Effectiveness of transcranial direct current stimulation and visual illusion on neuropathic pain in spinal cord injury

PubMed Central

Kumru, Hatice; Pelayo, Raul; Vidal, Joan; Tormos, Josep Maria; Fregni, Felipe; Navarro, Xavier; Pascual-Leone, Alvaro

2010-01-01

The aim of this study was to evaluate the analgesic effect of transcranial direct current stimulation of the motor cortex and techniques of visual illusion, applied isolated or combined, in patients with neuropathic pain following spinal cord injury. In a sham controlled, double-blind, parallel group design, 39 patients were randomized into four groups receiving transcranial direct current stimulation with walking visual illusion or with control illusion and sham stimulation with visual illusion or with control illusion. For transcranial direct current stimulation, the anode was placed over the primary motor cortex. Each patient received ten treatment sessions during two consecutive weeks. Clinical assessment was performed before, after the last day of treatment, after 2 and 4 weeks follow-up and after 12 weeks. Clinical assessment included overall pain intensity perception, Neuropathic Pain Symptom Inventory and Brief Pain Inventory. The combination of transcranial direct current stimulation and visual illusion reduced the intensity of neuropathic pain significantly more than any of the single interventions. Patients receiving transcranial direct current stimulation and visual illusion experienced a significant improvement in all pain subtypes, while patients in the transcranial direct current stimulation group showed improvement in continuous and paroxysmal pain, and those in the visual illusion group improved only in continuous pain and dysaesthesias. At 12 weeks after treatment, the combined treatment group still presented significant improvement on the overall pain intensity perception, whereas no improvements were reported in the other three groups. Our results demonstrate that transcranial direct current stimulation and visual illusion can be effective in the management of neuropathic pain following spinal cord injury, with minimal side effects and with good tolerability. PMID:20685806

Transcranial Direct Current Stimulation in Epilepsy.

PubMed

San-Juan, Daniel; Morales-Quezada, León; Orozco Garduño, Adolfo Josué; Alonso-Vanegas, Mario; González-Aragón, Maricarmen Fernández; Espinoza López, Dulce Anabel; Vázquez Gregorio, Rafael; Anschel, David J; Fregni, Felipe

2015-01-01

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation therapy in epilepsy with conflicting results in terms of efficacy and safety. Review the literature about the efficacy and safety of tDCS in epilepsy in humans and animals. We searched studies in PubMed, MedLine, Scopus, Web of Science and Google Scholar (January 1969 to October 2013) using the keywords 'transcranial direct current stimulation' or 'tDCS' or 'brain polarization' or 'galvanic stimulation' and 'epilepsy' in animals and humans. Original articles that reported tDCS safety and efficacy in epileptic animals or humans were included. Four review authors independently selected the studies, extracted data and assessed the methodological quality of the studies using the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, PRISMA guidelines and Jadad Scale. A meta-analysis was not possible due to methodological, clinical and statistical heterogeneity of included studies. We analyzed 9 articles with different methodologies (3 animals/6 humans) with a total of 174 stimulated individuals; 109 animals and 65 humans. In vivo and in vitro animal studies showed that direct current stimulation can successfully induce suppression of epileptiform activity without neurological injury and 4/6 (67%) clinical studies showed an effective decrease in epileptic seizures and 5/6 (83%) reduction of inter-ictal epileptiform activity. All patients tolerated tDCS well. tDCS trials have demonstrated preliminary safety and efficacy in animals and patients with epilepsy. Further larger studies are needed to define the best stimulation protocols and long-term follow-up. Copyright © 2015 Elsevier Inc. All rights reserved.

Combining physical training with transcranial direct current stimulation to improve gait in Parkinson's disease: a pilot randomized controlled study.

PubMed

Kaski, D; Dominguez, R O; Allum, J H; Islam, A F; Bronstein, A M

2014-11-01

To improve gait and balance in patients with Parkinson's disease by combining anodal transcranial direct current stimulation with physical training. In a double-blind design, one group (physical training; n = 8) underwent gait and balance training during transcranial direct current stimulation (tDCS; real/sham). Real stimulation consisted of 15 minutes of 2 mA transcranial direct current stimulation over primary motor and premotor cortex. For sham, the current was switched off after 30 seconds. Patients received the opposite stimulation (sham/real) with physical training one week later; the second group (No physical training; n = 8) received stimulation (real/sham) but no training, and also repeated a sequential transcranial direct current stimulation session one week later (sham/real). Hospital Srio Libanes, Buenos Aires, Argentina. Sixteen community-dwelling patients with Parkinson's disease. Transcranial direct current stimulation with and without concomitant physical training. Gait velocity (primary gait outcome), stride length, timed 6-minute walk test, Timed Up and Go Test (secondary outcomes), and performance on the pull test (primary balance outcome). Transcranial direct current stimulation with physical training increased gait velocity (mean = 29.5%, SD = 13; p < 0.01) and improved balance (pull test: mean = 50.9%, SD = 37; p = 0.01) compared with transcranial direct current stimulation alone. There was no isolated benefit of transcranial direct current stimulation alone. Although physical training improved gait velocity (mean = 15.5%, SD = 12.3; p = 0.03), these effects were comparatively less than with combined tDCS + physical therapy (p < 0.025). Greater stimulation-related improvements were seen in patients with more advanced disease. Anodal transcranial direct current stimulation during physical training improves gait and balance in patients with Parkinson's disease. Power calculations revealed that 14 patients per treatment arm (α = 0.05; power = 0

Transcranial Direct Current Stimulation Does Not Improve Language Outcome in Subacute Poststroke Aphasia.

PubMed

Spielmann, Kerstin; van de Sandt-Koenderman, W Mieke E; Heijenbrok-Kal, Majanka H; Ribbers, Gerard M

2018-04-01

The aim of the present study is to investigate the effect of transcranial direct current stimulation on word-finding treatment outcome in subacute poststroke aphasia. In this multi-center, double-blind, randomized controlled trial with 6-month follow-up, we included 58 patients with subacute aphasia (<3 months poststroke), who were enrolled in a stroke rehabilitation program. Patients participated in 2 separate intervention weeks. Each intervention week included 5 daily sessions of 45-minute word-finding therapy combined with either anodal transcranial direct current stimulation (1 mA, 20 minutes; experimental group) or sham transcranial direct current stimulation (control group) over the left inferior frontal gyrus. The primary outcome measure was the Boston Naming Test. Secondary outcome measures included naming performance for trained/untrained picture items and verbal communication. Both the experimental (n=26) and the control group (n=32) improved on the Boston Naming Test over the intervention period and 6-month follow-up; however, there were no significant differences between groups. Also for the secondary outcome measures, no significant differences were found. The results of the present study do not support an effect of transcranial direct current stimulation as an adjuvant treatment in subacute poststroke aphasia. URL: http://www.trialregister.nl/trialreg/admin/rctview.asp. Unique identifier: NTR4364. © 2018 American Heart Association, Inc.

Cerebellar transcranial direct current stimulation in patients with ataxia: A double-blind, randomized, sham-controlled study.

PubMed

Benussi, Alberto; Koch, Giacomo; Cotelli, Maria; Padovani, Alessandro; Borroni, Barbara

2015-10-01

Numerous studies have highlighted the possibility of modulating the excitability of cerebellar circuits using transcranial direct current stimulation. The present study investigated whether a single session of cerebellar anodal transcranial direct current stimulation could improve symptoms in patients with ataxia. Nineteen patients with ataxia underwent a clinical and functional evaluation pre- and post-double-blind, randomized, sham, or anodal transcranial direct current stimulation. There was a significant interaction between treatment and time on the Scale for the Assessment and Rating of Ataxia, on the International Cooperative Ataxia Rating Scale, on the 9-Hole Peg Test, and on the 8-Meter Walking Time (P < 0.001). At the end of the sessions, all performance scores were significantly different in the sham trial, compared to the intervention trial. A single session of anodal cerebellar transcranial direct current stimulation can transiently improve symptoms in patients with ataxia and might represent a promising tool for future rehabilitative approaches. © 2015 International Parkinson and Movement Disorder Society.

Transcranial direct current stimulation for depression in Alzheimer's disease: study protocol for a randomized controlled trial.

PubMed

Narita, Zui; Yokoi, Yuma

2017-06-19

Patients with Alzheimer's disease frequently elicit neuropsychiatric symptoms as well as cognitive deficits. Above all, depression is one of the most common neuropsychiatric symptoms in Alzheimer's disease but antidepressant drugs have not shown significant beneficial effects on it. Moreover, electroconvulsive therapy has not ensured its safety for potential severe adverse events although it does show beneficial clinical effect. Transcranial direct current stimulation can be the safe alternative of neuromodulation, which applies weak direct electrical current to the brain. Although transcranial direct current stimulation has plausible evidence for its effect on depression in young adult patients, no study has explored it in older subjects with depression in Alzheimer's disease. Therefore, we present a study protocol designed to evaluate the safety and clinical effect of transcranial direct current stimulation on depression in Alzheimer's disease in subjects aged over 65 years. This is a two-arm, parallel-design, randomized controlled trial, in which patients and assessors will be blinded. Subjects will be randomized to either an active or a sham transcranial direct current stimulation group. Participants in both groups will be evaluated at baseline, immediately, and 2 weeks after the intervention. This study investigates the safety and effect of transcranial direct current stimulation that may bring a significant impact on both depression and cognition in patients with Alzheimer's disease, and may be useful to enhance their quality of life. ClinicalTrials.gov, NCT02351388 . Registered on 27 January 2015. Last updated on 30 May 2016.

Transcranial Direct Current Stimulation in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder (ADHD): A Pilot Study.

PubMed

Bandeira, Igor Dórea; Guimarães, Rachel Silvany Quadros; Jagersbacher, João Gabriel; Barretto, Thiago Lima; de Jesus-Silva, Jéssica Regina; Santos, Samantha Nunes; Argollo, Nayara; Lucena, Rita

2016-06-01

Studies investigating the possible benefits of transcranial direct current stimulation on left dorsolateral prefrontal cortex in children and adolescents with attention-deficit hyperactivity disorder (ADHD) have not been performed. This study assesses the effect of transcranial direct current stimulation in children and adolescents with ADHD on neuropsychological tests of visual attention, visual and verbal working memory, and inhibitory control. An auto-matched clinical trial was performed involving transcranial direct current stimulation in children and adolescents with ADHD, using SNAP-IV and subtests Vocabulary and Cubes of the Wechsler Intelligence Scale for Children III (WISC-III). Subjects were assessed before and after transcranial direct current stimulation sessions with the Digit Span subtest of the WISC-III, inhibitory control subtest of the NEPSY-II, Corsi cubes, and the Visual Attention Test (TAVIS-3). There were 9 individuals with ADHD according to Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria. There was statistically significant difference in some aspects of TAVIS-3 tests and the inhibitory control subtest of NEPSY-II. Transcranial direct current stimulation can be related to a more efficient processing speed, improved detection of stimuli, and improved ability to switch between an ongoing activity and a new one. © The Author(s) 2016.

Frontal transcranial direct current stimulation (tDCS) abolishes list-method directed forgetting.

PubMed

Silas, Jonathan; Brandt, Karen R

2016-03-11

It is a point of controversy as to whether directed forgetting effects are a result of active inhibition or a change of context initiated by the instruction to forget. In this study we test the causal role of active inhibition in directed forgetting. By applying cathodal transcranial direct current stimulation (tDCS) over the right prefrontal cortex we suppressed cortical activity commonly associated with inhibitory control. Participants who underwent real brain stimulation before completing the directed forgetting paradigm showed no directed forgetting effects. Conversely, those who underwent sham brain stimulation demonstrated classical directed forgetting effects. We argue that these findings suggest that inhibition is the primary mechanism that results in directed forgetting costs and benefits. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Treatment of Memory Disorders in Gulf War Illness with High-Definition Transcranial Direct Cortical Stimulation

DTIC Science & Technology

2017-10-01

AWARD NUMBER: W81XWH-16-1-0521 TITLE: Treatment of Memory Disorders in Gulf War Illness with High - Definition Transcranial Direct Cortical...Approved for Public Release; Distribution Unlimited The views, opinions and/or findings contained in this report are those of the author(s) and should...Sep 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Treatment of Memory Disorders in Gulf War Illness with High -Definition Transcranial Direct

Neuroprotective effect of cathodal transcranial direct current stimulation in a rat stroke model.

PubMed

Notturno, Francesca; Pace, Marta; Zappasodi, Filippo; Cam, Etrugul; Bassetti, Claudio L; Uncini, Antonino

2014-07-15

Experimental focal brain ischemia generates in the penumbra recurrent depolarizations which spread across the injured cortex inducing infarct growth. Transcranial direct current stimulation can induce a lasting, polarity-specific, modulation of cortical excitability. To verify whether cathodal transcranial direct current stimulation could reduce the infarct size and the number of depolarizations, focal ischemia was induced in the rat by the 3 vessels occlusion technique. In the first experiment 12 ischemic rats received cathodal stimulation (alternating 15 min on and 15 min off) starting 45 min after middle cerebral artery occlusion and lasting 4 h. In the second experiment 12 ischemic rats received cathodal transcranial direct current stimulation with the same protocol but starting soon after middle cerebral artery occlusion and lasting 6 h. In both experiments controls were 12 ischemic rats not receiving stimulation. Cathodal stimulation reduced the infarct volume in the first experiment by 20% (p=0.002) and in the second by 30% (p=0.003). The area of cerebral infarction was smaller in animals receiving cathodal stimulation in both experiments (p=0.005). Cathodal stimulation reduced the number of depolarizations (p=0.023) and infarct volume correlated with the number of depolarizations (p=0.048). Our findings indicate that cathodal transcranial direct current stimulation exert a neuroprotective effect in the acute phase of stroke possibly decreasing the number of spreading depolarizations. These findings may have translational relevance and open a new avenue in neuroprotection of stroke in humans. Copyright © 2014. Published by Elsevier B.V.

Transcranial direct-current stimulation induced in stroke patients with aphasia: a prospective experimental cohort study.

PubMed

Santos, Michele Devido; Gagliardi, Rubens José; Mac-Kay, Ana Paula Machado Goyano; Boggio, Paulo Sergio; Lianza, Roberta; Fregni, Felipe

2013-01-01

Previous animal and human studies have shown that transcranial direct current stimulation can induce significant and lasting neuroplasticity and may improve language recovery in patients with aphasia. The objective of the study was to describe a cohort of patients with aphasia after stroke who were treated with transcranial direct current stimulation. Prospective cohort study developed in a public university hospital. Nineteen patients with chronic aphasia received 10 transcranial direct current stimulation sessions lasting 20 minutes each on consecutive days, using a current of 2 mA. The anode was positioned over the supraorbital area and the cathode over the contralateral motor cortex. The following variables were analyzed before and after the 10 neuromodulation sessions: oral language comprehension, copying, dictation, reading, writing, naming and verbal fluency. There were no adverse effects in the study. We found statistically significant differences from before to after stimulation in relation to simple sentence comprehension (P = 0.034), naming (P = 0.041) and verbal fluency for names of animals (P = 0.038). Improved scores for performing these three tasks were seen after stimulation. We observed that excitability of the primary motor cortex through transcranial direct current stimulation was associated with effects on different aspects of language. This can contribute towards future testing in randomized controlled trials.

Repetitive transcranial magnetic stimulation and transcranial direct-current stimulation in neuropathic pain due to radiculopathy: a randomized sham-controlled comparative study.

PubMed

Attal, Nadine; Ayache, Samar S; Ciampi De Andrade, Daniel; Mhalla, Alaa; Baudic, Sophie; Jazat, Frédérique; Ahdab, Rechdi; Neves, Danusa O; Sorel, Marc; Lefaucheur, Jean-Pascal; Bouhassira, Didier

2016-06-01

No study has directly compared the effectiveness of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS) in neuropathic pain (NP). In this 2-centre randomised double-blind sham-controlled study, we compared the efficacy of 10-Hz rTMS and anodal 2-mA tDCS of the motor cortex and sham stimulation contralateral to the painful area (3 daily sessions) in patients with NP due to lumbosacral radiculopathy. Average pain intensity (primary outcome) was evaluated after each session and 5 days later. Secondary outcomes included neuropathic symptoms and thermal pain thresholds for the upper limbs. We used an innovative design that minimised bias by randomly assigning patients to 1 of 2 groups: active rTMS and tDCS or sham rTMS and tDCS. For each treatment group (active or sham), the order of the sessions was again randomised according to a crossover design. In total, 51 patients were screened and 35 (51% women) were randomized. Active rTMS was superior to tDCS and sham in pain intensity (F = 2.89 and P = 0.023). Transcranial direct-current stimulation was not superior to sham, but its analgesic effects were correlated to that of rTMS (P = 0.046), suggesting common mechanisms of action. Repetitive transcranial magnetic stimulation lowered cold pain thresholds (P = 0.04) and its effect on cold pain was correlated with its analgesic efficacy (P = 0.006). However, rTMS had no impact on individual neuropathic symptoms. Thus, rTMS is more effective than tDCS and sham in patients with NP due to lumbosacral radiculopathy and may modulate the sensory and affective dimensions of pain.

Mild cognitive impairment in Parkinson's disease is improved by transcranial direct current stimulation combined with physical therapy.

PubMed

Manenti, Rosa; Brambilla, Michela; Benussi, Alberto; Rosini, Sandra; Cobelli, Chiara; Ferrari, Clarissa; Petesi, Michela; Orizio, Italo; Padovani, Alessandro; Borroni, Barbara; Cotelli, Maria

2016-05-01

Parkinson's disease (PD) is characterized by both motor and cognitive deficits. In PD, physical exercise has been found to improve physical functioning. Recent studies demonstrated that repeated sessions of transcranial direct current stimulation led to an increased performance in cognitive and motor tasks in patients with PD. The present study investigated the effects of anodal transcranial direct current stimulation applied over the dorsolateral prefrontal cortex and combined with physical therapy in PD patients. A total of 20 patients with PD were assigned to 1 of 2 study groups: group 1, anodal transcranial direct current stimulation plus physical therapy (n = 10) or group 2, placebo transcranial direct current stimulation plus physical therapy (n = 10). The 2 weeks of treatment consisted of daily direct current stimulation application for 25 minutes during physical therapy. Long-term effects of treatment were evaluated on clinical, neuropsychological, and motor task performance at 3-month follow-up. An improvement in motor abilities and a reduction of depressive symptoms were observed in both groups after the end of treatment and at 3-month follow-up. The Parkinson's Disease Cognitive Rating Scale and verbal fluency test performances increased only in the anodal direct current stimulation group with a stable effect at follow-up. The application of anodal transcranial direct current stimulation may be a relevant tool to improve cognitive abilities in PD and might be a novel therapeutic strategy for PD patients with mild cognitive impairment. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

Cathodal transcranial direct current stimulation in children with dystonia: a sham-controlled study.

PubMed

Young, Scott J; Bertucco, Matteo; Sanger, Terence D

2014-02-01

Increased motor cortex excitability is a common finding in dystonia, and transcranial direct current stimulation can reduce motor cortex excitability. In an earlier study, we found that cathodal direct-current stimulation decreased motor overflow for some children with dystonia. To investigate this observation further, we performed a sham-controlled, double-blind, crossover study of 14 children with dystonia. We found a significant reduction in overflow following real stimulation, when participants performed the experimental task with the hand contralateral to the cathode. While these results suggest that cathodal stimulation may help some children to reduce involuntary overflow, the size of the effect is small. Further research will need to investigate ways to increase the magnitude of the effect of cathodal transcranial direct current stimulation.

Noninvasive techniques for probing neurocircuitry and treating illness: vagus nerve stimulation (VNS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS)

PubMed Central

George, Mark S; Aston-Jones, Gary

2010-01-01

Although the preceding chapters discuss much of the new knowledge of neurocircuitry of neuropsychiatric diseases, and an invasive approach to treatment, this chapter describes and reviews the noninvasive methods of testing circuit-based theories and treating neuropsychiatric diseases that do not involve implanting electrodes into the brain or on its surface. These techniques are transcranial magnetic stimulation, vagus nerve stimulation, and transcranial direct current stimulation. Two of these approaches have FDA approval as therapies. PMID:19693003

Clinical Research with Transcranial Direct Current Stimulation (tDCS): Challenges and Future Directions

PubMed Central

Brunoni, Andre Russowsky; Nitsche, Michael A.; Bolognini, Nadia; Bikson, Marom; Wagner, Tim; Merabet, Lotfi; Edwards, Dylan J.; Valero-Cabre, Antoni; Rotenberg, Alexander; Pascual-Leone, Alvaro; Ferrucci, Roberta; Priori, Alberto; Boggio, Paulo; Fregni, Felipe

2011-01-01

Background Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity, direct current to cortical areas facilitating or inhibiting spontaneous neuronal activity. In the past ten years, tDCS physiological mechanisms of action have been intensively investigated giving support for the investigation of its applications in clinical neuropsychiatry and rehabilitation. However, new methodological, ethical, and regulatory issues emerge when translating the findings of preclinical and phase I studies into phase II and III clinical studies. The aim of this comprehensive review is to discuss the key challenges of this process and possible methods to address them. Methods We convened a workgroup of researchers in the field to review, discuss and provide updates and key challenges of neuromodulation use for clinical research. Main Findings/Discussion We reviewed several basic and clinical studies in the field and identified potential limitations, taking into account the particularities of the technique. We review and discuss the findings into four topics: (i) mechanisms of action of tDCS, parameters of use and computer-based human brain modeling investigating electric current fields and magnitude induced by tDCS; (ii) methodological aspects related to the clinical research of tDCS as divided according to study phase (i.e., preclinical, phase I, phase II and phase III studies); (iii) ethical and regulatory concerns; (iv) future directions regarding novel approaches, novel devices, and future studies involving tDCS. Finally, we propose some alternative methods to facilitate clinical research on tDCS. PMID:22037126

Transcranial direct current stimulation over left inferior frontal cortex improves speech fluency in adults who stutter.

PubMed

Chesters, Jennifer; Möttönen, Riikka; Watkins, Kate E

2018-04-01

See Crinion (doi:10.1093/brain/awy075) for a scientific commentary on this article.Stuttering is a neurodevelopmental condition affecting 5% of children, and persisting in 1% of adults. Promoting lasting fluency improvement in adults who stutter is a particular challenge. Novel interventions to improve outcomes are of value, therefore. Previous work in patients with acquired motor and language disorders reported enhanced benefits of behavioural therapies when paired with transcranial direct current stimulation. Here, we report the results of the first trial investigating whether transcranial direct current stimulation can improve speech fluency in adults who stutter. We predicted that applying anodal stimulation to the left inferior frontal cortex during speech production with temporary fluency inducers would result in longer-lasting fluency improvements. Thirty male adults who stutter completed a randomized, double-blind, controlled trial of anodal transcranial direct current stimulation over left inferior frontal cortex. Fifteen participants received 20 min of 1-mA stimulation on five consecutive days while speech fluency was temporarily induced using choral and metronome-timed speech. The other 15 participants received the same speech fluency intervention with sham stimulation. Speech fluency during reading and conversation was assessed at baseline, before and after the stimulation on each day of the 5-day intervention, and at 1 and 6 weeks after the end of the intervention. Anodal stimulation combined with speech fluency training significantly reduced the percentage of disfluent speech measured 1 week after the intervention compared with fluency intervention alone. At 6 weeks after the intervention, this improvement was maintained during reading but not during conversation. Outcome scores at both post-intervention time points on a clinical assessment tool (the Stuttering Severity Instrument, version 4) also showed significant improvement in the group receiving

Transcranial Direct Current Stimulation Potentiates Improvements in Functional Ability in Patients With Chronic Stroke Receiving Constraint-Induced Movement Therapy.

PubMed

Figlewski, Krystian; Blicher, Jakob Udby; Mortensen, Jesper; Severinsen, Kåre Eg; Nielsen, Jørgen Feldbæk; Andersen, Henning

2017-01-01

Transcranial direct current stimulation may enhance effect of rehabilitation in patients with chronic stroke. The objective was to evaluate the efficacy of anodal transcranial direct current stimulation combined with constraint-induced movement therapy of the paretic upper limb. A total of 44 patients with stroke were randomly allocated to receive 2 weeks of constraint-induced movement therapy with either anodal or sham transcranial direct current stimulation. The primary outcome measure, Wolf Motor Function Test, was assessed at baseline and after the intervention by blinded investigators. Both groups improved significantly on all Wolf Motor Function Test scores. Group comparison showed improvement on Wolf Motor Function Test in the anodal group compared with the sham group. Anodal transcranial direct current stimulation combined with constraint-induced movement therapy resulted in improvement of functional ability of the paretic upper limb compared with constraint-induced movement therapy alone. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01983319. © 2016 American Heart Association, Inc.

Cathodal Transcranial Direct Current Stimulation of the Right Wernicke's Area Improves Comprehension in Subacute Stroke Patients

ERIC Educational Resources Information Center

You, Dae Sang; Kim, Dae-Yul; Chun, Min Ho; Jung, Seung Eun; Park, Sung Jong

2011-01-01

Previous studies have shown the appearance of right-sided language-related brain activity in right-handed patients after a stroke. Non-invasive brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) have been shown to modulate excitability in the brain. Moreover, rTMS and…

Transcranial direct current stimulation for acute major depressive episodes: meta-analysis of individual patient data

PubMed Central

Brunoni, André R.; Moffa, Adriano H.; Fregni, Felipe; Palm, Ulrich; Padberg, Frank; Blumberger, Daniel M.; Daskalakis, Zafiris J.; Bennabi, Djamila; Haffen, Emmanuel; Alonzo, Angelo; Loo, Colleen K.

2016-01-01

Background Transcranial direct current stimulation (tDCS) is a non-pharmacological intervention for depression. It has mixed results, possibly caused by study heterogeneity. Aims To assess tDCS efficacy and to explore individual response predictors. Method Systematic review and individual patient data meta-analysis. Results Data were gathered from six randomised sham-controlled trials, enrolling 289 patients. Active tDCS was significantly superior to sham for response (34% v. 19% respectively, odds ratio (OR) = 2.44, 95% CI 1.38–4.32, number needed to treat (NNT) = 7), remission (23.1% v. 12.7% respectively, OR = 2.38, 95% CI 1.22–4.64, NNT = 9) and depression improvement (B coefficient 0.35, 95% CI 0.12–0.57). Mixed-effects models showed that, after adjustment for other predictors and confounders, treatment-resistant depression and higher tDCS ‘doses’ were, respectively, negatively and positively associated with tDCS efficacy. Conclusions The effect size of tDCS treatment was comparable with those reported for repetitive transcranial magnetic stimulation and antidepressant drug treatment in primary care. The most important parameters for optimisation in future trials are depression refractoriness and tDCS dose. PMID:27056623

Considering the influence of stimulation parameters on the effect of conventional and high-definition transcranial direct current stimulation.

PubMed

To, Wing Ting; Hart, John; De Ridder, Dirk; Vanneste, Sven

2016-01-01

Recently, techniques to non-invasively modulate specific brain areas gained popularity in the form of transcranial direct current stimulation (tDCS) and high-definition transcranial direct current stimulation. These non-invasive techniques have already shown promising outcomes in various studies with healthy subjects as well as patient populations. Despite widespread dissemination of tDCS, there remain significant unknowns about the influence of a diverse number of tDCS parameters (e.g. polarity, size, position of electrodes & duration of stimulation) in inducing neurophysiological and behavioral effects. This article explores both techniques starting with the history of tDCS, to the differences between conventional tDCS and high-definition transcranial direct current stimulation, the underlying physiological mechanism, the (in)direct effects, the applications of tDCS with varying parameters, the efficacy, the safety issues and the opportunities for future research.

Imaging transcranial direct current stimulation (tDCS) of the prefrontal cortex-correlation or causality in stimulation-mediated effects?

PubMed

Wörsching, Jana; Padberg, Frank; Ertl-Wagner, Birgit; Kumpf, Ulrike; Kirsch, Beatrice; Keeser, Daniel

2016-10-01

Transcranial current stimulation approaches include neurophysiologically distinct non-invasive brain stimulation techniques widely applied in basic, translational and clinical research: transcranial direct current stimulation (tDCS), oscillating transcranial direct current stimulation (otDCS), transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS). Prefrontal tDCS seems to be an especially promising tool for clinical practice. In order to effectively modulate relevant neural circuits, systematic research on prefrontal tDCS is needed that uses neuroimaging and neurophysiology measures to specifically target and adjust this method to physiological requirements. This review therefore analyses the various neuroimaging methods used in combination with prefrontal tDCS in healthy and psychiatric populations. First, we provide a systematic overview on applications, computational models and studies combining neuroimaging or neurophysiological measures with tDCS. Second, we categorise these studies in terms of their experimental designs and show that many studies do not vary the experimental conditions to the extent required to demonstrate specific relations between tDCS and its behavioural or neurophysiological effects. Finally, to support best-practice tDCS research we provide a methodological framework for orientation among experimental designs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of transcranial direct current stimulation on craving, heart-rate variability and prefrontal hemodynamics during smoking cue exposure.

PubMed

Kroczek, A M; Häußinger, F B; Rohe, T; Schneider, S; Plewnia, C; Batra, A; Fallgatter, A J; Ehlis, A-C

2016-11-01

Drug-related cue exposure elicits craving and risk for relapse during recovery. Transcranial direct current stimulation is a promising research tool and possible treatment for relapse prevention. Enhanced functional neuroconnectivity is discussed as a treatment target. The goal of this research was to examine whether transcranial direct current stimulation affected cortical hemodynamic indicators of functional connectivity, craving, and heart rate variability during smoking-related cue exposure in non-treatment-seeking smokers. In vivo smoking cue exposure supported by a 2mA transcranial direct current stimulation (anode: dorsolateral prefrontal cortex, cathode: orbitofrontal cortex; placebo-controlled, randomized, double-blind) in 29 (age: M=25, SD=5) German university students (smoking at least once a week). Cue reactivity was assessed on an autonomous (heart rate variability) and a subjective level (craving ratings). Functional near-infrared spectroscopy measured changes in the concentration of deoxygenated hemoglobin, and seed-based correlation analysis was used to quantify prefrontal connectivity of brain regions involved in cue reactivity. Cue exposure elicited increased subjective craving and heart rate variability changes in smokers. Connectivity between the orbitofrontal and dorsolateral prefrontal cortex was increased in subjects receiving verum compared to placebo stimulation (d=0.66). Hemodynamics in the left dorsolateral prefrontal cortex, however, increased in the group receiving sham stimulation (η 2 =0.140). Transcranial direct current stimulation did not significantly alter craving or heart rate variability during cue exposure. Prefrontal connectivity - between regions involved in the processing of reinforcement value and cognitive control - was increased by anodal transcranial direct current stimulation during smoking cue exposure. Possible clinical implications should be considered in future studies. Copyright © 2016 Elsevier Ireland Ltd. All

Efficacy of transcranial direct-current stimulation (tDCS) in women with provoked vestibulodynia: study protocol for a randomized controlled trial.

PubMed

Morin, Annie; Léonard, Guillaume; Gougeon, Véronique; Waddell, Guy; Bureau, Yves-André; Girard, Isabelle; Morin, Mélanie

2016-05-14

Provoked vestibulodynia is the most common form of vulvodynia. Despite its high prevalence and deleterious sexual, conjugal, and psychological repercussions, effective evidence-based interventions for provoked vestibulodynia remain limited. For a high proportion of women, significant pain persists despite the currently available treatments. Growing evidence suggests that the central nervous system (CNS) could play a key role in provoked vestibulodynia; thus, treatment targeting the CNS, rather than localized dysfunctions, may be beneficial for women suffering from provoked vestibulodynia. In this study, we aim to build on the promising results of a previous case report and evaluate whether transcranial direct-current stimulation, a non-invasive brain stimulation technique targeting the CNS, could be an effective treatment option for women with provoked vestibulodynia. This single-center, triple-blind, parallel group, randomized, controlled trial aims to compare the efficacy of transcranial direct-current stimulation with sham transcranial direct-current stimulation in women with provoked vestibulodynia. Forty women diagnosed with provoked vestibulodynia by a gynecologist, following a standardized treatment protocol, are randomized to either active transcranial direct-current stimulation treatment for ten sessions of 20 minutes at an intensity of 2 mA or sham transcranial direct-current stimulation over a 2-week period. Outcome measures are collected at baseline, 2 weeks after treatment and at 3-month follow-up. The primary outcome is pain during intercourse, assessed with a numerical rating scale. Secondary measurements focus on the sexual function, vestibular pain sensitivity, psychological distress, treatment satisfaction, and the patient's global impression of change. To our knowledge, this study is the first randomized controlled trial to examine the efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia. Findings from this

Tagging motor memories with transcranial direct current stimulation allows later artificially-controlled retrieval

PubMed Central

Nozaki, Daichi; Yokoi, Atsushi; Kimura, Takahiro; Hirashima, Masaya; Orban de Xivry, Jean-Jacques

2016-01-01

We demonstrate that human motor memories can be artificially tagged and later retrieved by noninvasive transcranial direct current stimulation (tDCS). Participants learned to adapt reaching movements to two conflicting dynamical environments that were each associated with a different tDCS polarity (anodal or cathodal tDCS) on the sensorimotor cortex. That is, we sought to determine whether divergent background activity levels within the sensorimotor cortex (anodal: higher activity; cathodal: lower activity) give rise to distinct motor memories. After a training session, application of each tDCS polarity automatically resulted in the retrieval of the motor memory corresponding to that polarity. These results reveal that artificial modulation of neural activity in the sensorimotor cortex through tDCS can act as a context for the formation and recollection of motor memories. DOI: http://dx.doi.org/10.7554/eLife.15378.001 PMID:27472899

Combined Dextroamphetamine and Transcranial Direct Current Stimulation in Poststroke Aphasia.

PubMed

Keser, Zafer; Dehgan, Michelle Weber; Shadravan, Shaparak; Yozbatiran, Nuray; Maher, Lynn M; Francisco, Gerard E

2017-10-01

There is a growing need for various effective adjunctive treatment options for speech recovery after stroke. A pharmacological agent combined with noninvasive brain stimulation has not been previously reported for poststroke aphasia recovery. In this "proof of concept" study, we aimed to test the safety of a combined intervention consisting of dextroamphetamine, transcranial direct current stimulation, and speech and language therapy in subjects with nonfluent aphasia. Ten subjects with chronic nonfluent aphasia underwent two experiments where they received dextroamphetamine or placebo along with transcranial direct current stimulation and speech and language therapy on two separate days. The Western Aphasia Battery-Revised was used to monitor changes in speech performance. No serious adverse events were observed. There was no significant increase in blood pressure with amphetamine or deterioration in speech and language performance. Western Aphasia Battery-Revised aphasia quotient and language quotient showed a statistically significant increase in the active experiment. Comparison of proportional changes of aphasia quotient and language quotient in active experiment with those in placebo experiment showed significant difference. We showed that the triple combination therapy is safe and implementable and seems to induce positive changes in speech and language performance in the patients with chronic nonfluent aphasia due to stroke.

The Effects of Transcranial Direct Current Stimulation (tDCS) on Multitasking Throughput Capacity

PubMed Central

Nelson, Justin; McKinley, Richard A.; Phillips, Chandler; McIntire, Lindsey; Goodyear, Chuck; Kreiner, Aerial; Monforton, Lanie

2016-01-01

Background: Multitasking has become an integral attribute associated with military operations within the past several decades. As the amount of information that needs to be processed during these high level multitasking environments exceeds the human operators' capabilities, the information throughput capacity reaches an asymptotic limit. At this point, the human operator can no longer effectively process and respond to the incoming information resulting in a plateau or decline in performance. The objective of the study was to evaluate the efficacy of a non-invasive brain stimulation technique known as transcranial direct current stimulation (tDCS) applied to a scalp location over the left dorsolateral prefrontal cortex (lDLPFC) to improve information processing capabilities during a multitasking environment. Methods: The study consisted of 20 participants from Wright-Patterson Air Force Base (16 male and 4 female) with an average age of 31.1 (SD = 4.5). Participants were randomly assigned into two groups, each consisting of eight males and two females. Group one received 2 mA of anodal tDCS and group two received sham tDCS over the lDLPFC on their testing day. Results: The findings indicate that anodal tDCS significantly improves the participants' information processing capability resulting in improved performance compared to sham tDCS. For example, the multitasking throughput capacity for the sham tDCS group plateaued near 1.0 bits/s at the higher baud input (2.0 bits/s) whereas the anodal tDCS group plateaued near 1.3 bits/s. Conclusion: The findings provided new evidence that tDCS has the ability to augment and enhance multitasking capability in a human operator. Future research should be conducted to determine the longevity of the enhancement of transcranial direct current stimulation on multitasking performance, which has yet to be accomplished. PMID:27965553

The Effects of Transcranial Direct Current Stimulation (tDCS) on Multitasking Throughput Capacity.

PubMed

Nelson, Justin; McKinley, Richard A; Phillips, Chandler; McIntire, Lindsey; Goodyear, Chuck; Kreiner, Aerial; Monforton, Lanie

2016-01-01

Background: Multitasking has become an integral attribute associated with military operations within the past several decades. As the amount of information that needs to be processed during these high level multitasking environments exceeds the human operators' capabilities, the information throughput capacity reaches an asymptotic limit. At this point, the human operator can no longer effectively process and respond to the incoming information resulting in a plateau or decline in performance. The objective of the study was to evaluate the efficacy of a non-invasive brain stimulation technique known as transcranial direct current stimulation (tDCS) applied to a scalp location over the left dorsolateral prefrontal cortex (lDLPFC) to improve information processing capabilities during a multitasking environment. Methods: The study consisted of 20 participants from Wright-Patterson Air Force Base (16 male and 4 female) with an average age of 31.1 (SD = 4.5). Participants were randomly assigned into two groups, each consisting of eight males and two females. Group one received 2 mA of anodal tDCS and group two received sham tDCS over the lDLPFC on their testing day. Results: The findings indicate that anodal tDCS significantly improves the participants' information processing capability resulting in improved performance compared to sham tDCS. For example, the multitasking throughput capacity for the sham tDCS group plateaued near 1.0 bits/s at the higher baud input (2.0 bits/s) whereas the anodal tDCS group plateaued near 1.3 bits/s. Conclusion: The findings provided new evidence that tDCS has the ability to augment and enhance multitasking capability in a human operator. Future research should be conducted to determine the longevity of the enhancement of transcranial direct current stimulation on multitasking performance, which has yet to be accomplished.

Online effects of transcranial direct current stimulation on prefrontal metabolites in gambling disorder.

PubMed

Dickler, Maya; Lenglos, Christophe; Renauld, Emmanuelle; Ferland, Francine; Edden, Richard A; Leblond, Jean; Fecteau, Shirley

2018-03-15

Gambling disorder is characterized by persistent maladaptive gambling behaviors and is now considered among substance-related and addictive disorders. There is still unmet therapeutic need for these clinical populations, however recent advances indicate that interventions targeting the Glutamatergic/GABAergic system hold promise in reducing symptoms in substance-related and addictive disorders, including gambling disorder. There is some data indicating that transcranial direct current stimulation may hold clinical benefits in substance use disorders and modulate levels of brain metabolites including glutamate and GABA. The goal of the present work was to test whether this non-invasive neurostimulation method modulates key metabolites in gambling disorder. We conducted a sham-controlled, crossover, randomized study, blinded at two levels in order to characterize the effects of transcranial direct current stimulation over the dorsolateral prefrontal cortex on neural metabolites levels in sixteen patients with gambling disorder. Metabolite levels were measured with magnetic resonance spectroscopy from the right dorsolateral prefrontal cortex and the right striatum during active and sham stimulation. Active as compared to sham stimulation elevated prefrontal GABA levels. There were no significant changes between stimulation conditions in prefrontal glutamate + glutamine and N-acetyl Aspartate, or in striatal metabolite levels. Results also indicated positive correlations between metabolite levels during active, but not sham, stimulation and levels of risk taking, impulsivity and craving. Our findings suggest that transcranial direct current stimulation can modulate GABA levels in patients with gambling disorder which may represent an interesting future therapeutic avenue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcranial Direct Current Stimulation (tDCS): A Promising Treatment for Major Depressive Disorder?

PubMed Central

Bennabi, Djamila; Haffen, Emmanuel

2018-01-01

Background: Transcranial direct current stimulation (tDCS) opens new perspectives in the treatment of major depressive disorder (MDD), because of its ability to modulate cortical excitability and induce long-lasting effects. The aim of this review is to summarize the current status of knowledge regarding tDCS application in MDD. Methods: In this review, we searched for articles published in PubMed/MEDLINE from the earliest available date to February 2018 that explored clinical and cognitive effects of tDCS in MDD. Results: Despite differences in design and stimulation parameters, the examined studies indicated beneficial effects of tDCS for MDD. These preliminary results, the non-invasiveness of tDCS, and its good tolerability support the need for further research on this technique. Conclusions: tDCS constitutes a promising therapeutic alternative for patients with MDD, but its place in the therapeutic armamentarium remains to be determined. PMID:29734768

Transcranial direct current stimulation enhances recovery of stereopsis in adults with amblyopia.

PubMed

Spiegel, Daniel P; Li, Jinrong; Hess, Robert F; Byblow, Winston D; Deng, Daming; Yu, Minbin; Thompson, Benjamin

2013-10-01

Amblyopia is a neurodevelopmental disorder of vision caused by abnormal visual experience during early childhood that is often considered to be untreatable in adulthood. Recently, it has been shown that a novel dichoptic videogame-based treatment for amblyopia can improve visual function in adult patients, at least in part, by reducing inhibition of inputs from the amblyopic eye to the visual cortex. Non-invasive anodal transcranial direct current stimulation has been shown to reduce the activity of inhibitory cortical interneurons when applied to the primary motor or visual cortex. In this double-blind, sham-controlled cross-over study we tested the hypothesis that anodal transcranial direct current stimulation of the visual cortex would enhance the therapeutic effects of dichoptic videogame-based treatment. A homogeneous group of 16 young adults (mean age 22.1 ± 1.1 years) with amblyopia were studied to compare the effect of dichoptic treatment alone and dichoptic treatment combined with visual cortex direct current stimulation on measures of binocular (stereopsis) and monocular (visual acuity) visual function. The combined treatment led to greater improvements in stereoacuity than dichoptic treatment alone, indicating that direct current stimulation of the visual cortex boosts the efficacy of dichoptic videogame-based treatment. This intervention warrants further evaluation as a novel therapeutic approach for adults with amblyopia.

Augmenting Visual Search Performance with Transcranial Direct Current Stimulation (tDCS)

DTIC Science & Technology

2015-09-28

Augmenting Visual Search Performance with Transcranial Direct Current Stimulation ( tDCS ) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62202F...stimulation ( tDCS ) over the left frontal eye field (LFEF) region of the scalp to improve cognitive performance. The participants received anodal and...blinking frequency in relation to stimulation condition. Our data suggest that tDCS over the LFEF would be a beneficial countermeasure to mitigate the

Combined effects of cerebellar transcranial direct current stimulation and transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke: A pilot, single blind, randomized controlled trial.

PubMed

Picelli, Alessandro; Chemello, Elena; Castellazzi, Paola; Filippetti, Mirko; Brugnera, Annalisa; Gandolfi, Marialuisa; Waldner, Andreas; Saltuari, Leopold; Smania, Nicola

2018-01-01

Preliminary evidence showed additional effects of anodal transcranial direct current stimulation over the damaged cerebral hemisphere combined with cathodal transcutaneous spinal direct current stimulation during robot-assisted gait training in chronic stroke patients. This is consistent with the neural organization of locomotion involving cortical and spinal control. The cerebellum is crucial for locomotor control, in particular for avoidance of obstacles, and adaptation to novel conditions during walking. Despite its key role in gait control, to date the effects of transcranial direct current stimulation of the cerebellum have not been investigated on brain stroke patients treated with robot-assisted gait training. To evaluate the effects of cerebellar transcranial direct current stimulation combined with transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke. After balanced randomization, 20 chronic stroke patients received ten, 20-minute robot-assisted gait training sessions (five days a week, for two consecutive weeks) combined with central nervous system stimulation. Group 1 underwent on-line cathodal transcranial direct current stimulation over the contralesional cerebellar hemisphere + cathodal transcutaneous spinal direct current stimulation. Group 2 received on-line anodal transcranial direct current stimulation over the damaged cerebral hemisphere + cathodal transcutaneous spinal direct current stimulation. The primary outcome was the 6-minute walk test performed before, after, and at follow-up at 2 and 4 weeks post-treatment. The significant differences in the 6-minute walk test noted between groups at the first post-treatment evaluation (p = 0.041) were not maintained at either the 2-week (P = 0.650) or the 4-week (P = 0.545) follow-up evaluations. Our preliminary findings support the hypothesis that cathodal transcranial direct current stimulation over the contralesional

Transcranial direct-current stimulation increases extracellular dopamine levels in the rat striatum

PubMed Central

Tanaka, Tomoko; Takano, Yuji; Tanaka, Satoshi; Hironaka, Naoyuki; Kobayashi, Kazuto; Hanakawa, Takashi; Watanabe, Katsumi; Honda, Manabu

2013-01-01

Background: Transcranial direct-current stimulation (tDCS) is a non-invasive procedure that achieves polarity-dependent modulation of neuronal membrane potentials. It has recently been used as a functional intervention technique for the treatment of psychiatric and neurological diseases; however, its neuronal mechanisms have not been fully investigated in vivo. Objective/Hypothesis: To investigate whether the application of cathodal or anodal tDCS affects extracellular dopamine and serotonin levels in the rat striatum. Methods: Stimulation and in vivo microdialysis were carried out under urethane anesthesia, and microdialysis probes were slowly inserted into the striatum. After the collection of baseline fractions in the rat striatum, cathodal or anodal tDCS was applied continuously for 10 min with a current intensity of 800 μA from an electrode placed on the skin of the scalp. Dialysis samples were collected every 10 min until at least 400 min after the onset of stimulation. Results: Following the application of cathodal, but not anodal, tDCS for 10 min, extracellular dopamine levels increased for more than 400 min in the striatum. There were no significant changes in extracellular serotonin levels. Conclusion: These findings suggest that tDCS has a direct and/or indirect effect on the dopaminergic system in the rat basal ganglia. PMID:23596399

Mechanisms and Effects of Transcranial Direct Current Stimulation

PubMed Central

Giordano, James; Bikson, Marom; Kappenman, Emily S.; Clark, Vincent P.; Coslett, H. Branch; Hamblin, Michael R.; Hamilton, Roy; Jankord, Ryan; Kozumbo, Walter J.; McKinley, R. Andrew; Nitsche, Michael A.; Reilly, J. Patrick; Richardson, Jessica; Wurzman, Rachel

2017-01-01

The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged. PMID:28210202

Anodal Transcranial Direct Current Stimulation Enhances Survival and Integration of Dopaminergic Cell Transplants in a Rat Parkinson Model

PubMed Central

Winkler, Christian; Reis, Janine; Hoffmann, Nadin; Gellner, Anne-Kathrin; Münkel, Christian; Curado, Marco Rocha

2017-01-01

Abstract Restorative therapy concepts, such as cell based therapies aim to restitute impaired neurotransmission in neurodegenerative diseases. New strategies to enhance grafted cell survival and integration are still needed to improve functional recovery. Anodal direct current stimulation (DCS) promotes neuronal activity and secretion of the trophic factor BDNF in the motor cortex. Transcranial DCS applied to the motor cortex transiently improves motor symptoms in Parkinson’s disease (PD) patients. In this proof-of-concept study, we combine cell based therapy and noninvasive neuromodulation to assess whether neurotrophic support via transcranial DCS would enhance the restitution of striatal neurotransmission by fetal dopaminergic transplants in a rat Parkinson model. Transcranial DCS was applied daily for 20 min on 14 consecutive days following striatal transplantation of fetal ventral mesencephalic (fVM) cells derived from transgenic rat embryos ubiquitously expressing GFP. Anodal but not cathodal transcranial DCS significantly enhanced graft survival and dopaminergic reinnervation of the surrounding striatal tissue relative to sham stimulation. Behavioral recovery was more pronounced following anodal transcranial DCS, and behavioral effects correlated with the degree of striatal innervation. Our results suggest anodal transcranial DCS may help advance cell-based restorative therapies in neurodegenerative diseases. In particular, such an assistive approach may be beneficial for the already established cell transplantation therapy in PD. PMID:28966974

Anodal Transcranial Direct Current Stimulation Enhances Survival and Integration of Dopaminergic Cell Transplants in a Rat Parkinson Model.

PubMed

Winkler, Christian; Reis, Janine; Hoffmann, Nadin; Gellner, Anne-Kathrin; Münkel, Christian; Curado, Marco Rocha; Furlanetti, Luciano; Garcia, Joanna; Döbrössy, Máté D; Fritsch, Brita

2017-01-01

Restorative therapy concepts, such as cell based therapies aim to restitute impaired neurotransmission in neurodegenerative diseases. New strategies to enhance grafted cell survival and integration are still needed to improve functional recovery. Anodal direct current stimulation (DCS) promotes neuronal activity and secretion of the trophic factor BDNF in the motor cortex. Transcranial DCS applied to the motor cortex transiently improves motor symptoms in Parkinson's disease (PD) patients. In this proof-of-concept study, we combine cell based therapy and noninvasive neuromodulation to assess whether neurotrophic support via transcranial DCS would enhance the restitution of striatal neurotransmission by fetal dopaminergic transplants in a rat Parkinson model. Transcranial DCS was applied daily for 20 min on 14 consecutive days following striatal transplantation of fetal ventral mesencephalic (fVM) cells derived from transgenic rat embryos ubiquitously expressing GFP. Anodal but not cathodal transcranial DCS significantly enhanced graft survival and dopaminergic reinnervation of the surrounding striatal tissue relative to sham stimulation. Behavioral recovery was more pronounced following anodal transcranial DCS, and behavioral effects correlated with the degree of striatal innervation. Our results suggest anodal transcranial DCS may help advance cell-based restorative therapies in neurodegenerative diseases. In particular, such an assistive approach may be beneficial for the already established cell transplantation therapy in PD.

Slow oscillating transcranial direct current stimulation during sleep has a sleep-stabilizing effect in chronic insomnia: a pilot study.

PubMed

Saebipour, Mohammad R; Joghataei, Mohammad T; Yoonessi, Ali; Sadeghniiat-Haghighi, Khosro; Khalighinejad, Nima; Khademi, Soroush

2015-10-01

Recent evidence suggests that lack of slow-wave activity may play a fundamental role in the pathogenesis of insomnia. Pharmacological approaches and brain stimulation techniques have recently offered solutions for increasing slow-wave activity during sleep. We used slow (0.75 Hz) oscillatory transcranial direct current stimulation during stage 2 of non-rapid eye movement sleeping insomnia patients for resonating their brain waves to the frequency of sleep slow-wave. Six patients diagnosed with either sleep maintenance or non-restorative sleep insomnia entered the study. After 1 night of adaptation and 1 night of baseline polysomnography, patients randomly received sham or real stimulation on the third and fourth night of the experiment. Our preliminary results show that after termination of stimulations (sham or real), slow oscillatory transcranial direct current stimulation increased the duration of stage 3 of non-rapid eye movement sleep by 33 ± 26 min (P = 0.026), and decreased stage 1 of non-rapid eye movement sleep duration by 22 ± 17.7 min (P = 0.028), compared with sham. Slow oscillatory transcranial direct current stimulation decreased stage 1 of non-rapid eye movement sleep and wake time after sleep-onset durations, together, by 55.4 ± 51 min (P = 0.045). Slow oscillatory transcranial direct current stimulation also increased sleep efficiency by 9 ± 7% (P = 0.026), and probability of transition from stage 2 to stage 3 of non-rapid eye movement sleep by 20 ± 17.8% (P = 0.04). Meanwhile, slow oscillatory transcranial direct current stimulation decreased transitions from stage 2 of non-rapid eye movement sleep to wake by 12 ± 6.7% (P = 0.007). Our preliminary results suggest a sleep-stabilizing role for the intervention, which may mimic the effect of sleep slow-wave-enhancing drugs. © 2015 European Sleep Research Society.

Improving Naming Abilities among Healthy Young-Old Adults Using Transcranial Direct Current Stimulation

ERIC Educational Resources Information Center

Lifshitz-Ben-Basat, Adi; Mashal, Nira

2018-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive tool to facilitate brain plasticity and enhance language abilities. Our study aims to search for a potential beneficial influence of tDCS on a cognitive linguistic task of naming which found to decline during aging. A group of fifteen healthy old adults (M = 64.93 ± 5.09 years) were…

Efficacy of transcranial direct current stimulation (tDCS) in reducing consumption in patients with alcohol use disorders: study protocol for a randomized controlled trial.

PubMed

Trojak, Benoit; Soudry-Faure, Agnès; Abello, Nicolas; Carpentier, Maud; Jonval, Lysiane; Allard, Coralie; Sabsevari, Foroogh; Blaise, Emilie; Ponavoy, Eddy; Bonin, Bernard; Meille, Vincent; Chauvet-Gelinier, Jean-Christophe

2016-05-17

Approximately 15 million persons in the European Union and 10 million persons in the USA are alcohol-dependent. The global burden of disease and injury attributable to alcohol is considerable: worldwide, approximately one in 25 deaths in 2004 was caused by alcohol. At the same time, alcohol use disorders remain seriously undertreated. In this context, alternative or adjunctive therapies such as brain stimulation may play a prominent role. The early results of studies using transcranial direct current stimulation found that stimulations delivered to the dorsolateral prefrontal cortex result in a significant reduction of craving and an improvement of the decision-making processes in various additive disorders. We, therefore, hypothesize that transcranial direct current stimulation can lead to a decrease in alcohol consumption in patients suffering from alcohol use disorders. We report the protocol of a randomized, double-blind, placebo-controlled, parallel-group trial, to evaluate the efficacy of transcranial direct current stimulation on alcohol reduction in patients with an alcohol use disorder. The study will be conducted in 14 centers in France and Monaco. Altogether, 340 subjects over 18 years of age and diagnosed with an alcohol use disorder will be randomized to receive five consecutive twice-daily sessions of either active or placebo transcranial direct current stimulation. One session consists in delivering a current flow continuously (anode F4; cathode F3) twice for 13 minutes, with treatments separated by a rest interval of 20 min. Efficacy will be evaluated using the change from baseline (alcohol consumption during the 4 weeks before randomization) to 24 weeks in the total alcohol consumption and number of heavy drinking days. Secondary outcome measures will include alcohol craving, clinical and biological improvements, and the effects on mood and quality of life, as well as cognitive and safety assessments, and, for smokers, an assessment of the

Transcranial direct current stimulation (tDCS) for treatment of major depression during pregnancy: study protocol for a pilot randomized controlled trial.

PubMed

Vigod, Simone; Dennis, Cindy-Lee; Daskalakis, Zafiris; Murphy, Kellie; Ray, Joel; Oberlander, Tim; Somerton, Sarah; Hussain-Shamsy, Neesha; Blumberger, Daniel

2014-09-18

Women with depression in pregnancy are faced with difficult treatment decisions. Untreated, antenatal depression has serious negative implications for mothers and children. While antidepressant drug treatment is likely to improve depressive symptoms, it crosses the placenta and may pose risks to the unborn child. Transcranial direct current stimulation is a focal brain stimulation treatment that improves depressive symptoms within 3 weeks of treatment by inducing changes to brain areas involved in depression, without impacting any other brain areas, and without inducing changes to heart rate, blood pressure or core body temperature. The localized nature of transcranial direct current stimulation makes it an ideal therapeutic approach for treating depression during pregnancy, although it has never previously been evaluated in this population. We describe a pilot randomized controlled trial of transcranial direct current stimulation among women with depression in pregnancy to assess the feasibility of a larger, multicentre efficacy study. Women over 18 years of age and between 14 and 32 weeks gestation can be enrolled in the study provided they meet diagnostic criteria for a major depressive episode of at least moderate severity and have been offered but refused antidepressant medication. Participants are randomized to receive active transcranial direct current stimulation or a sham condition that is administered in 15 30-minute treatments over three weeks. Women sit upright during treatment and receive obstetrical monitoring prior to, during and after each treatment session. Depressive symptoms, treatment acceptability, and pregnancy outcomes are assessed at baseline (prior to randomization), at the end of each treatment week, every four weeks post-treatment until delivery, and at 4 and 12 weeks postpartum. Transcranial direct current stimulation is a novel therapeutic option for treating depression during pregnancy. This protocol allows for assessment of the

Transcranial direct current stimulation (tDCS) and language

PubMed Central

Monti, Alessia; Ferrucci, Roberta; Fumagalli, Manuela; Mameli, Francesca; Cogiamanian, Filippo; Ardolino, Gianluca; Priori, Alberto

2013-01-01

Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique inducing prolonged brain excitability changes and promoting cerebral plasticity, is a promising option for neurorehabilitation. Here, we review progress in research on tDCS and language functions and on the potential role of tDCS in the treatment of post-stroke aphasia. Currently available data suggest that tDCS over language-related brain areas can modulate linguistic abilities in healthy individuals and can improve language performance in patients with aphasia. Whether the results obtained in experimental conditions are functionally important for the quality of life of patients and their caregivers remains unclear. Despite the fact that important variables are yet to be determined, tDCS combined with rehabilitation techniques seems a promising therapeutic option for aphasia. PMID:23138766

Effects of transcranial direct current stimulation on esophageal motility in patients with gastroesophageal reflux disease.

PubMed

Vigneri, Simone; Bonventre, Sebastiano; Inviati, Angela; Schifano, Domenico; Cosentino, Giuseppe; Puma, Angela; Giglia, Giuseppe; Paladino, Piera; Brighina, Filippo; Fierro, Brigida

2014-09-01

To evaluate the effects of transcranial direct current stimulation (tDCS) on esophageal peristalsis in patients with gastroesophageal reflux disease (GERD). Patients with GERD preliminary diagnosis were included in a randomized double-blind sham-controlled study. Esophageal manometry was performed before and during transcranial direct current stimulation (tDCS) of the right precentral cortex. Half of patients were randomly assigned to anodal, half to sham stimulation. Distal waves amplitude and pathological waves percentage were measured, after swallowing water boli, for ten subsequent times. Last, a 24h pH-bilimetry was done to diagnose non-erosive reflux disease (NERD) or functional heartburn (FH). The values obtained before and during anodal or sham tDCS were compared. Sixty-eight patients were enrolled in the study. Distal waves mean amplitude increased significantly only during anodal tDCS in NERD (p=0.00002) and FH subgroups (p=0.008) while percentage of pathological waves strongly decreased only in NERDs (p=0.002). Transcranial stimulation can influence cortical control of esophageal motility and improve pathological motor pattern in NERD and FH but not in erosive reflux disease (ERD) patients. Pathophysiological processes in GERD are not only due to peripheral damage but to central neural control involvement as well. In ERD patients dysfunctions of the cortico-esophageal circuit seem to be more severe and may affect central nervous system physiology. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Effects of Transcranial Direct Current Stimulation (tDCS) on Behaviour and Electrophysiology of Language Production

ERIC Educational Resources Information Center

Wirth, Miranka; Rahman, Rasha Abdel; Kuenecke, Janina; Koenig, Thomas; Horn, Helge; Sommer, Werner; Dierks, Thomas

2011-01-01

Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left dorsal prefrontal cortex (DPFC) has been shown to improve language production. The present study examined neurophysiological underpinnings of this effect. In a single-blinded within-subject design, we traced effects of A-tDCS compared to sham stimulation over the left…

Novel methods to optimize the effects of transcranial direct current stimulation: a systematic review of transcranial direct current stimulation patents.

PubMed

Malavera, Alejandra; Vasquez, Alejandra; Fregni, Felipe

2015-01-01

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that has been extensively studied. While there have been initial positive results in some clinical trials, there is still variability in tDCS results. The aim of this article is to review and discuss patents assessing novel methods to optimize the use of tDCS. A systematic review was performed using Google patents database with tDCS as the main technique, with patents filling date between 2010 and 2015. Twenty-two patents met our inclusion criteria. These patents attempt to address current tDCS limitations. Only a few of them have been investigated in clinical trials (i.e., high-definition tDCS), and indeed most of them have not been tested before in human trials. Further clinical testing is required to assess which patents are more likely to optimize the effects of tDCS. We discuss the potential optimization of tDCS based on these patents and the current experience with standard tDCS.

Transcranial direct-current stimulation as treatment in epilepsy.

PubMed

Gschwind, Markus; Seeck, Margitta

2016-12-01

Neuromodulation (NM) is a complementary therapy for patients with drug-resistant epilepsy. Vagal nerve stimulation and deep brain stimulation of the anterior thalamus are established techniques and have shown their efficacy in lowering seizure frequency, but they are invasive and rarely render patients seizure-free. Non-invasive NM techniques are therefore increasingly investigated in a clinical context. Areas covered: Current knowledge about transcranial direct-current stimulation (tDCS) and other non-invasive NM in patients with epilepsy, based on the available animal and clinical studies from PubMed search. Expert commentary: tDCS modulates neuronal membrane potentials, and consequently alters cortical excitability. Cathodal stimulation leads to cortical inhibition, which is of particular importance in epilepsy treatment. The antiepileptic efficacy is promising but still lacks systematic studies. The beneficial effect, seen in ~20%, outlasts the duration of stimulation, indicating neuronal plasticity and is therefore of great interest to obtain long-term effects.

An Automated Method for High-Definition Transcranial Direct Current Stimulation Modeling*

PubMed Central

Huang, Yu; Su, Yuzhuo; Rorden, Christopher; Dmochowski, Jacek; Datta, Abhishek; Parra, Lucas C.

2014-01-01

Targeted transcranial stimulation with electric currents requires accurate models of the current flow from scalp electrodes to the human brain. Idiosyncratic anatomy of individual brains and heads leads to significant variability in such current flows across subjects, thus, necessitating accurate individualized head models. Here we report on an automated processing chain that computes current distributions in the head starting from a structural magnetic resonance image (MRI). The main purpose of automating this process is to reduce the substantial effort currently required for manual segmentation, electrode placement, and solving of finite element models. In doing so, several weeks of manual labor were reduced to no more than 4 hours of computation time and minimal user interaction, while current-flow results for the automated method deviated by less than 27.9% from the manual method. Key facilitating factors are the addition of three tissue types (skull, scalp and air) to a state-of-the-art automated segmentation process, morphological processing to correct small but important segmentation errors, and automated placement of small electrodes based on easily reproducible standard electrode configurations. We anticipate that such an automated processing will become an indispensable tool to individualize transcranial direct current stimulation (tDCS) therapy. PMID:23367144

The added value of auditory cortex transcranial random noise stimulation (tRNS) after bifrontal transcranial direct current stimulation (tDCS) for tinnitus.

PubMed

To, Wing Ting; Ost, Jan; Hart, John; De Ridder, Dirk; Vanneste, Sven

2017-01-01

Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Research has suggested that functional abnormalities in tinnitus patients involve auditory as well as non-auditory brain areas. Transcranial electrical stimulation (tES), such as transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex and transcranial random noise stimulation (tRNS) to the auditory cortex, has demonstrated modulation of brain activity to transiently suppress tinnitus symptoms. Targeting two core regions of the tinnitus network by tES might establish a promising strategy to enhance treatment effects. This proof-of-concept study aims to investigate the effect of a multisite tES treatment protocol on tinnitus intensity and distress. A total of 40 tinnitus patients were enrolled in this study and received either bifrontal tDCS or the multisite treatment of bifrontal tDCS before bilateral auditory cortex tRNS. Both groups were treated on eight sessions (two times a week for 4 weeks). Our results show that a multisite treatment protocol resulted in more pronounced effects when compared with the bifrontal tDCS protocol or the waiting list group, suggesting an added value of auditory cortex tRNS to the bifrontal tDCS protocol for tinnitus patients. These findings support the involvement of the auditory as well as non-auditory brain areas in the pathophysiology of tinnitus and demonstrate the idea of the efficacy of network stimulation in the treatment of neurological disorders. This multisite tES treatment protocol proved to be save and feasible for clinical routine in tinnitus patients.

Anodal transcranial direct current stimulation of right temporoparietal area inhibits self-recognition.

PubMed

Payne, Sophie; Tsakiris, Manos

2017-02-01

Self-other discrimination is a crucial mechanism for social cognition. Neuroimaging and neurostimulation research has pointed to the involvement of the right temporoparietal region in a variety of self-other discrimination tasks. Although repetitive transcranial magnetic stimulation over the right temporoparietal area has been shown to disrupt self-other discrimination in face-recognition tasks, no research has investigated the effect of increasing the cortical excitability in this region on self-other face discrimination. Here we used transcranial direct current stimulation (tDCS) to investigate changes in self-other discrimination with a video-morphing task in which the participant's face morphed into, or out of, a familiar other's face. The task was performed before and after 20 min of tDCS targeting the right temporoparietal area (anodal, cathodal, or sham stimulation). Differences in task performance following stimulation were taken to indicate a change in self-other discrimination. Following anodal stimulation only, we observed a significant increase in the amount of self-face needed to distinguish between self and other. The findings are discussed in relation to the control of self and other representations and to domain-general theories of social cognition.

Preliminary Evidence That Excitatory Transcranial Direct Current Stimulation Extends Time to Task Failure of a Sustained, Submaximal Muscular Contraction in Older Adults.

PubMed

Oki, Kentaro; Mahato, Niladri K; Nakazawa, Masato; Amano, Shinichi; France, Christopher R; Russ, David W; Clark, Brian C

2016-08-01

Decreased cortical excitability has been proposed as a potential mechanism underlying task failure during sustained muscular contractions, and cortical excitability may decrease with old age. We tested the hypothesis that transcranial direct current stimulation, which has been reported to raise cortical excitability, would prolong the time to task failure during a sustained muscular contraction in older adults. Thirteen older adults (68.3±2.0 years; eight women and five men) performed isometric, elbow flexions to failure while receiving sham or anodal transcranial direct current stimulation. Order of stimulation was randomized, and the subjects and investigators were blinded to condition. Time to task failure was measured alongside selected psychological indices of perceived exertion and affect. Anodal transcranial direct current stimulation prolonged mean time to task failure by approximately 15% (16.9±2.2 vs 14.7±1.8 minutes) and slowed the rate of increase in rating of perceived exertion (0.29±0.03 vs 0.31±0.03) relative to the sham condition. These preliminary findings suggest that anodal transcranial direct current stimulation enhances time to task failure of a sustained, submaximal contraction in older adults by potentially increasing cortical excitability and/or influencing the perception of exertion. These results raise the question of whether interventions that acutely increase cortical excitability could enhance physical function and/or exercise-induced adaptations in older adults. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effect of transcranial direct current stimulation combined with gait and mobility training on functionality in children with cerebral palsy: study protocol for a double-blind randomized controlled clinical trial

PubMed Central

2013-01-01

Background The project proposes three innovative intervention techniques (treadmill training, mobility training with virtual reality and transcranial direct current stimulation that can be safely administered to children with cerebral palsy. The combination of transcranial stimulation and physical therapy resources will provide the training of a specific task with multiple rhythmic repetitions of the phases of the gait cycle, providing rich sensory stimuli with a modified excitability threshold of the primary motor cortex to enhance local synaptic efficacy and potentiate motor learning. Methods/design A prospective, double-blind, randomized, controlled, analytical, clinical trial will be carried out.Eligible participants will be children with cerebral palsy classified on levels I, II and III of the Gross Motor Function Classification System between four and ten years of age. The participants will be randomly allocated to four groups: 1) gait training on a treadmill with placebo transcranial stimulation; 2) gait training on a treadmill with active transcranial stimulation; 3) mobility training with virtual reality and placebo transcranial stimulation; 4) mobility training with virtual reality and active transcranial stimulation. Transcranial direct current stimulation will be applied with the anodal electrode positioned in the region of the dominant hemisphere over C3, corresponding to the primary motor cortex, and the cathode positioned in the supraorbital region contralateral to the anode. A 1 mA current will be applied for 20 minutes. Treadmill training and mobility training with virtual reality will be performed in 30-minute sessions five times a week for two weeks (total of 10 sessions). Evaluations will be performed on four occasions: one week prior to the intervention; one week following the intervention; one month after the end of the intervention;and 3 months after the end of the intervention. The evaluations will involve three-dimensional gait analysis

ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) INCREASES ISOMETRIC STRENGTH OF SHOULDER ROTATORS MUSCLES IN HANDBALL PLAYERS.

PubMed

Hazime, Fuad Ahmad; da Cunha, Ronaldo Alves; Soliaman, Renato Rozenblit; Romancini, Ana Clara Bezerra; Pochini, Alberto de Castro; Ejnisman, Benno; Baptista, Abrahão Fontes

2017-06-01

Weakness of the rotator cuff muscles can lead to imbalances in the strength of shoulder external and internal rotators, change the biomechanics of the glenohumeral joint and predispose an athlete to injury. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has demonstrated promising results in a variety of health conditions. However few studies addressed its potential approach in the realm of athletics. The purpose of this study was to investigate if transcranial direct current stimulation (tDCS) technique increases the isometric muscle strength of shoulder external and internal rotators in handball athletes. Randomized, double-blind, placebo-controlled, crossover study. Eight female handball players aged between 17 and 21 years (Mean=19.65; SD=2.55) with 7.1 ± 4.8 years of experience in training, participating in regional and national competitions were recruited. Maximal voluntary isometric contraction (MVIC) of shoulder external and internal rotator muscles was evaluated during and after 30 and 60 minutes post one session of anodal and sham current (2mA; 0.057mA/cm 2 ) with a one-week interval between stimulations. Compared to baseline, MVIC of shoulder external and internal rotators significantly increased after real but not sham tDCS. Between-group differences were observed for external and internal rotator muscles. Maximal voluntary isometric contraction of external rotation increased significantly during tDCS, and 30 and 60 minutes post-tDCS for real tDCS compared to that for sham tDCS. For internal rotation MVIC increased significantly during and 60 minutes post-tDCS. The results indicate that transcranial direct current stimulation temporarily increases maximal isometric contractions of the internal and external rotators of the shoulder in handball players. 2.

Transcranial direct current stimulation in psychiatric disorders

PubMed Central

Tortella, Gabriel; Casati, Roberta; Aparicio, Luana V M; Mantovani, Antonio; Senço, Natasha; D’Urso, Giordano; Brunelin, Jerome; Guarienti, Fabiana; Selingardi, Priscila Mara Lorencini; Muszkat, Débora; Junior, Bernardo de Sampaio Pereira; Valiengo, Leandro; Moffa, Adriano H; Simis, Marcel; Borrione, Lucas; Brunoni, André R

2015-01-01

The interest in non-invasive brain stimulation techniques is increasing in recent years. Among these techniques, transcranial direct current stimulation (tDCS) has been the subject of great interest among researchers because of its easiness to use, low cost, benign profile of side effects and encouraging results of research in the field. This interest has generated several studies and randomized clinical trials, particularly in psychiatry. In this review, we provide a summary of the development of the technique and its mechanism of action as well as a review of the methodological aspects of randomized clinical trials in psychiatry, including studies in affective disorders, schizophrenia, obsessive compulsive disorder, child psychiatry and substance use disorder. Finally, we provide an overview of tDCS use in cognitive enhancement as well as a discussion regarding its clinical use and regulatory and ethical issues. Although many promising results regarding tDCS efficacy were described, the total number of studies is still low, highlighting the need of further studies aiming to replicate these findings in larger samples as to provide a definite picture regarding tDCS efficacy in psychiatry. PMID:25815258

Animal models of transcranial direct current stimulation: Methods and mechanisms.

