Archive for category tDCS/rTMS

[ARTICLE] Combining transcranial direct-current stimulation with gait training in patients with neurological disorders: a systematic review – Full Text

Abstract

Background

Transcranial direct-current stimulation (tDCS) is an easy-to-apply, cheap, and safe technique capable of affecting cortical brain activity. However, its effectiveness has not been proven for many clinical applications.

Objective

The aim of this systematic review was to determine whether the effect of different strategies for gait training in patients with neurological disorders can be enhanced by the combined application of tDCS compared to sham stimulation. Additionally, we attempted to record and analyze tDCS parameters to optimize its efficacy.

Methods

A search in Pubmed, PEDro, and Cochrane databases was performed to find randomized clinical trials that combined tDCS with gait training. A chronological filter from 2010 to 2018 was applied and only studies with variables that quantified the gait function were included.

Results

A total of 274 studies were found, of which 25 met the inclusion criteria. Of them, 17 were rejected based on exclusion criteria. Finally, 8 trials were evaluated that included 91 subjects with stroke, 57 suffering from Parkinson’s disease, and 39 with spinal cord injury. Four of the eight assessed studies did not report improved outcomes for any of its variables compared to the placebo treatment.

Conclusions

There are no conclusive results that confirm that tDCS can enhance the effect of the different strategies for gait training. Further research for specific pathologies, with larger sample sizes and adequate follow-up periods, are required to optimize the existing protocols for applying tDCS.

Introduction

Difficulty to walk is a key feature of neurological disorders [1], so much so that recovering and/or maintaining the patient’s walking ability has become one of the main aims of all neurorehabilitation programs [2]. Additionally, the loss of this ability is one of the most significant factors negatively impacting on the social and professional reintegration of neurological patients [3].

Strategies for gait rehabilitation traditionally focus on improving the residual ability to walk and compensation strategies. Over the last years, a new therapeutic paradigm has been established based on promoting neuroplasticity and motor learning, which has led to the development of different therapies employing treadmills and partial body-weight support, as well as robotic-assisted gait training [4]. Nevertheless, these new paradigms have not demonstrated superior results when compared to traditional therapies [5,6,7], and therefore recent studies advise combining therapies to enhance their therapeutic effect via greater activation of neuroplastic mechanisms [8].

Transcranial direct-current stimulation (tDCS) is an intervention for brain neuromodulation consisting of applying constant weak electric currents on the patient’s scalp in order to stimulate specific brain areas. The application of the anode (positive electrode) to the primary motor cortex causes an increase in neuron excitability whereas stimulation with the cathode (negative electrode) causes it to decrease [9].

The effectiveness of tDCS has been proven for treating certain pathologies such as depression, addictions, fibromyalgia, or chronic pain [10]. Also, tDCS has shown to improve precision and motor learning [11] in healthy volunteers. Improvements in the functionality of upper limbs and fine motor skills of the hand with paresis have been observed in patients with stroke using tDCS, although the results were somewhat controversial [1213]. Similarly, a Cochrane review on the effectiveness of tDCS in treating Parkinson’s disease highlights the great potential of the technique to improve motor skills, but the significance level of the evidence was not enough to clearly recommend it [14]. In terms of gait rehabilitation, current studies are scarce and controversial [10].

Furthermore, tDCS is useful not only as a therapy by itself but also in combination with other rehabilitation strategies to increase their therapeutic potential; in these cases, the subjects’ basal activity and the need for combining the stimulation with the behavior to be enhanced have been highlighted. Several studies have combined tDCS with different modalities of therapeutic exercising, such as aerobic exercise to increase the hypoalgesic effect in patients with fibromyalgia [15] or muscle strengthening to increase functionality in patients suffering from knee osteoarthritis [16]. Along these lines, various studies have combined tDCS with gait training in patients with neurological disorders, obtaining rather disparate outcomes [17,18,19,20]. As a result, the main aim of this systematic review was to determine whether the application of tDCS can enhance the effectiveness of other treatment strategies for gait training. Additionally, as a secondary objective, we attempted to record and identify the optimal parameters of the applied current since they are key factors for its effectiveness. […]

 

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[Abstract + References] Motor stroke recovery after tDCS: a systematic review

Abstract

The purpose of the present study was to investigate the effects of transcranial direct current stimulation (tDCS) on motor recovery in adult patients with stroke, taking into account the parameters that could influence the motor recovery responses. The second aim was to identify the best tDCS parameters and recommendations available based on the enhanced motor recovery demonstrated by the analyzed studies. Our systematic review was performed by searching full-text articles published before February 18, 2019 in the PubMed database. Different methods of applying tDCS in association with several complementary therapies were identified. Studies investigating the motor recovery effects of tDCS in adult patients with stroke were considered. Studies investigating different neurologic conditions and psychiatric disorders or those not meeting our methodologic criteria were excluded. The main parameters and outcomes of tDCS treatments are reported. There is not a robust concordance among the study outcomes with regard to the enhancement of motor recovery associated with the clinical application of tDCS. This is mainly due to the heterogeneity of clinical data, tDCS approaches, combined interventions, and outcome measurements. tDCS could be an effective approach to promote adaptive plasticity in the stroke population with significant positive premotor and postmotor rehabilitation effects. Future studies with larger sample sizes and high-quality studies with a better standardization of stimulation protocols are needed to improve the study quality, further corroborate our results, and identify the optimal tDCS protocols.

