The impact of transcranial direct current stimulation (tDCS) combined with modified constraint-induced movement therapy (mCIMT) on upper limb function in chronic stroke: a double-blind randomized controlled trial

Purpose: This pilot double-blind sham-controlled randomized trial aimed to determine if the addition of anodal tDCS on the affected hemisphere or cathodal tDCS on unaffected hemisphere to modified constraint-induced movement therapy (mCIMT) would be superior to constraints therapy alone in improving upper limb function in chronic stroke patients. Methods: Twenty-one patients with chronic stroke were randomly assigned to receive 12 sessions of either (i) anodal, (ii) cathodal or (iii) sham tDCS combined with mCIMT. Fugl–Meyer assessment (FMA), motor activity log scale (MAL), and handgrip strength were analyzed before, immediately, and 1 month (follow-up) after the treatment. Minimal clinically important difference (mCID) was defined as an increase of ≥5.25 in the upper limb FMA. Results: An increase in the FMA scores between the baseline and post-intervention and follow-up for active tDCS group was observed, whereas no difference was observed in the sham group. At post-intervention and follow-up, when compared with the sham group, only the anodal tDCS group achieved an improvement in the FMA scores. ANOVA showed that all groups demonstrated similar improvement over time for MAL and handgrip strength. In the active tDCS groups, 7/7 (anodal tDCS) 5/7 (cathodal tDCS) of patients experienced mCID against 3/7 in the sham group. Conclusion: The results support the merit of association of mCIMT with brain stimulation to augment clinical gains in rehabilitation after stroke. However, the anodal tDCS seems to have greater impact than the cathodal tDCS in increasing the mCIMT effects on motor function of chronic stroke patients.

• Implications for Rehabilitation

• The association of mCIMT with brain stimulation improves clinical gains in rehabilitation after stroke.

• The improvement in motor recovery (assessed by Fugl–Meyer scale) was only observed after anodal tDCS.

• The modulation of damaged hemisphere demonstrated greater improvements than the modulation of unaffected hemispheres.

     

经颅直流电刺激同步吞咽任务对健康人吞咽皮质运动中枢的影响

目的探索经颅直流电刺激（tDCS）同步吞咽任务对吞咽运动中枢的神经电生理学影响。 方法采用自身对照,双盲设计。选取健康受试者20例,先后给予阳极tDCS(a-tDCS)、阴极tDCS(c-tDCS)和虚假tDCS（s-tDCS）三种刺激模式,以吞咽强投射区为靶半球进行干预,并同步完成用力吞咽任务。单脉冲经颅磁刺激分别刺激双侧吞咽皮质代表区,记录tDCS干预前以及干预后5、30、60和90min舌骨上肌群的运动诱发电位（MEP）;采用两因素重复测量的方差分析对数据进行统计学处理。 结果tDCS干预因素可影响双侧吞咽运动皮质的兴奋性［同侧,F(2,28)=241.2,P<0.01;对侧,F(1,20)=29.5,P<0.01］。时间因素和tDCS干预因素有交互作用［同侧,F(3,46)=25.4,P<0.01;对侧,F(4,53)=6.6,P<0.01］。其中s-tDCS对双侧兴奋性的影响差异无统计学意义［同侧,P=0.894;对侧,P=0.354］。与s-tDCS相比,a-tDCS提高了刺激同侧的兴奋性,而不是对侧［同侧,MEP均值差值为21%±2%,95%可信区间为15%～27%,P<0.01;对侧,MEP均值差值为1%±2%,95%可信区间为-3.4%～6.5%,P>0.05］。与s-tDCS相比,c-tDCS抑制同侧而增强对侧的皮质兴奋性［同侧,MEP均值差值为-21%±2%,95%可信区间为-18%～-42%,P<0.01;对侧,MEP均值差值为20%±3%,95%可信区间为12%～29%,P<0.01］。 结论tDCS同时结合吞咽任务对吞咽运动中枢的影响具有极性依赖性和刺激半球依赖性特征;a-tDCS可以提高同侧吞咽皮质运动区的兴奋性,而c-tDCS则在抑制同侧吞咽运动皮质同时兴奋对侧吞咽皮质区。     

tDCS modulates cortical nociceptive processing but has little to no impact on pain perception