PubMed

Jackson, Mark P; Rahman, Asif; Lafon, Belen; Kronberg, Gregory; Ling, Doris; Parra, Lucas C; Bikson, Marom

2016-11-01

The objective of this review is to summarize the contribution of animal research using direct current stimulation (DCS) to our understanding of the physiological effects of transcranial direct current stimulation (tDCS). We comprehensively address experimental methodology in animal studies, broadly classified as: (1) transcranial stimulation; (2) direct cortical stimulation in vivo and (3) in vitro models. In each case advantages and disadvantages for translational research are discussed including dose translation and the overarching "quasi-uniform" assumption, which underpins translational relevance in all animal models of tDCS. Terminology such as anode, cathode, inward current, outward current, current density, electric field, and uniform are defined. Though we put key animal experiments spanning decades in perspective, our goal is not simply an exhaustive cataloging of relevant animal studies, but rather to put them in context of ongoing efforts to improve tDCS. Cellular targets, including excitatory neuronal somas, dendrites, axons, interneurons, glial cells, and endothelial cells are considered. We emphasize neurons are always depolarized and hyperpolarized such that effects of DCS on neuronal excitability can only be evaluated within subcellular regions of the neuron. Findings from animal studies on the effects of DCS on plasticity (LTP/LTD) and network oscillations are reviewed extensively. Any endogenous phenomena dependent on membrane potential changes are, in theory, susceptible to modulation by DCS. The relevance of morphological changes (galvanotropy) to tDCS is also considered, as we suggest microscopic migration of axon terminals or dendritic spines may be relevant during tDCS. A majority of clinical studies using tDCS employ a simplistic dose strategy where excitability is singularly increased or decreased under the anode and cathode, respectively. We discuss how this strategy, itself based on classic animal studies, cannot account for the

Animal Models of transcranial Direct Current Stimulation: Methods and Mechanisms

PubMed Central

Jackson, Mark P.; Rahman, Asif; Lafon, Belen; Kronberg, Gregory; Ling, Doris; Parra, Lucas C.; Bikson, Marom

2016-01-01

The objective of this review is to summarize the contribution of animal research using direct current stimulation (DCS) to our understanding of the physiological effects of transcranial direct current stimulation (tDCS). We comprehensively address experimental methodology in animal studies, broadly classified as: 1) transcranial stimulation; 2) direct cortical stimulation in vivo and 3) in vitro models. In each case advantages and disadvantages for translational research are discussed including dose translation and the overarching “quasi-uniform” assumption, which underpins translational relevance in all animal models of tDCS. Terminology such as anode, cathode, inward current, outward current, current density, electric field, and uniform are defined. Though we put key animal experiments spanning decades in perspective, our goal is not simply an exhaustive cataloging of relevant animal studies, but rather to put them in context of ongoing efforts to improve tDCS. Cellular targets, including excitatory neuronal somas, dendrites, axons, interneurons, glial cells, and endothelial cells are considered. We emphasize neurons are always depolarized and hyperpolarized such that effects of DCS on neuronal excitability can only be evaluated within subcellular regions of the neuron. Findings from animal studies on the effects of DCS on plasticity (LTP/LTD) and network oscillations are reviewed extensively. Any endogenous phenomena dependent on membrane potential changes are, in theory, susceptible to modulation by DCS. The relevance of morphological changes (galvanotropy) to tDCS is also considered, as we suggest microscopic migration of axon terminals or dendritic spines may be relevant during tDCS. A majority of clinical studies using tDCS employ a simplistic dose strategy where excitability is singularly increased or decreased under the anode and cathode, respectively. We discuss how this strategy, itself based on classic animal studies, cannot account for the

Influence of Concurrent Finger Movements on Transcranial Direct Current Stimulation (tDCS)-Induced Aftereffects.

PubMed

Shirota, Yuichiro; Terney, Daniella; Antal, Andrea; Paulus, Walter

2017-01-01

Transcranial direct current stimulation (tDCS) has been reported to have bidirectional influence on the amplitude of motor-evoked potentials (MEPs) in resting participants in a polarity-specific manner: anodal tDCS increased and cathodal tDCS decreased them. More recently, the effects of tDCS have been shown to depend on a number of additional factors. We investigated whether a small variety of movements involving target and non-target muscles could differentially modify the efficacy of tDCS. MEPs were elicited from the right first dorsal interosseous muscle, defined as the target muscle, by single pulse transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). During M1 tDCS, which lasted for 10 min applying anodal, cathodal, or sham condition, the participants were instructed to squeeze a ball with their right hand (Task 1), to move their right index finger only in the medial (Task 2), in the lateral direction (Task 3), or in medial and lateral direction alternatively (Task 4). Anodal tDCS reduced MEP amplitudes measured in Task 1 and Task 2, but to a lesser extent in the latter. In Task 3, anodal tDCS led to greater MEP amplitudes than cathodal stimulation. Alternating movements resulted in no effect of tDCS on MEP amplitude (Task 4). The results are congruent with the current notion that the aftereffects of tDCS are highly variable relying on a number of factors including the type of movements executed during stimulation.

Cellular and Molecular Mechanisms of Action of Transcranial Direct Current Stimulation: Evidence from In Vitro and In Vivo Models

PubMed Central

Pelletier, Simon J.

2015-01-01

Transcranial direct current stimulation is a noninvasive technique that has been experimentally tested for a number of psychiatric and neurological conditions. Preliminary observations suggest that this approach can indeed influence a number of cellular and molecular pathways that may be disease relevant. However, the mechanisms of action underlying its beneficial effects are largely unknown and need to be better understood to allow this therapy to be used optimally. In this review, we summarize the physiological responses observed in vitro and in vivo, with a particular emphasis on cellular and molecular cascades associated with inflammation, angiogenesis, neurogenesis, and neuroplasticity recruited by direct current stimulation, a topic that has been largely neglected in the literature. A better understanding of the neural responses to transcranial direct current stimulation is critical if this therapy is to be used in large-scale clinical trials with a view of being routinely offered to patients suffering from various conditions affecting the central nervous system. PMID:25522391

Contribution of Transcranial Direct Current Stimulation on Inhibitory Control to Assess the Neurobiological Aspects of Attention Deficit Hyperactivity Disorder: Randomized Controlled Trial

PubMed Central

Baptista, Abrahão Fontes; de Sena, Eduardo Pondé

2015-01-01

Background The applicability of transcranial direct current stimulation (tDCS) in individuals with attention deficit hyperactivity disorder (ADHD) has not yet been investigated. This low-cost, non-invasive, and safe technique optimized to modulate the inhibitory response might be a useful treatment option for those affected by this condition. Objective The aim of this single center, parallel, randomized, double-blinded, sham-controlled trial is to investigate the efficacy of transcranial direct current stimulation over the prefrontal cortex on the modulation of inhibitory control in adults with attention deficit hyperactivity disorder. Methods A total of 60 individuals will be divided into 2 groups by block randomization to receive active or sham stimulation. Anodal stimulation over the left dorsolateral prefrontal cortex will be applied at 1 mA during a single 20-minute session. Before and after interventions, subjects will perform 2 go/no go tasks and the brain electrical activity will be recorded by electroencephalogram (EEG) with 32 channels, according to the 10-20 international EEG system. Results The trial began in May 2013 and we are currently performing the statistical analysis for the secondary outcomes. Conclusions The findings from this study will provide preliminary results about the role of prefrontal cortex activation through tDCS on ADHD patients. Trial Registration Clinicaltrials.gov NCT01968512; http://clinicaltrials.gov/ct2/show/NCT01968512 (Archived by WebCite at www.webcitation.org/6YMSW2tkD). PMID:25986784

Transcranial direct current stimulation improves neurorehabilitation of task-specific dystonia: a pilot study.

PubMed

Rosset-Llobet, Jaume; Fàbregas-Molas, Sílvia; Pascual-Leone, Alvaro

2014-03-01

Sensory-motor returning (SMR) can help the symptoms of task-specific focal hand dystonia. However, effects vary across patients and take many sessions. Here, we present proof of principle evidence that transcranial direct current stimulation (tDCS) can enhance these effects. We compared the effects of a combined tDCS-SMR protocol (n=4 patients) with the efficacy of SMR alone (n=30 patients). All 4 patients treated with the combined protocol showed greater improvement than those undergoing SMR alone. Results encourage a larger, parallel-group clinical trial with sham tDCS control.

Effect of Transcranial Direct Current Stimulation in Patients With Tinnitus: A Meta-Analysis and Systematic Review.

PubMed

Wang, Tang-Chuan; Tyler, Richard S; Chang, Ta-Yuan; Chen, Jui-Cheng; Lin, Chia-Der; Chung, Hsiung-Kwang; Tsou, Yung-An

2018-02-01

Subjective tinnitus is a phantom sensation experienced without any external source of sound that profoundly impacts the quality of life. Some investigations have claimed that transcranial direct current stimulation (tDCS) reduces tinnitus, but studies on tDCS have demonstrated variable results. This meta-analysis aimed to examine the effect of tDCS on patients with tinnitus. We searched for articles published through January 5, 2016, in Medline, Cochrane, EMBASE, and Google Scholar using the following keywords: tinnitus, transcranial direct current stimulation, and tDCS. The study outcomes were change in magnitude estimates of loudness (loudness), tinnitus-related distress (distress), and Tinnitus Handicap Inventory (THI). Pooled results demonstrated that tDCS did not have a beneficial effect on loudness (pooled standardized difference in means = 0.674, 95% CI, -0.089 to 1.437, P = .083). Further, the pooled results demonstrated a greater reduction in distress for the tDCS group (pooled standardized difference in means = 0.634, 95% CI, 0.021-1.247, P = .043). We conclude that the pooled results demonstrated a greater reduction in distress for groups treated with tDCS as compared with those administered a sham treatment.

Effectiveness of transcranial direct current stimulation preceding cognitive behavioural management for chronic low back pain: sham controlled double blinded randomised controlled trial.

PubMed

Luedtke, Kerstin; Rushton, Alison; Wright, Christine; Jürgens, Tim; Polzer, Astrid; Mueller, Gerd; May, Arne

2015-04-16

To evaluate the effectiveness of transcranial direct current stimulation alone and in combination with cognitive behavioural management in patients with non-specific chronic low back pain. Double blind parallel group randomised controlled trial with six months' follow-up conducted May 2011-March 2013. Participants, physiotherapists, assessors, and analyses were blinded to group allocation. Interdisciplinary chronic pain centre. 135 participants with non-specific chronic low back pain >12 weeks were recruited from 225 patients assessed for eligibility. Participants were randomised to receive anodal (20 minutes to motor cortex at 2 mA) or sham transcranial direct current stimulation (identical electrode position, stimulator switched off after 30 seconds) for five consecutive days immediately before cognitive behavioural management (four week multidisciplinary programme of 80 hours). Two primary outcome measures of pain intensity (0-100 visual analogue scale) and disability (Oswestry disability index) were evaluated at two primary endpoints after stimulation and after cognitive behavioural management. Analyses of covariance with baseline values (pain or disability) as covariates showed that transcranial direct current stimulation was ineffective for the reduction of pain (difference between groups on visual analogue scale 1 mm (99% confidence interval -8.69 mm to 6.3 mm; P=0.68)) and disability (difference between groups 1 point (-1.73 to 1.98; P=0.86)) and did not influence the outcome of cognitive behavioural management (difference between group 3 mm (-10.32 mm to 6.73 mm); P=0.58; difference between groups on Oswestry disability index 0 point (-2.45 to 2.62); P=0.92). The stimulation was well tolerated with minimal transitory side effects. This results of this trial on the effectiveness of transcranial direct current stimulation for the reduction of pain and disability do not support its clinical use for managing non-specific chronic low back pain

Can Transcranial Direct Current Stimulation Augment Extinction of Conditioned Fear?

PubMed Central

van ’t Wout, Mascha; Mariano, Timothy Y.; Garnaat, Sarah L.; Reddy, Madhavi K.; Rasmussen, Steven A.; Greenberg, Benjamin D.

2016-01-01

Background Exposure-based therapy parallels extinction learning of conditioned fear. Prior research points to the ventromedial prefrontal cortex as a potential site for the consolidation of extinction learning and subsequent retention of extinction memory. Objective/hypothesis The present study aimed to evaluate whether the application of non-invasive transcranial direct current stimulation (tDCS) during extinction learning enhances late extinction and early recall in human participants. Methods Forty-four healthy volunteers completed a 2-day Pavlovian fear conditioning, extinction, and recall paradigm while skin conductance activity was continuously measured. Twenty-six participants received 2 mA anodal tDCS over EEG coordinate AF3 during extinction of a first conditioned stimulus. The remaining 18 participants received similar tDCS during extinction of a second conditioned stimulus. Sham stimulation was applied for the balance of extinction trials in both groups. Normalized skin conductance changes were analyzed using linear mixed models to evaluate effects of tDCS over late extinction and early recall trials. Results We observed a significant interaction between timing of tDCS during extinction blocks and changes in skin conductance reactivity over late extinction trials. These data indicate that tDCS was associated with accelerated late extinction learning of a second conditioned stimulus after tDCS was combined with extinction learning of a previous conditioned stimulus. No significant effects of tDCS timing were observed on early extinction recall. Conclusions Results could be explained by an anxiolytic aftereffect of tDCS and extend previous studies on tDCS-induced modulation of fear and threat related learning processes. These findings support further exploration of the clinical use of tDCS. PMID:27037186

Synergistic effect of combined transcranial direct current stimulation/constraint-induced movement therapy in children and young adults with hemiparesis: study protocol.

PubMed

Gillick, Bernadette; Menk, Jeremiah; Mueller, Bryon; Meekins, Gregg; Krach, Linda E; Feyma, Timothy; Rudser, Kyle

2015-11-12

Perinatal stroke occurs in more than 1 in 2,500 live births and resultant congenital hemiparesis necessitates investigation into interventions which may improve long-term function and decreased burden of care beyond current therapies ( http://www.cdc.gov/ncbddd/cp/data.html ). Constraint-Induced Movement Therapy (CIMT) is recognized as an effective hemiparesis rehabilitation intervention. Transcranial direct current stimulation as an adjunct treatment to CIMT may potentiate neuroplastic responses and improve motor function. The methodology of a clinical trial in children designed as a placebo-controlled, serial -session, non-invasive brain stimulation trial incorporating CIMT is described here. The primary hypotheses are 1) that no serious adverse events will occur in children receiving non-invasive brain stimulation and 2) that children in the stimulation intervention group will show significant improvements in hand motor function compared to children in the placebo stimulation control group. A randomized, controlled, double-blinded clinical trial. Twenty children and/or young adults (ages 8-21) with congenital hemiparesis, will be enrolled. The intervention group will receive ten 2-hour sessions of transcranial direct current stimulation combined with constraint-induced movement therapy and the control group will receive sham stimulation with CIMT. The primary outcome measure is safety assessment of transcranial direct current stimulation by physician evaluation, vital sign monitoring and symptom reports. Additionally, hand function will be evaluated using the Assisting Hand Assessment, grip strength and assessment of goals using the Canadian Occupational Performance Measure. Neuroimaging will confirm diagnoses, corticospinal tract integrity and cortical activation. Motor cortical excitability will also be examined using transcranial magnetic stimulation techniques. Combining non-invasive brain stimulation and CIMT interventions has the potential to improve motor

Anodal transcranial direct current stimulation of the motor cortex increases cortical voluntary activation and neural plasticity.

PubMed

Frazer, Ashlyn; Williams, Jacqueline; Spittles, Michael; Rantalainen, Timo; Kidgell, Dawson

2016-11-01

We examined the cumulative effect of 4 consecutive bouts of noninvasive brain stimulation on corticospinal plasticity and motor performance, and whether these responses were influenced by the brain-derived neurotrophic factor (BDNF) polymorphism. In a randomized double-blinded cross-over design, changes in strength and indices of corticospinal plasticity were analyzed in 14 adults who were exposed to 4 consecutive sessions of anodal and sham transcranial direct current stimulation (tDCS). Participants also undertook a blood sample for BDNF genotyping (N = 13). We observed a significant increase in isometric wrist flexor strength with transcranial magnetic stimulation revealing increased corticospinal excitability, decreased silent period duration, and increased cortical voluntary activation compared with sham tDCS. The results show that 4 consecutive sessions of anodal tDCS increased cortical voluntary activation manifested as an improvement in strength. Induction of corticospinal plasticity appears to be influenced by the BDNF polymorphism. Muscle Nerve 54: 903-913, 2016. © 2016 Wiley Periodicals, Inc.

Increasing propensity to mind-wander with transcranial direct current stimulation

PubMed Central

Axelrod, Vadim; Rees, Geraint; Lavidor, Michal; Bar, Moshe

2015-01-01

Humans mind-wander quite intensely. Mind wandering is markedly different from other cognitive behaviors because it is spontaneous, self-generated, and inwardly directed (inner thoughts). However, can such an internal and intimate mental function also be modulated externally by means of brain stimulation? Addressing this question could also help identify the neural correlates of mind wandering in a causal manner, in contrast to the correlational methods used previously (primarily functional MRI). In our study, participants performed a monotonous task while we periodically sampled their thoughts to assess mind wandering. Concurrently, we applied transcranial direct current stimulation (tDCS). We found that stimulation of the frontal lobes [anode electrode at the left dorsolateral prefrontal cortex (DLPFC), cathode electrode at the right supraorbital area], but not of the occipital cortex or sham stimulation, increased the propensity to mind-wander. These results demonstrate for the first time, to our knowledge, that mind wandering can be enhanced externally using brain stimulation, and that the frontal lobes play a causal role in mind-wandering behavior. These results also suggest that the executive control network associated with the DLPFC might be an integral part of mind-wandering neural machinery. PMID:25691738

Increasing propensity to mind-wander with transcranial direct current stimulation.

PubMed

Axelrod, Vadim; Rees, Geraint; Lavidor, Michal; Bar, Moshe

2015-03-17

Humans mind-wander quite intensely. Mind wandering is markedly different from other cognitive behaviors because it is spontaneous, self-generated, and inwardly directed (inner thoughts). However, can such an internal and intimate mental function also be modulated externally by means of brain stimulation? Addressing this question could also help identify the neural correlates of mind wandering in a causal manner, in contrast to the correlational methods used previously (primarily functional MRI). In our study, participants performed a monotonous task while we periodically sampled their thoughts to assess mind wandering. Concurrently, we applied transcranial direct current stimulation (tDCS). We found that stimulation of the frontal lobes [anode electrode at the left dorsolateral prefrontal cortex (DLPFC), cathode electrode at the right supraorbital area], but not of the occipital cortex or sham stimulation, increased the propensity to mind-wander. These results demonstrate for the first time, to our knowledge, that mind wandering can be enhanced externally using brain stimulation, and that the frontal lobes play a causal role in mind-wandering behavior. These results also suggest that the executive control network associated with the DLPFC might be an integral part of mind-wandering neural machinery.

The contribution of interindividual factors to variability of response in transcranial direct current stimulation studies

PubMed Central

Li, Lucia M.; Uehara, Kazumasa; Hanakawa, Takashi

2015-01-01

There has been an explosion of research using transcranial direct current stimulation (tDCS) for investigating and modulating human cognitive and motor function in healthy populations. It has also been used in many studies seeking to improve deficits in disease populations. With the slew of studies reporting “promising results” for everything from motor recovery after stroke to boosting memory function, one could be easily seduced by the idea of tDCS being the next panacea for all neurological ills. However, huge variability exists in the reported effects of tDCS, with great variability in the effect sizes and even contradictory results reported. In this review, we consider the interindividual factors that may contribute to this variability. In particular, we discuss the importance of baseline neuronal state and features, anatomy, age and the inherent variability in the injured brain. We additionally consider how interindividual variability affects the results of motor-evoked potential (MEP) testing with transcranial magnetic stimulation (TMS), which, in turn, can lead to apparent variability in response to tDCS in motor studies. PMID:26029052

Acute seizure suppression by transcranial direct current stimulation in rats

PubMed Central

Dhamne, Sameer C; Ekstein, Dana; Zhuo, Zhihong; Gersner, Roman; Zurakowski, David; Loddenkemper, Tobias; Pascual-Leone, Alvaro; Jensen, Frances E; Rotenberg, Alexander

2015-01-01

Objective Cathodal transcranial direct current stimulation (tDCS) is a focal neuromodulation technique that suppresses cortical excitability by low-amplitude constant electrical current, and may have an antiepileptic effect. Yet, tDCS has not been tested in status epilepticus (SE). Furthermore, a combined tDCS and pharmacotherapy antiseizure approach is unexplored. We therefore examined in the rat pentylenetetrazol (PTZ) SE model whether cathodal tDCS (1) suppresses seizures, (2) augments lorazepam (LZP) efficacy, and (3) enhances GABAergic cortical inhibition. Methods Experiment 1 aimed to identify an effective cathodal tDCS intensity. Rats received intraperitoneal PTZ followed by tDCS (sham, cathodal 1 mA, or cathodal 0.1 mA; for 20 min), and then a second PTZ challenge. In Experiment 2, two additional animal groups received a subtherapeutic LZP dose after PTZ, and then verum or sham tDCS. Clinical and electroencephalography (EEG) epileptic activity were compared between all groups. In Experiment 3, we measured GABA-mediated paired-pulse inhibition of the motor evoked potential by paired-pulse transcranial magnetic stimulation (ppTMS) in rats that received PTZ or saline, and either verum or sham tDCS. Results Cathodal 1 mA tDCS (1) reduced EEG spike bursts, and suppressed clinical seizures after the second PTZ challenge, (2) in combination with LZP was more effective in seizure suppression and improved the clinical seizure outcomes compared to either tDCS or LZP alone, and (3) prevented the loss of ppTMS motor cortex inhibition that accompanied PTZ injection. Interpretation These results suggest that cathodal 1 mA tDCS alone and in combination with LZP can suppress seizures by augmenting GABAergic cortical inhibition. PMID:26339678

Transcranial cerebellar direct current stimulation and transcutaneous spinal cord direct current stimulation as innovative tools for neuroscientists

PubMed Central

Priori, Alberto; Ciocca, Matteo; Parazzini, Marta; Vergari, Maurizio; Ferrucci, Roberta

2014-01-01

Two neuromodulatory techniques based on applying direct current (DC) non-invasively through the skin, transcranial cerebellar direct current stimulation (tDCS) and transcutaneous spinal DCS, can induce prolonged functional changes consistent with a direct influence on the human cerebellum and spinal cord. In this article we review the major experimental works on cerebellar tDCS and on spinal tDCS, and their preliminary clinical applications. Cerebellar tDCS modulates cerebellar motor cortical inhibition, gait adaptation, motor behaviour, and cognition (learning, language, memory, attention). Spinal tDCS influences the ascending and descending spinal pathways, and spinal reflex excitability. In the anaesthetised mouse, DC stimulation applied under the skin along the entire spinal cord may affect GABAergic and glutamatergic systems. Preliminary clinical studies in patients with cerebellar disorders, and in animals and patients with spinal cord injuries, have reported beneficial effects. Overall the available data show that cerebellar tDCS and spinal tDCS are two novel approaches for inducing prolonged functional changes and neuroplasticity in the human cerebellum and spinal cord, and both are new tools for experimental and clinical neuroscientists. PMID:24907311

Hypothesis for cognitive effects of transcranial direct current stimulation: Externally- and internally-directed cognition.

PubMed

Greenwood, Pamela M; Blumberg, Eric J; Scheldrup, Melissa R

2018-03-01

A comprehensive explanation is lacking for the broad array of cognitive effects modulated by transcranial direct current stimulation (tDCS). We advanced the testable hypothesis that tDCS to the default mode network (DMN) increases processing of goals and stored information at the expense of external events. We further hypothesized that tDCS to the dorsal attention network (DAN) increases processing of external events at the expense of goals and stored information. A literature search (PsychINFO) identified 42 empirical studies and 3 meta-analyses examining effects of prefrontal and/or parietal tDCS on tasks that selectively required external and/or internal processing. Most, though not all, of the studies that met our search criteria supported our hypothesis. Three meta-analyses supported our hypothesis. The hypothesis we advanced provides a framework for the design and interpretation of results in light of the role of large-scale intrinsic networks that govern attention. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcranial magnetic stimulation and transcranial direct current stimulation: treatments for cognitive and neuropsychiatric symptoms in the neurodegenerative dementias?

PubMed Central

2014-01-01

Introduction Two methods of non-invasive brain stimulation, transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have demonstrable positive effects on cognition and can ameliorate neuropsychiatric symptoms such as depression. Less is known about the efficacy of these approaches in common neurodegenerative diseases. In this review, we evaluate the effects of TMS and tDCS upon cognitive and neuropsychiatric symptoms in the major dementias, including Alzheimer’s disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB), Parkinson’s disease with dementia (PDD), and frontotemporal dementia (FTD), as well as the potential pre-dementia states of Mild Cognitive Impairment (MCI) and Parkinson’s disease (PD). Methods PubMed (until 7 February 2014) and PsycINFO (from 1967 to January Week 3 2014) databases were searched in a semi-systematic manner in order to identify relevant treatment studies. A total of 762 studies were identified and 32 studies (18 in the dementias and 14 in PD populations) were included. Results No studies were identified in patients with PDD, FTD or VaD. Of the dementias, 13 studies were conducted in patients with AD, one in DLB, and four in MCI. A total of 16 of the 18 studies showed improvements in at least one cognitive or neuropsychiatric outcome measure. Cognitive or neuropsychiatric improvements were observed in 12 of the 14 studies conducted in patients with PD. Conclusions Both TMS and tDCS may have potential as interventions for the treatment of symptoms associated with dementia and PD. These results are promising; however, available data were limited, particularly within VaD, PDD and FTD, and major challenges exist in order to maximise the efficacy and clinical utility of both techniques. In particular, stimulation parameters vary considerably between studies and are likely to subsequently impact upon treatment efficacy. PMID:25478032

Modulating Motor Learning through Transcranial Direct-Current Stimulation: An Integrative View

PubMed Central

Ammann, Claudia; Spampinato, Danny; Márquez-Ruiz, Javier

2016-01-01

Motor learning consists of the ability to improve motor actions through practice playing a major role in the acquisition of skills required for high-performance sports or motor function recovery after brain lesions. During the last decades, it has been reported that transcranial direct-current stimulation (tDCS), consisting in applying weak direct current through the scalp, is able of inducing polarity-specific changes in the excitability of cortical neurons. This low-cost, painless and well-tolerated portable technique has found a wide-spread use in the motor learning domain where it has been successfully applied to enhance motor learning in healthy individuals and for motor recovery after brain lesion as well as in pathological states associated to motor deficits. The main objective of this mini-review is to offer an integrative view about the potential use of tDCS for human motor learning modulation. Furthermore, we introduce the basic mechanisms underlying immediate and long-term effects associated to tDCS along with important considerations about its limitations and progression in recent years. PMID:28066300

Surgical treatment of insular tumours with tractography, functional magnetic resonance imaging, transcranial electrical stimulation and direct subcortical stimulation support.

PubMed

Majchrzak, Krzysztof; Bobek-Billewicz, Barbara; Tymowski, Michał; Adamczyk, Piotr; Majchrzak, Hneryk; Ladziński, Piotr

2011-01-01

Surgical treatment of insular tumours carries significant risks of limb paresis or speech disturbances due to their localization. The development of intraoperative neuromonitoring techniques that involve evoked motor potentials induced via both direct and transcranial cortical electrical stimulation as well as direct subcortical white matter stimulation, intraoperative application of preoperative tractography and functional magnetic resonance imaging (fMRI) in conjunction with neuronavigation resulted in significant reduction of postoperative disabilities that enabled widening of indications for surgical treatment. The aim of this study was to present the authors' own experience with surgical treatment of insular gliomas. Our cohort comprises 30 patients with insular gliomas treated at the Department of Neurosurgery in Sosnowiec. Clinical symptoms included sensorimotor partial seizures in 86.6%; generalized seizures in 23.3%; persistent headaches in 16.6% and hemiparesis in 6.6%. All the patients were operated on with intraoperative neuromonitoring that included transcranial cortical stimulation, direct subcortical white matter stimulation as well as tractography and fMRI concurrently with neuronavigation. The analysis in-cluded postoperative neurological evaluation along with the assessment of the radicalism of resection evaluated based on postoperative MRI. Postoperatively, four patients had permanent hemiparesis (13.3%); importantly, two out of those patients had preoperative deficits (6.6%). Persistent speech disturbances were present in four patients (13.3%). Partial sensorimotor seizures were noted in two patients (6.6%). Seizures in the other patients receded. Intraoperative transcranial electrical stimulation as well as direct subcortical white matter stimulation along with tractography (DTI) and fMRI facilitated gross total resection of insular gliomas in 53.5%, subtotal in 13.3% and partial resection in 33.1%. Implementation of TES, direct subcortical

Transcranial direct current stimulation: a noninvasive tool to facilitate stroke recovery

PubMed Central

Schlaug, Gottfried; Renga, Vijay

2011-01-01

Electrical brain stimulation, a technique developed many decades ago and then largely forgotten, has re-emerged recently as a promising tool for experimental neuroscientists, clinical neurologists and psychiatrists in their quest to causally probe cortical representations of sensorimotor and cognitive functions and to facilitate the treatment of various neuropsychiatric disorders. In this regard, a better understanding of adaptive and maladaptive plasticity in natural stroke recovery over the last decade and the idea that brain polarization may modulate neuroplasticity has led to the use of transcranial direct current stimulation (tDCS) as a potential enhancer of natural stroke recovery. We will review tDCS’s successful utilization in pilot and proof-of-principle stroke recovery studies, the different modes of tDCS currently in use, and the potential mechanisms underlying the neural effects of tDCS. PMID:19025351

Transcranial direct current stimulation combined with upper limb functional training in children with spastic, hemiparetic cerebral palsy: study protocol for a randomized controlled trial.

PubMed

Moura, Renata Calhes Franco; Santos, Cibele Almeida; Grecco, Luanda André Collange; Lazzari, Roberta Delasta; Dumont, Arislander Jonathan Lopes; Duarte, Natalia Carvalho de Almeida; Braun, Luiz Alfredo; Lopes, Jamile Benite Palma; Santos, Ligia Abram Dos; Rodrigues, Eliane Lopes Souza; Albertini, Giorgio; Cimolin, Veronica; Galli, Manuela; Oliveira, Claudia Santos

2016-08-17

The aim of the proposed study is to perform a comparative analysis of functional training effects for the paretic upper limb with and without transcranial direct current stimulation over the primary motor cortex in children with spastic hemiparetic cerebral palsy. The sample will comprise 34 individuals with spastic hemiparetic cerebral palsy, 6 to 16 years old, classified at level I, II, or III of the Manual Ability Classification System. Participants will be randomly allocated to two groups: (1) functional training of the paretic upper limb combined with anodic transcranial stimulation; (2) functional training of the paretic upper limb combined with sham transcranial stimulation. Evaluation will involve three-dimensional movement analysis and electromyography using the SMART-D 140® system (BTS Engineering) and the FREEEMG® system (BTS Engineering), the Quality of Upper Extremity Skills Test, to assess functional mobility, the Portable Device and Ashworth Scale, to measure movement resistance and spasticity, and the Pediatric Evaluation of Disability Inventory, to evaluate performance. Functional reach training of the paretic upper limb will include a range of manual activities using educational toys associated with an induced constraint of the non-paretic limb during the training. Training will be performed in five weekly 20-minute sessions for two weeks. Transcranial stimulation over the primary motor cortex will be performed during the training sessions at an intensity of 1 mA. Findings will be analyzed statistically considering a 5 % significance level (P ≤ 0.05). This paper presents a detailed description of a prospective, randomized, controlled, double-blind, clinical trial designed to demonstrate the effects of combining transcranial direct current stimulation over the primary motor cortex and functional training of the paretic limb in children with cerebral palsy classified at level I, II, or III of the Manual Ability Classification System. The

High-resolution Modeling Assisted Design of Customized and Individualized Transcranial Direct Current Stimulation Protocols

PubMed Central

Bikson, Marom; Rahman, Asif; Datta, Abhishek; Fregni, Felipe; Merabet, Lotfi

2012-01-01

Objectives Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity currents facilitating or inhibiting spontaneous neuronal activity. tDCS is attractive since dose is readily adjustable by simply changing electrode number, position, size, shape, and current. In the recent past, computational models have been developed with increased precision with the goal to help customize tDCS dose. The aim of this review is to discuss the incorporation of high-resolution patient-specific computer modeling to guide and optimize tDCS. Methods In this review, we discuss the following topics: (i) The clinical motivation and rationale for models of transcranial stimulation is considered pivotal in order to leverage the flexibility of neuromodulation; (ii) The protocols and the workflow for developing high-resolution models; (iii) The technical challenges and limitations of interpreting modeling predictions, and (iv) Real cases merging modeling and clinical data illustrating the impact of computational models on the rational design of rehabilitative electrotherapy. Conclusions Though modeling for non-invasive brain stimulation is still in its development phase, it is predicted that with increased validation, dissemination, simplification and democratization of modeling tools, computational forward models of neuromodulation will become useful tools to guide the optimization of clinical electrotherapy. PMID:22780230

Effect of a single session of transcranial direct-current stimulation combined with virtual reality training on the balance of children with cerebral palsy: a randomized, controlled, double-blind trial

PubMed Central

Lazzari, Roberta Delasta; Politti, Fabiano; Santos, Cibele Alimedia; Dumont, Arislander Jonathan Lopes; Rezende, Fernanda Lobo; Grecco, Luanda André Collange; Braun Ferreira, Luiz Alfredo; Oliveira, Claudia Santos

2015-01-01

[Purpose] The aim of the present study was to investigate the effects of a single session of transcranial direct current stimulation combined with virtual reality training on the balance of children with cerebral palsy. [Subjetcs and Methods] Children with cerebral palsy between four and 12 years of age were randomly allocated to two groups: an experimental group which performed a single session of mobility training with virtual reality combined with active transcranial direct current stimulation; and a control group which performed a single session of mobility training with virtual reality combined with placebo transcranial direct current stimulation. The children were evaluated before and after the training protocols. Static balance (sway area, displacement, velocity and frequency of oscillations of the center of pressure on the anteroposterior and mediolateral axes) was evaluated using a force plate under four conditions (30-second measurements for each condition): feet on the force plate with the eyes open, and with the eyes closed; feet on a foam mat with the eyes open, and with the eyes closed. [Results] An increase in sway velocity was the only significant difference found. [Conclusion] A single session of anodal transcranial direct current stimulation combined with mobility training elicited to lead to an increase in the body sway velocity of children with cerebral palsy. PMID:25931726

Effect of transcranial direct current stimulation on vestibular-ocular and vestibulo-perceptual thresholds.

PubMed

Kyriakareli, Artemis; Cousins, Sian; Pettorossi, Vito E; Bronstein, Adolfo M

2013-10-02

Transcranial direct current stimulation (tDCS) was used in 17 normal individuals to modulate vestibulo-ocular reflex (VOR) and self-motion perception rotational thresholds. The electrodes were applied over the temporoparietal junction bilaterally. Both vestibular nystagmic and perceptual thresholds were increased during as well as after tDCS stimulation. Body rotation was labeled as ipsilateral or contralateral to the anode side, but no difference was observed depending on the direction of rotation or hemisphere polarity. Threshold increase during tDCS was greater for VOR than for motion perception. 'Sham' stimulation had no effect on thresholds. We conclude that tDCS produces an immediate and sustained depression of cortical regions controlling VOR and movement perception. Temporoparietal areas appear to be involved in vestibular threshold modulation but the differential effects observed between VOR and perception suggest a partial dissociation between cortical processing of reflexive and perceptual responses.

Acute and chronic effects of noradrenergic enhancement on transcranial direct current stimulation-induced neuroplasticity in humans.

PubMed

Kuo, Hsiao-I; Paulus, Walter; Batsikadze, Giorgi; Jamil, Asif; Kuo, Min-Fang; Nitsche, Michael A

2017-02-15

Chronic administration of the selective noradrenaline reuptake inhibitor (NRI) reboxetine (RBX) increased and prolonged the long-term potentiation-like plasticity induced by anodal transcranial direct current stimulation (tDCS) for over 24 h. Chronic administration of RBX converted cathodal tDCS-induced long-term depression-like plasticity into facilitation for 120 min. Chronic noradrenergic activity enhancement on plasticity of the human brain might partially explain the delayed therapeutic impact of selective NRIs in depression and other neuropsychiatric diseases. Noradrenaline affects cognition and motor learning processes via its impact on long-term potentiation (LTP) and depression (LTD). We aimed to explore the impact of single dose and chronic administration of the selective noradrenaline reuptake inhibitor (NRI) reboxetine (RBX) on plasticity induced by transcranial direct current stimulation (tDCS) in healthy humans via a double-blinded, placebo-controlled, randomized crossover study. Sixteen healthy volunteers received placebo or single dose RBX (8 mg) before anodal or cathodal tDCS of the primary motor cortex. Afterwards, the same subjects took RBX (8 mg day -1 ) consecutively for 21 days. During this period, two additional interventions were performed (RBX with anodal or cathodal tDCS), to explore the impact of chronic RBX treatment on plasticity. Plasticity was monitored by motor-evoked potential amplitudes elicited by transcranial magnetic stimulation. Chronic administration of RBX increased and prolonged the LTP-like plasticity induced by anodal tDCS for over 24 h. Chronic RBX significantly converted cathodal tDCS-induced LTD-like plasticity into facilitation, as compared to the single dose condition, for 120 min after stimulation. The results show a prominent impact of chronic noradrenergic enhancement on plasticity of the human brain that might partially explain the delayed therapeutic impact of selective NRIs in depression and other

The effects of combined repetitive transcranial magnetic stimulation and transcranial direct current stimulation on motor function in patients with stroke.

PubMed

Kwon, Tae Gun; Park, Eunhee; Kang, Chung; Chang, Won Hyuk; Kim, Yun-Hee

2016-11-22

Both transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), when provided to stroke patients in combination with motor training, enhance therapeutic efficacy and motor function. However, the majority of previous studies have only examined a single treatment modality. The authors investigated the modulating influence of combination dual-mode brain stimulation upon bihemispheric stimulation with motor training in stroke patients. Twenty stroke patients with hemiparesis underwent five randomly arranged sessions of diverse combinations of rTMS and tDCS. We applied cathodal or anodal tDCS over the contralesional primary motor cortex (cM1) and 10 Hz rTMS over the ipsilesional primary motor cortex (iM1) in a simultaneous or preconditioning method including sham stimulation. Immediately after dual-mode stimulation, sequential hand motor training was performed for 5 minutes. The total pulses of rTMS and the duration of tDCS and motor training were the same for all sessions. Cortical excitability and sequential motor performance were evaluated before and after each session. Motor function and corticomotor excitability following simultaneous stimulation via cathodal tDCS over the cM1 combined with 10 Hz rTMS over the iM1 were significantly increased after the intervention, with significantly greater motor improvement than seen with other treatment conditions (P < 0.05). For the combination of bihemispheric rTMS and tDCS, simultaneous stimulation of cathodal tDCS and 10 Hz rTMS results in better motor performance in stroke patients than other combination methods. This result seemed to be related to effective modulation of interhemispheric imbalance of cortical excitability by dual-mode stimulation.

Enhancing Working Memory Training with Transcranial Direct Current Stimulation.

PubMed

Au, Jacky; Katz, Benjamin; Buschkuehl, Martin; Bunarjo, Kimberly; Senger, Thea; Zabel, Chelsea; Jaeggi, Susanne M; Jonides, John

2016-09-01

Working memory (WM) is a fundamental cognitive ability that supports complex thought but is limited in capacity. Thus, WM training interventions have become very popular as a means of potentially improving WM-related skills. Another promising intervention that has gained increasing traction in recent years is transcranial direct current stimulation (tDCS), a noninvasive form of brain stimulation that can modulate cortical excitability and temporarily increase brain plasticity. As such, it has the potential to boost learning and enhance performance on cognitive tasks. This study assessed the efficacy of tDCS to supplement WM training. Sixty-two participants were randomized to receive either right prefrontal, left prefrontal, or sham stimulation with concurrent visuospatial WM training over the course of seven training sessions. Results showed that tDCS enhanced training performance, which was strikingly preserved several months after training completion. Furthermore, we observed stronger effects when tDCS was spaced over a weekend break relative to consecutive daily training, and we also demonstrated selective transfer in the right prefrontal group to nontrained tasks of visual and spatial WM. These findings shed light on how tDCS may be leveraged as a tool to enhance performance on WM-intensive learning tasks.

Rigor and reproducibility in research with transcranial electrical stimulation: An NIMH-sponsored workshop

PubMed Central

Bikson, Marom; Brunoni, Andre R.; Charvet, Leigh E.; Clark, Vincent P.; Cohen, Leonardo G.; Deng, Zhi-De; Dmochowski, Jacek; Edwards, Dylan J.; Frohlich, Flavio; Kappenman, Emily S.; Lim, Kelvin O.; Loo, Colleen; Mantovani, Antonio; McMullen, David P.; Parra, Lucas C.; Pearson, Michele; Richardson, Jessica D.; Rumsey, Judith M.; Sehatpour, Pejman; Sommers, David; Unal, Gozde; Wassermann, Eric M.; Woods, Adam J.; Lisanby, Sarah H.

2018-01-01

Background Neuropsychiatric disorders are a leading source of disability and require novel treatments that target mechanisms of disease. As such disorders are thought to result from aberrant neuronal circuit activity, neuromodulation approaches are of increasing interest given their potential for manipulating circuits directly. Low intensity transcranial electrical stimulation (tES) with direct currents (transcranial direct current stimulation, tDCS) or alternating currents (transcranial alternating current stimulation, tACS) represent novel, safe, well-tolerated, and relatively inexpensive putative treatment modalities. Objective This report seeks to promote the science, technology and effective clinical applications of these modalities, identify research challenges, and suggest approaches for addressing these needs in order to achieve rigorous, reproducible findings that can advance clinical treatment. Methods The National Institute of Mental Health (NIMH) convened a workshop in September 2016 that brought together experts in basic and human neuroscience, electrical stimulation biophysics and devices, and clinical trial methods to examine the physiological mechanisms underlying tDCS/tACS, technologies and technical strategies for optimizing stimulation protocols, and the state of the science with respect to therapeutic applications and trial designs. Results Advances in understanding mechanisms, methodological and technological improvements (e.g., electronics, computational models to facilitate proper dosing), and improved clinical trial designs are poised to advance rigorous, reproducible therapeutic applications of these techniques. A number of challenges were identified and meeting participants made recommendations made to address them. Conclusions These recommendations align with requirements in NIMH funding opportunity announcements to, among other needs, define dosimetry, demonstrate dose/response relationships, implement rigorous blinded trial designs

Transcranial Alternating Current Stimulation Attenuates Neuronal Adaptation.

PubMed

Kar, Kohitij; Duijnhouwer, Jacob; Krekelberg, Bart

2017-03-01

We previously showed that brief application of 2 mA (peak-to-peak) transcranial currents alternating at 10 Hz significantly reduces motion adaptation in humans. This is but one of many behavioral studies showing that weak currents applied to the scalp modulate neural processing. Transcranial stimulation has been shown to improve perception, learning, and a range of clinical symptoms. Few studies, however, have measured the neural consequences of transcranial current stimulation. We capitalized on the strong link between motion perception and neural activity in the middle temporal (MT) area of the macaque monkey to study the neural mechanisms that underlie the behavioral consequences of transcranial alternating current stimulation. First, we observed that 2 mA currents generated substantial intracranial fields, which were much stronger in the stimulated hemisphere (0.12 V/m) than on the opposite side of the brain (0.03 V/m). Second, we found that brief application of transcranial alternating current stimulation at 10 Hz reduced spike-frequency adaptation of MT neurons and led to a broadband increase in the power spectrum of local field potentials. Together, these findings provide a direct demonstration that weak electric fields applied to the scalp significantly affect neural processing in the primate brain and that this includes a hitherto unknown mechanism that attenuates sensory adaptation. SIGNIFICANCE STATEMENT Transcranial stimulation has been claimed to improve perception, learning, and a range of clinical symptoms. Little is known, however, how transcranial current stimulation generates such effects, and the search for better stimulation protocols proceeds largely by trial and error. We investigated, for the first time, the neural consequences of stimulation in the monkey brain. We found that even brief application of alternating current stimulation reduced the effects of adaptation on single-neuron firing rates and local field potentials; this mechanistic

Enhanced motor learning with bilateral transcranial direct current stimulation: Impact of polarity or current flow direction?

PubMed

Naros, Georgios; Geyer, Marc; Koch, Susanne; Mayr, Lena; Ellinger, Tabea; Grimm, Florian; Gharabaghi, Alireza

2016-04-01

Bilateral transcranial direct current stimulation (TDCS) is superior to unilateral TDCS when targeting motor learning. This effect could be related to either the current flow direction or additive polarity-specific effects on each hemisphere. This sham-controlled randomized study included fifty right-handed healthy subjects in a parallel-group design who performed an exoskeleton-based motor task of the proximal left arm on three consecutive days. Prior to training, we applied either sham, right anodal (a-TDCS), left cathodal (c-TDCS), concurrent a-TDCS and c-TDCS with two independent current sources and return electrodes (double source (ds)-TDCS) or classical bilateral stimulation (bi-TDCS). Motor performance improved over time for both unilateral (a-TDCS, c-TDCS) and bilateral (bi-TDCS, ds-TDCS) TDCS montages. However, only the two bilateral paradigms led to an improvement of the final motor performance at the end of the training period as compared to the sham condition. There was no difference between the two bilateral stimulation conditions (bi-TDCS, ds-TDCS). Bilateral TDCS is more effective than unilateral stimulation due to its polarity-specific effects on each hemisphere rather than due to its current flow direction. This study is the first systematic evaluation of stimulation polarity and current flow direction of bi-hemispheric motor cortex TDCS on motor learning of proximal upper limb muscles. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Patient-conducted anodal transcranial direct current stimulation of the motor cortex alleviates pain in trigeminal neuralgia

PubMed Central

2014-01-01

Background Transcranial direct current stimulation (tDCS) of the primary motor cortex has been shown to modulate pain and trigeminal nociceptive processing. Methods Ten patients with classical trigeminal neuralgia (TN) were stimulated daily for 20 minutes over two weeks using anodal (1 mA) or sham tDCS over the primary motor cortex (M1) in a randomized double-blind cross-over design. Primary outcome variable was pain intensity on a verbal rating scale (VRS 0–10). VRS and attack frequency were assessed for one month before, during and after tDCS. The impact on trigeminal pain processing was assessed with pain-related evoked potentials (PREP) and the nociceptive blink reflex (nBR) following electrical stimulation on both sides of the forehead before and after tDCS. Results Anodal tDCS reduced pain intensity significantly after two weeks of treatment. The attack frequency reduction was not significant. PREP showed an increased N2 latency and decreased peak-to-peak amplitude after anodal tDCS. No severe adverse events were reported. Conclusion Anodal tDCS over two weeks ameliorates intensity of pain in TN. It may become a valuable treatment option for patients unresponsive to conventional treatment. PMID:25424567

Chronic Enhancement of Serotonin Facilitates Excitatory Transcranial Direct Current Stimulation-Induced Neuroplasticity.

PubMed

Kuo, Hsiao-I; Paulus, Walter; Batsikadze, Giorgi; Jamil, Asif; Kuo, Min-Fang; Nitsche, Michael A

2016-04-01

Serotonin affects memory formation via modulating long-term potentiation (LTP) and depression (LTD). Accordingly, acute selective serotonin reuptake inhibitor (SSRI) administration enhanced LTP-like plasticity induced by transcranial direct current stimulation (tDCS) in humans. However, it usually takes some time for SSRI to reduce clinical symptoms such as anxiety, negative mood, and related symptoms of depression and anxiety disorders. This might be related to an at least partially different effect of chronic serotonergic enhancement on plasticity, as compared with single-dose medication. Here we explored the impact of chronic application of the SSRI citalopram (CIT) on plasticity induced by tDCS in healthy humans in a partially double-blinded, placebo (PLC)-controlled, randomized crossover study. Furthermore, we explored the dependency of plasticity induction from the glutamatergic system via N-methyl-D-aspartate receptor antagonism. Twelve healthy subjects received PLC medication, combined with anodal or cathodal tDCS of the primary motor cortex. Afterwards, the same subjects took CIT (20 mg/day) consecutively for 35 days. During this period, four additional interventions were performed (CIT and PLC medication with anodal/cathodal tDCS, CIT and dextromethorphan (150 mg) with anodal/cathodal tDCS). Plasticity was monitored by motor-evoked potential amplitudes elicited by transcranial magnetic stimulation. Chronic application of CIT increased and prolonged the LTP-like plasticity induced by anodal tDCS for over 24 h, and converted cathodal tDCS-induced LTD-like plasticity into facilitation. These effects were abolished by dextromethorphan. Chronic serotonergic enhancement results in a strengthening of LTP-like glutamatergic plasticity, which might partially explain the therapeutic impact of SSRIs in depression and other neuropsychiatric diseases.

Modulating Human Auditory Processing by Transcranial Electrical Stimulation

PubMed Central

Heimrath, Kai; Fiene, Marina; Rufener, Katharina S.; Zaehle, Tino

2016-01-01

Transcranial electrical stimulation (tES) has become a valuable research tool for the investigation of neurophysiological processes underlying human action and cognition. In recent years, striking evidence for the neuromodulatory effects of transcranial direct current stimulation, transcranial alternating current stimulation, and transcranial random noise stimulation has emerged. While the wealth of knowledge has been gained about tES in the motor domain and, to a lesser extent, about its ability to modulate human cognition, surprisingly little is known about its impact on perceptual processing, particularly in the auditory domain. Moreover, while only a few studies systematically investigated the impact of auditory tES, it has already been applied in a large number of clinical trials, leading to a remarkable imbalance between basic and clinical research on auditory tES. Here, we review the state of the art of tES application in the auditory domain focussing on the impact of neuromodulation on acoustic perception and its potential for clinical application in the treatment of auditory related disorders. PMID:27013969

Prefrontal transcranial direct current stimulation alters activation and connectivity in cortical and subcortical reward systems: a tDCS-fMRI study.

PubMed

Weber, Matthew J; Messing, Samuel B; Rao, Hengyi; Detre, John A; Thompson-Schill, Sharon L

2014-08-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique used both experimentally and therapeutically to modulate regional brain function. However, few studies have directly measured the aftereffects of tDCS on brain activity or examined changes in task-related brain activity consequent to prefrontal tDCS. To investigate the neural effects of tDCS, we collected fMRI data from 22 human subjects, both at rest and while performing the Balloon Analog Risk Task (BART), before and after true or sham transcranial direct current stimulation. TDCS decreased resting blood perfusion in orbitofrontal cortex and the right caudate and increased task-related activity in the right dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) in response to losses but not wins or increasing risk. Network analysis showed that whole-brain connectivity of the right ACC correlated positively with the number of pumps subjects were willing to make on the BART, and that tDCS reduced connectivity between the right ACC and the rest of the brain. Whole-brain connectivity of the right DLPFC also correlated negatively with pumps on the BART, as prior literature would suggest. Our results suggest that tDCS can alter activation and connectivity in regions distal to the electrodes. Copyright © 2014 Wiley Periodicals, Inc.

Surface EEG-Transcranial Direct Current Stimulation (tDCS) Closed-Loop System.

PubMed

Leite, Jorge; Morales-Quezada, Leon; Carvalho, Sandra; Thibaut, Aurore; Doruk, Deniz; Chen, Chiun-Fan; Schachter, Steven C; Rotenberg, Alexander; Fregni, Felipe

2017-09-01

Conventional transcranial direct current stimulation (tDCS) protocols rely on applying electrical current at a fixed intensity and duration without using surrogate markers to direct the interventions. This has led to some mixed results; especially because tDCS induced effects may vary depending on the ongoing level of brain activity. Therefore, the objective of this preliminary study was to assess the feasibility of an EEG-triggered tDCS system based on EEG online analysis of its frequency bands. Six healthy volunteers were randomized to participate in a double-blind sham-controlled crossover design to receive a single session of 10[Formula: see text]min 2[Formula: see text]mA cathodal and sham tDCS. tDCS trigger controller was based upon an algorithm designed to detect an increase in the relative beta power of more than 200%, accompanied by a decrease of 50% or more in the relative alpha power, based on baseline EEG recordings. EEG-tDCS closed-loop-system was able to detect the predefined EEG magnitude deviation and successfully triggered the stimulation in all participants. This preliminary study represents a proof-of-concept for the development of an EEG-tDCS closed-loop system in humans. We discuss and review here different methods of closed loop system that can be considered and potential clinical applications of such system.

Transcranial direct current stimulation in the male mouse to promote recovery after stroke.

PubMed

Pikhovych, Anton; Walter, Helene L; Mahabir, Esther; Fink, Gereon Rudolf; Graf, Rudolf; Schroeter, Michael; Rueger, Maria Adele

2016-06-01

Transcranial direct current stimulation (tDCS) constitutes a promising approach for promoting recovery of function after stroke, although the underlying neurobiological mechanisms are unclear. To conduct translational research in animal models, stimulation parameters should not lead to neuronal lesions. Liebetanz et al. recommend charge densities for cathodal stimulation in rats, but parameters for mice are not established. We established tDCS in the wild-type mouse, enabling studies with genetically-engineered mice (GEM). tDCS equipment was adapted to fit the mouse skull. Using different polarities and charge densities, tDCS was safe to apply in the mouse where the charge density was below 198 kC/m(2) for single or repeated stimulations. These findings are crucial for future investigations of the neurobiological mechanisms underlying tDCS using GEM. © The Author(s) 2015.

Enhancing the mirror illusion with transcranial direct current stimulation.

PubMed

Jax, Steven A; Rosa-Leyra, Diana L; Coslett, H Branch

2015-05-01

Visual feedback has a strong impact on upper-extremity movement production. One compelling example of this phenomena is the mirror illusion (MI), which has been used as a treatment for post-stroke movement deficits (mirror therapy). Previous research indicates that the MI increases primary motor cortex excitability, and this change in excitability is strongly correlated with the mirror's effects on behavioral performance of neurologically-intact controls. Based on evidence that primary motor cortex excitability can also be increased using transcranial direct current stimulation (tDCS), we tested whether bilateral tDCS to the primary motor cortices (anode right-cathode left and anode left-cathode right) would modify the MI. We measured the MI using a previously-developed task in which participants make reaching movements with the unseen arm behind a mirror while viewing the reflection of the other arm. When an offset in the positions of the two limbs relative to the mirror is introduced, reaching errors of the unseen arm are biased by the reflected arm's position. We found that active tDCS in the anode right-cathode left montage increased the magnitude of the MI relative to sham tDCS and anode left-cathode right tDCS. We take these data as a promising indication that tDCS could improve the effect of mirror therapy in patients with hemiparesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modulating risky decision-making in Parkinson's disease by transcranial direct current stimulation.

PubMed

Benussi, A; Alberici, A; Cantoni, V; Manenti, R; Brambilla, M; Dell'Era, V; Gazzina, S; Manes, M; Cristillo, V; Padovani, A; Cotelli, M; Borroni, B

2017-05-01

Performance on gambling tasks in Parkinson's disease (PD) is of particular interest, as pathological gambling is often associated with dopamine replacement therapy in these patients. We aimed to evaluate the effects of transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (DLPFC) in modulating gambling behaviour in PD. We assessed the effects of cathodal tDCS over the right DLPFC during the Iowa Gambling Task in 20 patients with PD, compared with sham stimulation. We then conducted a second experimental design, assessing the effects of anodal tDCS over the right DLPFC. We observed that cathodal tDCS over the right DLPFC increased Iowa Gambling Task scores compared with sham stimulation. In the second experimental design, we did not find significant differences between anodal and sham tDCS. Cathodal tDCS over the right DLPFC possibly reduces the pathological overdrive in frontostriatal networks in patients with PD on dopaminergic medication, thus modulating impulsive and risky decision-making. © 2017 EAN.

Delayed enhancement of multitasking performance: Effects of anodal transcranial direct current stimulation on the prefrontal cortex

PubMed Central

Hsu, Wan-Yu; Zanto, Theodore P.; Anguera, Joaquin A.; Lin, Yung-Yang; Gazzaley, Adam

2015-01-01

Background The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance. However, this claim is underexplored in terms of direct causal evidence. Objective The current study aimed to delineate the causal involvement of the DLPFC during multitasking by modulating neural activity with transcranial direct current stimulation (tDCS) prior to engagement in a demanding multitasking paradigm. Methods The study is a single-blind, crossover, sham-controlled experiment. Anodal tDCS or sham tDCS was applied over left DLPFC in forty-one healthy young adults (aged 18–35 years) immediately before they engaged in a 3-D video game designed to assess multitasking performance. Participants were separated into three subgroups: real-sham (i.e., real tDCS in the first session, followed by sham tDCS in the second session one hour later), sham-real (sham tDCS first session, real tDCS second session), and sham-sham (sham tDCS in both sessions). Results The real-sham group showed enhanced multitasking performance and decreased multitasking cost during the second session, compared to first session, suggesting delayed cognitive benefits of tDCS. Interestingly, performance benefits were observed only for multitasking and not on a single-task version of the game. No significant changes were found between the first and second sessions for either the sham-real or the sham-sham groups. Conclusions These results suggest a causal role of left prefrontal cortex in facilitating the simultaneous performance of more than one task, or multitasking. Moreover, these findings reveal that anodal tDCS may have delayed benefits that reflect an enhanced rate of learning. PMID:26073148

Transcranial direct current stimulation enhances verbal working memory training performance over time and near transfer outcomes.

PubMed

Richmond, Lauren L; Wolk, David; Chein, Jason; Olson, Ingrid R

2014-11-01

Studies attempting to increase working memory (WM) capacity show promise in enhancing related cognitive functions but have also raised criticism in the broader scientific community given the inconsistent findings produced by these studies. Transcranial direct current stimulation (tDCS) has been shown to enhance WM performance in a single session [Fregni, F., Boggio, P., Nitsche, M., Bermpohl, F., Anatal, A., Feredoes, E., et al. Anodal transcranial direct current stimulation of prefrontal cortex enhances working memory. Experimental Brain Research, 166, 23-30, 2005]; however, the extent to which tDCS might enhance learning on a WM training regime and the extent to which learning gains might transfer outside the training task remains largely unknown. To this end, participants engaged in an adaptive WM training task [previously utilized in Richmond, L., Morrison, A., Chein, J., & Olson, I. Working memory training and transfer in older adults. Psychology & Aging, 26, 813-822, 2011; Chein, J., & Morrison, A. Expanding the mind's workspace: Training and transfer effects with a complex working memory span task. Psychonomic Bulletin & Review, 17, 193-199, 2010] for 10 sessions over 2 weeks, concurrent with either active or sham stimulation of dorsolateral pFC. Before and after training, a battery of tests tapping domains known to relate to WM abilities was administered. Results show that tDCS enhanced learning on the verbal portion of the training task by 3.65 items. Furthermore, tDCS was shown to enhance near transfer to other untrained WM tasks in comparison with a no-contact control group. These results lend support to the idea that tDCS might bolster training and transfer gains in populations with compromised WM abilities.

Methods for Specific Electrode Resistance Measurement during Transcranial Direct Current Stimulation

PubMed Central

Khadka, Niranjan; Rahman, Asif; Sarantos, Chris; Truong, Dennis Q.; Bikson, Marom

2014-01-01

Background Transcranial Direct Current Stimulation (tDCS) is investigated to treat a wide range of neuropsychiatric disorders, for rehabilitation, and for enhancing cognitive performance. The monitoring of electrode resistance before and during tDCS is considered important for tolerability and safety, where an unusually high resistance is indicative of undesired electrode or poor skin contact conditions. Conventional resistance measurement methods do not isolate individual electrode resistance but rather measures overall voltage. Moreover, for HD-tDCS devices, cross talk across electrodes makes concurrent resistance monitoring unreliable. Objective We propose a novel method for monitoring of the individual electrode resistance during tDCS, using a super-position of direct current with a test-signal (low-intensity and low-frequency sinusoids with electrode– specific frequencies) and a single sentinel electrode (not used for DC). Methods To validate this methodology, we developed lumped-parameter models of two and multi-electrode tDCS. Approaches with and without a sentinel electrode were solved and underlying assumptions identified. Assumptions were tested and parameterized in healthy participants using forearm stimulation combining tDCS (2 mA) and sinusoidal test-signals (38 μA and 76 μA peak to peak at 1 Hz, 10 Hz, and 100 Hz) and an in vitro test (where varied electrode failure modes were created). DC and AC component voltages across the electrodes were compared and participants were asked to rate subjective pain. Results A sentinel electrode is required to isolate electrode resistance in a two-electrode tDCS system. For multi-electrode resistance tracking, cross talk was aggravated with electrode proximity and current/resistance mismatches, but could be corrected using proposed approaches. Average voltage and average pain scores were not significantly different across test current intensities and frequencies (two-way repeated measures ANOVA) indicating the

Transcranial electric stimulation for the investigation of speech perception and comprehension

PubMed Central

Zoefel, Benedikt; Davis, Matthew H.

2017-01-01

ABSTRACT Transcranial electric stimulation (tES), comprising transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), involves applying weak electrical current to the scalp, which can be used to modulate membrane potentials and thereby modify neural activity. Critically, behavioural or perceptual consequences of this modulation provide evidence for a causal role of neural activity in the stimulated brain region for the observed outcome. We present tES as a tool for the investigation of which neural responses are necessary for successful speech perception and comprehension. We summarise existing studies, along with challenges that need to be overcome, potential solutions, and future directions. We conclude that, although standardised stimulation parameters still need to be established, tES is a promising tool for revealing the neural basis of speech processing. Future research can use this method to explore the causal role of brain regions and neural processes for the perception and comprehension of speech. PMID:28670598

Safety of transcranial Direct Current Stimulation: Evidence Based Update 2016

PubMed Central

Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R.; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H.; Hampstead, Benjamin M.; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A.; Reis, Janine; Richardson, Jessica D.; Rotenberg, Alexander; Turkeltaub, Peter E.; Woods, Adam J.

2016-01-01

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3–13 A/m2) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 mA, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1,000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. PMID:27372845

Enhancing transcranial direct current stimulation via motor imagery and kinesthetic illusion: crossing internal and external tools.

PubMed

Bodranghien, Florian; Manto, Mario; Lebon, Florent

2016-06-01

Transcranial direct current stimulation is a safe technique which is now part of the therapeutic armamentarium for the neuromodulation of motor functions and cognitive operations. It is currently considered that tDCS is an intervention that might promote functional recovery after a lesion in the central nervous system, thus reducing long-term disability and associated socio-economic burden. A recent study shows that kinesthetic illusion and motor imagery prolong the effects of tDCS on corticospinal excitability, overcoming one of the limitations of this intervention. Because changes in excitability anticipate changes in structural plasticity in the CNS, this interesting multi-modal approach might very soon find applications in neurorehabilitation.

Non-invasive brain stimulation and computational models in post-stroke aphasic patients: single session of transcranial magnetic stimulation and transcranial direct current stimulation. A randomized clinical trial.

PubMed

Santos, Michele Devido Dos; Cavenaghi, Vitor Breseghello; Mac-Kay, Ana Paula Machado Goyano; Serafim, Vitor; Venturi, Alexandre; Truong, Dennis Quangvinh; Huang, Yu; Boggio, Paulo Sérgio; Fregni, Felipe; Simis, Marcel; Bikson, Marom; Gagliardi, Rubens José

2017-01-01

Patients undergoing the same neuromodulation protocol may present different responses. Computational models may help in understanding such differences. The aims of this study were, firstly, to compare the performance of aphasic patients in naming tasks before and after one session of transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS) and sham, and analyze the results between these neuromodulation techniques; and secondly, through computational model on the cortex and surrounding tissues, to assess current flow distribution and responses among patients who received tDCS and presented different levels of results from naming tasks. Prospective, descriptive, qualitative and quantitative, double blind, randomized and placebo-controlled study conducted at Faculdade de Ciências Médicas da Santa Casa de São Paulo. Patients with aphasia received one session of tDCS, TMS or sham stimulation. The time taken to name pictures and the response time were evaluated before and after neuromodulation. Selected patients from the first intervention underwent a computational model stimulation procedure that simulated tDCS. The results did not indicate any statistically significant differences from before to after the stimulation.The computational models showed different current flow distributions. The present study did not show any statistically significant difference between tDCS, TMS and sham stimulation regarding naming tasks. The patients'responses to the computational model showed different patterns of current distribution.

The Homeostatic Interaction Between Anodal Transcranial Direct Current Stimulation and Motor Learning in Humans is Related to GABAA Activity.

PubMed

Amadi, Ugwechi; Allman, Claire; Johansen-Berg, Heidi; Stagg, Charlotte J

2015-01-01

The relative timing of plasticity-induction protocols is known to be crucial. For example, anodal transcranial direct current stimulation (tDCS), which increases cortical excitability and typically enhances plasticity, can impair performance if it is applied before a motor learning task. Such timing-dependent effects have been ascribed to homeostatic plasticity, but the specific synaptic site of this interaction remains unknown. We wished to investigate the synaptic substrate, and in particular the role of inhibitory signaling, underpinning the behavioral effects of anodal tDCS in homeostatic interactions between anodal tDCS and motor learning. We used transcranial magnetic stimulation (TMS) to investigate cortical excitability and inhibitory signaling following tDCS and motor learning. Each subject participated in four experimental sessions and data were analyzed using repeated measures ANOVAs and post-hoc t-tests as appropriate. As predicted, we found that anodal tDCS prior to the motor task decreased learning rates. This worsening of learning after tDCS was accompanied by a correlated increase in GABAA activity, as measured by TMS-assessed short interval intra-cortical inhibition (SICI). This provides the first direct demonstration in humans that inhibitory synapses are the likely site for the interaction between anodal tDCS and motor learning, and further, that homeostatic plasticity at GABAA synapses has behavioral relevance in humans. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Shaping memory accuracy by left prefrontal transcranial direct current stimulation.

PubMed

Zwissler, Bastian; Sperber, Christoph; Aigeldinger, Sina; Schindler, Sebastian; Kissler, Johanna; Plewnia, Christian

2014-03-12

Human memory is dynamic and flexible but is also susceptible to distortions arising from adaptive as well as pathological processes. Both accurate and false memory formation require executive control that is critically mediated by the left prefrontal cortex (PFC). Transcranial direct current stimulation (tDCS) enables noninvasive modulation of cortical activity and associated behavior. The present study reports that tDCS applied to the left dorsolateral PFC (dlPFC) shaped accuracy of episodic memory via polaritiy-specific modulation of false recognition. When applied during encoding of pictures, anodal tDCS increased whereas cathodal stimulation reduced the number of false alarms to lure pictures in subsequent recognition memory testing. These data suggest that the enhancement of excitability in the dlPFC by anodal tDCS can be associated with blurred detail memory. In contrast, activity-reducing cathodal tDCS apparently acted as a noise filter inhibiting the development of imprecise memory traces and reducing the false memory rate. Consistently, the largest effect was found in the most active condition (i.e., for stimuli cued to be remembered). This first evidence for a polarity-specific, activity-dependent effect of tDCS on false memory opens new vistas for the understanding and potential treatment of disturbed memory control.

Effect of Transcranial Direct Current Stimulation on Severely Affected Arm-Hand Motor Function in Patients After an Acute Ischemic Stroke: A Pilot Randomized Control Trial.

PubMed

Rabadi, Meheroz H; Aston, Christopher E

2017-10-01

The aim of this article was to determine whether cathodal transcranial direct current stimulation (c-tDCS) to unaffected primary motor cortex (PMC) plus conventional occupational therapy (OT) improves functional motor recovery of the affected arm hand in patients after an acute ischemic stroke compared with sham transcranial direct current stimulation plus conventional OT. In this prospective, randomized, double-blinded, sham-controlled trial of 16 severe, acute ischemic stroke patients with severe arm-hand weakness were randomly assigned to either experimental (c-tDCS plus OT; n = 8) or control (sham transcranial direct current stimulation plus OT; n = 8) groups. All patients received a standard 3-hr in-patient rehabilitation therapy, plus an additional ten 30-min sessions of tDCS. During each session, 1 mA of cathodal stimulation to the unaffected PMC is performed followed by the patient's scheduled OT. The primary outcome measure was change in Action Research Arm Test (ARAT) total and subscores on discharge. Application of c-tDCS to unaffected PMC resulted in a clinically relevant 10-point improvement in the affected arm-hand function based on ARAT total score compared with a 2-point improvement in the control group. Application of 30-min of c-tDCS to the unaffected PMC showed a 10-point improvement in the ARAT score. This corresponds to a large effect size in improvement of affected arm-hand function in patients with severe, acute ischemic stroke. Although not statistically significant, this suggests that larger studies, enrolling at least 25 patients in each group, and with a longer follow-up are warranted.

The Use of the Bilingual Aphasia Test for Assessment and Transcranial Direct Current Stimulation to Modulate Language Acquisition in Minimally Verbal Children with Autism

ERIC Educational Resources Information Center

Schneider, Harry D.; Hopp, Jenna P.

2011-01-01

Minimally verbal children with autism commonly demonstrate language dysfunction, including immature syntax acquisition. We hypothesised that transcranial direct current stimulation (tDCS) should facilitate language acquisition in a cohort (n = 10) of children with immature syntax. We modified the English version of the Bilingual Aphasia Test (BAT)…

Sham transcranial electrical stimulation and its effects on corticospinal excitability: a systematic review and meta-analysis.

PubMed

Dissanayaka, Thusharika D; Zoghi, Maryam; Farrell, Michael; Egan, Gary F; Jaberzadeh, Shapour

2018-02-23

Sham stimulation is used in randomized controlled trials (RCTs) to assess the efficacy of active stimulation and placebo effects. It should mimic the characteristics of active stimulation to achieve blinding integrity. The present study was a systematic review and meta-analysis of the published literature to identify the effects of sham transcranial electrical stimulation (tES) - including anodal and cathodal transcranial direct current stimulation (a-tDCS, c-tDCS), transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS) and transcranial pulsed current stimulation (tPCS) - on corticospinal excitability (CSE), compared to baseline in healthy individuals. Electronic databases - PubMed, CINAHL, Scopus, Science Direct and MEDLINE (Ovid) - were searched for RCTs of tES from 1990 to March 2017. Thirty RCTs were identified. Using a random-effects model, meta-analysis of a-tDCS, c-tDCS, tACS, tRNS and tPCS studies showed statistically non-significant pre-post effects of sham interventions on CSE. This review found evidence for statically non-significant effects of sham tES on CSE.

Transcranial Direct Current Stimulation for Treating Depression in a Patient With Right Hemispheric Dominance: A Case Study.

PubMed

Shiozawa, Pedro; da Silva, Mailu Enokibara; Cordeiro, Quirino

2015-09-01

We report the case of a 66-year-old male patient with major depressive disorder for the last 6 months. The patient had been diagnosed with dyslexia during childhood and was left-handed. The intervention protocol consisted in 10 consecutive daily transcranial direct current stimulation sessions. However, after 5 days of stimulation, the patient presented with intensification of depressive symptoms and panic attacks. It was hypothetized that the intensification of symptoms may have been due to stimulation protocol itself. Considering the patient was left-handed and presented comorbidity with dyslexia, there was a plausible hypothesis of right hemispheric dominance. This was corroborated by the Edinburgh Handedness Scale. In fact, dyslexic patients present right hemisphere dominance more frequently. The patient also presented a single photon emission computed tomography with a hypoperfusion area over the left posterior parietal lobe. After the patients agreement, a 10-day experimental repetitive transcranial magnetic stimulation low-frequency protocol over the left dorsolateral prefrontal cortex was started to inhibit the area, which was hypothetically hyperactivated following the rationale of right dominance. The patient presented amelioration of depressive and anxious symptoms. Given the hemispheric reversal we show in the present case study, however, it seems that therapies that are beneficial to right-handers could be detrimental to left-handers.

Pediatric stroke and transcranial direct current stimulation: methods for rational individualized dose optimization

PubMed Central

Gillick, Bernadette T.; Kirton, Adam; Carmel, Jason B.; Minhas, Preet; Bikson, Marom

2014-01-01

Background: Transcranial direct current stimulation (tDCS) has been investigated mainly in adults and doses may not be appropriate in pediatric applications. In perinatal stroke where potential applications are promising, rational adaptation of dosage for children remains under investigation. Objective: Construct child-specific tDCS dosing parameters through case study within a perinatal stroke tDCS safety and feasibility trial. Methods: 10-year-old subject with a diagnosis of presumed perinatal ischemic stroke and hemiparesis was identified. T1 magnetic resonance imaging (MRI) scans used to derive computerized model for current flow and electrode positions. Workflow using modeling results and consideration of dosage in previous clinical trials was incorporated. Prior ad hoc adult montages vs. de novo optimized montages provided distinct risk benefit analysis. Approximating adult dose required consideration of changes in both peak brain current flow and distribution which further tradeoff between maximizing efficacy and adding safety factors. Electrode size, position, current intensity, compliance voltage, and duration were controlled independently in this process. Results: Brain electric fields modeled and compared to values previously predicted models (Datta et al., 2011; Minhas et al., 2012). Approximating conservative brain current flow patterns and intensities used in previous adult trials for comparable indications, the optimal current intensity established was 0.7 mA for 10 min with a tDCS C3/C4 montage. Specifically 0.7 mA produced comparable peak brain current intensity of an average adult receiving 1.0 mA. Electrode size of 5 × 7 cm2 with 1.0 mA and low-voltage tDCS was employed to maximize tolerability. Safety and feasibility confirmed with subject tolerating the session well and no serious adverse events. Conclusion: Rational approaches to dose customization, with steps informed by computational modeling, may improve guidance for pediatric stroke t

Cerebellar transcranial direct current stimulation improves adaptive postural control.

PubMed

Poortvliet, Peter; Hsieh, Billie; Cresswell, Andrew; Au, Jacky; Meinzer, Marcus

2018-01-01

Rehabilitation interventions contribute to recovery of impaired postural control, but it remains a priority to optimize their effectiveness. A promising strategy may involve transcranial direct current stimulation (tDCS) of brain areas involved in fine-tuning of motor adaptation. This study explored the effects of cerebellar tDCS (ctDCS) on postural recovery from disturbance by Achilles tendon vibration. Twenty-eight healthy volunteers participated in this sham-ctDCS controlled study. Standing blindfolded on a force platform, four trials were completed: 60 s quiet standing followed by 20 min active (anodal-tDCS, 1 mA, 20 min, N = 14) or sham-ctDCS (40 s, N = 14) tDCS; three quiet standing trials with 15 s of Achilles tendon vibration and 25 s of postural recovery. Postural steadiness was quantified as displacement, standard deviation and path derived from the center of pressure (COP). Baseline demographics and quiet standing postural steadiness, and backwards displacement during vibration were comparable between groups. However, active-tDCS significantly improved postural steadiness during vibration and reduced forward displacement and variability in COP derivatives during recovery. We demonstrate that ctDCS results in short-term improvement of postural adaptation in healthy individuals. Future studies need to investigate if multisession ctDCS combined with training or rehabilitation interventions can induce prolonged improvement of postural balance. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Adaptive threshold hunting for the effects of transcranial direct current stimulation on primary motor cortex inhibition.