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[WEB SIDE] RPW Technology Announces The Launch Of Liftid Neurostimulation

OSSINING, N.Y.Aug. 16, 2019 /PRNewswire/ — RPW Technology, LLC introduces Liftid Neurostimulation (www.GetLiftid.com), a transcranial direct current stimulation (tDCS) recreational device for consumers that can improve attention, productivity, and memory through mild electrical stimulation. Liftid uses a constant, low-level electric current, passed through two electrodes placed on the forehead area, to stimulate the brain. tDCS is one of the hottest categories in neuroscience today and supported by over 4,000 published studies.

Maximize attention and elevate performance with LIFTiD Neurostimulation.

 

Dr. Ted Schwartz, MD, a New York based neurosurgeon and RPW’s lead scientist, explains, “As has been shown in several studies, tDCS delivers a small amount of electrical current to the cerebral cortex, rendering neurons in the brain more likely to fire. As a result, the user demonstrates increased abilities, alertness and focus.”

In today’s world, most working professionals, college and grad students, video gamers, musicians, and athletes are chemically stimulating their brains through caffeine, sugar, snacks, and performance enhancers. Liftid Neurostimulation uses a safe and effective technology as an alternative to these forms of chemical stimulation.

RPW Technology is proud to be on the forefront of this emerging technology by bringing to market a tDCS device for healthy individuals (ages 18 & up) that is stylish, extremely lightweight (70 grams) including a soft, comfortable, adjustable headband, and easy to operate. Designed and developed by a team of world renowned neuroscientists, Liftid is preset for a 20 minute stimulation session and has many unique features built-in to the device. Using Liftid Neurostimulation for 20 minutes a day trains the brain to maximize attention, focus, alertness, and memory, thus putting the Liftid user in the right mindset to accomplish tasks and elevate performance.

For more information, purchase, and/or instructional video, please visit the Liftid Neurostimulation website at: www.GetLiftid.com. Unit price is $149.00, which includes an attractive and functional storage case with custom accessories and free shipping within the United States. Liftid is packaged for retail sales.

RPW Technology is a New York startup dedicated to the development and marketing of transcranial electrical stimulation devices. The company, in association with Dr. Schwartz and several neuroscientists, set out to develop a high quality, hi-tech, recreational tDCS device to introduce to consumers worldwide.

Contact for RPW Technology, LLC:
Bridget Argana
Orca Communications Unlimited, LLC
bridget.argana@orcapr.com
(480) 231-3582

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SOURCE RPW Technology, LLC

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[WEB SITE] What is neurohacking and can it actually rewire your brain?

Marc Bordons / Stocksy

What is neurohacking and can it actually rewire your brain?

Although at one point, “hack” referred to a creative solution to a tech problem, the term can apply to pretty much anything now. There are kitchen hacks, productivity hacks, personal finance hacks. Brain hacks, or neurohacks, are among the buzziest, though, thanks largely to the Silicon Valley techies who often swear by them as a way to boost their cognitive function, focus, and creativity. Mic asked a neuroscientist to explain neurohacking, which neurohacking methods are especially promising, which are mostly hype, and how to make neurohacking work for you.

First things first: Neurohacking, is a broad umbrella term that encompasses anything that involves “manipulating brain function or structure to improve one’s experience of the world,” says neuroscientist Don Vaughn of Santa Clara University and the University of California, Los Angeles. Like the other myriad forms of hacking, neurohacking uses an engineering approach, treating the brain as a piece of hardware that can be systematically modified and upgraded.

Neurohacking techniques can fall under a number of categories — here are a few of the most relevant ones, as well as the thinking behind them.

Brain stimulation

This involves applying an electric or magnetic field to certain regions of the brain in non-neurotypical people to make their activity more closely resemble that seen in a neurotypical brain. In 2008, the Food and Drug Administration approved transcranial magnetic stimulation (TMS) — a noninvasive form of brain stimulation which delivers magnetic pulses to the brain in a noninvasive manner — for major depression. Since then, the FDA has also approved TMS for pain associated with migraines with auras, as well as obsessive-compulsive disorder. Established brain stimulation techniques (such as TMS or electroconvulsive therapy) performed by an expert provider, such as a psychiatrist or neuroscientist, are generally safe, Vaughn says.

Neurofeedback

This one involves using a device that measures brain activity, such as an electroencephalogram (EEG) or a functional magnetic resonance imaging (fMRI) machine. People with neuropsychological disorders receive feedback on their own brain activity — often in the form of images or sound — and focus on trying to make it more closely resemble the brain activity in a healthy person, Vaughn says. This could happen through changing their thought patterns, Vaughn says. Another possibility is that the feedback itself, or the person’s thoughts about the feedback, may somehow lead to a change in their brain’s wiring.

Reducing cognitive load

This means minimizing how much apps, devices, and other tech compete for your attention. Doing so can sharpen and sustain your focus, or what Vaughn refers to as your attention quotient (AQ). To boost his AQ, Vaughn listens to brown noise, which he likens to “white noise, but deeper.” (Think the low rush of a waterfall versus pure static.) He also chews gum, which he says provides an outlet for his restless “monkey mind” while still allowing him to focus on the task at hand.

