共查询到20条相似文献，搜索用时 31 毫秒
1.
Casey S. Gilmore Patricia J. Dickmann Brent G. Nelson Greg J. Lamberty Kelvin O. Lim 《Brain stimulation》2018,11(2):302-309
Background
Impulsivity is a multidimensional personality trait observed across a variety of psychiatric disorders. Transcranial direct current stimulation (tDCS) applied over dorsolateral prefrontal cortex (DLPFC) has shown promise as an intervention to reduce impulsivity.Objective
To investigate the effects of tDCS paired with a decision-making task on risk-taking in Veterans with a clinical history of impulsive behavior.Methods
This was a randomized, single-blind, sham-controlled study. Participants performed the Balloon Analogue Risk Task (BART) while concurrently receiving either active or sham tDCS (right anodal/left cathodal over DLPFC) twice a day for five days. To evaluate generalization, the Risk Task was performed before and after the complete course of intervention. To evaluate durability, the BART and Risk Task were administered again at one and two month follow-up sessions.Results
Thirty Veterans participated: 15 received active tDCS and 15 received sham tDCS. For the trained BART task, individual growth curve analysis (IGC) examining individual variation of the growth rates over time showed no significant variations in individual trajectory changes over time (β = 0.02, p > 0.05). For the untrained Risk Task, IGC showed that the active tDCS group had a significant 46% decrease in risky choice from pre-to post-intervention, which persisted through the one and two month follow-up sessions. The sham tDCS group showed no significant change in risky choice from pre-to post-intervention.Conclusions
tDCS over DLPFC paired with a decision-making task effectively reduced risk-taking behavior in a group of Veterans with clinically-relevant impulsivity. Results suggest that this approach may be an effective neuroplasticity-based intervention for patients affected by impulsivity. 相似文献2.
L. Angius A.R. Mauger J. Hopker A. Pascual-Leone E. Santarnecchi S.M. Marcora 《Brain stimulation》2018,11(1):108-117
Background
Transcranial direct current stimulation (tDCS) has been used to enhance endurance performance but its precise mechanisms and effects remain unknown.Objective
To investigate the effect of bilateral tDCS on neuromuscular function and performance during a cycling time to task failure (TTF) test.Methods
Twelve participants in randomized order received a placebo tDCS (SHAM) or real tDCS with two cathodes (CATHODAL) or two anodes (ANODAL) over bilateral motor cortices and the opposite electrode pair over the ipsilateral shoulders. Each session lasted 10 min and current was set at 2 mA. Neuromuscular assessment was performed before and after tDCS and was followed by a cycling time to task failure (TTF) test. Heart rate (HR), ratings of perceived exertion (RPE), leg muscle pain (PAIN) and blood lactate accumulation (ΔB[La?]) in response to the cycling TTF test were measured.Results
Corticospinal excitability increased in the ANODAL condition (P < 0.001) while none of the other neuromuscular parameters showed any change. Neuromuscular parameters did not change in the SHAM and CATHODAL conditions. TTF was significantly longer in the ANODAL (P = 0.003) compared to CATHODAL and SHAM conditions (12.61 ± 4.65 min; 10.61 ± 4.34 min; 10.21 ± 3.47 min respectively), with significantly lower RPE and higher ΔB[La?] (P < 0.001). No differences between conditions were found for HR (P = 0.803) and PAIN during the cycling TTF test (P = 0.305).Conclusion
Our findings demonstrate that tDCS with the anode over both motor cortices using a bilateral extracephalic reference improves endurance performance. 相似文献3.
