At Neuroelectrics, we believe in the advantages and effectiveness of transcranial electric stimulation (tES) in treating numerous brain diseases. Yet, despite the increasing number of tES publications per year, the lion’s share in the market of non-invasive brain stimulation technologies is still played by transcranial magnetic stimulation (TMS), likely because TMS received US-FDA approval in 2008 whereas tES has not yet.
Does this mean TMS is more effective? Well, it’s not quite fair to say so, considering TMS studies started at least 10 years earlier than those of tES. Therefore, there are several more clinical trials proving TMS efficacy.
However, the two techniques are close relatives: you can think of TMS as the elderly, stiff and sturdy brother, and tES as the younger, more flexible and easy-going one.
In this blogpost, we’ll go over the roots of their differences and see when and why you might prefer one over the other.
[E-fields patterns and biophysical substrates]
At a fundamental level, the two techniques rely on different physics and induce distinct patterns of electric fields (E-field) on the cortex, acting on a different neural substrate.
TMS is based on electromagnetic induction: a large magnetic coil is placed just a few centimetres above the scalp to stimulate over a specific cortical area. When the operator launches the electric pulse, vast amounts of current flows suddenly through the coil and creates a magnetic field around it, which varies rapidly in time. This changing magnetic field induces a very short (order of 1ms), highly localized (figure 1), super-threshold (order of 100V/m) E-field in the cortex. The E-field maximum is reached on the gyrus right under the coil, and the orientation is mostly parallel to the cortical surface.
The most sensitive cells to an E-field with such characteristics are interneurons and collaterals of pyramidal cells aligned tangentially to the cortical surface, which are automatically triggered to fire.
Instead, tES operates in the (quasi-)static regime, as only a small amount of direct current (DC) or low frequency alternating current (AC) is applied through electrodes placed directly on the scalp. The temporal resolution of the technique is low because the neuromodulatory effects begins a few seconds after the start of stimulation. Moreover, the E-field generated is much weaker (order of 0.1V/m) and less focalized (although the focality can be improved by using multichannel montages, it remains much lower than TMS E-field). Depending on the electrodes’ geometry, the maxima can occur on the gyri at the edges of the electrodes or between them. The overall orientation of the E-field is normal to the cortical surface, which indicates that tES probably influences layer V pyramidal neurons, as they are mostly perpendicular to the cortex.
Given the low, subthreshold intensity, the tES E-field cannot cause neural firing, but it is able to modulate the firing rate, facilitating or inhibiting the activation of pyramidal cells.
Other important differences concerning system setup.
TMS technology is more complex and cumbersome. The cost of the whole equipment is between 50-100k USD or Euros. This includes a wall-powered and heavy stimulator about the size of a fridge, a coil connected to the stimulator by a high-voltage cable, a mechanical arm to hold it in place, and a neuro-navigation system to accurately place the coil over the target brain region. The coil hangs suspended over the head of the patient, and since the strength of the effects depends on the coil-cortex distance, it’s crucial to keep it at the specific distance. For this, during the treatment session, the patient must sit still in a specially designed chair, with positioning frames around the chin and forehead.
On the contrary, tES is much cheaper and effortless: the cost is between an average of 6-30k USD/Euros, and the whole setup fits a shoe box. The stimulator can be as small as a mobile phone, light/portable, and almost always battery powered. The electrodes are directly in contact with the scalp, held in place by a rubber band or a neoprene cap. This way, the patient can move and even walk during the stimulation session.
Despite the underlying differences, TMS and tES are both quite versatile tools for treatment and research, and they offer similar options.
In research settings, you can leverage on TMS’ high spatial and temporal resolution to study how brain networks dynamically operate. In this context, TMS is usually performed online (during task performance) by applying one pulse at the onset of a stimulus (single-pulse TMS), or two pulses over separate regions which are interconnected (paired-pulses TMS). But tES too allows one to study the causal link between cortical areas. For instance, with tACS, one can simultaneously apply oscillatory currents over distinct regions at the same frequency but with different phases to promote or hamper the synchronization of functional networks.
Clinical applications of brain stimulation techniques instead tend to focus more on long-term effects, promoting network neuroplasticity that can outlast the period of stimulation.
In this case, TMS is usually ran in the repetitive mode (rTMS), which consists in multiple pulses within just microseconds. Frequency lower than 1Hz has been linked to long term depression (LTD), whereas frequency above 5Hz to long term potentiation (LTP). Similar outcomes can be achieved with tCS using either tDCS anodal or cathodal stimulation, which has been shown promoting and inhibiting synaptic activation, respectively.
The side effects of both techniques are quite moderate – with one important exception. While tES can induce only mild and temporary itching, tingling, and skin reddening when done properly, TMS might cause mild headaches, facial twitching, seizures in extreme cases.
For both TMS and tES, medical treatment must be performed mostly in clinical settings, which means you will have to find a clinician who provides these services in their clinic. However, one of the strengths of tES is the possibility to perform stimulation telemedically (under the remote guidance of a clinicians) via home-treatment. This is important as it will boost therapeutic effects for pathologies such as motor rehabilitation, depression, Alzheimer’s disease, etc in the comfort of one’s home. And it has been shown that the number of sessions modulates the length of the long-term plastic effects.