Reducing cognitive load can also deepen your connection with others. Vaughn uses Voicea, an app based on an AI assistant that takes and store notes of meetings, whether over the phone or in-person, allowing him to focus solely on the conversation, not on recording it. “If we can quell those disruptions that occur because of the way work is done these days, it will allow us to focus and be more empathic with each other,” he says.

Monitoring sleep

Tracking your sleep patterns and adjusting them accordingly. Every night, you go through around five or so stages of sleep, each one deeper than the last. “People are less groggy and make fewer errors when they wake up in a lighter stage of sleep,” Vaughn says. He uses Sleep Cycle, an app that tracks your sleep patterns based on your movements in bed to rouse you during your lightest sleep stage.

Andrey Popov / Shutterstock

Microdosing

Microdosing is the routinely consumption of teensy doses of psychedelics like LSD, ecstasy, or magic mushrooms. Many who practice microdosing follow the regimen recommended by James Fadiman, psychologist and author of The Psychedelic Explorer’s Guide: Safe, Therapeutic, and Sacred Journeys: a twentieth to a tenth of a regular dose, once every three days for about a month. While a regular dose may make you trip, a microdose has subtler effects, with some users reporting, for instance, enhanced energy and focus, per The Cut.

Nootropics

These are OTC supplements or drugs taken to enhance cognitive function. They range from everyday caffeine and vitamin B12 (B12 deficiency has been associated with cognitive decline) to prescription drugs like Ritalin and Adderall, used to treat ADHD and narcolepsy, as well as Provigil (modafinil), used to treat extreme drowsiness resulting from narcolepsy and other sleep disorder. (All three of these drugs promote wakefulness.) The science behind nootropic supplements in particular remains rather murky, though.

Does neurohacking work, though?

Vaughn finds microdosing, neurostimulation, and neurofeedback especially promising for neuropsychological disorders. Although studies suggest that larger doses of psychedelics could help with disorders such as PTSD and treatment-resistant major depression, there are few studies on microdosing psychedelics. “The little science that has been done…is mixed—perhaps slightly positive,” Vaughn says. “Microdosing is promising mainly because of anecdotal evidence.” Meanwhile, neurostimulation can be used noninvasively in some cases, and TMS has already received FDA approval for a handful of conditions. Neurofeedback is not only non-invasive, but offers immediate feedback, and studies suggest it could be effective for PTSD and addiction.

But it’s important to note that just because these methods could positively alter brain function in people with neuropsychological disorders, that “doesn’t mean it’s going to take a normal system and make it superhuman,” Vaughn says. “I think there are lots of small hacks to be done that could add up to something big,” rather than huge hacks that can vastly upgrade cognitive function, a la Limitless. Thanks to millions of years of evolution, the human brain is already pretty damn optimized. “I just don’t know how much more we can tweak it to make it better,” Vaughn says.

As far as enhancements for neurotypical brains, he says that “you’ll probably see a much greater improvement” from removing distractions in your environment to reduce cognitive load than say, increasing your B12 intake — which brings us to an important disclaimer about nootropic supplements in particular. As with all supplements, they aren’t FDA-regulated, meaning that companies that sell them don’t need to provide evidence that they’re safe or effective. Vaughn recommends trying nootropics that research has shown to be safe and effective, like B12 or caffeine.

How can I start neurohacking?

As tempting as it is, adopting every neurohack under the sun is “not the answer,” Vaughn says. Remember, everyone is different. While your best friend may gush about how much her mood has improved since she began microdosing shrooms, your brain might not respond to microdosing—or maybe taking psychedelics just doesn’t align with your ethics.

Start by exploring different neurohacks, and of course, be skeptical of any product that makes outrageous claims. Since neurofeedback isn’t a common medical treatment, talk to your doctor about enrolling in academic studies on neurofeedback, or companies that offer it if you’re interested, Vaughn says. You should also talk to your doctor if you want to try brain stimulation. A doctor can prescribe you Adderall, Ritalin, or Provigil but only for their indicated medical uses, not for cognitive enhancement.

Ultimately, neurohacks are tools, Vaughn says. “You have to find the one that works for you.” If anything, taking this DIY approach to improving your brain function will leave you feeling empowered, a benefit that probably rivals anything a supplement or sleep tracking app could offer.

 

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[Abstract] Comparison between Transcranial Direct Current Stimulation and Acupuncture on Upper Extremity Rehabilitation in Stroke: A Single-Blind Randomized Controlled Trial

Abstract

Objective: To compare the effects of transcranial direct current stimulation (TDCS) with traditional Chinese acupuncture on upper-extremity (UE) function among patients with stroke.

Materials and Methods: Participants with subacute to chronic stroke who had moderate to severe UE functional impairment were randomly allocated to the TDCS or electro-acupuncture group, then underwent three weeks of physical therapy and occupational therapy, with 20 minutes of a-TDCS (2 mA) or electro-acupuncture applied during training once weekly. Primary outcome was determined using the Fugl-Meyer Assessment of motor recovery at 1-month follow-up.