Background
There has been increased interest in the potential use of transcranial direct current stimulation (tDCS) as treatment for multiple conditions including depression, pain, and cognitive impairment. However, few studies account for the possible influence of comorbid medications when conducting tDCS research.Objective/Hypothesis
This literature review was conducted to examine what is currently known about the impact of medications on tDCS, provide recommendations for future research practices, and highlight areas where more research is needed.Methods
Key terms were searched in PubMed and Web of Science to identify studies that examine the impact of medication on tDCS effects in adults. Relevant papers' reference lists were also reviewed for thoroughness. Studies examined the effects of medication on 1 mA tDCS delivered to M1 (motor) and orbit/supraorbital (SO) area. All studies measured the effects of tDCS via MEP TMS paradigm.Results
Results of the literature review suggest multiple classes of medications, including sodium and calcium channel blockers, and medications that influence various neurotransmitter systems (GABA, dopamine, serotonin, etc.) may all impact tDCS effects on tissue excitability.Conclusions
Research to date suggests multiple classes of medications may impact tDCS effects. These results highlight the importance of documenting medication use in research subjects and carefully considering what types of medications should be allowed into tDCS trials. Many questions still remain regarding the exact mechanisms of action for tDCS and how various parameters (medication dosages, tDCS stimulation intensity, etc.) may further impact the effects of medications on tDCS. 相似文献4.
F. Fregni I.C. Macedo L.N. Spezia-Adachi V.L. Scarabelot G. Laste A. Souza Paulo Roberto Stefani Sanches W. Caumo I.L.S. Torres 《Brain stimulation》2018,11(2):299-301
Background
Chronic stress (CS) is associated with a decrease in pain threshold caused by the changes in neural pain circuits. It can be associated to glucocorticoid imbalance with alterations in neural circuitry. Inhibition of stress-induced pain-related neural changes by using techniques that safely induce neuroplasticity such as transcranial direct current stimulation (tDCS) may prevent hyperalgesia triggered by CS.Objective
This study aimed to verify the effect of tDCS performed prior to CS exposure on nociceptive response.Methods
Thirty-two rats were distributed in the following groups: control; stress; sham-tDCS + stress; and tDCS + stress. Bicephalic active tDCS was performed for 8 consecutive days before the CS exposure. The pain threshold was evaluated using a hot plate and tail flick latency (TFL) tests.Results
The tDCS exposure increased the pain threshold on stressed rats.Conclusion
The data obtained indicate that the treatment with bicephalic active tDCS before chronic stress exposure prevents stress-induced hyperalgesia. 相似文献5.
Colleen K. Loo Mustafa M. Husain William M. McDonald Scott Aaronson John P. O&#x;Reardon Angelo Alonzo Cynthia Shannon Weickert Donel M. Martin Shawn M. McClintock Adith Mohan Sarah H. Lisanby 《Brain stimulation》2018,11(1):125-133
Background
Evidence suggests that transcranial Direct Current Stimulation (tDCS) has antidepressant effects in unipolar depression, but there is limited information for patients with bipolar depression. Additionally, prior research suggests that brain derived neurotrophic factor (BDNF) Val66Met genotype may moderate response to tDCS.Objective
To examine tDCS efficacy in unipolar and bipolar depression and assess if BDNF genotype is associated with antidepressant response to tDCS.Methods
130 participants diagnosed with a major depressive episode were randomized to receive active (2.5 milliamps (mA), 30 min) or sham (0.034 mA and two 60-second current ramps up to 1 and 0.5 mA) tDCS to the left prefrontal cortex, administered in 20 sessions over 4 weeks, in a double-blinded, international multisite study. Mixed effects repeated measures analyses assessed change in mood and neuropsychological scores in participants with at least one post-baseline rating in the unipolar (N = 84) and bipolar (N = 36) samples.Results
Mood improved significantly over the 4-week treatment period in both unipolar (p = 0.001) and bipolar groups (p < 0.001). Among participants with unipolar depression, there were more remitters in the sham treatment group (p = 0.03). There was no difference between active and sham stimulation in the bipolar sample. BDNF genotype was unrelated to antidepressant outcome.Conclusions
Overall, this study found no antidepressant difference between active and sham stimulation for unipolar or bipolar depression. However, the possibility that the low current delivered in the sham tDCS condition was biologically active cannot be discounted. Moreover, BDNF genotype did not moderate antidepressant outcome.6.