PubMed

Mooney, Ronan A; Cirillo, John; Byblow, Winston D

2018-06-01

Primary motor cortex excitability can be modulated by anodal and cathodal transcranial direct current stimulation (tDCS). These neuromodulatory effects may, in part, be dependent on modulation within gamma-aminobutyric acid (GABA)-mediated inhibitory networks. GABAergic function can be quantified non-invasively using adaptive threshold hunting paired-pulse transcranial magnetic stimulation (TMS). The previous studies have used TMS with posterior-anterior (PA) induced current to assess tDCS effects on inhibition. However, TMS with anterior-posterior (AP) induced current in the brain provides a more robust measure of GABA-mediated inhibition. The aim of the present study was to assess the modulation of corticomotor excitability and inhibition after anodal and cathodal tDCS using TMS with PA- and AP-induced current. In 16 young adults (26 ± 1 years), we investigated the response to anodal, cathodal, and sham tDCS in a repeated-measures double-blinded crossover design. Adaptive threshold hunting paired-pulse TMS with PA- and AP-induced current was used to examine separate interneuronal populations within M1 and their influence on corticomotor excitability and short- and long-interval inhibition (SICI and LICI) for up to 60 min after tDCS. Unexpectedly, cathodal tDCS increased corticomotor excitability assessed with AP (P = 0.047) but not PA stimulation (P = 0.74). SICI AP was reduced after anodal tDCS compared with sham (P = 0.040). Pearson's correlations indicated that SICI AP and LICI AP modulation was associated with corticomotor excitability after anodal (P = 0.027) and cathodal tDCS (P = 0.042). The after-effects of tDCS on corticomotor excitability may depend on the direction of the TMS-induced current used to make assessments, and on modulation within GABA-mediated inhibitory circuits.

Modulation of Isometric Quadriceps Strength in Soccer Players With Transcranial Direct Current Stimulation: A Crossover Study.

PubMed

Vargas, Valentine Z; Baptista, Abrahão F; Pereira, Guilherme O C; Pochini, Alberto C; Ejnisman, Benno; Santos, Marcelo B; João, Silvia M A; Hazime, Fuad A

2018-05-01

Vargas, VZ, Baptista, AF, Pereira, GOC, Pochini, AC, Ejnisman, B, Santos, MB, João, SMA, and Hazime, FA. Modulation of isometric quadriceps strength in soccer players with transcranial direct current stimulation: a crossover study. J Strength Cond Res 32(5): 1336-1341, 2018-The aim of this study was to evaluate the effect of transcranial direct current stimulation (tDCS) on the maximum isometric muscle contraction (MVIC) of the knee extensors in soccer players at the preprofessional level. Twenty female soccer players aged 15-17 years (mean = 16.1; SD = 0.9) with 5.2 ± 2.6 years of training were randomly divided into 2 groups to receive either active or sham tDCS in a single session (2 mA; 0.057 mA·cm). The MVIC of the knee extensors was evaluated in both lower limbs by manual dynamometry in 5 sets of contractions divided into 4 blocks: (a) prestimulation, (b) during tDCS, (c) 30 minutes after tDCS, and (d) 60 minutes after tDCS. After an interval of 7 days, the groups were evaluated again, and the type of initial stimulation was inverted between participants. The MVIC of the knee extensors increased significantly during active tDCS (dominant limb (DL) = 0.4; IC = 0.1-0.8 N·Kg), 30 minutes after active tDCS (DL = 0.9; IC 0.4-1.4 N·Kg), and 60 minutes after active tDCS (DL = 1.0; IC 0.3-1.6 N·Kg) but not for sham tDCS. Our conclusion was that tDCS temporarily increases isometric quadriceps strength in adolescent female soccer players, which may be useful for both strength training and rehabilitation.

Transcranial Direct Current Brain Stimulation Increases Ability to Resist Smoking.

PubMed

Falcone, Mary; Bernardo, Leah; Ashare, Rebecca L; Hamilton, Roy; Faseyitan, Olufunsho; McKee, Sherry A; Loughead, James; Lerman, Caryn

2016-01-01

The ability to exert self-control over temptation is a fundamental component of smoking behavior change. Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits. Although prior studies show that stimulation reduces cigarette craving and self-reported smoking, effects on ability to resist smoking have not been investigated directly. We assessed effects of a single 20-minute session of 1.0 mA anodal stimulation over the left DLPFC with cathodal stimulation over the right supra-orbital area (vs. sham stimulation) on ability to resist smoking in a validated smoking lapse paradigm. Twenty-five participants completed two tDCS sessions (active and sham stimulation) in a within-subject, double-blind, randomized and counterbalanced order with a 2-week washout period. Following overnight abstinence, participants received tDCS in the presence of smoking related cues; they had the option to smoke at any time or receive $1 for every 5 minutes they abstained. After 50 minutes, they participated in a 1 hour ad libitum smoking session. Primary and secondary outcomes were time to first cigarette and cigarette consumption, respectively. In multiple regression models, active tDCS (compared to sham) significantly increased latency to smoke (p = 0.02) and decreased the total number of cigarettes smoked (p = 0.014) during the session. These findings suggest that acute anodal stimulation over the left DLPFC (with cathodal stimulation over the right supra-orbital area) can improve ability to resist smoking, supporting the therapeutic potential of tDCS for smoking cessation treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

PubMed

Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H; Hampstead, Benjamin M; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A; Reis, Janine; Richardson, Jessica D; Rotenberg, Alexander; Turkeltaub, Peter E; Woods, Adam J

2016-01-01

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3-13 A/m(2)) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 milliamperes, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Brazilian Guidelines for transcranial doppler in children and adolescents with sickle cell disease

PubMed Central

Lobo, Clarisse Lopes de Castro; Cançado, Rodolfo Delfini; Leite, Ana Claudia Celestino Bezerra; dos Anjos, Ana Claudia Mendonça; Pinto, Ana Cristina Silva; Matta, Andre Palma da Cunha; Silva, Célia Maria; Silva, Gisele Sampaio; Friedrisch, João Ricardo; Braga, Josefina Aparecida Pellegrini; Lange, Marcos Christiano; Figueiredo, Maria Stella; Rugani, Marília Álvares; Veloso, Orlando; Moura, Patrícia Gomes; Cortez, Paulo Ivo; Adams, Robert; Gualandro, Sandra Fátima Menosi; de Castilho, Shirley Lopes; Thomé, Ursula; Zetola, Viviane Flumignan

2011-01-01

Background Sickle cell disease is the most common monogenic hereditary disease in Brazil. Although strokes are one of the main causes of morbidity and mortality in these patients, the use of transcranial Doppler to identify children at risk is not universally used. Objective To develop Brazilian guidelines for the use of transcranial Doppler in sickle cell disease children and adolescents, so that related health policies can be expanded, and thus contribute to reduce morbidity and mortality. Methods The guidelines were formulated in a consensus meeting of experts in transcranial Doppler and sickle cell disease. The issues discussed were previously formulated and scientific articles in databases (MEDLINE, SciELO and Cochrane) were carefully analyzed. The consensus for each question was obtained by a vote of experts on the specific theme. Results Recommendations were made, including indications for the use of transcranial Doppler according to the sickle cell disease genotype and patients age; the necessary conditions to perform the exam and its periodicity depending on exam results; the criteria for the indication of blood transfusions and iron chelation therapy; the indication of hydroxyurea; and the therapeutic approach in cases of conditional transcranial Doppler. Conclusion The Brazilian guidelines on the use of transcranial doppler in sickle cell disease patients may reduce the risk of strokes, and thus reduce the morbidity and mortality and improve the quality of life of sickle cell disease patients. PMID:23284243

Transcranial Direct Current Stimulation (tDCS): A Beginner's Guide for Design and Implementation

PubMed Central

Thair, Hayley; Holloway, Amy L.; Newport, Roger; Smith, Alastair D.

2017-01-01

Transcranial direct current stimulation (tDCS) is a popular brain stimulation method that is used to modulate cortical excitability, producing facilitatory or inhibitory effects upon a variety of behaviors. There is, however, a current lack of consensus between studies, with many results suggesting that polarity-specific effects are difficult to obtain. This article explores some of these differences and highlights the experimental parameters that may underlie their occurrence. We provide a general, practical snapshot of tDCS methodology, including what it is used for, how to use it, and considerations for designing an effective and safe experiment. Our aim is to equip researchers who are new to tDCS with the essential knowledge so that they can make informed and well-rounded decisions when designing and running successful experiments. By summarizing the varied approaches, stimulation parameters, and outcomes, this article should help inform future tDCS research in a variety of fields. PMID:29213226

Transcranial direct current stimulation over the primary motor vs prefrontal cortex in refractory chronic migraine: A pilot randomized controlled trial.

PubMed

Andrade, Suellen Marinho; de Brito Aranha, Renata Emanuela Lyra; de Oliveira, Eliane Araújo; de Mendonça, Camila Teresa Ponce Leon; Martins, Wanessa Kallyne Nascimento; Alves, Nelson Torro; Fernández-Calvo, Bernardino

2017-07-15

Although transcranial direct current stimulation (tDCS) represents a therapeutic option for the prophylaxis of chronic migraine, the target area for application of the electrical current to the cortex has not yet been well established. Here we sought to determine whether a treatment protocol involving 12 sessions of 2mA, 20min anodal stimulation of the left primary motor (M1) or dorsolateral prefrontal cortex (DLPFC) could offer clinical benefits in the management of pain from migraine. Thirteen participants were assessed before and after treatment, using the Headache Impact Test-6, Visual Analogue Scale and Medical Outcomes Study 36 - Item Short - Form Health Survey. After treatment, group DLPFC exhibited a better performance compared with groups M1 and sham. On intragroup comparison, groups DLPFC and M1 exhibited a greater reduction in headache impact and pain intensity and a higher quality of life after treatment. No significant change was found in group sham. The participants in group M1 exhibited more adverse effects, especially headache, heartburn, and sleepiness, than did those in the other two groups. Transcranial direct current stimulation is a safe and efficacious technique for treating chronic migraine. However, it should be kept in mind that the site of cortical stimulation might modulate the patient's response to treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Evidence of transcranial direct current stimulation-generated electric fields at subthalamic level in human brain in vivo.

PubMed

Chhatbar, Pratik Y; Kautz, Steven A; Takacs, Istvan; Rowland, Nathan C; Revuelta, Gonzalo J; George, Mark S; Bikson, Marom; Feng, Wuwei

2018-03-13

Transcranial direct current stimulation (tDCS) is a promising brain modulation technique for several disease conditions. With this technique, some portion of the current penetrates through the scalp to the cortex and modulates cortical excitability, but a recent human cadaver study questions the amount. This insufficient intracerebral penetration of currents may partially explain the inconsistent and mixed results in tDCS studies to date. Experimental validation of a transcranial alternating current stimulation-generated electric field (EF) in vivo has been performed on the cortical (using electrocorticography, ECoG, electrodes), subcortical (using stereo electroencephalography, SEEG, electrodes) and deeper thalamic/subthalamic levels (using DBS electrodes). However, tDCS-generated EF measurements have never been attempted. We aimed to demonstrate that tDCS generates biologically relevant EF as deep as the subthalamic level in vivo. Patients with movement disorders who have implanted deep brain stimulation (DBS) electrodes serve as a natural experimental model for thalamic/subthalamic recordings of tDCS-generated EF. We measured voltage changes from DBS electrodes and body resistance from tDCS electrodes in three subjects while applying direct current to the scalp at 2 mA and 4 mA over two tDCS montages. Voltage changes at the level of deep nuclei changed proportionally with the level of applied current and varied with different tDCS montages. Our findings suggest that scalp-applied tDCS generates biologically relevant EF. Incorporation of these experimental results may improve finite element analysis (FEA)-based models. Copyright © 2018 Elsevier Inc. All rights reserved.

Polarity-Dependent Misperception of Subjective Visual Vertical during and after Transcranial Direct Current Stimulation (tDCS).

PubMed

Santos-Pontelli, Taiza E G; Rimoli, Brunna P; Favoretto, Diandra B; Mazin, Suleimy C; Truong, Dennis Q; Leite, Joao P; Pontes-Neto, Octavio M; Babyar, Suzanne R; Reding, Michael; Bikson, Marom; Edwards, Dylan J

2016-01-01

Pathologic tilt of subjective visual vertical (SVV) frequently has adverse functional consequences for patients with stroke and vestibular disorders. Repetitive transcranial magnetic stimulation (rTMS) of the supramarginal gyrus can produce a transitory tilt on SVV in healthy subjects. However, the effect of transcranial direct current stimulation (tDCS) on SVV has never been systematically studied. We investigated whether bilateral tDCS over the temporal-parietal region could result in both online and offline SVV misperception in healthy subjects. In a randomized, sham-controlled, single-blind crossover pilot study, thirteen healthy subjects performed tests of SVV before, during and after the tDCS applied over the temporal-parietal region in three conditions used on different days: right anode/left cathode; right cathode/left anode; and sham. Subjects were blind to the tDCS conditions. Montage-specific current flow patterns were investigated using computational models. SVV was significantly displaced towards the anode during both active stimulation conditions when compared to sham condition. Immediately after both active conditions, there were rebound effects. Longer lasting after-effects towards the anode occurred only in the right cathode/left anode condition. Current flow models predicted the stimulation of temporal-parietal regions under the electrodes and deep clusters in the posterior limb of the internal capsule. The present findings indicate that tDCS over the temporal-parietal region can significantly alter human SVV perception. This tDCS approach may be a potential clinical tool for the treatment of SVV misperception in neurological patients.

Monitoring transcranial direct current stimulation induced changes in cortical excitability during the serial reaction time task.

PubMed

Ambrus, Géza Gergely; Chaieb, Leila; Stilling, Roman; Rothkegel, Holger; Antal, Andrea; Paulus, Walter

2016-03-11

The measurement of the motor evoked potential (MEP) amplitudes using single pulse transcranial magnetic stimulation (TMS) is a common method to observe changes in motor cortical excitability. The level of cortical excitability has been shown to change during motor learning. Conversely, motor learning can be improved by using anodal transcranial direct current stimulation (tDCS). In the present study, we aimed to monitor cortical excitability changes during an implicit motor learning paradigm, a version of the serial reaction time task (SRTT). Responses from the first dorsal interosseous (FDI) and forearm flexor (FLEX) muscles were recorded before, during and after the performance of the SRTT. Online measurements were combined with anodal, cathodal or sham tDCS for the duration of the SRTT. Negative correlations between the amplitude of online FDI MEPs and SRTT reaction times (RTs) were observed across the learning blocks in the cathodal condition (higher average MEP amplitudes associated with lower RTs) but no significant differences in the anodal and sham conditions. tDCS did not have an impact on SRTT performance, as would be predicted based on previous studies. The offline before-after SRTT MEP amplitudes showed an increase after anodal and a tendency to decrease after cathodal stimulation, but these changes were not significant. The combination of different interventions during tDCS might result in reduced efficacy of the stimulation that in future studies need further attention. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Modulating Memory Performance in Healthy Subjects with Transcranial Direct Current Stimulation Over the Right Dorsolateral Prefrontal Cortex.

PubMed

Smirni, Daniela; Turriziani, Patrizia; Mangano, Giuseppa Renata; Cipolotti, Lisa; Oliveri, Massimiliano

2015-01-01

The role of the Dorsolateral Prefrontal Cortex (DLPFC) in recognition memory has been well documented in lesion, neuroimaging and repetitive Transcranial Magnetic Stimulation (rTMS) studies. The aim of the present study was to investigate the effects of transcranial Direct Current Stimulation (tDCS) over the left and the right DLPFC during the delay interval of a non-verbal recognition memory task. 36 right-handed young healthy subjects participated in the study. The experimental task was an Italian version of Recognition Memory Test for unknown faces. Study included two experiments: in a first experiment, each subject underwent one session of sham tDCS and one session of left or right cathodal tDCS; in a second experiment each subject underwent one session of sham tDCS and one session of left or right anodal tDCS. Cathodal tDCS over the right DLPFC significantly improved non verbal recognition memory performance, while cathodal tDCS over the left DLPFC had no effect. Anodal tDCS of both the left and right DLPFC did not modify non verbal recognition memory performance. Complementing the majority of previous studies, reporting long term memory facilitations following left prefrontal anodal tDCS, the present findings show that cathodal tDCS of the right DLPFC can also improve recognition memory in healthy subjects.

Anodal transcranial direct current stimulation over the right hemisphere improves auditory comprehension in a case of dementia.

PubMed

Costa, Vanessa; Brighina, Filippo; Piccoli, Tommaso; Realmuto, Sabrina; Fierro, Brigida

2017-01-01

Noninvasive transcranial stimulation methods have been increasingly employed in order to improve cognitive performance in neurological patients. In previous studies with both stroke patients and healthy subjects, noninvasive stimulation of temporal-parietal regions and their homologue produced an improvement in linguistic tasks. The aim of the current study was to evaluate if anodal transcranial direct current stimulation (tDCS) over Brodmann areas 39/40 (angular and supramarginal gyri) could promote the recovery of linguistic functions, in particular comprehension and naming, in a single patient affected by dementia. Three preliminary explorative single sessions (right-side anodal, left-side anodal and sham tDCS) were carried out (Experiment 1). This procedure allows targeting the more effective site of stimulation for the treatment. Subsequently, we carried out a five-days tDCS treatment on the selected hemisphere (Experiment 2). We report verb comprehension amelioration after 5 days of anodal tDCS over the right BAs 39/40 compared with the placebo tDCS. This result is maintained until two weeks after the end of the 5-days treatment. Our findings provide new evidence for the therapeutic use of tDCS in degenerative diseases, suggesting that an explorative study can be useful for targeting the more appropriate stimulation site, and confirm the involvement of right-sided areas associated with language activities.

Transcranial Direct Current Stimulation in Post Stroke Aphasia and Primary Progressive Aphasia: Current Knowledge and Future Clinical Applications

PubMed Central

Sebastian, Rajani; Tsapkini, Kyrana; Tippett, Donna C.

2016-01-01

BACKGROUND The application of transcranial direct current stimulation (tDCS) in chronic post stroke aphasia is documented in a substantial literature, and there is some new evidence that tDCS can augment favorable language outcomes in primary progressive aphasia. Anodal tDCS is most often applied to the left hemisphere language areas to increase cortical excitability (increase the threshold of activation) and cathodal tDCS is most often applied to the right hemisphere homotopic areas to inhibit over activation in contralesional right homologues of language areas. Outcomes usually are based on neuropsychological and language test performance, following a medical model which emphasizes impairment of function, rather than a model which emphasizes functional communication. OBJECTIVE In this paper, we review current literature of tDCS as it is being used as a research tool, and discuss future implementation of tDCS as an adjuvant treatment to behavioral speech-language pathology intervention. METHODS We review literature describing non-invasive brain stimulation, the mechanism of tDCS, and studies of tDCS in aphasia and neurodegenerative disorders. We discuss future clinical applications. RESULTS/CONCLUSIONS tDCS is a promising adjunct to traditional speech-language pathology intervention to address speech-language deficits after stroke and in the neurodegenerative disease, primary progressive aphasia. Limited data are available regarding how performance on these types of specific tasks translates to functional communication outcomes. PMID:27314871

Cathodal transcranial direct current stimulation in children with dystonia: a pilot open-label trial.

PubMed

Young, Scott J; Bertucco, Matteo; Sheehan-Stross, Rebecca; Sanger, Terence D

2013-10-01

Studies suggest that dystonia is associated with increased motor cortex excitability. Cathodal transcranial direct current stimulation can temporarily reduce motor cortex excitability. To test whether stimulation of the motor cortex can reduce dystonic symptoms in children, we measured tracking performance and muscle overflow using an electromyogram tracking task before and after stimulation. Of 10 participants, 3 showed a significant reduction in overflow, and a fourth showed a significant reduction in tracking error. Overflow decreased more when the hand contralateral to the cathode performed the task than when the hand ipsilateral to the cathode performed the task. Averaged over all participants, the results did not reach statistical significance. These results suggest that cathodal stimulation may allow a subset of children to control muscles or reduce involuntary overflow activity. Further testing is needed to confirm these results in a blinded trial and identify the subset of children who are likely to respond.

Transcranial direct current stimulation over the parietal cortex alters bias in item and source memory tasks.

PubMed

Pergolizzi, Denise; Chua, Elizabeth F

2016-10-01

Neuroimaging data have shown that activity in the lateral posterior parietal cortex (PPC) correlates with item recognition and source recollection, but there is considerable debate about its specific contributions. Performance on both item and source memory tasks were compared between participants who were given bilateral transcranial direct current stimulation (tDCS) over the parietal cortex to those given prefrontal or sham tDCS. The parietal tDCS group, but not the prefrontal group, showed decreased false recognition, and less bias in item and source discrimination tasks compared to sham stimulation. These results are consistent with a causal role of the PPC in item and source memory retrieval, likely based on attentional and decision-making biases. Copyright © 2016 Elsevier Inc. All rights reserved.

Transcranial direct current stimulation for hyperactivity and noncompliance in autistic disorder.

PubMed

D'Urso, Giordano; Bruzzese, Dario; Ferrucci, Roberta; Priori, Alberto; Pascotto, Antonio; Galderisi, Silvana; Altamura, Alfredo Carlo; Bravaccio, Carmela

2015-01-01

To evaluate the safety, efficacy, and feasibility of inhibitory transcranial direct current stimulation (tDCS) for the treatment of behavioural abnormalities of autistic patients. Twelve young adult patients with autistic disorder were enrolled. All subjects presented intellectual disability and most of them had speech impairment. The Aberrant Behavior Checklist (ABC) was administered as the primary outcome measure before and after a 2-week tDCS course. All subjects received 10 daily applications of 20 min/1.5 mA/cathodal (inhibitory) tDCS over the left dorso-lateral pre-frontal cortex. Eight out of 10 study completers improved in their abnormal behaviours, reaching an average reduction of 26.7% of the total ABC score. The remaining two patients showed no changes. In the whole group of completers, among the five subscales contributing to the significant reduction of the total score, the most remarkable and statistically significant change was seen in the subscale assessing hyperactivity and non-compliance (-35.9%, P = 0.002). No adverse effects were reported. Inhibitory tDCS improved the ABC rating scores for autistic behaviours. Owing to its ease of use, cost-effectiveness and the limited availability of specific treatment strategies, tDCS might be a valid therapeutic option to be tested in autistic patients.

Using transcranial direct-current stimulation (tDCS) to understand cognitive processing.

PubMed

Reinhart, Robert M G; Cosman, Josh D; Fukuda, Keisuke; Woodman, Geoffrey F

2017-01-01

Noninvasive brain stimulation methods are becoming increasingly common tools in the kit of the cognitive scientist. In particular, transcranial direct-current stimulation (tDCS) is showing great promise as a tool to causally manipulate the brain and understand how information is processed. The popularity of this method of brain stimulation is based on the fact that it is safe, inexpensive, its effects are long lasting, and you can increase the likelihood that neurons will fire near one electrode and decrease the likelihood that neurons will fire near another. However, this method of manipulating the brain to draw causal inferences is not without complication. Because tDCS methods continue to be refined and are not yet standardized, there are reports in the literature that show some striking inconsistencies. Primary among the complications of the technique is that the tDCS method uses two or more electrodes to pass current and all of these electrodes will have effects on the tissue underneath them. In this tutorial, we will share what we have learned about using tDCS to manipulate how the brain perceives, attends, remembers, and responds to information from our environment. Our goal is to provide a starting point for new users of tDCS and spur discussion of the standardization of methods to enhance replicability.

Transcranial direct current stimulation to enhance cognition in euthymic bipolar disorder.

PubMed

Martin, Donel M; Chan, Herng-Nieng; Alonzo, Angelo; Green, Melissa J; Mitchell, Philip B; Loo, Colleen K

2015-12-01

To investigate the use of transcranial direct current stimulation (tDCS) for enhancing working memory and sustained attention in euthymic patients with bipolar disorder. Fifteen patients with bipolar disorder received anodal left prefrontal tDCS with an extracephalic cathode (prefrontal condition), anodal left prefrontal and cathodal cerebellar tDCS (fronto-cerebellar condition), and sham tDCS given 'online' during performance on a working memory and sustained attention task in an intra-individual, cross-over, sham-controlled experimental design. Exploratory cluster analyses examined responders and non-responders for the different active tDCS conditions on both tasks. For working memory, approximately one-third of patients in both active tDCS conditions showed performance improvement. For sustained attention, three of 15 patients showed performance improvement with prefrontal tDCS. Responders to active tDCS for working memory performed more poorly on the task during sham tDCS compared to non-responders. A single session of active prefrontal or fronto-cerebellar tDCS failed to improve working memory or sustained attention performance in euthymic patients with bipolar disorder. Several important considerations are discussed in relation to future studies investigating tDCS for enhancing cognition in patients with bipolar disorder. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Transcranial Direct Current Stimulation for Obsessive-Compulsive Disorder: A Systematic Review

PubMed Central

Brunelin, Jérôme; Bation, Rémy; Saoud, Mohamed; Poulet, Emmanuel

2018-01-01

Despite the advances in psychopharmacology and established psychotherapeutic interventions, more than 40% of patients with obsessive-compulsive disorder (OCD) do not respond to conventional treatment approaches. Transcranial direct current stimulation (tDCS) has been recently proposed as a therapeutic tool to alleviate treatment-resistant symptoms in patients with OCD. The aim of this review was to provide a comprehensive overview of the current state of the art and future clinical applications of tDCS in patients with OCD. A literature search conducted on the PubMed database following PRISMA guidelines and completed by a manual search yielded 12 results: eight case reports, three open-label studies (with 5, 8, and 42 participants), and one randomized trial with two active conditions (12 patients). There was no sham-controlled study. A total of 77 patients received active tDCS with a large diversity of electrode montages mainly targeting the dorsolateral prefrontal cortex, the orbitofrontal cortex or the (pre-) supplementary motor area. Despite methodological limitations and the heterogeneity of stimulation parameters, tDCS appears to be a promising tool to decrease obsessive-compulsive symptoms as well as comorbid depression and anxiety in patients with treatment-resistant OCD. Further sham-controlled studies are needed to confirm these preliminary results. PMID:29495298

Transcranial direct current stimulation in children and adolescents: a comprehensive review.

PubMed

Palm, Ulrich; Segmiller, Felix M; Epple, Ann Natascha; Freisleder, Franz-Joseph; Koutsouleris, Nikolaos; Schulte-Körne, Gerd; Padberg, Frank

2016-10-01

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that has shown promising results in various neuropsychiatric disorders in adults. This review addresses the therapeutic use of tDCS in children and adolescents including safety, ethical, and legal considerations. There are several studies addressing the dosage of tDCS in children and adolescents by computational modeling of electric fields in the pediatric brain. Results suggest halving the amperage used in adults to obtain the same peak electric fields, however, there are some studies reporting on the safe application of tDCS with standard adult parameters in children (2 mA; 20-30 min). There are several randomized placebo controlled trials suggesting beneficial effects of tDCS for the treatment of cerebral palsy. For dystonia there are mixed data. Some studies suggest efficacy of tDCS for the treatment of refractory epilepsy, and for the improvement of attention deficit/hyperactivity disorder and autism. Interestingly, there is a lack of data for the treatment of childhood and adolescent psychiatric disorders, i.e., childhood onset schizophrenia and affective disorders. Overall, tDCS seems to be safe in pediatric population. More studies are needed to confirm the preliminary encouraging results; however, ethical deliberation has to be weighed carefully for every single case.

Systematic evaluation of the impact of stimulation intensity on neuroplastic after-effects induced by transcranial direct current stimulation.

PubMed

Jamil, Asif; Batsikadze, Giorgi; Kuo, Hsiao-I; Labruna, Ludovica; Hasan, Alkomiet; Paulus, Walter; Nitsche, Michael A

2017-02-15

Applications of transcranial direct current stimulation to modulate human neuroplasticity have increased in research and clinical settings. However, the need for longer-lasting effects, combined with marked inter-individual variability, necessitates a deeper understanding of the relationship between stimulation parameters and physiological effects. We systematically investigated the full DC intensity range (0.5-2.0 mA) for both anodal and cathodal tDCS in a sham-controlled repeated measures design, monitoring changes in motor-cortical excitability via transcranial magnetic stimulation up to 2 h after stimulation. For both tDCS polarities, the excitability after-effects did not linearly correlate with increasing DC intensity; effects of lower intensities (0.5, 1.0 mA) showed equal, if not greater effects in motor-cortical excitability. Further, while intra-individual responses showed good reliability, inter-individual sensitivity to TMS accounted for a modest percentage of the variance in the early after-effects of 1.0 mA anodal tDCS, which may be of practical relevance for future optimizations. Contemporary non-invasive neuromodulatory techniques, such as transcranial direct current stimulation (tDCS), have shown promising potential in both restituting impairments in cortical physiology in clinical settings, as well as modulating cognitive abilities in the healthy population. However, neuroplastic after-effects of tDCS are highly dependent on stimulation parameters, relatively short lasting, and not expectedly uniform between individuals. The present study systematically investigates the full range of current intensity between 0.5 and 2.0 mA on left primary motor cortex (M1) plasticity, as well as the impact of individual-level covariates on explaining inter-individual variability. Thirty-eight healthy subjects were divided into groups of anodal and cathodal tDCS. Five DC intensities (sham, 0.5, 1.0, 1.5 and 2.0 mA) were investigated in separate sessions

High definition-transcranial direct current stimulation changes older adults' subjective sleep and corresponding resting-state functional connectivity.

PubMed

Sheng, Jing; Xie, Chao; Fan, Dong-Qiong; Lei, Xu; Yu, Jing

2018-07-01

With advanced age, older adults show functional deterioration in sleep. Transcranial direct current stimulation (tDCS), a noninvasive brain stimulation, modulates individuals' behavioral performance in various cognitive domains. However, the modulation effect and neural mechanisms of tDCS on sleep, especially for the elderly population are not clear. Here, we aimed to investigate whether high-definition transcranial direct current stimulation (HD-tDCS) could modulate community-dwelling older adults' subjective sleep and whether these potential improvements are associated with the large-scale brain activity alterations recorded by functional magnetic resonance imaging. Thirty-one older adults were randomly allocated to the HD-tDCS group and the control group. HD-tDCS was applied for 25 min at 1.5 mA per day for two weeks. The anode electrode was placed over the left dorsolateral prefrontal cortex, surrounded by 4 cathodes at 7 cm radius. All participants completed sleep neuropsychological assessments and fMRI scans individually before and after intervention. Behaviorally, we observed a HD-tDCS-induced enhancement of older adults' sleep duration. On the aspect of the corresponding neural alterations, we observed that HD-tDCS decreased the functional connectivity between the default mode network (DMN) and subcortical network. More importantly, the decoupling connectivity of the DMN-subcortical network was correlated with the improvements of subjective sleep in the HD-tDCS group. Our findings add novel behavioral and neural evidences about tDCS-induced sleep improvement in community-dwelling older adults. With further development, tDCS may be used as an alternative treatment for sleep disorders and alleviate the dysfunction of brain networks induced by aging. Copyright © 2018 Elsevier B.V. All rights reserved.

Successful Treatment of a Drug-Resistant Epilepsy by Long-term Transcranial Direct Current Stimulation: A Case Report.

PubMed

San-Juan, Daniel; Sarmiento, Carlos Ignacio; González, Katia Márquez; Orenday Barraza, José Manuel

2018-01-01

Transcranial direct current stimulation (tDCS) is a reemerged noninvasive cerebral therapy used to treat patients with epilepsy, including focal cortical dysplasia, with controversial results. We present a case of a 28-year-old female with left frontal cortical dysplasia refractory to antiepileptic drugs, characterized by 10-15 daily right tonic hemi-body seizures. The patient received a total of seven sessions of cathodal tDCS (2 mA, 30 min). The first three sessions were applied over three consecutive days, and the remaining four sessions of tDCS were given each at 2-week intervals. At the 1-year follow-up, the patient reported to have a single seizure per month and only mild adverse events.

Non-invasive assessment of cerebral oxygenation: A comparison of retinal and transcranial oximetry

PubMed Central

Van Keer, Jan; Barbosa Breda, João; Nassiri, Vahid; De Deyne, Cathy; Genbrugge, Cornelia; Abegão Pinto, Luís; Stalmans, Ingeborg; Vandewalle, Evelien

2018-01-01

Background To investigate the correlation between cerebral (SO2-transcranial), retinal arterial (SaO2-retinal) and venous (SvO2-retinal) oxygen saturation as measured by near-infrared spectroscopy (NIRS) and retinal oximetry respectively. Methods Paired retinal and cerebral oxygen saturation measurements were performed in healthy volunteers. Arterial and venous retinal oxygen saturation and diameter were measured using a non-invasive spectrophotometric retinal oximeter. Cerebral oxygen saturation was measured using near-infrared spectroscopy. Correlations between SO2-transcranial and retinal oxygen saturation and diameter measurements were assessed using Pearson correlation coefficients. Lin’s concordance correlation coefficient (CCC) and Bland-Altman analysis were performed to evaluate the agreement between SO2-transcranial as measured by NIRS and as estimated using a fixed arterial:venous ratio as 0.3 x SaO2-retinal + 0.7 x SvO2-retinal. The individual relative weight of SaO2-retinal and SvO2-retinal to obtain the measured SO2-transcranial was calculated for all subjects. Results Twenty-one healthy individuals aged 26.4 ± 2.2 years were analyzed. SO2-transcranial was positively correlated with both SaO2-retinal and SvO2-retinal (r = 0.44, p = 0.045 and r = 0.43, p = 0.049 respectively) and negatively correlated with retinal venous diameter (r = -0.51, p = 0.017). Estimated SO2-transcranial based on retinal oximetry showed a tolerance interval of (-13.70 to 14.72) and CCC of 0.46 (95% confidence interval: 0.05 to 0.73) with measured SO2-transcranial. The average relative weights of SaO2-retinal and SvO2-retinal to obtain SO2-transcranial were 0.31 ± 0.11 and 0.69 ± 0.11, respectively. Conclusion This is the first study to show the correlation between retinal and cerebral oxygen saturation, measured by NIRS and retinal oximetry. The average relative weight of arterial and venous retinal oxygen saturation to obtain the measured transcranial oxygen saturation as

Polarity-Dependent Misperception of Subjective Visual Vertical during and after Transcranial Direct Current Stimulation (tDCS)

PubMed Central

Santos-Pontelli, Taiza E. G.; Rimoli, Brunna P.; Favoretto, Diandra B.; Mazin, Suleimy C.; Truong, Dennis Q.; Leite, Joao P.; Pontes-Neto, Octavio M.; Babyar, Suzanne R.; Reding, Michael; Bikson, Marom; Edwards, Dylan J.

2016-01-01

Pathologic tilt of subjective visual vertical (SVV) frequently has adverse functional consequences for patients with stroke and vestibular disorders. Repetitive transcranial magnetic stimulation (rTMS) of the supramarginal gyrus can produce a transitory tilt on SVV in healthy subjects. However, the effect of transcranial direct current stimulation (tDCS) on SVV has never been systematically studied. We investigated whether bilateral tDCS over the temporal-parietal region could result in both online and offline SVV misperception in healthy subjects. In a randomized, sham-controlled, single-blind crossover pilot study, thirteen healthy subjects performed tests of SVV before, during and after the tDCS applied over the temporal-parietal region in three conditions used on different days: right anode/left cathode; right cathode/left anode; and sham. Subjects were blind to the tDCS conditions. Montage-specific current flow patterns were investigated using computational models. SVV was significantly displaced towards the anode during both active stimulation conditions when compared to sham condition. Immediately after both active conditions, there were rebound effects. Longer lasting after-effects towards the anode occurred only in the right cathode/left anode condition. Current flow models predicted the stimulation of temporal-parietal regions under the electrodes and deep clusters in the posterior limb of the internal capsule. The present findings indicate that tDCS over the temporal-parietal region can significantly alter human SVV perception. This tDCS approach may be a potential clinical tool for the treatment of SVV misperception in neurological patients. PMID:27031726

Feasibility and Clinical Utility of High-definition Transcranial Direct Current Stimulation in the Treatment of Persistent Hallucinations in Schizophrenia.

PubMed

Bose, A; Shivakumar, V; Chhabra, H; Parlikar, R; Sreeraj, V S; Dinakaran, D; Narayanaswamy, J C; Venkatasubramanian, G

2017-12-01

Persistent auditory verbal hallucination is a clinically significant problem in schizophrenia. Recent studies suggest a promising role for add-on transcranial direct current stimulation (tDCS) in treatment. An optimised version of tDCS, namely high-definition tDCS (HD-tDCS), uses smaller electrodes arranged in a 4x1 ring configuration and may offer more focal and predictable neuromodulation than conventional tDCS. This case report illustrates the feasibility and clinical utility of add-on HD-tDCS over the left temporoparietal junction in a 4x1 ring configuration to treat persistent auditory verbal hallucination in schizophrenia.

Visualizing Transcranial Direct Current Stimulation (tDCS) in vivo using Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Jog, Mayank Anant

Transcranial Direct Current Stimulation (tDCS) is a low-cost, non-invasive neuromodulation technique that has been shown to treat clinical symptoms as well as improve cognition. However, no techniques exist at the time of research to visualize tDCS currents in vivo. This dissertation presents the theoretical framework and experimental implementations of a novel MRI technique that enables non-invasive visualization of the tDCS electric current using magnetic field mapping. The first chapter establishes the feasibility of measuring magnetic fields induced by tDCS currents. The following chapter discusses the state of the art implementation that can measure magnetic field changes in individual subjects undergoing concurrent tDCS/MRI. The final chapter discusses how the developed technique was integrated with BOLD fMRI-an established MRI technique for measuring brain function. By enabling a concurrent measurement of the tDCS current induced magnetic field as well as the brain's hemodynamic response to tDCS, our technique opens a new avenue to investigate tDCS mechanisms and improve targeting.

Relationship of herpes simplex encephalitis and transcranial direct current stimulation--a case report.

PubMed

Yang, Yuanbin; Xiao, Juan; Song, Haiqing; Wang, Ralph; Hussain, Mohammed; Song, Weiqun

2015-04-01

We report a rare case of relapsing herpes simplex encephalitis in a-37-year-old patient which was previously confirmed by positive polymerase chain reaction, herpes simplex virus (HSV) type1 IgG antibodies in cerebrospinal fluid and characterized on MRI. During the first admission, he was treated with continuous acyclovir treatment for one month with clinical improvement except for residual aphasia, for which he received a course of outpatient transcranial direct current stimulation (tDCS). A constant current of 1.2 mA was applied for 20 min twice daily. After the 4th day the patient was found to be irritable and uncooperative by staff and family members. A subsequent MRI showed significant deterioration of the lesion on comparison to the first MRI which led to discontinuation of tDCS.The relatively rapid exacerbation of HSV in only a few days is unusual. Our aim is to discuss if tDCS is related to HSV relapse and in doing so highlight possible mechanisms. Copyright © 2015. Published by Elsevier B.V.

Improved reading measures in adults with dyslexia following transcranial direct current stimulation treatment.

PubMed

Heth, Inbahl; Lavidor, Michal

2015-04-01

To better understand the contribution of the dorsal system to word reading, we explored transcranial direct current stimulation (tDCS) effects when adults with developmental dyslexia received active stimulation over the visual extrastriate area MT/V5, which is dominated by magnocellular input. Stimulation was administered in 5 sessions spread over two weeks, and reading speed and accuracy as well as reading fluency were assessed before, immediately after, and a week after the end of the treatment. A control group of adults with developmental dyslexia matched for age, gender, reading level, vocabulary and block-design WAIS-III sub-tests and reading level was exposed to the same protocol but with sham stimulation. The results revealed that active, but not sham stimulation, significantly improved reading speed and fluency. This finding suggests that the dorsal stream may play a role in efficient retrieval from the orthographic input lexicon in the lexical route. It also underscores the potential of tDCS as an intervention tool for improving reading speed, at least in adults with developmental dyslexia. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transcranial direct current stimulation in mild cognitive impairment: Behavioral effects and neural mechanisms.

PubMed

Meinzer, Marcus; Lindenberg, Robert; Phan, Mai Thy; Ulm, Lena; Volk, Carina; Flöel, Agnes

2015-09-01

The long preclinical phase of Alzheimer's disease provides opportunities for potential disease-modifying interventions in prodromal stages such as mild cognitive impairment (MCI). Anodal transcranial direct current stimulation (anodal-tDCS), with its potential to enhance neuroplasticity, may allow improving cognition in MCI. In a double-blind, cross-over, sham-controlled study, anodal-tDCS was administered to the left inferior frontal cortex during task-related and resting-state functional magnetic resonance imaging (fMRI) to assess its impact on cognition and brain functions in MCI. During sham stimulation, MCI patients produced fewer correct semantic-word-retrieval responses than matched healthy controls, which was associated with hyperactivity in bilateral prefrontal regions. Anodal-tDCS significantly improved performance to the level of controls, reduced task-related prefrontal hyperactivity and resulted in "normalization" of abnormal network configuration during resting-state fMRI. Anodal-tDCS exerts beneficial effects on cognition and brain functions in MCI, thereby providing a framework to test whether repeated stimulation sessions may yield sustained reversal of cognitive deficits. Copyright © 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Bilateral Transcranial Direct Current Stimulation Reshapes Resting-State Brain Networks: A Magnetoencephalography Assessment

PubMed Central

Turco, Cristina; Di Pino, Giovanni; Arcara, Giorgio

2018-01-01

Transcranial direct current stimulation (tDCS) can noninvasively induce brain plasticity, and it is potentially useful to treat patients affected by neurological conditions. However, little is known about tDCS effects on resting-state brain networks, which are largely involved in brain physiological functions and in diseases. In this randomized, sham-controlled, double-blind study on healthy subjects, we have assessed the effect of bilateral tDCS applied over the sensorimotor cortices on brain and network activity using a whole-head magnetoencephalography system. Bilateral tDCS, with the cathode (−) centered over C4 and the anode (+) centered over C3, reshapes brain networks in a nonfocal fashion. Compared to sham stimulation, tDCS reduces left frontal alpha, beta, and gamma power and increases global connectivity, especially in delta, alpha, beta, and gamma frequencies. The increase of connectivity is consistent across bands and widespread. These results shed new light on the effects of tDCS and may be of help in personalizing treatments in neurological disorders. PMID:29593782

Intra-Subject Consistency and Reliability of Response Following 2 mA Transcranial Direct Current Stimulation.

PubMed

Dyke, Katherine; Kim, Soyoung; Jackson, Georgina M; Jackson, Stephen R

Transcranial direct current stimulation (tDCS) is a popular non-invasive brain stimulation technique that has been shown to influence cortical excitability. While polarity specific effects have often been reported, this is not always the case, and variability in both the magnitude and direction of the effects have been observed. We aimed to explore the consistency and reliability of the effects of tDCS by investigating changes in cortical excitability across multiple testing sessions in the same individuals. A within subjects design was used to investigate the effects of anodal and cathodal tDCS applied to the motor cortex. Four experimental sessions were tested for each polarity in addition to two sham sessions. Transcranial magnetic stimulation (TMS) was used to measure cortical excitability (TMS recruitment curves). Changes in excitability were measured by comparing baseline measures and those taken immediately following 20 minutes of 2 mA stimulation or sham stimulation. Anodal tDCS significantly increased cortical excitability at a group level, whereas cathodal tDCS failed to have any significant effects. The sham condition also failed to show any significant changes. Analysis of intra-subject responses to anodal stimulation across four sessions suggest that the amount of change in excitability across sessions was only weakly associated, and was found to have poor reliability across sessions (ICC = 0.276). The effects of cathodal stimulation show even poorer reliability across sessions (ICC = 0.137). In contrast ICC analysis for the two sessions of sham stimulation reflect a moderate level of reliability (ICC = .424). Our findings indicate that although 2 mA anodal tDCS is effective at increasing cortical excitability at group level, the effects are unreliable across repeated testing sessions within individual participants. Our results suggest that 2 mA cathodal tDCS does not significantly alter cortical excitability immediately following

Transcranial Direct Current Stimulation in Child and Adolescent Psychiatry.

PubMed

Muszkat, Débora; Polanczyk, Guilherme Vanoni; Dias, Taciana G Costa; Brunoni, André Russowsky

2016-09-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that consists of applying a weak electric current over the scalp to modulate cortical excitability. tDCS has been extensively investigated in adults with psychiatric disorders. The aim of this study was to review the current literature regarding the use of tDCS in children and adolescents with psychiatric disorders. We searched MEDLINE and EMBASE databases for studies evaluating the safety and efficacy of tDCS in children and adolescents from age 0 to 18 years with psychiatric disorders. We found six studies that evaluated patients with different psychiatric disorders, with diverse study designs and stimulation parameters, including three small randomized clinical trials (RCTs), one evaluating childhood-onset schizophrenia, one RCT with patients with autism spectrum disorders (ASD), and one study in attention-deficit/hyperactivity disorder (ADHD); three open-label studies, two evaluating patients with ASD, and one study of feasibility of the technique in children and adolescents with language disorders and diverse psychiatric disorders, including ASD, intellectual disability, and ADHD. We also found three studies of dosage considerations in the general pediatric population. The technique was well tolerated, with no reports of serious side effects. Preliminary research suggests that tDCS may be well tolerated and safe for children and adolescents with psychiatric and neurodevelopmental disorders. Nevertheless, because the literature regarding tDCS in child and adolescent psychiatry is scarce and there exist limited numbers of randomized controlled trials, it is not possible to draw definite conclusions. Future studies should investigate the technique with regard to specific psychiatric conditions in comparison with standard treatments. In addition, long-term efficacy and safety should be monitored.

Long term clinical and neurophysiological effects of cerebellar transcranial direct current stimulation in patients with neurodegenerative ataxia.

PubMed

Benussi, Alberto; Dell'Era, Valentina; Cotelli, Maria Sofia; Turla, Marinella; Casali, Carlo; Padovani, Alessandro; Borroni, Barbara

Neurodegenerative cerebellar ataxias represent a group of disabling disorders for which we currently lack effective therapies. Cerebellar transcranial direct current stimulation (tDCS) is a non-invasive technique, which has been demonstrated to modulate cerebellar excitability and improve symptoms in patients with cerebellar ataxias. The present study investigated whether a two-weeks' treatment with cerebellar anodal tDCS could improve symptoms in patients with neurodegenerative cerebellar ataxia and could modulate cerebello-motor connectivity, at short and long term. We performed a double-blind, randomized, sham controlled trial with cerebellar tDCS (5 days/week for 2 weeks) in twenty patients with ataxia. Each patient underwent a clinical evaluation pre- and post-anodal tDCS or sham stimulation. A follow-up evaluation was performed at one and three months. Cerebello-motor connectivity was evaluated using transcranial magnetic stimulation (TMS) at baseline and at follow-up. Patients who underwent anodal tDCS showed a significant improvement in all performance scores (scale for the assessment and rating of ataxia, international cooperative ataxia rating scale, 9-hole peg test, 8-m walking time) and in cerebellar brain inhibition compared to patients who underwent sham stimulation. A two-weeks' treatment with anodal cerebellar tDCS improves symptoms in patients with ataxia and restores physiological cerebellar brain inhibition pathways. Cerebellar tDCS might represent a promising future therapeutic and rehabilitative approach in patients with neurodegenerative ataxia. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Transcranial Direct Current Stimulation, Transcranial Pulsed Current Stimulation, and Their Combination on Brain Oscillations in Patients with Chronic Visceral Pain: A Pilot Crossover Randomized Controlled Study.

PubMed

Thibaut, Aurore; Russo, Cristina; Hurtado-Puerto, Aura Maria; Morales-Quezada, Jorge Leon; Deitos, Alícia; Petrozza, John Christopher; Freedman, Steven; Fregni, Felipe

2017-01-01

Chronic visceral pain (CVP) syndromes are persistently painful disorders with a remarkable lack of effective treatment options. This study aimed at evaluating the effects of different neuromodulation techniques in patients with CVP on cortical activity, through electreocephalography (EEG) and on pain perception, through clinical tests. A pilot crossover randomized controlled study. Out-patient. Adults with CVP (>3 months). Participants received four interventions in a randomized order: (1) transcranial pulsed current stimulation (tPCS) and active transcranial direct current stimulation (tDCS) combined, (2) tPCS alone, (3) tDCS alone, and (4) sham condition. Resting state quantitative electroencephalography (qEEG) and pain assessments were performed before and after each intervention. Results were compared with a cohort of 47 healthy controls. We enrolled six patients with CVP for a total of 21 visits completed. Compared with healthy participants, patients with CVP showed altered cortical activity characterized by increased power in theta, alpha and beta bands, and a significant reduction in the alpha/beta ratio. Regarding tES, the combination of tDCS with tPCS had no effect on power in any of the bandwidths, nor brain regions. Comparing tPCS with tDCS alone, we found that tPCS induced higher increase in power within the theta and alpha bandwidths. This study confirms that patients with CVP present abnormal EEG-indexed cortical activity compared with healthy controls. Moreover, we showed that combining two types of neurostimulation techniques had no effect, whereas the two interventions, when applied individually, have different neural signatures.

The effect of current flow direction on motor hot spot allocation by transcranial magnetic stimulation.

PubMed

Stephani, Caspar; Paulus, Walter; Sommer, Martin

2016-01-01

The objective of this study was to investigate the significance of pulse configurations and current direction for corticospinal activation using transcranial magnetic stimulation (TMS). In 11 healthy subjects (8 female), a motor map for the motor evoked potentials (MEPs) recorded from the first dorsal interosseus (FDI), abductor digiti minimi (ADM), extensor carpi radialis, and biceps brachii (BB) muscles of the dominant side was established. Starting from a manually determined hot spot of the FDI representation, we measured MEPs at equal oriented points on an hexagonal grid, with 7 MEPs recorded at each point, using the following pulse configurations: posteriorly directed monophasic (Mo-P), anteriorly directed monophasic (Mo-A), biphasic with the more relevant second cycle oriented posteriorly (Bi-P) as well as a reversed biphasic condition (Bi-A). For each pulse configuration, a hot spot was determined and a center of gravity (CoG) was calculated. We found that the factor current direction had an effect on location of the CoG-adjusted hot spot in the cranio-caudal axis but not in the latero-medial direction with anteriorly directed pulses locating the CoG more anteriorly and vice versa. In addition, the CoG for the FDI was more laterally than the cortical representations for the abductor digiti minimi (ADM) and extensor carpi radialis (ECR) which were registered as well. The results indicate that direction of the current pulse should be taken into account for determination of the motor representation of a muscle by TMS. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Successful Treatment of a Drug-Resistant Epilepsy by Long-term Transcranial Direct Current Stimulation: A Case Report

PubMed Central

San-Juan, Daniel; Sarmiento, Carlos Ignacio; González, Katia Márquez; Orenday Barraza, José Manuel

2018-01-01

Transcranial direct current stimulation (tDCS) is a reemerged noninvasive cerebral therapy used to treat patients with epilepsy, including focal cortical dysplasia, with controversial results. We present a case of a 28-year-old female with left frontal cortical dysplasia refractory to antiepileptic drugs, characterized by 10–15 daily right tonic hemi-body seizures. The patient received a total of seven sessions of cathodal tDCS (2 mA, 30 min). The first three sessions were applied over three consecutive days, and the remaining four sessions of tDCS were given each at 2-week intervals. At the 1-year follow-up, the patient reported to have a single seizure per month and only mild adverse events. PMID:29479337

Using transcranial direct-current stimulation (tDCS) to understand cognitive processing

PubMed Central

Reinhart, Robert M.G.; Cosman, Josh D.; Fukuda, Keisuke; Woodman, Geoffrey F.

2017-01-01

Noninvasive brain stimulation methods are becoming increasingly common tools in the kit of the cognitive scientist. In particular, transcranial direct-current stimulation (tDCS) is showing great promise as a tool to causally manipulate the brain and understand how information is processed. The popularity of this method of brain stimulation is based on the fact that it is safe, inexpensive, its effects are long lasting, and you can increase the likelihood that neurons will fire near one electrode and decrease the likelihood that neurons will fire near another. However, this method of manipulating the brain to draw causal inferences is not without complication. Because tDCS methods continue to be refined and are not yet standardized, there are reports in the literature that show some striking inconsistencies. Primary among the complications of the technique is that the tDCS method uses two or more electrodes to pass current and all of these electrodes will have effects on the tissue underneath them. In this tutorial, we will share what we have learned about using tDCS to manipulate how the brain perceives, attends, remembers, and responds to information from our environment. Our goal is to provide a starting point for new users of tDCS and spur discussion of the standardization of methods to enhance replicability. PMID:27804033

Contribution of transcranial direct current stimulation on inhibitory control to assess the neurobiological aspects of attention deficit hyperactivity disorder: randomized controlled trial.

PubMed

Cosmo, Camila; Baptista, Abrahão Fontes; de Sena, Eduardo Pondé

2015-05-18

The applicability of transcranial direct current stimulation (tDCS) in individuals with attention deficit hyperactivity disorder (ADHD) has not yet been investigated. This low-cost, non-invasive, and safe technique optimized to modulate the inhibitory response might be a useful treatment option for those affected by this condition. The aim of this single center, parallel, randomized, double-blinded, sham-controlled trial is to investigate the efficacy of transcranial direct current stimulation over the prefrontal cortex on the modulation of inhibitory control in adults with attention deficit hyperactivity disorder. A total of 60 individuals will be divided into 2 groups by block randomization to receive active or sham stimulation. Anodal stimulation over the left dorsolateral prefrontal cortex will be applied at 1 mA during a single 20-minute session. Before and after interventions, subjects will perform 2 go/no go tasks and the brain electrical activity will be recorded by electroencephalogram (EEG) with 32 channels, according to the 10-20 international EEG system. The trial began in May 2013 and we are currently performing the statistical analysis for the secondary outcomes. The findings from this study will provide preliminary results about the role of prefrontal cortex activation through tDCS on ADHD patients. Clinicaltrials.gov NCT01968512; http://clinicaltrials.gov/ct2/show/NCT01968512 (Archived by WebCite at www.webcitation.org/6YMSW2tkD).

Transcranial direct current stimulation reduces food-craving and measures of hyperphagia behavior in participants with Prader-Willi syndrome.

PubMed

Bravo, Gabriela L; Poje, Albert B; Perissinotti, Iago; Marcondes, Bianca F; Villamar, Mauricio F; Manzardo, Ann M; Luque, Laura; LePage, Jean F; Stafford, Diane; Fregni, Felipe; Butler, Merlin G

2016-03-01

Prader-Willi syndrome (PWS) is a neurodevelopmental genetic disorder characterized by intellectual disabilities and insatiable appetite with compulsive eating leading to severe obesity with detrimental health consequences. Transcranial direct current stimulation (tDCS) has been shown to modulate decision-making and cue-induced food craving in healthy adults. We conducted a pilot double blind, sham-controlled, multicenter study of tDCS modulation of food drive and craving in 10 adult PWS participants, 11 adult obese (OB) and 11 adult healthy-weight control (HWC) subjects. PWS and OB subjects received five consecutive daily sessions of active or sham tDCS over the right dorsolateral prefrontal cortex (DLPFC), while HWC received a single sham and active tDCS in a crossover design. Standardized psychometric instruments assessed food craving, drive and hyperphagia by self-report and caregiver assessment over 30 days. Robust baseline differences were observed in severity scores for the Three-Factor Eating Questionnaire (TFEQ) and Dykens Hyperphagia Questionnaire (DHQ) for PWS compared to HWC while obese participants were more similar to HWC. Active tDCS stimulation in PWS was associated with a significant change from baseline in TFEQ Disinhibition (Factor II) (Ƶ = 1.9, P < 0.05, 30 days) and Total Scores (Ƶ = 2.3, P < 0.02, 30 days), and participant ratings of the DHQ Severity (Ƶ = 1.8, P < 0.06, 5 days) and Total Scores (Ƶ = 1.9, P < 0.05, 15 days). These findings support sustained neuromodulatory effects and efficacy of tDCS to reduce food drive and behaviors impacting hyperphagia in PWS. Transcranial direct current stimulation may represent a straight-forward, low risk and low cost method to improve care, management and quality of life in PWS. © 2015 Wiley Periodicals, Inc.

Augmentation of Fear Extinction by Transcranial Direct Current Stimulation (tDCS)

PubMed Central

Dittert, Natalie; Hüttner, Sandrina; Polak, Thomas; Herrmann, Martin J.

2018-01-01

Although posttraumatic stress disorder (PTSD; DSM-V 309.82) and anxiety disorders (DSM-V 300.xx) are widely spread mental disorders, the effectiveness of their therapy is still unsatisfying. Non-invasive brain-stimulation techniques like transcranial direct current stimulation (tDCS) might be an option to improve extinction learning, which is a main functional factor of exposure-based therapy for anxiety disorders. To examine this hypothesis, we used a fear conditioning paradigm with female faces as conditioned stimuli (CS) and a 95-dB female scream as unconditioned stimulus (UCS). We aimed to perform a tDCS of the ventromedial prefrontal cortex (vmPFC), which is mainly involved in the control of extinction-processes. Therefore, we applied two 4 × 4 cm electrodes approximately at the EEG-positions F7 and F8 and used a direct current of 1.5 mA. The 20-min stimulation was started during a 10-min break between acquisition and extinction and went on overall extinction-trials. The healthy participants were randomly assigned in two double-blinded process into two sham stimulation and two verum stimulation groups with opposite current flow directions. To measure the fear reactions, we used skin conductance responses (SCR) and subjective ratings. We performed a generalized estimating equations model for the SCR to assess the impact of tDCS and current flow direction on extinction processes for all subjects that showed a successful conditioning (N = 84). The results indicate that tDCS accelerates early extinction processes with a significantly faster loss of CS+/CS– discrimination. The discrimination loss was driven by a significant decrease in reaction toward the CS+ as well as an increase in reaction toward the CS– in the tDCS verum groups, whereas the sham groups showed no significant reaction changes during this period. Therefore, we assume that tDCS of the vmPFC can be used to enhance early extinction processes successfully. But before it should be tested in a

The influence of current direction on phosphene thresholds evoked by transcranial magnetic stimulation.

PubMed

Kammer, T; Beck, S; Erb, M; Grodd, W

2001-11-01

To quantify phosphene thresholds evoked by transcranial magnetic stimulation (TMS) in the occipital cortex as a function of induced current direction. Phosphene thresholds were determined in 6 subjects. We compared two stimulator types (Medtronic-Dantec and Magstim) with monophasic pulses using the standard figure-of-eight coils and systematically varied hemisphere (left and right) and induced current direction (latero-medial and medio-lateral). Each measurement was made 3 times, with a new stimulation site chosen for each repetition. Only those stimulation sites were investigated where phosphenes were restricted to one visual hemifield. Coil positions were stereotactically registered. Functional magnetic resonance imaging (fMRI) of retinotopic areas was performed in 5 subjects to individually characterize the borders of visual areas; TMS stimulation sites were coregistered with respect to visual areas. Despite large interindividual variance we found a consistent pattern of phosphene thresholds. They were significantly lower if the direction of the induced current was oriented from lateral to medial in the occipital lobe rather than vice versa. No difference with respect to the hemisphere was found. Threshold values normalized to the square root of the stored energy in the stimulators were lower with the Medtronic-Dantec device than with the Magstim device. fMRI revealed that stimulation sites generating unilateral phosphenes were situated at V2 and V3. Variability of phosphene thresholds was low within a cortical patch of 2x2cm(2). Stimulation over V1 yields phosphenes in both visual fields. The excitability of visual cortical areas depends on the direction of the induced current with a preference for latero-medial currents. Although the coil positions used in this study were centered over visual areas V2 and V3, we cannot rule out the possibility that subcortical structures or V1 could actually be the main generator for phosphenes.

In-vivo Imaging of Magnetic Fields Induced by Transcranial Direct Current Stimulation (tDCS) in Human Brain using MRI

NASA Astrophysics Data System (ADS)

Jog, Mayank V.; Smith, Robert X.; Jann, Kay; Dunn, Walter; Lafon, Belen; Truong, Dennis; Wu, Allan; Parra, Lucas; Bikson, Marom; Wang, Danny J. J.

2016-10-01

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that applies mA currents at the scalp to modulate cortical excitability. Here, we present a novel magnetic resonance imaging (MRI) technique, which detects magnetic fields induced by tDCS currents. This technique is based on Ampere’s law and exploits the linear relationship between direct current and induced magnetic fields. Following validation on a phantom with a known path of electric current and induced magnetic field, the proposed MRI technique was applied to a human limb (to demonstrate in-vivo feasibility using simple biological tissue) and human heads (to demonstrate feasibility in standard tDCS applications). The results show that the proposed technique detects tDCS induced magnetic fields as small as a nanotesla at millimeter spatial resolution. Through measurements of magnetic fields linearly proportional to the applied tDCS current, our approach opens a new avenue for direct in-vivo visualization of tDCS target engagement.

Clinically Effective Treatment of Fibromyalgia Pain With High-Definition Transcranial Direct Current Stimulation: Phase II Open-Label Dose Optimization.

PubMed

Castillo-Saavedra, Laura; Gebodh, Nigel; Bikson, Marom; Diaz-Cruz, Camilo; Brandao, Rivail; Coutinho, Livia; Truong, Dennis; Datta, Abhishek; Shani-Hershkovich, Revital; Weiss, Michal; Laufer, Ilan; Reches, Amit; Peremen, Ziv; Geva, Amir; Parra, Lucas C; Fregni, Felipe

2016-01-01

Despite promising preliminary results in treating fibromyalgia (FM) pain, no neuromodulation technique has been adopted in clinical practice because of limited efficacy, low response rate, or poor tolerability. This phase II open-label trial aims to define a methodology for a clinically effective treatment of pain in FM by establishing treatment protocols and screening procedures to maximize efficacy and response rate. High-definition transcranial direct current stimulation (HD-tDCS) provides targeted subthreshold brain stimulation, combining tolerability with specificity. We aimed to establish the number of HD-tDCS sessions required to achieve a 50% FM pain reduction, and to characterize the biometrics of the response, including brain network activation pain scores of contact heat-evoked potentials. We report a clinically significant benefit of a 50% pain reduction in half (n = 7) of the patients (N = 14), with responders and nonresponders alike benefiting from a cumulative effect of treatment, reflected in significant pain reduction (P = .035) as well as improved quality of life (P = .001) over time. We also report an aggregate 6-week response rate of 50% of patients and estimate 15 as the median number of HD-tDCS sessions to reach clinically meaningful outcomes. The methodology for a pivotal FM neuromodulation clinical trial with individualized treatment is thus supported. Registered in Clinicaltrials.gov under registry number NCT01842009. In this article, an optimized protocol for the treatment of fibromyalgia pain with targeted subthreshold brain stimulation using high-definition transcranial direct current stimulation is outlined. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

Effects of prefrontal bipolar and high-definition transcranial direct current stimulation on cortical reactivity and working memory in healthy adults.

PubMed

Hill, Aron T; Rogasch, Nigel C; Fitzgerald, Paul B; Hoy, Kate E

2017-05-15

Transcranial direct current stimulation (tDCS) is a well-recognised neuromodulatory technology which has been shown to induce short-lasting changes in motor-cortical excitability. The recent and rapid expansion of tDCS into the cognitive domain, however, necessitates deeper mechanistic understanding of its neurophysiological effects over non-motor brain regions. The present study utilised transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) to probe the immediate and longer-term effects of both a bipolar (BP-tDCS) and more focal 4×1 High-Definition tDCS (HD-tDCS) montage applied over the left DLPFC on TMS-evoked potentials (TEPs) and oscillations in 19 healthy adult participants. 2-back working memory (WM) performance was also assessed as a marker of cognitive function. Region of interest (ROI) analyses taken from the F1 electrode directly adjacent to the stimulation site revealed increased P60 TEP amplitudes at this location 5min following BP-tDCS and 30min following HD-tDCS. Further global cluster based analyses of all scalp electrodes revealed widespread neuromodulatory changes following HD-tDCS, but not BP-tDCS, both five and 30min after stimulation, with reductions also detected in both beta and gamma oscillatory power over parieto-occipital channels 30min after stimulation. No significant changes in WM performance were observed following either HD-tDCS or BP-tDCS. This study highlights the capacity for single-session prefrontal anodal tDCS montages to modulate neurophysiological processes, as assessed with TMS-EEG. Copyright © 2017 Elsevier Inc. All rights reserved.

Prefrontal transcranial direct current stimulation improves fundamental vehicle control abilities.

PubMed

Sakai, Hiroyuki; Uchiyama, Yuji; Tanaka, Satoshi; Sugawara, Sho K; Sadato, Norihiro

2014-10-15

Noninvasive brain stimulation techniques have increasingly attracted the attention of neuroscientists because they enable the identification of the causal role of a targeted brain region. However, few studies have applied such techniques to everyday life situations. Here, we investigate the causal role of the dorsolateral prefrontal cortex (DLPFC) in fundamental vehicle control abilities. Thirteen participants underwent a simulated driving task under prefrontal transcranial direct current stimulation (tDCS) on three separate testing days. Each testing day was randomly assigned to either anodal over the right with cathodal over the left DLPFC, cathodal over the right with anodal over the left DLPFC, or sham stimulation. The driving task required the participants to maintain an inter-vehicle distance to a leading car traveling a winding road with a constant speed. Driving performance was quantified using two metrics: the root-mean-square error of inter-vehicle distance as car-following performance, and the standard deviation of lateral position as lane-keeping performance. Results showed that both car-following and lane-keeping performances were significantly greater for right anodal/left cathodal compared with right cathodal/left cathodal and sham stimulation. These results suggest not only the causal involvement of the DLPFC in driving, but also right hemisphere dominance for vehicle control. The findings of this study indicate that tDCS can be a useful tool to examine the causal role of a specific brain region in ecologically valid environments, and also might be a help to drivers with difficulties in vehicle control. Copyright © 2014 Elsevier B.V. All rights reserved.

Polarity-dependent effects of transcranial direct current stimulation in obsessive-compulsive disorder.

PubMed

D'Urso, Giordano; Brunoni, Andre Russowsky; Anastasia, Annalisa; Micillo, Marco; de Bartolomeis, Andrea; Mantovani, Antonio

2016-01-01

About one third of patients with obsessive-compulsive disorder (OCD) fail to experience significant clinical benefit from currently available treatments. Hyperactivity of the presupplementary motor area (pre-SMA) has been detected in OCD patients, but it is not clear whether it is the primary cause or a secondary compensatory mechanism in OCD pathophysiology. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique with polarity-dependent effects on motor cortical excitability. A 33-year-old woman with treatment-resistant OCD received 20 daily consecutive 2 mA/20 min tDCS sessions with the active electrode placed on the pre-SMA, according to the 10-20 EEG system, and the reference electrode on the right deltoid. The first 10 sessions were anodal, while the last 10 were cathodal. Symptoms severity was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) severity score. In the end of anodal stimulation, OCD symptoms had worsened. Subsequent cathodal stimulation induced a dramatic clinical improvement, which led to an overall 30% reduction in baseline symptoms severity score on the Y-BOCS. Our study supports the hypothesis that pre-SMA hyperfunction might be responsible for OCD symptoms and shows that cathodal inhibitory tDCS over this area might be an option when dealing with treatment-resistant OCD.

Modulation of motor performance and motor learning by transcranial direct current stimulation.

PubMed

Reis, Janine; Fritsch, Brita

2011-12-01

Transcranial direct current stimulation (tDCS) has shown preliminary success in improving motor performance and motor learning in healthy individuals, and restitution of motor deficits in stroke patients. This brief review highlights some recent work. Within the past years, behavioural studies have confirmed and specified the timing and polarity specific effects of tDCS on motor skill learning and motor adaptation. There is strong evidence that timely co-application of (hand/arm) training and anodal tDCS to the contralateral M1 can improve motor learning. Improvements in motor function as measured by clinical scores have been described for combined tDCS and training in stroke patients. For this purpose, electrode montages have been modified with respect to interhemispheric imbalance after brain injury. Cathodal tDCS applied to the unlesioned M1 or bihemispheric M1 stimulation appears to be well tolerated and useful to induce improvements in motor function. Mechanistic studies in humans and animals are discussed with regard to physiological motor learning. tDCS is well tolerated, easy to use and capable of inducing lasting improvements in motor function. This method holds promise for the rehabilitation of motor disabilities, although acute studies in patients with brain injury are so far lacking.

Transcranial Direct Current Stimulation in Stroke Rehabilitation: A Review of Recent Advancements

PubMed Central

Gomez Palacio Schjetnan, Andrea; Faraji, Jamshid; Metz, Gerlinde A.; Tatsuno, Masami; Luczak, Artur

2013-01-01

Transcranial direct current stimulation (tDCS) is a promising technique to treat a wide range of neurological conditions including stroke. The pathological processes following stroke may provide an exemplary system to investigate how tDCS promotes neuronal plasticity and functional recovery. Changes in synaptic function after stroke, such as reduced excitability, formation of aberrant connections, and deregulated plastic modifications, have been postulated to impede recovery from stroke. However, if tDCS could counteract these negative changes by influencing the system's neurophysiology, it would contribute to the formation of functionally meaningful connections and the maintenance of existing pathways. This paper is aimed at providing a review of underlying mechanisms of tDCS and its application to stroke. In addition, to maximize the effectiveness of tDCS in stroke rehabilitation, future research needs to determine the optimal stimulation protocols and parameters. We discuss how stimulation parameters could be optimized based on electrophysiological activity. In particular, we propose that cortical synchrony may represent a biomarker of tDCS efficacy to indicate communication between affected areas. Understanding the mechanisms by which tDCS affects the neural substrate after stroke and finding ways to optimize tDCS for each patient are key to effective rehabilitation approaches. PMID:23533955

Optimization of focality and direction in dense electrode array transcranial direct current stimulation (tDCS)

NASA Astrophysics Data System (ADS)

Guler, Seyhmus; Dannhauer, Moritz; Erem, Burak; Macleod, Rob; Tucker, Don; Turovets, Sergei; Luu, Phan; Erdogmus, Deniz; Brooks, Dana H.

2016-06-01

Objective. Transcranial direct current stimulation (tDCS) aims to alter brain function non-invasively via electrodes placed on the scalp. Conventional tDCS uses two relatively large patch electrodes to deliver electrical current to the brain region of interest (ROI). Recent studies have shown that using dense arrays containing up to 512 smaller electrodes may increase the precision of targeting ROIs. However, this creates a need for methods to determine effective and safe stimulus patterns as the number of degrees of freedom is much higher with such arrays. Several approaches to this problem have appeared in the literature. In this paper, we describe a new method for calculating optimal electrode stimulus patterns for targeted and directional modulation in dense array tDCS which differs in some important aspects with methods reported to date. Approach. We optimize stimulus pattern of dense arrays with fixed electrode placement to maximize the current density in a particular direction in the ROI. We impose a flexible set of safety constraints on the current power in the brain, individual electrode currents, and total injected current, to protect subject safety. The proposed optimization problem is convex and thus efficiently solved using existing optimization software to find unique and globally optimal electrode stimulus patterns. Main results. Solutions for four anatomical ROIs based on a realistic head model are shown as exemplary results. To illustrate the differences between our approach and previously introduced methods, we compare our method with two of the other leading methods in the literature. We also report on extensive simulations that show the effect of the values chosen for each proposed safety constraint bound on the optimized stimulus patterns. Significance. The proposed optimization approach employs volume based ROIs, easily adapts to different sets of safety constraints, and takes negligible time to compute. An in-depth comparison study gives

Modulation of Brain Activity with Noninvasive Transcranial Direct Current Stimulation (tDCS): Clinical Applications and Safety Concerns

PubMed Central

Zhao, Haichao; Qiao, Lei; Fan, Dongqiong; Zhang, Shuyue; Turel, Ofir; Li, Yonghui; Li, Jun; Xue, Gui; Chen, Antao; He, Qinghua

2017-01-01

Transcranial direct current stimulation (tDCS) is a widely-used tool to induce neuroplasticity and modulate cortical function by applying weak direct current over the scalp. In this review, we first introduce the underlying mechanism of action, the brief history from discovery to clinical scientific research, electrode positioning and montages, and parameter setup of tDCS. Then, we review tDCS application in clinical samples including people with drug addiction, major depression disorder, Alzheimer's disease, as well as in children. This review covers the typical characteristics and the underlying neural mechanisms of tDCS treatment in such studies. This is followed by a discussion of safety, especially when the current intensity is increased or the stimulation duration is prolonged. Given such concerns, we provide detailed suggestions regarding safety procedures for tDCS operation. Lastly, future research directions are discussed. They include foci on the development of multi-tech combination with tDCS such as with TMS and fMRI; long-term behavioral and morphological changes; possible applications in other research domains, and more animal research to deepen the understanding of the biological and physiological mechanisms of tDCS stimulation. PMID:28539894

Combined motor point associative stimulation (MPAS) and transcranial direct current stimulation (tDCS) improves plateaued manual dexterity performance.

