Posts Tagged Brain stimulation

[ARTICLE] Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants – Full Text

Transcranial direct current stimulation (tDCS) is a technique used to modify cognition by modulating underlying cortical excitability via weak electric current applied through the scalp. Although many studies have reported positive effects with tDCS, a number of recent studies highlight that tDCS effects can be small and difficult to reproduce. This is especially the case when attempting to modulate performance using single applications of tDCS in healthy participants. Possible reasons may be that optimal stimulation parameters have yet to be identified, and that individual variation in cortical activity and/or level of ability confound outcomes. To address these points, we carried out a series of experiments in which we attempted to modulate performance in fluency and working memory probe tasks using stimulation parameters which have been associated with positive outcomes: we targeted the left inferior frontal gyrus (LIFG) and compared performance when applying a 1.5 mA anodal current for 25 min and with sham stimulation. There is evidence that LIFG plays a role in these tasks and previous studies have found positive effects of stimulation. We also compared our experimental group (N = 19–20) with a control group receiving no stimulation (n = 24). More importantly, we also considered effects on subgroups subdivided according to memory span as well as to more direct measures of executive function abilities and motivational levels. We found no systematic effect of stimulation. Our findings are in line with a growing body of evidence that tDCS produces unreliable effects. We acknowledge that our findings speak to the conditions we investigated, and that alternative protocols (e.g., multiple sessions, clinical samples, and different stimulation polarities) may be more effective. We encourage further research to explore optimal conditions for tDCS efficacy, given the potential benefits that this technique poses for understanding and enhancing cognition.

Introduction

Transcranial direct current stimulation (or tDCS) is a non-invasive form of brain stimulation which is used to modulate cognitive performance by applying a weak electric current via electrodes placed on the scalp. Early studies measuring effects of tDCS on motor cortical excitability suggested that the applied current can cause directional changes in the resting membrane potentials underneath the electrodes—with predominant depolarization under the anode (known as anodal tDCS) vs. hyperpolarization under the cathode (cathodal tDCS; de Berker et al., 2013). It is widely assumed that effects on cortical excitability map on to cognitive effects, with anodal vs. cathodal tDCS improving vs. worsening the cognitive function of targeted brains regions. However, though widely assumed, this might not necessarily be the case. Current flows between the electrodes with complex effects that are poorly understood. Moreover, an important confounding factor modulating the impact of tDCS may be individual variation in cortical activity and/or level of ability (for reviews, see Miniussi et al., 2013Horvath et al., 2015Li et al., 2015Westwood and Romani, 2017Westwood et al., 2017). These are widely cited as explanations for a number of recent reports of negative, inconsistent, and/or small effects linked to single applications of tDCS especially in healthy participants (see Horvath et al., 2015Mancuso et al., 2016Westwood et al., 2017). Our study will contribute to clarify the scope of tDCS effects by considering tasks that tax executive selection abilities, mediated by the frontal lobes, and where positive, but inconsistent, effects have been reported before. We will consider effects on the whole participant group, but crucially also on subgroups subdivided according to (a) general performance and control abilities; (b) working memory span; and (c) motivation levels to see whether these variables affect tDCS outcomes.[…]

 

Continue —> Frontiers | Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants | Neuroscience

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[WEB SITE] Brain-Machine Interface Shows Potential for Hand Paralysis – Rehab Managment

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The use of a brain-machine interface shows potential for helping to restore function in stroke patients with hand paralysis, according to a study of healthy adults published in the Journal of Neuroscience.

According to the study, researchers note that the brain-machine interface, which is designed to combine brain stimulation with a robotic device that controls hand movement, increases the output of pathways connecting the brain and spinal cord.

Researchers Alireza Gharabaghi and colleagues asked participants to imagine opening their hand without actually making any movement while their hand was placed in a device that passively opened and closed their fingers as it received the necessary input from their brain activity. Stimulating the hand area of the motor cortex at the same time, but not after, the robotic device initiated hand movement increased the strength of the neural signal, most likely by harnessing the processing power of additional neurons in the corticospinal tract, explains a media release from the Society for Neuroscience.

However, the signal decreased when participants were not required to imagine moving their hand. Delivering brain stimulation and robotic motor feedback simultaneously during rehabilitation may therefore be beneficial for patients who have lost voluntary muscle control, the release continues.