Melanie K. Fleming John C. Rothwell Laszlo Sztriha James T. Teo Di J. Newham 《Clinical neurophysiology》2017,128(7):1389-1398
Objective
To assess the impact of electrode arrangement on the efficacy of tDCS in stroke survivors and determine whether changes in transcallosal inhibition (TCI) underlie improvements.Methods
24 stroke survivors (3–124 months post-stroke) with upper limb impairment participated. They received blinded tDCS during a motor sequence learning task, requiring the paretic arm to direct a cursor to illuminating targets on a monitor. Four tDCS conditions were studied (crossover); anodal to ipsilesional M1, cathodal to contralesional M1, bihemispheric, sham. The Jebsen Taylor hand function test (JTT) was assessed pre- and post-stimulation and TCI assessed as the ipsilateral silent period (iSP) duration using transcranial magnetic stimulation.Results
The time to react to target illumination reduced with learning of the movement sequence, irrespective of tDCS condition (p > 0.1). JTT performance improved after unilateral tDCS (anodal or cathodal) compared with sham (p < 0.05), but not after bihemispheric (p > 0.1). There was no effect of tDCS on change in iSP duration (p > 0.1).Conclusions
Unilateral tDCS is effective for improving JTT performance, but not motor sequence learning.Significance
This has implications for the design of future clinical trials. 相似文献7.
Objective
Chronic stroke patients with moderate-severe motor impairment may have an increased reliance on contralesional vs ipsilesional motor areas to control the paretic arm. We hypothesised that increasing contralesional excitability with anodal transcranial direct current stimulation (a-tDCS) would benefit motor performance in patients with moderate-severe impairment.Methods
Ten patients with motor impairment at the chronic stage after stroke received a-tDCS, cathodal (c-tDCS) and sham with the target electrode over contralesional motor cortex (M1). Motor performance was quantified from the circularity and size of planar movements made with the paretic arm. Contralateral and ipsilateral corticospinal excitability was inferred using transcranial magnetic stimulation. Corticospinal tract integrity and basal GABA concentration were assessed with magnetic resonance imaging and spectroscopy.Results
Anodal tDCS increased contralesional corticomotor excitability evident from motor evoked potentials in both wrist extensors (both P < 0.043). Cathodal tDCS did not affect corticomotor excitability (P > 0.37). The effect of tDCS on motor performance with the paretic limb was negatively associated with ipsilesional GABA concentration after c-tDCS (P = 0.001).Conclusions
Further investigation of noninvasive brain stimulation protocols that facilitate contralesional M1 is warranted.Significance
The inter-hemispheric imbalance model of stroke recovery may not apply to patients with more severe impairment. 相似文献8.
Background
High frequency transcranial random noise stimulation (hf-tRNS) facilitates performance in several perceptual and cognitive tasks, however, little is known about the underlying modulatory mechanisms.Objective
In this study we compared the effects of hf-tRNS to those of anodal and cathodal tDCS in a global motion direction discrimination task. An equivalent noise (EN) paradigm was used to assess how hf-tRNS modulates the mechanisms underlying local and global motion processing.Method
Motion coherence threshold and slope of the psychometric function were estimated using an 8AFC task in which observers had to discriminate the motion direction of a random dot kinematogram presented either in the left or right visual hemi-field. During the task hf-tRNS, anodal and cathodal tDCS were delivered over the left hMT+. In a subsequent experiment we implemented an EN paradigm in order to investigate the effects of hf-tRNS on the mechanisms involved in visual motion integration (i.e., internal noise and sampling).Results
hf-tRNS reduced the motion coherence threshold but did not affect the slope of the psychometric function, suggesting no modulation of stimulus discriminability. Anodal and cathodal tDCS did not produce any modulatory effects. EN analysis in the last experiment found that hf-tRNS modulates sampling but not internal noise, suggesting that hf-tRNS modulates the integration of local motion cues.Conclusion
hf-tRNS interacts with the output neurons tuned to directions near to the directional signal, incrementing the signal-to-noise ratio and the pooling of local motion cues and thus increasing the sensitivity for global moving stimuli. 相似文献9.