Results: The 18 participants were allocated into two groups. Fugl-Meyer Assessment increased in both the TDCS and electroacupuncture groups (5.00±3.08, p=0.001 and 7.4±4.9, p=0.002, respectively). However, no difference was found between groups, and no significant difference was observed in grip strength and task specific performance in both groups.

Conclusion: The application of TDCS might provide benefits in recovering hand motor function among patients with subacute to chronic stroke but does not go beyond those of electro-acupuncture.

via Comparison between Transcranial Direct Current Stimulation and Acupuncture on Upper Extremity Rehabilitation in Stroke: A Single-Blind Randomized Controlled Trial | Hathaiareerug | JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND

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[Abstract] Role of Interhemispheric Cortical Interactions in Poststroke Motor Function

Background/Objective. We investigated interhemispheric interactions in stroke survivors by measuring transcranial magnetic stimulation (TMS)–evoked cortical coherence. We tested the effect of TMS on interhemispheric coherence during rest and active muscle contraction and compared coherence in stroke and older adults. We evaluated the relationships between interhemispheric coherence, paretic motor function, and the ipsilateral cortical silent period (iSP).

Methods. Participants with (n = 19) and without (n = 14) chronic stroke either rested or maintained a contraction of the ipsilateral hand muscle during simultaneous recordings of evoked responses to TMS of the ipsilesional/nondominant (i/ndM1) and contralesional/dominant (c/dM1) primary motor cortex with EEG and in the hand muscle with EMG. We calculated pre- and post-TMS interhemispheric beta coherence (15-30 Hz) between motor areas in both conditions and the iSP duration during the active condition.

Results. During active i/ndM1 TMS, interhemispheric coherence increased immediately following TMS in controls but not in stroke. Coherence during active cM1 TMS was greater than iM1 TMS in the stroke group. Coherence during active iM1 TMS was less in stroke participants and was negatively associated with measures of paretic arm motor function. Paretic iSP was longer compared with controls and negatively associated with clinical measures of manual dexterity. There was no relationship between coherence and. iSP for either group. No within- or between-group differences in coherence were observed at rest.

Conclusions. TMS-evoked cortical coherence during hand muscle activation can index interhemispheric interactions associated with poststroke motor function and potentially offer new insights into neural mechanisms influencing functional recovery.

 

via Role of Interhemispheric Cortical Interactions in Poststroke Motor Function – Jacqueline A. Palmer, Lewis A. Wheaton, Whitney A. Gray, Mary Alice Saltão da Silva, Steven L. Wolf, Michael R. Borich, 2019

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[WEB PAGE] The Use of Noninvasive Brain Stimulation, Specifically Transcranial Direct Current Stimulation After Stroke

Motor impairment is a leading cause of disability after stroke. Approaches such as noninvasive brain stimulation are being investigated to attempt to increase effectiveness of stroke rehabilitation interventions. There are several types of noninvasive brain stimulation: repetitive transcranial magnetic stimulation, transcranial direct stimulation (tDCS), transcranial alternative current stimulation, and transcranial pulsed ultrasound to name a few. Of the types of noninvasive brain stimulation, repetitive transcranial magnetic stimulation and tDCS have been most extensively tested to modulate brain activity and potentially behavior. These two techniques have distinctive modes of action. Repetitive transcranial magnetic stimulation directly stimulates neurons in the brain and, given the appropriate conditions, leads to new action potentials. On the other hand, tDCS polarizes neuronal tissue including neurons and glia modulating ongoing firing patterns. There are also differences in cost, utility, and knowledge skill required to apply tDCS and repetitive transcranial magnetic stimulation. Transcranial direct stimulation is relatively inexpensive, easy to administer, portable, and may be applied while undergoing therapy, with lasting excitability changes detectable up to 90 minutes after administration. Repetitive transcranial magnetic stimulation equipment is bulkier, expensive, technically more challenging, and a patient’s head must remain still when treatment is being applied therefore needs to be administered before or after a session of rehabilitation. Because of these differences, tDCS has been more accessible and has rapidly grew as a potential tool to be used in neurorehabilitation to facilitate retraining of activities of daily living (ADL) capacity and possibly to improve restoration of neurological function after stroke.

There are three current stimulation approaches using tDCS to modulate corticomotor regions after stroke. In anodal stimulation mode, the anode electrode is placed over the lesioned brain area and a reference electrode is applied over the contralateral orbitofrontal cortex. Anodal tDCS is placed over the ipsilesional hemisphere to improve the responses of perilesional areas to training protocols. In cathodal stimulation, the cathode electrode is placed over the nonlesioned brain area and reference electrode over the contralateral (ipsilesional) orbitofrontal cortex. This approach has been predicated on the hypothesis that the nonstroke hemisphere will be inhibited by tDCS resulting in an increased activation of the ipsilesional hemisphere due to rebalancing of a presumably abnormal interhemispheric interaction. Although some studies have shown this approach to be beneficial, the causative role of interhemispheric interaction imbalance has been recently challenged and refuted.1 Thus, if cathodal stimulation approaches are beneficial, the behavioral effect cannot be explained by a presumed correction of abnormal interhemispheric connectivity. Finally, dual tDCS approach involves simultaneous application of the anode over the ipsilesional and the cathode over the contralesional side. Here again, the intended mechanism of action is to rebalance the presumably abnormal interhemispheric interaction.