[Source(s): Society for Neuroscience]

via Brain-Machine Interface Shows Potential for Hand Paralysis – Rehab Managment

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[Editorial] Motor Priming for Motor Recovery: Neural Mechanisms and Clinical Perspectives – Neurology

Editorial on the Research Topic

Motor Priming for Motor Recovery: Neural Mechanisms and Clinical Perspectives

The Oxford dictionary defines the term priming as “a substance that prepares something for use or action.” In this special issue, we define motor priming as a technique, experience, or activity targeting the motor cortex resulting in subsequent changes in motor behavior. Inadequate functional recovery after neural damage is a persisting burden for many, and this insufficiency highlights the need for new neurorehabilitation paradigms that facilitate the capacity of the brain to learn and recover. The concept of motor priming has gained importance in the last decade. Numerous motor priming paradigms have emerged to demonstrate success to improve functional recovery after injury. Some of the successful priming paradigms that have shown to alter motor behavior and are easily implementable in clinical practice include non-invasive brain stimulation, movement priming, motor imagery, and sensory priming. The full clinical impact of these priming paradigms has not yet been realized due to limited evidence regarding neural mechanisms, safety and effectiveness, dosage, individualization of parameters, identification of the appropriate therapies that need to be provided in combination with the priming technique, and the vital time window to maximize the effectiveness of priming. In this special issue, four manuscripts address critical questions that will enhance our understanding of motor priming paradigms and attempt to bridge the gap between neurophysiology and clinical implementation.

In their study, “Non-Invasive Brain Stimulation to Enhance Upper Limb Motor Practice Poststroke: A Model for Selection of Cortical Site,” Harris-Love and Harrington elegantly address the extremely important issue of individualizing brain stimulation for upper limb stroke recovery. Many brain stimulation techniques show high interindividual variability and low reliability as the “one-size-for-all” does not fit the vast heterogeneity in recovery observed in stroke survivors. In this article, the authors propose a novel framework that personalizes the application of non-invasive brain stimulation based on understanding of the structural anatomy, neural connectivity, and task attributes. They further provide experimental support for this idea with data from severely impaired stroke survivors that validate the proposed framework.

The issue of heterogeneity poststroke is also addressed by Lefebvre and Liew in “Anatomical Parameters of tDCS to modulate the motor system after stroke: A review.” These authors discuss the variability in research using tDCS for the poststroke population. According to the authors, the most likely sources of variability include the heterogeneity of poststroke populations and the experimental paradigms. Individually based variability of results could be related to various factors including: (1) molecular factors such as baseline measures of GABA, levels of dopamine receptor activity, and propensity of brain-derived neurotropic factor expression; (2) time poststroke, (3) lesion location; (4) type of stroke; and (5) level of poststroke motor impairment. Variability related to experimental paradigms include the timing of the stimulation (pre- or post-training), the experimental task, and whether the protocol emphasizes motor performance (a temporary change in motor ability) or motor learning based (more permanent change in motor ability). Finally, the numerous possibilities of electrode placement, neural targets, and the different setups (monocephalic versus bi-hemispheric) add further complexity. For future work with the poststroke population, the authors suggest that tDCS experimental paradigms explore individualized neural targets determined by neuronavigation.

In another exciting study in this issue, Estes et al. tackle the timely topic of spinal reflex excitability modulated by motor priming in individuals with spinal cord injury. The authors choose to test four non-pharmacological interventions: stretching, continuous passive motion, transcranial direct current stimulation, and transcutaneous spinal cord stimulation to reduce spasticity. Three out of four techniques were associated with reduction in spasticity immediately after treatment, to an extent comparable to pharmacological approaches. These priming approaches provide a low-cost and low-risk alternative to anti-spasticity medications.

In another clinical study in individuals with spinal cord injury, Gomes-Osman et al. examined effects of two different approaches to priming. Participants were randomized to either peripheral nerve stimulation (PNS) plus functional task practice, PNS alone, or conventional exercise therapy. The findings were unexpected. There was no change in somatosensory function or power grip strength in any of the groups. Interestingly, all of the interventions produced changes in precision grip of the weaker hand following training. However, only PNS plus functional task practice improved precision grip in both hands. The authors found that baseline corticospinal excitability were significantly correlated to changes in precision grip strength of the weaker hand. The lack of change in grip strength in any of the groups was surprising. Previous evidence suggests, however, that the corticomotor system is more strongly activated during precision grip as compared to power grip, and the authors suggest that interventions targeting the corticomotor system (i.e., various priming methods) may more strongly effect precision grip.