Transcranial direct current stimulation (tDCS) effectively modulates cortical excitability. Several studies suggest clinical efficacy in chronic pain syndromes. However, little is known regarding its effects on cortical pain processing. In this double-blind, randomized, cross-over, sham controlled study, we examined the effects of anodal, cathodal, and sham stimulation of the left motor cortex in 16 healthy volunteers using functional imaging during an acute heat pain paradigm as well as pain thresholds, pain intensity ratings, and quantitative sensory testing. tDCS was applied at 1 mA for 15 minutes. Neither cathodal nor anodal tDCS significantly changed brain activation in response to nociceptive stimulation when compared with sham stimulation. However, contrasting the interaction of stimulation modes (anodal/cathodal) resulted in a significant decrease of activation in the hypothalamus, inferior parietal cortex, inferior parietal lobule, anterior insula, and precentral gyrus, contralateral to the stimulation site after anodal stimulation, which showed the opposite behavior after cathodal stimulation. Pain ratings and heat hyperalgesia showed only a subclinical pain reduction after anodal tDCS. Larger-scale clinical trials using higher tDCS intensities or longer durations are necessary to assess the neurophysiological effect and subsequently the therapeutic potential of tDCS.     

Transcranial direct current stimulation: electrode montage in stroke

Neurophysiological and computer modelling studies have shown that electrode montage is a critical parameter to determine the neuromodulatory effects of transcranial direct current stimulation (tDCS). We tested these results clinically by systematically investigating optimal tDCS electrode montage in stroke. Ten patients received in a counterbalanced and randomised order the following conditions of stimulation (i) anodal stimulation of affected M1 (primary motor cortex) and cathodal stimulation of unaffected M1 (‘bilateral tDCS’); (ii) anodal stimulation of affected M1 and cathodal stimulation of contralateral supraorbital area (‘anodal tDCS’); (iii) cathodal stimulation of unaffected M1 and anodal stimulation of contralateral supraorbital area (‘cathodal tDCS’); (iv) anodal stimulation of affected M1 and cathodal stimulation of contralateral deltoid muscle (‘extra-cephalic tDCS’) and (v) sham stimulation. We used the Jebsen–Taylor Test (JTT) as a widely accepted measure of upper limb function. Bilateral tDCS, anodal tDCS and cathodal tDCS were shown to be associated with significant improvements on the JTT. Placing the reference electrode in an extracephalic position and use of sham stimulation did not induce any significant effects. This small sham controlled cross-over clinical trial is important to provide additional data on the clinical effects of tDCS in stroke and for planning and designing future large tDCS trials in patients with stroke.     

Transcranial direct current stimulation: electrode montage in stroke

Neurophysiological and computer modelling studies have shown that electrode montage is a critical parameter to determine the neuromodulatory effects of transcranial direct current stimulation (tDCS). We tested these results clinically by systematically investigating optimal tDCS electrode montage in stroke. Ten patients received in a counterbalanced and randomised order the following conditions of stimulation (i) anodal stimulation of affected M1 (primary motor cortex) and cathodal stimulation of unaffected M1 ('bilateral tDCS'); (ii) anodal stimulation of affected M1 and cathodal stimulation of contralateral supraorbital area ('anodal tDCS'); (iii) cathodal stimulation of unaffected M1 and anodal stimulation of contralateral supraorbital area ('cathodal tDCS'); (iv) anodal stimulation of affected M1 and cathodal stimulation of contralateral deltoid muscle ('extra-cephalic tDCS') and (v) sham stimulation. We used the Jebsen-Taylor Test (JTT) as a widely accepted measure of upper limb function. Bilateral tDCS, anodal tDCS and cathodal tDCS were shown to be associated with significant improvements on the JTT. Placing the reference electrode in an extracephalic position and use of sham stimulation did not induce any significant effects. This small sham controlled cross-over clinical trial is important to provide additional data on the clinical effects of tDCS in stroke and for planning and designing future large tDCS trials in patients with stroke.     

