release and increase cholinergic receptors leading to an increase in cholinergic neurotransmission. These effects may be observed in the neuromuscular system, manifested by changes in motoneuron pool excitability as measured by the Hoffmann reflex to motor response (H/M) ratio. The objective was to determine whether a single dose of EGb 761 affects motoneuron pool excitability of the soleus muscle as measured by the H/M ratio. Following initial soleus H/M measurements, 20 healthy volunteers were randomly assigned to 1 of 3 treatment groups (control, 180 g cellulose placebo, and 180 g EGb 761). H/M ratios were recorded 1, 2, and 3 hours post treatment. A 3 x 4 repeated-measures analysis of variance was used to analyze differences in H/M ratio between treatments. No differences were observed between treatments (p = 0.75) or over time (p = 0.17), and there was not a treatment by time interaction (p = 0.27). A single dose of 180 g of EGb 761 does not affect soleus motoneuron pool excitability.     

Effect of downhill running on motoneuron pool excitability.

The purpose of this study was to compare alterations in motoneuron pool excitability after eccentric-biased (ECC-B) downhill running exercise with non-biased (NO-B) level running exercise. Six male subjects (25-34 yr) participated in the study, which included ECC-B exercise (-10% grade) and NO-B exercise (0% grade) at 50% of maximal O2 uptake for 20 min. The control trial consisted of 20 min of quiet rest with all subjects participating in all conditions (repeated measures). Motoneuron pool excitability was measured by the Hoffman reflex (H-wave), which was expressed as a ratio (H/M ratio) of the maximal electrically stimulated muscle action potential (M-wave). NO-B exercise resulted in a 9.3 +/- 2.7% (SE) reduction in the H/M ratio. ECC-B exercise resulted in a 24.6 +/- 5.7% reduction in the ratio (P less than 0.05 for both). The two exercise treatment conditions were also significantly different from one another (P less than 0.05). Twenty-four-hour postexercise H/M ratios were similar to baseline (P greater than 0.05). Postexercise subjective muscle soreness assessment (DOMS) produced significant increases in DOMS of 36 and 166% immediately and 24 h after exercise, respectively, for the ECC-B trial only (P less than 0.001). The data show that ECC-B exercise results in greater postexercise H/M ratio reductions than NO-B exercise and that H/M ratio changes post-ECC-B exercise are not solely associated with DOMS.     

Effect of transcranial magnetic stimulation on treatment effect and immune function

To explore the effect of transcranial stimulation on the therapeutic effect and immune function of patients with post-stroke depression (PSD). Methods Selection in September 2020–April 2021 on the diagnosis of 70 patients with PSD as the research object, 35 patients were randomly divided into control group and intervention group and control group given conventional treatment, the intervention group in the control group on the basis of the application of transcranial magnetic stimulation treatment, compare the curative effect of two groups of patients after the treatment cycle and the effects on the immune function. Results After treatment, the levels of DA, NE, 5-HT in 2 groups were significantly increased, and those in the observation group were significantly higher than those in the control group (P < 0.05). After 8 weeks of treatment, serum Gly content in 2 groups was significantly increased and Glu content was significantly decreased compared with before treatment. Compared with the control group, serum Gly content in observation group was significantly increased and Glu content was significantly decreased after treatment (P < 0.05). After 8 weeks of treatment, the contents of IL-1β, IL-6 and TNF-α in serum of 2 groups were significantly decreased, compared with the control group, the contents of IL-1β, IL-6 and TNF-α in serum of observation group were significantly decreased (P < 0.05); Before treatment, there was no significant difference in PHQ-9 score and MBI score between the two groups (P > 0.05). After 8 weeks of treatment, PHQ-9 score and MBI score in the two groups were better than before treatment, and the observation group was better than the control group (P < 0.05). Conclusion Transcranial magnetic stimulation therapy can not only effectively promote the synthesis and release of monoamine neurotransmitters in patients with post-stroke depression, regulate the inhibitory/excitatory amino acid neurotransmitters, reduce inflammatory response, improve the clinical treatment effect and enhance the immune function of PSD patients, which has clinical application value.     