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CLINICAL QUESTIONS ADDRESSED

What is the best tDCS type and electrical configuration? What are the effects of tDCS with rehabilitation program for upper limb recovery after stroke?

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RESEARCH FINDINGS OF tDCS

This short article discusses data obtained from a network meta-analysis of randomized controlled trials and a recent meta-analysis. The network meta-analysis included 12 randomized controlled trials including 284 participants examining the effect of tDCS on ADL function in the acute, subacute, and chronic phases after stroke.2 The meta-analysis included 9 studies with 371 participants in any stage after stroke.3

The network meta-analysis found evidence of a significant moderate effect in favor of cathodal tDCS without significant effects of dual tDCS, anodal tDCS, or sham tDCS. There was no difference in safety (as assessed by dropouts and adverse events) between sham tDCS, physical rehabilitation, cathodal tDCS, dual tDCS, and anodal tDCS. Elsner in a previous review of tDCS in 2016 found an effect on improving ADL, as well as function of the arm and lower limb, muscle strength, and cognition. Thus, the findings from the most recent meta-analysis indicating cathodal that tDCS improves ADL capacity are in line with previous meta-analyses. Of note, there was no evidence of an effect of either cathodal or other tDCS stimulation approaches on upper paretic limb impairment after stroke as measured by the Fugl-Meyer scale.

A meta-analysis that included participants in any stage after the stroke showed that tDCS in conjunction with multiple sessions of rehabilitation had no significant effect over delivering therapy alone for upper limb impairment and activity after stroke. This negative finding might be due to patient’s being in an acute, subacute, or chronic stage after stroke as well as variations in the type of therapy performed paired with tDCS (ie, conventional vs. constraint-induced movement therapy vs. robot protocol).

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RECOMMENDATIONS FOR PHYSIATRIC PRACTICE

There seems to be a modest effect supporting the use of tDCS as a co-adjuvant of rehabilitation interventions to improve ADLs after stroke. Cathodal tDCS seems to be the most promising approach, especially when applied early after the stroke. However, the evidence remains preliminary and does not warrant a widespread change in clinical rehabilitation practice at this time.

There is no evidence supporting the use of tDCS to improve motor impairment (as measured by the FMS) at this point.

Importantly, tDCS remains as a very safe intervention, with no differences in safety when real vs. control tDCS is applied.

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REFERENCES

1. Xu J, Branscheidt M, Schambra H, et al: Rethinking interhemispheric imbalance as a target for stroke neurorehabilitation. Ann Neurol 2019;85:502–13

2. Elsner B, Kwakkel G, Kugler J, et al: Transcranial direct current stimulation (tDCS) for improving capacity in activities and arm function after stroke: a network meta-analysis of randomised controlled trials. J Neuroeng Rehabil 2017;14:

3. Tedesco Triccas L, Burridge J, Hughes A, et al: Multiple sessions of transcranial direct current stimulation and upper extremity rehabilitation in stroke: a review and meta-analysis. Clin Neurophysiol2016;127:946–55

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[ARTICLE] Searching for the optimal tDCS target for motor rehabilitation – Full Text

Abstract

Background

Transcranial direct current stimulation (tDCS) has been investigated over the years due to its short and also long-term effects on cortical excitability and neuroplasticity. Although its mechanisms to improve motor function are not fully understood, this technique has been suggested as an alternative therapeutic method for motor rehabilitation, especially those with motor function deficits. When applied to the primary motor cortex, tDCS has shown to improve motor function in healthy individuals, as well as in patients with neurological disorders. Based on its potential effects on motor recovery, identifying optimal targets for tDCS stimulation is essential to improve knowledge regarding neuromodulation as well as to advance the use of tDCS in clinical motor rehabilitation.

Methods and results

Therefore, this review discusses the existing evidence on the application of four different tDCS montages to promote and enhance motor rehabilitation: (1) anodal ipsilesional and cathodal contralesional primary motor cortex tDCS, (2) combination of central tDCS and peripheral electrical stimulation, (3) prefrontal tDCS montage and (4) cerebellar tDCS stimulation. Although there is a significant amount of data testing primary motor cortex tDCS for motor recovery, other targets and strategies have not been sufficiently tested. This review then presents the potential mechanisms and available evidence of these other tDCS strategies to promote motor recovery.

Conclusions

In spite of the large amount of data showing that tDCS is a promising adjuvant tool for motor rehabilitation, the diversity of parameters, associated with different characteristics of the clinical populations, has generated studies with heterogeneous methodologies and controversial results. The ideal montage for motor rehabilitation should be based on a patient-tailored approach that takes into account aspects related to the safety of the technique and the quality of the available evidence.

Introduction

Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique which delivers a constant electric current over the scalp to modulate cortical excitability [1,2,3]. Different montages of tDCS may induce diverse effects on brain networks, which are directly dependent on the electrodes positioning and polarity. While anodal tDCS is believed to enhance cortical excitability, cathodal tDCS diminishes the excitation of stimulated areas, and these electrodes montages define the polarity-specific effects of the stimulation [4,5,6]. Due to the effects of tDCS on modulating cortical excitability, especially when applied to the primary motor cortex [2], this method of brain stimulation has been intensively investigated for motor function improvement both in healthy subjects [78] and in various neurological pathologies [910]. Neurological conditions that may obtain benefits from the use of tDCS include Stroke [11,12,13,14], Parkinson’s disease [15], Multiple Sclerosis [1617], among others.