Pergolide increases the efficacy of cathodal direct current stimulation to reduce the amplitude of laser-evoked potentials in humans

Transcranial direct current stimulation (tDCS) was recently reintroduced as a tool for inducing relatively long-lasting changes in cortical excitability in focal brain regions. Anodal stimulation over the primary motor cortex enhances cortical excitability, whereas cathodal stimulation decreases it. Prior studies have shown that enhancement of D2 receptor activity by pergolide consolidates tDCS-generated excitability diminution for up to 24 hours and that cathodal stimulation of the primary motor cortex diminishes experimentally induced pain sensation and reduces the N2-P2 amplitude of laser-evoked potentials immediately poststimulation. In the present study, we investigated the effect of pergolide and cathodal tDCS over the primary motor cortex on laser-evoked potentials and acute pain perception induced with a Tm:YAG laser in a double-blind, randomized, placebo-controlled, crossover study. The amplitude changes of laser-evoked potentials and subjective pain rating scores of 12 healthy subjects were analyzed prior to and following 15 minutes cathodal tDCS combined with pergolide or placebo intake at five different time points. Our results indicate that the amplitude of the N2 component was significantly reduced following cathodal tDCS for up to two hours. Additionally, pergolide prolonged the effect of the cathodal tDCS for up to 24 hours, and a significantly lowered pain sensation was observed for up to 40 minutes. Our study is a further step toward clinical application of cathodal tDCS over the primary motor cortex using pharmacological intervention to prolong the excitability-diminishing effect on pain perception for up to 24 hours poststimulation. Furthermore, it demonstrates the potential for repetitive daily stimulation therapy for pain patients.     

经颅直流电刺激结合功能性电刺激对脑卒中平台期患者上肢运动功能康复影响的研究

目的:将经颅直流电刺激(tDCS)和功能性电刺激(FES)结合,观察这种联合治疗干预方式对脑卒中平台期患者上肢功能的影响。方法:3例脑卒中后平台期偏瘫患者在4周基线期后接受4周的tDCS结合FES治疗干预。干预前后用Fugl-Meyer上肢运动功能评分(U-FMA)、表面肌电图(sEMG)、经颅磁刺激(TMS)进行评定。结果:干预后U-FMA分数较干预前提高。7个主动肌中有5个表面肌电激活性干预前后有明显变化。用TMS成对刺激方法评估受试者健侧大脑短潜伏期皮质内抑制与短潜伏期皮质内易化结果显示部分的干预前后变化。结论:tDCS结合FES治疗干预改善了受试者上肢的运动功能,该方案可能是针对脑卒中平台期患者的一种有前景的干预康复方案。     

Comparison of Neuroplastic Responses to Cathodal Transcranial Direct Current Stimulation and Continuous Theta Burst Stimulation in Subacute Stroke

Objective

To investigate the effects of cathodal transcranial direct current stimulation (tDCS) and continuous theta burst stimulation (cTBS) on neural network connectivity and motor recovery in individuals with subacute stroke.

Anodal Transcranial Direct Current Stimulation of the Motor Cortex Ameliorates Chronic Pain and Reduces Short Intracortical Inhibition