Interested in home-application of tCS? Check our home-kit here.
Polanía R, Nitsche M.A., Ruff C., Studying and modifying brain function with non-invasive brain stimulation, Nat. neurosci., 21:174–187 (2018)
Dayan E., Censor N., Buch E.R., Sandrini M, Cohen L.G., Noninvasive brain stimulation: from physiology to network dynamics and back, Nat. Neurosci., 16:838–844 (2013)
Salvador R., Wenger C., Miranda P.C. Investigating the cortical regions involved in MEP modulation in tDCS, Front. Cell. Neurosci. 9:405 (2015)
Transcranial direct current stimulation (tDCS) is a treatment used in the rehabilitation of stroke patients aiming to improve functionality of the plegic upper extremity. Currently, tDCS is not routinely used in post stroke rehabilitation. The aim of this study was to establish the effects of bihemspheric tDCS combined with physical therapy (PT) and occupational therapy (OT) on upper extremity motor function.
Thirty-two stroke inpatients were randomised into 2 groups. All patients received 15 sessions of conventional upper extremity PT and OT over 3 weeks. The tDCS group (n = 16) also received 30 minutes of bihemispheric tDCS and the sham group (n = 16) 30 minutes of sham bihemispheric tDCS simultaneously to OT. Patients were evaluated before and after treatment using the Fugl Meyer upper extremity (FMUE), functional independence measure (FIM), and Brunnstrom stages of stroke recovery (BSSR) by a physiatrist blind to the treatment group
The improvement in FIM was higher in the tDCS group compared to the sham group (P = .001). There was a significant within group improvement in FMUE, FIM and BSSR in those receiving tDCS (P = .001). There was a significant improvement in FIM in the chronic (> 6months) stroke sufferers who received tDCS when compared to those who received sham tDCS and when compared to subacute stroke (3-6 months) sufferers who received tDCS/sham.
Upper extremity motor function in hemiplegic stroke patients improves when bihemispheric tDCS is used alongside conventional PT and OT. The improvement in functionality is greater in chronic stroke patients.
Neuromodulation is the use of electrical, magnetic, or chemical stimulation to modulate nervous tissue function. Research studies with promising results from novel treatments using neuromodulations are emerging.
On October 4, 2019, a study published in the American Journal of Psychiatry, led by Professor Helen S. Mayberg, M.D. at the Icahn School of Medicine at Mount Sinai and Dr. Andrea Crowell at Emory University, showed that deep brain stimulation for treatment-resistant depression for a majority of the participants had a “robust and sustained antidepressant response” in an over eight-year period, and there were not any suicides.
Earlier this year, in April, Boston University scientists Robert M. G. Reinhart and John A. Nguyen published in Nature Neuroscience a neuromodulation study that demonstrated noninvasive electrical brain stimulation temporarily improved the working memory accuracy in older adults. The study used 84 people—half between the ages of 20-29, and the other half between 60-76 years old.
The scientists hypothesize that their technique improved behavior due to neuroplastic changes in functional connectivity for up to 50 minutes afterward. Additional studies with more test subjects are needed to test the hypothesis and determine the full course potential of the effects.
These are just a few examples of the numerous research studies in neuromodulation. Neuromodulation methods include optogenetics, cochlear implants, retinal implants, deep brain and spinal cord stimulators, pharmacotherapy, and electroceuticals. Potential applications for neuromodulation may include chronic pain management, Alzheimer’s disease, depression, complications due to stroke, traumatic brain injuries, Parkinson’s disease, epilepsy, migraines, spinal cord injuries, and other conditions. Currently, there are over 590 neuromodulation clinical studies worldwide, according to the U.S. National Institute of Health’s Library of Medicine database of privately and publicly funded clinical studies conducted around the world.
Within the growing neuromodulation market, one segment, transcranial direct current stimulation (tDCS), is moving beyond health care and is making inroads into the consumer segment. Transcranial direct current stimulation is a form of noninvasive brain stimulation using a constant weak electrical current. Typically the voltage is less than two milliamps.
One of the earliest records of transcranial direct current stimulation dates to the ancient Roman Empire. The physician to Roman Emperor Tiberius Claudius Nero Caesar, Scribonius Largus, put a live torpedo fish, an electric ray capable of delivering up to 220 volts, directly on a patient in an effort to use the animal’s electrical discharges for pain therapy.
Fast forward to present day, and transcranial direct current stimulation is being used for a variety of purposes as an emerging technology for neuroscientists, elite athletes, e-sports gamers, neurologists, musicians, and psychiatrists—sans the torpedo fish. Instead, electronic devices in various form-factors are used to deliver currents to the human brain noninvasively via the scalp. Consumer-based transcranial direct current stimulation devices operate on the principle of neuroplasticity—the brain’s ability to change neural connections and behavior.
“Neuroplasticity is the property of the brain that enables it to change its own structure and functioning in response to activity and mental experience,” wrote the New York Times bestselling author, psychiatrist, and psychoanalyst, Norman Doidge, FRCPC, in his 2015 book The Brain’s Way of Healing: Remarkable Discoveries and Recoveries from the Frontiers of Neuroplasticity.