Threshold of the soleus muscle H-reflex is less sensitive to the change in excitability of the motoneuron pool during plantarflexion or dorsiflexion in humans

In the present study, we investigated whether weak (10% of maximal voluntary contraction) tonic dorsiflexion (DF) and plantarflexion (PF) affects the two conventional parameters used for evaluating the excitability of the soleus motoneuron (MN) pool, i.e. the ratio of the threshold of H-reflex to that of M-response (H_th:M_th) and the ratio of the maximal amplitude of H-reflex to that of M-response (H_max:M_max) in human subjects. The results showed that the H_max:M_max decreased during DF and increased during PF compared with that during rest, whereas no clear alteration was observed in H_th:M_th. These results are consistent with the scheme proposed by earlier workers, who have argued that neither inhibitory nor facilitatory effects of the conditioning stimulus apply to specific spinal reflex circuits occurring around the threshold of the test H-reflex. It is suggested, therefore, that the conventional use of the H_th:M_th ratio as a parameter reflecting the excitability of the MN pool should be reconsidered.     

Increased probability of repetitive spinal motoneuron activation by transcranial magnetic stimulation after muscle fatigue in healthy subjects

Triple stimulation technique (TST) has previously shown that transcranial magnetic stimulation (TMS) fails to activate a proportion of spinal motoneurons (MNs) during motor fatigue. The depression in size of the TST response, but no attenuation of the conventional motor-evoked potential, suggested increased probability of repetitive spinal MN activation during exercise, even if some MNs failed to discharge by the brain stimulus. Here we used a modified TST [quadruple stimulation (QuadS) and quintuple stimulation (QuintS)] to examine the influence of fatiguing exercise on second and third MN discharges after a single TMS in healthy subjects. This method allows an estimation of the percentage of double and triple discharging MNs. Following a sustained contraction of the abductor digiti minimi muscle at 50% maximal force maintained to exhaustion, the size of QuadS and QuintS responses increased markedly, reflecting that a greater proportion of spinal MNs was activated two or three times by the transcranial stimulus. The size of QuadS responses did not return to precontraction levels during 10-min observation time, indicating long-lasting increase in excitatory input to spinal MNs. In addition, the postexercise behavior of QuadS responses was related to the duration of the contraction, pointing to a correlation between repeated activation of MNs and the subject's ability to maintain force. In conclusion, the study confirmed that an increased fraction of spinal MNs fire more than once in response to TMS when the muscle is fatigued. Repetitive MN firing may provide an adaptive mechanism to maintain motor unit activation and task performance during sustained voluntary activity.     

The effect of repetitive transcranial magnetic stimulation on gamma oscillatory activity in schizophrenia

Background

Gamma (γ) oscillations (30–50 Hz) have been shown to be excessive in patients with schizophrenia (SCZ) during working memory (WM). WM is a cognitive process that involves the online maintenance and manipulation of information that is mediated largely by the dorsolateral prefrontal cortex (DLPFC). Repetitive transcranial magnetic stimulation (rTMS) represents a non-invasive method to stimulate the cortex that has been shown to enhance cognition and γ oscillatory activity during WM.

Methodology and Principal Findings

We examined the effect of 20 Hz rTMS over the DLPFC on γ oscillatory activity elicited during the N-back task in 24 patients with SCZ compared to 22 healthy subjects. Prior to rTMS, patients with SCZ elicited excessive γ oscillatory activity compared to healthy subjects across WM load. Active rTMS resulted in the reduction of frontal γ oscillatory activity in patients with SCZ, while potentiating activity in healthy subjects in the 3-back, the most difficult condition. Further, these effects on γ oscillatory activity were found to be specific to the frontal brain region and were absent in the parieto-occipital brain region.

Conclusions and Significance

We suggest that this opposing effect of rTMS on γ oscillatory activity in patients with SCZ versus healthy subjects may be related to homeostatic plasticity leading to differential effects of rTMS on γ oscillatory activity depending on baseline differences. These findings provide important insights into the neurophysiological mechanisms underlying WM deficits in SCZ and demonstrated that rTMS can modulate γ oscillatory activity that may be a possible avenue for cognitive potentiation in this disorder.     