ContextConsecutive sessions of transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) may be a suitable therapy to treat chronic pain, as it can modulate neural activities in the stimulated and interconnected regions.ObjectivesThe present study investigated the analgesic effect of five consecutive days of anodal/sham tDCS using subjective (visual analog scale [VAS]) and objective (cortical excitability measured by transcranial magnetic stimulation [TMS]) measurements.MethodsPatients with therapy-resistant chronic pain syndromes (trigeminal neuralgia, poststroke pain syndrome, back pain, fibromyalgia) participated. As this clinical trial was an exploratory study, statistical analyses implemented exploratory methods. Twelve patients, who underwent both anodal and sham tDCS, were analyzed using a crossover design. An additional nine patients had only anodal or sham stimulation. tDCS was applied over the hand area of the M1 for 20 minutes, at 1 mA for five consecutive days, using a randomized, double-blind design. Pain was assessed daily using a VAS rating for one month before, during, and one month post-stimulation. M1 excitability was determined using paired-pulse TMS.ResultsAnodal tDCS led to a greater improvement in VAS ratings than sham tDCS, evident even three to four weeks post-treatment. Decreased intracortical inhibition was demonstrated after anodal stimulation, indicating changes in cortico-cortical excitability. No patient experienced severe adverse effects; seven patients suffered from light headache after anodal and six after sham stimulation.ConclusionResults confirm that five daily sessions of tDCS over the hand area of the M1 can produce long-lasting pain relief in patients with chronic pain.     

Transcranial direct current stimulation over somatosensory cortex decreases experimentally induced acute pain perception

OBJECTIVE: Multiple cortical areas including the primary somatosensory cortex are known to be involved in nociception. The aim of this study was to investigate the effect of transcranial direct current stimulation (tDCS) that modulates the cortical excitability painlessly and noninvasively, over somatosensory cortex on acute pain perception induced with a Tm:YAG laser. METHODS: Subjective pain rating scores and amplitude changes of the N1, N2, and P2 components of laser-evoked potentials of 10 healthy participants were analyzed before and after anodal, cathodal, and sham tDCS. RESULTS: Our results demonstrate that cathodal tDCS significantly diminished pain perception and the amplitude of the N2 component when the contralateral hand to the side of tDCS was laser-stimulated, whereas anodal and sham stimulation conditions had no significant effect. DISCUSSION: Our study highlights the antinociceptive effect of this technique and may contribute to the understanding of the mechanisms underlying pain relief. The pharmacologic prolongation of the excitability-diminishing after-effects would render the method applicable to different patient populations with chronic pain.     

Effects of transcranial direct current stimulation (tDCS) on human regional cerebral blood flow

Transcranial direct current stimulation (tDCS) can up- and down-regulate cortical excitability depending on current direction, however our abilities to measure brain-tissue effects of the stimulation and its after-effects have been limited so far. We used regional cerebral blood flow (rCBF), a surrogate measure of brain activity, to examine regional brain-tissue and brain-network effects during and after tDCS. We varied the polarity (anodal and cathodal) as well as the current strength (0.8 to 2.0mA) of the stimulation. Fourteen healthy subjects were randomized into receiving either anodal or cathodal stimulation (two subjects received both, one week apart) while undergoing Arterial Spin Labeling (ASL) in the MRI scanner with an alternating off-on sampling paradigm. The stimulating, MRI-compatible electrode was placed over the right motor region and the reference electrode over the contralateral supra-orbital region. SPM5 was used to process and extract the rCBF data using a 10mm spherical volume of interest (VOI) placed in the motor cortex directly underneath the stimulating scalp electrode. Anodal stimulation induced a large increase (17.1%) in rCBF during stimulation, which returned to baseline after the current was turned off, but exhibited an increase in rCBF again in the post-stimulation period. Cathodal stimulation induced a smaller increase (5.6%) during stimulation, a significant decrease compared to baseline (-6.5%) after cessation, and a continued decrease in the post-stimulation period. These changes in rCBF were all significant when compared to the pre-stimulation baseline or to a control region. Furthermore, for anodal stimulation, there was a significant correlation between current strength and the increase in rCBF in the on-period relative to the pre-stimulation baseline. The differential rCBF after-effects of anodal (increase in resting state rCBF) and cathodal (decrease in resting state rCBF) tDCS support findings of behavioral and cognitive after-effects after cathodal and anodal tDCS. We also show that tDCS not only modulates activity in the brain region directly underlying the stimulating electrode but also in a network of brain regions that are functionally related to the stimulated area. Our results indicate that ASL may be an excellent tool to investigate the effects of tDCS and its stimulation parameters on brain activity.     