PubMed

Hoseini, Najmeh; Munoz-Rubke, Felipe; Wan, Hsuan-Yu; Block, Hannah J

2016-10-28

Motor point associative stimulation (MPAS) in hand muscles is known to modify motor cortex excitability and improve learning rate, but not plateau of performance, in manual dexterity tasks. Central stimulation of motor cortex, such as transcranial direct current stimulation (tDCS), can have similar effects if accompanied by motor practice, which can be difficult and tiring for patients. Here we asked whether adding tDCS to MPAS could improve manual dexterity in healthy individuals who are already performing at their plateau, with no motor practice during stimulation. We hypothesized that MPAS could provide enough coordinated muscle activity to make motor practice unnecessary, and that this combination of stimulation techniques could yield improvements even in subjects at or near their peak. If so, this approach could have a substantial effect on patients with impaired dexterity, who are far from their peak. MPAS was applied for 30min to two right hand muscles important for manual dexterity. tDCS was simultaneously applied over left sensorimotor cortex. The motor cortex input/output (I/O) curve was assessed with transcranial magnetic stimulation (TMS), and manual dexterity was assessed with the Purdue Pegboard Test. Compared to sham or cathodal tDCS combined with MPAS, anodal tDCS combined with MPAS significantly increased the plateau of manual dexterity. This result suggests that MPAS has the potential to substitute for motor practice in mediating a beneficial effect of tDCS on manual dexterity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Simultaneous transcranial direct current stimulation (tDCS) and whole-head magnetoencephalography (MEG): assessing the impact of tDCS on slow cortical magnetic fields.

PubMed

Garcia-Cossio, Eliana; Witkowski, Matthias; Robinson, Stephen E; Cohen, Leonardo G; Birbaumer, Niels; Soekadar, Surjo R

2016-10-15

Transcranial direct current stimulation (tDCS) can influence cognitive, affective or motor brain functions. Whereas previous imaging studies demonstrated widespread tDCS effects on brain metabolism, direct impact of tDCS on electric or magnetic source activity in task-related brain areas could not be confirmed due to the difficulty to record such activity simultaneously during tDCS. The aim of this proof-of-principal study was to demonstrate the feasibility of whole-head source localization and reconstruction of neuromagnetic brain activity during tDCS and to confirm the direct effect of tDCS on ongoing neuromagnetic activity in task-related brain areas. Here we show for the first time that tDCS has an immediate impact on slow cortical magnetic fields (SCF, 0-4Hz) of task-related areas that are identical with brain regions previously described in metabolic neuroimaging studies. 14 healthy volunteers performed a choice reaction time (RT) task while whole-head magnetoencephalography (MEG) was recorded. Task-related source-activity of SCFs was calculated using synthetic aperture magnetometry (SAM) in absence of stimulation and while anodal, cathodal or sham tDCS was delivered over the right primary motor cortex (M1). Source reconstruction revealed task-related SCF modulations in brain regions that precisely matched prior metabolic neuroimaging studies. Anodal and cathodal tDCS had a polarity-dependent impact on RT and SCF in primary sensorimotor and medial centro-parietal cortices. Combining tDCS and whole-head MEG is a powerful approach to investigate the direct effects of transcranial electric currents on ongoing neuromagnetic source activity, brain function and behavior. Copyright © 2015 Elsevier Inc. All rights reserved.

Simultaneous transcranial direct current stimulation (tDCS) and whole-head magnetoencephalography (MEG): assessing the impact of tDCS on slow cortical magnetic fields

PubMed Central

Garcia-Cossio, Eliana; Witkowski, Matthias; Robinson, Stephen E.; Cohen, Leonardo G.; Birbaumer, Niels; Soekadar, Surjo R.

2016-01-01

Transcranial direct current stimulation (tDCS) can influence cognitive, affective or motor brain functions. Whereas previous imaging studies demonstrated widespread tDCS effects on brain metabolism, direct impact of tDCS on electric or magnetic source activity in task-related brain areas could not be confirmed due to the difficulty to record such activity simultaneously during tDCS. The aim of this proof-of-principal study was to demonstrate the feasibility of whole-head source localization and reconstruction of neuromagnetic brain activity during tDCS and to confirm the direct effect of tDCS on ongoing neuromagnetic activity in task-related brain areas. Here we show for the first time that tDCS has an immediate impact on slow cortical magnetic fields (SCF, 0–4 Hz) of task-related areas that are identical with brain regions previously described in metabolic neuroimaging studies. 14 healthy volunteers performed a choice reaction time (RT) task while whole-head magnetoencephalography (MEG) was recorded. Task-related source-activity of SCFs was calculated using synthetic aperture magnetometry (SAM) in absence of stimulation and while anodal, cathodal or sham tDCS was delivered over the right primary motor cortex (M1). Source reconstruction revealed task-related SCF modulations in brain regions that precisely matched prior metabolic neuroimaging studies. Anodal and cathodal tDCS had a polarity-dependent impact on RT and SCF in primary sensorimotor and medial centro-parietal cortices. Combining tDCS and whole-head MEG is a powerful approach to investigate the direct effects of transcranial electric currents on ongoing neuromagnetic source activity, brain function and behavior. PMID:26455796

MRI-based noninvasive measurement of intracranial compliance derived from the relationship between transcranial blood and cerebrospinal fluid flows: modeling vs. direct approach

NASA Astrophysics Data System (ADS)

Tain, Rong-Wen; Alperin, Noam

2008-03-01

Intracranial compliance (ICC) determines the ability of the intracranial space to accommodate increase in volume (e.g., brain swelling) without a large increase in intracranial pressure (ICP). Therefore, measurement of ICC is potentially important for diagnosis and guiding treatment of related neurological problems. Modeling based approach uses an assumed lumped-parameter model of the craniospinal system (CSS) (e.g., RCL circuit), with either the arterial or the net transcranial blood flow (arterial inflow minus venous outflow) as input and the cranio-spinal cerebrospinal fluid (CSF) flow as output. The phase difference between the output and input is then often used as a measure of ICC However, it is not clear whether there is a predetermined relationship between ICC and the phase difference between these waveforms. A different approach for estimation of ICC has been recently proposed. This approach estimates ICC from the ratio of the intracranial volume and pressure changes that occur naturally with each heartbeat. The current study evaluates the sensitivity of the phase-based and the direct approach to changes in ICC. An RLC circuit model of the cranio-spinal system is used to simulate the cranio-spinal CSF flow for 3 different ICC states using the transcranial blood flows measured by MRI phase contrast from healthy human subjects. The effect of the increase in the ICC on the magnitude and phase response is calculated from the system's transfer function. We observed that within the heart rate frequency range, changes in ICC predominantly affected the amplitude of CSF pulsation and less so the phases. The compliance is then obtained for the different ICC states using the direct approach. The measures of compliance calculated using the direct approach demonstrated the highest sensitivity for changes in ICC. This work explains why phase shift based measure of ICC is less sensitive than amplitude based measures such as the direct approach method.

Repetitive transcranial magnetic stimulation improves consciousness disturbance in stroke patients: A quantitative electroencephalography spectral power analysis.

PubMed

Xie, Ying; Zhang, Tong

2012-11-05

Repetitive transcranial magnetic stimulation is a noninvasive treatment technique that can directly alter cortical excitability and improve cerebral functional activity in unconscious patients. To investigate the effects and the electrophysiological changes of repetitive transcranial magnetic stimulation cortical treatment, 10 stroke patients with non-severe brainstem lesions and with disturbance of consciousness were treated with repetitive transcranial magnetic stimulation. A quantitative electroencephalography spectral power analysis was also performed. The absolute power in the alpha band was increased immediately after the first repetitive transcranial magnetic stimulation treatment, and the energy was reduced in the delta band. The alpha band relative power values slightly decreased at 1 day post-treatment, then increased and reached a stable level at 2 weeks post-treatment. Glasgow Coma Score and JFK Coma Recovery Scale-Revised score were improved. Relative power value in the alpha band was positively related to Glasgow Coma Score and JFK Coma Recovery Scale-Revised score. These data suggest that repetitive transcranial magnetic stimulation is a noninvasive, safe, and effective treatment technology for improving brain functional activity and promoting awakening in unconscious stroke patients.

Improving Interference Control in ADHD Patients with Transcranial Direct Current Stimulation (tDCS).

PubMed

Breitling, Carolin; Zaehle, Tino; Dannhauer, Moritz; Bonath, Björn; Tegelbeckers, Jana; Flechtner, Hans-Henning; Krauel, Kerstin

2016-01-01

The use of transcranial direct current stimulation (tDCS) in patients with attention deficit hyperactivity disorder (ADHD) has been suggested as a promising alternative to psychopharmacological treatment approaches due to its local and network effects on brain activation. In the current study, we investigated the impact of tDCS over the right inferior frontal gyrus (rIFG) on interference control in 21 male adolescents with ADHD and 21 age matched healthy controls aged 13-17 years, who underwent three separate sessions of tDCS (anodal, cathodal, and sham) while completing a Flanker task. Even though anodal stimulation appeared to diminish commission errors in the ADHD group, the overall analysis revealed no significant effect of tDCS. Since participants showed a considerable learning effect from the first to the second session, performance in the first session was separately analyzed. ADHD patients receiving sham stimulation in the first session showed impaired interference control compared to healthy control participants whereas ADHD patients who were exposed to anodal stimulation, showed comparable performance levels (commission errors, reaction time variability) to the control group. These results suggest that anodal tDCS of the right inferior frontal gyrus could improve interference control in patients with ADHD.

Facilitation of Function and Manipulation Knowledge of Tools Using Transcranial Direct Current Stimulation (tDCS).

PubMed

Ishibashi, Ryo; Mima, Tatsuya; Fukuyama, Hidenao; Pobric, Gorana

2017-01-01

Using a variety of tools is a common and essential component of modern human life. Patients with brain damage or neurological disorders frequently have cognitive deficits in their recognition and manipulation of tools. In this study, we focused on improving tool-related cognition using transcranial direct current stimulation (tDCS). Converging evidence from neuropsychology, neuroimaging and non- invasive brain stimulation has identified the anterior temporal lobe (ATL) and inferior parietal lobule (IPL) as brain regions supporting action semantics. We observed enhanced performance in tool cognition with anodal tDCS over ATL and IPL in two cognitive tasks that require rapid access to semantic knowledge about the function or manipulation of common tools. ATL stimulation improved access to both function and manipulation knowledge of tools. The effect of IPL stimulation showed a trend toward better manipulation judgments. Our findings support previous studies of tool semantics and provide a novel approach for manipulation of underlying circuits.

Transcranial direct current stimulation and power spectral parameters: a tDCS/EEG co-registration study

PubMed Central

Mangia, Anna L.; Pirini, Marco; Cappello, Angelo

2014-01-01

Transcranial direct current stimulation (tDCS) delivers low electric currents to the brain through the scalp. Constant electric currents induce shifts in neuronal membrane excitability, resulting in secondary changes in cortical activity. Concomitant electroencephalography (EEG) monitoring during tDCS can provide valuable information on the tDCS mechanisms of action. This study examined the effects of anodal tDCS on spontaneous cortical activity in a resting brain to disclose possible modulation of spontaneous oscillatory brain activity. EEG activity was measured in ten healthy subjects during and after a session of anodal stimulation of the postero-parietal cortex to detect the tDCS-induced alterations. Changes in the theta, alpha, beta, and gamma power bands were investigated. Three main findings emerged: (1) an increase in theta band activity during the first minutes of stimulation; (2) an increase in alpha and beta power during and after stimulation; (3) a widespread activation in several brain regions. PMID:25147519

Both anodal and cathodal transcranial direct current stimulation improves semantic processing.

PubMed

Brückner, Sabrina; Kammer, Thomas

2017-02-20

Transcranial direct current stimulation (tDCS) is a common method to modulate cortical activity. Anodal tDCS is usually associated with an enhancement of the stimulated brain area, whereas cathodal tDCS is often described as inhibitory brain stimulation method. Our aim was to investigate whether this canonical assumption derived from the motor system could be transferred to the semantic system. Three groups with 20 healthy subjects each were stimulated at Wernicke's area with either anodal, cathodal or sham tDCS. Subsequently, they performed a simple lexical decision task for a duration of about 25min. Subjects receiving anodal tDCS revealed faster reaction times (RTs) compared to the sham group, although not reaching statistical significance. Surprisingly, in the cathodal group RTs were decreased significantly. All subjects were faster in the second half of the task, but the tDCS-induced improvement lasted for the entire duration of the task. Error rates were not influenced by tDCS, neither were RTs in a choice reaction time task. Thus, both anodal and cathodal tDCS applied to Wernicke's area improved semantic processing. Recently, a meta-analysis revealed that the canonical anodal excitation and cathodal inhibition assumption is observed rarely in cognitive studies. In particular, an inhibitory effect of cathodal tDCS on cognition is rare. Our findings thus support the speculation, that especially language functions could be somewhat 'immune' to cathodal inhibition. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Transcranial direct-current stimulation modulates offline visual oscillatory activity: A magnetoencephalography study

PubMed Central

Heinrichs-Graham, Elizabeth; McDermott, Timothy J.; Mills, Mackenzie S.; Coolidge, Nathan M.; Wilson, Tony W.

2017-01-01

Transcranial direct-current stimulation (tDCS) is a noninvasive neuromodulatory method that involves delivering low amplitude, direct current to specific regions of the brain. While a wealth of literature shows changes in behavior and cognition following tDCS administration, the underlying neuronal mechanisms remain largely unknown. Neuroimaging studies have generally used fMRI and shown only limited consensus to date, while the few electrophysiological studies have reported mostly null or counterintuitive findings. The goal of the current investigation was to quantify tDCS-induced alterations in the oscillatory dynamics of visual processing. To this end, we performed either active or sham tDCS using an occipital-frontal electrode configuration, and then recorded magnetoencephalography (MEG) offline during a visual entrainment task. Significant oscillatory responses were imaged in the time-frequency domain using beamforming, and the effects of tDCS on absolute and relative power were assessed. The results indicated significantly increased basal alpha levels in the occipital cortex following anodal tDCS, as well as reduced occipital synchronization at the second harmonic of the stimulus-flicker frequency relative to sham stimulation. In addition, we found reduced power in brain regions near the cathode (e.g., right inferior frontal gyrus) following active tDCS, which was absent in the sham group. Taken together, these results suggest that anodal tDCS of the occipital cortices differentially modulates spontaneous and induced activity, and may interfere with the entrainment of neuronal populations by a visual-flicker stimulus. These findings also demonstrate the importance of electrode configuration on whole-brain dynamics, and highlight the deceptively complicated nature of tDCS in the context of neurophysiology. PMID:28042984

Spatial and polarity precision of concentric high-definition transcranial direct current stimulation (HD-tDCS)

NASA Astrophysics Data System (ADS)

Alam, Mahtab; Truong, Dennis Q.; Khadka, Niranjan; Bikson, Marom

2016-06-01

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that applies low amplitude current via electrodes placed on the scalp. Rather than directly eliciting a neuronal response, tDCS is believed to modulate excitability—enhancing or suppressing neuronal activity in regions of the brain depending on the polarity of stimulation. The specificity of tDCS to any therapeutic application derives in part from how electrode configuration determines the brain regions that are stimulated. Conventional tDCS uses two relatively large pads (>25 cm2) whereas high-definition tDCS (HD-tDCS) uses arrays of smaller electrodes to enhance brain targeting. The 4  ×  1 concentric ring HD-tDCS (one center electrode surrounded by four returns) has been explored in application where focal targeting of cortex is desired. Here, we considered optimization of concentric ring HD-tDCS for targeting: the role of electrodes in the ring and the ring’s diameter. Finite element models predicted cortical electric field generated during tDCS. High resolution MRIs were segmented into seven tissue/material masks of varying conductivities. Computer aided design (CAD) model of electrodes, gel, and sponge pads were incorporated into the segmentation. Volume meshes were generated and the Laplace equation (\

A pilot study of the tolerability and effects of high-definition transcranial direct current stimulation (HD-tDCS) on pain perception.

PubMed

Borckardt, Jeffrey J; Bikson, Marom; Frohman, Heather; Reeves, Scott T; Datta, Abhishek; Bansal, Varun; Madan, Alok; Barth, Kelly; George, Mark S

2012-02-01

Several brain stimulation technologies are beginning to evidence promise as pain treatments. However, traditional versions of 1 specific technique, transcranial direct current stimulation (tDCS), stimulate broad regions of cortex with poor spatial precision. A new tDCS design, called high definition tDCS (HD-tDCS), allows for focal delivery of the charge to discrete regions of the cortex. We sought to preliminarily test the safety and tolerability of the HD-tDCS technique as well as to evaluate whether HD-tDCS over the motor cortex would decrease pain and sensory experience. Twenty-four healthy adult volunteers underwent quantitative sensory testing before and after 20 minutes of real (n = 13) or sham (n = 11) 2 mA HD-tDCS over the motor cortex. No adverse events occurred and no side effects were reported. Real HD-tDCS was associated with significantly decreased heat and cold sensory thresholds, decreased thermal wind-up pain, and a marginal analgesic effect for cold pain thresholds. No significant effects were observed for mechanical pain thresholds or heat pain thresholds. HD-tDCS appears well tolerated, and produced changes in underlying cortex that are associated with changes in pain perception. Future studies are warranted to investigate HD-tDCS in other applications, and to examine further its potential to affect pain perception. This article presents preliminary tolerability and efficacy data for a new focal brain stimulation technique called high definition transcranial direct current stimulation. This technique may have applications in the management of pain. Copyright © 2012. Published by Elsevier Inc.

Determinants of the electric field during transcranial direct current stimulation.

PubMed

Opitz, Alexander; Paulus, Walter; Will, Susanne; Antunes, Andre; Thielscher, Axel

2015-04-01

Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field distribution in the brain during tDCS. We constructed anatomically realistic finite element (FEM) models of two individual heads including conductivity anisotropy and different skull layers. We simulated a widely employed electrode montage to induce motor cortex plasticity and moved the stimulating electrode over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect is counteracted by a larger proportion of higher conducting spongy bone in thicker regions leading to a more homogenous current over the skull. Using a multiple regression model we could identify key factors that determine the field distribution to a significant extent, namely the thicknesses of the cerebrospinal fluid and the skull, the gyral depth and the distance to the anode and cathode. These factors account for up to 50% of the spatial variation of the electric field strength. Further, we demonstrate that individual anatomical factors can lead to stimulation "hotspots" which are partly resistant to electrode positioning. Our results give valuable novel insights in the biophysical foundation of tDCS and highlight the importance to account for individual anatomical factors when choosing an electrode montage. Copyright © 2015 Elsevier Inc. All rights reserved.

Transcranial Direct Current Stimulation Post-Stroke Upper Extremity Motor Recovery Studies Exhibit a Dose–Response Relationship

PubMed Central

Chhatbar, Pratik Y.; Ramakrishnan, Viswanathan; Kautz, Steven; George, Mark S.; Adams, Robert J.; Feng, Wuwei

2015-01-01

Background and purpose Transcranial direct current stimulation (tDCS) has shown mixed results in post-stroke motor recovery, possibly because of tDCS dose differences. The purpose of this meta-analysis was to explore whether the outcome has a dose–response relationship with various dose-related parameters. Methods The literature was searched for double-blind, randomized, sham-controlled clinical trials investigating the role of tDCS (≥5 sessions) in post-stroke motor recovery as measured by the Fugl-Meyer Upper Extremity (FM-UE) scale. Improvements in FM-UE scores were compared between active and sham groups by calculating standardized mean differences (Hedge’s g) to derive a summary effect size. Inverse-variance-weighted linear meta-regression across individual studies was performed between various tDCS parameters and Hedge’s g to test for dose–response relationships. Results Eight studies with total of 213 stroke subjects were included. Summary Hedge’s g was statistically significant in favor of the active group (Hedge’s g = 0.61, p = 0.02) suggesting moderate effect. Specifically, studies that used bihemispheric tDCS montage (Hedge’s g = 1.30, p = 0.08) or that recruited chronic stroke patients (Hedge’s g = 1.23, p = 0.02) showed large improvements in the active group. A positive dose–response relationship was found with current density (p = 0.017) and charge density (p = 0.004), but not with current amplitude. Moreover, a negative dose–response relationship was found with electrode size (p < 0.001, smaller electrodes were more effective). Conclusions Our meta-analysis and meta-regression results suggest superior motor recovery in the active group when compared to the sham group and dose–response relationships relating to electrode size, charge density and current density. These results need to be confirmed in future dedicated studies. PMID:26433609

A Randomized, Double-Blind, Sham-Controlled Trial of Transcranial Direct Current Stimulation in Attention-Deficit/Hyperactivity Disorder

PubMed Central

Cosmo, Camila; Baptista, Abrahão Fontes; de Araújo, Arão Nogueira; do Rosário, Raphael Silva; Miranda, José Garcia Vivas; Montoya, Pedro; de Sena, Eduardo Pondé

2015-01-01

Background Current standardized treatments for cognitive impairment in attention-deficit/hyperactivity disorder remain limited and their efficacy restricted. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in several neuropsychiatric disorders. Nevertheless, the effects of tDCS in reducing cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD) have not yet been investigated. Methods A parallel, randomized, double-blind, sham-controlled trial was conducted to examine the efficacy of tDCS on the modulation of inhibitory control in adults with ADHD. Thirty patients were randomly allocated to each group and performed a go/no-go task before and after a single session of either anodal stimulation (1 mA) over the left dorsolateral prefrontal cortex or sham stimulation. Results A nonparametric two-sample Wilcoxon rank-sum (Mann-Whitney) test revealed no significant differences between the two groups of individuals with ADHD (tDCS vs. sham) in regard to behavioral performance in the go/no go tasks. Furthermore, the effect sizes of group differences after treatment for the primary outcome measures—correct responses, impulsivity and omission errors—were small. No adverse events resulting from stimulation were reported. Conclusion According to these findings, there is no evidence in support of the use of anodal stimulation over the left dorsolateral prefrontal cortex as an approach for improving inhibitory control in ADHD patients. To the best of our knowledge, this is the first clinical study to assess the cognitive effects of tDCS in individuals with ADHD. Further research is needed to assess the clinical efficacy of tDCS in this population. Trial Registration ClinicalTrials.gov NCT01968512 PMID:26267861

Modulation of Total Sleep Time by Transcranial Direct Current Stimulation (tDCS).

PubMed

Frase, Lukas; Piosczyk, Hannah; Zittel, Sulamith; Jahn, Friederike; Selhausen, Peter; Krone, Lukas; Feige, Bernd; Mainberger, Florian; Maier, Jonathan G; Kuhn, Marion; Klöppel, Stefan; Normann, Claus; Sterr, Annette; Spiegelhalder, Kai; Riemann, Dieter; Nitsche, Michael A; Nissen, Christoph

2016-09-01

Arousal and sleep are fundamental physiological processes, and their modulation is of high clinical significance. This study tested the hypothesis that total sleep time (TST) in humans can be modulated by the non-invasive brain stimulation technique transcranial direct current stimulation (tDCS) targeting a 'top-down' cortico-thalamic pathway of sleep-wake regulation. Nineteen healthy participants underwent a within-subject, repeated-measures protocol across five nights in the sleep laboratory with polysomnographic monitoring (adaptation, baseline, three experimental nights). tDCS was delivered via bi-frontal target electrodes and bi-parietal return electrodes before sleep (anodal 'activation', cathodal 'deactivation', and sham stimulation). Bi-frontal anodal stimulation significantly decreased TST, compared with cathodal and sham stimulation. This effect was location specific. Bi-frontal cathodal stimulation did not significantly increase TST, potentially due to ceiling effects in good sleepers. Exploratory resting-state EEG analyses before and after the tDCS protocols were consistent with the notion of increased cortical arousal after anodal stimulation and decreased cortical arousal after cathodal stimulation. The study provides proof-of-concept that TST can be decreased by non-invasive bi-frontal anodal tDCS in healthy humans. Further elucidating the 'top-down' pathway of sleep-wake regulation is expected to increase knowledge on the fundamentals of sleep-wake regulation and to contribute to the development of novel treatments for clinical conditions of disturbed arousal and sleep.

Transcranial direct current stimulation over prefrontal cortex diminishes degree of risk aversion.

PubMed

Ye, Hang; Chen, Shu; Huang, Daqiang; Wang, Siqi; Jia, Yongmin; Luo, Jun

2015-06-26

Previous studies have established that transcranial direct current stimulation (tDCS) is a powerful technique for manipulating the activity of the human cerebral cortex. Many studies have found that weighing the risks and benefits in decision-making involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC). We studied whether participants change the balance of risky and safe responses after receiving tDCS applied over the right and left prefrontal cortex. A total of 60 healthy volunteers performed a risk task while they received either anodal tDCS over the right prefrontal cortex, with cathodal over the left; anodal tDCS over the left prefrontal cortex, with cathodal over the right; or sham stimulation. The participants tended to choose less risky options after receiving sham stimulation, demonstrating that the task might be highly influenced by the "wealth effect". There was no statistically significant change after either right anodal/left cathodal or left anodal/right cathodal tDCS, indicating that both types of tDCS impact the participants' degrees of risk aversion, and therefore, counteract the wealth effect. We also found gender differences in the participants' choices. These findings extend the notion that DLPFC activity is critical for risk decision-making. Application of tDCS to the right/left DLPFC may impact a person's attitude to taking risks. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Transcranial direct current stimulation in obsessive-compulsive disorder: emerging clinical evidence and considerations for optimal montage of electrodes.

PubMed

Senço, Natasha M; Huang, Yu; D'Urso, Giordano; Parra, Lucas C; Bikson, Marom; Mantovani, Antonio; Shavitt, Roseli G; Hoexter, Marcelo Q; Miguel, Eurípedes C; Brunoni, André R

2015-07-01

Neuromodulation techniques for obsessive-compulsive disorder (OCD) treatment have expanded with greater understanding of the brain circuits involved. Transcranial direct current stimulation (tDCS) might be a potential new treatment for OCD, although the optimal montage is unclear. To perform a systematic review on meta-analyses of repetitive transcranianal magnetic stimulation (rTMS) and deep brain stimulation (DBS) trials for OCD, aiming to identify brain stimulation targets for future tDCS trials and to support the empirical evidence with computer head modeling analysis. Systematic reviews of rTMS and DBS trials on OCD in Pubmed/MEDLINE were searched. For the tDCS computational analysis, we employed head models with the goal of optimally targeting current delivery to structures of interest. Only three references matched our eligibility criteria. We simulated four different electrodes montages and analyzed current direction and intensity. Although DBS, rTMS and tDCS are not directly comparable and our theoretical model, based on DBS and rTMS targets, needs empirical validation, we found that the tDCS montage with the cathode over the pre-supplementary motor area and extra-cephalic anode seems to activate most of the areas related to OCD.

Enhancement of Cortical Excitability and Lower Limb Motor Function in Patients With Stroke by Transcranial Direct Current Stimulation.

PubMed

Chang, Min Cheol; Kim, Dae Yul; Park, Dae Hwan

2015-01-01

Motor dysfunction in the lower limbs is a common sequela in stroke patients. We used transcranial magnetic stimulation (TMS) to determine if applying transcranial direct current stimulation (tDCS) to the primary motor cortex helps enhance cortical excitability. Furthermore, we evaluate if combination anodal tDCS and conventional physical therapy improves motor function in the lower limbs. Twenty-four patients with early-stage stroke were randomly assigned to 2 groups: 1) the tDCS group, in which patients received 10 sessions of anodal tDCS and conventional physical therapy; and 2) the sham group, in which patients received 10 sessions of sham stimulation and conventional physical therapy. One day before and after intervention, the motor-evoked potential (MEP) of the affected tibialis anterior muscle was evaluated and motor function was assessed using the lower limb subscale of the Fugl-Meyer Assessment (FMA-LE), lower limb Motricity Index (MI-LE), Functional Ambulatory Category (FAC), Berg Balance Scale (BBS), and gait analysis. The MEPs in the tDCS group became shorter in latency and higher in amplitude after intervention in comparison with the sham group. Improvements in FMA-LE and MI-LE were greater in the tDCS group, but no significant differences in FAC or BBS scores were found. Also, the changes observed on the gait analyses did not significantly differ between the tDCS and sham groups. Combination anodal tDCS and conservative physical therapy appears to be a beneficial therapeutic modality for improving motor function in the lower limbs in patients with subacute stroke. Copyright © 2015 Elsevier Inc. All rights reserved.

Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia.

PubMed

Bradnam, Lynley V; Graetz, Lynton J; McDonnell, Michelle N; Ridding, Michael C

2015-01-01

There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer's dystonia, 3 musician's dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer's Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia.

Use of transcranial direct current stimulation for the treatment of auditory hallucinations of schizophrenia – a systematic review

PubMed Central

Pondé, Pedro H; de Sena, Eduardo P; Camprodon, Joan A; de Araújo, Arão Nogueira; Neto, Mário F; DiBiasi, Melany; Baptista, Abrahão Fontes; Moura, Lidia MVR; Cosmo, Camila

2017-01-01

Introduction Auditory hallucinations are defined as experiences of auditory perceptions in the absence of a provoking external stimulus. They are the most prevalent symptoms of schizophrenia with high capacity for chronicity and refractoriness during the course of disease. The transcranial direct current stimulation (tDCS) – a safe, portable, and inexpensive neuromodulation technique – has emerged as a promising treatment for the management of auditory hallucinations. Objective The aim of this study is to analyze the level of evidence in the literature available for the use of tDCS as a treatment for auditory hallucinations in schizophrenia. Methods A systematic review was performed, searching in the main electronic databases including the Cochrane Library and MEDLINE/PubMed. The searches were performed by combining descriptors, applying terms of the Medical Subject Headings (MeSH) of Descriptors of Health Sciences and descriptors contractions. PRISMA protocol was used as a guide and the terms used were the clinical outcomes (“Schizophrenia” OR “Auditory Hallucinations” OR “Auditory Verbal Hallucinations” OR “Psychosis”) searched together (“AND”) with interventions (“transcranial Direct Current Stimulation” OR “tDCS” OR “Brain Polarization”). Results Six randomized controlled trials that evaluated the effects of tDCS on the severity of auditory hallucinations in schizophrenic patients were selected. Analysis of the clinical results of these studies pointed toward incongruence in the information with regard to the therapeutic use of tDCS with a view to reducing the severity of auditory hallucinations in schizophrenia. Only three studies revealed a therapeutic benefit, manifested by reductions in severity and frequency of auditory verbal hallucinations in schizophrenic patients. Conclusion Although tDCS has shown promising results in reducing the severity of auditory hallucinations in schizophrenic patients, this technique cannot

Improving Interference Control in ADHD Patients with Transcranial Direct Current Stimulation (tDCS)

PubMed Central

Breitling, Carolin; Zaehle, Tino; Dannhauer, Moritz; Bonath, Björn; Tegelbeckers, Jana; Flechtner, Hans-Henning; Krauel, Kerstin

2016-01-01

The use of transcranial direct current stimulation (tDCS) in patients with attention deficit hyperactivity disorder (ADHD) has been suggested as a promising alternative to psychopharmacological treatment approaches due to its local and network effects on brain activation. In the current study, we investigated the impact of tDCS over the right inferior frontal gyrus (rIFG) on interference control in 21 male adolescents with ADHD and 21 age matched healthy controls aged 13–17 years, who underwent three separate sessions of tDCS (anodal, cathodal, and sham) while completing a Flanker task. Even though anodal stimulation appeared to diminish commission errors in the ADHD group, the overall analysis revealed no significant effect of tDCS. Since participants showed a considerable learning effect from the first to the second session, performance in the first session was separately analyzed. ADHD patients receiving sham stimulation in the first session showed impaired interference control compared to healthy control participants whereas ADHD patients who were exposed to anodal stimulation, showed comparable performance levels (commission errors, reaction time variability) to the control group. These results suggest that anodal tDCS of the right inferior frontal gyrus could improve interference control in patients with ADHD. PMID:27147964

Transcranial direct current stimulation transiently increases the blood-brain barrier solute permeability in vivo

NASA Astrophysics Data System (ADS)

Shin, Da Wi; Khadka, Niranjan; Fan, Jie; Bikson, Marom; Fu, Bingmei M.

2016-03-01

Transcranial Direct Current Stimulation (tDCS) is a non-invasive electrical stimulation technique investigated for a broad range of medical and performance indications. Whereas prior studies have focused exclusively on direct neuron polarization, our hypothesis is that tDCS directly modulates endothelial cells leading to transient changes in blood-brain-barrier (BBB) permeability (P) that are highly meaningful for neuronal activity. For this, we developed state-of-the-art imaging and animal models to quantify P to various sized solutes after tDCS treatment. tDCS was administered using a constant current stimulator to deliver a 1mA current to the right frontal cortex of rat (approximately 2 mm posterior to bregma and 2 mm right to sagittal suture) to obtain similar physiological outcome as that in the human tDCS application studies. Sodium fluorescein (MW=376), or FITC-dextrans (20K and 70K), in 1% BSA mammalian Ringer was injected into the rat (SD, 250-300g) cerebral circulation via the ipsilateral carotid artery by a syringe pump at a constant rate of ~3 ml/min. To determine P, multiphoton microscopy with 800-850 nm wavelength laser was applied to take the images from the region of interest (ROI) with proper microvessels, which are 100-200 micron below the pia mater. It shows that the relative increase in P is about 8-fold for small solute, sodium fluorescein, ~35-fold for both intermediate sized (Dex-20k) and large (Dex-70k) solutes, 10 min after 20 min tDCS pretreatment. All of the increased permeability returns to the control after 20 min post treatment. The results confirmed our hypothesis.

Transcranial direct current stimulation effects in disorders of consciousness.

PubMed

Angelakis, Efthymios; Liouta, Evangelia; Andreadis, Nikos; Korfias, Stephanos; Ktonas, Periklis; Stranjalis, George; Sakas, Damianos E

2014-02-01

To assess the efficacy of transcranial direct current stimulation (tDCS) on improving consciousness in patients with persistent unresponsive wakefulness syndrome (UWS) (previously termed persistent vegetative state [PVS]) or in a minimally conscious state (MCS). Prospective, case series trial with follow-up at 12 months. General and research hospital. Inpatients in a PVS/UWS or MCS (N=10; 7 men, 3 women; age range, 19-62y; etiology: traumatic brain injury, n=5; anoxia, n=4; postoperative infarct, n=1; duration of PVS/UWS or MCS range, 6mo-10y). No participant withdrew because of adverse effects. All patients received sham tDCS for 20 minutes per day, 5 days per week, for 1 week, and real tDCS for 20 minutes per day, 5 days per week, for 2 weeks. An anodal electrode was placed over the left primary sensorimotor cortex or the left dorsolateral prefrontal cortex, with cathodal stimulation over the right eyebrow. One patient in an MCS received a second round of 10 tDCS sessions 3 months after initial participation. JFK Coma Recovery Scale-Revised. All patients in an MCS showed clinical improvement immediately after treatment. The patient who received a second round of tDCS 3 months after initial participation showed further improvement and emergence into consciousness after stimulation, with no change between treatments. One patient who was in an MCS for <1 year before treatment (postoperative infarct) showed further improvement and emergence into consciousness at 12-month follow-up. No patient showed improvement before stimulation. No patient in a PVS/UWS showed immediate improvement after stimulation, but 1 patient who was in a PVS/UWS for 6 years before treatment showed improvement and change of status to an MCS at 12-month follow-up. tDCS seems promising for the rehabilitation of patients with severe disorders of consciousness. Severity and duration of pathology may be related to the degree of tDCS' beneficial effects. Copyright © 2014 American Congress of

Transcranial direct current stimulation for the treatment of primary progressive aphasia: An open-label pilot study.

PubMed

Gervits, Felix; Ash, Sharon; Coslett, H Branch; Rascovsky, Katya; Grossman, Murray; Hamilton, Roy

2016-11-01

Primary progressive aphasia (PPA) is a neurodegenerative condition characterized by gradual deterioration of language function. We investigated whether two weeks of daily transcranial direct current stimulation (tDCS) treatment would improve language abilities in six people with a non-fluent form of PPA. tDCS was applied in an unblinded trial at an intensity of 1.5mA for 20min/day over 10days. At the time of stimulation, patients were engaged in narrating one of several children's wordless picture stories. A battery of neuropsychological assessments was administered four times: at baseline, immediately following the 2-week stimulation period, and then 6-weeks and 12-weeks following the end of stimulation. We observed improvement in linguistic performance in the domains of speech production and grammatical comprehension. Our encouraging results indicate that larger, sham-controlled studies of tDCS as a potential intervention for PPA are warranted. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Transcranial Direct Current Stimulation (tDCS) on Human Memory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzen, Laura E.; Trumbo, Michael Christopher Stefan

Training a person in a new knowledge base or skill set is extremely time consuming and costly, particularly in highly specialized domains such as the military and the intelligence community. Recent research in cognitive neuroscience has suggested that a technique called transcranial direct current stimulation (tDCS) has the potential to revolutionize training by enabling learners to acquire new skills faster, more efficiently, and more robustly (Bullard et al., 2011). In this project, we tested the effects of tDCS on two types of memory performance that are critical for learning new skills: associative memory and working memory. Associative memory is memorymore » for the relationship between two items or events. It forms the foundation of all episodic memories, so enhancing associative memory could provide substantial benefits to the speed and robustness of learning new information. We tested the effects of tDCS on associative memory, using a real-world associative memory task: remembering the links between faces and names. Working memory refers to the amount of information that can be held in mind and processed at one time, and it forms the basis for all higher-level cognitive processing. We investigated the degree of transfer between various working memory tasks (the N-back task as a measure of verbal working memory, the rotation-span task as a measure of visuospatial working memory, and Raven's progressive matrices as a measure of fluid intelligence) in order to determine if tDCS-induced facilitation of performance is task-specific or general.« less

Transcranial Direct Current Stimulation Effects on Semantic Processing in Healthy Individuals.

PubMed

Joyal, Marilyne; Fecteau, Shirley

2016-01-01

Semantic processing allows us to use conceptual knowledge about the world. It has been associated with a large distributed neural network that includes the frontal, temporal and parietal cortices. Recent studies using transcranial direct current stimulation (tDCS) also contributed at investigating semantic processing. The goal of this article was to review studies investigating semantic processing in healthy individuals with tDCS and discuss findings from these studies in line with neuroimaging results. Based on functional magnetic resonance imaging studies assessing semantic processing, we predicted that tDCS applied over the inferior frontal gyrus, middle temporal gyrus, and posterior parietal cortex will impact semantic processing. We conducted a search on Pubmed and selected 27 articles in which tDCS was used to modulate semantic processing in healthy subjects. We analysed each article according to these criteria: demographic information, experimental outcomes assessing semantic processing, study design, and effects of tDCS on semantic processes. From the 27 reviewed studies, 8 found main effects of stimulation. In addition to these 8 studies, 17 studies reported an interaction between stimulus types and stimulation conditions (e.g. incoherent functional, but not instrumental, actions were processed faster when anodal tDCS was applied over the posterior parietal cortex as compared to sham tDCS). Results suggest that regions in the frontal, temporal, and parietal cortices are involved in semantic processing. tDCS can modulate some aspects of semantic processing and provide information on the functional roles of brain regions involved in this cognitive process. Copyright © 2016 Elsevier Inc. All rights reserved.

Exploring the efficacy of a 5-day course of transcranial direct current stimulation (TDCS) on depression and memory function in patients with well-controlled temporal lobe epilepsy.

PubMed

Liu, Anli; Bryant, Andrew; Jefferson, Ashlie; Friedman, Daniel; Minhas, Preet; Barnard, Sarah; Barr, William; Thesen, Thomas; O'Connor, Margaret; Shafi, Mouhsin; Herman, Susan; Devinsky, Orrin; Pascual-Leone, Alvaro; Schachter, Steven

2016-02-01

Depression and memory dysfunction significantly impact the quality of life of patients with epilepsy. Current therapies for these cognitive and psychiatric comorbidities are limited. We explored the efficacy and safety of transcranial direct current stimulation (TDCS) for treating depression and memory dysfunction in patients with temporal lobe epilepsy (TLE). Thirty-seven (37) adults with well-controlled TLE were enrolled in a double-blinded, sham-controlled, randomized, parallel-group study of 5 days of fixed-dose (2 mA, 20 min) TDCS. Subjects were randomized to receive either real or sham TDCS, both delivered over the left dorsolateral prefrontal cortex. Patients received neuropsychological testing and a 20-minute scalp EEG at baseline immediately after the TDCS course and at 2- and 4-week follow-up. There was improvement in depression scores immediately after real TDCS, but not sham TDCS, as measured by changes in the Beck Depression Inventory (BDI change: -1.68 vs. 1.27, p<0.05) and NDDI-E (-0.83 vs. 0.9091, p=0.05). There was no difference between the groups at the 2- or 4-week follow-up. There was no effect on delayed or working memory performance. Transcranial direct current stimulation was well-tolerated and did not increase seizure frequency or interictal discharge frequency. Transcranial direct current stimulation induced an increase in delta frequency band power over the frontal region and delta, alpha, and theta band power in the occipital region after real stimulation compared to sham stimulation, although the difference did not reach statistical significance. This study provides evidence for the use of TDCS as a safe and well-tolerated nonpharmacologic approach to improving depressive symptoms in patients with well-controlled TLE. However, there were no changes in memory function immediately following or persisting after a stimulation course. Further studies may determine optimal stimulation parameters for maximal mood benefit. Copyright © 2015

The effect of transcranial direct current stimulation (tDCS) on locomotion and balance in patients with chronic stroke: study protocol for a randomised controlled trial.

PubMed

Geiger, M; Supiot, A; Zory, R; Aegerter, P; Pradon, D; Roche, N

2017-10-23

Following stroke, patients are often left with hemiparesis that reduces balance and gait capacity. A recent, non-invasive technique, transcranial direct current stimulation, can be used to modify cortical excitability when used in an anodal configuration. It also increases the excitability of spinal neuronal circuits involved in movement in healthy subjects. Many studies in patients with stroke have shown that this technique can improve motor, sensory and cognitive function. For example, anodal tDCS has been shown to improve motor performance of the lower limbs in patients with stroke, such as voluntary quadriceps strength, toe-pinch force and reaction time. Nevertheless, studies of motor function have been limited to simple tasks. Surprisingly, the effects of tDCS on the locomotion and balance of patients with chronic stroke have never been evaluated. In this study, we hypothesise that anodal tDCS will improve balance and gait parameters in patients with chronic stroke-related hemiparesis through its effects at cortical and spinal level. This is a prospective, randomised, placebo-controlled, double-blinded, single-centre, cross-over study over 36 months. Forty patients with chronic stroke will be included. Each patient will participate in three visits: an inclusion visit, and two visits during which they will all undergo either one 30-min session of transcranial direct current stimulation or one 30-min session of placebo stimulation in a randomised order. Evaluations will be carried out before, during and twice after stimulation. The primary outcome is the variability of the displacement of the centre of mass during gait and a static-balance task. Secondary outcomes include clinical and functional measures before and after stimulation. A three-dimensional gait analysis, and evaluation of static balance on a force platform will be also conducted before, during and after stimulation. These results should constitute a useful database to determine the aspects of

Modulation of Electrophysiology by Transcranial Direct Current Stimulation in Psychiatric Disorders: A Systematic Review.

PubMed

Kim, Minah; Kwak, Yoo Bin; Lee, Tae Young; Kwon, Jun Soo

2018-04-27

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique increasingly used to relieve symptoms of psychiatric disorders. Electrophysiologic markers, such as electroencephalography (EEG) and event-related potentials (ERP), have high temporal resolution sensitive to detect plastic changes of the brain associated with symptomatic improvement following tDCS application. We performed systematic review to identify electrophysiological markers that reflect tDCS effects on plastic brain changes in psychiatric disorders. A total of 638 studies were identified by searching PubMed, Embase, psychINFPO. Of these, 21 full-text articles were assessed eligible and included in the review. Although the reviewed studies were heterogeneous in their choices of tDCS protocols, targeted electrophysiological markers, and disease entities, their results strongly support EEG/ERPs to sensitively reflect plastic brain changes and the associated symptomatic improvement following tDCS. EEG/ERPs may serve a potent tool in revealing the mechanisms underlying psychiatric symptoms, as well as in localizing the brain area targeted for stimulation. Future studies in each disease entities employing consistent tDCS protocols and electrophysiological markers would be necessary in order to substantiate and further elaborate the findings of studies included in the present systematic review.

Reduction of chronic abdominal pain in patients with inflammatory bowel disease through transcranial direct current stimulation: a randomized controlled trial.

PubMed

Volz, Magdalena S; Farmer, Annabelle; Siegmund, Britta

2016-02-01

Inflammatory bowel disease (IBD) is frequently associated with chronic abdominal pain (CAP). Transcranial direct current stimulation (tDCS) has been proven to reduce chronic pain. This study aimed to investigate the effects of tDCS in patients with CAP due to IBD. This randomized, sham-controlled, double blind, parallel-designed study included 20 patients with either Crohn disease or ulcerative colitis with CAP (≥3/10 on the visual analog scale (VAS) in 3/6 months). Anodal or sham tDCS was applied over the primary motor cortex for 5 consecutive days (2 mA, 20 minutes). Assessments included VAS, pressure pain threshold, inflammatory markers, and questionnaires on quality of life, functional and disease specific symptoms (Irritable Bowel Syndrome-Severity Scoring System [IBS-SSS]), disease activity, and pain catastrophizing. Follow-up data were collected 1 week after the end of the stimulation. Statistical analyses were performed using analysis of variance and t tests. There was a significant reduction of abdominal pain in the anodal tDCS group compared with sham tDCS. This effect was evident in changes in VAS and pressure pain threshold on the left and right sides of the abdomen. In addition, 1 week after stimulation, pain reduction remained significantly decreased in the right side of the abdomen. There was also a significant reduction in scores on pain catastrophizing and on IBS-SSS when comparing both groups. Inflammatory markers and disease activity did not differ significantly between groups throughout the experiment. Transcranial direct current stimulation proved to be an effective and clinically relevant therapeutic strategy for CAP in IBD. The analgesic effects observed are unrelated to inflammation and disease activity, which emphasizes central pain mechanisms in CAP.

Feasibility of using high-definition transcranial direct current stimulation (HD-tDCS) to enhance treatment outcomes in persons with aphasia

PubMed Central

Richardson, Jessica; Datta, Abhishek; Dmochowski, Jacek; Parra, Lucas C.; Fridriksson, Julius

2018-01-01

BACKGROUND Transcranial direct current stimulation (tDCS) enhances treatment outcomes post-stroke. Feasibility and tolerability of high-definition (HD) tDCS (a technique that increases current focality and intensity) for consecutive weekdays as an adjuvant to behavioral treatment in a clinical population has not been demonstrated. OBJECTIVE To determine HD-tDCS feasibility outcomes: 1) ability to implement study as designed, 2) acceptability of repeated HD-tDCS administration to patients, and 3) preliminary efficacy. METHODS Eight patients with chronic post-stroke aphasia participated in a randomized crossover trial with two arms: conventional sponge-based (CS) tDCS and HD-tDCS. Computerized anomia treatment was administered for five consecutive days during each treatment arm. RESULTS Individualized modeling/targeting procedures and an 8-channel HD-tDCS device were developed. CS-tDCS and HD-tDCS were comparable in terms of implementation, acceptability, and outcomes. Naming accuracy and response time improved for both stimulation conditions. Change in accuracy of trained items was numerically higher (but not statistically significant) for HD-tDCS compared to CS-tDCS for most patients. CONCLUSIONS Regarding feasibility, HD-tDCS treatment studies can be implemented when designed similarly to documented CS-tDCS studies. HD-tDCS is likely to be acceptable to patients and clinicians. Preliminary efficacy data suggest that HD-tDCS effects, using only 4 electrodes, are at least comparable to CS-tDCS. PMID:25547776

Randomized trial of transcranial direct current stimulation for poststroke dysphagia.

PubMed

Suntrup-Krueger, Sonja; Ringmaier, Corinna; Muhle, Paul; Wollbrink, Andreas; Kemmling, Andre; Hanning, Uta; Claus, Inga; Warnecke, Tobias; Teismann, Inga; Pantev, Christo; Dziewas, Rainer

2018-02-01

We evaluated whether transcranial direct current stimulation (tDCS) is able to enhance dysphagia rehabilitation following stroke. Besides relating clinical effects with neuroplastic changes in cortical swallowing processing, we aimed to identify factors influencing treatment success. In this double-blind, randomized study, 60 acute dysphagic stroke patients received contralesional anodal (1mA, 20 minutes) or sham tDCS on 4 consecutive days. Swallowing function was thoroughly assessed before and after the intervention using the validated Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS) and clinical assessment. In 10 patients, swallowing-related brain activation was recorded applying magnetoencephalography before and after the intervention. Voxel-based statistical lesion pattern analysis was also performed. Study groups did not differ according to demographic data, stroke characteristics, or baseline dysphagia severity. Patients treated with tDCS showed greater improvement in FEDSS than the sham group (1.3 vs 0.4 points, mean difference = 0.9, 95% confidence interval [CI] = 0.4-1.4, p < 0.0005). Functional recovery was accompanied by a significant increase of activation (p < 0.05) in the contralesional swallowing network after real but not sham tDCS. Regarding predictors of treatment success, for every hour earlier that treatment was initiated, there was greater improvement on the FEDSS (adjusted odds ratio = 0.99, 95% CI = 0.98-1.00, p < 0.05) in multivariate analysis. Stroke location in the right insula and operculum was indicative of worse response to tDCS (p < 0.05). Application of tDCS over the contralesional swallowing motor cortex supports swallowing network reorganization, thereby leading to faster rehabilitation of acute poststroke dysphagia. Early treatment initiation seems beneficial. tDCS may be less effective in right-hemispheric insulo-opercular stroke. Ann Neurol 2018;83:328-340. © 2018 American Neurological

Evaluation of the effectiveness of transcranial direct current stimulation (tDCS) and psychosensory stimulation through DOCS scale in a minimally conscious subject.

PubMed

Dimitri, Danilo; De Filippis, Daniela; Galetto, Valentina; Zettin, Marina

2017-04-01

The aim of our study was to assess the effectiveness of transcranial direct current stimulation (tDCS) on alertness improvement in a patient in a minimally conscious state (MCS) by means of disorders of consciousness scale combined with psycho-sensory stimulation. The effects of tDCS on muscle hypertonia through the Ashworth scale were also examined. tDCS was performed through a two-channel intra-cephalic stimulator. After stimulation, the patient followed a psychosensory stimulation training. Results pointed out an increase in DOCunit score, as well as an increase in alertness maintenance and an improvement in muscle hypertonia, although a MCS state persisted.

The Influence of Skin Redness on Blinding in Transcranial Direct Current Stimulation Studies: A Crossover Trial.

PubMed

Ezquerro, Fernando; Moffa, Adriano H; Bikson, Marom; Khadka, Niranjan; Aparicio, Luana V M; de Sampaio-Junior, Bernardo; Fregni, Felipe; Bensenor, Isabela M; Lotufo, Paulo A; Pereira, Alexandre Costa; Brunoni, Andre R

2017-04-01

To evaluate whether and to which extent skin redness (erythema) affects investigator blinding in transcranial direct current stimulation (tDCS) trials. Twenty-six volunteers received sham and active tDCS, which was applied with saline-soaked sponges of different thicknesses. High-resolution skin images, taken before and 5, 15, and 30 min after stimulation, were randomized and presented to experienced raters who evaluated erythema intensity and judged on the likelihood of stimulation condition (sham vs. active). In addition, semi-automated image processing generated probability heatmaps and surface area coverage of erythema. Adverse events were also collected. Erythema was present, but less intense in sham compared to active groups. Erythema intensity was inversely and directly associated to correct sham and active stimulation group allocation, respectively. Our image analyses found that erythema also occurs after sham and its distribution is homogenous below electrodes. Tingling frequency was higher using thin compared to thick sponges, whereas erythema was more intense under thick sponges. Optimal investigator blinding is achieved when erythema after tDCS is mild. Erythema distribution under the electrode is patchy, occurs after sham tDCS and varies according to sponge thickness. We discuss methods to address skin erythema-related tDCS unblinding. © 2016 International Neuromodulation Society.

Systematic assessment of duration and intensity of anodal transcranial direct current stimulation on primary motor cortex excitability.

PubMed

Tremblay, Sara; Larochelle-Brunet, Félix; Lafleur, Louis-Philippe; El Mouderrib, Sofia; Lepage, Jean-François; Théoret, Hugo

2016-09-01

Since the initial demonstration of linear effects of stimulation duration and intensity on the strength of after-effects associated with transcranial direct current stimulation (tDCS), few studies have systematically assessed how varying these parameters modulates corticospinal excitability. Therefore, the objective of this study was to systematically evaluate the effects of anodal tDCS on corticospinal excitability at two stimulation intensities (1 mA, 2 mA) and durations (10 min, 20 min), and determine the value of several variables in predicting response. Two groups of 20 individuals received, in two separate sessions, 1 and 2 mA anodal tDCS (left primary motor cortex (M1)-right supra-orbital montage) for either 10- or 20-min. Transcranial magnetic stimulation was delivered over left M1 and motor evoked potentials (MEPs) of the contralateral hand were recorded prior to tDCS and every 5 min for 20-min post-tDCS. The following predictive variables were evaluated: I-wave recruitment, stimulation intensity, baseline M1 excitability and inter-trial MEP variability. Results show that anodal tDCS failed to significantly modulate corticospinal excitability in all conditions. Furthermore, low response rates were identified across all parameter combinations. No baseline measure was significantly correlated with increases in MEP amplitude. However, a decrease in inter-trial MEP variability was linked to response to anodal tDCS. In conclusion, the present findings are consistent with recent reports showing high levels of inter-subject variability in the neurophysiological response to tDCS, which may partly explain inconsistent group results. Furthermore, the level of variability in the neurophysiological outcome measure, i.e. MEPs, appears to be related to response. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Regulatory Considerations for the Clinical and Research Use of Transcranial Direct Current Stimulation (tDCS): review and recommendations from an expert panel

PubMed Central

Fregni, F; Nitsche, MA; Loo, C.K.; Brunoni, AR; Marangolo, P; Leite, J; Carvalho, S; Bolognini, N; Caumo, W; Paik, NJ; Simis, M; Ueda, K; Ekhitari, H; Luu, P; Tucker, DM; Tyler, WJ; Brunelin, J; Datta, A; Juan, CH; Venkatasubramanian, G; Boggio, PS; Bikson, M

2014-01-01

The field of transcranial electrical stimulation (tES) has experienced significant growth in the past 15 years. One of the tES techniques leading this increased interest is transcranial direct current stimulation (tDCS). Significant research efforts have been devoted to determining the clinical potential of tDCS in humans. Despite the promising results obtained with tDCS in basic and clinical neuroscience, further progress has been impeded by a lack of clarity on international regulatory pathways. We therefore convened a group of research and clinician experts on tDCS to review the research and clinical use of tDCS. In this report, we review the regulatory status of tDCS, and we summarize the results according to research, off-label and compassionate use of tDCS in the following countries: Australia, Brazil, France, Germany, India, Iran, Italy, Portugal, South Korea, Taiwan and United States. Research use, off label treatment and compassionate use of tDCS are employed in most of the countries reviewed in this study. It is critical that a global or local effort is organized to pursue definite evidence to either approve and regulate or restrict the use of tDCS in clinical practice on the basis of adequate randomized controlled treatment trials. PMID:25983531

Anodal transcranial direct current stimulation to the cerebellum improves handwriting and cyclic drawing kinematics in focal hand dystonia

PubMed Central

Bradnam, Lynley V.; Graetz, Lynton J.; McDonnell, Michelle N.; Ridding, Michael C.

2015-01-01

There is increasing evidence that the cerebellum has a role in the pathophysiology of primary focal hand dystonia and might provide an intervention target for non-invasive brain stimulation to improve function of the affected hand. The primary objective of this study was to determine if cerebellar transcranial direct current stimulation (tDCS) improves handwriting and cyclic drawing kinematics in people with hand dystonia, by reducing cerebellar-brain inhibition (CBI) evoked by transcranial magnetic stimulation (TMS). Eight people with dystonia (5 writer’s dystonia, 3 musician’s dystonia) and eight age-matched controls completed the study and underwent cerebellar anodal, cathodal and sham tDCS in separate sessions. Dystonia severity was assessed using the Writer’s Cramp Rating Scale (WRCS) and the Arm Dystonia Disability Scale (ADDS). The kinematic measures that differentiated the groups were; mean stroke frequency during handwriting and fast cyclic drawing and average pen pressure during light cyclic drawing. TMS measures of cortical excitability were no different between people with FHD and controls. There was a moderate, negative relationship between TMS-evoked CBI at baseline and the WRCS in dystonia. Anodal cerebellar tDCS reduced handwriting mean stroke frequency and average pen pressure, and increased speed and reduced pen pressure during fast cyclic drawing. Kinematic measures were not associated with a decrease in CBI within an individual. In conclusion, cerebellar anodal tDCS appeared to improve kinematics of handwriting and circle drawing tasks; but the underlying neurophysiological mechanism remains uncertain. A study in a larger homogeneous population is needed to further investigate the possible therapeutic benefit of cerebellar tDCS in dystonia. PMID:26042019

Behavioural and neurofunctional impact of transcranial direct current stimulation on somatosensory learning.

PubMed

Hilgenstock, Raphael; Weiss, Thomas; Huonker, Ralph; Witte, Otto W

2016-04-01

We investigated the effect of repeated delivery of anodal transcranial direct current stimulation (tDCS) on somatosensory performance and long-term learning. Over the course of five days, tDCS was applied to the primary somatosensory cortex (S1) by means of neuronavigation employing magnetencephalography (MEG). Compared to its sham application, tDCS promoted tactile learning by reducing the two-point discrimination threshold assessed by the grating orientation task (GOT) primarily by affecting intersessional changes in performance. These results were accompanied by alterations in the neurofunctional organization of the brain, as revealed by functional magnetic resonance imaging conducted prior to the study, at the fifth day of tDCS delivery and four weeks after the last application of tDCS. A decrease in activation at the primary site of anodal tDCS delivery in the left S1 along retention of superior tactile acuity was observed at follow-up four weeks after the application of tDCS. Thus, we demonstrate long-term effects that repeated tDCS imposes on somatosensory functioning. This is the first study to provide insight into the mode of operation of tDCS on the brain's response to long-term perceptual learning, adding an important piece of evidence from the domain of non-invasive brain stimulation to show that functional changes detectable by fMRI in primary sensory cortices participate in perceptual learning. © 2016 Wiley Periodicals, Inc.

Effects of transcranial direct current stimulation (tDCS) on binge eating disorder.

PubMed

Burgess, Emilee E; Sylvester, Maria D; Morse, Kathryn E; Amthor, Frank R; Mrug, Sylvie; Lokken, Kristine L; Osborn, Mary K; Soleymani, Taraneh; Boggiano, Mary M

2016-10-01

To investigate the effect of transcranial direct current stimulation (tDCS) on food craving, intake, binge eating desire, and binge eating frequency in individuals with binge eating disorder (BED). N = 30 adults with BED or subthreshold BED received a 20-min 2 milliampere (mA) session of tDCS targeting the dorsolateral prefrontal cortex (DLPFC; anode right/cathode left) and a sham session. Food image ratings assessed food craving, a laboratory eating test assessed food intake, and an electronic diary recorded binge variables. tDCS versus sham decreased craving for sweets, savory proteins, and an all-foods category, with strongest reductions in men (p < 0.05). tDCS also decreased total and preferred food intake by 11 and 17.5%, regardless of sex (p < 0.05), and reduced desire to binge eat in men on the day of real tDCS administration (p < 0.05). The reductions in craving and food intake were predicted by eating less frequently for reward motives, and greater intent to restrict calories, respectively. This proof of concept study is the first to find ameliorating effects of tDCS in BED. Stimulation of the right DLPFC suggests that enhanced cognitive control and/or decreased need for reward may be possible functional mechanisms. The results support investigation of repeated tDCS as a safe and noninvasive treatment adjunct for BED. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2016; 49:930-936). © 2016 Wiley Periodicals, Inc.

Categorization is modulated by transcranial direct current stimulation over left prefrontal cortex.

PubMed

Lupyan, Gary; Mirman, Daniel; Hamilton, Roy; Thompson-Schill, Sharon L

2012-07-01

Humans have an unparalleled ability to represent objects as members of multiple categories. A given object, such as a pillow may be-depending on current task demands-represented as an instance of something that is soft, as something that contains feathers, as something that is found in bedrooms, or something that is larger than a toaster. This type of processing requires the individual to dynamically highlight task-relevant properties and abstract over or suppress object properties that, although salient, are not relevant to the task at hand. Neuroimaging and neuropsychological evidence suggests that this ability may depend on cognitive control processes associated with the left inferior prefrontal gyrus. Here, we show that stimulating the left inferior frontal cortex using transcranial direct current stimulation alters performance of healthy subjects on a simple categorization task. Our task required subjects to select pictures matching a description, e.g., "click on all the round things." Cathodal stimulation led to poorer performance on classification trials requiring attention to specific dimensions such as color or shape as opposed to trials that required selecting items belonging to a more thematic category such as objects that hold water. A polarity reversal (anodal stimulation) lowered the threshold for selecting items that were more weakly associated with the target category. These results illustrate the role of frontally-mediated control processes in categorization and suggest potential interactions between categorization, cognitive control, and language. Copyright © 2012 Elsevier B.V. All rights reserved.

Can Transcranial Direct Current Stimulation Improve Cognitive Functioning in Adults with Schizophrenia?

PubMed

Schretlen, David J; van Steenburgh, Joseph J; Varvaris, Mark; Vannorsdall, Tracy D; Andrejczuk, Megan A; Gordon, Barry

Cognitive impairment is nearly ubiquitous in schizophrenia. First-degree relatives of persons with schizophrenia often show similar but milder deficits. Current methods for the treatment of schizophrenia are often ineffective in cognitive remediation. Since transcranial direct current stimulation (tDCS) can enhance cognitive functioning in healthy adults, it might provide a viable option to enhance cognition in schizophrenia. We sought to explore whether tDCS can be tolerated by persons with schizophrenia and potentially improve their cognitive functioning. We examined the effects of anodal versus cathodal tDCS on working memory and other cognitive tasks in five outpatients with schizophrenia and six first-degree relatives of persons with schizophrenia. Each participant completed tasks thought to be mediated by the prefrontal cortex during two 30-minute sessions of tDCS to the left and right dorsolateral prefrontal cortex (DLPFC). Anodal stimulation over the left DLPFC improved performance relative to cathodal stimulation on measures of working memory and aspects of verbal fluency relevant to word retrieval. The patient group showed differential changes in novel design production without alteration of overall productivity, suggesting that tDCS might be capable of altering self-monitoring and executive control. All participants tolerated tDCS well. None withdrew from the study or experienced any adverse reaction. We conclude that adults with schizophrenia can tolerate tDCS while engaging in cognitive tasks and that tDCS can alter their performance.

Transcranial Direct Current Stimulation Modulates Neuronal Networks in Attention Deficit Hyperactivity Disorder.

PubMed

Sotnikova, Anna; Soff, Cornelia; Tagliazucchi, Enzo; Becker, Katja; Siniatchkin, Michael

2017-09-01

Anodal transcranial direct current stimulation (tDCS) of the prefrontal cortex has been repeatedly shown to improve working memory (WM). Since patients with attention deficit hyperactivity disorder (ADHD) are characterized by both underactivation of the prefrontal cortex and deficits in WM, the modulation of prefrontal activity with tDCS in ADHD patients may increase their WM performance as well as improve the activation and connectivity of the WM network. In the present study, this hypothesis was tested using a double-blind sham-controlled experimental design. After randomization, sixteen adolescents with ADHD underwent either anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC, 1 mA, 20 min) or sham stimulation with simultaneous fMRI during n-back WM task. Both in one-back and two-back conditions, tDCS led to a greater activation (compared with sham stimulation) of the left DLPFC (under the electrode), left premotor cortex, left supplementary motor cortex, and precuneus. The effects of tDCS were long-lasting and influenced resting state functional connectivity even 20 min after the stimulation, with patterns of strengthened DLPFC connectivity after tDCS outlining the WM network. In summary, anodal tDCS caused increased neuronal activation and connectivity, not only in the brain area under the stimulating electrode (i.e. left DLPFC) but also in other, more remote brain regions. Because of moderate behavioral effects of tDCS, the significance of this technique for ADHD treatment has to be investigated in further studies.

Modulation of Total Sleep Time by Transcranial Direct Current Stimulation (tDCS)

PubMed Central

Frase, Lukas; Piosczyk, Hannah; Zittel, Sulamith; Jahn, Friederike; Selhausen, Peter; Krone, Lukas; Feige, Bernd; Mainberger, Florian; Maier, Jonathan G; Kuhn, Marion; Klöppel, Stefan; Normann, Claus; Sterr, Annette; Spiegelhalder, Kai; Riemann, Dieter; Nitsche, Michael A; Nissen, Christoph

2016-01-01

Arousal and sleep are fundamental physiological processes, and their modulation is of high clinical significance. This study tested the hypothesis that total sleep time (TST) in humans can be modulated by the non-invasive brain stimulation technique transcranial direct current stimulation (tDCS) targeting a ‘top-down' cortico-thalamic pathway of sleep-wake regulation. Nineteen healthy participants underwent a within-subject, repeated-measures protocol across five nights in the sleep laboratory with polysomnographic monitoring (adaptation, baseline, three experimental nights). tDCS was delivered via bi-frontal target electrodes and bi-parietal return electrodes before sleep (anodal ‘activation', cathodal ‘deactivation', and sham stimulation). Bi-frontal anodal stimulation significantly decreased TST, compared with cathodal and sham stimulation. This effect was location specific. Bi-frontal cathodal stimulation did not significantly increase TST, potentially due to ceiling effects in good sleepers. Exploratory resting-state EEG analyses before and after the tDCS protocols were consistent with the notion of increased cortical arousal after anodal stimulation and decreased cortical arousal after cathodal stimulation. The study provides proof-of-concept that TST can be decreased by non-invasive bi-frontal anodal tDCS in healthy humans. Further elucidating the ‘top-down' pathway of sleep-wake regulation is expected to increase knowledge on the fundamentals of sleep-wake regulation and to contribute to the development of novel treatments for clinical conditions of disturbed arousal and sleep. PMID:27143601

Validation of finite element model of transcranial electrical stimulation using scalp potentials: implications for clinical dose

NASA Astrophysics Data System (ADS)

Datta, Abhishek; Zhou, Xiang; Su, Yuzhou; Parra, Lucas C.; Bikson, Marom

2013-06-01

Objective. During transcranial electrical stimulation, current passage across the scalp generates voltage across the scalp surface. The goal was to characterize these scalp voltages for the purpose of validating subject-specific finite element method (FEM) models of current flow. Approach. Using a recording electrode array, we mapped skin voltages resulting from low-intensity transcranial electrical stimulation. These voltage recordings were used to compare the predictions obtained from the high-resolution model based on the subject undergoing transcranial stimulation. Main results. Each of the four stimulation electrode configurations tested resulted in a distinct distribution of scalp voltages; these spatial maps were linear with applied current amplitude (0.1 to 1 mA) over low frequencies (1 to 10 Hz). The FEM model accurately predicted the distinct voltage distributions and correlated the induced scalp voltages with current flow through cortex. Significance. Our results provide the first direct model validation for these subject-specific modeling approaches. In addition, the monitoring of scalp voltages may be used to verify electrode placement to increase transcranial electrical stimulation safety and reproducibility.

Clinical Applications of Transcranial Magnetic Stimulation in Pediatric Neurology.

PubMed

Narayana, Shalini; Papanicolaou, Andrew C; McGregor, Amy; Boop, Frederick A; Wheless, James W

2015-08-01

Noninvasive brain stimulation is now an accepted technique that is used as a diagnostic aid and in the treatment of neuropsychiatric disorders in adults, and is being increasingly used in children. In this review, we will discuss the basic principles and safety of one noninvasive brain stimulation method, transcranial magnetic stimulation. Improvements in the spatial accuracy of transcranial magnetic stimulation are described in the context of image-guided transcranial magnetic stimulation. The article describes and provides examples of the current clinical applications of transcranial magnetic stimulation in children as an aid in the diagnosis and treatment of neuropsychiatric disorders and discusses future potential applications. Transcranial magnetic stimulation is a noninvasive tool that is safe for use in children and adolescents for functional mapping and treatment, and for many children it aids in the preoperative evaluation and the risk-benefit decision making. © The Author(s) 2014.

Intensity dependent effects of transcranial direct current stimulation on corticospinal excitability in chronic spinal cord injury.

PubMed

Murray, Lynda M; Edwards, Dylan J; Ruffini, Giulio; Labar, Douglas; Stampas, Argyrios; Pascual-Leone, Alvaro; Cortes, Mar

2015-04-01

To investigate the effects of anodal transcranial direct current stimulation (a-tDCS) intensity on corticospinal excitability and affected muscle activation in individuals with chronic spinal cord injury (SCI). Single-blind, randomized, sham-controlled, crossover study. Medical research institute and rehabilitation hospital. Volunteers (N = 9) with chronic SCI and motor dysfunction in wrist extensor muscles. Three single session exposures to 20 minutes of a-tDCS (anode over the extensor carpi radialis [ECR] muscle representation on the left primary motor cortex, cathode over the right supraorbital area) using 1 mA, 2 mA, or sham stimulation, delivered at rest, with at least 1 week between sessions. Corticospinal excitability was assessed with motor-evoked potentials (MEPs) from the ECR muscle using surface electromyography after transcranial magnetic stimulation. Changes in spinal excitability, sensory threshold, and muscle strength were also investigated. Mean MEP amplitude significantly increased by approximately 40% immediately after 2mA a-tDCS (pre: 0.36 ± 0.1 mV; post: 0.47 ± 0.11 mV; P = .001), but not with 1 mA or sham. Maximal voluntary contraction measures remained unaltered across all conditions. Sensory threshold significantly decreased over time after 1mA (P = .002) and 2mA (P = .039) a-tDCS and did not change with sham. F-wave persistence showed a nonsignificant trend for increase (pre: 32% ± 12%; post: 41% ± 10%; follow-up: 46% ± 12%) after 2 mA stimulation. No adverse effects were reported with any of the experimental conditions. The a-tDCS can transiently raise corticospinal excitability to affected muscles in patients with chronic SCI after 2 mA stimulation. Sensory perception can improve with both 1 and 2 mA stimulation. This study gives support to the safe and effective use of a-tDCS using small electrodes in patients with SCI and highlights the importance of stimulation intensity. Copyright © 2015 American Congress of Rehabilitation

Transcranial direct current stimulation on primary sensorimotor area has no effect in patients with drug-naïve restless legs syndrome: a proof-of-concept clinical trial.

PubMed

Koo, Yong Seo; Kim, Sung Min; Lee, Chany; Lee, Byeong Uk; Moon, Ye Ji; Cho, Yong Won; Im, Chang-Hwan; Choi, Jeong Woo; Kim, Kyung Hwan; Jung, Ki-Young

2015-02-01

To evaluate the efficacy of transcranial direct current stimulation (tDCS) in people with drug-naïve restless legs syndrome (RLS). A two-week, double-blind, randomized, sham-controlled trial was performed. Thirty-three females with RLS were recruited. Participants received five sessions of tDCS using cathodal, anodal or sham stimulation. They were assessed at baseline (T0), three days (T1) and 13 days (T2) after the end of tDCS. Primary outcomes included the International RLS Group Rating Scale (IRLS) and the Clinical Global Impressions-Improvement (CGI-I). Secondary outcomes included the Patient Global Impression scale, the Pittsburgh Sleep Quality Index, the Medical Outcome Study sleep subscales, and the Beck Depression Inventory. Objective neurophysiological changes were assessed using event-related desynchronization/synchronization (ERD/ERS) of electroencephalography. The changes in the IRLS scores, as well as the responder rate in the CGI-I scale, did not differ significantly among the groups. There was also no significant difference in any of the secondary outcome measures and ERD/ERS among the groups. Transcranial direct current stimulation with electrodes on the sensorimotor areas showed no significant effect in people with drug-naïve RLS. Copyright © 2014 Elsevier B.V. All rights reserved.

Modelling the effect of electrode displacement on transcranial direct current stimulation (tDCS)

NASA Astrophysics Data System (ADS)

Ramaraju, Sriharsha; Roula, Mohammed A.; McCarthy, Peter W.