An example of a consumer-based transcranial direct current stimulation device is the Halo Sport 2, a wireless headset introduced in January 2019 that stimulates the brain’s motor cortex through electrical currents to create a temporary state of neuroplasticity. Whether the activity is learning music, dance, or sports, the human brain learns movement via the motor cortex.
The device is made by venture-backed startup Halo Neuroscience, a company founded in 2013 by Daniel Chao, Brett Wingeier, Lee von Kraus, Ph.D., and Amol Sarva, with investments from Jazz Venture Partners, Lux Capital, TPG, Andreessen Horowitz, and others. To use the Halo Sport 2 is simple—neuroprime with the headset on for 20 minutes, then train for an hour afterward.
Halo Sport users include athletes, musicians, and the military—such as members of Major League Baseball’s San Francisco Giants, National Basketball Association’s Golden State Warriors, the U.S. Navy SEALs, USA Cycling, the United States Ski Team, Berklee College of Music, Invictus, as well as many others.
World champion triathlete Timothy O’Donnell is a Halo Sport user. O’Donnell has over 50 podium finishes, including 22 wins. He won two IRONMAN titles, six Armed Forces National Championships, nine Ironman 70.3 races, an ITU Long Distance World Champion race, and many other prestigious competitive triathlon medals. As a world-class elite athlete, O’Donnell is constantly seeking innovative ways to improve his performance. He reportedly reached out to Halo Neuroscience after reading about the technology and incorporates Halo Sport neuropriming in his training to give him an edge.
A number of investments in neuroscience companies have emerged in recent years, such as Bryan Johnson’s Kernel, Elon Musk’s Neuralink, and Tej Tadi’s MindMaze. Other neurotechnology startups include Synchron, founded by Nicholas Opie and Thomas Oxley, BIOS founded by Emil Hewage and Oliver Armitage, BrainCo founded by Bicheng Han, Nextmind founded by Gwendal Kerdavid and Sid Kouider, Thync founded by Isy Goldwasser and Jamie Tyler, EMOTIV founded by Tan Le and Dr. Geoff Mackellar, Paradromics founded by Matt Angle, Bitbrain founded by Javier Minguez Zafra and Maria Lopez Valdes, Flow Neuroscience founded by Daniel Månsson and Erik Rehn, Dreem founded by Hugo Mercier and Quentin Soulet de Brugière, Neuros Medical founded by Jon J. Snyder, Neurable founded by James Hamet, Michael Thompson and Ramses Alcaide, Cognixion founded by Andeas Forsland, Q30 Innovations founded by Bruce Angus and Thomas Hoey, Neuroscouting founded by Dr. Wesley Clapp and Dr. Brian Miller, and Meltin MMI founded by Masahiro Kasuya, and Neuropace founded by David R. Fischell.
The global neuromodulation device industry is expected to increase to 13.3 billion by 2022, according to Neurotech Reports figures published in September 2018. Within this growing space, consumer-based transcranial direct current stimulation is an emerging market to watch.
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.
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.
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.
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.
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.
Difficulty to walk is a key feature of neurological disorders , so much so that recovering and/or maintaining the patient’s walking ability has become one of the main aims of all neurorehabilitation programs . Additionally, the loss of this ability is one of the most significant factors negatively impacting on the social and professional reintegration of neurological patients .
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 . 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 .
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 .
The effectiveness of tDCS has been proven for treating certain pathologies such as depression, addictions, fibromyalgia, or chronic pain . Also, tDCS has shown to improve precision and motor learning  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 [12, 13]. 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 . In terms of gait rehabilitation, current studies are scarce and controversial .
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  or muscle strengthening to increase functionality in patients suffering from knee osteoarthritis . 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. […]
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.
Allman, C., Amadi, U., Winkler, A.M., Wilkins, L., Filippini, N., Kischka, U., Stagg, C.J., and Johansen-Berg, H. (2016). Ipsilesional anodal tDCS enhances the functional benefits of rehabilitation in patients after stroke. Sci. Transl. Med. 8, 330re1.PubMedCrossrefGoogle Scholar