Transcranial direct current stimulation over the primary motor cortex during fMRI

Measurements of motor evoked potentials (MEPs) have shown that anodal and cathodal transcranial direct current stimulations (tDCS) have facilitatory or inhibitory effects on corticospinal excitability in the stimulated area of the primary motor cortex (M1). Here, we investigated the online effects of short periods of anodal and cathodal tDCS on human brain activity of healthy subjects and associated hemodynamics by concurrent blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) at 3T. Using a block design, 20s periods of tDCS at 1 mA intensity over the left M1 altered with 20s periods without tDCS. In different fMRI runs, the effect of anodal or cathodal tDCS was assessed at rest or during finger tapping. A control experiment was also performed, in which the electrodes were placed over the left and right occipito-temporo-parietal junction. Neither anodal nor cathodal tDCS over the M1 for 20s stimulation duration induced a detectable BOLD signal change. However, in comparison to a voluntary finger tapping task without stimulation, anodal tDCS during finger tapping resulted in a decrease in the BOLD response in the supplementary motor area (SMA). Cathodal stimulation did not result in significant change in BOLD response in the SMA, however, a tendency toward decreased activity could be seen. In the control experiment neither cathodal nor anodal stimulation resulted in a significant change of BOLD signal during finger tapping in any brain area including SMA, PM, and M1. These findings demonstrate that the well-known polarity-dependent shifts in corticospinal excitability that have previously been demonstrated using measurements of MEPs after M1 stimulation are not paralleled by analogous changes in regional BOLD signal. This difference implies that the BOLD signal and measurements of MEPs probe diverse physiological mechanisms. The MEP amplitude reflects changes in transsynaptic excitability of large pyramidal neurons while the BOLD signal is a measure of net synaptic activity of all cortical neurons.     

Effects of transcranial direct current stimulation on pain perception and working memory

Previous studies have shown that non‐invasive stimulation of the dorsolateral prefrontal cortex (DLPFC) could modulate experimentally induced pain and working memory (WM) in healthy subjects. However, the two aspects have never been assessed concomitantly. The present study was set up to investigate the effects of transcranial direct current stimulation (tDCS) of the DLPFC on thermal pain and WM in the same population of healthy volunteers. In a randomized and balanced order of different sessions separated by 1 week, 20 min of 2 mA anodal, cathodal or sham tDCS were applied to the left or right DLPFC in two separate experiments. Twelve healthy volunteers were enrolled for each stimulated hemisphere. Warm and cold detection thresholds, heat and cold pain thresholds as well as heat pain tolerance thresholds were measured before, during and following tDCS. WM was assessed by a 2‐back task applied once during cortical stimulation. Anodal tDCS of the right DLPFC led to an increase of tolerance to heat pain. The 2‐back task revealed fewer outliers during cathodal tDCS of the left DLPFC. The present data show an involvement of the DLPFC in the processing of pain and WM. There was no correlation between these findings, suggesting that the analgesic effects of cortical stimulation are not associated with cognitive processing. However, this conclusion is difficult to affirm because of some limitations of the study regarding the parameters of stimulation or a ceiling effect of the 2‐back task for instance.     

Effect of application of transcranial direct current stimulation during task-related training on gait ability of patients with stroke

[Purpose] The objective of this study was to determine the effect of transcranial direct current stimulation (tDCS) during task-related training (TRT) on the gait ability of patients with chronic stroke. [Subjects and Methods] The participants were 24 patients who were diagnosed with hemiplegia due to stroke. Three groups were created: subjects who performed TRT for general exercise therapy (TRT), subjects who received sham tDCS during TRT for general exercise therapy (TST), and subjects who received tDCS during TRT for general exercise therapy (TT). [Results] The stance phase symmetry profile, the swing phase symmetry profile, and gait velocity all decreased significantly in the TT group compared with the TRT group. However, there was no significant difference in the step length symmetry profile among the groups. [Conclusion] A application of tDCS, that affects the excitatory regulation in the cortical motor area, is an effective rehabilitation method for gait improvement.Key words: Gait, Hemiplegia, Transcranial direct current stimulation     