The effect of arm swing on lower extremities in vertical jumping

Although it is known that an arm swing can enhance the performance in vertical jumping, the mechanisms through which this enhancement occurs are not yet clearly described. The purpose of this study was to examine how arm swing affects the lower extremity torque, power and work in vertical jumping and to gain an insight into the mechanisms that enable the arm swing to increase jump height. Five subjects maximally performed two types of vertical squat jumps with (SJA) and without (SJ) an arm swing from a force platform. All performances were videotaped with a high-speed video camera (200 Hz). The jump heights, joint torques, power and work were calculated by combining kinematic and kinetic data. It was confirmed that arm swing enhanced the jump height significantly (p<0.01). The work by the hip and by the ankle was significantly augmented by arm swing (p<0.05 and p<0.01, respectively). However, the work by the knee was significantly smaller in SJA (p<0.05). The total work by the three lower extremity joints (ankle, knee and hip) was significantly larger in SJA (p<0.05). The increase of the lower extremity work by the arm swing (31.4 J) was about twice as large as the work done by the shoulder and elbow in SJA (16.3 J). It was concluded that the increment of jump height resulted mainly from the increase of the lower extremity work, which is considered to have been brought about by the additional load on the lower extremity due to the arm swing.     

Effects of transcranial magnetic stimulation on oxidative stress in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) reproduces a multiple sclerosis (MS)-like experimental model. The main objective was to evaluate the effect of extremely low-frequency electromagnetic fields (EL-EMF) application, like a paradigm of transcranial magnetic stimulation (TMS) in the development of EAE. Rats were injected with a single dose of 150?μg of myelin oligodendrocyte glycoprotein (MOG, fragment 35–55) to produce experimental MS. To assess the effect of TMS application in EAE, the rats were treated with TMS (60?Hz and 0.7?mT) for 2?h in the morning, once a day, 5 days a week, during 3 weeks. TMS was applied to the head. The effect of TMS on EAE was evaluated as motor symptoms and, oxidative and cell damage. The data showed that MOG induced motor symptoms as tail paralysis and limb paresis/paralysis, oxidative stress and cell death similar to MS when compared with control animals. Importantly, TMS application attenuated motor symptoms, oxidative and cell damage, whereas it increased antioxidant system. Our findings suggest that: (i) MOG reproduces an experimental model of MS characterised by oxidative and cell damage; and (ii) TMS application decreases oxidative stress and cell death induced by MOG.     

Effect of voluntary facilitation on the diaphragmatic response to transcranial magnetic stimulation.

We assessed recruitment curves of the surface diaphragm motor-evoked potential (MEP) after transcranial magnetic stimulation during relaxation and at three different levels of facilitation (20, 40, and 60% of maximal inspiratory esophageal pressure) in 10 healthy subjects (six young and four elderly). MEP amplitude recruitment curves varied between individuals during relaxation and at each level of facilitation. Amplitude recruitment curves during relaxation were reproducible in individual subjects. Inspiratory maneuvers caused a decrease in motor threshold and latency and an increase in MEP amplitude, positively correlated to the intensity of facilitation. These changes were similar in young and elderly subjects. The best fit for MEP amplitude recruitment curves for each condition was obtained with a Boltzmann model. The performance of repeated submaximal inspiratory maneuvers did not affect the amplitude recruitment curves of the relaxed diaphragm. We conclude that the recruitment curve of the diaphragm with transcranial magnetic stimulation is repeatable and changes consistently with facilitation and will, therefore, be a robust experimental tool for the investigation of supraspinal pathways to the diaphragm.     

Effects of L-dopa and transcranial magnetic stimulation on behavioral reactions in kindled rats

In acute experiment in rats, the chronic epileptogenesis was reproduced in the form of pharmacological kindling induced via repeated picrotoxin administrations (1.0-1.2 mg/kg, intraperitoneally). A reduction of exploratory behavior was shown in the early period of kindling (24 h as of the moment of the last epileptogen administration). The marked alleviation of these disturbances was registered in two weeks from the moment of cessation of kindled irritations. L-DOPA (100 mg/kg, intraperitoneally) and transcranial magnetic stimulation (20 impulses with an induction at the height of their development of 1.5 TI) was followed by the net increasing exploratory, sexual and eating behavior. This is in favour of regarding the activation of dopaminergic system as a mechanism of action of transcranial magnetic stimulation upon kindling-induced behavioral deterioration.     