Ameli, M., Grefkes, C., Kemper, F., Riegg, F.P., Rehme, A.K., Karbe, H., Fink, G.R., and Nowak, D.A. (2009). Differential effects of high-frequency repetitive transcranial magnetic stimulation over ipsilesional primary motor cortex in cortical and subcortical middle cerebral artery stroke. Ann. Neurol. 66, 298–309.PubMedCrossrefGoogle Scholar
Andrade, S.M., Batista, L.M., Nogueira, L.L., de Oliveira, E.A., de Carvalho, A.G., Lima, S.S., Santana, J.R., de Lima, E.C., and Fernández-Calvo, B. (2017a). Constraint-induced movement therapy combined with transcranial direct current stimulation over premotor cortex improves motor function in severe stroke: a pilot randomized controlled trial. Rehab. Res. Pract. 2017, 6842549.Google Scholar
Andrade, S.M., Ferreira, J.J.A., Rufino, T.S., Medeiros, G., Brito, J.D., da Silva, M.A., and Moreira, R.N. (2017b). Effects of different montages of transcranial direct current stimulation on the risk of falls and lower limb function after stroke. Neurol. Res. 39, 1037–1043.CrossrefGoogle Scholar
Bikson, M., Grossman, P., Thomas, C., Zannou, A.L., Jiang, J., Adnan, T., Mourdoukoutas, A.P., Kronberg, G., Truong, D., Boggio, P., et al. (2016). Safety of transcranial direct current stimulation: evidence based update 2016. Brain Stimul. 9, 641–661.CrossrefPubMedGoogle Scholar
Bolognini, N. and Vallar, G. (2015). Stimolare il cervello. Manuale di stimolazione cerebrale non invasiva (pp. 1–224). il Mulino.Google Scholar
Bolognini, N., Pascual-Leone, A., and Fregni, F. (2009). Using non-invasive brain stimulation to augment motor training-induced plasticity. J. Neuroeng. Rehab. 6, 8.CrossrefGoogle Scholar
Bolognini, N., Vallar, G., Casati, C., Latif, L.A., El-Nazer, R., Williams, J., Banco, E., Macea, D.D., Tesio, L., Chessa, C., et al. (2011). Neurophysiological and behavioral effects of tDC combined with constraint-induced movement therapy in post stroke patients. Neurorehab. Neural Rep. 25, 819–829.CrossrefGoogle Scholar
Bortoletto, M., Rodella, C., Salvador, R., Miranda, P.C., and Miniussi, C. (2016). Reduced current spread by concentric electrodes in transcranial electrical stimulation (tES). Brain Stimul. 9, 525–528.CrossrefPubMedGoogle Scholar
Bradnam, L.V., Stinear, C.M., Barber, P.A., and Byblow, W.D. (2012). Contralesional hemisphere control of the proximal paretic upper limb following stroke. Cereb. Cortex 22, 2662–2671.PubMedCrossrefGoogle Scholar
Brunelin, J., Mondino, M., Gassab, L., Haesebaert, F., Gaha, L., Suaud-Chagny, M.F., Saoud, M., Mechri, A., and Poulet, E. (2012a). Examining transcranial direct current stimulation (tDCS) as a treatment for hallucinations in schizophrenia. Am. J. Psychiatry 169, 719–724.CrossrefGoogle Scholar
Brunoni, A.R., Zanao, T.A., Ferrucci, R., Priori, A., Valiengo, L., de Oliveira, J.F., Boggio, P.S., Lotufo, P.A., Benseñor, I.M., and Fregni, F. (2013c). Bifrontal tDCS prevents implicit learning acquisition in antidepressant-free patients with major depressive disorder. Prog. Neuro-Psychopharmacol. Biol. Psychiatry 43, 146–150.CrossrefGoogle Scholar
Burke Quinlan, E., Dodakian, L., See, J., McKenzie, A., Le, V., Wojnowicz, M., Shahbaba, B., and Cramer, S.C. (2015). Neural function, injury, and stroke subtype predict treatment gains after stroke. Ann. Neurol. 77, 132–145.CrossrefPubMedGoogle Scholar
Byblow, W.D., Stinear, C.M., Barber, P.A., Petoe, M.A., and Ackerley, S.J. (2015). Proportional recovery after stroke depends on corticomotor integrity. Ann. Neurol. 78, 848–859.CrossrefPubMedGoogle Scholar
Chang, M.C., Kim, D.Y., and Park, D.H. (2015). Enhancement of cortical excitability and lower limb motor function in patients with stroke by transcranial direct current stimulation. Brain Stimul. 8, 561–566.CrossrefPubMedGoogle Scholar
Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences. 2nd ed. (Hillsdale, NJ: Erlbaum).Google Scholar
Coin, A., Najjar, M., Catanzaro, S., Orru, G., Sampietro, S., Sergi, G., Manzato, E., Perissinotto, E., Rinaldi, G., Sarti, S., et al. (2009). A retrospective pilot study on the development of cognitive, behavioral and functional disorders in a sample of patients with early dementia of Alzheimer type. Arch. Gerontol. Geriatr. 49, 35–38.CrossrefGoogle Scholar
Conti, C.L. and Nakamura-Palacios, E.M. (2013). Bilateral transcranial direct current stimulation over dorsolateral prefrontal cortex changes the drug-cued reactivity in the anterior cingulate cortex of crack-cocaine addicts. Brain Stimul. 7, 130–132.PubMedGoogle Scholar
Da Costa Santos, C.M., de Mattos Pimenta, C.A., and Nobre, M.R. (2007). The PICO strategy for the research question construction and evidence search. Rev. Lat. Am. Enfermagem. 15, 508–511.PubMedCrossrefGoogle Scholar
