1,721,300 research outputs found
Combining transcranial direct current stimulation and gravity-supported, computer-enhanced arm training in a chronic pediatric stroke survivor: a case report
No full textIntroduction: Transcranial direct current stimulation (tDCS) is a non-invasive method of brain stimulation that modulates cortical excitability via constant weak
electric currents.
Case presentation: We tested the feasibility and preliminary effects of combined tDCS with repetitive, task-specific practice of the affected upper extremity in a
19-year-old individual with no meaningful use of the right arm due to a chronic left middle cerebral artery infarction at the age of 12 years old. The subject underwent 10 training sessions over 2 weeks during which he received 40 minutes of tDCS while performing repetitive, multidirectional arm reaching and hand grasp/release activities in a gravity-supported, computer-enhanced environment. Potential side effects were investigated using the Digit Span test, the nine-item Patient Health Questionnaire, and the tDCS Adverse Effects Questionnaire. Clinical outcome measures were gathered pre-training, post-training and 2 weeks after the end of training. These measures included (i) the Jebsen-Taylor Hand Function Test, (ii) the Box and Block Test, (iii) the Fugl-Meyer Assessment for upper extremity, and
(iv) Motor Activity Log. In addition, during the training sessions, we collected kinematic measures during arm reaching. The subject tolerated the brain stimulation well. There were no effects on mood or working memory. Clinical outcome measures showed improvements in upper extremity motor function that were retained 2 weeks after completion of training. Movement kinematic parameters showed similar trends in response to training: improvements in mean speed, maximum speed, and acceleration of arm reaching movements.
Conclusions: Despite the fact that this case report does not detangle the effects of tDCS from motor training, it provides initial detailed clinical and kinematic data
showing beneficial effects of tDCS for enhancing motor recovery when combined with Gravity-Supported, Computer-Enhanced Arm Training that are useful for
future trials planning the use of this combined approach in pediatric stroke. We review the use of combined robotic-based arm training and tDCS for motor recovery in stroke
The potential dual role of transcallosal inhibition in post-stroke motor recovery
No full textUp to now, the mechanism of motor impairment and recovery after stroke has been thought to be based on the interhemispheric competition model. According to this model, which assumes that suppressing the excitability of contralesional hemisphere will enhance recovery by reducing transcallosal inhibition (TCI) of the stroke hemisphere, many clinical trials used non-invasive brain stimulation to improve motor function. Despite some positive findings, meta-analysis shows an important source of variability in the results, questioning whether the interhemispheric competition model would be exhaustive enough to explain the positive results or whether other mechanisms could explain the motor effects of inhibitory stimulation in the contralesional hemisphere. The goal of this study was to review the relationship between increased TCI and motor impairment after stroke. A systematic review of clinical studies investigating TCI through transcranial magnetic stimulation (TMS) in stroke patients and the relationship of this metric with motor recovery was then performed. After a literary search in PubMed eleven articles were included. The potential role of several covariates was examined and discussed. Overall, the importance of TCI as a putative mechanism for stimulation of the contralesional hemisphere seems to depend on the baseline motor function. In other words, from evidence coming mostly from chronic patients, modulation of abnormal TCI seems to be useful for patients with good motor function and less important in patients with poor motor function. TCI seems to be negatively correlated with mirror movements of the paretic hand. It can be inferred that suppressing the activity of the contralesional hemisphere could be beneficial for patients with good residual motor function and strong TCI, but not for those with poor motor function and weak TCI. Baseline motor function and measure of TCI should be taken into account for stratification of patients in clinical trials and for the design of customized treatment
Using Biophysical Models to Understand the Effect of tDCS on Neurorehabilitation: Searching for Optimal Covariates to Enhance Poststroke Recovery
No full textStroke is a leading cause of worldwide disability, and up to 75% of survivors suffer from some degree of arm paresis. Recently, rehabilitation of stroke patients has focused on recovering motor skills by taking advantage of use-dependent neuroplasticity, where high-repetition of goal-oriented movement is at times combined with non-invasive brain stimulation, such as transcranial direct current stimulation (tDCS). Merging the two approaches is thought to provide outlasting clinical gains, by enhancing synaptic plasticity and motor relearning in the motor cortex primary area. However, this general approach has shown mixed results across the stroke population. In particular, stroke location has been found to correlate with the likelihood of success, which suggests that different patients might require different protocols. Understanding how motor rehabilitation and stimulation interact with ongoing neural dynamics is crucial to optimize rehabilitation strategies, but it requires theoretical and computational models to consider the multiple levels at which this complex phenomenon operate. In this work, we argue that biophysical models of cortical dynamics are uniquely suited to address this problem. Specifically, biophysical models can predict treatment efficacy by introducing explicit variables and dynamics