Pedro Caldana Gordon Christoph Zrenner Debora Desideri Paolo Belardinelli Brigitte Zrenner André Russowsky Brunoni Ulf Ziemann 《Brain stimulation》2018,11(5):1024-1032
Background
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique with potential for cost-effective therapeutic neuromodulation. Although positive therapeutic effects were found by stimulating the dorsolateral prefrontal cortex (DLPFC), few studies have investigated physiological effects of DLPFC-tDCS.Objectives
To investigate effects of tDCS with different parameter settings applied to the left DLPFC on cortical responses, measured by resting-state electroencephalography (rs-EEG) and transcranial magnetic stimulation (TMS)-evoked/induced EEG responses.Methods
22 healthy subjects underwent 5 tDCS sessions with different tDCS parameter settings in a double-blinded randomized crossover design (1: 1.5?mA, anode left-DLPFC, cathode right-DLPFC; 2: 1.5?mA, cathode left-DLPFC, anode right-DLPFC; 3: 0.5?mA, anode left-DLPFC, cathode right-DLPFC; 4: 1.5?mA, anode left-DLPFC, cathode left deltoid muscle; 5: sham stimulation). Rs-EEG and TMS-EEG were recorded before and after tDCS.Results
Rs-EEG power spectrum analysis showed no difference comparing baseline with post stimulation in any of the tDCS conditions. TMS-EEG evoked potential amplitude decreased in parietal cortex after 1.5?mA left-DLPFC anodal tDCS, and TMS-induced gamma and theta oscillations decreased after all conditions using left-DLPFC anodal tDCS. Left-DLPFC cathodal tDCS did not lead to significant change. None of the post-intervention changes was different when comparing the effects across conditions, including sham.Conclusions
Our study does not provide evidence that a single tDCS session results in significant changes in rs-EEG, using the current stimulation parameters. Significant changes in EEG responses to TMS pulses were observed following the anodal 1.5?mA tDCS interventions, although these changes were not statistically significant in a group comparison. 相似文献10.
Vishal Rawji Matteo Ciocca André Zacharia David Soares Dennis Truong Marom Bikson John Rothwell Sven Bestmann 《Brain stimulation》2018,11(2):289-298
Background
Measurements and models of current flow in the brain during transcranial Direct Current Stimulation (tDCS) indicate stimulation of regions in-between electrodes. Moreover, the folded cortex results in local fluctuations in current flow intensity and direction, and animal studies suggest current flow direction relative to cortical columns determines response to tDCS.Methods
Here we test this idea by using Transcranial Magnetic Stimulation Motor Evoked Potentials (TMS-MEP) to measure changes in corticospinal excitability following tDCS applied with electrodes aligned orthogonal (across) or parallel to M1 in the central sulcus.Results
Current flow models predicted that the orthogonal electrode montage produces consistently oriented current across the hand region of M1 that flows along cortical columns, while the parallel electrode montage produces non-uniform current directions across the M1 cortical surface. We find that orthogonal, but not parallel, orientated tDCS modulates TMS-MEPs. We also show modulation is sensitive to the orientation of the TMS coil (PA or AP), which is thought to select different afferent pathways to M1.Conclusions
Our results are consistent with tDCS producing directionally specific neuromodulation in brain regions in-between electrodes, but shows nuanced changes in excitability that are presumably current direction relative to column and axon pathway specific. We suggest that the direction of current flow through cortical target regions should be considered for targeting and dose-control of tDCS. 相似文献11.