2018-02-01

Objective. Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers a low-intensity, direct current to cortical areas with the purpose of modulating underlying brain activity. Recent studies have reported inconsistencies in tDCS outcomes. The underlying assumption of many tDCS studies has been that replication of electrode montage equates to replicating stimulation conditions. It is possible however that anatomical difference between subjects, as well as inherent inaccuracies in montage placement, could affect current flow to targeted areas. The hypothesis that stimulation of a defined brain region will be stable under small displacements was tested. Approach. Initially, we compared the total simulated current flowing through ten specific brain areas for four commonly used tDCS montages: F3-Fp2, C3-Fp2, Fp1-F4, and P3-P4 using the software tool COMETS. The effect of a slight (~1 cm in each of four directions) anode displacement on the simulated regional current density for each of the four tDCS montages was then determined. Current flow was calculated and compared through ten segmented brain areas to determine the effect of montage type and displacement. The regional currents, as well as the localised current densities, were compared with the original electrode location, for each of these new positions. Main results. Recommendations for montages that maximise stimulation current for the ten brain regions are considered. We noted that the extent to which stimulation is affected by electrode displacement varies depending on both area and montage type. The F3-Fp2 montage was found to be the least stable with up to 38% change in average current density in the left frontal lobe while the Fp1-F4 montage was found to the most stable exhibiting only 1% change when electrodes were displaced. Significance. These results indicate that even relatively small changes in stimulation electrode placement appear to result in surprisingly large

High-definition transcranial direct current stimulation (HD-tDCS) of left dorsolateral prefrontal cortex affects performance in Balloon Analogue Risk Task (BART).

PubMed

Guo, Heng; Zhang, Zhuoran; Da, Shu; Sheng, Xiaotian; Zhang, Xichao

2018-02-01

Studies on risk preferences have long been of great concern and have examined the neural basis underlying risk-based decision making. However, studies using conventional transcranial direct current stimulation (tDCS) revealed that bilateral stimulation could change risk propensity with limited evidence of precisely focalized unilateral high-definition transcranial direct current stimulation (HD-tDCS). The aim of this experiment was to investigate the effect of HD-tDCS focalizing the left dorsal lateral prefrontal cortex (DLPFC) on risk-taking behavior during the Balloon Analogue Risk Task (BART). This study was designed as a between-subject, single-blind, sham-controlled experiment. University students were randomly assigned to three groups: the anodal group (F3 anode, AF3, F1, F5, FC3 returned), the cathodal group (F3 cathodal, AF3, F1, F5, FC3 returned) and the sham group. Subsequently, 1.5-mA 20-min HD-tDCS was applied during the BART, and the Positive Affect and Negative Affect Scale (PANAS), the Sensation Seeking Scale-5 (SSS-5), and the Behavioral Inhibition System and Behavioral Approach System scale (BIS/BAS) were measured as control variables. The cathodal group earned less total money than the sham group, and no significant difference was observed between the anodal group and the sham group. These results showed that, to some extent, focalized unilateral cathodal HD-tDCS on left DLPFC could change performance during risky tasks and diminish risky decision making. Further studies are needed to investigate the dose effect and electrode distribution of HD-tDCS during risky tasks and examine synchronous brain activity to show the neural basis.

Direct bonded HOPG - Analyzer support without background source

NASA Astrophysics Data System (ADS)

Groitl, Felix; Kitaura, Hidetoshi; Nishiki, Naomi; Rønnow, Henrik M.

2018-04-01

A new production process allows a direct bonding of HOPG crystals on Si wafers. This new method facilitates the production of analyzer crystals with support structure without the use of additional, background inducing fixation material, e.g. glue, wax and screws. This new method is especially interesting for the upcoming generation of CAMEA-type multiplexing spectrometers. These instruments allow for a drastic performance increase due to the increased angular coverage and multiple energy analysis. Exploiting the transparency of multiple HOPG for cold neutrons, a consecutive arrangement of HOPG analyzer crystals per Q-channel can be achieved. This implies that neutrons travel through up to 10 arrays of analyzer crystals before reaching the analyzer corresponding to their energy. Hence, a careful choice of the fixation method for the analyzer crystals in regards to transparency and background is necessary. Here, we present first results on the diffraction and mechanical performance of direct bonded analyzer crystals.

Transcranial Magnetic Stimulation in Child Neurology: Current and Future Directions

PubMed Central

Frye, Richard E.; Rotenberg, Alexander; Ousley, Molliann; Pascual-Leone, Alvaro

2008-01-01

Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation based on the principle of electromagnetic induction, where small intracranial electric currents are generated by a powerful, rapidly changing extracranial magnetic field. Over the past 2 decades TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disease in adults, but has been used on a more limited basis in children. We reviewed the literature to identify potential diagnostic and therapeutic applications of TMS in child neurology and also its safety in pediatrics. Although TMS has not been associated with any serious side effects in children and appears to be well tolerated, general safety guidelines should be established. The potential for applications of TMS in child neurology and psychiatry is significant. Given its excellent safety profile and possible therapeutic effect, this technique should develop as an important tool in pediatric neurology over the next decade. PMID:18056688

Transcranial Duplex Sonography Predicts Outcome following an Intracerebral Hemorrhage.

PubMed

Camps-Renom, P; Méndez, J; Granell, E; Casoni, F; Prats-Sánchez, L; Martínez-Domeño, A; Guisado-Alonso, D; Martí-Fàbregas, J; Delgado-Mederos, R

2017-08-01

Several radiologic features such as hematoma volume are related to poor outcome following an intracerebral hemorrhage and can be measured with transcranial duplex sonography. We sought to determine the prognostic value of transcranial duplex sonography in patients with intracerebral hemorrhage. We conducted a prospective study of patients diagnosed with spontaneous intracerebral hemorrhage. Transcranial duplex sonography examinations were performed within 2 hours of baseline CT, and we recorded the following variables: hematoma volume, midline shift, third ventricle and lateral ventricle diameters, and the pulsatility index in both MCAs. We correlated these data with the CT scans and assessed the prognostic value of the transcranial duplex sonography measurements. We assessed early neurologic deterioration during hospitalization and mortality at 1-month follow-up. We included 35 patients with a mean age of 72.2 ± 12.8 years. Median baseline hematoma volume was 9.85 mL (interquartile range, 2.74-68.29 mL). We found good agreement and excellent correlation between transcranial duplex sonography and CT when measuring hematoma volume ( r = 0.791; P < .001) and midline shift ( r = 0.827; P < .001). The logistic regression analysis with transcranial duplex sonography measurements showed that hematoma volume was an independent predictor of early neurologic deterioration (OR, 1.078; 95% CI, 1.023-1.135) and mortality (OR, 1.089; 95% CI, 1.020-1.160). A second regression analysis with CT variables also demonstrated that hematoma volume was associated with early neurologic deterioration and mortality. When we compared the rating operation curves of both models, their predictive power was similar. Transcranial duplex sonography showed an excellent correlation with CT in assessing hematoma volume and midline shift in patients with intracerebral hemorrhage. Hematoma volume measured with transcranial duplex sonography was an independent predictor of poor outcome. © 2017 by

Battery powered thought: enhancement of attention, learning, and memory in healthy adults using transcranial direct current stimulation.

PubMed

Coffman, Brian A; Clark, Vincent P; Parasuraman, Raja

2014-01-15

This article reviews studies demonstrating enhancement with transcranial direct current stimulation (tDCS) of attention, learning, and memory processes in healthy adults. Given that these are fundamental cognitive functions, they may also mediate stimulation effects on other higher-order processes such as decision-making and problem solving. Although tDCS research is still young, there have been a variety of methods used and cognitive processes tested. While these different methods have resulted in seemingly contradictory results among studies, many consistent and noteworthy effects of tDCS on attention, learning, and memory have been reported. The literature suggests that although tDCS as typically applied may not be as useful for localization of function in the brain as some other methods of brain stimulation, tDCS may be particularly well-suited for practical applications involving the enhancement of attention, learning, and memory, in both healthy subjects and in clinical populations. © 2013 Elsevier Inc. All rights reserved.

Classification of methods in transcranial electrical stimulation (tES) and evolving strategy from historical approaches to contemporary innovations.

PubMed

Guleyupoglu, Berkan; Schestatsky, Pedro; Edwards, Dylan; Fregni, Felipe; Bikson, Marom

2013-10-15

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES. Copyright © 2013 Elsevier B.V. All rights reserved.

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

PubMed Central

Guleyupoglu, Berkan; Schestatsky, Pedro; Edwards, Dylan; Fregni, Felipe; Bikson, Marom

2013-01-01

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of trans-cranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES. PMID:23954780

Transcranial infrared laser stimulation improves rule-based, but not information-integration, category learning in humans.

PubMed

Blanco, Nathaniel J; Saucedo, Celeste L; Gonzalez-Lima, F

2017-03-01

This is the first randomized, controlled study comparing the cognitive effects of transcranial laser stimulation on category learning tasks. Transcranial infrared laser stimulation is a new non-invasive form of brain stimulation that shows promise for wide-ranging experimental and neuropsychological applications. It involves using infrared laser to enhance cerebral oxygenation and energy metabolism through upregulation of the respiratory enzyme cytochrome oxidase, the primary infrared photon acceptor in cells. Previous research found that transcranial infrared laser stimulation aimed at the prefrontal cortex can improve sustained attention, short-term memory, and executive function. In this study, we directly investigated the influence of transcranial infrared laser stimulation on two neurobiologically dissociable systems of category learning: a prefrontal cortex mediated reflective system that learns categories using explicit rules, and a striatally mediated reflexive learning system that forms gradual stimulus-response associations. Participants (n=118) received either active infrared laser to the lateral prefrontal cortex or sham (placebo) stimulation, and then learned one of two category structures-a rule-based structure optimally learned by the reflective system, or an information-integration structure optimally learned by the reflexive system. We found that prefrontal rule-based learning was substantially improved following transcranial infrared laser stimulation as compared to placebo (treatment X block interaction: F(1, 298)=5.117, p=0.024), while information-integration learning did not show significant group differences (treatment X block interaction: F(1, 288)=1.633, p=0.202). These results highlight the exciting potential of transcranial infrared laser stimulation for cognitive enhancement and provide insight into the neurobiological underpinnings of category learning. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of slow repetitive transcranial magnetic stimulation in patients with corticobasal syndrome.

PubMed

Civardi, Carlo; Pisano, Fabrizio; Delconte, Carmen; Collini, Alessandra; Monaco, Francesco

2015-06-01

Corticobasal syndrome is characterized by asymmetric cortical sensorimotor dysfunction and parkinsonism; an altered cortical excitability has been reported. We explored with transcranial magnetic stimulation the motor cortical excitability in corticobasal syndrome, and the effects of slow repetitive transcranial magnetic stimulation. With transcranial magnetic stimulation, we studied two corticobasal syndrome patients. We determined bilaterally from the first dorsal interosseous muscle: relaxed threshold, and contralateral and ipsilateral silent period. We also evaluated the contralateral silent period after active/sham slow repetitive transcranial magnetic stimulation on the most affected side. At T0 the silent period was bilaterally short. On the most affected side, active slow repetitive transcranial magnetic stimulation induced a short lasting prolongation of the contralateral silent period. In corticobasal syndrome, transcranial magnetic stimulation showed a reduction cortical inhibitory phenomenon potentially reversed transiently by slow repetitive transcranial magnetic stimulation.

Transcranial Electrical Neuromodulation Based on the Reciprocity Principle

PubMed Central

Fernández-Corazza, Mariano; Turovets, Sergei; Luu, Phan; Anderson, Erik; Tucker, Don

2016-01-01

A key challenge in multi-electrode transcranial electrical stimulation (TES) or transcranial direct current stimulation (tDCS) is to find a current injection pattern that delivers the necessary current density at a target and minimizes it in the rest of the head, which is mathematically modeled as an optimization problem. Such an optimization with the Least Squares (LS) or Linearly Constrained Minimum Variance (LCMV) algorithms is generally computationally expensive and requires multiple independent current sources. Based on the reciprocity principle in electroencephalography (EEG) and TES, it could be possible to find the optimal TES patterns quickly whenever the solution of the forward EEG problem is available for a brain region of interest. Here, we investigate the reciprocity principle as a guideline for finding optimal current injection patterns in TES that comply with safety constraints. We define four different trial cortical targets in a detailed seven-tissue finite element head model, and analyze the performance of the reciprocity family of TES methods in terms of electrode density, targeting error, focality, intensity, and directionality using the LS and LCMV solutions as the reference standards. It is found that the reciprocity algorithms show good performance comparable to the LCMV and LS solutions. Comparing the 128 and 256 electrode cases, we found that use of greater electrode density improves focality, directionality, and intensity parameters. The results show that reciprocity principle can be used to quickly determine optimal current injection patterns in TES and help to simplify TES protocols that are consistent with hardware and software availability and with safety constraints. PMID:27303311

Transcranial Electrical Neuromodulation Based on the Reciprocity Principle.

PubMed

Fernández-Corazza, Mariano; Turovets, Sergei; Luu, Phan; Anderson, Erik; Tucker, Don

2016-01-01

A key challenge in multi-electrode transcranial electrical stimulation (TES) or transcranial direct current stimulation (tDCS) is to find a current injection pattern that delivers the necessary current density at a target and minimizes it in the rest of the head, which is mathematically modeled as an optimization problem. Such an optimization with the Least Squares (LS) or Linearly Constrained Minimum Variance (LCMV) algorithms is generally computationally expensive and requires multiple independent current sources. Based on the reciprocity principle in electroencephalography (EEG) and TES, it could be possible to find the optimal TES patterns quickly whenever the solution of the forward EEG problem is available for a brain region of interest. Here, we investigate the reciprocity principle as a guideline for finding optimal current injection patterns in TES that comply with safety constraints. We define four different trial cortical targets in a detailed seven-tissue finite element head model, and analyze the performance of the reciprocity family of TES methods in terms of electrode density, targeting error, focality, intensity, and directionality using the LS and LCMV solutions as the reference standards. It is found that the reciprocity algorithms show good performance comparable to the LCMV and LS solutions. Comparing the 128 and 256 electrode cases, we found that use of greater electrode density improves focality, directionality, and intensity parameters. The results show that reciprocity principle can be used to quickly determine optimal current injection patterns in TES and help to simplify TES protocols that are consistent with hardware and software availability and with safety constraints.

Modulation of electric brain responses evoked by pitch deviants through transcranial direct current stimulation.

PubMed

Royal, Isabelle; Zendel, Benjamin Rich; Desjardins, Marie-Ève; Robitaille, Nicolas; Peretz, Isabelle

2018-01-31

Congenital amusia is a neurodevelopmental disorder, characterized by a difficulty detecting pitch deviation that is related to abnormal electrical brain responses. Abnormalities found along the right fronto-temporal pathway between the inferior frontal gyrus (IFG) and the auditory cortex (AC) are the likely neural mechanism responsible for amusia. To investigate the causal role of these regions during the detection of pitch deviants, we applied cathodal (inhibitory) transcranial direct current stimulation (tDCS) over right frontal and right temporal regions during separate testing sessions. We recorded participants' electrical brain activity (EEG) before and after tDCS stimulation while they performed a pitch change detection task. Relative to a sham condition, there was a decrease in P3 amplitude after cathodal stimulation over both frontal and temporal regions compared to pre-stimulation baseline. This decrease was associated with small pitch deviations (6.25 cents), but not large pitch deviations (200 cents). Overall, this demonstrates that using tDCS to disrupt regions around the IFG and AC can induce temporary changes in evoked brain activity when processing pitch deviants. These electrophysiological changes are similar to those observed in amusia and provide causal support for the connection between P3 and fronto-temporal brain regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-Definition transcranial direct current stimulation in early onset epileptic encephalopathy: a case study.

PubMed

Meiron, Oded; Gale, Rena; Namestnic, Julia; Bennet-Back, Odeya; David, Jonathan; Gebodh, Nigel; Adair, Devin; Esmaeilpour, Zeinab; Bikson, Marom

2018-01-01

Early onset epileptic encephalopathy is characterized by high daily seizure-frequency, multifocal epileptic discharges, severe psychomotor retardation, and death at infancy. Currently, there are no effective treatments to alleviate seizure frequency and high-voltage epileptic discharges in these catastrophic epilepsy cases. The current study examined the safety and feasibility of High-Definition transcranial direct current stimulation (HD-tDCS) in reducing epileptiform activity in a 30-month-old child suffering from early onset epileptic encephalopathy. HD-tDCS was administered over 10 intervention days spanning two weeks including pre- and post-intervention video-EEG monitoring. There were no serious adverse events or side effects related to the HD-tDCS intervention. Frequency of clinical seizures was not significantly reduced. However, interictal sharp wave amplitudes were significantly lower during the post-intervention period versus baseline. Vital signs and blood biochemistry remained stable throughout the entire study. These exploratory findings support the safety and feasibility of 4 × 1 HD-tDCS in early onset epileptic encephalopathy and provide the first evidence of HD-tDCS effects on paroxysmal EEG features in electroclinical cases under the age of 36 months. Extending HD-tDCS treatment may enhance electrographic findings and clinical effects.

Transcranial Direct Current Stimulation in Substance Use Disorders: A Systematic Review of Scientific Literature.

PubMed

Lupi, Matteo; Martinotti, Giovanni; Santacroce, Rita; Cinosi, Eduardo; Carlucci, Maria; Marini, Stefano; Acciavatti, Tiziano; di Giannantonio, Massimo

2017-09-01

New treatment options such as noninvasive brain stimulation have been recently explored in the field of substance use disorders (SUDs), including transcranial direct current stimulation (tDCS). In light of this, we have performed a review of the scientific literature to assess efficacy and technical and methodological issues resulting from applying tDCS to the field of SUDs. Our analysis highlighted the following selection criteria: clinical studies on tDCS and SUDs (alcohol, caffeine, cannabis, cocaine, heroin, methamphetamine, and nicotine). Study selection, data analysis, and reporting were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Exclusion criteria were as follows: clinical studies about tDCS among behavioral addiction; review and didactic articles; physiopathological studies; and case reports. Eighteen scientific papers were selected out of 48 articles. Among these, 16 studied the efficacy of tDCS applied to the dorsolateral prefrontal cortex, and 8 suggested the efficacy of tDCS in reducing substance craving. In light of these data, it is premature to conclude that tDCS over the dorsolateral prefrontal cortex is a very efficient technique in reducing craving. Small sample size, different stimulation protocols, and study duration were the main limitations. However, the efficacy of tDCS in treating SUDs requires further investigation.

Transcranial direct current stimulation associated with gait training in Parkinson's disease: A pilot randomized clinical trial.

PubMed

Costa-Ribeiro, Adriana; Maux, Ariadne; Bosford, Thamyris; Aoki, Yumi; Castro, Rebeca; Baltar, Adriana; Shirahige, Lívia; Moura Filho, Alberto; Nitsche, Michael A; Monte-Silva, Kátia

2017-04-01

The aim of this study is to investigate the effects of transcranial direct current stimulation (tDCS) combined with cueing gait training (CGT) on functional mobility in patients with Parkinson´s disease (PD). A pilot double-blind controlled, randomized clinical trial was conducted with 22 patients with PD assigned to the experimental (anodal tDCS plus CGT) and control group (sham tDCS plus CGT). The primary outcome (functional mobility) was assessed by 10-m walk test, cadence, stride length, and Timed Up and Go test. Motor impairment, bradykinesia, balance, and quality of life were analyzed as secondary outcomes. Minimal clinically important differences (MCIDs) were observed when assessing outcome data. Both groups demonstrated similar gains in all outcome measures, except for the stride length. The number of participants who showed MCID was similar between groups. The CGT provided many benefits to functional mobility, motor impairment, bradykinesia, balance, and quality of life. However, these effect magnitudes were not influenced by stimulation, but tDCS seems to prolong the effects of cueing therapy on functional mobility.

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

PubMed Central

Behrens, Janina R.; Kraft, Antje; Irlbacher, Kerstin; Gerhardt, Holger; Olma, Manuel C.; Brandt, Stephan A.

2017-01-01

Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2–4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability. PMID:28860969

Transcranial Direct Current Stimulation of the Left Dorsolateral Prefrontal Cortex Shifts Preference of Moral Judgments

PubMed Central

Kuehne, Maria; Heimrath, Kai; Heinze, Hans-Jochen; Zaehle, Tino

2015-01-01

Attitude to morality, reflecting cultural norms and values, is considered unique to human social behavior. Resulting moral behavior in a social environment is controlled by a widespread neural network including the dorsolateral prefrontal cortex (DLPFC), which plays an important role in decision making. In the present study we investigate the influence of neurophysiological modulation of DLPFC reactivity by means of transcranial direct current stimulation (tDCS) on moral reasoning. For that purpose we administered anodal, cathodal, and sham stimulation of the left DLPFC while subjects judged the appropriateness of hard moral personal dilemmas. In contrast to sham and cathodal stimulation, anodal stimulation induced a shift in judgment of personal moral dilemmas towards more non-utilitarian actions. Our results demonstrate that alterations of left DLPFC activity can change moral judgments and, in consequence, provide a causal link between left DLPFC activity and moral reasoning. Most important, the observed shift towards non-utilitarian actions suggests that moral decision making is not a permanent individual trait but can be manipulated; consequently individuals with boundless, uncontrollable, and maladaptive moral behavior, such as found in psychopathy, might benefit from neuromodulation-based approaches. PMID:25985442

[PM₂.₅ Background Concentration at Different Directions in Beijing in 2013].

PubMed

Li, Yun-ting; Cheng, Niam-liang; Zhang, Da-wei; Sun, Rui-wen; Dong, Xin; Sun, Nai-di; Chen, Chen

2015-12-01

PM₂.₅, background concentration at different directions in 2013 in Beijing was analyzed combining the techniques of mathematical statistics, physical identification and numerical simulation (CMAQ4.7.1) as well as using monitoring data of six PM₂.₅ auto-monitoring sites and five meteorological sites in 2013. Results showed that background concentrations of PM₂.₅ at northwest, northeast, eastern, southeast, southern and southwest boundary sites were between 40.3 and 85.3 µg · m⁻³ in Beijing. From the lowest to the highest, PMPM₂.₅ background concentrations at different sites were: Miyun reservoir, Badaling, Donggaocun, Yufa, Yongledian and Liulihe. Background concentration of PM₂.₅ was the lowest under north wind, then under west wind, and significantly higher under south and east wind. Calculated PM₂.₅ background average concentrations were 6.5-27.9, 22.4-73.4, 67.2-91.7, 40.7-116.1 µg · m⁻³ respectively in different wind directions. Simulated PM₂.₅ background concentration showed a clear north-south gradient distribution and the surrounding area had a notable effect on the spatial distribution of PM₂.₅ background concentration in 2013 in Beijing.

Activation of the prefrontal cortex by unilateral transcranial direct current stimulation leads to an asymmetrical effect on risk preference in frames of gain and loss.

PubMed

Ye, Hang; Huang, Daqiang; Wang, Siqi; Zheng, Haoli; Luo, Jun; Chen, Shu

2016-10-01

Previous brain imaging and brain stimulation studies have suggested that the dorsolateral prefrontal cortex may be critical in regulating risk-taking behavior, although its specific causal effect on people's risk preference remains controversial. This paper studied the independent modulation of the activity of the right and left dorsolateral prefrontal cortex using various configurations of transcranial direct current stimulation. We designed a risk-measurement table and adopted a within-subject design to compare the same participant's risk preference before and after unilateral stimulation when presented with different frames of gain and loss. The results confirmed a hemispheric asymmetry and indicated that the right dorsolateral prefrontal cortex has an asymmetric effect on risk preference regarding frames of gain and loss. Enhancing the activity of the right dorsolateral prefrontal cortex significantly decreased the participants' degree of risk aversion in the gain frame, whereas it increased the participants' degree of risk aversion in the loss frame. Our findings provide important information regarding the impact of transcranial direct current stimulation on the risk preference of healthy participants. The effects observed in our experiment compared with those of previous studies provide further evidence of the effects of hemispheric and frame-dependent asymmetry. These findings may be helpful in understanding the neural basis of risk preference in humans, especially when faced with decisions involving possible gain or loss relative to the status quo. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of anodal transcranial direct current stimulation over the leg motor area on lumbar spinal network excitability in healthy subjects

PubMed Central

Roche, N; Lackmy, A; Achache, V; Bussel, B; Katz, R

2011-01-01

Abstract In recent years, two techniques have become available for the non-invasive stimulation of human motor cortex: transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). The effects of TMS and tDCS when applied over motor cortex should be considered with regard not only to cortical circuits but also to spinal motor circuits. The different modes of action and specificity of TMS and tDCS suggest that their effects on spinal network excitability may be different from that in the cortex. Until now, the effects of tDCS on lumbar spinal network excitability have never been studied. In this series of experiments, on healthy subjects, we studied the effects of anodal tDCS over the lower limb motor cortex on (i) reciprocal Ia inhibition projecting from the tibialis anterior muscle (TA) to the soleus (SOL), (ii) presynaptic inhibition of SOL Ia terminals, (iii) homonymous SOL recurrent inhibition, and (iv) SOL H-reflex recruitment curves. The results show that anodal tDCS decreases reciprocal Ia inhibition, increases recurrent inhibition and induces no modification of presynaptic inhibition of SOL Ia terminals and of SOL-H reflex recruitment curves. Our results indicate therefore that the effects of tDCS are the opposite of those previously described for TMS on spinal network excitability. They also indicate that anodal tDCS induces effects on spinal network excitability similar to those observed during co-contraction suggesting that anodal tDCS activates descending corticospinal projections mainly involved in co-contractions. PMID:21502292

Stimulation of Dorsolateral Prefrontal Cortex Enhances Adaptive Cognitive Control: A High-Definition Transcranial Direct Current Stimulation Study.

PubMed

Gbadeyan, Oyetunde; McMahon, Katie; Steinhauser, Marco; Meinzer, Marcus

2016-12-14

Conflict adaptation is a hallmark effect of adaptive cognitive control and refers to the adjustment of control to the level of previously experienced conflict. Conflict monitoring theory assumes that the dorsolateral prefrontal cortex (DLPFC) is causally involved in this adjustment. However, to date, evidence in humans is predominantly correlational, and heterogeneous with respect to the lateralization of control in the DLPFC. We used high-definition transcranial direct current stimulation (HD-tDCS), which allows for more focal current delivery than conventional tDCS, to clarify the causal involvement of the DLPFC in conflict adaptation. Specifically, we investigated the regional specificity and lateralization of potential beneficial stimulation effects on conflict adaptation during a visual flanker task. One hundred twenty healthy participants were assigned to four HD-tDCS conditions: left or right DLPFC or left or right primary motor cortex (M1). Each group underwent both active and sham HD-tDCS in crossover, double-blind designs. We obtained a sizeable conflict adaptation effect (measured as the modulation of the flanker effect as a function of previous response conflict) in all groups and conditions. However, this effect was larger under active HD-tDCS than under sham stimulation in both DLPFC groups. In contrast, active stimulation had no effect on conflict adaptation in the M1 groups. In sum, the present results indicate that the DLPFC plays a causal role in adaptive cognitive control, but that the involvement of DLPFC in control is not restricted to the left or right hemisphere. Moreover, our study confirms the potential of HD-tDCS to modulate cognition in a regionally specific manner. Conflict adaptation is a hallmark effect of adaptive cognitive control. While animal studies have suggested causal involvement of the DLPFC in this phenomenon, such evidence is currently lacking in humans. The present study used high-definition transcranial direct current

International randomized-controlled trial of transcranial Direct Current Stimulation in depression.

PubMed

Loo, Colleen K; Husain, Mustafa M; McDonald, William M; Aaronson, Scott; O'Reardon, John P; Alonzo, Angelo; Weickert, Cynthia Shannon; Martin, Donel M; McClintock, Shawn M; Mohan, Adith; Lisanby, Sarah H

Evidence suggests that transcranial Direct Current Stimulation (tDCS) has antidepressant effects in unipolar depression, but there is limited information for patients with bipolar depression. Additionally, prior research suggests that brain derived neurotrophic factor (BDNF) Val66Met genotype may moderate response to tDCS. To examine tDCS efficacy in unipolar and bipolar depression and assess if BDNF genotype is associated with antidepressant response to tDCS. 130 participants diagnosed with a major depressive episode were randomized to receive active (2.5 milliamps (mA), 30 min) or sham (0.034 mA and two 60-second current ramps up to 1 and 0.5 mA) tDCS to the left prefrontal cortex, administered in 20 sessions over 4 weeks, in a double-blinded, international multisite study. Mixed effects repeated measures analyses assessed change in mood and neuropsychological scores in participants with at least one post-baseline rating in the unipolar (N = 84) and bipolar (N = 36) samples. Mood improved significantly over the 4-week treatment period in both unipolar (p = 0.001) and bipolar groups (p < 0.001). Among participants with unipolar depression, there were more remitters in the sham treatment group (p = 0.03). There was no difference between active and sham stimulation in the bipolar sample. BDNF genotype was unrelated to antidepressant outcome. Overall, this study found no antidepressant difference between active and sham stimulation for unipolar or bipolar depression. However, the possibility that the low current delivered in the sham tDCS condition was biologically active cannot be discounted. Moreover, BDNF genotype did not moderate antidepressant outcome. www.clinicaltrials.gov, NCT01562184. Copyright © 2017 Elsevier Inc. All rights reserved.

Repeated transcranial direct current stimulation reduces food craving in Wistar rats.

PubMed

Macedo, I C; de Oliveira, C; Vercelino, R; Souza, A; Laste, G; Medeiros, L F; Scarabelot, V L; Nunes, E A; Kuo, J; Fregni, F; Caumo, W; Torres, I L S

2016-08-01

It has been suggested that food craving-an intense desire to consume a specific food (particularly foods high in sugar and fat)-can lead to obesity. This behavior has also been associated with abuse of other substances, such as drugs. Both drugs and food cause dependence by acting on brain circuitry involved in reward, motivation, and decision-making processes. The dorsolateral prefrontal cortex (DLPFC) can be activated following evocation and is implicated in alterations in food behavior and craving. Transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique capable of modulates brain activity significantly, has emerged as a promising treatment to inhibit craving. This technique is considered safe and inexpensive; however, there is scant research using animal models. Such studies could help elucidate the behavioral and molecular mechanisms of eating disorders, including food craving. The aim of our study was to evaluate palatable food consumption in rats receiving tDCS treatment (anode right/cathode left). Eighteen adult male Wistar rats were randomized by weight and divided into three groups (n = 6/group): control, with no stimulation; sham, receiving daily 30 s tDCS (500 μA) sessions for 8 consecutive days; and tDCS, receiving daily 20 min tDCS (500 μA) sessions for 8 consecutive days. All rats were evaluated for locomotor activity and anxiety-like behavior. A palatable food consumption test was performed at baseline and on treatment completion (24 h after the last tDCS session) under fasting and feeding conditions and showed that tDCS decreased food craving, thus corroborating human studies. This result confirms the important role of the prefrontal cortex in food behavior, which can be modulated by noninvasive brain stimulation. Copyright © 2016. Published by Elsevier Ltd.

Transcranial direct current stimulation can enhance working memory in Huntington's disease.

PubMed

Eddy, Clare M; Shapiro, Kimron; Clouter, Andrew; Hansen, Peter C; Rickards, Hugh E

2017-07-03

Transcranial direct current stimulation (tDCS) combined with a cognitive task can enhance targeted aspects of cognitive functioning in clinical populations. The movement disorder Huntington's disease (HD) is associated with progressive cognitive impairment. Deficits in working memory (WM) can be apparent early in the disease and impact functional capacity. We investigated whether tDCS combined with cognitive training could improve WM in patients with HD, and if baseline clinical or cognitive measures may predict efficacy. Twenty participants with HD completed this crossover trial, undergoing 1.5mA anodal tDCS over left dorsolateral prefrontal cortex and sham stimulation on separate visits. Participants and assessor were blinded to condition order, which was randomised across participants. All participants completed baseline clinical and cognitive assessments. Pre- and post-stimulation tasks included digit reordering, computerised n-back tests and a Stroop task. During 15min of tDCS/sham stimulation, participants practiced 1- and 2-back WM tasks. Participants exhibited an increase in WM span on the digit re-ordering span task from pre- to post-stimulation after tDCS, but not after sham stimulation. Gains in WM were positively related to motor symptom ratings and negatively associated with verbal fluency scores. Patients with more severe motor symptoms showed greatest improvement, suggesting that motor symptom ratings may help identify patients who are most likely to benefit from tDCS. Dorsolateral prefrontal tDCS appears well tolerated in HD and enhances WM span compared to sham stimulation. Our findings strongly encourage further investigation of the extent to which tDCS combined with cognitive training could enhance everyday function in HD. ClinicalTrials.gov; NCT02216474 Brain stimulation in Movement Disorders; https://clinicaltrials.gov/ct2/show/NCT02216474. Copyright © 2017 Elsevier Inc. All rights reserved.

The association of motor imagery and kinesthetic illusion prolongs the effect of transcranial direct current stimulation on corticospinal tract excitability.

PubMed

Kaneko, Fuminari; Shibata, Eriko; Hayami, Tatsuya; Nagahata, Keita; Aoyama, Toshiyuki

2016-04-15

A kinesthetic illusion induced by a visual stimulus (KI) can produce vivid kinesthetic perception. During KI, corticospinal tract excitability increases and results in the activation of cerebral networks. Transcranial direct current stimulation (tDCS) is emerging as an alternative potential therapeutic modality for a variety of neurological and psychiatric conditions, such that identifying factors that enhance the magnitude and duration of tDCS effects is currently a topic of great scientific interest. This study aimed to establish whether the combination of tDCS with KI and sensory-motor imagery (MI) induces larger and longer-lasting effects on the excitability of corticomotor pathways in healthy Japanese subjects. A total of 21 healthy male volunteers participated in this study. Four interventions were investigated in the first experiment: (1) anodal tDCS alone (tDCSa), (2) anodal tDCS with visually evoked kinesthetic illusion (tDCSa + KI), (3) anodal tDCS with motor imagery (tDCSa + MI), and (4) anodal tDCS with kinesthetic illusion and motor imagery (tDCSa + KIMI). In the second experiment, we added a sham tDCS intervention with kinesthetic illusion and motor imagery (sham + KIMI) as a control for the tDCSa + KIMI condition. Direct currents were applied to the right primary motor cortex. Corticospinal excitability was examined using transcranial magnetic stimulation of the area associated with the left first dorsal interosseous. In the first experiment, corticomotor excitability was sustained for at least 30 min following tDCSa + KIMI (p < 0.01). The effect of tDCSa + KIMI on corticomotor excitability was greater and longer-lasting than that achieved in all other conditions. In the second experiment, significant effects were not achieved following sham + KIMI. Our results suggest that tDCSa + KIMI has a greater therapeutic potential than tDCS alone for inducing higher excitability of the corticospinal tract. The observed

Does transcranial electrical stimulation enhance corticospinal excitability of the motor cortex in healthy individuals? A systematic review and meta-analysis.

PubMed

Dissanayaka, Thusharika; Zoghi, Maryam; Farrell, Michael; Egan, Gary F; Jaberzadeh, Shapour

2017-08-01

Numerous studies have explored the effects of transcranial electrical stimulation (tES) - including anodal transcranial direct current stimulation (a-tDCS), cathodal transcranial direct current stimulation (c-tDCS), transcranial alternative current stimulation (tACS), transcranial random noise stimulation (tRNS) and transcranial pulsed current stimulation (tPCS) - on corticospinal excitability (CSE) in healthy populations. However, the efficacy of these techniques and their optimal parameters for producing robust results has not been studied. Thus, the aim of this systematic review was to consolidate current knowledge about the effects of various parameters of a-tDCS, c-tDCS, tACS, tRNS and tPCS on the CSE of the primary motor cortex (M1) in healthy people. Leading electronic databases were searched for relevant studies published between January 1990 and February 2017; 126 articles were identified, and their results were extracted and analysed using RevMan software. The meta-analysis showed that a-tDCS application on the dominant side significantly increases CSE (P < 0.01) and that the efficacy of a-tDCS is dependent on current density and duration of application. Similar results were obtained for stimulation of M1 on the non-dominant side (P = 0.003). The effects of a-tDCS reduce significantly after 24 h (P = 0.006). Meta-analysis also revealed significant reduction in CSE following c-tDCS (P < 0.001) and significant increases after tRNS (P = 0.03) and tPCS (P = 0.01). However, tACS effects on CSE were only significant when the stimulation frequency was ≥140 Hz. This review provides evidence that tES has substantial effects on CSE in healthy individuals for a range of stimulus parameters. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Rigor and reproducibility in research with transcranial electrical stimulation: An NIMH-sponsored workshop.

PubMed

Bikson, Marom; Brunoni, Andre R; Charvet, Leigh E; Clark, Vincent P; Cohen, Leonardo G; Deng, Zhi-De; Dmochowski, Jacek; Edwards, Dylan J; Frohlich, Flavio; Kappenman, Emily S; Lim, Kelvin O; Loo, Colleen; Mantovani, Antonio; McMullen, David P; Parra, Lucas C; Pearson, Michele; Richardson, Jessica D; Rumsey, Judith M; Sehatpour, Pejman; Sommers, David; Unal, Gozde; Wassermann, Eric M; Woods, Adam J; Lisanby, Sarah H

Neuropsychiatric disorders are a leading source of disability and require novel treatments that target mechanisms of disease. As such disorders are thought to result from aberrant neuronal circuit activity, neuromodulation approaches are of increasing interest given their potential for manipulating circuits directly. Low intensity transcranial electrical stimulation (tES) with direct currents (transcranial direct current stimulation, tDCS) or alternating currents (transcranial alternating current stimulation, tACS) represent novel, safe, well-tolerated, and relatively inexpensive putative treatment modalities. This report seeks to promote the science, technology and effective clinical applications of these modalities, identify research challenges, and suggest approaches for addressing these needs in order to achieve rigorous, reproducible findings that can advance clinical treatment. The National Institute of Mental Health (NIMH) convened a workshop in September 2016 that brought together experts in basic and human neuroscience, electrical stimulation biophysics and devices, and clinical trial methods to examine the physiological mechanisms underlying tDCS/tACS, technologies and technical strategies for optimizing stimulation protocols, and the state of the science with respect to therapeutic applications and trial designs. Advances in understanding mechanisms, methodological and technological improvements (e.g., electronics, computational models to facilitate proper dosing), and improved clinical trial designs are poised to advance rigorous, reproducible therapeutic applications of these techniques. A number of challenges were identified and meeting participants made recommendations made to address them. These recommendations align with requirements in NIMH funding opportunity announcements to, among other needs, define dosimetry, demonstrate dose/response relationships, implement rigorous blinded trial designs, employ computational modeling, and demonstrate

Transcranial magnetic stimulation-induced global propagation of transient phase resetting associated with directional information flow.

PubMed

Kawasaki, Masahiro; Uno, Yutaka; Mori, Jumpei; Kobata, Kenji; Kitajo, Keiichi

2014-01-01

Electroencephalogram (EEG) phase synchronization analyses can reveal large-scale communication between distant brain areas. However, it is not possible to identify the directional information flow between distant areas using conventional phase synchronization analyses. In the present study, we applied transcranial magnetic stimulation (TMS) to the occipital area in subjects who were resting with their eyes closed, and analyzed the spatial propagation of transient TMS-induced phase resetting by using the transfer entropy (TE), to quantify the causal and directional flow of information. The time-frequency EEG analysis indicated that the theta (5 Hz) phase locking factor (PLF) reached its highest value at the distant area (the motor area in this study), with a time lag that followed the peak of the transient PLF enhancements of the TMS-targeted area at the TMS onset. Phase-preservation index (PPI) analyses demonstrated significant phase resetting at the TMS-targeted area and distant area. Moreover, the TE from the TMS-targeted area to the distant area increased clearly during the delay that followed TMS onset. Interestingly, the time lags were almost coincident between the PLF and TE results (152 vs. 165 ms), which provides strong evidence that the emergence of the delayed PLF reflects the causal information flow. Such tendencies were observed only in the higher-intensity TMS condition, and not in the lower-intensity or sham TMS conditions. Thus, TMS may manipulate large-scale causal relationships between brain areas in an intensity-dependent manner. We demonstrated that single-pulse TMS modulated global phase dynamics and directional information flow among synchronized brain networks. Therefore, our results suggest that single-pulse TMS can manipulate both incoming and outgoing information in the TMS-targeted area associated with functional changes.

Low-frequency repetitive transcranial magnetic simulation prevents chronic epileptic seizure

PubMed Central

Wang, Yinxu; Wang, Xiaoming; Ke, Sha; Tan, Juan; Hu, Litian; Zhang, Yaodan; Cui, Wenjuan

2013-01-01

Although low-frequency repetitive transcranial magnetic simulation can potentially treat epilepsy, its underlying mechanism remains unclear. This study investigated the influence of low-frequency re-petitive transcranial magnetic simulation on changes in several nonlinear dynamic electroence-phalographic parameters in rats with chronic epilepsy and explored the mechanism underlying petitive transcranial magnetic simulation-induced antiepileptic effects. An epilepsy model was es-tablished using lithium-pilocarpine intraperitoneal injection into adult Sprague-Dawley rats, which were then treated with repetitive transcranial magnetic simulation for 7 consecutive days. Nonlinear electroencephalographic parameters were obtained from the rats at 7, 14, and 28 days post-stimulation. Results showed significantly lower mean correlation-dimension and Kolmogo-rov-entropy values for stimulated rats than for non-stimulated rats. At 28 days, the complexity and point-wise correlation dimensional values were lower in stimulated rats. Low-frequency repetitive transcranial magnetic simulation has suppressive effects on electrical activity in epileptic rats, thus explaining its effectiveness in treating epilepsy. PMID:25206567

Clinician accessible tools for GUI computational models of transcranial electrical stimulation: BONSAI and SPHERES.

PubMed

Truong, Dennis Q; Hüber, Mathias; Xie, Xihe; Datta, Abhishek; Rahman, Asif; Parra, Lucas C; Dmochowski, Jacek P; Bikson, Marom

2014-01-01

Computational models of brain current flow during transcranial electrical stimulation (tES), including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), are increasingly used to understand and optimize clinical trials. We propose that broad dissemination requires a simple graphical user interface (GUI) software that allows users to explore and design montages in real-time, based on their own clinical/experimental experience and objectives. We introduce two complimentary open-source platforms for this purpose: BONSAI and SPHERES. BONSAI is a web (cloud) based application (available at neuralengr.com/bonsai) that can be accessed through any flash-supported browser interface. SPHERES (available at neuralengr.com/spheres) is a stand-alone GUI application that allow consideration of arbitrary montages on a concentric sphere model by leveraging an analytical solution. These open-source tES modeling platforms are designed go be upgraded and enhanced. Trade-offs between open-access approaches that balance ease of access, speed, and flexibility are discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

Safety and Feasibility of Transcranial Direct Current Stimulation in Pediatric Hemiparesis: Randomized Controlled Preliminary Study

PubMed Central

Feyma, Tim; Menk, Jeremiah; Usset, Michelle; Vaith, Amy; Wood, Teddi Jean; Worthington, Rebecca; Krach, Linda E.

2015-01-01

Background Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that has shown improved adult stroke outcomes. Applying tDCS in children with congenital hemiparesis has not yet been explored. Objective The primary objective of this study was to explore the safety and feasibility of single-session tDCS through an adverse events profile and symptom assessment within a double-blind, randomized placebo-controlled preliminary study in children with congenital hemiparesis. A secondary objective was to assess the stability of hand and cognitive function. Design A double-blind, randomized placebo-controlled pretest/posttest/follow-up study was conducted. Setting The study was conducted in a university pediatric research laboratory. Participants Thirteen children, ages 7 to 18 years, with congenital hemiparesis participated. Measurements Adverse events/safety assessment and hand function were measured. Intervention Participants were randomly assigned to either an intervention group or a control group, with safety and functional assessments at pretest, at posttest on the same day, and at a 1-week follow-up session. An intervention of 10 minutes of 0.7 mA tDCS was applied to bilateral primary motor cortices. The tDCS intervention was considered safe if there was no individual decline of 25% or group decline of 2 standard deviations for motor evoked potentials (MEPs) and behavioral data and no report of adverse events. Results No major adverse events were found, including no seizures. Two participants did not complete the study due to lack of MEP and discomfort. For the 11 participants who completed the study, group differences in MEPs and behavioral data did not exceed 2 standard deviations in those who received the tDCS (n=5) and those in the control group (n=6). The study was completed without the need for stopping per medical monitor and biostatisticial analysis. Limitations A limitation of the study was the small sample size, with data

Transcranial direct current stimulation combined with integrative speech therapy in a child with cerebral palsy: A case report.

PubMed

Carvalho Lima, Vania L C; Collange Grecco, Luanda A; Marques, Valéria C; Fregni, Felipe; Brandão de Ávila, Clara R

2016-04-01

The aim of this study was to describe the results of the first case combining integrative speech therapy with anodal transcranial direct current stimulation (tDCS) over Broca's area in a child with cerebral palsy. The ABFW phonology test was used to analyze speech based on the Percentage of Correct Consonants (PCC) and Percentage of Correct Consonants - Revised (PCC-R). After treatment, increases were found in both PCC (Imitation: 53.63%-78.10%; Nomination: 53.19%-70.21%) and PPC-R (Imitation: 64.54%-83.63%; Nomination: 61.70%-77.65%). Moreover, reductions occurred in distortions, substitutions and improvement was found in oral performance, especially tongue mobility (AMIOFE-mobility before = 4 after = 7). The child demonstrated a clinically important improvement in speech fluency as shown in results of imitation number of correct consonants and phonemes acquire. Based on these promising findings, continuing research in this field should be conducted with controlled clinical trials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anodal transcranial direct current stimulation boosts synaptic plasticity and memory in mice via epigenetic regulation of Bdnf expression

PubMed Central

Podda, Maria Vittoria; Cocco, Sara; Mastrodonato, Alessia; Fusco, Salvatore; Leone, Lucia; Barbati, Saviana Antonella; Colussi, Claudia; Ripoli, Cristian; Grassi, Claudio

2016-01-01

The effects of transcranial direct current stimulation (tDCS) on brain functions and the underlying molecular mechanisms are yet largely unknown. Here we report that mice subjected to 20-min anodal tDCS exhibited one-week lasting increases in hippocampal LTP, learning and memory. These effects were associated with enhanced: i) acetylation of brain-derived neurotrophic factor (Bdnf) promoter I; ii) expression of Bdnf exons I and IX; iii) Bdnf protein levels. The hippocampi of stimulated mice also exhibited enhanced CREB phosphorylation, pCREB binding to Bdnf promoter I and recruitment of CBP on the same regulatory sequence. Inhibition of acetylation and blockade of TrkB receptors hindered tDCS effects at molecular, electrophysiological and behavioral levels. Collectively, our findings suggest that anodal tDCS increases hippocampal LTP and memory via chromatin remodeling of Bdnf regulatory sequences leading to increased expression of this gene, and support the therapeutic potential of tDCS for brain diseases associated with impaired neuroplasticity. PMID:26908001

Effect of Anodal and Cathodal Transcranial Direct Current Stimulation on DLPFC on Modulation of Inhibitory Control in ADHD.

PubMed

Soltaninejad, Zahra; Nejati, Vahid; Ekhtiari, Hamed

2015-12-20

The purpose of this study was to improve the inhibitory control functions through transcranial direct current stimulation (tDCS) in adolescents with ADHD symptoms. Twenty high school students with ADHD symptoms participated in this single-blinded, crossover, sham-controlled study. All the participants were tested during the application of Stroop and Go/No-Go tasks that is used to measure inhibitory control, using 1.5 mA of tDCS for 15 min over the left dorsolateral prefrontal cortex (DLPFC). Anodal stimulation on left DLPFC had no effect on interference inhibition during the Stroop task and increased the proportion of correct responses in the "Go stage" of the Go/No-Go test compared with sham condition. Cathodal stimulation on the left DLPFC increased the inhibition accuracy in the inhibition stage during Go/No-Go task in comparison with sham. tDCS over the left DLPFC of adolescents who suffer from ADHD symptoms can improve inhibitory control in prepotent response inhibition. © The Author(s) 2015.

Transcranial direct current stimulation of the medial prefrontal cortex dampens mind-wandering in men.

PubMed

Bertossi, Elena; Peccenini, Ludovica; Solmi, Andrea; Avenanti, Alessio; Ciaramelli, Elisa

2017-12-05

Mind-wandering, the mind's capacity to stray from external events and generate task-unrelated thought, has been associated with activity in the brain default network. To date, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated the role of medial prefrontal cortex (mPFC) in mind-wandering, by perturbing this region with transcranial direct current stimulation (tDCS). Young healthy participants performed a choice reaction time task both before and after receiving cathodal tDCS over mPFC, and had their thoughts periodically sampled. We found that tDCS over mPFC - but not occipital or sham tDCS - decreased the propensity to mind-wander. The tDCS-induced reduction in mind-wandering occurred in men, but not in women, and was accompanied by a change in the content of task-unrelated though, which became more related to other people (as opposed to the self) following tDCS. These findings indicate that mPFC is crucial for mind-wandering, possibly by helping construction of self-relevant scenarios capable to divert attention inward, away from perceptual reality. Gender-related differences in tDCS-induced changes suggest that mPFC controls mind-wandering differently in men and women, which may depend on differences in the structural and functional organization of distributed brain networks governing mind-wandering, including mPFC.

Changing head model extent affects finite element predictions of transcranial direct current stimulation distributions

NASA Astrophysics Data System (ADS)

Indahlastari, Aprinda; Chauhan, Munish; Schwartz, Benjamin; Sadleir, Rosalind J.

2016-12-01

Objective. In this study, we determined efficient head model sizes relative to predicted current densities in transcranial direct current stimulation (tDCS). Approach. Efficiency measures were defined based on a finite element (FE) simulations performed using nine human head models derived from a single MRI data set, having extents varying from 60%-100% of the original axial range. Eleven tissue types, including anisotropic white matter, and three electrode montages (T7-T8, F3-right supraorbital, Cz-Oz) were used in the models. Main results. Reducing head volume extent from 100% to 60%, that is, varying the model’s axial range from between the apex and C3 vertebra to one encompassing only apex to the superior cerebellum, was found to decrease the total modeling time by up to half. Differences between current density predictions in each model were quantified by using a relative difference measure (RDM). Our simulation results showed that {RDM} was the least affected (a maximum of 10% error) for head volumes modeled from the apex to the base of the skull (60%-75% volume). Significance. This finding suggested that the bone could act as a bioelectricity boundary and thus performing FE simulations of tDCS on the human head with models extending beyond the inferior skull may not be necessary in most cases to obtain reasonable precision in current density results.

Frontal Transcranial Direct Current Stimulation Induces Dopamine Release in the Ventral Striatum in Human

PubMed Central

Fonteneau, Clara; Redoute, Jérome; Haesebaert, Frédéric; Le Bars, Didier; Costes, Nicolas; Suaud-Chagny, Marie-Françoise; Brunelin, Jérome

2018-01-01

Abstract A single transcranial direct current stimulation (tDCS) session applied over the dorsolateral prefrontal cortex (DLFPC) can be associated with procognitive effects. Furthermore, repeated DLPFC tDCS sessions are under investigation as a new therapeutic tool for a range of neuropsychiatric conditions. A possible mechanism explaining such beneficial effects is a modulation of meso-cortico-limbic dopamine transmission. We explored the spatial and temporal neurobiological effects of bifrontal tDCS on subcortical dopamine transmission during and immediately after the stimulation. In a double blind sham-controlled study, 32 healthy subjects randomly received a single session of either active (20 min, 2 mA; n = 14) or sham (n = 18) tDCS during a dynamic positron emission tomography scan using [11C]raclopride binding. During the stimulation period, no significant effect of tDCS was observed. After the stimulation period, compared with sham tDCS, active tDCS induced a significant decrease in [11C]raclopride binding potential ratio in the striatum, suggesting an increase in extracellular dopamine in a part of the striatum involved in the reward–motivation network. The present study provides the first evidence that bifrontal tDCS induces neurotransmitter release in polysynaptic connected subcortical areas. Therefore, levels of dopamine activity and reactivity should be a new element to consider for a general hypothesis of brain modulation by bifrontal tDCS. PMID:29688276

Sex Mediates the Effects of High-Definition Transcranial Direct Current Stimulation on "Mind-Reading".

PubMed

Martin, A K; Huang, J; Hunold, A; Meinzer, M

2017-12-16

Sex differences in social cognitive ability are well established, including measures of Theory of Mind (ToM). The aim of this study was to investigate if sex mediates the effects of high-definition transcranial direct current stimulation (HD-tDCS) administered to a key hub of the social brain (i.e., the dorsomedial prefrontal cortex, dmPFC) on the Reading the Mind in the Eyes Test (RMET). Forty healthy young adults (18-35 years) were randomly allocated to receive either anodal or cathodal HD-tDCS in sham HD-tDCS controlled, double blind designs. In each of the two sessions, subjects completed the RMET. Anodal stimulation to the dmPFC increased accuracy on the RMET in females only. To assure regional specificity we performed a follow-up study stimulating the right temporoparietal junction and found no effect in either sex. The current study is the first to show improved performance on the RMET after tDCS to the dmPFC in females only. The polarity-specific effects and use of focal HD-tDCS provide evidence for sex-dependent differences in dmPFC function in relation to the RMET. Future studies using tDCS to study or improve ToM, need to consider sex. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Frontal Transcranial Direct Current Stimulation Induces Dopamine Release in the Ventral Striatum in Human.

PubMed

Fonteneau, Clara; Redoute, Jérome; Haesebaert, Frédéric; Le Bars, Didier; Costes, Nicolas; Suaud-Chagny, Marie-Françoise; Brunelin, Jérome

2018-07-01

A single transcranial direct current stimulation (tDCS) session applied over the dorsolateral prefrontal cortex (DLFPC) can be associated with procognitive effects. Furthermore, repeated DLPFC tDCS sessions are under investigation as a new therapeutic tool for a range of neuropsychiatric conditions. A possible mechanism explaining such beneficial effects is a modulation of meso-cortico-limbic dopamine transmission. We explored the spatial and temporal neurobiological effects of bifrontal tDCS on subcortical dopamine transmission during and immediately after the stimulation. In a double blind sham-controlled study, 32 healthy subjects randomly received a single session of either active (20 min, 2 mA; n = 14) or sham (n = 18) tDCS during a dynamic positron emission tomography scan using [11C]raclopride binding. During the stimulation period, no significant effect of tDCS was observed. After the stimulation period, compared with sham tDCS, active tDCS induced a significant decrease in [11C]raclopride binding potential ratio in the striatum, suggesting an increase in extracellular dopamine in a part of the striatum involved in the reward-motivation network. The present study provides the first evidence that bifrontal tDCS induces neurotransmitter release in polysynaptic connected subcortical areas. Therefore, levels of dopamine activity and reactivity should be a new element to consider for a general hypothesis of brain modulation by bifrontal tDCS.

Effects of transcranial direct current stimulation for treating depression: A modeling study.

PubMed

Csifcsák, Gábor; Boayue, Nya Mehnwolo; Puonti, Oula; Thielscher, Axel; Mittner, Matthias

2018-07-01

Transcranial direct current stimulation (tDCS) above the left dorsolateral prefrontal cortex (lDLPFC) has been widely used to improve symptoms of major depressive disorder (MDD). However, the effects of different stimulation protocols in the entire frontal lobe have not been investigated in a large sample including patient data. We used 38 head models created from structural magnetic resonance imaging data of 19 healthy adults and 19 MDD patients and applied computational modeling to simulate the spatial distribution of tDCS-induced electric fields (EFs) in 20 frontal regions. We evaluated effects of seven bipolar and two multi-electrode 4 × 1 tDCS protocols. For bipolar montages, EFs were of comparable strength in the lDLPFC and in the medial prefrontal cortex (MPFC). Depending on stimulation parameters, EF cortical maps varied to a considerable degree, but were found to be similar in controls and patients. 4 × 1 montages produced more localized, albeit weaker effects. White matter anisotropy was not modeled. The relationship between EF strength and clinical response to tDCS could not be evaluated. In addition to lDLPFC stimulation, excitability changes in the MPFC should also be considered as a potential mechanism underlying clinical efficacy of bipolar montages. MDD-associated anatomical variations are not likely to substantially influence current flow. Individual modeling of tDCS protocols can substantially improve cortical targeting. We make recommendations for future research to explicitly test the contribution of lDLPFC vs. MPFC stimulation to therapeutic outcomes of tDCS in this disorder. Copyright © 2018 Elsevier B.V. All rights reserved.

A clinical repetitive transcranial magnetic stimulation service in Australia: 6 years on.

PubMed

Galletly, Cherrie A; Clarke, Patrick; Carnell, Benjamin L; Gill, Shane

2015-11-01

There is considerable research evidence for the effectiveness of repetitive transcranial magnetic stimulation in the treatment of depression. However, there is little information about its acceptability and outcomes in clinical settings. This naturalistic study reports on a clinical repetitive transcranial magnetic stimulation service that has been running in Adelaide, South Australia (SA), for 6 years. During this time, 214 complete acute courses were provided to patients with treatment-resistant Major Depressive Disorder. Patients received either sequential bilateral or right unilateral repetitive transcranial magnetic stimulation treatment involving either 18 or 20 sessions given over 6 or 4 weeks respectively. Data included patient demographic details, duration of depression, and medication at the beginning of their repetitive transcranial magnetic stimulation course. The Hamilton Depression Rating Scale was used to assess response to repetitive transcranial magnetic stimulation. Of those undergoing a first-time acute treatment course of repetitive transcranial magnetic stimulation (N = 167), 28% achieved remission, while a further 12% met the criteria for a response to treatment. Most patients (N = 123, 77%) had previously been treated with five or more antidepressant medications, and 77 (47%) had previously received electroconvulsive therapy. Referral rates remained high over the 6 years, indicating acceptance of the treatment by referring psychiatrists. There were no significant adverse events, and the treatment was generally well tolerated. In all, 41 patients (25%) had a second course of repetitive transcranial magnetic stimulation and 6 (4%) patients had a third course; 21 patients subsequently received maintenance repetitive transcranial magnetic stimulation. This naturalistic study showed that repetitive transcranial magnetic stimulation was well accepted by both psychiatrists and patients, and has good efficacy and safety. Furthermore

Transcranial direct current stimulation (tDCS) to the supplementary motor area (SMA) influences performance on motor tasks.

PubMed

Hupfeld, K E; Ketcham, C J; Schneider, H D

2017-03-01

The supplementary motor area (SMA) is believed to be highly involved in the planning and execution of both simple and complex motor tasks. This study aimed to examine the role of the SMA in planning the movements required to complete reaction time, balance, and pegboard tasks using anodal transcranial direct current stimulation (tDCS), which passes a weak electrical current between two electrodes, in order to modulate neuronal activity. Twenty healthy adults were counterbalanced to receive either tDCS (experimental condition) or no tDCS (control condition) for 3 days. During administration of tDCS, participants performed a balance task significantly faster than controls. After tDCS, subjects significantly improved their simple and choice reaction time. These results demonstrate that the SMA is highly involved in planning and executing fine and gross motor skill tasks and that tDCS is an effective modality for increasing SMA-related performance on these tasks. The findings may be generalizable and therefore indicate implications for future interventions using tDCS as a therapeutic tool.

Electrified emotions: Modulatory effects of transcranial direct stimulation on negative emotional reactions to social exclusion.

PubMed

Riva, Paolo; Romero Lauro, Leonor J; Vergallito, Alessandra; DeWall, C Nathan; Bushman, Brad J

2015-01-01

Social exclusion, ostracism, and rejection can be emotionally painful because they thwart the need to belong. Building on studies suggesting that the right ventrolateral prefrontal cortex (rVLPFC) is associated with regulation of negative emotions, the present experiment tests the hypothesis that decreasing the cortical excitability of the rVLPFC may increase negative emotional reactions to social exclusion. Specifically, we applied cathodal transcranial direct current stimulation (tDCS) over the rVLPFC and predicted an increment of negative emotional reactions to social exclusion. In Study 1, participants were either socially excluded or included, while cathodal tDCS or sham stimulation was applied over the rVLPFC. Cathodal stimulation of rVLPFC boosted the typical negative emotional reaction caused by social exclusion. No effects emerged from participants in the inclusion condition. To test the specificity of tDCS effects over rVLPFC, in Study 2, participants were socially excluded and received cathodal tDCS or sham stimulation over a control region (i.e., the right posterior parietal cortex). No effects of tDCS stimulation were found. Our results showed that the rVLPFC is specifically involved in emotion regulation and suggest that cathodal stimulation can increase negative emotional responses to social exclusion.

Anodal Transcranial Direct Current Stimulation Reduces Psychophysically Measured Surround Suppression in the Human Visual Cortex

PubMed Central

Spiegel, Daniel P.; Hansen, Bruce C.; Byblow, Winston D.; Thompson, Benjamin

2012-01-01

Transcranial direct current stimulation (tDCS) is a safe, non-invasive technique for transiently modulating the balance of excitation and inhibition within the human brain. It has been reported that anodal tDCS can reduce both GABA mediated inhibition and GABA concentration within the human motor cortex. As GABA mediated inhibition is thought to be a key modulator of plasticity within the adult brain, these findings have broad implications for the future use of tDCS. It is important, therefore, to establish whether tDCS can exert similar effects within non-motor brain areas. The aim of this study was to assess whether anodal tDCS could reduce inhibitory interactions within the human visual cortex. Psychophysical measures of surround suppression were used as an index of inhibition within V1. Overlay suppression, which is thought to originate within the lateral geniculate nucleus (LGN), was also measured as a control. Anodal stimulation of the occipital poles significantly reduced psychophysical surround suppression, but had no effect on overlay suppression. This effect was specific to anodal stimulation as cathodal stimulation had no effect on either measure. These psychophysical results provide the first evidence for tDCS-induced reductions of intracortical inhibition within the human visual cortex. PMID:22563485

Transcranial direct current stimulation over Broca's region improves phonemic and semantic fluency in healthy individuals.

PubMed

Cattaneo, Z; Pisoni, A; Papagno, C

2011-06-02

Previous studies have demonstrated that transcranial direct current stimulation (tDCS) can be proficiently used to modulate attentional and cognitive functions. For instance, in the language domain there is evidence that tDCS can fasten picture naming in both healthy individuals and aphasic patients, or improve grammar learning. In this study, we investigated whether tDCS can be used to increase healthy subjects' performance in phonemic and semantic fluency tasks, that are typically used in clinical assessment of language. Ten healthy individuals performed a semantic and a phonemic fluency task following anodal tDCS applied over Broca's region. Each participant underwent a real and a sham tDCS session. Participants were found to produce more words following real anodal tDCS both in the phonemic and in the semantic fluency. Control experiments ascertained that this finding did not depend upon unspecific effects of tDCS over levels of general arousal or attention or upon participants' expectations. These data confirm the efficacy of tDCS in transiently improving language functions by showing that anodal stimulation of Broca's region can enhance verbal fluency. Implications of these results for the treatment of language functions in aphasia are considered. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Down-Regulation of Negative Emotional Processing by Transcranial Direct Current Stimulation: Effects of Personality Characteristics

PubMed Central

Peña-Gómez, Cleofé; Vidal-Piñeiro, Dídac; Clemente, Immaculada C.; Pascual-Leone, Álvaro; Bartrés-Faz, David

2011-01-01

Evidence from neuroimaging and electrophysiological studies indicates that the left dorsolateral prefrontal cortex (DLPFC) is a core region in emotional processing, particularly during down-regulation of negative emotional conditions. However, emotional regulation is a process subject to major inter-individual differences, some of which may be explained by personality traits. In the present study we used transcranial direct current stimulation (tDCS) over the left DLPFC to investigate whether transiently increasing the activity of this region resulted in changes in the ratings of positive, neutral and negative emotional pictures. Results revealed that anodal, but not cathodal, tDCS reduced the perceived degree of emotional valence for negative stimuli, possibly due to an enhancement of cognitive control of emotional expression. We also aimed to determine whether personality traits (extraversion and neuroticism) might condition the impact of tDCS. We found that individuals with higher scores on the introversion personality dimension were more permeable than extraverts to the modulatory effects of the stimulation. The present study underlines the role of the left DLPFC in emotional regulation, and stresses the importance of considering individual personality characteristics as a relevant variable, although replication is needed given the limited sample size of our study. PMID:21829522

[Transcranial direct current stimulation (tDCS) for depression: Results of nearly a decade of clinical research].

PubMed

Palm, U; Ayache, S S; Padberg, F; Lefaucheur, J-P

2016-02-01

Since 2006 transcranial direct current stimulation (tDCS) has been investigated in the treatment of depression. In this review, we discuss the implications and clinical perspectives that tDCS may have as a therapeutic tool in depression from the results reported in this domain. A comprehensive literature review has found nearly thirty articles - all in English - on this topic, corresponding to clinical studies, placebo-controlled or not, case reports and reviews. Several meta-analyses showed that the antidepressant effects of active tDCS are significant against placebo, but variable, mainly due to the heterogeneity of the patients included in the studies, for example regarding the resistance to antidepressant treatment. Specific recommendations for the use of tDCS in treating depression may not yet be available, but some elements of good practice can be highlighted. Of particular note is that anodal tDCS of the left prefrontal cortex at 2mA for 20 minutes per day has a potential therapeutic value without risk of significant side effects: tDCS offers safe conditions for clinical use in the treatment of depression. Copyright © 2015 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

No Change in Social Decision-Making Following Transcranial Direct Current Stimulation of the Right Temporoparietal Junction.

PubMed

Blair-West, Laura F; Hoy, Kate E; Hall, Phillip J; Fitzgerald, Paul B; Fitzgibbon, Bernadette M

2018-01-01

The right temporoparietal junction (rTPJ) is thought to play an important role in social cognition and pro-social decision-making. One way to explore this link is through the use of transcranial direct current stimulation (tDCS), a non-invasive brain stimulation method that is able to modulate cortical activity. The aim of this research was therefore to determine whether anodal tDCS to the rTPJ altered response to a social decision-making task. In this study, 34 healthy volunteers participated in a single-center, double-blinded, sham-controlled crossover design. Subjects received 20 min of active/sham anodal tDCS to the rTPJ before undertaking the Ultimatum Game (UG), a neuroeconomics paradigm in which participants are forced to choose between monetary reward and punishing an opponent's unfairness. Contrary to expectations, we found no significant difference between anodal and sham stimulation with regard to either the total number or reaction time of unfair offer rejections in the UG. This study draws attention to methodological issues in tDCS studies of the rTPJ, and highlights the complexity of social decision-making in the UG.

When anger leads to aggression: induction of relative left frontal cortical activity with transcranial direct current stimulation increases the anger–aggression relationship

PubMed Central

Hortensius, Ruud; Schutter, Dennis J. L. G.

2012-01-01

The relationship between anger and aggression is imperfect. Based on work on the neuroscience of anger, we predicted that anger associated with greater relative left frontal cortical activation would be more likely to result in aggression. To test this hypothesis, we combined transcranial direct current stimulation (tDCS) over the frontal cortex with interpersonal provocation. Participants received insulting feedback after 15 min of tDCS and were able to aggress by administering noise blasts to the insulting participant. Individuals who received tDCS to increase relative left frontal cortical activity behaved more aggressively when they were angry. No relation between anger and aggression was observed in the increase relative right frontal cortical activity or sham condition. These results concur with the motivational direction model of frontal asymmetry, in which left frontal activity is associated with anger. We propose that anger with approach motivational tendencies is more likely to result in aggression. PMID:21421731

Repetitive transcranial magnetic stimulation for hallucination in schizophrenia spectrum disorders: A meta-analysis.

PubMed

Zhang, Yingli; Liang, Wei; Yang, Shichang; Dai, Ping; Shen, Lijuan; Wang, Changhong

2013-10-05

This study assessed the efficacy and tolerability of repetitive transcranial magnetic stimulation for treatment of auditory hallucination of patients with schizophrenia spectrum disorders. Online literature retrieval was conducted using PubMed, ISI Web of Science, EMBASE, Medline and Cochrane Central Register of Controlled Trials databases from January 1985 to May 2012. Key words were "transcranial magnetic stimulation", "TMS", "repetitive transcranial magnetic stimulation", and "hallucination". Selected studies were randomized controlled trials assessing therapeutic efficacy of repetitive transcranial magnetic stimulation for hallucination in patients with schizophrenia spectrum disorders. Experimental intervention was low-frequency repetitive transcranial magnetic stimulation in left temporoparietal cortex for treatment of auditory hallucination in schizophrenia spectrum disorders. Control groups received sham stimulation. The primary outcome was total scores of Auditory Hallucinations Rating Scale, Auditory Hallucination Subscale of Psychotic Symptom Rating Scale, Positive and Negative Symptom Scale-Auditory Hallucination item, and Hallucination Change Scale. Secondary outcomes included response rate, global mental state, adverse effects and cognitive function. Seventeen studies addressing repetitive transcranial magnetic stimulation for treatment of schizophrenia spectrum disorders were screened, with controls receiving sham stimulation. All data were completely effective, involving 398 patients. Overall mean weighted effect size for repetitive transcranial magnetic stimulation versus sham stimulation was statistically significant (MD = -0.42, 95%CI: -0.64 to -0.20, P = 0.000 2). Patients receiving repetitive transcranial magnetic stimulation responded more frequently than sham stimulation (OR = 2.94, 95%CI: 1.39 to 6.24, P = 0.005). No significant differences were found between active repetitive transcranial magnetic stimulation and sham stimulation for

Pharmacological modulation of cortical excitability shifts induced by transcranial direct current stimulation in humans.

PubMed

Nitsche, M A; Fricke, K; Henschke, U; Schlitterlau, A; Liebetanz, D; Lang, N; Henning, S; Tergau, F; Paulus, W

2003-11-15

Transcranial direct current stimulation (tDCS) of the human motor cortex results in polarity-specific shifts of cortical excitability during and after stimulation. Anodal tDCS enhances and cathodal stimulation reduces excitability. Animal experiments have demonstrated that the effect of anodal tDCS is caused by neuronal depolarisation, while cathodal tDCS hyperpolarises cortical neurones. However, not much is known about the ion channels and receptors involved in these effects. Thus, the impact of the sodium channel blocker carbamazepine, the calcium channel blocker flunarizine and the NMDA receptor antagonist dextromethorphane on tDCS-elicited motor cortical excitability changes of healthy human subjects were tested. tDCS-protocols inducing excitability alterations (1) only during tDCS and (2) eliciting long-lasting after-effects were applied after drug administration. Carbamazepine selectively eliminated the excitability enhancement induced by anodal stimulation during and after tDCS. Flunarizine resulted in similar changes. Antagonising NMDA receptors did not alter current-generated excitability changes during a short stimulation, which elicits no after-effects, but prevented the induction of long-lasting after-effects independent of their direction. These results suggest that, like in other animals, cortical excitability shifts induced during tDCS in humans also depend on membrane polarisation, thus modulating the conductance of sodium and calcium channels. Moreover, they suggest that the after-effects may be NMDA receptor dependent. Since NMDA receptors are involved in neuroplastic changes, the results suggest a possible application of tDCS in the modulation or induction of these processes in a clinical setting. The selective elimination of tDCS-driven excitability enhancements by carbamazepine proposes a role for this drug in focussing the effects of cathodal tDCS, which may have important future clinical applications.

Pharmacological modulation of cortical excitability shifts induced by transcranial direct current stimulation in humans

PubMed Central

Nitsche, M A; Fricke, K; Henschke, U; Schlitterlau, A; Liebetanz, D; Lang, N; Henning, S; Tergau, F; Paulus, W

2003-01-01

Transcranial direct current stimulation (tDCS) of the human motor cortex results in polarity-specific shifts of cortical excitability during and after stimulation. Anodal tDCS enhances and cathodal stimulation reduces excitability. Animal experiments have demonstrated that the effect of anodal tDCS is caused by neuronal depolarisation, while cathodal tDCS hyperpolarises cortical neurones. However, not much is known about the ion channels and receptors involved in these effects. Thus, the impact of the sodium channel blocker carbamazepine, the calcium channel blocker flunarizine and the NMDA receptor antagonist dextromethorphane on tDCS-elicited motor cortical excitability changes of healthy human subjects were tested. tDCS-protocols inducing excitability alterations (1) only during tDCS and (2) eliciting long-lasting after-effects were applied after drug administration. Carbamazepine selectively eliminated the excitability enhancement induced by anodal stimulation during and after tDCS. Flunarizine resulted in similar changes. Antagonising NMDA receptors did not alter current-generated excitability changes during a short stimulation, which elicits no after-effects, but prevented the induction of long-lasting after-effects independent of their direction. These results suggest that, like in other animals, cortical excitability shifts induced during tDCS in humans also depend on membrane polarisation, thus modulating the conductance of sodium and calcium channels. Moreover, they suggest that the after-effects may be NMDA receptor dependent. Since NMDA receptors are involved in neuroplastic changes, the results suggest a possible application of tDCS in the modulation or induction of these processes in a clinical setting. The selective elimination of tDCS-driven excitability enhancements by carbamazepine proposes a role for this drug in focussing the effects of cathodal tDCS, which may have important future clinical applications. PMID:12949224

Transcranial magnetic stimulation--may be useful as a preoperative screen of motor tract function.