for damaged connections, changes in neural excitability, neurotransmitters, neuromodulators, plasticity mechanisms, and repetitive movement, which together can represent brain state, effect of incoming stimulus, and movement-induced activity. In this work, we hypothesize that effects of tDCS depend on ongoing neural activity and that tDCS effects on plasticity may be also related to enhancing inhibitory processes. We propose a model design for each step of this complex system, and highlight strengths and limitations of the different modeling choices within our approach. Our theoretical framework proposes a change in paradigm, where biophysical models can contribute to the future design of novel protocols, in which combined tDCS and motor rehabilitation strategies are tailored to the ongoing dynamics that they interact with, by considering the known biophysical factors recruited by such protocols and their interaction.Version of Recor
A controlled clinical trial of direct current stimulation in patients with refractory epilepsy
No full textTreatment of depression with transcranial direct current stimulation (tDCS): A Review
No full textMajor Depression Disorder (MDD) is usually accompanied by alterations of cortical activity and excitability, especially in prefrontal areas. These are reflections of a dysfunction in a distributed cortico-subcortical, bihemispheric network. Therefore it is reasonable to hypothesize that altering this pathological state with techniques of brain stimulation may offer a therapeutic target. Besides repetitive transcranial magnetic stimulation, tonic stimulation with weak direct currents (tDCS) modulates cortical excitability for hours after the end of stimulation, thus, it is a promising non-invasive therapeutic option. Early studies from the 1960s suggested some efficacy of DC stimulation to reduce symptoms in depression, but mixed results and development of psychotropic drugs resulted in an early abandonment of this technique. in the last years tDCS protocols have been optimized. Application of the newly developed stimulation protocols in patients with major depression has shown promise in few pilot studies. Further studies are needed to identify the optimal parameters of stimulation and the clinical and patient characteristics that may condition response to tDCS. (C) 2009 Elsevier Inc. All rights reserved
Repeated sessions of noninvasive brain DC stimulation is associated with motor function improvement in stroke patients
No full textPurpose: Recent evidence has suggested that a simple technique of noninvasive brain stimulation - transcranial direct cur-rent stimulation (tDCS) - is associated with a significant motor function improvement in stroke patients. Methods: We tested the motor performance improvement in stroke patients following 4 weekly sessions of sham, anodal- and cathodal tDCS (experiment 1) and the effects of 5 consecutive daily sessions of cathodal tDCS (experiment 2). A blinded rater evaluated motor function using the Jebsen-Taylor Hand Function Test. Results: There was a significant main effect of stimulation condition (p = 0.009) in experiment 1. Furthermore there was a significant motor function improvement after either cathodal tDCS of the unaffected hemisphere (p = 0.016) or anodal tDCS of the affected hemisphere (p = 0.046) when compared to sham tDCS. There was no cumulative effect associated with weekly sessions of tDCS. however consecutive daily sessions of tDCS (experiment 2) were associated with a significant effect oil time (p < 0.0001) that lasted for 2 weeks after treatment. Conclusions. The findings Of Our study support previous research showing that tDCS is significantly associated with motor function improvement in stroke patients; and support that consecutive daily sessions of tDCS might increase its behavioral effects. Because the technique of tDCS is simple, safe and non-expensive; our findings support further research on the use of this technique for the rehabilitation of patients with stroke
Modulation of the desire for specific foods with transcranial direct current stimulation
No full textA controlled clinical trial of direct current stimulation in patients with refractory epilepsy
No full text
Cortical stimulation of the prefrontal cortex with transcranial direct current stimulation reduces cue-provoked smoking craving: A randomized, sham-controlled study
No full textObjective: Because neuroimaging studies have shown that cue-provoked smoking craving is associated with changes in the activity of the bilateral dorsolateral prefrontal cortex (DLPFC), we aimed to investigate whether a powerful technique of noninvasive brain stimulation, transcranial direct current stimulation (tDCS), reduces cue-provoked smoking craving as indexed by a visual analog scale. Method: We performed a randomized, sham-controlled crossover study in which 24 subjects received sham and active tDCS (anodal tDCS of the left and right DLPFC) in a randomized order. Craving was induced by cigarette manipulation and exposure to a smoking video. The study ran from January 2006 to October 2006. Results: Smoking craving was significantly increased after exposure to smoking-craving cues (p < .0001). Stimulation of both left and right DLPFC with active, but not sham, tDCS reduced craving significantly when comparing craving at baseline and after stimulation, without (p = .007) and with (p = .005) smoking-craving cues. There were no significant mood changes in any of the conditions of stimulation. Adverse events were mild and distributed equally across all treatment conditions. Conclusions: Our findings extend the results of a previous study on the use of brain stimulation to reduce craving, showing that cortical stimulation with tDCS is beneficial for reducing cue-provoked craving, and thus support the further exploration of this technique for smoking cessation.NHLBI NIH HHS [K30 HL04095
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