重复经颅磁刺激联合低剂量氟西汀对CUMS抑郁小鼠的影响*

目的:探讨重复经颅磁刺激(rTMS)联合低剂量氟西汀对慢性不可预知轻度压力(CUMS)抑郁小鼠的影响及其交互作用。方法:取42只雄性BALB/c小鼠随机分为正常对照组(Control,7只)和抑郁症模型组(Model,35只),Model组小鼠给予限制塑料管内、鼠笼倾斜、不筑巢、拥挤环境、明暗颠倒、白噪声等6种刺激,每种刺激随机且不同时出现2次,共刺激4周建立CUMS模型。随后35只Model组鼠随机分为CUMS组(8只)、氟西汀组(Fluoxetine,9只)、rTMS组(9只)和rTMS+Fluoxetine组(9只)。Fluoxetine组给予腹腔注射氟西汀5 mg/(kg·d),rTMS组给予10 Hz频率刺激,rTMS+Fluoxetine组给予腹腔注射氟西汀5 mg/(kg·d)和10 Hz频率刺激,Control和CUMS模型组给予相同体积生理盐水腹腔注射和伪刺激,各组均连续干预4周,随后进行行为学实验,最后运用析因设计方差分析方法分析Fluoxetine与rTMS的交互作用。结果:与Control组比,CUMS组小鼠强迫游泳实验中不动时间显著升高(P＜0.05),蔗糖实验中糖喜好程度、旷场实验中心运动次数和体重变化率均显著下降(P＜0.05)。与CUMS组比,rTMS组、Fluoxetine组和rTMS+Fluoxetine组抑郁症小鼠强迫游泳实验中不动时间显著降低(P＜0.01)、蔗糖实验中糖喜好程度和旷场实验中心运动次数显著升高(P＜0.05),其中rTMS+Fluoxetine组联合应用效果更显著(P＜0.05),但体重变化率仅rTMS+Fluoxetine组有变化(P＜0.05)。结论:重复经颅磁刺激和/或氟西汀均能不同程度的改善CUMS小鼠抑郁状态,其中联合应用的干预作用优于单独使用氟西汀或rTMS的效果,且有交互作用。     

Influence of transcranial magnetic stimulation on spike-wave discharges in a genetic model of absence epilepsy

Transcranial magnetic stimulation (TMS) impulses, (0.5 Hz, 3 impulses) were presented at threshold intensity to male WAG/Rij rats. One group received stimuli, which involved motor responses of hindlimbs, rats of the second group received sham stimulation. Electrocorticograms (ECoG) were recorded before and up to 2 hr from the moment of transcranial magnetic stimulation. It was established that such stimulation engendered a reduction of spike-wave discharge (SWD) bursts duration. This effect was most pronounced in 30 min from the moment of cessation of stimulation, when a decrease of 31.4% was noted in comparison with sham-stimulated control group. The number of bursts of spike-wave discharges was reduced, but did not reach significant difference when compared both with pre-stimulative base-line level and with sham-stimulated control rats. Bursts of spike-wave discharges restored up to pre-stimulative level in 90-150 minutes from the moment of cessation of transcranial stimulation. It can be concluded that transcranical magnetic stimulation possessed an ability to engender short-time suppression of bursts of spike-wave discharges in WAG/Rij rats.     

"Effect of transcranial magnetic stimulation to motor cortex on pain perception and nociceptive reflex"