Xinxin Guo Svante Östling Silke Kern Lena Johansson Ingmar Skoog 《Alzheimer's & dementia》2018,14(10):1253-1260
Introduction
Longitudinal studies are needed to understand the long-term associations between stroke and dementia.Methods
A population sample of 1460 women without stroke or dementia at baseline was followed over 44 years, from 1968 to 2012. Information on stroke and dementia was obtained from neuropsychiatric examinations, key-informant interviews, hospital registry, and medical records.Results
During 44 years follow-up, 362 women developed stroke and 325, dementia. The age-specific incidence of the two disorders was similar. The incidence of dementia was higher in those with stroke than among those without (33.7% vs. 18.5%; age-adjusted hazard ratio 1.44, 95% confidence interval 1.15–1.81). The increased risk of dementia started already 5 years before stroke, was highest 1 year after stroke, and continued more than 11 years after stroke.Discussion
There is an increased risk for dementia both before and after stroke. This has implications for understanding the relation between the two disorders and for prevention of dementia and stroke. 相似文献12.
Daniel G. da S. Machado Gozde Unal Suellen M. Andrade Alexandre Moreira Leandro R. Altimari André R. Brunoni Stéphane Perrey Alexis R. Mauger Marom Bikson Alexandre H. Okano 《Brain stimulation》2019,12(3):593-605
Background
Transcranial direct current stimulation (tDCS) has been used to improve exercise performance, though the protocols used, and results found are mixed.Objective
We aimed to analyze the effect of tDCS on improving exercise performance.Methods
A systematic search was performed on the following databases, until December 2017: PubMed/MEDLINE, Embase, Web of Science, SCOPUS, and SportDiscus. Full-text articles that used tDCS for exercise performance improvement in adults were included. We compared the effect of anodal (anode near nominal target) and cathodal (cathode near nominal target) tDCS to a sham/control condition on the outcome measure (performance in isometric, isokinetic or dynamic strength exercise and whole-body exercise).Results
22 studies (393 participants) were included in the qualitative synthesis and 11 studies (236 participants) in the meta-analysis. The primary motor cortex (M1) was the main nominal tDCS target (n?=?16; 72.5%). A significant effect favoring anodal tDCS (a-tDCS) applied before exercise over M1 was found on cycling time to exhaustion (mean difference?=?93.41?s; 95%CI?=?27.39?s–159.43?s) but this result was strongly influenced by one study (weight?=?84%), no effect was found for cathodal tDCS (c-tDCS). No significant effect was found for a-tDCS applied on M1 before or during exercise on isometric muscle strength of the upper or lower limbs. Studies regarding a-tDCS over M1 on isokinetic muscle strength presented mixed results. Individual results of studies using a-tDCS applied over the prefrontal and motor cortices either before or during dynamic muscle strength testing showed positive results, but performing meta-analysis was not possible.Conclusion
For the protocols tested, a-tDCS but not c-tDCS vs. sham over M1 improved exercise performance in cycling only. However, this result was driven by a single study, which when removed was no longer significant. Further well-controlled studies with larger sample sizes and broader exploration of the tDCS montages and doses are warranted. 相似文献13.
Cheyenne Allenby Mary Falcone Leah Bernardo E. Paul Wileyto Anthony Rostain J.Russell Ramsay Caryn Lerman James Loughead 《Brain stimulation》2018,11(5):974-981
Background
Impulsivity is a core deficit in attention deficit hyperactivity disorder (ADHD). Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits and could enhance DLPFC activity, leading to improved impulse control in ADHD.Objective
Hypothesis: We predicted 2.0?mA anodal stimulation (tDCS) versus sham stimulation applied over the left DLPFC would improve Conners Continuous Performance Task (CPT) scores. Our secondary hypothesis predicted that stop signal task (SST) reaction time (SSRT) would decrease with tDCS (versus sham).Methods
Thirty-seven participants completed two periods of three tDCS (or sham) sessions two weeks apart in a within-subject, double-blind, counterbalanced order. Participants performed a fractal N-back training task concurrent with tDCS (or sham) stimulation. Participants completed the CPT and SST at the beginning of treatment (baseline), at the end of the treatment, and at a 3-day post-stimulation follow-up.Results
There was a significant stimulation condition by session interaction for CPT false positive scores (χ2?=?15.44, p?<?0.001) driven by a decrease in false positive errors from baseline to end of treatment in the tDCS group (β?=??0.36, 95% Confidence Interval (CI) ?0.54 to ?0.18, p?<?0.001). This effect did not persist at follow-up (β?=??0.13, p?>?0.05). There was no significant stimulation condition by session interaction effect on CPT true positive errors or response time (ps?>?0.05). No significant change in SSRT performance was observed (p?>?0.05).Conclusion
These findings suggest that stimulation of the left DLPFC with tDCS can improve impulsivity symptoms in ADHD, supporting the therapeutic potential for tDCS in adult ADHD patients. 相似文献14.