The mechanisms of action underlying the modulation of neuronal activity induced by tDCS are still not completely understood. However, studies have demonstrated that the electric current generated by tDCS interferes in the resting membrane potential of neuronal cells, which modulates spontaneous brain circuits activity [1,2,3]. Some studies have suggested that tDCS could have an effect on neuronal synapsis’ strength, altering the activity of NMDA and GABA receptors, thus triggering plasticity process, such as long-term potentiation (LTP) and long-term depression (LTD) [1819]. The long-term effects of tDCS are also thought to be associated to changes in protein synthesis and gene expression [2021]. Additionally, neuroimaging study showed blood flow changes following stimulation, which may be related to a direct effect of tDCS over blood flow, with an increase in oxygen supply on cortical areas and subsequent enhancement of neuronal excitability [22]. Given these mechanisms, tDCS seems to be a potential valuable tool to stimulate brain activity and plasticity following a brain damage.

The advantages of using tDCS include its low cost, ease of application, and safety. To date, there is no evidence of severe adverse events following tDCS in healthy individuals, as well as in patients with neurological conditions, such as stroke [2324]. Among the potential side effects presented after this type of stimulation, the most common ones consist of burn sensation, itching, transient skin irritation, tingling under the electrode, headache, and low intensity discomfort [25]. As serious and irreversible side effects have not been reported, tDCS is considered a relatively safe and tolerable strategy of non-invasive brain stimulation.

The modifications of physiological and clinical responses induced by tDCS are extremely variable, as this type of stimulation can induce both adaptive or maladaptive plastic changes, and a wide spectrum of tDCS parameters influence the effects of this technique. Electrodes combination, montage and shape can easily interfere in the enhancement or inhibition of cortical excitability [626]. Other parameters that may influence these outcomes include current intensity, current flow direction, skin preparation, and stimulation intervals [32728] . In addition, in clinical populations, the heterogeneity of the brain lesions can also influence the inconsistency in tDCS effects [29]. Despite the goal of tDCS of modulating cortical areas by using different parameters, some studies have showed that, by altering cortical excitability, the electrical field could reach subcortical structures, such as basal ganglia, due to brain connections between cortical and subcortical areas [30,31,32,33]. This potential effect on deeper brain structure has supported the broad investigation of tDCS in various disorders, even if the cortical region under stimulating electrode is not directly linked to the neurological condition being investigated. Indeed, the current variable and moderate effect sizes from clinical tDCS studies in stroke encourage researchers to test alternative targets to promote motor recovery in this condition.

In this review, we discuss evidence on the application of four different tDCS montages to promote and enhance motor rehabilitation: [1] anodal tDCS ipsilateral and cathodal tDCS bilateral, [2] combination of central and peripheral stimulation, [3] prefrontal montage and [4] cerebellar stimulation.[…]

 

Continue —> Searching for the optimal tDCS target for motor rehabilitation | Journal of NeuroEngineering and Rehabilitation | Full Text

figure1

Fig. 1 Motor cortex stimulation in a scenario where the left hemisphere was lesioned. Figure a Anodal stimulation of left primary motor cortex: anode over the left M1 and cathode over the right supraorbital region. Figure b Cathodal stimulation of right primary motor cortex: cathode over the right M1 and anode over the left supraorbital region. Figure c Bilateral stimulation: anode over the affected hemisphere (left) and cathode over the non-affected hemisphere (right)

 

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[Editorial] Introducing the thematic series on transcranial direct current stimulation (tDCS) for motor rehabilitation: on the way to optimal clinical use

Introduction

Transcranial direct current stimulation (tDCS) is a method of noninvasive brain stimulation that directs a constant low amplitude electric current through scalp electrodes. tDCS has been shown to modulate excitability in both cortical and subcortical brain areas [], with anodal tDCS leading to increased neuronal excitability and cathodal tDCS inversely leading to reduced neuronal excitability. tDCS can also modulate blood flow (i.e. oxygen supply to cortical and subcortical areas []) and neuronal synapsis strength [], triggering plasticity processes (i.e. long-term potentiation and long-term depression). There is growing interest in using tDCS as a low-cost, non-invasive brain stimulation option for a wide range of potential clinical applications. Advantages of tDCS over other methods of non-invasive brain stimulation include favorable safety and tolerability profiles and its portability and applicability.

The use of tDCS in motor rehabilitation for neurological diseases as well as in healthy ageing is a growing area of therapeutic use. Although the results of tDCS interventions for motor rehabilitation are still preliminary, they encourage further research to better understand its therapeutic utility and to inform optimal clinical use. Therefore, The Journal of NeuroEngineering and Rehabilitation (JNER. https://jneuroengrehab.biomedcentral.com/) is pleased to present the thematic series entitled “tDCS application for motor rehabilitation”.