Overall, this special issue brings together an array of original research articles and reviews that further enhance our understanding of motor priming for motor recovery with an emphasis on neural mechanisms and clinical implementation. We hope that the studies presented encourage future studies on motor priming paradigms to optimize the potential for functional recovery in the neurologically disadvantaged population, and further our understanding of neuroplasticity after injury.

Author Contributions

SM and MS have made a substantial, direct, and intellectual contribution to the work and approved it for publication.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding

SM is supported by funding from the National Institutes of Health (R01HD075777).

Source: Frontiers | Editorial: Motor Priming for Motor Recovery: Neural Mechanisms and Clinical Perspectives | Neurology

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[Abstract] Virtual reality and non-invasive brain stimulation in stroke: How effective is their combination for upper limb motor improvement?

Abstract:

Upper limb (UL) hemiparesis is frequently a disabling consequence of stroke. The ability to improve UL functioning is associated with motor relearning and experience dependent neuroplasticity. Interventions such as non-invasive brain stimulation (NIBS) and task-practice in virtual environments (VEs) can influence motor relearning as well as adaptive plasticity. However, the effectiveness of a combination of NIBS and task-practice in VEs on UL motor improvement has not been systematically examined. The objective of this review was to examine the evidence regarding the effectiveness of combining NIBS with task-practice in VEs on UL motor impairment and activity levels. A systematic review of the published literature was conducted using standard methodology. Study quality was assessed using the PEDro scale and Down’s and Black checklist. Four studies examining the effects of a combination of NIBS (involving transcranial direct current stimulation; tDCS and repetitive transcranial magnetic stimulation; rTMS) were retrieved. Of these, three studies were randomized controlled trials (RCTs) and one was a cross-sectional study. There was 1a level evidence that the combination of NIBS and task-practice in a VE was beneficial in the sub-acute stage. A combination of training in a VE with rTMS as well as tDCS was beneficial for motor improvements in the UL in sub-acute stage of stroke (1b level). The combination was not found to be superior compared to task practice in VEs alone in the chronic stage (1b level). The results suggest that people with stroke may be capable of improving levels of motor impairment and activity in the sub-acute stage if their rehabilitation program involves a combination on NIBS and VE training. Emergent questions regarding the use of more sensitive outcomes, different types of stimulation parameters, locations and training environments still need to be addressed.

Source: Virtual reality and non-invasive brain stimulation in stroke: How effective is their combination for upper limb motor improvement? – IEEE Xplore Document

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[ARTICLE] Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis – Full Text

 

Abstract

Introduction Dexterity is described as coordinated hand and finger movement for precision tasks. It is essential for day-to-day activities like computer use, writing or buttoning a shirt. Integrity of brain motor networks is crucial to properly execute these fine hand tasks. When these networks are damaged, interventions to enhance recovery are frequently accompanied by unwanted side effects or limited in their effect. Non-invasive brain stimulation (NIBS) are postulated to target affected motor areas and improve hand motor function with few side effects. However, the results across studies vary, and the current literature does not allow us to draw clear conclusions on the use of NIBS to promote hand function recovery. Therefore, we developed a protocol for a systematic review and meta-analysis on the effects of different NIBS technologies on dexterity in diverse populations. This study will potentially help future evidence-based research and guidelines that use these NIBS technologies for recovering hand dexterity.

Methods and analysis This protocol will compare the effects of active versus sham NIBS on precise hand activity. Records will be obtained by searching relevant databases. Included articles will be randomised clinical trials in adults, testing the therapeutic effects of NIBS on continuous dexterity data. Records will be studied for risk of bias. Narrative and quantitative synthesis will be done.

Strengths and limitations of this study

  • This is a novel systematic review and meta-analysis focusing specifically on dexterity.

  • We use continuous data not dependent on the evaluator or participant.

  • This work will potentially help future evidence-based research and guidelines to refine non-invasive brain stimulation.