PubMed

Galloway, Gloria M; Dias, Brennan R; Brown, Judy L; Henry, Christina M; Brooks, David A; Buggie, Ed W

2013-08-01

Transcranial motor stimulation with noninvasive cortical surface stimulation, using a high-intensity magnetic field referred to as transcranial magnetic stimulation generally, is considered a nonpainful technique. In contrast, transcranial electric stimulation of the motor tracts typically cannot be done in unanesthesized patients. Intraoperative monitoring of motor tract function with transcranial electric stimulation is considered a standard practice in many institutions for patients during surgical procedures in which there is potential risk of motor tract impairment so that the risk of paraplegia or paraparesis can be reduced. Because transcranial electric stimulation cannot be typically done in the outpatient setting, transcranial magnetic stimulation may be able to provide a well-tolerated method for evaluation of the corticospinal motor tracts before surgery. One hundred fifty-five patients aged 5 to 20 years were evaluated preoperatively with single-stimulation nonrepetitive transcranial magnetic stimulation for preoperative assessment. The presence of responses to transcranial magnetic stimulation reliably predicted the presence of responses to transcranial electric stimulation intraoperatively. No complications occurred during the testing, and findings were correlated to the clinical history and used in the setup of the surgical monitoring.

Spatial and polarity precision of concentric high-definition transcranial direct current stimulation (HD-tDCS).

PubMed

Alam, Mahtab; Truong, Dennis Q; Khadka, Niranjan; Bikson, Marom

2016-06-21

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that applies low amplitude current via electrodes placed on the scalp. Rather than directly eliciting a neuronal response, tDCS is believed to modulate excitability-enhancing or suppressing neuronal activity in regions of the brain depending on the polarity of stimulation. The specificity of tDCS to any therapeutic application derives in part from how electrode configuration determines the brain regions that are stimulated. Conventional tDCS uses two relatively large pads (>25 cm(2)) whereas high-definition tDCS (HD-tDCS) uses arrays of smaller electrodes to enhance brain targeting. The 4  ×  1 concentric ring HD-tDCS (one center electrode surrounded by four returns) has been explored in application where focal targeting of cortex is desired. Here, we considered optimization of concentric ring HD-tDCS for targeting: the role of electrodes in the ring and the ring's diameter. Finite element models predicted cortical electric field generated during tDCS. High resolution MRIs were segmented into seven tissue/material masks of varying conductivities. Computer aided design (CAD) model of electrodes, gel, and sponge pads were incorporated into the segmentation. Volume meshes were generated and the Laplace equation ([Formula: see text] · (σ [Formula: see text] V)  =  0) was solved for cortical electric field, which was interpreted using physiological assumptions to correlate with stimulation and modulation. Cortical field intensity was predicted to increase with increasing ring diameter at the cost of focality while uni-directionality decreased. Additional surrounding ring electrodes increased uni-directionality while lowering cortical field intensity and increasing focality; though, this effect saturated and more than 4 surround electrode would not be justified. Using a range of concentric HD-tDCS montages, we showed that cortical region of influence can be

[Self-directed learning in nursing students with different background factors].

PubMed

Kao, Yu-Hsiu; Yu, Chu-Wei; Kuo, Shu-Yi; Kuang, I-Hsiu

2013-08-01

Fostering self-directed learning skills in nursing students may provide a foundation for improving the specialty knowledge of these nurses. This study examines the current status of nursing student self-directed learning behavior and explores how different background factors impact self-directed learning. This research design used a cross-sectional survey and convenience sampling. A total of 550 questionnaires were distributed to participants in enrolled in nursing programs at a 2-year nursing program at an institute of technology in northern Taiwan and a 4-year nursing program at an institute of technology in southern Taiwan. A convenience sampling was used to collect data, with 537 valid questionnaires used in data analysis. Results indicated that the self-directed learning and self-management of nursing students between 20-21 years old was significantly higher than those of students between 18-19 years old. Self-directed learning, desire of learning and self-control in 2-year nursing students were significantly higher than in 4-year and extension education department nursing student participants. Two-year nursing students had the highest self-management scores, followed by extension education department participants and 4-year nursing students. Finally, participants who associated highly with the nursing profession earned the highest self-directed total score, followed by those participants who associated generally and those who associated mildly. The results recommend that teachers at nursing institutes help students develop self-directed learning. Results also recommend teachers increase their students' association with the nursing specialty through understanding the impact of different background factors on self-directed learning.

A feasible repetitive transcranial magnetic stimulation clinical protocol in migraine prevention.

PubMed

Zardouz, Shawn; Shi, Lei; Leung, Albert

2016-01-01

This case series was conducted to determine the clinical feasibility of a repetitive transcranial magnetic stimulation protocol for the prevention of migraine (with and without aura). Five patients with migraines underwent five repetitive transcranial magnetic stimulation sessions separated in 1- to 2-week intervals for a period of 2 months at a single tertiary medical center. Repetitive transcranial magnetic stimulation was applied to the left motor cortex with 2000 pulses (20 trains with 1s inter-train interval) delivered per session, at a frequency of 10 Hz and 80% resting motor threshold. Pre- and post-treatment numerical rating pain scales were collected, and percent reductions in intensity, frequency, and duration were generated. An average decrease in 37.8%, 32.1%, and 31.2% were noted in the intensity, frequency, and duration of migraines post-repetitive transcranial magnetic stimulation, respectively. A mean decrease in 1.9±1.0 (numerical rating pain scale ± standard deviation; range: 0.4-2.8) in headache intensity scores was noted after the repetitive transcranial magnetic stimulation sessions. The tested repetitive transcranial magnetic stimulation protocol is a well-tolerated, safe, and effective method for migraine prevention.

Improved Cognitive Function After Transcranial, Light-Emitting Diode Treatments in Chronic, Traumatic Brain Injury: Two Case Reports

PubMed Central

Saltmarche, Anita; Krengel, Maxine H.; Hamblin, Michael R.; Knight, Jeffrey A.

2011-01-01

Abstract Objective: Two chronic, traumatic brain injury (TBI) cases, where cognition improved following treatment with red and near-infrared light-emitting diodes (LEDs), applied transcranially to forehead and scalp areas, are presented. Background: Significant benefits have been reported following application of transcranial, low-level laser therapy (LLLT) to humans with acute stroke and mice with acute TBI. These are the first case reports documenting improved cognitive function in chronic, TBI patients treated with transcranial LED. Methods: Treatments were applied bilaterally and to midline sagittal areas using LED cluster heads [2.1″ diameter, 61 diodes (9 × 633 nm, 52 × 870 nm); 12–15 mW per diode; total power: 500 mW; 22.2 mW/cm2; 13.3 J/cm2 at scalp (estimated 0.4 J/cm2 to cortex)]. Results: Seven years after closed-head TBI from a motor vehicle accident, Patient 1 began transcranial LED treatments. Pre-LED, her ability for sustained attention (computer work) lasted 20 min. After eight weekly LED treatments, her sustained attention time increased to 3 h. The patient performs nightly home treatments (5 years); if she stops treating for more than 2 weeks, she regresses. Patient 2 had a history of closed-head trauma (sports/military, and recent fall), and magnetic resonance imaging showed frontoparietal atrophy. Pre-LED, she was on medical disability for 5 months. After 4 months of nightly LED treatments at home, medical disability discontinued; she returned to working full-time as an executive consultant with an international technology consulting firm. Neuropsychological testing after 9 months of transcranial LED indicated significant improvement (+1, +2SD) in executive function (inhibition, inhibition accuracy) and memory, as well as reduction in post-traumatic stress disorder. If she stops treating for more than 1 week, she regresses. At the time of this report, both patients are continuing treatment. Conclusions: Transcranial

Effects of anodal transcranial direct current stimulation combined with virtual reality for improving gait in children with spastic diparetic cerebral palsy: a pilot, randomized, controlled, double-blind, clinical trial.

PubMed

Collange Grecco, Luanda André; de Almeida Carvalho Duarte, Natália; Mendonça, Mariana E; Galli, Manuela; Fregni, Felipe; Oliveira, Claudia Santos

2015-12-01

To compare the effects of anodal vs. sham transcranial direct current stimulation combined with virtual reality training for improving gait in children with cerebral palsy. A pilot, randomized, controlled, double-blind, clinical trial. Rehabilitation clinics. A total of 20 children with diparesis owing to cerebral palsy. The experimental group received anodal stimulation and the control group received sham stimulation over the primary motor cortex during virtual reality training. All patients underwent the same training programme involving a virtual reality (10 sessions). Evaluations were performed before and after the intervention as well as at the one-month follow-up and involved gait analysis, the Gross Motor Function Measure, the Pediatric Evaluation Disability Inventory and the determination of motor evoked potentials. The experimental group had a better performance regarding gait velocity (experimental group: 0.63 ±0.17 to 0.85 ±0.11 m/s; control group: 0.73 ±0.15 to 0.61 ±0.15 m/s), cadence (experimental group: 97.4 ±14.1 to 116.8 ±8.7 steps/minute; control group: 92.6 ±10.4 to 99.7 ±9.7 steps/minute), gross motor function (dimension D experimental group: 59.7 ±12.8 to 74.9 ±13.8; control group: 58.9 ±10.4 to 69.4 ±9.3; dimension E experimental group: 59.0 ±10.9 to 79.1 ±8.5; control group: 60.3 ±10.1 to 67.4 ±11.4) and independent mobility (experimental group: 34.3 ±5.9 to 43.8 ±75.3; control group: 34.4 ±8.3 to 37.7 ±7.7). Moreover, transcranial direct current stimulation led to a significant increase in motor evoked potential (experimental group: 1.4 ±0.7 to 2.6 ±0.4; control group: 1.3 ±0.6 to 1.6 ±0.4). These preliminary findings support the hypothesis that anodal transcranial direct current stimulation combined with virtual reality training could be a useful tool for improving gait in children with cerebral palsy. © The Author(s) 2015.

Transcranial route of brain targeted delivery of methadone in oil.

PubMed

Pathirana, W; Abhayawardhana, P; Kariyawasam, H; Ratnasooriya, W D

2009-05-01

The unique anatomical arrangement of blood vessels and sinuses in the human skull and the brain, the prevalence of a high density of skin appendages in the scalp, extracranial vessels of the scalp communicating with the brain via emissary veins and most importantly, the way that the scalp is used in Ayurvedic medical system in treating diseases associated with the brain show that a drug could be transcranially delivered and targeted to the brain through the scalp. The present study was to investigate by measuring the antinociceptive effect on rats whether the opioid analgesic methadone could be delivered and targeted to the brain by transcranial delivery route. A non aqueous solution of methadone base in sesame oil was used for the application on the scalp. Animal studies were carried out using six groups of male rats consisting of group 1, the oral control treated with distilled water 1 ml; group 2, the oral positive control treated with methadone hydrochloride solution 316.5 mug/ml; group 3, the negative control treated transcranially with the blank sesame oil 0.2 ml and three test groups 4, 5 and 6 treated with three different dose levels of the transcranial oil formulation of methadone base, 41.6 mug/0.2 ml, 104 mug/0.2 ml and 208 mug/0.2 ml, respectively. The antinociceptive effects were examined by subjecting the rats to the hot plate and tail flick tests. The two higher concentrations of the three transcranial methadone formulations yielded response vs time curves showing nearly equal maximum antinociceptive effects similar to that of the oral positive control. Maximum analgesic effect after transcranial administration was observed between 1st and 2nd h and declined up to 6th hour. The results indicate that the transcranial brain targeted delivery of methadone base in the form of an oil based non aqueous solution results in statistically significant antinociceptive effects under experimental conditions. Therefore, it is possible to deliver central nervous

Enhancing Warfighter Cognitive Abilities with Transcranial Magnetic Stimulation: A Feasibility Analysis

DTIC Science & Technology

2007-06-01

AFRL-HE-WP-TR-2007-0095 Enhancing Warfighter Cognitive Abilities with Transcranial Magnetic Stimulation : a Feasibility Analysis Jeremy T. Nelson...Abilities with Transcranial N/A Magnetic Stimulation : a Feasibility Analysis 5b. GRANTNUMBER N/A 5c. PROGRAM ELEMENT NUMBER 62202F 6. AUTHOR(S) 5d...feasibility of using transcranial magnetic stimulation (TMS) to enhance warfighter cognitive abilities. An extensive literature review was conducted

The application of sparse arrays in high frequency transcranial focused ultrasound therapy: A simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pajek, Daniel, E-mail: dpajek@sri.utoronto.ca; Hynynen, Kullervo

2013-12-15

Purpose: Transcranial focused ultrasound is an emerging therapeutic modality that can be used to perform noninvasive neurosurgical procedures. The current clinical transcranial phased array operates at 650 kHz, however the development of a higher frequency array would enable more precision, while reducing the risk of standing waves. However, the smaller wavelength and the skull's increased distortion at this frequency are problematic. It would require an order of magnitude more elements to create such an array. Random sparse arrays enable steering of a therapeutic array with fewer elements. However, the tradeoffs inherent in the use of sparsity in a transcranial phasedmore » array have not been systematically investigated and so the objective of this simulation study is to investigate the effect of sparsity on transcranial arrays at a frequency of 1.5 MHz that provides small focal spots for precise exposure control. Methods: Transcranial sonication simulations were conducted using a multilayer Rayleigh-Sommerfeld propagation model. Element size and element population were varied and the phased array's ability to steer was assessed. Results: The focal pressures decreased proportionally as elements were removed. However, off-focus hotspots were generated if a high degree of steering was attempted with very sparse arrays. A phased array consisting of 1588 elements 3 mm in size, a 10% population, was appropriate for steering up to 4 cm in all directions. However, a higher element population would be required if near-skull sonication is desired. Conclusions: This study demonstrated that the development of a sparse, hemispherical array at 1.5 MHz could enable more precision in therapies that utilize lower intensity sonications.« less

The effects of medication use in transcranial direct current stimulation: A brief review.

PubMed

McLaren, Molly E; Nissim, Nicole R; Woods, Adam J

There has been increased interest in the potential use of transcranial direct current stimulation (tDCS) as treatment for multiple conditions including depression, pain, and cognitive impairment. However, few studies account for the possible influence of comorbid medications when conducting tDCS research. This literature review was conducted to examine what is currently known about the impact of medications on tDCS, provide recommendations for future research practices, and highlight areas where more research is needed. Key terms were searched in PubMed and Web of Science to identify studies that examine the impact of medication on tDCS effects in adults. Relevant papers' reference lists were also reviewed for thoroughness. Studies examined the effects of medication on 1 mA tDCS delivered to M1 (motor) and orbit/supraorbital (SO) area. All studies measured the effects of tDCS via MEP TMS paradigm. Results of the literature review suggest multiple classes of medications, including sodium and calcium channel blockers, and medications that influence various neurotransmitter systems (GABA, dopamine, serotonin, etc.) may all impact tDCS effects on tissue excitability. Research to date suggests multiple classes of medications may impact tDCS effects. These results highlight the importance of documenting medication use in research subjects and carefully considering what types of medications should be allowed into tDCS trials. Many questions still remain regarding the exact mechanisms of action for tDCS and how various parameters (medication dosages, tDCS stimulation intensity, etc.) may further impact the effects of medications on tDCS. Copyright © 2017 Elsevier Inc. All rights reserved.

Temporal profile of functional visual rehabilitative outcomes modulated by transcranial direct current stimulation.

PubMed

Plow, Ela B; Obretenova, Souzana N; Jackson, Mary Lou; Merabet, Lotfi B

2012-07-01

We have previously reported that transcranial direct current stimulation (tDCS) delivered to the occipital cortex enhances visual functional recovery when combined with three months of computer-based rehabilitative training in patients with hemianopia. The principal objective of this study was to evaluate the temporal sequence of effects of tDCS on visual recovery as they appear over the course of training and across different indicators of visual function. Primary objective outcome measures were 1) shifts in visual field border and 2) stimulus detection accuracy within the affected hemifield. These were compared between patients randomized to either vision restoration therapy (VRT) combined with active tDCS or VRT paired with sham tDCS. Training comprised two half-hour sessions, three times a week for three months. Primary outcome measures were collected at baseline (pretest), monthly interim intervals, and at posttest (three months). As secondary outcome measures, contrast sensitivity and reading performance were collected at pretest and posttest time points only. Active tDCS combined with VRT accelerated the recovery of stimulus detection as between-group differences appeared within the first month of training. In contrast, a shift in the visual field border was only evident at posttest (after three months of training). tDCS did not affect contrast sensitivity or reading performance. These results suggest that tDCS may differentially affect the magnitude and sequence of visual recovery in a manner that is task specific to the type of visual rehabilitative training strategy employed. © 2012 International Neuromodulation Society.

Repeated transcranial direct current stimulation prevents abnormal behaviors associated with abstinence from chronic nicotine consumption.

PubMed

Pedron, Solène; Monnin, Julie; Haffen, Emmanuel; Sechter, Daniel; Van Waes, Vincent

2014-03-01

Successful available treatments to quit smoking remain scarce. Recently, the potential of transcranial direct current stimulation (tDCS) as a tool to reduce craving for nicotine has gained interest. However, there is no documented animal model to assess the neurobiological mechanisms of tDCS on addiction-related behaviors. To address this topic, we have developed a model of repeated tDCS in mice and used it to validate its effectiveness in relieving nicotine addiction. Anodal repeated tDCS was applied over the frontal cortex of Swiss female mice. The stimulation electrode (anode) was fixed directly onto the cranium, and the reference electrode was placed onto the ventral thorax. A 2 × 20 min/day stimulation paradigm for five consecutive days was used (0.2 mA). In the first study, we screened for behaviors altered by the stimulation. Second, we tested whether tDCS could alleviate abnormal behaviors associated with abstinence from nicotine consumption. In naive animals, repeated tDCS had antidepressant-like properties 3 weeks after the last stimulation, improved working memory, and decreased conditioned place preference for nicotine without affecting locomotor activity and anxiety-related behavior. Importantly, abnormal behaviors associated with chronic nicotine exposure (ie, depression-like behavior, increase in nicotine-induced place preference) were normalized by repeated tDCS. Our data show for the first time in an animal model that repeated tDCS is a promising, non-expensive clinical tool that could be used to reduce smoking craving and facilitate smoking cessation. Our animal model will be useful to investigate the mechanisms underlying the effects of tDCS on addiction and other psychiatric disorders.

Effects of vestibular rehabilitation combined with transcranial cerebellar direct current stimulation in patients with chronic dizziness: An exploratory study.

PubMed

Koganemaru, Satoko; Goto, Fumiyuki; Arai, Miki; Toshikuni, Keitaro; Hosoya, Makoto; Wakabayashi, Takeshi; Yamamoto, Nobuko; Minami, Shujiro; Ikeda, Satoshi; Ikoma, Katsunori; Mima, Tatsuya

Vestibular rehabilitation is useful to alleviate chronic dizziness in patients with vestibular dysfunction. It aims to induce neuronal plasticity in the central nervous system (especially in the cerebellum) to promote vestibular compensation. Transcranial cerebellar direct current stimulation (tcDCS) reportedly enhances cerebellar function. We investigated whether vestibular rehabilitation partially combined with tcDCS is superior to the use of rehabilitation alone for the alleviation of dizziness. Patients with chronic dizziness due to vestibular dysfunction received rehabilitation concurrently with either 20-min tcDCS or sham stimulation for 5 days. Pre- and post-intervention (at 1 month) dizziness handicap inventory (DHI) scores and psychometric and motor parameters were compared. Sixteen patients completed the study. DHI scores in the tcDCS group showed significant improvement over those in the sham group (Mann-Whitney U test, p = 0.033). Vestibular rehabilitation partially combined with tcDCS appears to be a promising approach. Copyright © 2017 Elsevier Inc. All rights reserved.

Transcranial Direct Current Stimulation Modulates Neuronal Activity and Learning in Pilot Training

PubMed Central

Choe, Jaehoon; Coffman, Brian A.; Bergstedt, Dylan T.; Ziegler, Matthias D.; Phillips, Matthew E.

2016-01-01

Skill acquisition requires distributed learning both within (online) and across (offline) days to consolidate experiences into newly learned abilities. In particular, piloting an aircraft requires skills developed from extensive training and practice. Here, we tested the hypothesis that transcranial direct current stimulation (tDCS) can modulate neuronal function to improve skill learning and performance during flight simulator training of aircraft landing procedures. Thirty-two right-handed participants consented to participate in four consecutive daily sessions of flight simulation training and received sham or anodal high-definition-tDCS to the right dorsolateral prefrontal cortex (DLPFC) or left motor cortex (M1) in a randomized, double-blind experiment. Continuous electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) were collected during flight simulation, n-back working memory, and resting-state assessments. tDCS of the right DLPFC increased midline-frontal theta-band activity in flight and n-back working memory training, confirming tDCS-related modulation of brain processes involved in executive function. This modulation corresponded to a significantly different online and offline learning rates for working memory accuracy and decreased inter-subject behavioral variability in flight and n-back tasks in the DLPFC stimulation group. Additionally, tDCS of left M1 increased parietal alpha power during flight tasks and tDCS to the right DLPFC increased midline frontal theta-band power during n-back and flight tasks. These results demonstrate a modulation of group variance in skill acquisition through an increasing in learned skill consistency in cognitive and real-world tasks with tDCS. Further, tDCS performance improvements corresponded to changes in electrophysiological and blood-oxygenation activity of the DLPFC and motor cortices, providing a stronger link between modulated neuronal function and behavior. PMID:26903841

Repetitive transcranial magnetic stimulation for hallucination in schizophrenia spectrum disorders: A meta-analysis

PubMed Central

Zhang, Yingli; Liang, Wei; Yang, Shichang; Dai, Ping; Shen, Lijuan; Wang, Changhong

2013-01-01

Objective: This study assessed the efficacy and tolerability of repetitive transcranial magnetic stimulation for treatment of auditory hallucination of patients with schizophrenia spectrum disorders. Data Sources: Online literature retrieval was conducted using PubMed, ISI Web of Science, EMBASE, Medline and Cochrane Central Register of Controlled Trials databases from January 1985 to May 2012. Key words were “transcranial magnetic stimulation”, “TMS”, “repetitive transcranial magnetic stimulation”, and “hallucination”. Study Selection: Selected studies were randomized controlled trials assessing therapeutic efficacy of repetitive transcranial magnetic stimulation for hallucination in patients with schizophrenia spectrum disorders. Experimental intervention was low-frequency repetitive transcranial magnetic stimulation in left temporoparietal cortex for treatment of auditory hallucination in schizophrenia spectrum disorders. Control groups received sham stimulation. Main Outcome Measures: The primary outcome was total scores of Auditory Hallucinations Rating Scale, Auditory Hallucination Subscale of Psychotic Symptom Rating Scale, Positive and Negative Symptom Scale-Auditory Hallucination item, and Hallucination Change Scale. Secondary outcomes included response rate, global mental state, adverse effects and cognitive function. Results: Seventeen studies addressing repetitive transcranial magnetic stimulation for treatment of schizophrenia spectrum disorders were screened, with controls receiving sham stimulation. All data were completely effective, involving 398 patients. Overall mean weighted effect size for repetitive transcranial magnetic stimulation versus sham stimulation was statistically significant (MD = –0.42, 95%CI: –0.64 to –0.20, P = 0.000 2). Patients receiving repetitive transcranial magnetic stimulation responded more frequently than sham stimulation (OR = 2.94, 95%CI: 1.39 to 6.24, P = 0.005). No significant differences were

Safety parameter considerations of anodal transcranial Direct Current Stimulation in rats.

PubMed

Jackson, Mark P; Truong, Dennis; Brownlow, Milene L; Wagner, Jessica A; McKinley, R Andy; Bikson, Marom; Jankord, Ryan

2017-08-01

A commonly referenced transcranial Direct Current Stimulation (tDCS) safety threshold derives from tDCS lesion studies in the rat and relies on electrode current density (and related electrode charge density) to support clinical guidelines. Concerns about the role of polarity (e.g. anodal tDCS), sub-lesion threshold injury (e.g. neuroinflammatory processes), and role of electrode montage across rodent and human studies support further investigation into animal models of tDCS safety. Thirty-two anesthetized rats received anodal tDCS between 0 and 5mA for 60min through one of three epicranial electrode montages. Tissue damage was evaluated using hemotoxylin and eosin (H&E) staining, Iba-1 immunohistochemistry, and computational brain current density modeling. Brain lesion occurred after anodal tDCS at and above 0.5mA using a 25.0mm 2 electrode (electrode current density: 20.0A/m 2 ). Lesion initially occurred using smaller 10.6mm 2 or 5.3mm 2 electrodes at 0.25mA (23.5A/m 2 ) and 0.5mA (94.2A/m 2 ), respectively. Histological damage was correlated with computational brain current density predictions. Changes in microglial phenotype occurred in higher stimulation groups. Lesions were observed using anodal tDCS at an electrode current density of 20.0A/m 2 , which is below the previously reported safety threshold of 142.9A/m 2 using cathodal tDCS. The lesion area is not simply predicted by electrode current density (and so not by charge density as duration was fixed); rather computational modeling suggests average brain current density as a better predictor for anodal tDCS. Nonetheless, under the assumption that rodent epicranial stimulation is a hypersensitive model, an electrode current density of 20.0A/m 2 represents a conservative threshold for clinical tDCS, which typically uses an electrode current density of 2A/m 2 when electrodes are placed on the skin (resulting in a lower brain current density). Copyright © 2017 Elsevier Inc. All rights reserved.

Sensorimotor Rhythm BCI with Simultaneous High Definition-Transcranial Direct Current Stimulation Alters Task Performance.

PubMed

Baxter, Bryan S; Edelman, Bradley J; Nesbitt, Nicholas; He, Bin

Transcranial direct current stimulation (tDCS) has been used to alter the excitability of neurons within the cerebral cortex. Improvements in motor learning have been found in multiple studies when tDCS was applied to the motor cortex before or during task learning. The motor cortex is also active during the performance of motor imagination, a cognitive task during which a person imagines, but does not execute, a movement. Motor imagery can be used with noninvasive brain computer interfaces (BCIs) to control virtual objects in up to three dimensions, but to master control of such devices requires long training times. To evaluate the effect of high-definition tDCS on the performance and underlying electrophysiology of motor imagery based BCI. We utilize high-definition tDCS to investigate the effect of stimulation on motor imagery-based BCI performance across and within sessions over multiple training days. We report a decreased time-to-hit with anodal stimulation both within and across sessions. We also found differing electrophysiological changes of the stimulated sensorimotor cortex during online BCI task performance for left vs. right trials. Cathodal stimulation led to a decrease in alpha and beta band power during task performance compared to sham stimulation for right hand imagination trials. These results suggest that unilateral tDCS over the sensorimotor motor cortex differentially affects cortical areas based on task specific neural activation. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Transcranial Direct Current Stimulation on Neural Networks in Young and Older Adults

PubMed

Martin, Andrew K; Meinzer, Marcus; Lindenberg, Robert; Sieg, Mira M; Nachtigall, Laura; Flöel, Agnes

2017-11-01

Transcranial direct current stimulation (tDCS) may be a viable tool to improve motor and cognitive function in advanced age. However, although a number of studies have demonstrated improved cognitive performance in older adults, other studies have failed to show restorative effects. The neural effects of beneficial stimulation response in both age groups is lacking. In the current study, tDCS was administered during simultaneous fMRI in 42 healthy young and older participants. Semantic word generation and motor speech baseline tasks were used to investigate behavioral and neural effects of uni- and bihemispheric motor cortex tDCS in a three-way, crossover, sham tDCS controlled design. Independent components analysis assessed differences in task-related activity between the two age groups and tDCS effects at the network level. We also explored whether laterality of language network organization was effected by tDCS. Behaviorally, both active tDCS conditions significantly improved semantic word retrieval performance in young and older adults and were comparable between groups and stimulation conditions. Network-level tDCS effects were identified in the ventral and dorsal anterior cingulate networks in the combined sample during semantic fluency and motor speech tasks. In addition, a shift toward enhanced left laterality was identified in the older adults for both active stimulation conditions. Thus, tDCS results in common network-level modulations and behavioral improvements for both age groups, with an additional effect of increasing left laterality in older adults.

Probing for hemispheric specialization for motor skill learning: a transcranial direct current stimulation study

PubMed Central

Schambra, Heidi M.; Abe, Mitsunari; Luckenbaugh, David A.; Reis, Janine; Krakauer, John W.

2011-01-01

Convergent findings point to a left-sided specialization for the representation of learned actions in right-handed humans, but it is unknown whether analogous hemispheric specialization exists for motor skill learning. In the present study, we explored this question by comparing the effects of anodal transcranial direct current stimulation (tDCS) over either left or right motor cortex (M1) on motor skill learning in either hand, using a tDCS montage to better isolate stimulation to one hemisphere. Results were compared with those previously found with a montage more commonly used in the field. Six groups trained for three sessions on a visually guided sequential pinch force modulation task with their right or left hand and received right M1, left M1, or sham tDCS. A linear mixed-model analysis for motor skill showed a significant main effect for stimulation group (left M1, right M1, sham) but not for hand (right, left) or their interaction. Left M1 tDCS induced significantly greater skill learning than sham when hand data were combined, a result consistent not only with the hypothesized left hemisphere specialization for motor skill learning but also with possible increased left M1 responsiveness to tDCS. The unihemispheric montage effect size was one-half that of the more common montage, and subsequent power analysis indicated that 75 subjects per group would be needed to detect differences seen with only 12 subjects with the customary bihemispheric montage. PMID:21613597

Transcranial direct current stimulation improves clinical symptoms in adolescents with attention deficit hyperactivity disorder.

PubMed

Soff, Cornelia; Sotnikova, Anna; Christiansen, Hanna; Becker, Katja; Siniatchkin, Michael

2017-01-01

Anodal transcranial direct current stimulation (tDCS) of the prefrontal cortex has repeatedly been shown to improve working memory. As patients with attention deficit hyperactivity disorder (ADHD) are characterized by both underactivation of the prefrontal cortex and deficits in working memory that correlate with clinical symptoms, it is hypothesized that the modulation of prefrontal activity with tDCS in patients with ADHD increases performance in working memory and reduces symptoms of ADHD. To test this hypothesis, fifteen adolescents with ADHD (12-16 years old, three girls and 12 boys) were treated according to the randomized, double-blinded, sham-controlled, crossover design with either 1 mA anodal tDCS over the left dorsolateral prefrontal cortex or with the sham protocol 5 days each with a 2 weeks pause between these conditions. Anodal tDCS caused a significant reduction in clinical symptoms of inattention and impulsivity in adolescents with ADHD compared to sham stimulation. The clinical effects were supported by a significant reduction in inattention and hyperactivity in a standardized working memory test (QbTest). The described effects were more pronounced 7 days after the end of stimulation, a fact which emphasizes the long-lasting clinical and neuropsychological changes after tDCS. This study provides the first evidence that tDCS may reduce symptoms of ADHD and improve neuropsychological functioning in adolescents and points on the potential of tDCS as a form of treatment for ADHD.

Transcranial Direct Current Stimulation Does Not Influence the Speed-Accuracy Tradeoff in Perceptual Decision-making: Evidence from Three Independent Studies.

PubMed

de Hollander, Gilles; Labruna, Ludovica; Sellaro, Roberta; Trutti, Anne; Colzato, Lorenza S; Ratcliff, Roger; Ivry, Richard B; Forstmann, Birte U

2016-09-01

In perceptual decision-making tasks, people balance the speed and accuracy with which they make their decisions by modulating a response threshold. Neuroimaging studies suggest that this speed-accuracy tradeoff is implemented in a corticobasal ganglia network that includes an important contribution from the pre-SMA. To test this hypothesis, we used anodal transcranial direct current stimulation (tDCS) to modulate neural activity in pre-SMA while participants performed a simple perceptual decision-making task. Participants viewed a pattern of moving dots and judged the direction of the global motion. In separate trials, they were cued to either respond quickly or accurately. We used the diffusion decision model to estimate the response threshold parameter, comparing conditions in which participants received sham or anodal tDCS. In three independent experiments, we failed to observe an influence of tDCS on the response threshold. Additional, exploratory analyses showed no influence of tDCS on the duration of nondecision processes or on the efficiency of information processing. Taken together, these findings provide a cautionary note, either concerning the causal role of pre-SMA in decision-making or on the utility of tDCS for modifying response caution in decision-making tasks.

Transcranial direct current stimulation (tDCS) in behavioral and food addiction: a systematic review of efficacy, technical, and methodological issues.

PubMed

Sauvaget, Anne; Trojak, Benoît; Bulteau, Samuel; Jiménez-Murcia, Susana; Fernández-Aranda, Fernando; Wolz, Ines; Menchón, José M; Achab, Sophia; Vanelle, Jean-Marie; Grall-Bronnec, Marie

2015-01-01

Behavioral addictions (BA) are complex disorders for which pharmacological and psychotherapeutic treatments have shown their limits. Non-invasive brain stimulation, among which transcranial direct current stimulation (tDCS), has opened up new perspectives in addiction treatment. The purpose of this work is to conduct a critical and systematic review of tDCS efficacy, and of technical and methodological considerations in the field of BA. A bibliographic search has been conducted on the Medline and ScienceDirect databases until December 2014, based on the following selection criteria: clinical studies on tDCS and BA (namely eating disorders, compulsive buying, Internet addiction, pathological gambling, sexual addiction, sports addiction, video games addiction). Study selection, data analysis, and reporting were conducted according to the PRISMA guidelines. Out of 402 potential articles, seven studies were selected. So far focusing essentially on abnormal eating, these studies suggest that tDCS (right prefrontal anode/left prefrontal cathode) reduces food craving induced by visual stimuli. Despite methodological and technical differences between studies, the results are promising. So far, only few studies of tDCS in BA have been conducted. New research is recommended on the use of tDCS in BA, other than eating disorders.

Transcranial magnetic and electrical stimulation compared: does TES activate intracortical neuronal circuits?

PubMed

Brocke, J; Irlbacher, K; Hauptmann, B; Voss, M; Brandt, S A

2005-12-01

To determine whether, and under which conditions, transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) can activate similar neuronal structures of the human motor cortex, as indicated by electromyographic recordings. Focal TMS was performed on three subjects inducing a postero-anterior directed current (p-a), TES with postero-anteriorly (p-a) and latero-medially (l-m) oriented electrodes. We analyzed the onset latencies and amplitudes (single-pulse) and intracortical inhibition and excitation (paired-pulse). TMS p-a and TES p-a produced muscle responses with the same onset latency, while TES l-m led to 1.4-1.9 ms shorter latencies. Paired-pulse TMS p-a and TES p-a induced inhibition at short inter-stimulus intervals (ISI) (maximum: 2-3 ms) and facilitation at longer ISIs (maximum: 10 ms). No inhibition but a strong facilitation was obtained from paired-pulse TES l-m (ISIs 1-5 ms). Our findings support the hypothesis, that current direction is the most relevant factor in determining the mode of activation for both TMS and TES: TMS p-a and TES p-a are likely to activate the corticospinal neurons indirectly. In contrast, TES l-m may preferentially activate the corticospinal fibres directly, distant of the neuronal body. TES is a suitable tool to induce intracortical inhibition and excitation.

High-definition transcranial direct-current stimulation of the right M1 further facilitates left M1 excitability during crossed facilitation.

PubMed

Cabibel, Vincent; Muthalib, Makii; Teo, Wei-Peng; Perrey, Stephane

2018-04-01

The crossed-facilitation (CF) effect refers to when motor-evoked potentials (MEPs) evoked in the relaxed muscles of one arm are facilitated by contraction of the opposite arm. The aim of this study was to determine whether high-definition transcranial direct-current stimulation (HD-tDCS) applied to the right primary motor cortex (M1) controlling the left contracting arm [50% maximum voluntary isometric contraction (MVIC)] would further facilitate CF toward the relaxed right arm. Seventeen healthy right-handed subjects participated in an anodal and cathodal or sham HD-tDCS session of the right M1 (2 mA for 20 min) separated by at least 48 h. Single-pulse transcranial magnetic stimulation (TMS) was used to elicit MEPs and cortical silent periods (CSPs) from the left M1 at baseline and 10 min into and after right M1 HD-tDCS. At baseline, compared with resting, CF (i.e., right arm resting, left arm 50% MVIC) increased left M1 MEP amplitudes (+97%) and decreased CSPs (-11%). The main novel finding was that right M1 HD-tDCS further increased left M1 excitability (+28.3%) and inhibition (+21%) from baseline levels during CF of the left M1, with no difference between anodal and cathodal HD-tDCS sessions. No modulation of CSP or MEP was observed during sham HD-tDCS sessions. Our findings suggest that CF of the left M1 combined with right M1 anodal or cathodal HD-tDCS further facilitated interhemispheric interactions during CF from the right M1 (contracting left arm) toward the left M1 (relaxed right arm), with effects on both excitatory and inhibitory processing. NEW & NOTEWORTHY This study shows modulation of the nonstimulated left M1 by right M1 HD-tDCS combined with crossed facilitation, which was probably achieved through modulation of interhemispheric interactions.

Semantic Feature Training in Combination with Transcranial Direct Current Stimulation (tDCS) for Progressive Anomia

PubMed Central

Hung, Jinyi; Bauer, Ashley; Grossman, Murray; Hamilton, Roy H.; Coslett, H. B.; Reilly, Jamie

2017-01-01

We examined the effectiveness of a 2-week regimen of a semantic feature training in combination with transcranial direct current stimulation (tDCS) for progressive naming impairment associated with primary progressive aphasia (N = 4) or early onset Alzheimer’s Disease (N = 1). Patients received a 2-week regimen (10 sessions) of anodal tDCS delivered over the left temporoparietal cortex while completing a language therapy that consisted of repeated naming and semantic feature generation. Therapy targets consisted of familiar people, household items, clothes, foods, places, hygiene implements, and activities. Untrained items from each semantic category provided item level controls. We analyzed naming accuracies at multiple timepoints (i.e., pre-, post-, 6-month follow-up) via a mixed effects logistic regression and individual differences in treatment responsiveness using a series of non-parametric McNemar tests. Patients showed advantages for naming trained over untrained items. These gains were evident immediately post tDCS. Trained items also showed a shallower rate of decline over 6-months relative to untrained items that showed continued progressive decline. Patients tolerated stimulation well, and sustained improvements in naming accuracy suggest that the current intervention approach is viable. Future implementation of a sham control condition will be crucial toward ascertaining whether neurostimulation and behavioral treatment act synergistically or alternatively whether treatment gains are exclusively attributable to either tDCS or the behavioral intervention. PMID:28559805

The impact of cerebellar transcranial direct current stimulation (tDCS) on learning fine-motor sequences

PubMed Central

Wu, Allan D.; Samra, Jasmine K.

2017-01-01

The cerebellum has been shown to be important for skill learning, including the learning of motor sequences. We investigated whether cerebellar transcranial direct current stimulation (tDCS) would enhance learning of fine motor sequences. Because the ability to generalize or transfer to novel task variations or circumstances is a crucial goal of real world training, we also examined the effect of tDCS on performance of novel sequences after training. In Study 1, participants received either anodal, cathodal or sham stimulation while simultaneously practising three eight-element key press sequences in a non-repeating, interleaved order. Immediately after sequence practice with concurrent tDCS, a transfer session was given in which participants practised three interleaved novel sequences. No stimulation was given during transfer. An inhibitory effect of cathodal tDCS was found during practice, such that the rate of learning was slowed in comparison to the anodal and sham groups. In Study 2, participants received anodal or sham stimulation and a 24 h delay was added between the practice and transfer sessions to reduce mental fatigue. Although this consolidation period benefitted subsequent transfer for both tDCS groups, anodal tDCS enhanced transfer performance. Together, these studies demonstrate polarity-specific effects on fine motor sequence learning and generalization. This article is part of the themed issue ‘New frontiers for statistical learning in the cognitive sciences’. PMID:27872369

The impact of cerebellar transcranial direct current stimulation (tDCS) on learning fine-motor sequences.

PubMed

Shimizu, Renee E; Wu, Allan D; Samra, Jasmine K; Knowlton, Barbara J

2017-01-05

The cerebellum has been shown to be important for skill learning, including the learning of motor sequences. We investigated whether cerebellar transcranial direct current stimulation (tDCS) would enhance learning of fine motor sequences. Because the ability to generalize or transfer to novel task variations or circumstances is a crucial goal of real world training, we also examined the effect of tDCS on performance of novel sequences after training. In Study 1, participants received either anodal, cathodal or sham stimulation while simultaneously practising three eight-element key press sequences in a non-repeating, interleaved order. Immediately after sequence practice with concurrent tDCS, a transfer session was given in which participants practised three interleaved novel sequences. No stimulation was given during transfer. An inhibitory effect of cathodal tDCS was found during practice, such that the rate of learning was slowed in comparison to the anodal and sham groups. In Study 2, participants received anodal or sham stimulation and a 24 h delay was added between the practice and transfer sessions to reduce mental fatigue. Although this consolidation period benefitted subsequent transfer for both tDCS groups, anodal tDCS enhanced transfer performance. Together, these studies demonstrate polarity-specific effects on fine motor sequence learning and generalization.This article is part of the themed issue 'New frontiers for statistical learning in the cognitive sciences'. © 2016 The Author(s).

A Protocol for the Use of Remotely-Supervised Transcranial Direct Current Stimulation (tDCS) in Multiple Sclerosis (MS).

PubMed

Kasschau, Margaret; Sherman, Kathleen; Haider, Lamia; Frontario, Ariana; Shaw, Michael; Datta, Abhishek; Bikson, Marom; Charvet, Leigh

2015-12-26

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that uses low amplitude direct currents to alter cortical excitability. With well-established safety and tolerability, tDCS has been found to have the potential to ameliorate symptoms such as depression and pain in a range of conditions as well as to enhance outcomes of cognitive and physical training. However, effects are cumulative, requiring treatments that can span weeks or months and frequent, repeated visits to the clinic. The cost in terms of time and travel is often prohibitive for many participants, and ultimately limits real-world access. Following guidelines for remote tDCS application, we propose a protocol that would allow remote (in-home) participation that uses specially-designed devices for supervised use with materials modified for patient use, and real-time monitoring through a telemedicine video conferencing platform. We have developed structured training procedures and clear, detailed instructional materials to allow for self- or proxy-administration while supervised remotely in real-time. The protocol is designed to have a series of checkpoints, addressing attendance and tolerability of the session, to be met in order to continue to the next step. The feasibility of this protocol was then piloted for clinical use in an open label study of remotely-supervised tDCS in multiple sclerosis (MS). This protocol can be widely used for clinical study of tDCS.

Slow oscillating transcranial direct current stimulation during non-rapid eye movement sleep improves behavioral inhibition in attention-deficit/hyperactivity disorder

PubMed Central

Munz, Manuel T.; Prehn-Kristensen, Alexander; Thielking, Frederieke; Mölle, Matthias; Göder, Robert; Baving, Lioba

2015-01-01

Background: Behavioral inhibition, which is a later-developing executive function (EF) and anatomically located in prefrontal areas, is impaired in attention-deficit and hyperactivity disorder (ADHD). While optimal EFs have been shown to depend on efficient sleep in healthy subjects, the impact of sleep problems, frequently reported in ADHD, remains elusive. Findings of macroscopic sleep changes in ADHD are inconsistent, but there is emerging evidence for distinct microscopic changes with a focus on prefrontal cortical regions and non-rapid eye movement (non-REM) slow-wave sleep. Recently, slow oscillations (SO) during non-REM sleep were found to be less functional and, as such, may be involved in sleep-dependent memory impairments in ADHD. Objective:By augmenting slow-wave power through bilateral, slow oscillating transcranial direct current stimulation (so-tDCS, frequency = 0.75 Hz) during non-REM sleep, we aimed to improve daytime behavioral inhibition in children with ADHD. Methods: Fourteen boys (10–14 years) diagnosed with ADHD were included. In a randomized, double-blind, cross-over design, patients received so-tDCS either in the first or in the second experimental sleep night. Inhibition control was assessed with a visuomotor go/no-go task. Intrinsic alertness was assessed with a simple stimulus response task. To control for visuomotor performance, motor memory was assessed with a finger sequence tapping task. Results: SO-power was enhanced during early non-REM sleep, accompanied by slowed reaction times and decreased standard deviations of reaction times, in the go/no-go task after so-tDCS. In contrast, intrinsic alertness, and motor memory performance were not improved by so-tDCS. Conclusion: Since behavioral inhibition but not intrinsic alertness or motor memory was improved by so-tDCS, our results suggest that lateral prefrontal slow oscillations during sleep might play a specific role for executive functioning in ADHD. PMID:26321911

Transcranial direct current stimulation of dorsolateral prefrontal cortex during encoding improves recall but not recognition memory

DOE PAGES

Leshikar, Eric D.; Leach, Ryan C.; McCurdy, Matthew P.; ...

2017-10-19

Prior work demonstrates that application of transcranial direct current stimulation (tDCS) improves memory. In this study, we investigated tDCS effects on face-name associative memory using both recall and recognition tests. Participants encoded face-name pairs under either active (1.5 mA) or sham (.1 mA) stimulation applied to the scalp adjacent to the left dorsolateral prefrontal cortex (dlPFC), an area known to support associative memory. Participants’ memory was then tested after study (day one) and then again after a 24-h delay (day two), to assess both immediate and delayed stimulation effects on memory. Results indicated that active relative to sham stimulation ledmore » to substantially improved recall (more than 50%) at both day one and day two. Recognition memory performance did not differ between stimulation groups at either time point. These results suggest that stimulation at encoding improves memory performance by enhancing memory for details that enable a rich recollective experience, but that these improvements are evident only under some testing conditions, especially those that rely on recollection. Altogether, stimulation of the dlPFC could have led to recall improvement through enhanced encoding from stimulation or from carryover effects of stimulation that influenced retrieval processes, or both.« less

Transcranial direct current stimulation of dorsolateral prefrontal cortex during encoding improves recall but not recognition memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leshikar, Eric D.; Leach, Ryan C.; McCurdy, Matthew P.

Prior work demonstrates that application of transcranial direct current stimulation (tDCS) improves memory. In this study, we investigated tDCS effects on face-name associative memory using both recall and recognition tests. Participants encoded face-name pairs under either active (1.5 mA) or sham (.1 mA) stimulation applied to the scalp adjacent to the left dorsolateral prefrontal cortex (dlPFC), an area known to support associative memory. Participants’ memory was then tested after study (day one) and then again after a 24-h delay (day two), to assess both immediate and delayed stimulation effects on memory. Results indicated that active relative to sham stimulation ledmore » to substantially improved recall (more than 50%) at both day one and day two. Recognition memory performance did not differ between stimulation groups at either time point. These results suggest that stimulation at encoding improves memory performance by enhancing memory for details that enable a rich recollective experience, but that these improvements are evident only under some testing conditions, especially those that rely on recollection. Altogether, stimulation of the dlPFC could have led to recall improvement through enhanced encoding from stimulation or from carryover effects of stimulation that influenced retrieval processes, or both.« less

Transcranial direct current stimulation and cognitive training in the rehabilitation of Alzheimer disease: A case study.

PubMed

Penolazzi, Barbara; Bergamaschi, Susanna; Pastore, Massimiliano; Villani, Daniele; Sartori, Giuseppe; Mondini, Sara

2015-01-01

In the present study we tested the cognitive effects of transcranial direct current stimulation (tDCS) in a case of probable Alzheimer disease (AD). The patient (male, 60 years, mild AD) underwent two cycles of treatments, separated by 2 months. In the first cycle, active stimulation (10 sessions, 2 mA for 20 min; anode over the left dorsolateral prefrontal cortex) was followed by computerised tasks (CTs) specifically chosen to engage the most impaired cognitive processes in the patient (tDCS+CT condition). In the second cycle, which was structured as the first, CTs were administered after placebo stimulation (sham+CT condition). Effects on cognitive performance were evaluated not only by the CTs, but also by neuropsychological tests assessing global cognitive functioning. Statistical analyses revealed that whereas the tDCS+CT condition had few effects on the CTs, it induced a stability of the patient's global cognitive functioning lasting approximately 3 months, which was not achieved when the patient underwent sham+CT condition. Therefore, the synergetic use of tDCS and CTs appeared to slow down the cognitive decline of our patient. This preliminary result, although in need of further confirmation, suggests the potentiality of tDCS as an adjuvant tool for cognitive rehabilitation in AD.

Measurement of Transcranial Distance During Head-Down Tilt Using Ultrasound

NASA Technical Reports Server (NTRS)

Torikoshi, Shigeyo; Ballard, R. E.; Watenpaugh, D. E.; Murthy, G.; Bowley, S.; Yost, W. T.; Hargens, Alan R.

1995-01-01

Exposure to microgravity probably elevates blood pressure and flow in the head which may increase intracranial volume (ICV) and pressure (ICP). Due to the slightly compliant nature of the cranium, any increase of ICP will increase ICV and transcranial distance. We used a noninvasive ultrasound technique to measure transcranial distance (frontal to occipital) during head-down tilt. Seven subjects (ages 26-53) underwent the following tilt angles: 90 deg. upright, 30 deg., 0 deg., -6 deg., -10 deg., -6 deg., 0 deg., 30 deg., and 90 deg. Each angle was maintained for 1 min. Ultrasound wave frequency was collected continuously and transcranial distance was calculated (Delta(x) = x(Delta)f/f, where x is path length and f is frequency of the wave) for each tilt angle. Frequency decreased from 503.687 kHz (90 deg. upright) to 502.619 kHz (-10 deg.). These frequencies translated to an increased transcranial distance of 0.403 mm. Although our data suggest a significant increase in transcranial distance during head-down tilt, this apparent increase may result, in part, from head-down tilt-induced subcutaneous edema or cutaneous blood volume elevation. In three subjects, when the above protocol was repeated with an ace bandage wrapped around the head to minimize such edema, the increased transcranial distance from 90 deg. to -10 deg. was reduced by 0.174 mm. Further development of the technique to quantify bone-to-bone expansion unconfounded by cutaneous fluid is necessary. Therefore, this ultrasound technique may provide measurements of changes in cranial dimensions during microgravity.

Transcranial magnetic stimulation and potential cortical and trigeminothalamic mechanisms in migraine

PubMed Central

Andreou, Anna P.; Holland, Philip R.; Akerman, Simon; Summ, Oliver; Fredrick, Joe

2016-01-01

Abstract A single pulse of transcranial magnetic stimulation has been shown to be effective for the acute treatment of migraine with and without aura. Here we aimed to investigate the potential mechanisms of action of transcranial magnetic stimulation, using a transcortical approach, in preclinical migraine models. We tested the susceptibility of cortical spreading depression, the experimental correlate of migraine aura, and further evaluated the response of spontaneous and evoked trigeminovascular activity of second order trigemontothalamic and third order thalamocortical neurons in rats. Single pulse transcranial magnetic stimulation significantly inhibited both mechanical and chemically-induced cortical spreading depression when administered immediately post-induction in rats, but not when administered preinduction, and when controlled by a sham stimulation. Additionally transcranial magnetic stimulation significantly inhibited the spontaneous and evoked firing rate of third order thalamocortical projection neurons, but not second order neurons in the trigeminocervical complex, suggesting a potential modulatory effect that may underlie its utility in migraine. In gyrencephalic cat cortices, when administered post-cortical spreading depression, transcranial magnetic stimulation blocked the propagation of cortical spreading depression in two of eight animals. These results are the first to demonstrate that cortical spreading depression can be blocked in vivo using single pulse transcranial magnetic stimulation and further highlight a novel thalamocortical modulatory capacity that may explain the efficacy of magnetic stimulation in the treatment of migraine with and without aura. PMID:27246325

Improving executive function using transcranial infrared laser stimulation

PubMed Central

Blanco, Nathaniel J.; Maddox, W. Todd; Gonzalez-Lima, F.

2015-01-01

Transcranial infrared laser stimulation is a new non-invasive form of low-level light therapy that may have a wide range of neuropsychological applications. It entails using low-power and high-energy density infrared light from lasers to increase metabolic energy. Preclinical work showed that this intervention can increase cortical metabolic energy, thereby improving frontal cortex-based memory function in rats. Barrett & Gonzalez-Lima (2013) discovered that transcranial laser stimulation can enhance sustained attention and short-term memory in humans. We extend this line of work to executive function. Specifically, we ask whether transcranial laser stimulation enhances performance in the Wisconsin Card Sorting Task (WCST) that is considered the gold-standard of executive function and is compromised in normal aging and a number of neuropsychological disorders. We used a laser of a specific wavelength (1064 nm) that photostimulates cytochrome oxidase—the enzyme catalyzing oxygen consumption for metabolic energy production. Increased cytochrome oxidase activity is considered the primary mechanism of action of this intervention. Participants who received laser treatment made fewer errors and showed improved set-shifting ability relative to placebo controls. These results suggest that transcranial laser stimulation improves executive function and may have exciting potential for treating or preventing deficits resulting from neuropsychological disorders or normal aging. PMID:26017772

Transcranial alternating current stimulation modulates auditory temporal resolution in elderly people.

PubMed

Baltus, Alina; Vosskuhl, Johannes; Boetzel, Cindy; Herrmann, Christoph Siegfried

2018-05-13

Recent research provides evidence for a functional role of brain oscillations for perception. For example, auditory temporal resolution seems to be linked to individual gamma frequency of auditory cortex. Individual gamma frequency not only correlates with performance in between-channel gap detection tasks but can be modulated via auditory transcranial alternating current stimulation. Modulation of individual gamma frequency is accompanied by an improvement in gap detection performance. Aging changes electrophysiological frequency components and sensory processing mechanisms. Therefore, we conducted a study to investigate the link between individual gamma frequency and gap detection performance in elderly people using auditory transcranial alternating current stimulation. In a within-subject design, twelve participants were electrically stimulated with two individualized transcranial alternating current stimulation frequencies: 3 Hz above their individual gamma frequency (experimental condition) and 4 Hz below their individual gamma frequency (control condition) while they were performing a between-channel gap detection task. As expected, individual gamma frequencies correlated significantly with gap detection performance at baseline and in the experimental condition, transcranial alternating current stimulation modulated gap detection performance. In the control condition, stimulation did not modulate gap detection performance. In addition, in elderly, the effect of transcranial alternating current stimulation on auditory temporal resolution seems to be dependent on endogenous frequencies in auditory cortex: elderlies with slower individual gamma frequencies and lower auditory temporal resolution profit from auditory transcranial alternating current stimulation and show increased gap detection performance during stimulation. Our results strongly suggest individualized transcranial alternating current stimulation protocols for successful modulation of performance

Counteracting Fatigue in Multiple Sclerosis with Right Parietal Anodal Transcranial Direct Current Stimulation.

PubMed

Hanken, Katrin; Bosse, Mona; Möhrke, Kim; Eling, Paul; Kastrup, Andreas; Antal, Andrea; Hildebrandt, Helmut

2016-01-01

Fatigue in multiple sclerosis (MS) patients appears to correlate with vigilance decrement as reflected in an increase in reaction time (RT) and errors with prolonged time-on-task. The aim of this study was to investigate whether anodal transcranial direct current stimulation (tDCS) over the right parietal or frontal cortex counteracts fatigue-associated vigilance decrement and subjective fatigue. In study I, a randomized double-blind placebo-controlled study, anodal tDCS (1.5 mA) was delivered to the right parietal cortex or the right frontal cortex of 52 healthy participants during the first 20 min of a 40-min lasting visual vigilance task. Study II, also a randomized double-blind placebo-controlled study, investigated the effect of anodal tDCS (1.5 mA) over the right parietal cortex in 46 MS patients experiencing cognitive fatigue. tDCS was delivered for 20 min before patients performed a 20-min lasting visual vigilance task. Study I showed that right parietal stimulation, but not right frontal stimulation, counteracts the increase in RT associated with vigilance decrement. Hence, only right parietal stimulation was applied to the MS patients in study II. Stimulation had a significant effect on vigilance decrement in mildly to moderately cognitively fatigued MS patients. Vigilance testing significantly increased the feeling of fatigue independent of stimulation. Anodal tDCS over the right parietal cortex can counteract the increase in RTs during vigilance performance, but not the increase in subjective fatigue. This finding is compatible with our model of fatigue in MS, suggesting a dissociation between the feeling and the behavioral characteristics of fatigue.

Transcranial direct current stimulation improves isometric time to exhaustion of the knee extensors.

PubMed

Angius, L; Pageaux, B; Hopker, J; Marcora, S M; Mauger, A R

2016-12-17

Transcranial direct current stimulation (tDCS) can increase cortical excitability of a targeted brain area, which may affect endurance exercise performance. However, optimal electrode placement for tDCS remains unclear. We tested the effect of two different tDCS electrode montages for improving exercise performance. Nine subjects underwent a control (CON), placebo (SHAM) and two different tDCS montage sessions in a randomized design. In one tDCS session, the anodal electrode was placed over the left motor cortex and the cathodal on contralateral forehead (HEAD), while for the other montage the anodal electrode was placed over the left motor cortex and cathodal electrode above the shoulder (SHOULDER). tDCS was delivered for 10min at 2.0mA, after which participants performed an isometric time to exhaustion (TTE) test of the right knee extensors. Peripheral and central neuromuscular parameters were assessed at baseline, after tDCS application and after TTE. Heart rate (HR), ratings of perceived exertion (RPE), and leg muscle exercise-induced muscle pain (PAIN) were monitored during the TTE. TTE was longer and RPE lower in the SHOULDER condition (P<0.05). Central and peripheral parameters, and HR and PAIN did not present any differences between conditions after tDCS stimulation (P>0.05). In all conditions maximal voluntary contraction (MVC) significantly decreased after the TTE (P<0.05) while motor-evoked potential area (MEP) increased after TTE (P<0.05). These findings demonstrate that SHOULDER montage is more effective than HEAD montage to improve endurance performance, likely through avoiding the negative effects of the cathode on excitability. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Basic and functional effects of transcranial Electrical Stimulation (tES)-An introduction.

PubMed

Yavari, Fatemeh; Jamil, Asif; Mosayebi Samani, Mohsen; Vidor, Liliane Pinto; Nitsche, Michael A

2018-02-01

Non-invasive brain stimulation (NIBS) has been gaining increased popularity in human neuroscience research during the last years. Among the emerging NIBS tools is transcranial electrical stimulation (tES), whose main modalities are transcranial direct, and alternating current stimulation (tDCS, tACS). In tES, a small current (usually less than 3mA) is delivered through the scalp. Depending on its shape, density, and duration, the applied current induces acute or long-lasting effects on excitability and activity of cerebral regions, and brain networks. tES is increasingly applied in different domains to (a) explore human brain physiology with regard to plasticity, and brain oscillations, (b) explore the impact of brain physiology on cognitive processes, and (c) treat clinical symptoms in neurological and psychiatric diseases. In this review, we give a broad overview of the main mechanisms and applications of these brain stimulation tools. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transcranial magnetic stimulation and potential cortical and trigeminothalamic mechanisms in migraine.

PubMed

Andreou, Anna P; Holland, Philip R; Akerman, Simon; Summ, Oliver; Fredrick, Joe; Goadsby, Peter J

2016-07-01

A single pulse of transcranial magnetic stimulation has been shown to be effective for the acute treatment of migraine with and without aura. Here we aimed to investigate the potential mechanisms of action of transcranial magnetic stimulation, using a transcortical approach, in preclinical migraine models. We tested the susceptibility of cortical spreading depression, the experimental correlate of migraine aura, and further evaluated the response of spontaneous and evoked trigeminovascular activity of second order trigemontothalamic and third order thalamocortical neurons in rats. Single pulse transcranial magnetic stimulation significantly inhibited both mechanical and chemically-induced cortical spreading depression when administered immediately post-induction in rats, but not when administered preinduction, and when controlled by a sham stimulation. Additionally transcranial magnetic stimulation significantly inhibited the spontaneous and evoked firing rate of third order thalamocortical projection neurons, but not second order neurons in the trigeminocervical complex, suggesting a potential modulatory effect that may underlie its utility in migraine. In gyrencephalic cat cortices, when administered post-cortical spreading depression, transcranial magnetic stimulation blocked the propagation of cortical spreading depression in two of eight animals. These results are the first to demonstrate that cortical spreading depression can be blocked in vivo using single pulse transcranial magnetic stimulation and further highlight a novel thalamocortical modulatory capacity that may explain the efficacy of magnetic stimulation in the treatment of migraine with and without aura. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.

Real-time 3-D contrast-enhanced transcranial ultrasound and aberration correction.

PubMed

Ivancevich, Nikolas M; Pinton, Gianmarco F; Nicoletto, Heather A; Bennett, Ellen; Laskowitz, Daniel T; Smith, Stephen W

2008-09-01

Contrast-enhanced (CE) transcranial ultrasound (US) and reconstructed 3-D transcranial ultrasound have shown advantages over traditional methods in a variety of cerebrovascular diseases. We present the results from a novel ultrasound technique, namely real-time 3-D contrast-enhanced transcranial ultrasound. Using real-time 3-D (RT3D) ultrasound and microbubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and nine via the suboccipital window and report our detection rates for the major cerebral vessels. In 71% of subjects, both of our observers identified the ipsilateral circle of Willis from the temporal window, and in 59% we imaged the entire circle of Willis. From the suboccipital window, both observers detected the entire vertebrobasilar circulation in 22% of subjects, and in 44%, the basilar artery. After performing phase aberration correction on one subject, we were able to increase the diagnostic value of the scan, detecting a vessel not present in the uncorrected scan. These preliminary results suggest that RT3D CE transcranial US and RT3D CE transcranial US with phase aberration correction have the potential to greatly impact the field of neurosonology.

Real-Time 3D Contrast-Enhanced Transcranial Ultrasound and Aberration Correction

PubMed Central

Ivancevich, Nikolas M.; Pinton, Gianmarco F.; Nicoletto, Heather A.; Bennett, Ellen; Laskowitz, Daniel T.; Smith, Stephen W.

2008-01-01

Contrast-enhanced (CE) transcranial ultrasound (US) and reconstructed 3D transcranial ultrasound have shown advantages over traditional methods in a variety of cerebrovascular diseases. We present the results from a novel ultrasound technique, namely real-time 3D contrast-enhanced transcranial ultrasound. Using real-time 3D (RT3D) ultrasound and micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 71% of subjects, both of our observers identified the ipsilateral circle of Willis from the temporal window, and in 59% we imaged the entire circle of Willis. From the sub-occipital window, both observers detected the entire vertebrobasilar circulation in 22% of subjects, and in 44% the basilar artery. After performing phase aberration correction on one subject, we were able to increase the diagnostic value of the scan, detecting a vessel not present in the uncorrected scan. These preliminary results suggest that RT3D CE transcranial US and RT3D CE transcranial US with phase aberration correction have the potential to greatly impact the field of neurosonology. PMID:18395321

Physiological processes non-linearly affect electrophysiological recordings during transcranial electric stimulation.

PubMed

Noury, Nima; Hipp, Joerg F; Siegel, Markus

2016-10-15

Transcranial electric stimulation (tES) is a promising tool to non-invasively manipulate neuronal activity in the human brain. Several studies have shown behavioral effects of tES, but stimulation artifacts complicate the simultaneous investigation of neural activity with EEG or MEG. Here, we first show for EEG and MEG, that contrary to previous assumptions, artifacts do not simply reflect stimulation currents, but that heartbeat and respiration non-linearly modulate stimulation artifacts. These modulations occur irrespective of the stimulation frequency, i.e. during both transcranial alternating and direct current stimulations (tACS and tDCS). Second, we show that, although at first sight previously employed artifact rejection methods may seem to remove artifacts, data are still contaminated by non-linear stimulation artifacts. Because of their complex nature and dependence on the subjects' physiological state, these artifacts are prone to be mistaken as neural entrainment. In sum, our results uncover non-linear tES artifacts, show that current techniques fail to fully remove them, and pave the way for new artifact rejection methods. Copyright © 2016 Elsevier Inc. All rights reserved.

Using Transcranial Magnetic Stimulation to Evaluate the Motor Pathways After an Intraoperative Spinal Cord Injury and to Predict the Recovery of Intraoperative Transcranial Electrical Motor Evoked Potentials: A Case Report.

PubMed

Grover, Helen J; Thornton, Rachel; Lutchman, Lennel N; Blake, Julian C

2016-06-01

The authors report a case of unilateral loss of intraoperative transcranial electrical motor evoked potentials (TES MEP) associated with a spinal cord injury during scoliosis correction and the subsequent use of extraoperative transcranial magnetic stimulation to monitor the recovery of spinal cord function. The authors demonstrate the absence of TES MEPs and absent transcranial magnetic stimulation responses in the immediate postoperative period, and document the partial recovery of transcranial magnetic stimulation responses, which corresponded to partial recovery of TES MEPs. Intraoperative TES MEPs were enhanced using spatial facilitation technique, which enabled the patient to undergo further surgery to stabilize the spine and correct her scoliosis. This case report supports evidence of the use of extraoperative transcranial magnetic stimulation to predict the presence of intraoperative TES responses and demonstrates the usefulness of spatial facilitation to monitor TES MEPs in a patient with a preexisting spinal cord injury.

Laser scattering by transcranial rat brain illumination

NASA Astrophysics Data System (ADS)

Sousa, Marcelo V. P.; Prates, Renato; Kato, Ilka T.; Sabino, Caetano P.; Suzuki, Luis C.; Ribeiro, Martha S.; Yoshimura, Elisabeth M.

2012-06-01

Due to the great number of applications of Low-Level-Laser-Therapy (LLLT) in Central Nervous System (CNS), the study of light penetration through skull and distribution in the brain becomes extremely important. The aim is to analyze the possibility of precise illumination of deep regions of the rat brain, measure the penetration and distribution of red (λ = 660 nm) and Near Infra-Red (NIR) (λ = 808 nm) diode laser light and compare optical properties of brain structures. The head of the animal (Rattus Novergicus) was epilated and divided by a sagittal cut, 2.3 mm away from mid plane. This section of rat's head was illuminated with red and NIR lasers in points above three anatomical structures: hippocampus, cerebellum and frontal cortex. A high resolution camera, perpendicularly positioned, was used to obtain images of the brain structures. Profiles of scattered intensities in the laser direction were obtained from the images. There is a peak in the scattered light profile corresponding to the skin layer. The bone layer gives rise to a valley in the profile indicating low scattering coefficient, or frontal scattering. Another peak in the region related to the brain is an indication of high scattering coefficient (μs) for this tissue. This work corroborates the use of transcranial LLLT in studies with rats which are subjected to models of CNS diseases. The outcomes of this study point to the possibility of transcranial LLLT in humans for a large number of diseases.

Intensity, Duration, and Location of High-Definition Transcranial Direct Current Stimulation for Tinnitus Relief.

PubMed

Shekhawat, Giriraj Singh; Sundram, Frederick; Bikson, Marom; Truong, Dennis; De Ridder, Dirk; Stinear, Cathy M; Welch, David; Searchfield, Grant D

2016-05-01

Tinnitus is the perception of a phantom sound. The aim of this study was to compare current intensity (center anode 1 mA and 2 mA), duration (10 minutes and 20 minutes), and location (left temporoparietal area [LTA] and dorsolateral prefrontal cortex [DLPFC]) using 4 × 1 high-definition transcranial direct current stimulation (HD-tDCS) for tinnitus reduction. Twenty-seven participants with chronic tinnitus (>2 years) and mean age of 53.5 years underwent 2 sessions of HD-tDCS of the LTA and DLPFC in a randomized order with a 1 week gap between site of stimulation. During each session, a combination of 4 different settings were used in increasing dose (1 mA, 10 minutes; 1 mA, 20 minutes; 2 mA, 10 minutes; and 2 mA, 20 minutes). The impact of different settings on tinnitus loudness and annoyance was documented. Twenty-one participants (77.78%) reported a minimum of 1 point reduction on tinnitus loudness or annoyance scales. There were significant changes in loudness and annoyance for duration of stimulation,F(1, 26) = 10.08,P< .005, and current intensity,F(1, 26) = 14.24,P= .001. There was no interaction between the location, intensity, and duration of stimulation. Higher intensity (2 mA) and longer duration (20 minutes) of stimulation were more effective. A current intensity of 2 mA for 20-minute duration was the most effective setting used for tinnitus relief. The stimulation of the LTA and DLPFC were equally effective for suppressing tinnitus loudness and annoyance. © The Author(s) 2015.

Delayed enhancement of multitasking performance: Effects of anodal transcranial direct current stimulation on the prefrontal cortex.

PubMed

Hsu, Wan-Yu; Zanto, Theodore P; Anguera, Joaquin A; Lin, Yung-Yang; Gazzaley, Adam

2015-08-01

The dorsolateral prefrontal cortex (DLPFC) has been proposed to play an important role in neural processes that underlie multitasking performance. However, this claim is underexplored in terms of direct causal evidence. The current study aimed to delineate the causal involvement of the DLPFC during multitasking by modulating neural activity with transcranial direct current stimulation (tDCS) prior to engagement in a demanding multitasking paradigm. The study is a single-blind, crossover, sham-controlled experiment. Anodal tDCS or sham tDCS was applied over left DLPFC in forty-one healthy young adults (aged 18-35 years) immediately before they engaged in a 3-D video game designed to assess multitasking performance. Participants were separated into three subgroups: real-sham (i.e., real tDCS in the first session, followed by sham tDCS in the second session 1 h later), sham-real (sham tDCS first session, real tDCS second session), and sham-sham (sham tDCS in both sessions). The real-sham group showed enhanced multitasking performance and decreased multitasking cost during the second session, compared to first session, suggesting delayed cognitive benefits of tDCS. Interestingly, performance benefits were observed only for multitasking and not on a single-task version of the game. No significant changes were found between the first and second sessions for either the sham-real or the sham-sham groups. These results suggest a causal role of left prefrontal cortex in facilitating the simultaneous performance of more than one task, or multitasking. Moreover, these findings reveal that anodal tDCS may have delayed benefits that reflect an enhanced rate of learning. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improving executive function using transcranial infrared laser stimulation.

PubMed

Blanco, Nathaniel J; Maddox, W Todd; Gonzalez-Lima, Francisco

2017-03-01

Transcranial infrared laser stimulation is a new non-invasive form of low-level light therapy that may have a wide range of neuropsychological applications. It entails using low-power and high-energy-density infrared light from lasers to increase metabolic energy. Preclinical work showed that this intervention can increase cortical metabolic energy, thereby improving frontal cortex-based memory function in rats. Barrett and Gonzalez-Lima (2013, Neuroscience, 230, 13) discovered that transcranial laser stimulation can enhance sustained attention and short-term memory in humans. We extend this line of work to executive function. Specifically, we ask whether transcranial laser stimulation enhances performance in the Wisconsin Card Sorting Task that is considered the gold standard of executive function and is compromised in normal ageing and a number of neuropsychological disorders. We used a laser of a specific wavelength (1,064 nm) that photostimulates cytochrome oxidase - the enzyme catalysing oxygen consumption for metabolic energy production. Increased cytochrome oxidase activity is considered the primary mechanism of action of this intervention. Participants who received laser treatment made fewer errors and showed improved set-shifting ability relative to placebo controls. These results suggest that transcranial laser stimulation improves executive function and may have exciting potential for treating or preventing deficits resulting from neuropsychological disorders or normal ageing. © 2015 The British Psychological Society.

Comparison of Three Non-Invasive Transcranial Electrical Stimulation Methods for Increasing Cortical Excitability.

PubMed

Inukai, Yasuto; Saito, Kei; Sasaki, Ryoki; Tsuiki, Shota; Miyaguchi, Shota; Kojima, Sho; Masaki, Mitsuhiro; Otsuru, Naofumi; Onishi, Hideaki

2016-01-01

Transcranial direct current stimulation (tDCS) is a representative non-invasive brain stimulation method (NIBS). tDCS increases cortical excitability not only in healthy individuals, but also in stroke patients where it contributes to motor function improvement. Recently, two additional types of transcranial electrical stimulation (tES) methods have been introduced that may also prove beneficial for stimulating cortical excitability; these are transcranial random noise stimulation (tRNS) and transcranial alternating current stimulation (tACS). However, comparison of tDCS with tRNS and tACS, in terms of efficacy in cortical excitability alteration, has not been reported thus far. We compared the efficacy of the three different tES methods for increasing cortical excitability using the same subject population and same current intensity. Fifteen healthy subjects participated in this study. Similar stimulation patterns (1.0 mA and 10 min) were used for the three conditions of stimulation (tDCS, tRNS, and tACS). Cortical excitability was explored via single-pulse TMS elicited motor evoked potentials (MEPs). Compared with pre-measurements, MEPs significantly increased with tDCS, tACS, and tRNS ( p < 0.05). Compared with sham measurements, significant increases in MEPs were also observed with tRNS and tACS ( p < 0.05), but not with tDCS. In addition, a significant correlation of the mean stimulation effect was observed between tRNS and tACS ( p = 0.019, r = 0.598). tRNS induced a significant increase in MEP compared with the Pre or Sham at all time points. tRNS resulted in the largest significant increase in MEPs. These findings suggest that tRNS is the most effective tES method and should be considered as part of a treatment plan for improving motor function in stroke patients.

Transcranial electrical stimulation over visual cortex evokes phosphenes with a retinal origin.