De Vries, M.H., Barth, A.C., Maiworm, S., Knecht, S., Zwitserlood, P., and Flöel, A. (2010). Electrical stimulation of Broca’s area enhances implicit learning of an artificial grammar. J. Cognit. Neurosci. 22, 2427–2436.CrossrefGoogle Scholar
Di Lazzaro, V., Dileone, M., Capone, F., Pellegrino, G., Ranieri, F., Musumeci, G., Florio, L., Di Pino, G., and Fregni, F. (2014). Immediate and late modulation of interhemispheric imbalance with bilateral transcranial direct current stimulation in acute stroke. Brain Stimul. 7, 841–848.CrossrefGoogle Scholar
Feng, W., Wang, J., Chhatbar, P.Y., Doughty, C., Landsittel, D., Lioutas, V.A., and Schlaug, G. (2015). Corticospinal tract lesion load: an imaging biomarker for stroke motor outcomes. Ann. Neurol. 78, 860–870.CrossrefPubMedGoogle Scholar
Ferrucci, R., Mameli, F., Guidi, I., Mrakic-Sposta, S., Vergari, M., Marceglia, S., Cogiamanian, F., Barbieri, S., Scarpini, E., and Priori, A. (2008). Transcranial direct current stimulation improves recognition memory in Alzheimer disease. Neurology 71, 493–498.CrossrefPubMedGoogle Scholar
Figlewski, K., Blicher, J.U., Mortensen, J., Severinsen, K.E., Nielsen, J.F., and Andersen, H. (2017). Transcranial direct current stimulation potentiates improvements in functional ability in patients with chronic stroke receiving constraint-induced movement therapy. Stroke 48, 229–232.PubMedCrossrefGoogle Scholar
Fregni, F., Boggio, P.S., Nitsche, M., Bermpohl, F., Antal, A., Feredoes, E., Marcolin, M.A., Rigonatt, S.P., Silva, M.T., and Pascual-Leone, A. (2005). Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory. Exp. Brain Res. 166, 23–30.PubMedCrossrefGoogle Scholar
Fregni, F., Boggio, P.S., Lima, M.C., Ferreira, M.J., Wagner, T., Rigonatti, S.P., Castro, A.W., Souza, D.R., Riberto, M., Freedman, S.D., et al. (2006a). A sham controlled, phase II trial of transcranial direct current stimulation for the treatment of central pain in traumatic spinal cord injury. Pain 122, 197–209.CrossrefGoogle Scholar
Fregni, F., Boggio, P.S., Santos, M.C., Lima, M., Vieira, A.L., Rigonatti, S.P., Silva, M.T., Barbosa, E.R., Nitsche, M.A., and Pascual-Leone, A. (2006b). Non invasive cortical stimulation with transcranial direct current stimulation in Parkinson’s disease. Mov. Disord. 21, 1693–1702.CrossrefGoogle Scholar
Fregni, F., Gimenes, R., Valle, A.C., Ferreira, M.J., Rocha, R.R., Natalle, L., Bravo, R., Rigonatti, S.P., Freedman, S.D., Nitsche, M.A., et al. (2006c). A randomized, sham-controlled, proof of principle study of transcranial direct current stimulation for the treatment of pain in fibromyalgia. Arthritis Rheum 54, 3988–3998.CrossrefGoogle Scholar
Fusco, A., Assenza, F., Iosa, M., Izzo, S., Altavilla, R., Paolucci, S., and Vernieri, F. (2014). The ineffective role of cathodal tDCS in enhancing the functional motor outcomes in early phase of stroke rehabilitation: an experimental trial. BioMed Res. Int. 2014, 547290.PubMedGoogle Scholar
Geroin, C., Picelli, A., Munari, D., Waldner, A., Tomelleri, C., and Smania, N. (2011). Combined transcranial direct current stimulation and robot-assisted gait training in patients with chronic stroke: a preliminary comparison. Clin. Rehabil. 25, 537–548.PubMedCrossrefGoogle Scholar
Gladwin, T.E., den Uyl, T.E., Fregni, F.F., and Wiers, R.W. (2012). Enhancement of selective attention by tDCS: interaction with interference in a Sternberg task. Neurosci. Lett. 512, 33–37.CrossrefGoogle Scholar
Grefkes, C. and Fink, G.R. (2014). Connectivity-based approaches in stroke and recovery of function. Lancet Neurol. 13, 206–216.CrossrefPubMedGoogle Scholar
Hamoudi, M., Schambra, H.M., Fritsch, B., Schoechlin-Marx, A., Weiller, C., Cohen, L.G., and Reis, J. (2018). Transcranial direct current stimulation enhances motor skill learning but not generalization in chronic stroke. Neurorehabil. Neural Repair 32, 295–308.PubMedCrossrefGoogle Scholar
Hattie, J. (2009). Visible Learning: A Synthesis of Over 800 Meta-analyses Relating to Achievement (Park Square, Oxford: Rutledge).Google Scholar
Herrmann, C.S., Rach, S., Neuling, T., and Strüber, D. (2013). Transcranial alternating current stimulation: a review of the underlying mechanisms and modulation of cognitive processes. Front. Hum. Neurosci. 7, 279.PubMedGoogle Scholar
Hesse, S., Waldner, A., Mehrholz, J., Tomelleri, C., Pohl, M., and Werner, C. (2011). Combined transcranial direct current stimulation and robot-assisted arm training in subacute stroke patients: an exploratory, randomized multicenter trial. Neurorehabil. Neural Repair 25, 838–846.PubMedCrossrefGoogle Scholar