The goal of this thematic series is to increase the awareness of academic and clinical communities to different potential applications of tDCS for motor rehabilitation. Experts in the field were invited to submit experimental or review studies. A call for papers was also announced to reach those interested in contributing to this thematic series. This collection of articles was thought to present the most recent advances in tDCS for motor rehabilitation, addressing topics such as theoretical, methodological, and practical approaches to be considered when designing tDCS-based rehabilitation. The targeted disorders include but are not limited to: stroke, Parkinson’s disease, Cerebral Palsy, cerebellar ataxia, trauma, Multiple Sclerosis.

tDCS – A promising clinical tool for motor rehabilitation

tDCS has been used in experimental and clinical neuroscience for the study of brain functions and treatment in a range of disorders of the central nervous system. Of particular interest to this thematic series, a growing body of evidence suggest that tDCS has potential to become a clinical tool for motor rehabilitation.

The existing tDCS protocols using well-defined montages, stimulus durations and intensities are safe and well tolerated by both healthy individuals and clinical populations. There are no reported indications of any serious adverse effects, such as damage of brain tissue or seizure induction, with the use of 1–2 mA protocols []. The most commonly reported adverse effects included redness, tingling and itching sensations under the electrodes, as well as headache []. Moreover, the overall adverse effect rates are similar between active and sham tDCS [], which suggests that the mild adverse effects are related to electrode positioning on the skin and not the stimulation itself.

As tDCS is portable, devices can easily be transported, which circumvents accessibility barriers to health care (i.e. tDCS can easily be moved into clinics or wards). It can be implemented in combination with other kinds of interventions, such as cognitive or physical training or exercise, with this pairing possibly leading to synergistic benefit []. Although accumulating evidence highlights potential benefits offered by tDCS for motor rehabilitation, further research is required for tDCS to become an approved clinical tool. The majority of existing clinical trials has involved a limited number of participants, which may imply underpowered analysis. Thus, large-scale studies are needed to overcome this major flaw.

Due to the potential for self- or caregiver-application, remotely supervised protocols have been developed and recently found feasible for those with motor impairment []. However, these studies employ highly structured protocols and rigorous criteria with real time supervision via teleconference, and do not support a “do-it-yourself” tDCS practice. Instead, the remotely supervised protocols can be used to facilitate the clinical trial designs that are necessary in order to advance tDCS towards therapeutic use.

Data on optimal protocols and predictors of response to tDCS are currently lacking in the literature. Future studies in this field should focus on determining the optimal stimulation parameters and predictors of response to tDCS in different clinical populations. It seems that one size does not fit all in tDCS. However, previous studies may be limited, as standard clinical assessments may miss subtle motor improvements. Future outcomes for determining the effectiveness of tDCS for motor rehabilitation need to be robust. Therefore, combining tDCS protocols with other validated mobile technologies to monitor motor performance, such as wearable inertial sensors or innovative Internet of Things devices, may provide important insight into effectiveness within clinic and beyond.

Despite the positive progression of research to clinical practice, there are still questions to be answered before tDCS can be extensively recommended for motor rehabilitation.

• What is the ideal intensity and duration of the session?

• How many sessions are required?

• What is the ideal interval between sessions?

• What about patients’ characteristics?

• Who will benefit from tDCS?

• Do specific demographic characteristics lead to greater benefits?

Final considerations

We hope the accepted papers will contribute meaningfully to the body of knowledge in the field of tDCS for motor rehabilitation and that they will motivate the development of further research. Additionally, we hope this thematic series will assist both researchers and clinical professionals in making decisions for the achievement of optimal benefits throughout tDCS.

References

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    Bolzoni F, Pettersson L-G, Jankowska E. Evidence for long-lasting subcortical facilitation by transcranial direct current stimulation in the cat. J Physiol [Internet]. 2013 [cited 2018 Nov 10];591:3381–3399. Available from: http://doi.wiley.com/10.1113/jphysiol.2012.244764.
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    Nitsche MA, Paulus W. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol [Internet]. 2000 [cited 2018 Nov 10];527 Pt 3:633–639. Available from: http://www.ncbi.nlm.nih.gov/pubmed/10990547.
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    Zheng X, Alsop DC, Schlaug G. Effects of transcranial direct current stimulation (tDCS) on human regional cerebral blood flow. Neuroimage [Internet]. 2011 [cited 2019 Feb 14];58:26–33. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21703350.
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    Polanía R, Paulus W, Antal A, Nitsche MA. Introducing graph theory to track for neuroplastic alterations in the resting human brain: a transcranial direct current stimulation study. Neuroimage [Internet]. 2011 [cited 2019 Feb 14];54:2287–2296. Available from: https://linkinghub.elsevier.com/retrieve/pii/S1053811910012875.
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    Woods AJ, Antal A, Bikson M, Boggio PS, Brunoni AR, Celnik P, et al. A technical guide to tDCS, and related non-invasive brain stimulation tools. Clin Neurophysiol [Internet] 2016 [cited 2018 Nov 10];127:1031–1048. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26652115.
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    Moffa AH, Brunoni AR, Fregni F, Palm U, Padberg F, Blumberger DM, et al. Safety and acceptability of transcranial direct current stimulation for the acute treatment of major depressive episodes: Analysis of individual patient data. J Affect Disord [Internet]. 2017 [cited 2018 Nov 10];221:1–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28623732.
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    Bikson M, Grossman P, Thomas C, Zannou AL, Jiang J, Adnan T, et al. Safety of transcranial direct current stimulation: evidence based update 2016. Brain Stimul [Internet] 2016 [cited 2018 Nov 10];9:641–661. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27372845.
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    Fertonani A, Ferrari C, Miniussi C. What do you feel if I apply transcranial electric stimulation? Safety, sensations and secondary induced effects. Clin Neurophysiol [Internet]. 2015 [cited 2018 Nov 10];126:2181–2188. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25922128.
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    Kaski D, Dominguez R, Allum J, Islam A, Bronstein A. Combining physical training with transcranial direct current stimulation to improve gait in Parkinson’s disease: a pilot randomized controlled study. Clin Rehabil [Internet]. 2014 [cited 2018 Nov 10];28:1115–24. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24849794.
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    Agarwal S, Pawlak N, Cucca A, Sharma K, Dobbs B, Shaw M, et al. Remotely-supervised transcranial direct current stimulation paired with cognitive training in Parkinson’s disease: An open-label study. J Clin Neurosci [Internet]. 2018 [cited 2018 Nov 10];57:51–57. Available from: http://www.ncbi.nlm.nih.gov/pubmed/30193898.