PubMed

Kar, Kohitij; Krekelberg, Bart

2012-10-01

Transcranial electrical stimulation (tES) is a promising therapeutic tool for a range of neurological diseases. Understanding how the small currents used in tES spread across the scalp and penetrate the brain will be important for the rational design of tES therapies. Alternating currents applied transcranially above visual cortex induce the perception of flashes of light (phosphenes). This makes the visual system a useful model to study tES. One hypothesis is that tES generates phosphenes by direct stimulation of the cortex underneath the transcranial electrode. Here, we provide evidence for the alternative hypothesis that phosphenes are generated in the retina by current spread from the occipital electrode. Building on the existing literature, we first confirm that phosphenes are induced at lower currents when electrodes are placed farther away from visual cortex and closer to the eye. Second, we explain the temporal frequency tuning of phosphenes based on the well-known response properties of primate retinal ganglion cells. Third, we show that there is no difference in the time it takes to evoke phosphenes in the retina or by stimulation above visual cortex. Together, these findings suggest that phosphenes induced by tES over visual cortex originate in the retina. From this, we infer that tES currents spread well beyond the area of stimulation and are unlikely to lead to focal neural activation. Novel stimulation protocols that optimize current distributions are needed to overcome these limitations of tES.

After-effects of anodal transcranial direct current stimulation on the excitability of the motor cortex in rats.

PubMed

Koo, Ho; Kim, Min Sun; Han, Sang Who; Paulus, Walter; Nitche, Michael A; Kim, Yun-Hee; Kim, Hyoung-Ihl; Ko, Sung-Hwa; Shin, Yong-Il

2016-09-21

Transcranial direct current stimulation (tDCS) is increasingly seen as a useful tool for noninvasive cortical neuromodulation. A number of studies in humans have shown that when tDCS is applied to the motor cortex it can modulate cortical excitability. It is especially interesting to note that when applied with sufficient duration and intensity, tDCS can enable long-lasting neuroplastic effects. However, the mechanism by which tDCS exerts its effects on the cortex is not fully understood. We investigated the effects of anodal tDCS under urethane anesthesia on field potentials in in vivo rats. These were measured on the skull over the right motor cortex of rats immediately after stimulating the left corpus callosum. Evoked field potentials in the motor cortex were gradually increased for more than one hour after anodal tDCS. To induce these long-lasting effects, a sufficient duration of stimulation (20 minutes or more) was found to may be required rather than high stimulation intensity. We propose that anodal tDCS with a sufficient duration of stimulation may modulate transcallosal plasticity.

Differential sensory cortical involvement in auditory and visual sensorimotor temporal recalibration: Evidence from transcranial direct current stimulation (tDCS).

PubMed

Aytemür, Ali; Almeida, Nathalia; Lee, Kwang-Hyuk

2017-02-01

Adaptation to delayed sensory feedback following an action produces a subjective time compression between the action and the feedback (temporal recalibration effect, TRE). TRE is important for sensory delay compensation to maintain a relationship between causally related events. It is unclear whether TRE is a sensory modality-specific phenomenon. In 3 experiments employing a sensorimotor synchronization task, we investigated this question using cathodal transcranial direct-current stimulation (tDCS). We found that cathodal tDCS over the visual cortex, and to a lesser extent over the auditory cortex, produced decreased visual TRE. However, both auditory and visual cortex tDCS did not produce any measurable effects on auditory TRE. Our study revealed different nature of TRE in auditory and visual domains. Visual-motor TRE, which is more variable than auditory TRE, is a sensory modality-specific phenomenon, modulated by the auditory cortex. The robustness of auditory-motor TRE, unaffected by tDCS, suggests the dominance of the auditory system in temporal processing, by providing a frame of reference in the realignment of sensorimotor timing signals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Wearable functional near infrared spectroscopy (fNIRS) and transcranial direct current stimulation (tDCS): expanding vistas for neurocognitive augmentation

PubMed Central

McKendrick, Ryan; Parasuraman, Raja; Ayaz, Hasan

2015-01-01

Contemporary studies with transcranial direct current stimulation (tDCS) provide a growing base of evidence for enhancing cognition through the non-invasive delivery of weak electric currents to the brain. The main effect of tDCS is to modulate cortical excitability depending on the polarity of the applied current. However, the underlying mechanism of neuromodulation is not well understood. A new generation of functional near infrared spectroscopy (fNIRS) systems is described that are miniaturized, portable, and include wearable sensors. These developments provide an opportunity to couple fNIRS with tDCS, consistent with a neuroergonomics approach for joint neuroimaging and neurostimulation investigations of cognition in complex tasks and in naturalistic conditions. The effects of tDCS on complex task performance and the use of fNIRS for monitoring cognitive workload during task performance are described. Also explained is how fNIRS + tDCS can be used simultaneously for assessing spatial working memory. Mobile optical brain imaging is a promising neuroimaging tool that has the potential to complement tDCS for realistic applications in natural settings. PMID:25805976

Transcranial direct current stimulation (tDCS) in behavioral and food addiction: a systematic review of efficacy, technical, and methodological issues

PubMed Central

Sauvaget, Anne; Trojak, Benoît; Bulteau, Samuel; Jiménez-Murcia, Susana; Fernández-Aranda, Fernando; Wolz, Ines; Menchón, José M.; Achab, Sophia; Vanelle, Jean-Marie; Grall-Bronnec, Marie

2015-01-01

Objectives: Behavioral addictions (BA) are complex disorders for which pharmacological and psychotherapeutic treatments have shown their limits. Non-invasive brain stimulation, among which transcranial direct current stimulation (tDCS), has opened up new perspectives in addiction treatment. The purpose of this work is to conduct a critical and systematic review of tDCS efficacy, and of technical and methodological considerations in the field of BA. Methods: A bibliographic search has been conducted on the Medline and ScienceDirect databases until December 2014, based on the following selection criteria: clinical studies on tDCS and BA (namely eating disorders, compulsive buying, Internet addiction, pathological gambling, sexual addiction, sports addiction, video games addiction). Study selection, data analysis, and reporting were conducted according to the PRISMA guidelines. Results: Out of 402 potential articles, seven studies were selected. So far focusing essentially on abnormal eating, these studies suggest that tDCS (right prefrontal anode/left prefrontal cathode) reduces food craving induced by visual stimuli. Conclusions: Despite methodological and technical differences between studies, the results are promising. So far, only few studies of tDCS in BA have been conducted. New research is recommended on the use of tDCS in BA, other than eating disorders. PMID:26500478

Single-Session Transcranial Direct Current Stimulation Temporarily Improves Symptoms, Mood, and Self-Regulatory Control in Bulimia Nervosa: A Randomised Controlled Trial

PubMed Central

Kekic, Maria; McClelland, Jessica; Bartholdy, Savani; Boysen, Elena; Musiat, Peter; Dalton, Bethan; Tiza, Meyzi; David, Anthony S.; Campbell, Iain C.; Schmidt, Ulrike

2017-01-01

Background Evidence suggests that pathological eating behaviours in bulimia nervosa (BN) are underpinned by alterations in reward processing and self-regulatory control, and by functional changes in neurocircuitry encompassing the dorsolateral prefrontal cortex (DLPFC). Manipulation of this region with transcranial direct current stimulation (tDCS) may therefore alleviate symptoms of the disorder. Objective This double-blind sham-controlled proof-of-principle trial investigated the effects of bilateral tDCS over the DLPFC in adults with BN. Methods Thirty-nine participants (two males) received three sessions of tDCS in a randomised and counterbalanced order: anode right/cathode left (AR/CL), anode left/cathode right (AL/CR), and sham. A battery of psychological/neurocognitive measures was completed before and after each session and the frequency of bulimic behaviours during the following 24-hours was recorded. Results AR/CL tDCS reduced eating disorder cognitions (indexed by the Mizes Eating Disorder Cognitions Questionnaire-Revised) when compared to AL/CR and sham tDCS. Both active conditions suppressed the self-reported urge to binge-eat and increased self-regulatory control during a temporal discounting task. Compared to sham stimulation, mood (assessed with the Profile of Mood States) improved after AR/CL but not AL/CR tDCS. Lastly, the three tDCS sessions had comparable effects on the wanting/liking of food and on bulimic behaviours during the 24 hours post-stimulation. Conclusions These data suggest that single-session tDCS transiently improves symptoms of BN. They also help to elucidate possible mechanisms of action and highlight the importance of selecting the optimal electrode montage. Multi-session trials are needed to determine whether tDCS has potential for development as a treatment for adult BN. PMID:28121991

Effects of transcranial direct current stimulation (tDCS) on behaviour and electrophysiology of language production.

PubMed

Wirth, Miranka; Rahman, Rasha Abdel; Kuenecke, Janina; Koenig, Thomas; Horn, Helge; Sommer, Werner; Dierks, Thomas

2011-12-01

Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left dorsal prefrontal cortex (DPFC) has been shown to improve language production. The present study examined neurophysiological underpinnings of this effect. In a single-blinded within-subject design, we traced effects of A-tDCS compared to sham stimulation over the left DPFC using electrophysiological and behavioural correlates during overt picture naming. Online effects were examined during A-tDCS by employing the semantic interference (SI-)Effect - a marker that denotes the functional integrity of the language system. The behavioural SI-Effect was found to be reduced, whereas the electrophysiological SI-Effect was enhanced over left compared to right temporal scalp-electrode sites. This modulation is suggested to reflect a superior tuning of neural responses within language-related generators. After -(offline) effects of A-tDCS were detected in the delta frequency band, a marker of neural inhibition. After A-tDCS there was a reduction in delta activity during picture naming and the resting state, interpreted to indicate neural disinhibition. Together, these findings demonstrate electrophysiological modulations induced by A-tDCS of the left DPFC. They suggest that A-tDCS is capable of enhancing neural processes during and after application. The present functional and oscillatory neural markers could detect positive effects of prefrontal A-tDCS, which could be of use in the neuro-rehabilitation of frontal language functions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Impact of antipsychotic medication on transcranial direct current stimulation (tDCS) effects in schizophrenia patients.

PubMed

Agarwal, Sri Mahavir; Bose, Anushree; Shivakumar, Venkataram; Narayanaswamy, Janardhanan C; Chhabra, Harleen; Kalmady, Sunil V; Varambally, Shivarama; Nitsche, Michael A; Venkatasubramanian, Ganesan; Gangadhar, Bangalore N

2016-01-30

Transcranial direct current stimulation (tDCS) has generated interest as a treatment modality for schizophrenia. Dopamine, a critical pathogenetic link in schizophrenia, is also known to influence tDCS effects. We evaluated the influence of antipsychotic drug type (as defined by dopamine D2 receptor affinity) on the impact of tDCS in schizophrenia. DSM-IV-TR-diagnosed schizophrenia patients [N=36] with persistent auditory hallucinations despite adequate antipsychotic treatment were administered add-on tDCS. Patients were divided into three groups based on the antipsychotic's affinity to D2 receptors. An auditory hallucinations score (AHS) was measured using the auditory hallucinations subscale of the Psychotic Symptom Rating Scales (PSYRATS). Add-on tDCS resulted in a significant reduction inAHS. Antipsychotic drug type had a significant effect on AHS reduction. Patients treated with high affinity antipsychotics showed significantly lesser improvement compared to patients on low affinity antipsychotics or a mixture of the two. Furthermore, a significant sex-by-group interaction occurred; type of medication had an impact on tDCS effects only in women. Improvement differences could be due to the larger availability of the dopamine receptor system in patients taking antipsychotics with low D2 affinity. Sex-specific differences suggest potential estrogen-mediated effects. This study reports a first-time observation on the clinical utility of antipsychotic drug type in predicting tDCS effects in schizophrenia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Comparison of visual field training for hemianopia with active versus sham transcranial direct cortical stimulation.

PubMed

Plow, Ela B; Obretenova, Souzana N; Fregni, Felipe; Pascual-Leone, Alvaro; Merabet, Lotfi B

2012-01-01

Vision Restoration Therapy (VRT) aims to improve visual field function by systematically training regions of residual vision associated with the activity of suboptimal firing neurons within the occipital cortex. Transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability. Assess the possible efficacy of tDCS combined with VRT. The authors conducted a randomized, double-blind, demonstration-of-concept pilot study where participants were assigned to either VRT and tDCS or VRT and sham. The anode was placed over the occipital pole to target both affected and unaffected lobes. One hour training sessions were carried out 3 times per week for 3 months in a laboratory. Outcome measures included objective and subjective changes in visual field, recording of visual fixation performance, and vision-related activities of daily living (ADLs) and quality of life (QOL). Although 12 participants were enrolled, only 8 could be analyzed. The VRT and tDCS group demonstrated significantly greater expansion in visual field and improvement on ADLs compared with the VRT and sham group. Contrary to expectations, subjective perception of visual field change was greater in the VRT and sham group. QOL did not change for either group. The observed changes in visual field were unrelated to compensatory eye movements, as shown with fixation monitoring. The combination of occipital cortical tDCS with visual field rehabilitation appears to enhance visual functional outcomes compared with visual rehabilitation alone. TDCS may enhance inherent mechanisms of plasticity associated with training.

Effects of transcranial direct current stimulation of primary somatosensory cortex on vibrotactile detection and discrimination

PubMed Central

Labbé, Sara; Meftah, El-Mehdi

2016-01-01

Anodal transcranial direct current stimulation (a-tDCS) of primary somatosensory cortex (S1) has been shown to enhance tactile spatial acuity, but there is little information as to the underlying neuronal mechanisms. We examined vibrotactile perception on the distal phalanx of the middle finger before, during, and after contralateral S1 tDCS [a-, cathodal (c)-, and sham (s)-tDCS]. The experiments tested our shift-gain hypothesis, which predicted that a-tDCS would decrease vibrotactile detection and discrimination thresholds (leftward shift of the stimulus-response function with increased gain/slope) relative to s-tDCS, whereas c-tDCS would have the opposite effects (relative to s-tDCS). The results showed that weak a-tDCS (1 mA, 20 min) led to a reduction in both vibrotactile detection and discrimination thresholds to 73–76% of baseline during the application of the stimulation in subjects categorized as responders. These effects persisted after the end of a-tDCS but were absent 30 min later. Most, but not all, subjects showed a decrease in threshold (8/12 for detection; 9/12 for discrimination). Intersubject variability was explained by a ceiling effect in the discrimination task. c-tDCS had no significant effect on either detection or discrimination threshold. Taken together, our results supported our shift-gain hypothesis for a-tDCS but not c-tDCS. PMID:26864757

Transcranial direct current stimulation improves word retrieval in healthy and nonfluent aphasic subjects.

PubMed

Fiori, Valentina; Coccia, Michela; Marinelli, Chiara V; Vecchi, Veronica; Bonifazi, Silvia; Ceravolo, M Gabriella; Provinciali, Leandro; Tomaiuolo, Francesco; Marangolo, Paola

2011-09-01

A number of studies have shown that modulating cortical activity by means of transcranial direct current stimulation (tDCS) affects performances of both healthy and brain-damaged subjects. In this study, we investigated the potential of tDCS to enhance associative verbal learning in 10 healthy individuals and to improve word retrieval deficits in three patients with stroke-induced aphasia. In healthy individuals, tDCS (20 min, 1 mA) was applied over Wernicke's area (position CP5 of the International 10-20 EEG System) while they learned 20 new "words" (legal nonwords arbitrarily assigned to 20 different pictures). The healthy subjects participated in a randomized counterbalanced double-blind procedure in which they were subjected to one session of anodic tDCS over left Wernicke's area, one sham session over this location and one session of anodic tDCS stimulating the right occipito-parietal area. Each experimental session was performed during a different week (over three consecutive weeks) with 6 days of intersession interval. Over 2 weeks, three aphasic subjects participated in a randomized double-blind experiment involving intensive language training for their anomic difficulties in two tDCS conditions. Each subject participated in five consecutive daily sessions of anodic tDCS (20 min, 1 mA) and sham stimulation over Wernicke's area while they performed a picture-naming task. By the end of each week, anodic tDCS had significantly improved their accuracy on the picture-naming task. Both normal subjects and aphasic patients also had shorter naming latencies during anodic tDCS than during sham condition. At two follow-ups (1 and 3 weeks after the end of treatment), performed only in two aphasic subjects, response accuracy and reaction times were still significantly better in the anodic than in the sham condition, suggesting a long-term effect on recovery of their anomic disturbances.

Response variability of different anodal transcranial direct current stimulation intensities across multiple sessions.

PubMed

Ammann, Claudia; Lindquist, Martin A; Celnik, Pablo A

It is well known that transcranial direct current stimulation (tDCS) is capable of modulating corticomotor excitability. However, a source of growing concern has been the observed inter- and intra-individual variability of tDCS-responses. Recent studies have assessed whether individuals respond in a predictable manner across repeated sessions of anodal tDCS (atDCS). The findings of these investigations have been inconsistent, and their methods have some limitations (i.e. lack of sham condition or testing only one tDCS intensity). To study inter- and intra-individual variability of atDCS effects at two different intensities on primary motor cortex (M1) excitability. Twelve subjects participated in a crossover study testing 7-min atDCS over M1 in three separate conditions (2 mA, 1 mA, sham) each repeated three times separated by 48 h. Motor evoked potentials were recorded before and after stimulation (up to 30min). Time of testing was maintained consistent within participants. To estimate the reliability of tDCS effects across sessions, we calculated the Intra-class Correlation Coefficient (ICC). AtDCS at 2 mA, but not 1 mA, significantly increased cortical excitability at the group level in all sessions. The overall ICC revealed fair to high reliability of tDCS effects for multiple sessions. Given that the distribution of responses showed important variability in the sham condition, we established a Sham Variability-Based Threshold to classify responses and to track individual changes across sessions. Using this threshold an intra-individual consistent response pattern was then observed only for the 2 mA condition. 2 mA anodal tDCS results in consistent intra- and inter-individual increases of M1 excitability. Copyright © 2017 Elsevier Inc. All rights reserved.

Dosage Considerations for Transcranial Direct Current Stimulation in Children: A Computational Modeling Study

PubMed Central

Kessler, Sudha Kilaru; Minhas, Preet; Woods, Adam J.; Rosen, Alyssa; Gorman, Casey; Bikson, Marom

2013-01-01

Transcranial direct current stimulation (tDCS) is being widely investigated in adults as a therapeutic modality for brain disorders involving abnormal cortical excitability or disordered network activity. Interest is also growing in studying tDCS in children. Limited empirical studies in children suggest that tDCS is well tolerated and may have a similar safety profile as in adults. However, in electrotherapy as in pharmacotherapy, dose selection in children requires special attention, and simple extrapolation from adult studies may be inadequate. Critical aspects of dose adjustment include 1) differences in neurophysiology and disease, and 2) variation in brain electric fields for a specified dose due to gross anatomical differences between children and adults. In this study, we used high-resolution MRI derived finite element modeling simulations of two healthy children, ages 8 years and 12 years, and three healthy adults with varying head size to compare differences in electric field intensity and distribution. Multiple conventional and high-definition tDCS montages were tested. Our results suggest that on average, children will be exposed to higher peak electrical fields for a given applied current intensity than adults, but there is likely to be overlap between adults with smaller head size and children. In addition, exposure is montage specific. Variations in peak electrical fields were seen between the two pediatric models, despite comparable head size, suggesting that the relationship between neuroanatomic factors and bioavailable current dose is not trivial. In conclusion, caution is advised in using higher tDCS doses in children until 1) further modeling studies in a larger group shed light on the range of exposure possible by applied dose and age and 2) further studies correlate bioavailable dose estimates from modeling studies with empirically tested physiologic effects, such as modulation of motor evoked potentials after stimulation. PMID:24086698

Modulating oscillatory brain activity correlates of behavioral inhibition using transcranial direct current stimulation.

PubMed

Jacobson, Liron; Ezra, Adi; Berger, Uri; Lavidor, Michal

2012-05-01

Studies have mainly documented behavioral changes induced by transcranial direct current stimulation (tDCS), but recently cortical modulations of tDCS have also been investigated. Our previous work revealed behavioral inhibition modulation by anodal tDCS over the right inferior frontal gyrus (rIFG); however, the electrophysiological correlates underlying this stimulation montage have yet to be established. The current work aimed to evaluate the distribution of neuronal oscillations changes following anodal tDCS over rIFG coupled with cathodal tDCS over left orbitofrontal cortex (lOFC) using spectral power analysis. Healthy subjects underwent sham and real tDCS (15 min, 1.5 mA, anodal rIFG; cathodal lOFC) stimulation conditions in a single-blind, placebo-controlled cross-over trial. Following tDCS session, resting EEG recordings were collected during 15 min. Analysis showed a significant and selective diminution of the power of theta band. The theta diminution was observed in the rIFG area (represented the anode electrode), and was not found in the lOFC area (represented the cathode electrode). A significant effect was observed only in the theta but not in other bands. These results are the first demonstration of modulating oscillatory activity as measured by EEG with tDCS over rIFG in general, and documenting theta band reduction with this montage in particular. Our results may explain the improvement in behavioral inhibition reported in our previous work, and although this study was conducted with healthy subjects, the findings suggest that tDCS may also modulate electrophysiological changes among ADHD patients, where decreasing theta activity is the target of neuro-feedback methods aimed to improve cognitive control. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Change in Mean Frequency of Resting-State Electroencephalography after Transcranial Direct Current Stimulation

PubMed Central

Boonstra, Tjeerd W.; Nikolin, Stevan; Meisener, Ann-Christin; Martin, Donel M.; Loo, Colleen K.

2016-01-01

Transcranial direct current stimulation (tDCS) is proposed as a tool to investigate cognitive functioning in healthy people and as a treatment for various neuropathological disorders. However, the underlying cortical mechanisms remain poorly understood. We aim to investigate whether resting-state electroencephalography (EEG) can be used to monitor the effects of tDCS on cortical activity. To this end we tested whether the spectral content of ongoing EEG activity is significantly different after a single session of active tDCS compared to sham stimulation. Twenty participants were tested in a sham-controlled, randomized, crossover design. Resting-state EEG was acquired before, during and after active tDCS to the left dorsolateral prefrontal cortex (15 min of 2 mA tDCS) and sham stimulation. Electrodes with a diameter of 3.14 cm2 were used for EEG and tDCS. Partial least squares (PLS) analysis was used to examine differences in power spectral density (PSD) and the EEG mean frequency to quantify the slowing of EEG activity after stimulation. PLS revealed a significant increase in spectral power at frequencies below 15 Hz and a decrease at frequencies above 15 Hz after active tDCS (P = 0.001). The EEG mean frequency was significantly reduced after both active tDCS (P < 0.0005) and sham tDCS (P = 0.001), though the decrease in mean frequency was smaller after sham tDCS than after active tDCS (P = 0.073). Anodal tDCS of the left DLPFC using a high current density bi-frontal electrode montage resulted in general slowing of resting-state EEG. The similar findings observed following sham stimulation question whether the standard sham protocol is an appropriate control condition for tDCS. PMID:27375462

Normalization of sensorimotor integration by repetitive transcranial magnetic stimulation in cervical dystonia.

PubMed

Zittel, S; Helmich, R C; Demiralay, C; Münchau, A; Bäumer, T

2015-08-01

Previous studies indicated that sensorimotor integration and plasticity of the sensorimotor system are impaired in dystonia patients. We investigated motor evoked potential amplitudes and short latency afferent inhibition to examine corticospinal excitability and cortical sensorimotor integration, before and after inhibitory 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex in patients with cervical dystonia (n = 12). Motor evoked potentials were recorded from the right first dorsal interosseous muscle after application of unconditioned transcranial magnetic test stimuli and after previous conditioning electrical stimulation of the right index finger at short interstimulus intervals of 25, 30 and 40 ms. Results were compared to a group of healthy age-matched controls. At baseline, motor evoked potential amplitudes did not differ between groups. Short latency afferent inhibition was reduced in cervical dystonia patients compared to healthy controls. Inhibitory 1 Hz sensory cortex repetitive transcranial magnetic stimulation but not motor cortex repetitive transcranial magnetic stimulation increased motor evoked potential amplitudes in cervical dystonia patients. Additionally, both 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex normalized short latency afferent inhibition in these patients. In healthy subjects, sensory repetitive transcranial magnetic stimulation had no influence on motor evoked potential amplitudes and short latency afferent inhibition. Plasticity of sensorimotor circuits is altered in cervical dystonia patients.

Benefits of using transcranial magnetic stimulation as a tool to facilitate the chronic knee injury rehabilitation.

PubMed

Lee, Jae-Moo; Lee, Ji-Hang

2017-04-01

[Purpose] While primary motor cortex activation has been implicated as a key factor in the arthrogenic muscle inhibition after knee joint injury, no viable rehabilitation protocol has been developed to accommodate this factor. In this study, transcranial magnetic stimulation was applied as a means of dissipating arthrogenic muscle inhibition by introducing temporary motor cortex excitation prior to the rehabilitation. [Subjects and Methods] Twenty-four subjects who have underwent the surgery due to knee injury were recruited, and randomly assigned to the control or the simulation groups. The levels of electromyography signals during the maximum voluntary contraction of the quadriceps muscle before, during, and after training designed for the quadriceps strength rehabilitation were measured. [Results] When compared to controls, subjects who received the transcranial magnetic stimulations showed significantly increased levels of voluntary muscle contraction after the training. Moreover, the beneficial effect of the stimulation increased as the rehabilitation progressed. [Conclusion] Transcranial magnetic stimulation itself does not directly improve the symptoms related to knee injuries. However, the use of this technique can provide a time window for effective intervention by dissipating the unwanted effect of the arthrogenic muscle inhibition during rehabilitation.

Transcranial direct current stimulation improves seizure control in patients with Rasmussen encephalitis.

PubMed

Tekturk, Pinar; Erdogan, Ezgi Tuna; Kurt, Adnan; Kocagoncu, Ece; Kucuk, Zeynep; Kinay, Demet; Yapici, Zuhal; Aksu, Serkan; Baykan, Betul; Karamursel, Sacit

2016-03-01

Rasmussen encephalitis is associated with severe seizures that are unresponsive to antiepileptic drugs, as well as immunosuppressants. Transcranial direct current stimulation (t-DCS) is a non-invasive and safe method tried mostly for focal epilepsies with different aetiologies. To date, there is only one published study with two case reports describing the effect of t-DCS in Rasmussen encephalitis. Our aim was to investigate the effect of t-DCS on seizures in Rasmussen encephalitis and to clarify its safety. Five patients (mean age: 19; three females), diagnosed with Rasmussen encephalitis were included in this study. Patients received first cathodal, then anodal (2 mA for 30 minutes on three consecutive days for non-sham stimulations), and finally sham stimulation with two-month intervals, respectively. Three patients received classic (DC) cathodal t-DCS whereas two patients received cathodal stimulation with amplitude modulation at 12 Hz. Afterwards, all patients received anodal stimulation with amplitude modulation at 12 Hz. In the last part of the trial, sham stimulation (a 60-second stimulation with gradually decreasing amplitude to zero in the last 15 seconds) was applied to three patients. Maximum current density was 571 mA/m2 using 70 mm x 50 mm wet sponge electrodes with 2-mA maximum, current controlled stimulator, and maximum charge density was 1028 C/m2 for a 30-minute stimulation period. After cathodal stimulation, all but one patient had a greater than 50% decrease in seizure frequency. Two patients who received modulated cathodal t-DCS had better results. The longest positive effect lasted for one month. A second trial with modulated anodal stimulation and a third with sham stimulation were not effective. No adverse effect was reported with all types of stimulations. Both classic and modulated cathodal t-DCS may be suitable alternative methods for improving seizure outcome in Rasmussen encephalitis patients.

Assessing cortical synchronization during transcranial direct current stimulation: A graph-theoretical analysis.

PubMed

Mancini, Matteo; Brignani, Debora; Conforto, Silvia; Mauri, Piercarlo; Miniussi, Carlo; Pellicciari, Maria Concetta

2016-10-15

Transcranial direct current stimulation (tDCS) is a neuromodulation technique that can alter cortical excitability and modulate behaviour in a polarity-dependent way. Despite the widespread use of this method in the neuroscience field, its effects on ongoing local or global (network level) neuronal activity are still not foreseeable. A way to shed light on the neuronal mechanisms underlying the cortical connectivity changes induced by tDCS is provided by the combination of tDCS with electroencephalography (EEG). In this study, twelve healthy subjects underwent online tDCS-EEG recording (i.e., simultaneous), during resting-state, using 19 EEG channels. The protocol involved anodal, cathodal and sham stimulation conditions, with the active and the reference electrodes in the left frontocentral area (FC3) and on the forehead over the right eyebrow, respectively. The data were processed using a network model, based on graph theory and the synchronization likelihood. The resulting graphs were analysed for four frequency bands (theta, alpha, beta and gamma) to evaluate the presence of tDCS-induced differences in synchronization patterns and graph theory measures. The resting state network connectivity resulted altered during tDCS, in a polarity-specific manner for theta and alpha bands. Anodal tDCS weakened synchronization with respect to the baseline over the fronto-central areas in the left hemisphere, for theta band (p<0.05). In contrast, during cathodal tDCS a significant increase in inter-hemispheric synchronization connectivity was observed over the centro-parietal, centro-occipital and parieto-occipital areas for the alpha band (p<0.05). Local graph measures showed a tDCS-induced polarity-specific differences that regarded modifications of network activities rather than specific region properties. Our results show that applying tDCS during the resting state modulates local synchronization as well as network properties in slow frequency bands, in a polarity

Repeated transcranial direct current stimulation in prolonged disorders of consciousness: A double-blind cross-over study.

PubMed

Estraneo, Anna; Pascarella, Angelo; Moretta, Pasquale; Masotta, Orsola; Fiorenza, Salvatore; Chirico, Grazia; Crispino, Emanuela; Loreto, Vincenzo; Trojano, Luigi

2017-04-15

To evaluate effects of 5 sessions of transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex in patients with prolonged disorders of consciousness (DOC). Seven patients in vegetative state (VS) and 6 in minimally conscious state (MCS), at ≥3months after brain injury, were randomized into two groups: group 1 received one week of active tDCS and 1week of sham stimulation, separated by 1 resting week; group 2 received active and sham stimulation in reverse order. We performed clinical and EEG evaluations before and after the first stimulation session, two hours after the last weekly stimulation, twice during the resting week, and during a 3-month follow-up. We observed small changes of patients' conditions after the first tDCS session and immediately after the 5 active stimulations. Substantial clinical and EEG changes were observed in 5/13 patients (3 in MCS and 2 in VS) starting after entire (active and sham) stimulation protocol and further progressing during the next months. No baseline features distinguished patients who improved from patients who did not improve. Repeated tDCS did not exert remarkable short-term clinical and EEG effects in patients with prolonged DOC. Further studies should ascertain whether tDCS might promote clinical recovery in the long-term period. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of transcranial direct current stimulation (tDCS) on MMN-indexed auditory discrimination: a pilot study.

PubMed

Impey, Danielle; Knott, Verner

2015-08-01

Membrane potentials and brain plasticity are basic modes of cerebral information processing. Both can be externally (non-invasively) modulated by weak transcranial direct current stimulation (tDCS). Polarity-dependent tDCS-induced reversible circumscribed increases and decreases in cortical excitability and functional changes have been observed following stimulation of motor and visual cortices but relatively little research has been conducted with respect to the auditory cortex. The aim of this pilot study was to examine the effects of tDCS on auditory sensory discrimination in healthy participants (N = 12) assessed with the mismatch negativity (MMN) brain event-related potential (ERP). In a randomized, double-blind, sham-controlled design, participants received anodal tDCS over the primary auditory cortex (2 mA for 20 min) in one session and 'sham' stimulation (i.e., no stimulation except initial ramp-up for 30 s) in the other session. MMN elicited by changes in auditory pitch was found to be enhanced after receiving anodal tDCS compared to 'sham' stimulation, with the effects being evidenced in individuals with relatively reduced (vs. increased) baseline amplitudes and with relatively small (vs. large) pitch deviants. Additional studies are needed to further explore relationships between tDCS-related parameters, auditory stimulus features and individual differences prior to assessing the utility of this tool for treating auditory processing deficits in psychiatric and/or neurological disorders.

Using Transcranial Direct Current Stimulation to Enhance Creative Cognition: Interactions between Task, Polarity, and Stimulation Site

PubMed Central

Weinberger, Adam B.; Green, Adam E.; Chrysikou, Evangelia G.

2017-01-01

Creative cognition is frequently described as involving two primary processes, idea generation and idea selection. A growing body of research has used transcranial direct current stimulation (tDCS) to examine the neural mechanisms implicated in each of these processes. This literature has yielded a diverse set of findings that vary depending on the location and type (anodal, cathodal, or both) of electrical stimulation employed, as well as the task’s reliance on idea generation or idea selection. As a result, understanding the interactions between stimulation site, polarity and task demands is required to evaluate the potential of tDCS to enhance creative performance. Here, we review tDCS designs that have elicited reliable and dissociable enhancements for creative cognition. Cathodal stimulation over the left inferior frontotemporal cortex has been associated with improvements on tasks that rely primarily on idea generation, whereas anodal tDCS over left dorsolateral prefrontal cortex (DLPFC) and frontopolar cortex has been shown to augment performance on tasks that impose high demands on creative idea selection. These results highlight the functional selectivity of tDCS for different components of creative thinking and confirm the dissociable contributions of left dorsal and inferior lateral frontotemporal cortex for different creativity tasks. We discuss promising avenues for future research that can advance our understanding of the effectiveness of tDCS as a method to enhance creative cognition. PMID:28559804

Transcranial direct current stimulation improves naming reaction time in fluent aphasia: a double-blind, sham-controlled study.

PubMed

Fridriksson, Julius; Richardson, Jessica D; Baker, Julie M; Rorden, Chris

2011-03-01

Previous evidence suggests that anodal transcranial direct current stimulation (A-tDCS) applied to the left hemisphere can improve aphasic participants' ability to name common objects. The current study further examined this issue in a more tightly controlled experiment in participants with fluent aphasia. We examined the effect of A-tDCS on reaction time during overt picture naming in 8 chronic stroke participants. Anode electrode placement targeted perilesional brain regions that showed the greatest activation on a pretreatment functional MRI scan administered during overt picture naming with the reference cathode electrode placed on the contralateral forehead. A-tDCS (1 mA; 20-minute) was compared with sham tDCS (S-tDCS) in a crossover design. Participants received 10 sessions of computerized anomia treatment; 5 sessions included A-tDCS and 5 included S-tDCS. Coupling A-tDCS with behavioral language treatment reduced reaction time during naming of trained items immediately posttreatment (Z=1.96, P=0.025) and at subsequent testing 3 weeks later (Z=2.52, P=0.006). A-tDCS administered during language treatment decreased processing time during picture naming by fluent aphasic participants. Additional studies combining A-tDCS, an inexpensive method with no reported serious side effects, with behavioral language therapy are recommended.

What is the optimal anodal electrode position for inducing corticomotor excitability changes in transcranial direct current stimulation?

PubMed

Lee, Minji; Kim, Yun-Hee; Im, Chang-Hwan; Kim, Jung-Hoon; Park, Chang-hyun; Chang, Won Hyuk; Lee, Ahee

2015-01-01

Transcranial direct current stimulation (tDCS) non-invasively modulates brain function by inducing neuronal excitability. The conventional hot spot for inducing the highest current density in the hand motor area may not be the optimal site for effective stimulation. In this study, we investigated the influence of the center position of the anodal electrode on changes in motor cortical excitability. We considered three tDCS conditions in 16 healthy subjects: (i) real stimulation with the anodal electrode located at the conventional hand motor hot spot determined by motor evoked potentials (MEPs); (ii) real stimulation with the anodal electrode located at the point with the highest current density in the hand motor area as determined by electric current simulation; and (iii) sham stimulation. Motor cortical excitability as measured by MEP amplitude increased after both real stimulation conditions, but not after sham stimulation. Stimulation using the simulation-derived anodal electrode position, which was found to be posterior to the MEP hot spot for all subjects, induced higher motor cortical excitability. Individual positioning of the anodal electrode, based on the consideration of anatomical differences between subjects, appears to be important for maximizing the effects of tDCS. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Assessment of abdominal muscle function in individuals with motor-complete spinal cord injury above T6 in response to transcranial magnetic stimulation.

PubMed

Bjerkefors, Anna; Squair, Jordan W; Chua, Romeo; Lam, Tania; Chen, Zhen; Carpenter, Mark G

2015-02-01

To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.

Effect of transcranial direct-current stimulation combined with treadmill training on balance and functional performance in children with cerebral palsy: a double-blind randomized controlled trial.

PubMed

Duarte, Natália de Almeida Carvalho; Grecco, Luanda André Collange; Galli, Manuela; Fregni, Felipe; Oliveira, Cláudia Santos

2014-01-01

Cerebral palsy refers to permanent, mutable motor development disorders stemming from a primary brain lesion, causing secondary musculoskeletal problems and limitations in activities of daily living. The aim of the present study was to determine the effects of gait training combined with transcranial direct-current stimulation over the primary motor cortex on balance and functional performance in children with cerebral palsy. A double-blind randomized controlled study was carried out with 24 children aged five to 12 years with cerebral palsy randomly allocated to two intervention groups (blocks of six and stratified based on GMFCS level (levels I-II or level III).The experimental group (12 children) was submitted to treadmill training and anodal stimulation of the primary motor cortex. The control group (12 children) was submitted to treadmill training and placebo transcranial direct-current stimulation. Training was performed in five weekly sessions for 2 weeks. Evaluations consisted of stabilometric analysis as well as the administration of the Pediatric Balance Scale and Pediatric Evaluation of Disability Inventory one week before the intervention, one week after the completion of the intervention and one month after the completion of the intervention. All patients and two examiners were blinded to the allocation of the children to the different groups. The experimental group exhibited better results in comparison to the control group with regard to anteroposterior sway (eyes open and closed; p<0.05), mediolateral sway (eyes closed; p<0.05) and the Pediatric Balance Scale both one week and one month after the completion of the protocol. Gait training on a treadmill combined with anodal stimulation of the primary motor cortex led to improvements in static balance and functional performance in children with cerebral palsy. Ensaiosclinicos.gov.br/RBR-9B5DH7.

Combination of Transcranial Direct Current Stimulation and Neuromuscular Electrical Stimulation Improves Gait Ability in a Patient in Chronic Stage of Stroke.

PubMed

Satow, Takeshi; Kawase, Tomotaka; Kitamura, Atsushi; Kajitani, Yuki; Yamaguchi, Takuya; Tanabe, Nobuhiko; Otoi, Reiko; Komuro, Taro; Kobayashi, Akira; Nagata, Hirokazu; Mima, Tatsuya

2016-01-01

Walking ability is important in stroke patients to maintain daily life. Nevertheless, its improvement is limited with conventional physical therapy in chronic stage. We report the case of a chronic stroke patient showing a remarkable improvement in gait function after a new neurorehabilitation protocol using transcranial direct current stimulation (tDCS) and neuromuscular electrical stimulation (NMES). A 62-year-old male with left putaminal hemorrhage suffered from severe right hemiparesis. He could move by himself with a wheelchair 1 year after the ictus. Anodal tDCS at the vertex (2 mA, 20 min) with NMES at the anterior tibialis muscle had been applied for 3 weeks. The Timed Up and Go test and 10-meter walk test improved after the intervention, which had been maintained for at least 1 month. This single case suggests the possibility that tDCS with NMES could be a new rehabilitation approach to improve the gait ability in chronic stroke patients.

Testing assumptions on prefrontal transcranial direct current stimulation: Comparison of electrode montages using multimodal fMRI.

PubMed

Wörsching, Jana; Padberg, Frank; Goerigk, Stephan; Heinz, Irmgard; Bauer, Christine; Plewnia, Christian; Hasan, Alkomiet; Ertl-Wagner, Birgit; Keeser, Daniel

2018-05-04

Transcranial direct current stimulation (tDCS) of the prefrontal cortex (PFC) has been widely applied in cognitive neurosciences and advocated as a therapeutic intervention, e.g. in major depressive disorder. Although several targets and protocols have been suggested, comparative studies of tDCS parameters, particularly electrode montages and their cortical targets, are still lacking. This study investigated a priori hypotheses on specific effects of prefrontal-tDCS montages by using multimodal functional magnetic resonance imaging (fMRI) in healthy participants. 28 healthy male participants underwent three common active-tDCS montages and sham tDCS in a pseudo-randomized order, comprising a total of 112 tDCS-fMRI sessions. Active tDCS was applied at 2 mA for 20 min. Before and after tDCS, a resting-state fMRI (RS fMRI) was recorded, followed by a task fMRI with a delayed-response working-memory (DWM) task for assessing cognitive control over emotionally negative or neutral distractors. After tDCS with a cathode-F3/anode-F4 montage, RS-fMRI connectivity decreased in a medial part of the left PFC. Also, after the same stimulation condition, regional brain activity during DWM retrieval decreased more in this area after negative than after neutral distraction, and responses to the DWM task were faster, independent of distractor type. The current study does not confirm our a priori hypotheses on direction and localization of polarity-dependent tDCS effects using common bipolar electrode montages over PFC regions, but it provides evidence for montage-specific effects on multimodal neurophysiological and behavioral outcome measures. Systematic research on the actual targets and the respective dose-response relationships of prefrontal tDCS is warranted. Copyright © 2018 Elsevier Inc. All rights reserved.

Transcranial direct current stimulation versus user training on improving online myoelectric control for amputees

NASA Astrophysics Data System (ADS)

Pan, Lizhi; Zhang, Dingguo; Jiang, Ning; Sheng, Xinjun; Zhu, Xiangyang

2017-08-01

Objective. Transcranial direct current stimulation (tDCS) and user training (UT) are two types of methods to improve myoelectric control performance for amputees. In this study, we compared the independent effect between tDCS and UT, and investigated the combined effect of tDCS and UT. Approach. An online paradigm of simultaneous and proportional control (SPC) based on electromyography (EMG) was adopted. The proposed experiments were conducted on six naïve unilateral trans-radial amputees. The subjects each received three types of 20 min interventions: active tDCS with motor training (tDCS  +  UT), active tDCS with quiet sitting (tDCS), and sham tDCS with motor training (UT). The interventions were applied at one week intervals in a randomized order. The subjects performed online control of a feedback arrow with two degrees of freedom (DoFs) to accomplish target reaching motor tasks in pre-sessions and post-sessions. We compared the performance, measured by completion rate, completion time, and efficiency coefficient, between pre-sessions and post-sessions. Main results. The results showed that the intervention tDCS  +  UT and tDCS significantly improved the online SPC performance (i.e. improved the completion rate; reduced the completion time; and improved the efficiency coefficient), while intervention UT did not significantly change the performance. The results also showed that the online SPC performance after intervention tDCS  +  UT and tDCS was not significantly different, but both were significantly better than that after intervention UT. Significance. tDCS could be an effective intervention to improve the online SPC performance in a short time.

Transcranial Direct Current Stimulation (tDCS) Enhances the Excitability of Trigemino-Facial Reflex Circuits.

PubMed

Cabib, Christopher; Cipullo, Federica; Morales, Merche; Valls-Solé, Josep

2016-01-01

Transcranial direct current stimulation (tDCS) causes a tiny burning sensation through activation of local cutaneous trigeminal afferents. Trigeminal sensory inputs from tDCS may generate excitability changes in the trigemino-facial reflex circuits. Sixteen healthy volunteers were submitted to 20 minutes tDCS sessions with two types of electrode-montage conditions: 1. Real vs Sham 'bi-hemispheric' tDCS (cathode/anode: C4/C3), for blinded assessment of effects, and 2. 'uni-hemispheric' tDCS (cathode/anode: Fp3/C3), for assessment of laterality of the effects. Supraorbital nerve stimuli were used to obtain blink reflexes before, during (10 minutes from onset) and after (30 minutes from onset) the tDCS session. Outcome measures were R2 habituation (R2H) to repeated stimuli, the blink reflex excitability recovery (BRER) to paired stimuli and the blink reflex inhibition by a prepulse (BRIP). Real but not sham bi-hemispheric tDCS caused a significant decrease of R2H and leftward shift of BRER curve (p < 0.05 for all measures). The effects of uni-hemispheric tDCS on BRER and BRIP were larger on ipsilateral than on contralateral blink reflexes (p < 0.05). Excitability changes were still present 10 minutes after the end of stimulation in a lesser extent. This study shows that 20 minute tDCS enhances the excitability of trigemino-facial reflex circuits. The finding of larger ipsilateral than contralateral effects suggests that sensitization through cutaneous trigeminal afferents adds on other possible mechanisms such as activation of cortico-nuclear or cortico-reticular connections. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of Transcranial Direct-Current Stimulation on Neurosurgical Skill Acquisition: A Randomized Controlled Trial.

PubMed

Ciechanski, Patrick; Cheng, Adam; Lopushinsky, Steven; Hecker, Kent; Gan, Liu Shi; Lang, Stefan; Zareinia, Kourosh; Kirton, Adam

2017-12-01

Recent changes in surgical training environments may have limited opportunities for trainees to gain proficiency in skill. Complex skills such as neurosurgery require extended periods of training. Methods to enhance surgical training are required to overcome duty-hour restrictions, to ensure the acquisition of skill proficiency. Transcranial direct-current stimulation (tDCS) can enhance motor skill learning, but is untested in surgical procedural training. We aimed to determine the effects of tDCS on simulation-based neurosurgical skill acquisition. Medical students were trained to acquire tumor resection skills using a virtual reality neurosurgical simulator. The primary outcome of change in tumor resection was scored at baseline, over 8 repetitions, post-training, and again at 6 weeks. Participants received anodal tDCS or sham over the primary motor cortex. Secondary outcomes included changes in brain resected, resection effectiveness, duration of excessive forces (EF) applied, and resection efficiency. Additional outcomes included tDCS tolerability. Twenty-two students consented to participate, with no dropouts over the course of the trial. Participants receiving tDCS intervention increased the amount of tumor resected, increased the effectiveness of resection, reduced the duration of EF applied, and improved resection efficiency. Little or no decay was observed at 6 weeks in both groups. No adverse events were documented, and sensation severity did not differ between stimulation groups. The addition of tDCS to neurosurgical training may enhance skill acquisition in a simulation-based environment. Trials of additional skills in high-skill residents, and translation to nonsimulated performance are needed to determine the potential utility of tDCS in surgical training. Copyright © 2017 Elsevier Inc. All rights reserved.

Transcranial direct current stimulation for obsessive-compulsive disorder: A randomized, controlled, partial crossover trial.

PubMed

D'Urso, Giordano; Brunoni, Andre R; Mazzaferro, Maria Pia; Anastasia, Annalisa; de Bartolomeis, Andrea; Mantovani, Antonio

2016-12-01

Presupplementary motor area (pre-SMA) hyperactivity has been detected in obsessive-compulsive disorder (OCD) patients. However, it is not understood whether this is a putative primary cause or a compensatory mechanism in OCD pathophysiology. Considering the polarity-dependent effects on cortical excitability of transcranial direct current stimulation (tDCS), we applied cathodal and/or anodal tDCS to the pre-SMA of OCD patients to test which current polarity might better improve symptoms. Twelve OCD patients received initially 10 anodal (n = 6) or cathodal (n = 6) daily consecutive 2 mA/20 min tDCS sessions with the active electrode placed bilaterally on the pre-SMA. In case of improvement or no change in symptoms severity, the subjects were maintained on the same current polarity for 10 more sessions. In case of symptoms worsening after the first 10 sessions they were switched to the other polarity for 10 more sessions to test the hypothesis of a polarity-dependent effect. Therefore, each subject received 20 tDCS sessions. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Sheehan Disability Scale (SDS) were administered biweekly to assess changes in symptoms severity. After 10 sessions, 50% of patients who initially received anodal stimulation were switched to cathodal, while 100% of patients initially assigned to cathodal stimulation continued on the same polarity. At the end of the study, a statistically significant decrease was observed in the mean Y-BOCS scores of those patients who underwent cathodal tDCS. No pre-post difference was found in the scores of patients following anodal tDCS. Cathodal but not anodal tDCS over the pre-SMA significantly improved OCD symptoms. © 2016 Wiley Periodicals, Inc.

Reduced Current Spread by Concentric Electrodes in Transcranial Electrical Stimulation (tES).

PubMed

Bortoletto, M; Rodella, C; Salvador, R; Miranda, P C; Miniussi, C

2016-01-01

We propose the use of a new montage for transcranial direct current stimulation (tDCS), called concentric electrodes tDCS (CE-tDCS), involving two concentric round electrodes that may improve stimulation focality. To test efficacy and focality of CE-tDCS, we modelled the current distribution and tested physiological effects on cortical excitability. Motor evoked potentials (MEPs) from first dorsal interosseous (FDI) and abductor digiti minimi (ADM) were recorded before and after the delivery of anodal, cathodal and sham stimulation on the FDI hotspot for 10 minutes. MEP amplitude of FDI increased after anodal-tDCS and decreased after cathodal-tDCS, supporting the efficacy of CE-tDCS in modulating cortical excitability. Moreover, modelled current distribution and no significant effects of stimulation on MEP amplitude of ADM suggest high focality of CE-tDCS. CE-tDCS may allow a better control of current distribution and may represent a novel tool for applying tDCS and other transcranial current stimulation approaches. Copyright © 2016 Elsevier Inc. All rights reserved.

Lasting EEG/MEG Aftereffects of Rhythmic Transcranial Brain Stimulation: Level of Control Over Oscillatory Network Activity

PubMed Central

Veniero, Domenica; Vossen, Alexandra; Gross, Joachim; Thut, Gregor

2015-01-01

A number of rhythmic protocols have emerged for non-invasive brain stimulation (NIBS) in humans, including transcranial alternating current stimulation (tACS), oscillatory transcranial direct current stimulation (otDCS), and repetitive (also called rhythmic) transcranial magnetic stimulation (rTMS). With these techniques, it is possible to match the frequency of the externally applied electromagnetic fields to the intrinsic frequency of oscillatory neural population activity (“frequency-tuning”). Mounting evidence suggests that by this means tACS, otDCS, and rTMS can entrain brain oscillations and promote associated functions in a frequency-specific manner, in particular during (i.e., online to) stimulation. Here, we focus instead on the changes in oscillatory brain activity that persist after the end of stimulation. Understanding such aftereffects in healthy participants is an important step for developing these techniques into potentially useful clinical tools for the treatment of specific patient groups. Reviewing the electrophysiological evidence in healthy participants, we find aftereffects on brain oscillations to be a common outcome following tACS/otDCS and rTMS. However, we did not find a consistent, predictable pattern of aftereffects across studies, which is in contrast to the relative homogeneity of reported online effects. This indicates that aftereffects are partially dissociated from online, frequency-specific (entrainment) effects during tACS/otDCS and rTMS. We outline possible accounts and future directions for a better understanding of the link between online entrainment and offline aftereffects, which will be key for developing more targeted interventions into oscillatory brain activity. PMID:26696834

Repetitive Transcranial Magnetic Stimulation of the Primary Somatosensory Cortex Modulates Perception of the Tendon Vibration Illusion.

PubMed

Huh, D C; Lee, J M; Oh, S M; Lee, J-H; Van Donkelaar, P; Lee, D H

2016-10-01

The effect of repetitive transcranial magnetic stimulation on kinesthetic perception, when applied to the somatosensory cortex, was examined. Further, the facilitatory and inhibitory effects of repetitive transcranial magnetic stimulation using different stimulation frequencies were tested. Six female (M age = 32.0 years, SD = 6.7) and nine male (M age = 32.9 years, SD = 6.6) participants were asked to perceive the tendon vibration illusion of the left wrist joint and to replicate the illusion with their right hand. When comparing changes in the corresponding movement amplitude and velocity after three different repetitive transcranial magnetic stimulation protocols (sham, 1 Hz inhibitory, and 5 Hz facilitatory repetitive transcranial magnetic stimulation), the movement amplitude was found to decrease with the inhibitory repetitive transcranial magnetic stimulation, while the movement velocity respectively increased and decreased with the facilitatory and inhibitory repetitive transcranial magnetic stimulation. These results confirmed the modulating effects of repetitive transcranial magnetic stimulation on kinesthetic perception in a single experimental paradigm. © The Author(s) 2016.

Transcranial magnetic stimulation: language function.

PubMed

Epstein, C M

1998-07-01

Studies of language using transcranial magnetic stimulation (TMS) have focused both on identification of language areas and on elucidation of function. TMS may result in either inhibition or facilitation of language processes and may operate directly at a presumptive site of language cortex or indirectly through intracortical networks. TMS has been used to create reversible "temporary lesions," similar to those produced by Wada tests and direct cortical electrical stimulation, in cerebral cortical areas subserving language function. Rapid-rate TMS over the left inferior frontal region blocks speech output in most subjects. However, the results are not those predicted from classic models of language organization. Speech arrest is obtained most easily over facial motor cortex, and true aphasia is rare, whereas right hemisphere or bilateral lateralization is unexpectedly prominent. A clinical role for these techniques is not yet fully established. Interfering with language comprehension and verbal memory is currently more difficult than blocking speech output, but numerous TMS studies have demonstrated facilitation of language-related tasks, including oral word association, story recall, digit span, and picture naming. Conversely, speech output also facilitates motor responses to TMS in the dominant hemisphere. Such new and often-unexpected findings may provide important insights into the organization of language.

Transcranial Direct Current Stimulation Improves Executive Dysfunctions in ADHD: Implications for Inhibitory Control, Interference Control, Working Memory, and Cognitive Flexibility.

PubMed

Nejati, Vahid; Salehinejad, Mohammad Ali; Nitsche, Michael A; Najian, Asal; Javadi, Amir-Homayoun

2017-09-01

This study examined effects of transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC) on major executive functions (EFs), including response inhibition, executive control, working memory (WM), and cognitive flexibility/task switching in ADHD. ADHD children received (a) left anodal/right cathodal DLPFC tDCS and (b) sham stimulation in Experiment 1 and (a) left anodal DLPFC/right cathodal OFC tDCS, (b) left cathodal DLPFC/right anodal OFC tDCS, and (c) sham stimulation in Experiment 2. The current intensity was 1 mA for 15 min with a 72-hr interval between sessions. Participants underwent Go/No-Go task, N-back test, Wisconsin Card Sorting Test (WCST), and Stroop task after each tDCS condition. Anodal left DLPFC tDCS most clearly affected executive control functions (e.g., WM, interference inhibition), while cathodal left DLPFC tDCS improved inhibitory control. Cognitive flexibility/task switching benefited from combined DLPFC-OFC, but not DLPFC stimulation alone. Task-specific stimulation protocols can improve EFs in ADHD.

Transcranial magnetic stimulation potentiates glutamatergic neurotransmission in depressed adolescents.

PubMed

Croarkin, Paul E; Nakonezny, Paul A; Wall, Christopher A; Murphy, Lauren L; Sampson, Shirlene M; Frye, Mark A; Port, John D

2016-01-30

Abnormalities in glutamate neurotransmission may have a role in the pathophysiology of adolescent depression. The present pilot study examined changes in cortical glutamine/glutamate ratios in depressed adolescents receiving high-frequency repetitive transcranial magnetic stimulation. Ten adolescents with treatment-refractory major depressive disorder received up to 30 sessions of 10-Hz repetitive transcranial magnetic stimulation at 120% motor threshold with 3000 pulses per session applied to the left dorsolateral prefrontal cortex. Baseline, posttreatment, and 6-month follow-up proton magnetic resonance spectroscopy scans of the anterior cingulate cortex and left dorsolateral prefrontal cortex were collected at 3T with 8-cm(3) voxels. Glutamate metabolites were quantified with 2 distinct proton magnetic resonance spectroscopy sequences in each brain region. After repetitive transcranial magnetic stimulation and at 6 months of follow-up, glutamine/glutamate ratios increased in the anterior cingulate cortex and left dorsolateral prefrontal cortex with both measurements. The increase in the glutamine/glutamate ratio reached statistical significance with the TE-optimized PRESS sequence in the anterior cingulate cortex. Glutamine/glutamate ratios increased in conjunction with depressive symptom improvement. This reached statistical significance with the TE-optimized PRESS sequence in the left dorsolateral prefrontal cortex. High-frequency repetitive transcranial magnetic stimulation applied to the left dorsolateral prefrontal cortex may modulate glutamate neurochemistry in depressed adolescents. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Bihemispheric Transcranial Direct Current Stimulation Enhances Effector-Independent Representations of Motor Synergy and Sequence Learning

PubMed Central

Husain, Masud; Wiestler, Tobias; Diedrichsen, Jörn

2014-01-01

Complex manual tasks—everything from buttoning up a shirt to playing the piano—fundamentally involve two components: (1) generating specific patterns of muscle activity (here, termed “synergies”); and (2) stringing these into purposeful sequences. Although transcranial direct current stimulation (tDCS) of the primary motor cortex (M1) has been found to increase the learning of motor sequences, it is unknown whether it can similarly facilitate motor synergy learning. Here, we determined the effects of tDCS on the learning of motor synergies using a novel hand configuration task that required the production of difficult muscular activation patterns. Bihemispheric tDCS was applied to M1 of healthy, right-handed human participants during 4 d of repetitive left-hand configuration training in a double-blind design. tDCS augmented synergy learning, leading subsequently to faster and more synchronized execution. This effect persisted for at least 4 weeks after training. Qualitatively similar tDCS-associated improvements occurred during training of finger sequences in a separate subject cohort. We additionally determined whether tDCS only improved the acquisition of motor memories for specific synergies/sequences or whether it also facilitated more general parts of the motor representations, which could be transferred to novel movements. Critically, we observed that tDCS effects generalized to untrained hand configurations and untrained finger sequences (i.e., were nonspecific), as well as to the untrained hand (i.e., were effector-independent). Hence, bihemispheric tDCS may be a promising adjunct to neurorehabilitative training regimes, in which broad transfer to everyday tasks is highly desirable. PMID:24431461

Baseline effects of transcranial direct current stimulation on glutamatergic neurotransmission and large-scale network connectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunter, Michael A.; Coffman, Brian A.; Gasparovic, Charles

Transcranial direct current stimulation (tDCS) modulates glutamatergic neurotransmission and can be utilized as a novel treatment intervention for a multitude of populations. However, the exact mechanism by which tDCS modulates the brain's neural architecture, from the micro to macro scales, have yet to be investigated. In this paper, using a within-subjects design, resting-state functional magnetic resonance imaging (rs-fMRI) and proton magnetic resonance spectroscopy ( 1H MRS) were performed immediately before and after the administration of anodal tDCS over right parietal cortex. Group independent component analysis (ICA) was used to decompose fMRI scans into 75 brain networks, from which 12 resting-statemore » networks were identified that had significant voxel-wise functional connectivity to anatomical regions of interest. 1H MRS was used to obtain estimates of combined glutamate and glutamine (Glx) concentrations from bilateral intraparietal sulcus. Paired sample t-tests showed significantly increased Glx under the anodal electrode, but not in homologous regions of the contralateral hemisphere. Increases of within-network connectivity were observed within the superior parietal, inferior parietal, left frontal–parietal, salience and cerebellar intrinsic networks, and decreases in connectivity were observed in the anterior cingulate and the basal ganglia ( p<0.05, FDR-corrected). Individual differences in Glx concentrations predicted network connectivity in most of these networks. Finally, the observed relationships between glutamatergic neurotransmission and network connectivity may be used to guide future tDCS protocols that aim to target and alter neuroplastic mechanisms in healthy individuals as well as those with psychiatric and neurologic disorders.« less

Baseline effects of transcranial direct current stimulation on glutamatergic neurotransmission and large-scale network connectivity

DOE PAGES

Hunter, Michael A.; Coffman, Brian A.; Gasparovic, Charles; ...

2014-10-12

Transcranial direct current stimulation (tDCS) modulates glutamatergic neurotransmission and can be utilized as a novel treatment intervention for a multitude of populations. However, the exact mechanism by which tDCS modulates the brain's neural architecture, from the micro to macro scales, have yet to be investigated. In this paper, using a within-subjects design, resting-state functional magnetic resonance imaging (rs-fMRI) and proton magnetic resonance spectroscopy ( 1H MRS) were performed immediately before and after the administration of anodal tDCS over right parietal cortex. Group independent component analysis (ICA) was used to decompose fMRI scans into 75 brain networks, from which 12 resting-statemore » networks were identified that had significant voxel-wise functional connectivity to anatomical regions of interest. 1H MRS was used to obtain estimates of combined glutamate and glutamine (Glx) concentrations from bilateral intraparietal sulcus. Paired sample t-tests showed significantly increased Glx under the anodal electrode, but not in homologous regions of the contralateral hemisphere. Increases of within-network connectivity were observed within the superior parietal, inferior parietal, left frontal–parietal, salience and cerebellar intrinsic networks, and decreases in connectivity were observed in the anterior cingulate and the basal ganglia ( p<0.05, FDR-corrected). Individual differences in Glx concentrations predicted network connectivity in most of these networks. Finally, the observed relationships between glutamatergic neurotransmission and network connectivity may be used to guide future tDCS protocols that aim to target and alter neuroplastic mechanisms in healthy individuals as well as those with psychiatric and neurologic disorders.« less

Temporal Profile of Functional Visual Rehabilitative Outcomes Modulated by Transcranial Direct Current Stimulation (tDCS)

PubMed Central

Plow, Ela B.; Obretenova, Souzana N.; Jackson, Mary Lou; Merabet, Lotfi B.

2012-01-01

Objectives We have previously reported that transcranial direct current stimulation (tDCS) delivered to the occipital cortex enhances visual functional recovery when combined with 3 months of computer-based rehabilitative training in patients with hemianopia. The principal objective of this study was to evaluate the temporal sequence of effects of tDCS on visual recovery as they appear over the course of training and across different indicators of visual function. Methods Primary objective outcome measures were i) shifts in visual field border and ii) stimulus detection accuracy within the affected hemifield. These were compared between patients randomized to either vision restoration therapy (VRT) combined with active tDCS or VRT paired with sham tDCS. Training comprised of 2 half hour sessions, 3 times a week for 3 months. Primary outcome measures were collected at baseline (pretest), monthly interim intervals, and at posttest (3 months). As secondary outcome measures, contrast sensitivity and reading performance were collected at pretest and posttest time-points only. Results Active tDCS combined with VRT accelerated the recovery of stimulus detection as between-group differences appeared within the first month of training. In contrast, a shift in the visual field border was only evident at posttest (after 3 months of training). TDCS did not affect contrast sensitivity or reading performance. Conclusions These results suggest that tDCS may differentially affect the magnitude and sequence of visual recovery in a manner that is task- specific to the type of visual rehabilitative training strategy employed. PMID:22376226

Computational modeling of transcranial direct current stimulation (tDCS) in obesity: Impact of head fat and dose guidelines☆

PubMed Central

Truong, Dennis Q.; Magerowski, Greta; Blackburn, George L.; Bikson, Marom; Alonso-Alonso, Miguel

2013-01-01

Recent studies show that acute neuromodulation of the prefrontal cortex with transcranial direct current stimulation (tDCS) can decrease food craving, attentional bias to food, and actual food intake. These data suggest potential clinical applications for tDCS in the field of obesity. However, optimal stimulation parameters in obese individuals are uncertain. One fundamental concern is whether a thick, low-conductivity layer of subcutaneous fat around the head can affect current density distribution and require dose adjustments during tDCS administration. The aim of this study was to investigate the role of head fat on the distribution of current during tDCS and evaluate whether dosing standards for tDCS developed for adult individuals in general are adequate for the obese population. We used MRI-derived high-resolution computational models that delineated fat layers in five human heads from subjects with body mass index (BMI) ranging from “normal-lean” to “super-obese” (20.9 to 53.5 kg/m2). Data derived from these simulations suggest that head fat influences tDCS current density across the brain, but its relative contribution is small when other components of head anatomy are added. Current density variability between subjects does not appear to have a direct and/or simple link to BMI. These results indicate that guidelines for the use of tDCS can be extrapolated to obese subjects without sacrificing efficacy and/or treatment safety; the recommended standard parameters can lead to the delivery of adequate current flow to induce neuromodulation of brain activity in the obese population. PMID:24159560

Transcranial Doppler Ultrasound in Peninsular Arab Patients With Sickle Cell Disease.

PubMed

Adekile, Adekunle; Hassan, Meaad; Asbeutah, Akram; Al-Hinai, Mohamed; Trad, Omar; Farhan, Nayef

2018-05-06

Transcranial Doppler ultrasound is used to identify patients with sickle cell disease (SCD) at risk for stroke. We performed transcranial Doppler studies in patients from 4 countries in the Arabian Peninsula (Kuwait, Oman, Iraq, and United Arab Emirates) to document the prevalence of abnormal transcranial Doppler findings. The patients were recruited from outpatient clinics and studied in a steady state. Transcranial Doppler examinations were performed with standard equipment by experienced operators. The time-averaged maximum mean velocity (TAMMV) was documented in the arteries of the circle of Willis. The hemoglobin (Hb) genotype was confirmed, and the fetal Hb level and complete blood counts were determined. There were 415 patients in the study, aged 2 to 18 years (mean ± SD, 8.6 ± 3.5 years). None of the patients had an abnormal TAMMV (ie, > 200 cm/s), whereas only 13 (3.1%), all from Iraq, had conditional values (170-200 cm/s) in the right middle cerebral artery and 7 (1.7%) in the left middle cerebral artery. There were no consistent TAMMV differences among male and female patients or in patients with different Hb genotypes (sickle cell anemia, sickle cell β 0- thalassemia, and sickle D). The use of hydroxyurea was associated with a lower TAMMV, whereas a blood transfusion history had no influence. Total hemoglobin, reticulocyte count, serum bilirubin, and fetal Hb values showed varying degrees of association with the TAMMV in the different vessels. This study has demonstrated the rarity of abnormal transcranial Doppler findings among Peninsular Arab patients with SCD. The guidelines for transcranial Doppler screening in this population need further studies and recommendations. © 2018 by the American Institute of Ultrasound in Medicine.

Analysis of the effect of repeated-pulse transcranial magnetic stimulation at the Guangming point on electroencephalograms.

PubMed

Zhang, Xin; Fu, Lingdi; Geng, Yuehua; Zhai, Xiang; Liu, Yanhua

2014-03-01

Here, we administered repeated-pulse transcranial magnetic stimulation to healthy people at the left Guangming (GB37) and a mock point, and calculated the sample entropy of electroencephalo-gram signals using nonlinear dynamics. Additionally, we compared electroencephalogram sample entropy of signals in response to visual stimulation before, during, and after repeated-pulse tran-scranial magnetic stimulation at the Guangming. Results showed that electroencephalogram sample entropy at left (F3) and right (FP2) frontal electrodes were significantly different depending on where the magnetic stimulation was administered. Additionally, compared with the mock point, electroencephalogram sample entropy was higher after stimulating the Guangming point. When visual stimulation at Guangming was given before repeated-pulse transcranial magnetic stimula-tion, significant differences in sample entropy were found at five electrodes (C3, Cz, C4, P3, T8) in parietal cortex, the central gyrus, and the right temporal region compared with when it was given after repeated-pulse transcranial magnetic stimulation, indicating that repeated-pulse transcranial magnetic stimulation at Guangming can affect visual function. Analysis of electroencephalogram revealed that when visual stimulation preceded repeated pulse transcranial magnetic stimulation, sample entropy values were higher at the C3, C4, and P3 electrodes and lower at the Cz and T8 electrodes than visual stimulation followed preceded repeated pulse transcranial magnetic stimula-tion. The findings indicate that repeated-pulse transcranial magnetic stimulation at the Guangming evokes different patterns of electroencephalogram signals than repeated-pulse transcranial mag-netic stimulation at other nearby points on the body surface, and that repeated-pulse transcranial magnetic stimulation at the Guangming is associated with changes in the complexity of visually evoked electroencephalogram signals in parietal regions, central gyrus

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines

PubMed Central

Antal, A.; Alekseichuk, I.; Bikson, M.; Brockmöller, J.; Brunoni, A.R.; Chen, R.; Cohen, L.G.; Dowthwaite, G.; Ellrich, J.; Flöel, A.; Fregni, F.; George, M.S.; Hamilton, R.; Haueisen, J.; Herrmann, C.S.; Hummel, F.C.; Lefaucheur, J.P.; Liebetanz, D.; Loo, C.K.; McCaig, C.D.; Miniussi, C.; Miranda, P.C.; Moliadze, V.; Nitsche, M.A.; Nowak, R.; Padberg, F.; Pascual-Leone, A.; Poppendieck, W.; Priori, A.; Rossi, S.; Rossini, P.M.; Rothwell, J.; Rueger, M.A.; Ruffini, G.; Schellhorn, K.; Siebner, H.R.; Ugawa, Y.; Wexler, A.; Ziemann, U.; Hallett, M.; Paulus, W.

2018-01-01

Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1–2 mA and during tACS at higher peak-to-peak intensities above 2 mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity ‘conventional’ TES defined as <4 mA, up to 60 min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3–13 A/m2 that are over an order of magnitude above those

Low intensity transcranial electric stimulation: Safety, ethical, legal regulatory and application guidelines.

PubMed

Antal, A; Alekseichuk, I; Bikson, M; Brockmöller, J; Brunoni, A R; Chen, R; Cohen, L G; Dowthwaite, G; Ellrich, J; Flöel, A; Fregni, F; George, M S; Hamilton, R; Haueisen, J; Herrmann, C S; Hummel, F C; Lefaucheur, J P; Liebetanz, D; Loo, C K; McCaig, C D; Miniussi, C; Miranda, P C; Moliadze, V; Nitsche, M A; Nowak, R; Padberg, F; Pascual-Leone, A; Poppendieck, W; Priori, A; Rossi, S; Rossini, P M; Rothwell, J; Rueger, M A; Ruffini, G; Schellhorn, K; Siebner, H R; Ugawa, Y; Wexler, A; Ziemann, U; Hallett, M; Paulus, W

2017-09-01

Low intensity transcranial electrical stimulation (TES) in humans, encompassing transcranial direct current (tDCS), transcutaneous spinal Direct Current Stimulation (tsDCS), transcranial alternating current (tACS), and transcranial random noise (tRNS) stimulation or their combinations, appears to be safe. No serious adverse events (SAEs) have been reported so far in over 18,000 sessions administered to healthy subjects, neurological and psychiatric patients, as summarized here. Moderate adverse events (AEs), as defined by the necessity to intervene, are rare, and include skin burns with tDCS due to suboptimal electrode-skin contact. Very rarely mania or hypomania was induced in patients with depression (11 documented cases), yet a causal relationship is difficult to prove because of the low incidence rate and limited numbers of subjects in controlled trials. Mild AEs (MAEs) include headache and fatigue following stimulation as well as prickling and burning sensations occurring during tDCS at peak-to-baseline intensities of 1-2mA and during tACS at higher peak-to-peak intensities above 2mA. The prevalence of published AEs is different in studies specifically assessing AEs vs. those not assessing them, being higher in the former. AEs are frequently reported by individuals receiving placebo stimulation. The profile of AEs in terms of frequency, magnitude and type is comparable in healthy and clinical populations, and this is also the case for more vulnerable populations, such as children, elderly persons, or pregnant women. Combined interventions (e.g., co-application of drugs, electrophysiological measurements, neuroimaging) were not associated with further safety issues. Safety is established for low-intensity 'conventional' TES defined as <4mA, up to 60min duration per day. Animal studies and modeling evidence indicate that brain injury could occur at predicted current densities in the brain of 6.3-13A/m 2 that are over an order of magnitude above those produced by

Transcranial Magnetic Stimulation: Basic Principles and Clinical Applications in Migraine.

PubMed

Barker, Anthony T; Shields, Kevin

2017-03-01

Transcranial magnetic stimulation (TMS) is a neurophysiological technique with a long established pedigree of safety, tolerability, and efficacy. Initially TMS was used to study the function of the cerebral cortex, but it has now become a treatment for migraine, one of the most common and debilitating neurological conditions. In this review we discuss the scientific background and development of the technique. We explore its application for the treatment of migraine and ponder the possible mechanisms of action in this most common neurological condition. The generation of brief magnetic pulses by a suitable coil can induce electrical fields in the body. When applied to the cerebral cortex, currents are painlessly induced in cortical neurons. These currents can lead to neuronal depolarization and may influence cortical excitability by means that are as yet not fully understood. This ability to modulate cortical excitability has been exploited as a treatment for migraine with aura. Aura is implicated in the pathophysiology of migraine. Experimental studies have shown that transcranial magnetic pulses can block waves of cortical spreading depression - the experimental equivalent of migrainous aura. Migraine is a debilitating condition characterized by headache, nausea, and sensory hypersensitivity. It may affect up to 15% of the population, yet current drug treatments are often poorly tolerated. Clinical studies have shown that TMS is an effective treatment for migraine. In addition, it has the added advantages of being safe and well tolerated by patients. © 2016 American Headache Society.

Effects of transcranial random noise stimulation (tRNS) on affect, pain and attention in multiple sclerosis.