Introduction

The hand’s somatotopy is extensively represented in the human motor cortex.1 2 Phylogenetically, this relates to the development of corticomotoneuronal cells that specialise in creating patterns of muscle activity that synergises into highly skilled movements.3 This organised hand-and-finger movement to use objects during a specific task is known as dexterity.4 Evolutionary, dexterity played a pivotal role in human survival and is fundamental to actives of daily living, and hence quality of life.5 6

This precision motor movement relies on integration of information from the cerebral cortex, the spinal cord, several neuromusculoskeletal systems and the external world to coordinate finger force control, finger independence, timing and sequence performance.7 During these tasks, multivoxel pattern decoding shows bilateral primary motor cortex activation (M1), which was responsible for muscle recruitment timing and hand movement coordination.8 9 This is related to motor cortex connectivity through the corpus callosum, to motor regions of the cerebellum and white matter integrity.10–15 Adequate motor output translates into successfully executed tasks, like picking up objects, turning over cards, manipulating cutlery, writing, using computer–hand interfaces like smartphones, playing an instrument and performing many other similarly precise skills.16

These motor tasks are negatively impacted when motor output networks are affected, as seen in stroke or Parkinson’s disease.17 18 Therapeutic interventions that restore these damaged motor networks can be vital to restore fine motor movement after injury occurs. Pharmaceutical approaches often lead to adverse effects such as dyskinesias in Parkinson’s disease. Moreover, even after intensive rehabilitation programmes, only about 5%–20% of patients with stroke fully recover their motor function.19–21 Non-invasive brain stimulation (NIBS) techniques, like transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), are proposed adjuvant or stand-alone interventions to target these affected areas and improve fine motor function.22 23 Briefly, these NIBS interventions are shown to influence the nervous system’s excitability and modulate long-term plasticity, which may be beneficial to the brain’s recovery of functions after injury.24–27

Fine hand motor ability is not studied as much in previous reviews of NIBS. Specifically, one narrative review focuses on rTMS in affected hand recovery poststroke; however, it does not consider the implications of varying International Classification of Functioning, Disability and Health (ICF) domains, data types and rater dependent outcomes, and its interpretability is limited without quantitative synthesis.28–31 The overarching conclusion was supportive of rTMS for paretic hand recovery, though with limited data to support its regular use, and a pressing need to study individualised patient parameters.28 One meta-analysis had positive and significant results when specifically studying the effects of rTMS on finger coordination and hand function after stroke.32 However, while various meta-analysis, and another systematic review, studied upper-limb movement after NIBS in distinct populations, they did not focus on precise hand function, pooled upper-limb outcomes with hand outcomes and presented mixed results.33–38

Motivated by this gap in the evidence for NIBS in dexterity, we will do a systematic review and meta-analysis of the literature on these brain stimulation technologies using outcomes that focus exactly on manual dexterity. These outcomes will be continuous and not dependent on the participant’s or rater’s observation (ie, they will be measured in seconds, or number of blocks/pegs placed, and not by an individual’s interpretation). They will be comprised of multiple domains as defined by the ICF, providing an appreciation of function rather than only condition or disease.29–31 By focusing on the ICF model, we will be able to study dexterity across a larger sample of studies, NIBS techniques and conditions in order to provide a better understanding of brain stimulation efficacy on hand function in various populations.[…]

Continue —. Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis | BMJ Open

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[ARTICLE] Non-Invasive Brain Stimulation to Enhance Upper Limb Motor Practice Poststroke: A Model for Selection of Cortical Site – Full Text

Motor practice is an essential part of upper limb motor recovery following stroke. To be effective, it must be intensive with a high number of repetitions. Despite the time and effort required, gains made from practice alone are often relatively limited, and substantial residual impairment remains. Using non-invasive brain stimulation to modulate cortical excitability prior to practice could enhance the effects of practice and provide greater returns on the investment of time and effort. However, determining which cortical area to target is not trivial. The implications of relevant conceptual frameworks such as Interhemispheric Competition and Bimodal Balance Recovery are discussed. In addition, we introduce the STAC (Structural reserve, Task Attributes, Connectivity) framework, which incorporates patient-, site-, and task-specific factors. An example is provided of how this framework can assist in selecting a cortical region to target for priming prior to reaching practice poststroke. We suggest that this expanded patient-, site-, and task-specific approach provides a useful model for guiding the development of more successful approaches to neuromodulation for enhancing motor recovery after stroke.