Holman, L., Head, M.L., Lanfear, R., and Jennions, M.D. (2015). Evidence of experimental bias in the life sciences: why we need blind data recording. PLoS Biol. 13, e1002190.CrossrefPubMedGoogle Scholar
Horn, S.D., DeJong, G., Smout, R.J., Gassaway, J., James, R., and Conroy, B. (2005). Stroke rehabilitation patients, practice, and outcomes: is earlier and more aggressive therapy better? Arch. Phys. Med. Rehab. 86, 101–114.CrossrefGoogle Scholar
Horvath, J.C., Forte, J.D., and Carter, O. (2015a). Quantitative review finds no evidence of cognitive effects in healthy populations from single-session transcranial direct current stimulation (tDCS). Brain Stimul. 8, 535–550.CrossrefGoogle Scholar
Horvath, J.C., Forte, J.D., and Carter, O. (2015b). Evidence that transcranial direct current stimulation (tDCS) generates little-to-no reliable neurophysiologic effect beyond MEP amplitude modulation in healthy human subjects: a systematic review. Neuropsychologia 66, 213–236.CrossrefGoogle Scholar
Hoyer, E.H. and Celnik, P.A. (2011). Understanding and enhancing motor recovery after stroke using transcranial magnetic stimulation. Restor. Neurol. Neurosci. 29, 395–409.PubMedGoogle Scholar
Hummel, F.C. and Cohen, L.G. (2006). Non-invasive brain stimulation: a new strategy to improve neurorehabilitation after stroke? Lancet Neurol. 5, 708–712.CrossrefPubMedGoogle Scholar
Hummel, F., Celnik, P., Giraux, P., Floel, A., Wu, W.H., Gerloff, C., and Cohen, L.G. (2005). Effects of non-invasive cortical stimulation on skilled motor function in chronic stroke. Brain 128, 490–499.PubMedCrossrefGoogle Scholar
Hummel, F.C., Voller, B., Celnik, P., Floel, A., Giraux, P., Gerloff, C., and Cohen, L.G. (2006). Effects of brain polarization on reaction times and pinch force in chronic stroke. BMC Neurosci. 7, 73.CrossrefPubMedGoogle Scholar
Ilić, N.V., Dubljanin-Raspopović, E., Nedeljković, U., Tomanović-Vujadinović, S., Milanović, S.D., Petronić-Marković, I., and Ilić, T.V. (2016). Effects of anodal tDCS and occupational therapy on fine motor skill deficits in patients with chronic stroke. Restor. Neurol. Neurosci. 34, 935–945.PubMedGoogle Scholar
Ivanenko, Y.P., Poppele, R.E., and Lacquaniti, F. (2009). Distributed neural networks for controlling human locomotion: lessons from normal and SCI subjects. Brain Res. Bull. 78, 13–21.CrossrefPubMedGoogle Scholar
Khedr, E.M., Shawky, O.A., El-Hammady, D.H., Rothwell, J.C., Darwish, E.S., Mostafa, O.M., and Tohamy, A.M. (2013). Effect of anodal versus cathodal transcranial direct current stimulation on stroke rehabilitation: a pilot randomized controlled trial. Neurorehab. Neural Rep. 7, 592–601.Google Scholar
Kim, D.Y., Lim, J.Y., Kang, E.K., You, D.S., Oh, M.K., Oh, B.M., and Paik, N.J. (2010). Effect of transcranial direct current stimulation on motor recovery in patients with subacute stroke. Am. J. Phys. Med. Rehabil. 89, 879–886.PubMedCrossrefGoogle Scholar
Koo, W.R., Jang, B.H., and Kim, C.R. (2018). Effects of anodal transcranial direct current stimulation on somatosensory recovery after stroke: a randomized controlled trial. Am. J. Phys. Med. Rehabil. 97, 507–513.CrossrefPubMedGoogle Scholar
Kwakkel, G. and Kollen, B.J. (2013). Predicting activities after stroke: what is clinically relevant? Int. J. Stroke 8, 25–32.CrossrefPubMedGoogle Scholar
Langhorne, P., Coupar, F., and Pollock, A. (2009). Motor recovery after stroke: a systematic review. Lancet Neurol. 8, 741–754.CrossrefPubMedGoogle Scholar
Lee, S.J. and Chun, M.H. (2014). Combination transcranial direct current stimulation and virtual reality therapy for upper extremity training in patients with subacute stroke. Arch. Phys. Med. Rehab. 95, 431–438.CrossrefGoogle Scholar
Lefaucheur, J.P., Antal, A., Ayache, S.S., Benninger, D.H., Brunelin, J., Cogiamanian, F., Cotelli, M., De Ridder, D., Ferrucci, R., Langguth, B., et al. (2017). Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS). Clin. Neurophysiol. 128, 56–92.CrossrefPubMedGoogle Scholar
Leon, D., Cortes, M., Elder, J., Kumru, H., Laxe, S., Edwards, D.J., Tormos, J.M., Bernabeu, M., and Pascual-Leone, A. (2017). tDCS does not enhance the effects of robot-assisted gait training in patients with subacute stroke. Restor. Neurol. Neurosci. 35, 377–384.PubMedGoogle Scholar
Liew, S.L., Santarnecchi, E., Buch, E.R., and Cohen, L.G. (2014). Non-invasive brain stimulation in neurorehabilitation: local and distant effects for motor recovery. Front. Hum. Neurosci. 8, 378.PubMedGoogle Scholar
Lindenberg, R., Renga, V., Zhu, L.L., Nair, D., and Schlaug, G. (2010). Bihemispheric brain stimulation facilitates motor recovery in chronic stroke patients. Neurology 75, 2176–2184.PubMedCrossrefGoogle Scholar