Julius Fridriksson Jordan Elm Brielle C. Stark Alexandra Basilakos Chris Rorden Souvik Sen Mark S. George Michelle Gottfried Leonardo Bonilha 《Brain stimulation》2018,11(6):1276-1281
Background
Several studies, including a randomized controlled trial by our group, support applying anodal tDCS (A-tDCS) to the left hemisphere during behavioral aphasia treatment to improve outcomes. A clear mechanism explaining A-tDCS's efficacy has not been established, but modulation of neuroplasticity may be involved.Objective/hypothesis
The brain-derived neurotrophic factor (BDNF) gene influences neuroplasticity and may modulate the effects of tDCS. Utilizing data from our recently completed trial, we conducted a planned test of whether aphasia treatment outcome is influenced by interaction between A-tDCS and a single-nucleotide polymorphism of the BDNF gene, rs6265.Methods
Seventy-four individuals with chronic stroke-induced aphasia completed 15 language therapy sessions and were randomized to receive 1?mA A-tDCS or sham tDCS (S-tDCS) to the intact left temporoparietal region for the first 20?min of each session. BDNF genotype was available for 67 participants: 37 participants had the typical val/val genotype. The remaining 30 participants had atypical BDNF genotype (Met allele carriers). The primary outcome factor was improvement in object naming at 1 week after treatment completion. Maintenance of treatment effects was evaluated at 4 and 24 weeks.Results
An interaction was revealed between tDCS condition and genotype for treatment-related naming improvement (F?=?4.97, p?=?0.03). Participants with val/val genotype who received A-tDCS showed greater response to aphasia treatment than val/val participants who received S-tDCS, as well as the Met allele carriers, regardless of tDCS condition.Conclusion
Individuals with the val/val BDNF genotype are more likely to benefit from A-tDCS during aphasia treatment. 相似文献15.
Rick van der Vliet Zeb D. Jonker Suzanne C. Louwen Marco Heuvelman Linda de Vreede Gerard M. Ribbers Chris I. De Zeeuw Opher Donchin Ruud W. Selles Jos N. van der Geest Maarten A. Frens 《Brain stimulation》2018,11(4):759-771
Background
Cerebellar transcranial direct current stimulation has been reported to enhance motor associative learning and motor adaptation, holding promise for clinical application in patients with movement disorders. However, behavioral benefits from cerebellar tDCS have been inconsistent.Objective
Identifying determinants of treatment success is necessary. BDNF Val66Met is a candidate determinant, because the polymorphism is associated with motor skill learning and BDNF is thought to mediate tDCS effects.Methods
We undertook two cerebellar tDCS studies in subjects genotyped for BDNF Val66Met. Subjects performed an eyeblink conditioning task and received sham, anodal or cathodal tDCS (N?=?117, between-subjects design) or a vestibulo-ocular reflex adaptation task and received sham and anodal tDCS (N?=?51 subjects, within-subjects design). Performance was quantified as a learning parameter from 0 to 100%. We investigated (1) the distribution of the learning parameter with mixture modeling presented as the mean (M), standard deviation (S) and proportion (P) of the groups, and (2) the role of BDNF Val66Met and cerebellar tDCS using linear regression presented as the regression coefficients (B) and odds ratios (OR) with equally-tailed intervals (ETIs).Results