Poststroke Arm Impairment

Upper limb motor impairment following stroke is highly prevalent and often persists even after intensive rehabilitation efforts (14). It is also one of the most disabling of stroke sequela, limiting functional independence and precluding return to work and other roles (5).

Upper extremity motor control relies heavily on input transmitted via the corticospinal tract (CST). The CST descends through the posterior limb of the internal capsule, an area vulnerable to middle cerebral artery stroke and in which CST fibers are densely packed. Thus, even a small lesion in this location can have devastating effects on motor function (69). A loss of voluntary wrist and finger extension is particularly common and appears to be related to the extent of CST damage (10). There is also evidence that those who retain wrist extension and have considerable CST sparing are more likely to be responsive to existing therapies (7811).

However, even individuals who lack voluntary wrist and finger extension often retain some ability to move the shoulder and elbow. Unfortunately, only a few stereotyped movement patterns can be performed and these are often not functional. The combination of shoulder flexion with elbow extension that is required for most functional reaching tasks, for example, is frequently lost. Nevertheless, previous studies have demonstrated that reaching practice with trunk restraint can improve unconstrained reaching ability, even in patients who lack wrist and finger extension (1215). Still, a great deal of time and effort is required and the improvements are relatively small.

Non-Invasive Brain Stimulation

Non-invasive brain stimulation offers a potential method of enhancing the effects of practice and thus giving patients greater returns on their investment of time and effort. Approaches to non-invasive brain stimulation are rapidly expanding but generally fall into two major categories: transcranial magnetic stimulation (TMS) and transcranial electrical stimulation [TES; see Ref. (16) for overview of non-invasive techniques for neuromodulation]. These modalities are applied to the scalp overlying a specific cortical area that is being targeted. The level of spatial specificity varies depending on many factors including the modality used (TMS is generally more precise than TES), the stimulation intensity (higher intensity results in a more widespread effect), and the architecture of the underlying tissue. The excitability of the underlying pool of neurons can be modulated by varying stimulation parameters such as the frequency and temporal pattern of the stimuli. Therefore, stimulation can be used to temporarily inhibit or facilitate the underlying cortical area for a sustained period of time after the stimulation ends (usually 20–40 min). In this way, non-invasive brain stimulation could be used to “prime” relevant cortical areas before a bout of practice, potentially enhancing the effects of practice. However, there is little guidance for how such cortical sites might be selected and in which direction (inhibition or facilitation) their activity should be modulated. Conceptual models that could offer such guidance are considered below.

Mechanistic Models to Guide Neuromodulation

Continue —> Frontiers | Non-Invasive Brain Stimulation to Enhance Upper Limb Motor Practice Poststroke: A Model for Selection of Cortical Site | Neurology

Figure 1. On randomly delivered trials, transcranial magnetic stimulation (TMS) perturbation was applied just after a “Go” cue. The effect of this pre-movement perturbation on the speed of the subsequent reaching movement is expressed relative to that in trials with no TMS perturbation. The amount of slowing due to TMS perturbation of the lesioned vs. non-lesioned hemispheres is shown for patients with good structural reserve (left) and patients with poor structural reserve (right).

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[Abstract] The treatment of fatigue by non-invasive brain stimulation

Summary

The use of non-invasive brain neurostimulation (NIBS) techniques to treat neurological or psychiatric diseases is currently under development. Fatigue is a commonly observed symptom in the field of potentially treatable pathologies by NIBS, yet very little data has been published regarding its treatment. We conducted a review of the literature until the end of February 2017 to analyze all the studies that reported a clinical assessment of the effects of NIBS techniques on fatigue. We have limited our analysis to repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). We found only 15 studies on this subject, including 8 tDCS studies and 7 rTMS studies. Of the tDCS studies, 6 concerned patients with multiple sclerosis while 6 rTMS studies concerned fibromyalgia or chronic fatigue syndrome. The remaining 3 studies included patients with post-polio syndrome, Parkinson’s disease and amyotrophic lateral sclerosis. Three cortical regions were targeted: the primary sensorimotor cortex, the dorsolateral prefrontal cortex and the posterior parietal cortex. In all cases, tDCS protocols were performed according to a bipolar montage with the anode over the cortical target. On the other hand, rTMS protocols consisted of either high-frequency phasic stimulation or low-frequency tonic stimulation. The results available to date are still too few, partial and heterogeneous as to the methods applied, the clinical profile of the patients and the variables studied (different fatigue scores) in order to draw any conclusion. However, the effects obtained, especially in multiple sclerosis and fibromyalgia, are really carriers of therapeutic hope.