"Noxious stimulation over the foot can evoke a nociceptive flexor reflex (NR) in the lower limb especially for tibialis anterior muscle (TA). Components of NR include the monosynaptic fast latency NRII, and the polysynaptic slow latency NRIII, supposedly a spinal segmental reflex influenced by the supraspinal control. Pain perception is quantified by visual analogous scale (VAS) and has been reported to be related to NRIII. Previous papers have reported the long lasting effect of transcranial magnetic stimulation (TMS), as well as TMS suppressing pain perception. The purpose of this study was to investigate the immediate and prolonged effect of a single-pulse TMS to suppress NR and pain. NRIII was provoked at right TA by a train of electrical stimulation on the right toe in 10 healthy subjects. TMS was delivered over the vertex area to evoke right anterior tibialis muscle activity. A sham TMS from different directions of the coil was performed on the next day. The NRIII amplitude and VAS were measured. As a result, the amplitude of NRIII was significantly decreased than the control 50 ms pre-stimulation (0.20 ± 0.13 mA vs . 0.65 ± 0.42 mV, P = 0.016), 100 ms pre-stimulation (0.10 ± 0.10 mA vs . 0.65 ± 0.42 mV, P = 0.001), 15 min post-stimulation (0.12 ± 0.09 mA vs . 0.65 ± 0.42 mV, P = 0.004), and 30 min post-stimulation (0.41 ± 0.21 mA vs . 0.65 ± 0.42 mV, P = 0.046). VAS was diminished compared with the control 50 ms pre-stimulation (3.3 ± 0.9 vs . 5.4 ± 1.3, P = 0.002), 100 ms pre-stimulation (2.6 ± 0.5 vs . 5.4 ± 1.3, P < 0.001) and 15 min post-stimulation (3.5 ± 0.9 vs . 5.4 ± 1.3, P = 0.046). The NRIII amplitude was well correlated with VAS in reduction during the TMS condition and 15 min after electrical stimulation (P < 0.001). The sham TMS did not suppress NRIII or VAS. In conclusion, our results indicate that NRIII and the nociception can be inhibited by one single pulse TMS and such an effect can last for a period of time."     

The effect of odour priming on long latency visual evoked potentials of matching and mismatching objects.

This study reports a cross-modal, olfactory/visual event related potential (ERP) using odours as olfactory primes. The results show a difference in the ERP waveform for the N400 waveform when a visual image does not match the priming odour. An N400 peak was produced for both the matched and mismatched conditions but the peaks were significantly more negative for the mismatched condition. By the use of non-food odours this study extends an earlier finding by Grigor, who, using the same ERP paradigm, obtained similar results for food odours and photographs of food.     

重复经颅磁刺激对创伤性颅脑损伤患者脑脊液中兴奋性氨基酸 含量的影响

目的:探讨重复经颅磁刺激(rTMS)对急性颅脑损伤患者脑脊液中兴奋性氨基酸(EAA)含量的影响。方法:30例创伤性颅脑损伤(TBI)病人按格拉斯哥昏迷评分分为轻型组(rTMS3)、中型组(rTMS2)、重型组(rTMS1),每组10例,各组病人分别随机分为rTMS对照亚组(A组)及治疗亚组(B组),每亚组5例。于TBI后第15天行腰椎穿刺采集脑脊液,采用高效液相色谱法测定脑脊液中谷氨酸(ASP)及门冬氨酸(GLU)含量。结果:脑脊液ASP和GLU水平随着脑损伤程度的加重而升高,各rTMS治疗组与相应各对照组的EAA相比,rTMS治疗组EAA的水平均低于相应对照组。结论:rTMS可通过降低TBI后脑脊液EAA水平发挥脑保护作用。脑脊液EAA的含量变化可作为TBI严重程度的生化指标。     

重复经颅磁刺激对创伤性颅脑损伤患者脑脊液中兴奋性氨基酸含量的影响

目的：探讨重复经颅磁刺激（rTMS）对急性颅脑损伤患者脑脊液中兴奋性氨基酸（EAA）含量的影响。方法：30例创伤性颅脑损伤（TBI）病人按格拉斯哥昏迷评分分为轻型组（rTMS3）、中型组（rTMS2）、重型组（rTMS1）,每组10例,各组病人分别随机分为rTMS对照亚组（A组）及治疗亚组（B组）,每亚组5例。于TBI后第15天行腰椎穿刺采集脑脊液,采用高效液相色谱法测定脑脊液中谷氨酸（ASP）及门冬氨酸（GLU）含量。结果：脑脊液ASP和GLU水平随着脑损伤程度的加重而升高,各rTMS治疗组与相应各对照组的EAA相比,rTMS治疗组EAA的水平均低于相应对照组。结论：rTMS可通过降低TBI后脑脊液EAA水平发挥脑保护作用。脑脊液EAA的含量变化可作为TBI严重程度的生化指标。