For the eyeblink conditioning task, we found distinct groups of learners (MLearner?=?67.2%; SLearner?=?14.7%; PLearner?=?61.6%) and non-learners (MNon-learner?=?14.2%; SNon-learner?=?8.0%; PNon-learner?=?38.4%). Carriers of the BDNF Val66Met polymorphism were more likely to be learners (OR?=?2.7 [1.2 6.2]). Within the group of learners, anodal tDCS supported eyeblink conditioning in BDNF Val66Met non-carriers (B?=?11.9% 95%ETI?=?[0.8 23.0]%), but not in carriers (B?=?1.0% 95%ETI?=?[-10.2 12.1]%). For the vestibulo-ocular reflex adaptation task, we found no effect of BDNF Val66Met (B?=??2.0% 95%ETI?=?[-8.7 4.7]%) or anodal tDCS in either carriers (B?=?3.4% 95%ETI?=?[-3.2 9.5]%) or non-carriers (B?=?0.6% 95%ETI?=?[-3.4 4.8]%). Finally, we performed additional saccade and visuomotor adaptation experiments (N?=?72) to investigate the general role of BDNF Val66Met in cerebellum-dependent learning and found no difference between carriers and non-carriers for both saccade (B?=?1.0% 95%ETI?=?[-8.6 10.6]%) and visuomotor adaptation (B?=?2.7% 95%ETI?=?[-2.5 7.9]%).Conclusions
The specific role for BDNF Val66Met in eyeblink conditioning, but not vestibulo-ocular reflex adaptation, saccade adaptation or visuomotor adaptation could be related to dominance of the role of simple spike suppression of cerebellar Purkinje cells with a high baseline firing frequency in eyeblink conditioning. Susceptibility of non-carriers to anodal tDCS in eyeblink conditioning might be explained by a relatively larger effect of tDCS-induced subthreshold depolarization in this group, which might increase the spontaneous firing frequency up to the level of that of the carriers. 相似文献16.
Pratik Y. Chhatbar Steven A. Kautz Istvan Takacs Nathan C. Rowland Gonzalo J. Revuelta Mark S. George Marom Bikson Wuwei Feng 《Brain stimulation》2018,11(4):727-733
Background
Transcranial direct current stimulation (tDCS) is a promising brain modulation technique for several disease conditions. With this technique, some portion of the current penetrates through the scalp to the cortex and modulates cortical excitability, but a recent human cadaver study questions the amount. This insufficient intracerebral penetration of currents may partially explain the inconsistent and mixed results in tDCS studies to date. Experimental validation of a transcranial alternating current stimulation-generated electric field (EF) in vivo has been performed on the cortical (using electrocorticography, ECoG, electrodes), subcortical (using stereo electroencephalography, SEEG, electrodes) and deeper thalamic/subthalamic levels (using DBS electrodes). However, tDCS-generated EF measurements have never been attempted.Objective
We aimed to demonstrate that tDCS generates biologically relevant EF as deep as the subthalamic level in vivo.Methods
Patients with movement disorders who have implanted deep brain stimulation (DBS) electrodes serve as a natural experimental model for thalamic/subthalamic recordings of tDCS-generated EF. We measured voltage changes from DBS electrodes and body resistance from tDCS electrodes in three subjects while applying direct current to the scalp at 2?mA and 4?mA over two tDCS montages.Results
Voltage changes at the level of deep nuclei changed proportionally with the level of applied current and varied with different tDCS montages.Conclusions
Our findings suggest that scalp-applied tDCS generates biologically relevant EF. Incorporation of these experimental results may improve finite element analysis (FEA)-based models. 相似文献17.