via Introducing the thematic series on transcranial direct current stimulation (tDCS) for motor rehabilitation: on the way to optimal clinical use | SpringerLink

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[ARTICLE] A review of transcranial electrical stimulation methods in stroke rehabilitation – Full Text

 

Abstract

Transcranial electrical stimulation (TES) uses direct or alternating current to non-invasively stimulate the brain. Neuronal activity in the brain is modulated by the electrical field according to the polarity of the current being applied. TES includes transcranial direct current stimulation (tDCS), transcranial random noise stimulation, and transcranial alternating current stimulation (tACS). tDCS and tACS are the two non-invasive brain stimulation techniques that have been used alone or in combination with other rehabilitative therapies for the improvement of motor control in hemiparesis. Increasing research in these methods is being carried out to improvise on the existing technology because they have proven to exhibit a lasting effect, thereby contributing to brain plasticity and motor re-learning. Artificial stimulation of the lesioned or non-lesioned hemisphere induces participation of its cells when a movement is being performed. The devices are portable, stimulation is easy to deliver, and they are not known to cause any major side effects which are the foremost reasons for their trials in stroke rehabilitation. Recent research is focused on maximizing the outcome of stroke rehabilitation by combining them with other modalities. This review focuses on stimulation protocols, parameters, and the results obtained by these techniques and their combinations.

Key Message: Motor recovery and control poses a great challenge in stroke rehabilitation. Transcranial electrical stimulation methods look promising in this regard as they have been shown to augment long-term and short-term potentiation in the brain which may have a role in motor re-learning. This review discusses transcranial direct current stimulation and transcranial alternating current stimulation in stroke rehabilitation.

According to World Health Organization (WHO) statistics on 2016, cardiovascular diseases (CVD) are the foremost cause of death and adult disability worldwide.[1],[2] Stroke statistics in India show that the incidence of stroke was 435/100,000 population and only one in three stroke survivors are hospitalized and given further rehabilitation because treatment is expensive.[3]

Stroke survivors are faced with paralysis of one side of the body, that is, the side contra-lateral to the affected side in the brain. Rehabilitation aims at strengthening these muscles to prevent wastage and bring back function to the maximum possible extent. Taking the upper extremity into consideration, a combination of muscle over-activity (spastic muscle) in certain groups and weakening in other groups causes poor motor control leading to deformities and inability to reach, grasp, and release objects.

Various therapies such as splinting, stretching exercises, functional electrical stimulation (FES), and mirror therapy are being used to treat this condition, with varying degrees of success. In an ideal situation, the aim of stroke rehabilitation is to recover the paralyzed limb to an extent that it is functionally useful. In this context, recent research is being conducted in neuroplasticity or motor-relearning. Neuroplasticity refers to the brain being able to adapt to changes in response to its external environment and stimulation. TES and transcranial magnetic stimulation (TMS) are the non-invasive brain stimulation (NIBS) methods that invoke this type of re-learning.[4],[5]

NIBS methods include TMS and TES since they non-invasively stimulate the cortex. These methods are still under research for medical applications and were first introduced to treat psychiatric conditions such as insomnia, chronic anxiety, mild depression and post stroke aphasia.[6],[7],[8] Recently, tDCS has also been tried on normal individuals and was shown to improve cognition, working memory, and performance.[9],[10],[11] These methods are now gaining importance in stroke rehabilitation because they provide motor relearning probably through cortical reorganization, which occurs because the neural continuity between the brain and the periphery is intact.[12]

This article attempts to review the stimulation protocols used for TES by various research groups and the results obtained. The first section begins with an introduction to non-invasive methods of brain stimulation followed by a brief summary on the history that led to the use of TES for stroke rehabilitation. Later sections deal with tDCS and tACS. The section on tDCS is further subdivided into tDCS alone and tDCS with adjuvant therapy. The tables give a list of the studies that have been carried out for neurorehabilitation, although it is not meant to be an exhaustive list.[…]

Continue —> A review of transcranial electrical stimulation methods in stroke rehabilitation Solomons CD, Shanmugasundaram V Neurol India

Figure 1: Placement of electrodes for a-tDCS and c-tDCS

Figure 1: Placement of electrodes for a-tDCS and c-tDCS

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