Transcranial direct current stimulation as an adjunct to cognitive training for older adults with mild cognitive impairment: A randomized controlled trial

BackgroundCognitive training (CT) for individuals with mild cognitive impairment (MCI) may not be optimal for enhancing cognitive functioning. Coupling CT with transcranial direct current stimulation (tDCS) may maximize the strength of transmission across synaptic circuits in pathways that are stimulated by CT. The synergistic effects arising from this combination could be superior to those with administration of CT alone.ObjectivesTo investigate whether the receiving tDCS combined with CT is superior to CT alone on domain-specific and task-specific cognitive outcomes in older adults with MCI.MethodsThis double-blind, sham-controlled randomized trial included 67 older adults with MCI assigned to 3 groups: 1) tDCS combined with CT (tDCS + CT), 2) sham tDCS combined with CT (sham tDCS + CT) and 3) CT alone. Nine sessions of computerized CT were administered to the 3 groups for 3 weeks. In addition, tDCS and sham tDCS was delivered to the left dorsolateral prefrontal cortex to the tDCS + CT and sham tDCS + CT groups, respectively, simultaneously with CT. Standardized cognitive assessments were performed at baseline, post-intervention, and at 6-week follow-up. Participants’ performance in the CT tasks was rated every session.ResultsThe 3 groups showed improvements in global cognition and everyday memory (P < 0.017) after the intervention and at follow-up, with larger effect sizes in the tDCS + CT than other groups (d > 0.94) but with no significant differences between groups. Regarding CT outcomes, the groups showed significant differences in favour of the tDCS + CT group in decreasing the completion and reaction times of working memory and attention activities (P < 0.017).ConclusionstDCS combined with CT was not superior to sham tDCS with CT and CT alone in its effects on domain-specific cognitive outcomes, but it did provide comparatively larger effect sizes and improve the processing speed of task-specific outcomes.ClinicalTrials.govNCT03441152.     

老年人下肢多关节闭链动作神经肌肉功能与坐到站动作表现的关系

目的:探讨老年人坐到站动作表现与在下肢多关节闭链动作下肢肌力、反应性和协调性等神经肌肉功能的相关性。方法:53位老年人受试者参与本研究,平均年龄(71.4±7.0)岁。利用功能性蹲屈测试训练仪,在下肢闭链、多关节动作模式下测量下肢的肌力、反应性(反应时间、动作时间)和协调性(轨迹追踪)。5次坐到站测试(FTSTS)来评估受试者从坐到站动作表现。所得资料以描述性统计、Pearson相关分析、偏相关分析和分层回归分析等进行统计分析。结果:Pearson相关分析与控制年龄变量后偏相关分析结果均显示FTSST时间与肌力、反应时和动作时有显著相关(P<0.05),但协调性测试结果与FTSST时间之间无相关(P>0.05)。分层多元回归分析结果提示肌力、反应时和动作时等变量为FTSST时间的重要预测因素,可解释FTSST时间42.5%的变异量,其中下肢肌力是最重要的预测因素(R2=0.26)。结论:本研究结果初步显示下肢肌力和反应性是预测坐到站动作表现重要的神经肌肉因素。     

Prefrontal hemodynamic changes produced by anodal direct current stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that has been investigated for the treatment of many neurological or neuropsychiatric disorders. Its main effect is to modulate the cortical excitability depending on the polarity of the current applied. However, understanding the mechanisms by which these modulations are induced and persist is still an open question. A possible marker indicating a change in cortical activity is the subsequent variation in regional blood flow and metabolism. These variations can be effectively monitored using functional near-infrared spectroscopy (fNIRS), which offers a noninvasive and portable measure of regional blood oxygenation state in cortical tissue. We studied healthy volunteers at rest and evaluated the changes in cortical oxygenation related to tDCS using fNIRS. Subjects were tested after active stimulation (12 subjects) and sham stimulation (10 subjects). Electrodes were applied at two prefrontal locations; stimulation lasted 10 min and fNIRS data were then collected for 20 min. The anodal stimulation induced a significant increase in oxyhemoglobin (HbO₂) concentration compared to sham stimulation. Additionally, the effect of active 10-min tDCS was localized in time and lasted up to 8–10 min after the end of the stimulation. The cathodal stimulation manifested instead a negligible effect. The changes induced by tDCS on HbO₂, as captured by fNIRS, agreed with the results of previous studies. Taken together, these results help clarify the mechanisms underlying the regional alterations induced by tDCS and validate the use of fNIRS as a possible noninvasive method to monitor the neuromodulation effect of tDCS.     