Source: The treatment of fatigue by non-invasive brain stimulation

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[Abstract] Bilateral sequential motor cortex stimulation and skilled task performance with non-dominant hand

Highlights

  • Both, contralateral M1 iTBS and ipsilateral M1 cTBS improved non-dominant skilled-task performance.
  • Bilateral sequential M1 TBS (contralateral cTBS followed by ipsilateral iTBS) improved skilled-task performance more than unilateral or sham TBS.
  • Bilateral sequential M1 TBS may be particularly effective in improving motor learning, also in the neurorehabilitation setting.

Abstract

Objective

To check whether bilateral sequential stimulation (BSS) of M1 with theta burst stimulation (TBS), using facilitatory protocol over non-dominant M1 followed by inhibitory one over dominant M1, can improve skilled task performance with non-dominant hand more than either of the unilateral stimulations do. Both, direct motor cortex (M1) facilitatory non-invasive brain stimulation (NIBS) and contralateral M1 inhibitory NIBS were shown to improve motor learning.

Methods

Forty right-handed healthy subjects were divided into 4 matched groups which received either ipsilateral facilitatory (intermittent TBS [iTBS] over non-dominant M1), contralateral inhibitory (continuous TBS [cTBS] over dominant M1), bilateral sequential (contralateral cTBS followed by ipsilateral iTBS), or placebo stimulation. Performance was evaluated by Purdue peg-board test (PPT), before (T0), immediately after (T1), and 30 min after (T2) an intervention.

Results

In all groups and for both hands, the PPT scores increased at T1 and T2 in comparison to T0, showing clear learning effect. However, for the target non-dominant hand only, immediately after BSS (at T1) the PPT scores improved significantly more than after either of unilateral interventions or placebo.

Conclusion

M1 BSS TBS is an effective intervention for improving motor performance.

Significance

M1 BSS TBS seems as a promising tool for motor learning improvement with potential uses in neurorehabilitation.

Source: Bilateral sequential motor cortex stimulation and skilled task performance with non-dominant hand – Clinical Neurophysiology

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[WEB SITE] Electrical brain stimulation could boost benefits of stroke rehabilitation. | Science | The Guardian

Research indicates that transcranial direct current stimulation (tCDS) during rehabilitation therapy might help stroke patients recover more movement

Scans showing the effects of hemorrhagic and ischemic stroke.

Scans showing the effects of hemorrhagic and ischemic stroke on the brain. Photograph: Alamy

Electrical brain stimulation could benefit stroke patients by boosting the effects of rehabilitation therapy, new research suggests.

Writing in the journal Science Translational Medicine, the authors reveal that patients who were given electrical brain stimulation during a rehabilitation programme performed better on a range of tasks than those taking part in the rehabilitation programme.

“It is an exciting message because there is so much frustration about people not reaching their true recovery potential,” said Professor Heidi Johansen-Berg, an author of the study from the University of Oxford, highlighting the fact that the cost of programmes and limited availability of therapists often restricts the amount of rehabilitation offered to patients.

To probe the effects of brain stimulation, the researchers chose 24 patients who had experienced a stroke at least six months before, and who had difficulties with moving one hand. The participants were then split into two groups.

The first group underwent nine consecutive days of rehabilitation training, with each session lasting an hour. For the first 20 minutes, the patients had two electrodes placed on their heads and a direct current applied, a process known as anodal transcranial direct current stimulation (tDCS). This is stimulation is thought to prime the brain for learning.

The second group also underwent the nine-day programme, but while they too had electrodes placed on their head for the first 20 minutes, the current was turned off after the first 10 seconds, leading to a placebo trial.

The results indicate that brain stimulation bolstered the effect of the rehabilitation therapy, with patients who underwent the stimulation scoring appreciably higher on two of the tests – those related to carrying out particular tasks with the hand such as picking up a paper-clip – in assessments carried out three months after the therapy. For third test, which measured effects such as the strength of grip, brain stimulation was not linked to improvements.