Lopez-Espuela, F., Zamorano, J.D.P., Ramírez-Moreno, J.M., Jiménez-Caballero, P.E., Portilla-Cuenca, J.C., Lavado-García, J.M., and Casado-Naranjo, I. (2015). Determinants of quality of life in stroke survivors after 6 months, from a comprehensive stroke unit: a longitudinal study. Biol. Res. Nurs. 17, 461–468.CrossrefGoogle Scholar
Lüdemann-Podubecká, J., Bösl, K., Rothhardt, S., Verheyden, G., and Nowak, D.A. (2014). Transcranial direct current stimulation for motor recovery of upper limb function after stroke. Neurosci. Biobehav. Rev. 47, 245–259.PubMedCrossrefGoogle Scholar
Marshall, L., Molle, M., Hallschmid, M., and Born, J. (2004). Transcranial direct current stimulation during sleep improves declarative memory. J. Neurosci. 24, 9985.CrossrefPubMedGoogle Scholar
Mazzoleni, S., Tran, V.D., Iardella, L., Dario, P., and Posteraro, F. (2017). Randomized, sham-controlled trial based on transcranial direct current stimulation and wrist robot-assisted integrated treatment on subacute stroke patients: intermediate results. In: 2017 International Conference on Rehabilitation Robotics (ICORR). IEEE, 555–560. doi:10.1109/icorr.2017.8009306.Google Scholar
Menezes, I.S., Cohen, L.G., Mello, E.A., Machado, A.G., Peckham, P.H., Anjos, S.M., Siqueira, I.L., Conti, J., Plow, E.B., and Conforto, A.B. (2018). Combined brain and peripheral nerve stimulation in chronic stroke patients with moderate to severe motor impairment. Neuromodulation 21, 176–183.CrossrefPubMedGoogle Scholar
Miranda, P.C., Lomarev, M., and Hallett, M. (2006). Modeling the current distribution during transcranial direct current stimulation. Clin. Neurophysiol. 117, 1623–1629.PubMedCrossrefGoogle Scholar
Moher, D., Liberati, A., Tetzlaff, J., and Altman, D.G. (2009). Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann. Int. Med. 151, 264–269.CrossrefGoogle Scholar
Nicolo, P., Magnin, C., Pedrazzini, E., Plomp, G., Mottaz, A., Schnider, A., and Guggisberg, A.G. (2018). Comparison of neuroplastic responses to cathodal transcranial direct current stimulation and continuous theta burst stimulation in subacute stroke. Arch. Phys. Med. Rehab. 99, 862–872.CrossrefGoogle Scholar
Nitsche, M.A. and Paulus, W. (2000). Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J. Physiol. 527, 633–639.CrossrefPubMedGoogle Scholar
Nitsche, M.A. and Paulus, W. (2001). Sustained excitability elevations induced by transcranial DC motor cortex stimulation in humans. Neurology 57, 1899–1901.PubMedCrossrefGoogle Scholar
Nitsche, M.A., Schauenburg, A., Lang, N., Liebetanz, D., Exner, C., Paulus, W., and Tergau, F. (2003). Facilitation of implicit motor learning by weak transcranial direct current stimulation of the primary motor cortex in the human. J. Cogn. Neurosci. 15, 619–626.PubMedCrossrefGoogle Scholar
Nitsche, M.A., Seeber, A., Frommann, K., Klein, C.C., Rochford, C., Nitsche, M.S., Fricke, K., Liebetanz, D., Lang, N., Antal, A., et al. (2005). Modulating parameters of excitability during and after transcranial direct current stimulation of the human motor cortex. J. Physiol. 568, 291–303.CrossrefPubMedGoogle Scholar
Nitsche, M.A., Kuo, M.F., Karrasch, R., Wächter, B., Liebetanz, D., and Paulus, W. (2009). Serotonin affects transcranial direct current-induced neuroplasticity in humans. Biol. Psychiatry 66, 503–508.CrossrefPubMedGoogle Scholar
Nowak, D.A., Bösl, K., Podubeckà, J., and Carey, J.R. (2010). Noninvasive brain stimulation and motor recovery after stroke. Restor. Neurol. Neurosci. 28, 531–544.PubMedGoogle Scholar
Nudo, R.J. and Milliken, G.W. (1996). Reorganization of movement representations in primary motor cortex following focal ischemic infarcts in adult squirrel monkeys. J. Neurophysiol. 75, 2144–2149.PubMedCrossrefGoogle Scholar
Platz, T. (2004). Impairment-oriented training (IOT): scientific concept and evidence-based treatment strategies. Restor. Neurol. Neurosci. 22, 301–315.PubMedGoogle Scholar
Plow, E.B., Carey, J.R., Nudo, R.J., and Pascual-Leone, A. (2009). Invasive cortical stimulation to promote recovery of function after stroke: a critical appraisal. Stroke 40, 1926–1931.PubMedCrossrefGoogle Scholar
Polanía, R., Nitsche, M.A., and Paulus, W. (2011). Modulating functional connectivity patterns and topological functional organization of the human brain with transcranial direct current stimulation. Hum. Brain Mapping 32, 1236–1249.CrossrefGoogle Scholar
Priori, A., Berardelli, A., Rona, S., Accornero, N., and Manfredi, M. (1998). Polarization of the human motor cortex through the scalp. Neuroreport 9, 2257–2260.CrossrefPubMedGoogle Scholar
Rossi, C., Sallustio, F., Di Legge, S., Stanzione, P., and Koch, G. (2013). Transcranial direct current stimulation of the affected hemisphere does not accelerate recovery of acute stroke patients. Eur. J. Neurol. 20, 202–204.CrossrefPubMedGoogle Scholar