Prefrontal direct current stimulation modulates resting EEG and event-related potentials in healthy subjects: a standardized low resolution tomography (sLORETA) study

Prefrontal transcranial direct current stimulation (tDCS) with the anode placed on the left dorsolateral prefrontal cortex (DLPFC) has been reported to enhance working memory in healthy subjects and to improve mood in major depression. However, its putative antidepressant, cognitive and behavior action is not well understood. Here, we evaluated the distribution of neuronal electrical activity changes after anodal tDCS of the left DLPFC and cathodal tDCS of the right supraorbital region using spectral power analysis and standardized low resolution tomography (sLORETA). Ten healthy subjects underwent real and sham tDCS on separate days in a double-blind, placebo-controlled cross-over trial. Anodal tDCS was applied for 20 min at 2 mA intensity over the left DLPFC, while the cathode was positioned over the contralateral supraorbital region. After tDCS, EEG was recorded during an eyes-closed resting state followed by a working memory (n-back) task. Statistical non-parametric mapping showed reduced left frontal delta activity in the real tDCS condition. Specifically, a significant reduction of mean current densities (sLORETA) for the delta band was detected in the left subgenual PFC, the anterior cingulate and in the left medial frontal gyrus. Moreover, the effect was strongest for the first 5 min (p<0.01). The following n-back task revealed a positive impact of prefrontal tDCS on error rate, accuracy and reaction time. This was accompanied by increased P2- and P3- event-related potentials (ERP) component-amplitudes for the 2-back condition at the electrode Fz. A source localization using sLORETA for the time window 250-450 ms showed enhanced activity in the left parahippocampal gyrus for the 2-back condition. These results suggest that anodal tDCS of the left DLPFC and/or cathodal tDCS of the contralateral supraorbital region may modulate regional electrical activity in the prefrontal and anterior cingulate cortex in addition to improving working memory performance.     

经颅直流电刺激的研究及应用

背景：经颅直流电刺激是一种非侵袭性的刺激脑方法,利用弱的电流经颅刺激目标区域引起脑兴奋性的改变。目的：回顾分析经颅直流电刺激的基本原理、刺激程序、优越性及不良作用及其在脑功能各个区域与脑卒中和脊髓神经系统疾病中的应用。方法：由第一作者检索1995/2011PubMed数据库及西文生物医学期刊文献数据库。检索词为＂tDCS,Transcranial Direct Current Stimulation,noninvasive brain stimulation,stroke;经颅直流电刺激,非侵袭性脑刺激＂。结果与结论：国外近十年的研究已经确立经颅直流电刺激应用于人类大脑皮质的有益效果,并基本确立了其刺激模式。阳极刺激具有兴奋大脑皮质的作用,阴极刺激降低大脑皮质的兴奋性。应用于脑卒中患者的临床研究显示阳极刺激和阴极刺激均有有益的作用,阳极刺激对脊髓损伤的患者也有有益的效果。经颅直流电刺激作为一种新的,无创的,有效的治疗方法被广泛应用于神经系统损伤患者的研究中,为这样患者的康复带来新的希望。     

Five-day course of paired associative stimulation fails to improve motor function in stroke patients

Background

Non-invasive brain stimulation has been studied as a therapeutic adjunct for upper-limb recovery in patients with stroke. One type of stimulation, paired associative stimulation (PAS), has effects on plasticity in both patients and healthy participants. Lasting several hours, these effects are reversible and topographically specific.