“If we take at face value what the results are telling us, it is that the stimulation doesn’t completely change the way that the brain can produce a movement, in that it doesn’t make you stronger, but it makes the brain better at being able to carry out a particular task like lifting up an object,” said Johansen-Berg.

However not everyone is convinced. Jane Burridge, professor of restorative neuroscience at the University of Southampton, who was not involved with the study, said the smaller effect for the third test could simply be down to the small size of the study. “You do need to have bigger trials to be certain of the results,” she said.

The research also found that patients who underwent the brain stimulation had larger increases in activity in regions of the brain associated with movement than those who had been given the placebo treatment – an effect that was seen from fMRI scans taken immediately after the nine-day programme and one month later.

“What is particularly important about [the study] is that it does relate the functional improvements with the neuroimaging changes – and that is very encouraging,” said Burridge.

But Burridge also cautions that the results should not be taken as a sign that brain stimulation will benefit all stroke patients. “One has to remember that this is one quite small study,” she said. “The overall view at the moment of when we put all the data [from many studies] together is that there is no clear benefit.”

Johansen-Berg also admits the new research has its limitations. “One thing it doesn’t allow us to do at all is get at the question of variability ,” she says. “We wouldn’t expect this to work for everybody, there will be some people it will work well for and some people who it won’t and we haven’t got anything like the numbers you’d need to tease that apart.”

The results were welcomed by health charities. “This study is an important step toward larger trials to test the effectiveness of non-invasive, electrical brain stimulation to improve the motor recovery of stroke survivors and support their rehabilitation after stroke,” said Dr Shamim Quadir of the Stroke Association. “Stroke is one of the largest causes of disability, and more than half of stroke survivors are left dependent on others for help with everyday activities. It is crucial that we find alternative ways to help improve the recovery rates from this devastating condition.”

But Dr Nick Ward from University College London warns that the study is unlikely to lead to a change in treatment programmes any time soon. “I would call this a proof of principle study,” he said. “This is not something that you can translate into the NHS or any other clinical service immediately.”

For Ward, the most interesting revelation is the level of improvement shown by the patients who did not receive brain stimulation, calling the results “dramatic”. While he cautions that the size of the effect might be down to the very selective nature of the group, if shown to apply more generally it would support the idea that “doing more physical therapy is a good thing.”

Johansen-Berg also believes the research offers a wider message of hope. “With the two weeks of intense therapy, both groups show significant improvement, it is just that they are slightly boosting that with the tDCS,” she said. “ What this shows is if you do two weeks of intensive practice with your bad hand, you will get much better.”

Source: Electrical brain stimulation could boost benefits of stroke rehabilitation | Science | The Guardian

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[Abstract] Enhancement of motor relearning and functional recovery in stroke patients: non-invasive strategies for modulating the central nervous system. – PubMed

INTRODUCTION: Most of the stroke survivors do not recover the basal state of the affected upper limb, suffering from a severe disability which remains during the chronic phase of the illness. This has an extremely negative impact in the quality of life of these patients. Hence, neurorehabilitation strategies aim at the minimization of the sensorimotor dysfunctions associated to stroke, by promoting neuroplasticity in the central nervous system.

DEVELOPMENT: Brain reorganization can facilitate motor and functional recovery in stroke subjects. None-theless, after the insult, maladaptive neuroplastic changes can also happen, which may lead to the appearance of certain sensori-motor disorders such as spasticity. Noninvasive brain stimulation strategies, like transcranial direct current stimulation or transcranial magnetic stimulation, are widely used techniques that, when applied over the primary motor cortex, can modify neural networks excitability, as well as cognitive functions, both in healthy subjects and individuals with neurological disorders. Similarly, brain-machine-interface systems also have the potential to induce a brain reorganization by the contingent and simultaneous association between the brain activation and the peripheral stimulation.

CONCLUSION: This review describes the positive effects of the previously mentioned neurorehabilitation strategies for the enhancement of cortical reorganization after stroke, and how they can be used to alleviate the symptoms of the spasticity syndrome.

Source: [Enhancement of motor relearning and functional recovery in stroke patients: non-invasive strategies for modulating the central nervous system]. – PubMed – NCBI

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