Background
Deeper short-interval intracortical inhibition (SICI), a marker of GABAA activity, correlates with better motor performance in patients with moderate to severe hand impairments in the chronic phase after stroke.Objectives
We evaluated the correlation between SICI in the affected hemisphere and pinch force of the paretic hand in well-recovered patients. We also investigated the correlation between SICI and pinch force in controls.Methods
Twenty-two subjects were included in the study. SICI was measured with a paired-pulse paradigm. The correlation between lateral pinch strength and SICI was assessed with Spearman's rho.Results
There was a significant correlation (rho?=?0.69, p?=?0.014) between SICI and pinch strength in patients, but not in controls. SICI was significantly deeper in patients with greater hand weakness.Conclusions
These preliminary findings suggest that decreased GABAA activity in M1AH correlates with better hand motor performance in well-recovered subjects with stroke in the chronic phase. 相似文献18.
Background
Transcranial direct current stimulation (tDCS) has been found to improve working memory (WM) performance in healthy participants following a single session. However, results are mixed and the overall effect size is small. Interpretation of these results is confounded by heterogeneous study designs, including differences in tDCS dose (current intensity) and sham conditions used.Aims
We systematically investigated the effect of tDCS dose on working memory using behavioural and neurophysiological outcomes.Methods
In a single-blind parallel group design, 100 participants were randomised across five groups to receive 15?min of bifrontal tDCS at different current intensities (2?mA, 1?mA, and three sham tDCS conditions at 0.034?mA, 0.016?mA, or 0?mA). EEG activity was acquired while participants performed a WM task prior to, during, and following tDCS. Response time, accuracy and an event-related EEG component (P3) were evaluated.Results
We found no significant differences in response time or performance accuracy between current intensities. The P3 amplitude was significantly lower in the 0?mA condition compared to the 0.034?mA, 1?mA and 2?mA tDCS conditions. Changes in WM accuracy were moderately correlated with changes in frontal P3 amplitude (channel Fz) following tDCS compared to baseline levels (r?=?0.34).Conclusions
Working memory was not significantly altered by tDCS, regardless of dose. The P3 amplitude showed that stimulation at 1?mA, 2?mA and a sham condition (0.034?mA) had biological effects, with the largest effect size for 1?mA stimulation. These findings indicate higher sensitivity of neurophysiological outcomes to tDCS and suggests that sham stimulation previously considered inactive may alter neuronal function. 相似文献19.
Joanna M. Wardlaw Stephen J. Makin Maria C. Valdés Hernández Paul A. Armitage Anna K. Heye Francesca M. Chappell Susana Muñoz-Maniega Eleni Sakka Kirsten Shuler Martin S. Dennis Michael J. Thrippleton 《Alzheimer's & dementia》2017,13(6):634-643
Introduction
Small vessel disease (SVD) is a common contributor to dementia. Subtle blood-brain barrier (BBB) leakage may be important in SVD-induced brain damage.Methods
We assessed imaging, clinical variables, and cognition in patients with mild (i.e., nondisabling) ischemic lacunar or cortical stroke. We analyzed BBB leakage, interstitial fluid, and white matter integrity using multimodal tissue-specific spatial analysis around white matter hyperintensities (WMH). We assessed predictors of 1 year cognition, recurrent stroke, and dependency.Results
In 201 patients, median age 67 (range 34–97), BBB leakage, and interstitial fluid were higher in WMH than normal-appearing white matter; leakage in normal-appearing white matter increased with proximity to WMH (P < .0001), with WMH severity (P = .033), age (P = .03), and hypertension (P < .0001). BBB leakage in WMH predicted declining cognition at 1 year.Discussion
BBB leakage increases in normal-appearing white matter with WMH and predicts worsening cognition. Interventions to reduce BBB leakage may prevent SVD-associated dementia. 相似文献20.
Elżbieta Kuźma Ilianna Lourida Sarah F. Moore Deborah A. Levine Obioha C. Ukoumunne David J. Llewellyn 《Alzheimer's & dementia》2018,14(11):1416-1426