Saeys, W., Vereeck, L., Lafosse, C., Truijen, S., Wuyts, F., and Van De Heyning, P. (2015). Transcranial direct current stimulation in the recovery of postural control after stroke: a pilot study. Disabil. Rehabil. 37, 1–7.Google Scholar
Sattler, V., Acket, B., Raposo, N., Thalamas, C., Loubinoux, I., Chollet, F., and Simonetta-Moreau, M. (2015). Anodal tDCS combined with radial nerve stimulation promotes hand motor recovery in the acute phase after ischemic stroke. Neurorehab. Neural Rep. 29, 743–754.CrossrefGoogle Scholar
Seo, H.G., Lee, W.H., Lee, S.H., Yi, Y., Kim, K.D., and Oh, B.M. (2017). Robotic-assisted gait training combined with transcranial direct current stimulation in chronic stroke patients: a pilot double-blind, randomized controlled trial. Restor. Neurol. Neurosci. 35, 527–536.PubMedGoogle Scholar
Shekhawat, G.S., Searchfield, G.D., and Stinear, C.M. (2013a). Randomized trial of transcranial direct current stimulation and hearing aids for tinnitus management. Neurorehab. Neural Rep. 28, 410–419.Google Scholar
Simonetti, D., Zollo, L., Milighetti, S., Miccinilli, S., Bravi, M., Ranieri, F., Magrone, G., Guglielmelli, E., Di Lazzaro, V., and Sterzi, S. (2017). Literature review on the effects of tDCS coupled with robotic therapy in post stroke upper limb rehabilitation. Front. Hum. Neurosci. 11, 268.CrossrefPubMedGoogle Scholar
Stinear, C.M. and Byblow, W.D. (2014). Predicting and accelerating motor recovery after stroke. Curr. Opin. Neurol. 27, 624–630.PubMedGoogle Scholar
Straudi, S., Fregni, F., Martinuzzi, C., Pavarelli, C., Salvioli, S., and Basaglia, N. (2016). tDCS and robotics on upper limb stroke rehabilitation: effect modification by stroke duration and type of stroke. BioMed Res. Int. 2016, 8.Google Scholar
Suzuki, Y., and Naito, E. (2012). Neuro-modulation in dorsal premotor cortex facilitates human multi-task ability. J. Behav. Brain Sci. 2, 372.CrossrefGoogle Scholar
Terney, D., Chaieb, L., Moliadze, V., Antal, A., and Paulus, W. (2008). Increasing human brain excitability by transcranial high-frequency random noise stimulation. J. Neurosci. 28, 14147–14155.CrossrefPubMedGoogle Scholar
Viana, R.T., Laurentino, G.E., Souza, R.J., Fonseca, J.B., Silva Filho, E.M., Dias, S.N., Teixeira-Salmela, L.F., and Monte-Silva, K.K. (2014). Effects of the addition of transcranial direct current stimulation to virtual reality therapy after stroke: a pilot randomized controlled trial. Neurorehabilitation 34, 437–446.PubMedGoogle Scholar
Wang, Y., Shen, Y., Cao, X., Shan, C., Pan, J., He, H., Ma, Y., and Yuan, T.F. (2016). Transcranial direct current stimulation of the frontal-parietal-temporal area attenuates cue-induced craving for heroin. J. Psychiatry Res. 79, 1–3.CrossrefGoogle Scholar
Wu, D., Qian, L., Zorowitz, R.D., Zhang, L., Qu, Y., and Yuan, Y. (2013). Effects on decreasing upper-limb post stroke muscle tone using transcranial direct current stimulation: a randomized sham-controlled study. Arch. Phys. Med. Rehab. 94, 1–8.CrossrefGoogle Scholar
Zehr, E.P. (2005). Neural control of rhythmic human movement: the common core hypothesis. Exercise Sport Sci. Rev. 33, 54–60.Google Scholar
Ziemann, U., Paulus, W., Nitsche, M.A., Pascual-Leone, A., Byblow, W.D., Berardelli, A., Siebner, H.R., Classen, J., Cohen, L.G., and Rothwell, J.C. (2008). Consensus: motor cortex plasticity protocols. Brain Stimul. 1, 164–182.CrossrefPubMedGoogle Scholar
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.
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.
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.
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.
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).
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.
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
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 [1, 2], 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 [5, 6, 7]. The most commonly reported adverse effects included redness, tingling and itching sensations under the electrodes, as well as headache [6, 8]. 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?
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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., 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.
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.,
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.,, Recently, tDCS has also been tried on normal individuals and was shown to improve cognition, working memory, and performance.,, 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.
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.[…]