PubMed

Palm, Ulrich; Chalah, Moussa A; Padberg, Frank; Al-Ani, Tarik; Abdellaoui, Mohamed; Sorel, Marc; Dimitri, Dalia; Créange, Alain; Lefaucheur, Jean-Pascal; Ayache, Samar S

2016-01-01

Pain and cognitive impairment are frequent symptoms in patients with multiple sclerosis (MS). Neglecting experimental pain and paying attention to demanding tasks is reported to decrease the pain intensity. Little is known about the interaction between chronic neuropathic pain and attention disorders in MS. Recently, transcranial direct current stimulation (tDCS) was used to modulate various cognitive and motor symptoms in MS. We aimed to study the effects of transcranial random noise stimulation (tRNS), a form of transcranial electric stimulation, over the left dorsolateral prefrontal cortex (DLPFC) on attention and neuropathic pain in MS patients. 16 MS patients were included in a randomized, sham-controlled, cross-over study. Each patient randomly received two tRNS blocks, separated by three weeks of washout interval. Each block consisted of three consecutive daily sessions of either active or sham tRNS. The patients were evaluated for pain, attention and mood and further underwent an electrophysiological evaluation. Compared to sham, tRNS showed a trend to decrease the N2-P2 amplitudes of pain related evoked potentials and improve pain ratings. Attention performance and mood scales did not change after stimulations. This study suggests the role of tRNS in pain modulation, which could have been more evident with longer stimulation protocols.

Transesophageal versus transcranial motor evoked potentials to monitor spinal cord ischemia.

PubMed

Tsuda, Kazumasa; Shiiya, Norihiko; Takahashi, Daisuke; Ohkura, Kazuhiro; Yamashita, Katsushi; Kando, Yumi; Arai, Yoshifumi

2016-02-01

We have previously reported that transesophageal motor evoked potential is feasible and more stable than transcranial motor evoked potential. This study aimed to investigate the efficacy of transesophageal motor evoked potential to monitor spinal cord ischemia. Transesophageal and transcranial motor evoked potentials were recorded in 13 anesthetized dogs at the bilateral forelimbs, anal sphincters, and hindlimbs. Spinal cord ischemia was induced by aortic balloon occlusion at the 8th to 10th thoracic vertebra level. In the 12 animals with motor evoked potential disappearance, occlusion was maintained for 10 minutes (n = 6) or 40 minutes (n = 6) after motor evoked potential disappearance. Neurologic function was evaluated by Tarlov score at 24 and 48 hours postoperatively. Time to disappearance of bilateral motor evoked potentials was quicker in transesophageal motor evoked potentials than in transcranial motor evoked potentials at anal sphincters (6.9 ± 3.1 minutes vs 8.3 ± 3.4 minutes, P = .02) and hindlimbs (5.7 ± 1.9 minutes vs 7.1 ± 2.7 minutes, P = .008). Hindlimb function was normal in all dogs in the 10-minute occlusion group, and motor evoked potentials recovery (>75% on both sides) after reperfusion was quicker in transesophageal motor evoked potentials than transcranial motor evoked potentials at hindlimbs (14.8 ± 5.6 minutes vs 24.7 ± 8.2 minutes, P = .001). At anal sphincters, transesophageal motor evoked potentials always reappeared (>25%), but transcranial motor evoked potentials did not in 3 of 6 dogs. In the 40-minute occlusion group, hindlimb motor evoked potentials did not reappear in 4 dogs with paraplegia. Among the 2 remaining dogs, 1 with paraparesis (Tarlov 3) showed delayed recovery (>75%) of hindlimb motor evoked potentials without reappearance of anal sphincter motor evoked potentials. In another dog with spastic paraplegia, transesophageal motor evoked potentials from the hindlimbs remained less than 20%, whereas transcranial motor

Application and outcomes of therapy combining transcranial direct current stimulation and virtual reality: a systematic review.

PubMed

Massetti, Thais; Crocetta, Tânia Brusque; Silva, Talita Dias da; Trevizan, Isabela Lopes; Arab, Claudia; Caromano, Fátima Aparecida; Monteiro, Carlos Bandeira de Mello

2017-08-01

To evaluate the methods and major outcomes of transcranial direct current stimulation (tDCS) combined with virtual reality (VR) therapy in randomized controlled trials. A systematic review was performed following PRISMA guidelines using PubMed, PubMed Central, Web of Science and CAPES periodic databases, with no time restriction. The studies were screened for the following inclusion criteria: human subjects, combination of VR and tDCS methods, and randomized controlled study design. All potentially relevant articles were independently reviewed by two researchers, who reached a consensus on which articles met the inclusion criteria. The PEDro scale was used to evaluate the studies. Eleven studies were included, all of which utilized a variety of tDCS and VR application methods. The main outcomes were found to be beneficial in intervention groups of different populations, including improvements in body sway, gait, stroke recovery, pain management and vegetative reactions. The use of tDCS combined with VR showed positive results in both healthy and impaired patients. Future studies with larger sample sizes and homogeneous participants are required to confirm the benefits of tDCS and VR. Implications for Rehabilitation tDCS with VR intervention can be an alternative to traditional rehabilitation programs. tDCS with VR is a promising type of intervention with a variety of positive effects. Application of tDCS with VR is appropriated to both healthy and impaired patients. There is no consensus of tDCS with VR application.

High-Definition Transcranial Direct Current Stimulation Enhances Conditioned Pain Modulation in Healthy Volunteers: A Randomized Trial.

PubMed

Flood, Andrew; Waddington, Gordon; Cathcart, Stuart

2016-05-01

Transcranial direct current stimulation (tDCS) is a form of brain stimulation that allows for the selective increase or decrease in the cortical excitability of a targeted region. When applied over the motor cortex it has been shown to induce changes in cortical and subcortical brain regions involved in descending pain inhibition or conditioned pain modulation (CPM). The aim of the current study was to assess whether activation of pain inhibitory pathways via tDCS of the motor cortex facilitates the CPM response. Elevated CPM after active tDCS of the motor cortex was hypothesized. Thirty healthy male volunteers attended 2 experimental sessions separated by 7 days. Both sessions consisted of CPM assessment after 20 minutes of either active or sham (placebo) tDCS over the motor cortex. CPM capacity was assessed via the pain-inhibits-pain protocol; CPM responses were shown to be elevated after active compared with sham tDCS. This report concludes that tDCS of the motor cortex enhances the CPM response in healthy men. This finding supports the potential utility of tDCS interventions in clinical pain treatment. The use of noninvasive brain stimulation over the motor cortex was shown to enhance the CPM effect. This finding supports the use of tDCS in the treatment of chronic pain, particularly in sufferers exhibiting maladaptive CPM. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

The effect of the anodal transcranial direct current stimulation over the cerebellum on the motor cortex excitability.

PubMed

Ates, Mehlika Panpalli; Alaydin, Halil Can; Cengiz, Bulent

2018-04-25

This study was designed to investigate whether the cerebellum has an inhibitory effect on motor cortical excitability. Sixteen healthy adults (age range, 25-50 years, five female) participated in the study. Anodal cerebellar transcranial direct current stimulation (a-cTDCS) was used to modulate cerebellar excitability. A-cTDCS was given for 20 min at 1 mA intensity. The automatic threshold tracking method was used to investigate cortical excitability. Resting motor threshold (RMT), short interval intracortical inhibition (SICI), short interval intracortical facilitation (SICF), intracortical facilitation (ICF), and the input output curve (I-O curve) were motor cortical excitability parameters. a-cTDCS caused a reduction in overall SICI and the reduced SICF for interstimulus intervals (ISIs) to 2.4-4.4 ms. a-cTDCS has no effect on ICF, RMT, and the I-O curve. There were no significant changes in any of these cortical excitability parameters after sham cTDCS. Results of the study indicate that a-cTDCS has a dual (both inhibitory and excitatory) effect on motor cortical excitability, rather than a simple inhibitory effect. The cerebellum modulates both the inhibitory and facilitatory activities of motor cortex (M1) and suggest that cerebello-cerebral motor connectivity is more complex than solely inhibitory or facilitatory connections. Copyright © 2018 Elsevier Inc. All rights reserved.

Transcranial direct current stimulation to primary motor area improves hand dexterity and selective attention in chronic stroke.

PubMed

Au-Yeung, Stephanie S Y; Wang, Juliana; Chen, Ye; Chua, Eldrich

2014-12-01

The aim of this study was to determine whether transcranial direct current stimulation (tDCS) applied to the primary motor hand area modulates hand dexterity and selective attention after stroke. This study was a double-blind, placebo-controlled, randomized crossover trial involving subjects with chronic stroke. Ten stroke survivors with some pinch strength in the paretic hand received three different tDCS interventions assigned in random order in separate sessions-anodal tDCS targeting the primary motor area of the lesioned hemisphere (M1lesioned), cathodal tDCS applied to the contralateral hemisphere (M1nonlesioned), and sham tDCS-each for 20 mins. The primary outcome measures were Purdue pegboard test scores for hand dexterity and response time in the color-word Stroop test for selective attention. Pinch strength of the paretic hand was the secondary outcome. Cathodal tDCS to M1nonlesioned significantly improved affected hand dexterity (by 1.1 points on the Purdue pegboard unimanual test, P = 0.014) and selective attention (0.6 secs faster response time on the level 3 Stroop interference test for response inhibition, P = 0.017), but not pinch strength. The outcomes were not improved with anodal tDCS to M1lesioned or sham tDCS. Twenty minutes of cathodal tDCS to M1nonlesioned can promote both paretic hand dexterity and selective attention in people with chronic stroke.

Anodal transcranial direct current stimulation over right dorsolateral prefrontal cortex alters decision making during approach-avoidance conflict.

PubMed

Chrysikou, Evangelia G; Gorey, Claire; Aupperle, Robin L

2017-03-01

Approach-avoidance conflict (AAC) refers to situations associated with both rewarding and threatening outcomes. The AAC task was developed to measure AAC decision-making. Approach behavior during this task has been linked to self-reported anxiety sensitivity and has elicited anterior cingulate, insula, caudate and right dorsolateral prefrontal cortex (dlPFC) activity, with right lateral PFC tracking the extent of approach behavior. Guided by these results, we used excitatory transcranial direct current stimulation (tDCS) to demonstrate the causal involvement of right dlPFC in AAC decision-making. Participants received anodal tDCS at 1.5mA over either left or right dlPFC or sham stimulation, while performing the AAC task and a control short-term memory task. Analyses of variance (ANOVA) revealed that for individuals with high anxiety sensitivity excitatory right (but not left or sham) dlPFC stimulation elicited measurable decreases in approach behavior during conflict. Excitatory left (but not right or sham) dlPFC simulation improved performance on the control task. These results support a possible asymmetry between the contributions of right and left dlPFC to AAC resolution during emotional decision-making. Increased activity in right dlPFC may contribute to anxiety-related symptoms and, as such, serve as a neurobehavioral target of anxiolytic treatments aiming to decrease avoidance behavior. © The Author (2016). Published by Oxford University Press.

Value and Efficacy of Transcranial Direct Current Stimulation in the Cognitive Rehabilitation: A Critical Review Since 2000

PubMed Central

Cappon, Davide; Jahanshahi, Marjan; Bisiacchi, Patrizia

2016-01-01

Non-invasive brain stimulation techniques, including transcranial direct current stimulation (t-DCS) have been used in the rehabilitation of cognitive function in a spectrum of neurological disorders. The present review outlines methodological communalities and differences of t-DCS procedures in neurocognitive rehabilitation. We consider the efficacy of tDCS for the management of specific cognitive deficits in four main neurological disorders by providing a critical analysis of recent studies that have used t-DCS to improve cognition in patients with Parkinson's Disease, Alzheimer's Disease, Hemi-spatial Neglect, and Aphasia. The evidence from this innovative approach to cognitive rehabilitation suggests that tDCS can influence cognition. However, the results show a high variability between studies both in terms of the methodological approach adopted and the cognitive functions targeted. The review also focuses both on methodological issues such as technical aspects of the stimulation (electrode position and dimension; current intensity; duration of protocol) and on the inclusion of appropriate assessment tools for cognition. A further aspect considered is the optimal timing for administration of tDCS: before, during or after cognitive rehabilitation. We conclude that more studies using common methodology are needed to gain a better understanding of the efficacy of tDCS as a new tool for rehabilitation of cognitive disorders in a range of neurological disorders. PMID:27147949

Value and Efficacy of Transcranial Direct Current Stimulation in the Cognitive Rehabilitation: A Critical Review Since 2000.

PubMed

Cappon, Davide; Jahanshahi, Marjan; Bisiacchi, Patrizia

2016-01-01

Non-invasive brain stimulation techniques, including transcranial direct current stimulation (t-DCS) have been used in the rehabilitation of cognitive function in a spectrum of neurological disorders. The present review outlines methodological communalities and differences of t-DCS procedures in neurocognitive rehabilitation. We consider the efficacy of tDCS for the management of specific cognitive deficits in four main neurological disorders by providing a critical analysis of recent studies that have used t-DCS to improve cognition in patients with Parkinson's Disease, Alzheimer's Disease, Hemi-spatial Neglect, and Aphasia. The evidence from this innovative approach to cognitive rehabilitation suggests that tDCS can influence cognition. However, the results show a high variability between studies both in terms of the methodological approach adopted and the cognitive functions targeted. The review also focuses both on methodological issues such as technical aspects of the stimulation (electrode position and dimension; current intensity; duration of protocol) and on the inclusion of appropriate assessment tools for cognition. A further aspect considered is the optimal timing for administration of tDCS: before, during or after cognitive rehabilitation. We conclude that more studies using common methodology are needed to gain a better understanding of the efficacy of tDCS as a new tool for rehabilitation of cognitive disorders in a range of neurological disorders.

Randomized, sham-controlled trial based on transcranial direct current stimulation and wrist robot-assisted integrated treatment on subacute stroke patients: Intermediate results.

PubMed

Mazzoleni, Stefano; Tran, Vi Do; Iardella, Laura; Dario, Paolo; Posteraro, Federico

2017-07-01

The main goal of this study is to analyse the effects of combined transcranial direct current stimulation (tDCS) and wrist robot-assisted therapy in subacute stroke patients. Twenty-four patients were included in this study and randomly assigned to the experimental (EG) or control group (CG). All participants performed wrist robot-assisted training a) in conjunction with tDCS (real stimulation for patients in EG) or b) without tDCS (sham stimulation for patients in CG). Clinical scales and kinematic parameters recorded by the robot were used for the assessment. Clinical outcome measures show a significant decrease in motor impairment after the treatment in both groups. Kinematic data show several significant improvements after the integrated therapy in both groups. However, no significant differences in both clinical outcome measures and kinematic parameters was found between two groups. The potential advantages of combined tDCS and wrist robot-assisted therapy in subacute stroke patients are still unclear.

Evidence That the Directly Imaged Planet HD 131399 Ab Is a Background Star

NASA Astrophysics Data System (ADS)

Nielsen, Eric L.; De Rosa, Robert J.; Rameau, Julien; Wang, Jason J.; Esposito, Thomas M.; Millar-Blanchaer, Maxwell A.; Marois, Christian; Vigan, Arthur; Ammons, S. Mark; Artigau, Etienne; Bailey, Vanessa P.; Blunt, Sarah; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, René; Duchêne, Gaspard; Fabrycky, Daniel; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Jensen-Clem, Rebecca; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Metchev, Stanimir; Morzinski, Katie M.; Murray-Clay, Ruth A.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Pueyo, Laurent; Rafikov, Roman R.; Rajan, Abhijith; Rantakyrö, Fredrik T.; Ruffio, Jean-Baptiste; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

2017-12-01

We present evidence that the recently discovered, directly imaged planet HD 131399 Ab is a background star with nonzero proper motion. From new JHK1L‧ photometry and spectroscopy obtained with the Gemini Planet Imager, VLT/SPHERE, and Keck/NIRC2, and a reanalysis of the discovery data obtained with VLT/SPHERE, we derive colors, spectra, and astrometry for HD 131399 Ab. The broader wavelength coverage and higher data quality allow us to reinvestigate its status. Its near-infrared spectral energy distribution excludes spectral types later than L0 and is consistent with a K or M dwarf, which are the most likely candidates for a background object in this direction at the apparent magnitude observed. If it were a physically associated object, the projected velocity of HD 131399 Ab would exceed escape velocity given the mass and distance to HD 131399 A. We show that HD 131399 Ab is also not following the expected track for a stationary background star at infinite distance. Solving for the proper motion and parallax required to explain the relative motion of HD 131399 Ab, we find a proper motion of 12.3 mas yr-1. When compared to predicted background objects drawn from a galactic model, we find this proper motion to be high but consistent with the top 4% fastest-moving background stars. From our analysis, we conclude that HD 131399 Ab is a background K or M dwarf.

Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches

NASA Astrophysics Data System (ADS)

Alexandrov, A.; Asada, T.; Buonaura, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; Di Crescenzo, A.; Di Marco, N.; Di Vacri, M. L.; Furuya, S.; Galati, G.; Gentile, V.; Katsuragawa, T.; Laubenstein, M.; Lauria, A.; Loverre, P. F.; Machii, S.; Monacelli, P.; Montesi, M. C.; Naka, T.; Pupilli, F.; Rosa, G.; Sato, O.; Strolin, P.; Tioukov, V.; Umemoto, A.; Yoshimoto, M.

2016-07-01

Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the neutron-induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 per year per kilogram, fully compatible with the design of a 10 kg × year exposure.

Right-to-left shunt detection sensitivity with air-saline and air-succinil gelatin transcranial Doppler.

PubMed

Puledda, Francesca; Toscano, Massimiliano; Pieroni, Alessio; Veneroso, Gabriele; Di Piero, Vittorio; Vicenzini, Edoardo

2016-02-01

Air-saline transcranial Doppler is nowadays the first-choice examination to identify right-to-left shunt. To increase right-to-left shunt detection in echocardiography, cardiologists also use air-gelatin mixtures, which are more stable, more echogenic, and easier to be prepared. We assessed the sensitivity of air-gelatin compared with air-saline for transcranial Doppler right-to-left shunt detection. Air-saline transcranial Doppler, during unilateral middle cerebral artery monitoring at rest and after Valsalva maneuver, was performed in patients referred to our neurosonology laboratory for right-to-left shunt detection. The same transcranial Doppler protocol was repeated with air-gelatin. To consider transcranial Doppler positive for cardiac right-to-left shunt, at least one embolic signal had to be detected within 20″ from contrast injection. Later signals were interpreted of pulmonary origin. Trans-thoracic echocardiography was repeated with both air-saline and air-gelatin. A total of 97 patients were enrolled; 46 had negative transcranial Doppler for cardiac right-to-left shunt with both air-saline and air-gelatin; out of these, four patients with air-saline plus two more patients with air-gelatin presented late, isolated microemboli, slightly more numerous with air-gelatin: these were interpreted as pulmonary shunts and confirmed with trans-thoracic echocardiography. In 28 patients with already early positive air-saline transcranial Doppler at rest, air-gelatin induced a marked right-to-left shunt increase, facilitating its visualization at trans-thoracic echocardiography. In 23 patients in whom air-saline transcranial Doppler was negative at rest and positive for cardiac right-to-left shunt only after Valsalva maneuver, air-gelatin was able to reveal shunt also at rest. Air-gelatin increases right-to-left shunt detection sensitivity with transcranial Doppler in particular at rest, even in patients in whom air-saline mixture fails to identify the shunt. The

Repetitive transcranial magnetic stimulation as an alternative therapy for dysphagia after stroke: a systematic review and meta-analysis.

PubMed

Liao, Xiang; Xing, Guoqiang; Guo, Zhiwei; Jin, Yu; Tang, Qing; He, Bin; McClure, Morgan A; Liu, Hua; Chen, Huaping; Mu, Qiwen

2017-03-01

A meta-analysis and systematic review was conducted to investigate the potential effects of repetitive transcranial magnetic stimulation on dysphagia in patients with stroke, including different parameters of frequency and stimulation site. PubMed, Embase, MEDLINE databases and the Cochrane Library, were searched for randomized controlled studies of repetitive transcranial magnetic stimulation treatment of dysphagia published before March 2016. Six clinical randomized controlled studies of a total of 163 stroke patients were included in this meta-analysis. A significant effect size of 1.24 was found for dysphagic outcome (mean effect size, 1.24; 95% confidence interval (CI), 0.67-1.81). A subgroup analysis based on frequency showed that the clinical scores were significantly improved in dysphagic patients with low frequency repetitive transcranial magnetic stimulation treatment ( P < 0.05) as well as high frequency repetitive transcranial magnetic stimulation treatment ( P < 0.05). A stimulation site stratified subgroup analysis implied significant changes in stroke patients with dysphagia for the unaffected hemisphere ( P < 0.05) and the bilateral hemisphere stimulation ( P < 0.05), but not for the affected hemisphere ( P > 0.05). The analysis of the follow-up data shows that patients in the repetitive transcranial magnetic stimulation groups still maintained the therapeutic benefit of repetitive transcranial magnetic stimulation four weeks after the last session of repetitive transcranial magnetic stimulation therapy ( P < 0.05). This meta-analysis indicates that repetitive transcranial magnetic stimulation has a positive effect on dysphagia after stroke. Compared with low-frequency repetitive transcranial magnetic stimulation, high-frequency repetitive transcranial magnetic stimulation may be more beneficial to the patients. This meta-analysis also supports that repetitive transcranial magnetic stimulation on an unaffected - or bilateral

Clinical predictors of acute response to transcranial direct current stimulation (tDCS) in major depression.

PubMed

D'Urso, Giordano; Dell'Osso, Bernardo; Rossi, Rodolfo; Brunoni, Andre Russowsky; Bortolomasi, Marco; Ferrucci, Roberta; Priori, Alberto; de Bartolomeis, Andrea; Altamura, Alfredo Carlo

2017-09-01

Transcranial direct current stimulation (tDCS) is a promising neuromodulation intervention for poor-responding or refractory depressed patients. However, little is known about predictors of response to this therapy. The present study aimed to analyze clinical predictors of response to tDCS in depressed patients. Clinical data from 3 independent tDCS trials on 171 depressed patients (including unipolar and bipolar depression), were pooled and analyzed to assess predictors of response. Depression severity and the underlying clinical dimensions were measured using the Hamilton Depression Rating Scale (HDRS) at baseline and after the tDCS treatment. Age, gender and diagnosis (bipolar/unipolar depression) were also investigated as predictors of response. Linear mixed models were fitted in order to ascertain which HDRS factors were associated with response to tDCS. Age, gender and diagnosis did not show any association with response to treatment. The reduction in HDRS scores after tDCS was strongly associated with the baseline values of "Cognitive Disturbances" and "Retardation" factors, whilst the "Anxiety/Somatization" factor showed a mild association with the response. Open-label design, the lack of control group, and minor differences in stimulation protocols. No differences in response to tDCS were found between unipolar and bipolar patients, suggesting that tDCS is effective for both conditions. "Cognitive disturbance", "Retardation", and "Anxiety/Somatization", were identified as potential clinical predictors of response to tDCS. These findings point to the pre-selection of the potential responders to tDCS, therefore optimizing the clinical use of this technique and the overall cost-effectiveness of the psychiatric intervention for depressed patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Differential effects of bihemispheric and unihemispheric transcranial direct current stimulation in young and elderly adults in verbal learning.

PubMed

Fiori, Valentina; Nitsche, Michael; Iasevoli, Luigi; Cucuzza, Gabriella; Caltagirone, Carlo; Marangolo, Paola

2017-03-15

For the past few years, the potential of transcranial direct current stimulation (tDCS) for the treatment of several pathologies has been investigated. In the language domain, several studies, in healthy and brain-damaged populations, have already shown that tDCS is effective in enhancing naming, repetition and semantic word generation. In those studies, different tDCS electrode configurations have been tested, however, a direct comparison between different montages in verbal learning has never been conducted. In this study, we aimed to explore the impact of bihemispheric and unihemispheric tDCS on verbal learning task performance in two groups (young vs. elderly). Fifteen healthy volunteers participated per group. Each participant received three stimulation conditions: unihemispheric anodal tDCS over the left temporal area, bihemispheric tDCS over the left (anodal) and right (cathodal) temporal areas and a sham condition. During active stimulation, tDCS (20min, 2mA) was applied while each participant learned twenty pseudowords (arbitrarily assigned to corresponding pictures). No significant differences were found between the three conditions for the young group with regard to accuracy and vocal reaction times. In contrast, in the elderly group, real stimulation improved performance compared to sham but bihemispheric tDCS was more efficient than unilateral stimulation. These results suggest that bihemispheric stimulation is more effective in improving language learning but this effect is age-dependent. The hypothesis is advanced that cortical changes in the course of aging might differentially impact on tDCS efficacy on behavioral performance. These data may also have implications for treatment of stroke patients with language impairment. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Parkinson's Disease in Transcranial Magnetic Stimulation Treatment

NASA Astrophysics Data System (ADS)

Syeda, Farheen; Magsood, Hamzah; Lee, Erik; El-Gendy, Ahmed; Jiles, David; Hadimani, Ravi

Transcranial Magnetic Stimulation is a non-invasive clinical therapy used to treat depression and migraine, and shows further promise as treatment for Parkinson's disease, Alzheimer's disease, and other neurological disorders. However, it is yet unclear as to how anatomical differences may affect stimulation from this treatment. We use finite element analysis to model and analyze the results of Transcranial Magnetic Stimulation in various head models. A number of heterogeneous head models have been developed using MRI data of real patients, including healthy individuals as well as patients of Parkinson's disease. Simulations of Transcranial Magnetic Stimulation performed on 22 anatomically different models highlight the differences in induced stimulation. A standard Figure of 8 coil is used with frequency 2.5 kHz, placed 5 mm above the head. We compare cortical stimulation, volume of brain tissue stimulated, specificity, and maximum E-field induced in the brain for models ranging from ages 20 to 60. Results show that stimulation varies drastically between patients of the same age and health status depending upon brain-scalp distance, which is not necessarily a linear progression with age.

Outputs of paired Gabor filters summed across the background frame of reference predict the direction of movement

NASA Technical Reports Server (NTRS)

Lawton, Teri B.

1989-01-01

A cortical neural network that computes the visibility of shifts in the direction of movement is proposed. The network computes: (1) the magnitude of the position difference between the test and background patterns, (2) localized contrast differences at different spatial scales analyzed by computing temporal gradients of the difference and sum of the outputs of paired even- and odd-symmetric bandpass filters convolved with the input pattern, and (3) using global processes that pool the output from paired even- and odd-symmetric simple and complex cells across the spatial extent of the background frame of reference the direction a test pattern moved relative to a textured background. Evidence that magnocellular pathways are used to discriminate the direction of movement is presented. Since magnocellular pathways are used to discriminate the direction of movement, this task is not affected by small pattern changes such as jitter, short presentations, blurring, and different background contrasts that result when the veiling illumination in a scene changes.

The role of early stages of cortical visual processing in size and distance judgment: a transcranial direct current stimulation study.

PubMed

Costa, Thiago L; Costa, Marcelo F; Magalhães, Adsson; Rêgo, Gabriel G; Nagy, Balázs V; Boggio, Paulo S; Ventura, Dora F

2015-02-19

Recent research suggests that V1 plays an active role in the judgment of size and distance. Nevertheless, no research has been performed using direct brain stimulation to address this issue. We used transcranial direct-current stimulation (tDCS) to directly modulate the early stages of cortical visual processing while measuring size and distance perception with a psychophysical scaling method of magnitude estimation in a repeated-measures design. The subjects randomly received anodal, cathodal, and sham tDCS in separate sessions starting with size or distance judgment tasks. Power functions were fit to the size judgment data, whereas logarithmic functions were fit to distance judgment data. Slopes and R(2) were compared with separate repeated-measures analyses of variance with two factors: task (size vs. distance) and tDCS (anodal vs. cathodal vs. sham). Anodal tDCS significantly decreased slopes, apparently interfering with size perception. No effects were found for distance perception. Consistent with previous studies, the results of the size task appeared to reflect a prothetic continuum, whereas the results of the distance task seemed to reflect a metathetic continuum. The differential effects of tDCS on these tasks may support the hypothesis that different physiological mechanisms underlie judgments on these two continua. The results further suggest the complex involvement of the early visual cortex in size judgment tasks that go beyond the simple representation of low-level stimulus properties. This supports predictive coding models and experimental findings that suggest that higher-order visual areas may inhibit incoming information from the early visual cortex through feedback connections when complex tasks are performed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A pragmatic analysis of the regulation of consumer transcranial direct current stimulation (TDCS) devices in the United States

PubMed Central

2015-01-01

Several recent articles have called for the regulation of consumer transcranial direct current stimulation (tDCS) devices, which provide low levels of electrical current to the brain. However, most of the discussion to-date has focused on ethical or normative considerations; there has been a notable absence of scholarship regarding the actual legal framework in the United States. This article aims to fill that gap by providing a pragmatic analysis of the consumer tDCS market and relevant laws and regulations. In the five main sections of this manuscript, I take into account (a) the history of the do-it-yourself tDCS movement and the subsequent emergence of direct-to-consumer devices; (b) the statutory language of the Federal Food, Drug and Cosmetic Act and how the definition of a medical device—which focuses on the intended use of the device rather than its mechanism of action—is of paramount importance for discussions of consumer tDCS device regulation; (c) how both the Food and Drug Administration (FDA) and courts have understood the FDA's jurisdiction over medical devices in cases where the meaning of ‘intended use’ has been challenged; (d) an analysis of consumer tDCS regulatory enforcement action to-date; and (e) the multiple US authorities, other than the FDA, that can regulate consumer brain stimulation devices. Taken together, this paper demonstrates that rather than a ‘regulatory gap,’ there are multiple, distinct pathways by which consumer tDCS can be regulated in the United States. PMID:27774217

A single session of prefrontal cortex transcranial direct current stimulation does not modulate implicit task sequence learning and consolidation.

PubMed

Savic, Branislav; Müri, René; Meier, Beat

Transcranial direct current stimulation (tDCS) is assumed to affect cortical excitability and dependent on the specific stimulation conditions either to increase or decrease learning. The purpose of this study was to modulate implicit task sequence learning with tDCS. As cortico-striatal loops are critically involved in implicit task sequence learning, tDCS was applied above the dorsolateral prefrontal cortex (DLPFC). In Experiment 1, anodal, cathodal, or sham tDCS was applied before the start of the sequence learning task. In Experiment 2, stimulation was applied during the sequence learning task. Consolidation of learning was assessed after 24 h. The results of both experiments showed that implicit task sequence learning occurred consistently but it was not modulated by different tDCS conditions. Similarly, consolidation measured after a 24 h-interval including sleep was also not affected by stimulation. These results indicate that a single session of DLPFC tDCS is not sufficient to modulate implicit task sequence learning. This study adds to the accumulating evidence that tDCS may not be as effective as originally thought. Copyright © 2017 Elsevier Inc. All rights reserved.

Modulation of Perception or Emotion? A Scoping Review of Tinnitus Neuromodulation Using Transcranial Direct Current Stimulation.

PubMed

Shekhawat, Giriraj Singh; Stinear, Cathy M; Searchfield, Grant D

2015-10-01

Tinnitus is the phantom perception of sound and can have negative effect on the quality of life. Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation technique, which can increase or decrease the cortical excitability in the brain region to which it is applied. tDCS has been used for tinnitus research since 2006. To investigate whether tDCS affects tinnitus perception, related emotion, or both, and the potential implications for tinnitus management. A scoping review was undertaken using the methods proposed by Arksey and O'Malley. After initial consideration of title relevance and reading abstracts, 15 studies were included in this review. The data from these studies were charted to investigate the impact of tDCS on tinnitus perception and emotions. tDCS results in transient suppression of tinnitus loudness and annoyance; however, it does not lead to long-term impact on tinnitus related emotion. Local stimulation of different sites of stimulation (left temporoparietal area, dorsolateral prefrontal cortex, and auditory cortex) might modulate tinnitus perception (loudness) and emotions differently; however, further research is needed to explore this hypothesis. This review has identified aspects of methodologies that require attention in upcoming tinnitus and tDCS trials to offer better insights. tDCS is an effective research tool for transient tinnitus neuromodulation. However, efforts should be invested in designing clinical trials using local and multiple sites of stimulation, optimized parameters, and objective outcome measures before it can be translated in to a clinical tool for tinnitus management. © The Author(s) 2015.

Anodal Transcranial Direct Current Stimulation Does Not Facilitate Dynamic Balance Task Learning in Healthy Old Adults

PubMed Central

Kaminski, Elisabeth; Hoff, Maike; Rjosk, Viola; Steele, Christopher J.; Gundlach, Christopher; Sehm, Bernhard; Villringer, Arno; Ragert, Patrick

2017-01-01

Older adults frequently experience a decrease in balance control that leads to increased numbers of falls, injuries and hospitalization. Therefore, evaluating older adults’ ability to maintain balance and examining new approaches to counteract age-related decline in balance control is of great importance for fall prevention and healthy aging. Non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) have been shown to beneficially influence motor behavior and motor learning. In the present study, we investigated the influence of tDCS applied over the leg area of the primary motor cortex (M1) on balance task learning of healthy elderly in a dynamic balance task (DBT). In total, 30 older adults were enrolled in a cross-sectional, randomized design including two consecutive DBT training sessions. Only during the first DBT session, either 20 min of anodal tDCS (a-tDCS) or sham tDCS (s-tDCS) were applied and learning improvement was compared between the two groups. Our data showed that both groups successfully learned to perform the DBT on both training sessions. Interestingly, between-group analyses revealed no difference between the a-tDCS and the s-tDCS group regarding their level of task learning. These results indicate that the concurrent application of tDCS over M1 leg area did not elicit DBT learning enhancement in our study cohort. However, a regression analysis revealed that DBT performance can be predicted by the kinematic profile of the movement, a finding that may provide new insights for individualized approaches of treating balance and gait disorders. PMID:28197085

Use of functional near-infrared spectroscopy to monitor cortical plasticity induced by transcranial direct current stimulation

NASA Astrophysics Data System (ADS)

Khan, Bilal; Hervey, Nathan; Stowe, Ann; Hodics, Timea; Alexandrakis, George

2013-03-01

Electrical stimulation of the human cortex in conjunction with physical rehabilitation has been a valuable approach in facilitating the plasticity of the injured brain. One such method is transcranial direct current stimulation (tDCS) which is a non-invasive method to elicit neural stimulation by delivering current through electrodes placed on the scalp. In order to better understand the effects tDCS has on cortical plasticity, neuroimaging techniques have been used pre and post tDCS stimulation. Recently, neuroimaging methods have discovered changes in resting state cortical hemodynamics after the application of tDCS on human subjects. However, analysis of the cortical hemodynamic activity for a physical task during and post tDCS stimulation has not been studied to our knowledge. A viable and sensitive neuroimaging method to map changes in cortical hemodynamics during activation is functional near-infrared spectroscopy (fNIRS). In this study, the cortical activity during an event-related, left wrist curl task was mapped with fNIRS before, during, and after tDCS stimulation on eight healthy adults. Along with the fNIRS optodes, two electrodes were placed over the sensorimotor hand areas of both brain hemispheres to apply tDCS. Changes were found in both resting state cortical connectivity and cortical activation patterns that occurred during and after tDCS. Additionally, changes to surface electromyography (sEMG) measurements of the wrist flexor and extensor of both arms during the wrist curl movement, acquired concurrently with fNIRS, were analyzed and related to the transient cortical plastic changes induced by tDCS.

Effects of an NMDA antagonist on the auditory mismatch negativity response to transcranial direct current stimulation.

PubMed

Impey, Danielle; de la Salle, Sara; Baddeley, Ashley; Knott, Verner

2017-05-01

Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which uses a weak constant current to alter cortical excitability and activity temporarily. tDCS-induced increases in neuronal excitability and performance improvements have been observed following anodal stimulation of brain regions associated with visual and motor functions, but relatively little research has been conducted with respect to auditory processing. Recently, pilot study results indicate that anodal tDCS can increase auditory deviance detection, whereas cathodal tDCS decreases auditory processing, as measured by a brain-based event-related potential (ERP), mismatch negativity (MMN). As evidence has shown that tDCS lasting effects may be dependent on N-methyl-D-aspartate (NMDA) receptor activity, the current study investigated the use of dextromethorphan (DMO), an NMDA antagonist, to assess possible modulation of tDCS's effects on both MMN and working memory performance. The study, conducted in 12 healthy volunteers, involved four laboratory test sessions within a randomised, placebo and sham-controlled crossover design that compared pre- and post-anodal tDCS over the auditory cortex (2 mA for 20 minutes to excite cortical activity temporarily and locally) and sham stimulation (i.e. device is turned off) during both DMO (50 mL) and placebo administration. Anodal tDCS increased MMN amplitudes with placebo administration. Significant increases were not seen with sham stimulation or with anodal stimulation during DMO administration. With sham stimulation (i.e. no stimulation), DMO decreased MMN amplitudes. Findings from this study contribute to the understanding of underlying neurobiological mechanisms mediating tDCS sensory and memory improvements.

Anodal Transcranial Direct Current Stimulation Does Not Facilitate Dynamic Balance Task Learning in Healthy Old Adults.

PubMed

Kaminski, Elisabeth; Hoff, Maike; Rjosk, Viola; Steele, Christopher J; Gundlach, Christopher; Sehm, Bernhard; Villringer, Arno; Ragert, Patrick

2017-01-01

Older adults frequently experience a decrease in balance control that leads to increased numbers of falls, injuries and hospitalization. Therefore, evaluating older adults' ability to maintain balance and examining new approaches to counteract age-related decline in balance control is of great importance for fall prevention and healthy aging. Non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) have been shown to beneficially influence motor behavior and motor learning. In the present study, we investigated the influence of tDCS applied over the leg area of the primary motor cortex (M1) on balance task learning of healthy elderly in a dynamic balance task (DBT). In total, 30 older adults were enrolled in a cross-sectional, randomized design including two consecutive DBT training sessions. Only during the first DBT session, either 20 min of anodal tDCS (a-tDCS) or sham tDCS (s-tDCS) were applied and learning improvement was compared between the two groups. Our data showed that both groups successfully learned to perform the DBT on both training sessions. Interestingly, between-group analyses revealed no difference between the a-tDCS and the s-tDCS group regarding their level of task learning. These results indicate that the concurrent application of tDCS over M1 leg area did not elicit DBT learning enhancement in our study cohort. However, a regression analysis revealed that DBT performance can be predicted by the kinematic profile of the movement, a finding that may provide new insights for individualized approaches of treating balance and gait disorders.

Electrophysiological and behavioral effects of frontal transcranial direct current stimulation on cognitive fatigue in multiple sclerosis.

PubMed

Fiene, Marina; Rufener, Katharina S; Kuehne, Maria; Matzke, Mike; Heinze, Hans-Jochen; Zaehle, Tino

2018-03-01

Fatigue is one of the most common and debilitating symptoms affecting patients with multiple sclerosis (MS). Sustained cognitive effort induces cognitive fatigue, operationalized as subjective exhaustion and fatigue-related objective alertness decrements with time-on-task. During prolonged cognitive testing, MS patients show increased simple reaction times (RT) accompanied by lower amplitudes and prolonged latencies of the P300 event-related potential. Previous studies suggested a major role of structural and functional abnormalities in the frontal cortex including a frontal hypo-activation in fatigue pathogenesis. In the present study we investigated the neuromodulatory effect of transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) on objective measures of fatigue-related decrements in cognitive performance in MS patients. P300 during an auditory oddball task and simple reaction times in an alertness test were recorded at baseline, during and after stimulation. Compared to sham, anodal tDCS caused an increase in P300 amplitude that persisted after the end of stimulation and eliminated the fatigue-related increase in RT over the course of a testing session. Our findings demonstrate that anodal tDCS over the left DLPFC can counteract performance decrements associated with fatigue thereby leading to an improvement in the patient's ability to cope with sustained cognitive demands. This provides causal evidence for the functional relevance of the left DLPFC in fatigue pathophysiology. The results indicate that tDCS-induced modulations of frontal activity can be an effective therapeutic option for the treatment of fatigue-related declines in cognitive performance in MS patients.

Anodal Transcranial Direct Current Stimulation Shows Minimal, Measure-Specific Effects on Dynamic Postural Control in Young and Older Adults: A Double Blind, Sham-Controlled Study.

PubMed

Craig, Chesney E; Doumas, Michail

2017-01-01

We investigated whether stimulating the cerebellum and primary motor cortex (M1) using transcranial direct current stimulation (tDCS) could affect postural control in young and older adults. tDCS was employed using a double-blind, sham-controlled design, in which young (aged 18-35) and older adults (aged 65+) were assessed over three sessions, one for each stimulatory condition-M1, cerebellar and sham. The effect of tDCS on postural control was assessed using a sway-referencing paradigm, which induced platform rotations in proportion to the participant's body sway, thus assessing sensory reweighting processes. Task difficulty was manipulated so that young adults experienced a support surface that was twice as compliant as that of older adults, in order to minimise baseline age differences in postural sway. Effects of tDCS on postural control were assessed during, immediately after and 30 minutes after tDCS. Additionally, the effect of tDCS on corticospinal excitability was measured by evaluating motor evoked potentials using transcranial magnetic stimulation immediately after and 30 minutes after tDCS. Minimal effects of tDCS on postural control were found in the eyes open condition only, and this was dependent on the measure assessed and age group. For young adults, stimulation had only offline effects, as cerebellar stimulation showed higher mean power frequency (MPF) of sway 30 minutes after stimulation. For older adults, both stimulation conditions delayed the increase in sway amplitude witnessed between blocks one and two until stimulation was no longer active. In conclusion, despite tDCS' growing popularity, we would caution researchers to consider carefully the type of measures assessed and the groups targeted in tDCS studies of postural control.

Transcranial direct current stimulation (tDCS) Paired with massed practice training to promote adaptive plasticity and motor recovery in chronic incomplete tetraplegia: a pilot study.

PubMed

Potter-Baker, Kelsey A; Janini, Daniel P; Lin, Yin-Liang; Sankarasubramanian, Vishwanath; Cunningham, David A; Varnerin, Nicole M; Chabra, Patrick; Kilgore, Kevin L; Richmond, Mary Ann; Frost, Frederick S; Plow, Ela B

2017-08-07

Objective Our goal was to determine if pairing transcranial direct current stimulation (tDCS) with rehabilitation for two weeks could augment adaptive plasticity offered by these residual pathways to elicit longer-lasting improvements in motor function in incomplete spinal cord injury (iSCI). Design Longitudinal, randomized, controlled, double-blinded cohort study. Setting Cleveland Clinic Foundation, Cleveland, Ohio, USA. Participants Eight male subjects with chronic incomplete motor tetraplegia. Interventions Massed practice (MP) training with or without tDCS for 2 hrs, 5 times a week. Outcome Measures We assessed neurophysiologic and functional outcomes before, after and three months following intervention. Neurophysiologic measures were collected with transcranial magnetic stimulation (TMS). TMS measures included excitability, representational volume, area and distribution of a weaker and stronger muscle motor map. Functional assessments included a manual muscle test (MMT), upper extremity motor score (UEMS), action research arm test (ARAT) and nine hole peg test (NHPT). Results We observed that subjects receiving training paired with tDCS had more increased strength of weak proximal (15% vs 10%), wrist (22% vs 10%) and hand (39% vs. 16%) muscles immediately and three months after intervention compared to the sham group. Our observed changes in muscle strength were related to decreases in strong muscle map volume (r=0.851), reduced weak muscle excitability (r=0.808), a more focused weak muscle motor map (r=0.675) and movement of weak muscle motor map (r=0.935). Conclusion Overall, our results encourage the establishment of larger clinical trials to confirm the potential benefit of pairing tDCS with training to improve the effectiveness of rehabilitation interventions for individuals with SCI. Trial Registration NCT01539109.

Transcranial stimulability of phosphenes by long lightning electromagnetic pulses

NASA Astrophysics Data System (ADS)

Peer, J.; Kendl, A.

2010-06-01

The electromagnetic pulses of rare long (order of seconds) repetitive lightning discharges near strike point (order of 100 m) are analyzed and compared to magnetic fields applied in standard clinical transcranial magnetic stimulation (TMS) practice. It is shown that the time-varying lightning magnetic fields and locally induced electric fields are in the same order of magnitude and frequency as those established in TMS experiments to study stimulated perception phenomena, like magnetophosphenes. Lightning electromagnetic pulse induced transcranial magnetic stimulation of phosphenes in the visual cortex is concluded to be a plausible interpretation of a large class of reports on luminous perceptions during thunderstorms.

Transcranial Photoacoustic Measurements of Cold-Injured Brains in Rats

NASA Astrophysics Data System (ADS)

Ueda, Yoshinori; Sato, Shunichi; Hasegawa, Makoto; Nawashiro, Hiroshi; Saitoh, Daizoh; Shima, Katsuji; Ashida, Hiroshi; Obara, Minoru

2005-09-01

We performed transcranial photoacoustic measurements of cold-injured brains in rats. Before inducing injury, a signal peak was observed at two locations corresponding to the surfaces of the skull and brain, while after injury, a third peak appeared at a location corresponding to the back surface of the skull; the third peak was found to be caused by subdural hematoma. The signal peak for the brain surface shifted to a deeper region with elapse of time after injury, indicating deformation of the brain. These findings suggest that small hemorrhage and morphological change of the brain can be transcranially detected by photoacoustic measurement.

Preliminary Evidence of the Effects of High-frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Swallowing Functions in Post-Stroke Individuals with Chronic Dysphagia

ERIC Educational Resources Information Center

Cheng, Ivy K. Y.; Chan, Karen M. K.; Wong, C. S.; Cheung, Raymond T. F.

2015-01-01

Background: There is growing evidence of potential benefits of repetitive transcranial magnetic stimulation (rTMS) in the rehabilitation of dysphagia. However, the site and frequency of stimulation for optimal effects are not clear. Aims: The aim of this pilot study is to investigate the short-term effects of high-frequency 5 Hz rTMS applied to…

The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia

PubMed Central

Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P.; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin

2016-01-01

Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia. PMID:26763954

The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia.

PubMed

Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin

2016-01-14

Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia.

Tracking the Effect of Cathodal Transcranial Direct Current Stimulation on Cortical Excitability and Connectivity by Means of TMS-EEG

PubMed Central

Varoli, Erica; Pisoni, Alberto; Mattavelli, Giulia C.; Vergallito, Alessandra; Gallucci, Alessia; Mauro, Lilia D.; Rosanova, Mario; Bolognini, Nadia; Vallar, Giuseppe; Romero Lauro, Leonor J.

2018-01-01

Transcranial direct current stimulation (tDCS) is increasingly used in both research and therapeutic settings, but its precise mechanisms remain largely unknown. At a neuronal level, tDCS modulates cortical excitability by shifting the resting membrane potential in a polarity-dependent way: anodal stimulation increases the spontaneous firing rate, while cathodal decreases it. However, the neurophysiological underpinnings of anodal/cathodal tDCS seem to be different, as well as their behavioral effect, in particular when high order areas are involved, compared to when motor or sensory brain areas are targeted. Previously, we investigated the effect of anodal tDCS on cortical excitability, by means of a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG). Results showed a diffuse rise of cortical excitability in a bilateral fronto-parietal network. In the present study, we tested, with the same paradigm, the effect of cathodal tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 10 min of cathodal or sham tDCS over the right PPC, while recording HD-EEG. Indexes of global and local cortical excitability were obtained both at sensors and cortical sources level. At sensors, global and local mean field power (GMFP and LMFP) were computed for three temporal windows (0–50, 50–100, and 100–150 ms), on all channels (GMFP), and in four different clusters of electrodes (LMFP, left and right, in frontal and parietal regions). After source reconstruction, Significant Current Density was computed at the global level, and for four Broadmann's areas (left/right BA 6 and 7). Both sensors and cortical sources results converge in showing no differences during and after cathodal tDCS compared to pre-stimulation sessions, both at global and local level. The same holds for sham tDCS. These data highlight an asymmetric impact of anodal and cathodal stimulation on cortical excitability, with

Effects of transcranial direct current stimulation on language improvement and cortical activation in nonfluent variant primary progressive aphasia.

PubMed

Wang, Jie; Wu, Dongyu; Chen, Yan; Yuan, Ying; Zhang, Meikui

2013-08-09

We investigate the effects of transcranial direct current stimulation (tDCS) on language improvement and cortical activation in nonfluent variant primary progressive aphasia (nfvPPA). A 67-year-old woman diagnosed as nfvPPA received sham-tDCS for 5 days over the left posterior perisylvian region (PPR) in the morning and over left Broca's area in the afternoon in Phases A1 and A2, and tDCS for 5 days with an anodal electrode over the left PPR in the morning and over left Broca's area in the afternoon in Phases B1 and B2. Auditory word comprehension, picture naming, oral word reading and word repetition subtests of the Psycholinguistic Assessment in Chinese Aphasia (PACA) were administered before and after each phase. The EEG nonlinear index of approximate entropy (ApEn) was calculated before Phase A1, and after Phases B1 and B2. Our findings revealed that the patient improved greatly in the four subtests after A-tDCS and ApEn indices increased in stimulated areas and non-stimulated areas. We demonstrated that anodal tDCS over the left PPR and Broca's area can improve language performance of nfvPPA. tDCS may be used as an alternative therapeutic tool for PPA. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Cognitive Training and Transcranial Direct Current Stimulation for Mild Cognitive Impairment in Parkinson's Disease: A Randomized Controlled Trial

PubMed Central

Gasson, Natalie; Johnson, Andrew R.; Booth, Leon; Loftus, Andrea M.

2018-01-01

This study examined whether standard cognitive training, tailored cognitive training, transcranial direct current stimulation (tDCS), standard cognitive training + tDCS, or tailored cognitive training + tDCS improved cognitive function and functional outcomes in participants with PD and mild cognitive impairment (PD-MCI). Forty-two participants with PD-MCI were randomized to one of six groups: (1) standard cognitive training, (2) tailored cognitive training, (3) tDCS, (4) standard cognitive training + tDCS, (5) tailored cognitive training + tDCS, or (6) a control group. Interventions lasted 4 weeks, with cognitive and functional outcomes measured at baseline, post-intervention, and follow-up. The trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR: 12614001039673). While controlling for moderator variables, Generalized Linear Mixed Models (GLMMs) showed that when compared to the control group, the intervention groups demonstrated variable statistically significant improvements across executive function, attention/working memory, memory, language, activities of daily living (ADL), and quality of life (QOL; Hedge's g range = 0.01 to 1.75). More outcomes improved for the groups that received standard or tailored cognitive training combined with tDCS. Participants with PD-MCI receiving cognitive training (standard or tailored) or tDCS demonstrated significant improvements on cognitive and functional outcomes, and combining these interventions provided greater therapeutic effects. PMID:29780572

Transcranial direct current stimulation in post stroke aphasia and primary progressive aphasia: Current knowledge and future clinical applications.

PubMed

Sebastian, Rajani; Tsapkini, Kyrana; Tippett, Donna C

2016-06-13

The application of transcranial direct current stimulation (tDCS) in chronic post stroke aphasia is documented in a substantial literature, and there is some new evidence that tDCS can augment favorable language outcomes in primary progressive aphasia. Anodal tDCS is most often applied to the left hemisphere language areas to increase cortical excitability (increase the threshold of activation) and cathodal tDCS is most often applied to the right hemisphere homotopic areas to inhibit over activation in contralesional right homologues of language areas. Outcomes usually are based on neuropsychological and language test performance, following a medical model which emphasizes impairment of function, rather than a model which emphasizes functional communication. In this paper, we review current literature of tDCS as it is being used as a research tool, and discuss future implementation of tDCS as an adjuvant treatment to behavioral speech-language pathology intervention. We review literature describing non-invasive brain stimulation, the mechanism of tDCS, and studies of tDCS in aphasia and neurodegenerative disorders. We discuss future clinical applications. tDCS is a promising adjunct to traditional speech-language pathology intervention to address speech-language deficits after stroke and in the neurodegenerative disease, primary progressive aphasia. Limited data are available regarding how performance on these types of specific tasks translates to functional communication outcomes.

Multiple sessions of transcranial direct current stimulation and upper extremity rehabilitation in stroke: A review and meta-analysis.

PubMed

Tedesco Triccas, L; Burridge, J H; Hughes, A M; Pickering, R M; Desikan, M; Rothwell, J C; Verheyden, G

2016-01-01

To systematically review the methodology in particular treatment options and outcomes and the effect of multiple sessions of transcranial direct current stimulation (tDCS) with rehabilitation programmes for upper extremity recovery post stroke. A search was conducted for randomised controlled trials involving tDCS and rehabilitation for the upper extremity in stroke. Quality of included studies was analysed using the Modified Downs and Black form. The extent of, and effect of variation in treatment parameters such as anodal, cathodal and bi-hemispheric tDCS on upper extremity outcome measures of impairment and activity were analysed using meta-analysis. Nine studies (371 participants with acute, sub-acute and chronic stroke) were included. Different methodologies of tDCS and upper extremity intervention, outcome measures and timing of assessments were identified. Real tDCS combined with rehabilitation had a small non-significant effect of +0.11 (p=0.44) and +0.24 (p=0.11) on upper extremity impairments and activities at post-intervention respectively. Various tDCS methods have been used in stroke rehabilitation. The evidence so far is not statistically significant, but is suggestive of, at best, a small beneficial effect on upper extremity impairment. Future research should focus on which patients and rehabilitation programmes are likely to respond to different tDCS regimes. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Effects of Navigated Repetitive Transcranial Magnetic Stimulation After Stroke.

PubMed

Chervyakov, Alexander V; Poydasheva, Alexandra G; Lyukmanov, Roman H; Suponeva, Natalia A; Chernikova, Ludmila A; Piradov, Michael A; Ustinova, Ksenia I

2018-03-01

The purpose of this study was to test the effects of navigated repetitive transcranial magnetic stimulation, delivered in different modes, on motor impairments and functional limitations after stroke. The study sample included 42 patients (58.5 ± 10.7 years; 26 males) who experienced a single unilateral stroke (1-12 months previously) in the area of the middle cerebral artery. Patients completed a course of conventional rehabilitation, together with 10 sessions of navigated repetitive transcranial magnetic stimulation or sham stimulation. Stimulation was scheduled five times a week over two consecutive weeks in an inpatient clinical setting. Patients were randomly assigned to one of four groups and received sham stimulation (n = 10), low-frequency (1-Hz) stimulation of the nonaffected hemisphere (n = 11), high-frequency (10-Hz) stimulation of the affected hemisphere (n = 13), or sequential combination of low- and high-frequency stimulations (n = 8). Participants were evaluated before and after stimulation with clinical tests, including the arm and hand section of the Fugl-Meyer Assessment Scale, modified Ashworth Scale of Muscle Spasticity, and Barthel Index of Activities of Daily Living. Participants in the three groups receiving navigated repetitive transcranial magnetic stimulation showed improvements in arm and hand functions on the Fugl-Meyer Stroke Assessment Scale. Ashworth Scale of Muscle Spasticity and Barthel Index scores were significantly reduced in groups receiving low- or high-frequency stimulation alone. Including navigated repetitive transcranial magnetic stimulation in a conventional rehabilitation program positively influenced motor and functional recovery in study participants, demonstrating the clinical potential of the method. The results of this study will be used for designing a large-scale clinical trial.

Physiological and modeling evidence for focal transcranial electrical brain stimulation in humans: A basis for high-definition tDCS

PubMed Central

Edwards, Dylan; Cortes, Mar; Datta, Abhishek; Minhas, Preet; Wassermann, Eric M.; Bikson, Marom

2015-01-01

Transcranial Direct Current Stimulation (tDCS) is a non-invasive, low-cost, well-tolerated technique producing lasting modulation of cortical excitability. Behavioral and therapeutic outcomes of tDCS are linked to the targeted brain regions, but there is little evidence that current reaches the brain as intended. We aimed to: (1) validate a computational model for estimating cortical electric fields in human transcranial stimulation, and (2) assess the magnitude and spread of cortical electric field with a novel High-Definition tDCS (HD-tDCS) scalp montage using a 4×1-Ring electrode configuration. In three healthy adults, Transcranial Electrical Stimulation (TES) over primary motor cortex (M1) was delivered using the 4×1 montage (4× cathode, surrounding a single central anode; montage radius ~3 cm) with sufficient intensity to elicit a discrete muscle twitch in the hand. The estimated current distribution in M1 was calculated using the individualized MRI-based model, and compared with the observed motor response across subjects. The response magnitude was quantified with stimulation over motor cortex as well as anterior and posterior to motor cortex. In each case the model data were consistent with the motor response across subjects. The estimated cortical electric fields with the 4×1 montage were compared (area, magnitude, direction) for TES and tDCS in each subject. We provide direct evidence in humans that TES with a 4×1-Ring configuration can activate motor cortex and that current does not substantially spread outside the stimulation area. Computational models predict that both TES and tDCS waveforms using the 4×1-Ring configuration generate electric fields in cortex with comparable gross current distribution, and preferentially directed normal (inward) currents. The agreement of modeling and experimental data for both current delivery and focality support the use of the HD-tDCS 4×1-Ring montage for cortically targeted neuromodulation. PMID:23370061

Probing phase- and frequency-dependent characteristics of cortical interneurons using combined transcranial alternating current stimulation and transcranial magnetic stimulation.

PubMed

Hussain, Sara J; Thirugnanasambandam, Nivethida

2017-06-01

Paired-pulse transcranial magnetic stimulation (TMS) and peripheral stimulation combined with TMS can be used to study cortical interneuronal circuitry. By combining these procedures with concurrent transcranial alternating current stimulation (tACS), Guerra and colleagues recently showed that different cortical interneuronal populations are differentially modulated by the phase and frequency of tACS-imposed oscillations (Guerra A, Pogosyan A, Nowak M, Tan H, Ferreri F, Di Lazzaro V, Brown P. Cerebral Cortex 26: 3977-2990, 2016). This work suggests that different cortical interneuronal populations can be characterized by their phase and frequency dependency. Here we discuss how combining TMS and tACS can reveal the frequency at which cortical interneuronal populations oscillate, the neuronal origins of behaviorally relevant cortical oscillations, and how entraining cortical oscillations could potentially treat brain disorders. Copyright © 2017 the American Physiological Society.

Transcranial direct-current stimulation (tDCS) for bipolar depression: A systematic review and meta-analysis.

PubMed

Dondé, Clément; Amad, Ali; Nieto, Isabel; Brunoni, André Russowsky; Neufeld, Nicholas H; Bellivier, Frank; Poulet, Emmanuel; Geoffroy, Pierre-Alexis

2017-08-01

Bipolar disorder (BD) is a severe and recurrent brain disorder that can manifest in manic or depressive episodes. Transcranial Direct Current Stimulation (tDCS) has been proposed as a novel therapeutic modality for patients experiencing bipolar depression, for which standard treatments are often inefficient. While several studies have been conducted in this patient group, there has been no systematic review or meta-analysis that specifically examines bipolar depression. We aimed to address this gap in the literature and evaluated the efficacy and tolerability of tDCS in patients fulfilling DSM-IV-TR criteria for BD I, II, or BD not otherwise specified (NOS). We systematically searched the literature from April 2002 to November 2016 to identify relevant publications for inclusion in our systematic review and meta-analysis. Effect sizes for depression rating-scale scores were expressed as the standardized mean difference (SMD) before and after tDCS. Thirteen of 382 identified studies met eligibility criteria for our systematic review. The meta-analysis included 46 patients from 7 studies with depression rating-scale scores pre- and post-tDCS. Parameters of tDCS procedures were heterogeneous. Depression scores decreased significantly with a medium effect size after acute-phase of treatment (SMD 0.71 [0.25-1.18], z=3.00, p=0.003) and at the furthest endpoint (SMD 1.27 [0.57-1.97], z=3.57, p=0.0004). Six cases of affective switching under tDCS treatment protocols were observed. Depressive symptoms respond to tDCS in patients with BD. Additional studies, and particularly randomized controlled trials, are needed to clarify the effectiveness of tDCS in bipolar depression, the frequency of tDCS-emergent hypomania/mania, and which tDCS modalities are most efficient. Copyright © 2017 Elsevier Inc. All rights reserved.

Motor/Prefrontal Transcranial Direct Current Stimulation (tDCS) Following Lumbar Surgery Reduces Postoperative Analgesia Use.

PubMed

Glaser, John; Reeves, Scott T; Stoll, William David; Epperson, Thomas I; Hilbert, Megan; Madan, Alok; George, Mark S; Borckardt, Jeffrey J

2016-05-01

Randomized, controlled pilot trial. The present study is the first randomized, double-blind, sham-controlled pilot clinical trial of transcranial direct current stimulation (tDCS) for pain and patient-controlled analgesia (PCA) opioid usage among patients receiving spine surgery. Lumbar spinal surgeries are common, and while pain is often a complaint that precedes surgical intervention, the procedures themselves are associated with considerable postoperative pain lasting days to weeks. Adequate postoperative pain control is an important factor in determining recovery and new analgesic strategies are needed that can be used adjunctively to existing strategies potentially to reduce reliance on opioid analgesia. Several novel brain stimulation technologies including tDCS are beginning to demonstrate promise as treatments for a variety of pain conditions. Twenty-seven patients undergoing lumbar spine procedures at Medical University of South Carolina were randomly assigned to receive four 20-minute sessions of real or sham tDCS during their postsurgical hospital stay. Patient-administered hydromorphone usage was tracked along with numeric rating scale pain ratings. The effect of tDCS on the slope of the cumulative PCA curve was significant (P < 0.001) and tDCS was associated with a 23% reduction in PCA usage. In the real tDCS group a 31% reduction was observed in pain-at-its-least ratings from admission to discharge (P = 0.027), but no other changes in numeric rating scale pain ratings were significant in either group. The present pilot trial is the first study to demonstrate an opioid sparing effect of tDCS after spine surgical procedures. Although this was a small pilot trial in a heterogeneous sample of spinal surgery patients, a moderate effect-size was observed for tDCS, suggesting that future work in this area is warranted. 2.

Effects of Transcranial Direct Current Stimulation (tDCS) on Pain Distress Tolerance: A Preliminary Study.

PubMed

Mariano, Timothy Y; van't Wout, Mascha; Jacobson, Benjamin L; Garnaat, Sarah L; Kirschner, Jason L; Rasmussen, Steven A; Greenberg, Benjamin D

2015-08-01

Pain remains a critical medical challenge. Current treatments target nociception without addressing affective symptoms. Medically intractable pain is sometimes treated with cingulotomy or deep brain stimulation to increase tolerance of pain-related distress. Transcranial direct current stimulation (tDCS) may noninvasively modulate cortical areas related to sensation and pain representations. The present study aimed to test the hypothesis that cathodal ("inhibitory") stimulation targeting left dorsal anterior cingulate cortex (dACC) would increase tolerance to distress from acute painful stimuli vs anodal stimulation. Forty healthy volunteers received both anodal and cathodal stimulation. During stimulation, we measured pain distress tolerance with three tasks: pressure algometer, cold pressor, and breath holding. We measured pain intensity with a visual-analog scale before and after each task. Mixed ANOVA revealed that mean cold pressor tolerance tended to be higher with cathodal vs anodal stimulation (P = 0.055) for participants self-completing the task. Pressure algometer (P = 0.81) and breath holding tolerance (P = 0.19) did not significantly differ. The pressure algometer exhibited a statistically significant order effect irrespective of stimulation polarity (all P < 0.008). Pain intensity ratings increased acutely after cold pressor and pressure algometer tasks (both P < 0.01), but not after breath holding (P = 0.099). Cold pressor pain ratings tended to rise less after cathodal vs anodal tDCS (P = 0.072). Although our primary results were nonsignificant, there is a preliminary suggestion that cathodal tDCS targeting left dACC may increase pain distress tolerance to cold pressor. Pressure algometer results are consistent with task-related sensitization. Future studies are needed to refine this novel approach for pain neuromodulation. Wiley Periodicals, Inc.

Does anodal transcranial direct current stimulation modulate sensory perception and pain? A meta-analysis study.

PubMed

Vaseghi, B; Zoghi, M; Jaberzadeh, S

2014-09-01

The primary aim of this systematic review was to evaluate the effects of anodal transcranial direct current stimulation (a-tDCS) on sensory (STh) and pain thresholds (PTh) in healthy individuals and pain levels (PL) in patients with chronic pain. Electronic databases were searched for a-tDCS studies. Methodological quality was examined using the PEDro and Downs and Black (D&B) assessment tools. a-tDCS of the primary motor cortex (M1) increases both STh (P<0.005, with the effect size of 22.19%) and PTh (P<0.001, effect size of 19.28%). In addition, STh was increased by a-tDCS of the primary sensory cortex (S1) (P<0.05 with an effect size of 4.34). Likewise, PL decreased significantly in the patient group following application of a-tDCS to both the M1 and dorsolateral prefrontal cortex (DLPFC). The average decrease in visual analogue score was 14.9% and 19.3% after applying a-tDCS on the M1 and DLPFC. Moreover, meta-analysis showed that in all subgroups (except a-tDCS of S1) active a-tDCS and sham stimulation produced significant differences. This review provides evidence for the effectiveness of a-tDCS in increasing STh/PTh in healthy group and decreasing PL in patients. However, due to small sample sizes in the included studies, our results should be interpreted cautiously. Given the level of blinding did not considered in inclusion criteria, the result of current study should be interpreted with caution. Site of stimulation should have a differential effect over pain relief. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Transcranial Direct Current Stimulation of Frontal Cortex Decreases Performance on the WAIS-IV Intelligence Test

PubMed Central

Sellers, Kristin K.; Mellin, Juliann M.; Lustenberger, Caroline M.; Boyle, Michael R.; Lee, Won Hee; Peterchev, Angel V.; Frohlich, Flavio

2015-01-01

Transcranial direct current stimulation (tDCS) modulates excitability of motor cortex. However, there is conflicting evidence about the efficacy of this non-invasive brain stimulation modality to modulate performance on cognitive tasks. Previous work has tested the effect of tDCS on specific facets of cognition and executive processing. However, no randomized, double-blind, sham-controlled study has looked at the effects of tDCS on a comprehensive battery of cognitive processes. The objective of this study was to test if tDCS had an effect on performance on a comprehensive assay of cognitive processes, a standardized intelligence quotient (IQ) test. The study consisted of two substudies and followed a double-blind, between-subjects, sham-controlled design. In total, 41 healthy adult participants completed the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV) as a baseline measure. At least one week later, participants in substudy 1 received either bilateral tDCS (anodes over both F4 and F3, cathode over Cz, 2mA at each anode for 20 minutes) or active sham tDCS (2mA for 40 seconds), and participants in substudy 2 received either right or left tDCS (anode over either F4 or F3, cathode over Cz, 2mA for 20 minutes). In both studies, the WAIS-IV was immediately administered following stimulation to assess for performance differences induced by bilateral and unilateral tDCS. Compared to sham stimulation, right, left, and bilateral tDCS reduced improvement between sessions on Full Scale IQ and the Perceptual Reasoning Index. This demonstration that frontal tDCS selectively degraded improvement on specific metrics of the WAIS-IV raises important questions about the often proposed role of tDCS in cognitive enhancement. PMID:25934490

[Self-directed learning and academic background of 2010 to 2014 cohorts of medical students].

PubMed

Pérez-Villalobos, Cristhian E; Fasce-Henry, Eduardo A; Ortega-Bastidas, Javiera A; Ortiz-Moreira, Liliana E; Bastías-Vega, Nancy; Bustamante-Durán, Carolina E; Ibáñez-Gracia, Pilar; Márquez-Urrizola, Carolina G; Delgado-Rivera, Macarena; Glaría-López, Rocío

2017-07-01

The widespread growth of higher education is increasing the heterogeneity of university students in terms of socioeconomic characteristics, academic story and cultural background. Medical schools are not an exception of this phenomenon. To compare the academic background and self-directed learning behavior of students who entered to a public medial school between 2010 and 2014. A non-probabilistic sample of 527 medical students aged between 17 and 29 years (60% men), was studied. Their academic information was collected from the University data base; they answered the Self-directed learning readiness scale of Fisher. Students from the 2014 cohort had higher high school grades than their counterparts. The scores in mathematics of the Scholarship Aptitude Test (SAT) were higher in the cohorts of 2010 and 2011. Those of the sciences test were superior in the 2013 cohort. The 2014 cohort had the lower general score of self-directed learning behaviors. The lower SAT and self-directed learning scores of the students entering medical school in 2014, indicate the progressive increase in the heterogeneity of Medical students.

Transcranial direct current stimulation over multiple days enhances motor performance of a grip task.

PubMed

Fan, Julie; Voisin, Julien; Milot, Marie-Hélène; Higgins, Johanne; Boudrias, Marie-Hélène

2017-09-01

Recovery of handgrip is critical after stroke since it is positively related to upper limb function. To boost motor recovery, transcranial direct current stimulation (tDCS) is a promising, non-invasive brain stimulation technique for the rehabilitation of persons with stroke. When applied over the primary motor cortex (M1), tDCS has been shown to modulate neural processes involved in motor learning. However, no studies have looked at the impact of tDCS on the learning of a grip task in both stroke and healthy individuals. To assess the use of tDCS over multiple days to promote motor learning of a grip task using a learning paradigm involving a speed-accuracy tradeoff in healthy individuals. In a double-blinded experiment, 30 right-handed subjects (mean age: 22.1±3.3 years) participated in the study and were randomly assigned to an anodal (n=15) or sham (n=15) stimulation group. First, subjects performed the grip task with their dominant hand while following the pace of a metronome. Afterwards, subjects trained on the task, at their own pace, over 5 consecutive days while receiving sham or anodal tDCS over M1. After training, subjects performed de novo the metronome-assisted task. The change in performance between the pre and post metronome-assisted task was used to assess the impact of the grip task and tDCS on learning. Anodal tDCS over M1 had a significant effect on the speed-accuracy tradeoff function. The anodal tDCS group showed significantly greater improvement in performance (39.28±15.92%) than the sham tDCS group (24.06±16.35%) on the metronome-assisted task, t(28)=2.583, P=0.015 (effect size d=0.94). Anodal tDCS is effective in promoting grip motor learning in healthy individuals. Further studies are warranted to test its potential use for the rehabilitation of fine motor skills in stroke patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Against Strong Ethical Parity: Situated Cognition Theses and Transcranial Brain Stimulation.

PubMed

Heinrichs, Jan-Hendrik

2017-01-01

According to a prominent suggestion in the ethics of transcranial neurostimulation the effects of such devices can be treated as ethically on par with established, pre-neurotechnological alterations of the mind. This parity allegedly is supported by situated cognition theories showing how external devices can be part of a cognitive system. This article will evaluate this suggestion. It will reject the claim, that situated cognition theories support ethical parity. It will however point out another reason, why external carriers or modifications of the mental might come to be considered ethically on par with internal carriers. Section "Why Could There Be Ethical Parity between Neural Tissue and External Tools?" presents the ethical parity theses between external and internal carriers of the mind as well as neurotechnological alterations and established alterations. Section "Extended, Embodied, Embedded: Situated Cognition as a Relational Thesis" will elaborate the different situated cognition approaches and their relevance for ethics. It will evaluate, whether transcranial stimulation technologies are plausible candidates for situated cognition theses. Section "On the Ethical Relevance of Situated Cognition Theses" will discuss criteria for evaluating whether a cognitive tool is deeply embedded with a cognitive system and apply these criteria to transcranial brain stimulation technologies. Finally it will discuss the role diverse versions of situated cognition theory can play in the ethics of altering mental states, especially the ethics of transcranial brain stimulation technologies.

Quantitative Review Finds No Evidence of Cognitive Effects in Healthy Populations From Single-session Transcranial Direct Current Stimulation (tDCS).

PubMed

Horvath, Jared Cooney; Forte, Jason D; Carter, Olivia

2015-01-01

Over the last 15-years, transcranial direct current stimulation (tDCS), a relatively novel form of neuromodulation, has seen a surge of popularity in both clinical and academic settings. Despite numerous claims suggesting that a single session of tDCS can modulate cognition in healthy adult populations (especially working memory and language production), the paradigms utilized and results reported in the literature are extremely variable. To address this, we conduct the largest quantitative review of the cognitive data to date. Single-session tDCS data in healthy adults (18-50) from every cognitive outcome measure reported by at least two different research groups in the literature was collected. Outcome measures were divided into 4 broad categories: executive function, language, memory, and miscellaneous. To account for the paradigmatic variability in the literature, we undertook a three-tier analysis system; each with less-stringent inclusion criteria than the prior. Standard mean difference values with 95% CIs were generated for included studies and pooled for each analysis. Of the 59 analyses conducted, tDCS was found to not have a significant effect on any - regardless of inclusion laxity. This includes no effect on any working memory outcome or language production task. Our quantitative review does not support the idea that tDCS generates a reliable effect on cognition in healthy adults. Reasons for and limitations of this finding are discussed. This work raises important questions regarding the efficacy of tDCS, state-dependency effects, and future directions for this tool in cognitive research. Copyright © 2015 Elsevier Inc. All rights reserved.

Modulating activity in the prefrontal cortex changes decision-making for risky gains and losses: a transcranial direct current stimulation study.

PubMed

Ye, Hang; Chen, Shu; Huang, Daqiang; Wang, Siqi; Luo, Jun

2015-06-01

When making choices under uncertainty, people usually consider both the risks and benefits of each option. Previous studies have found that weighing of risks and benefits during decision-making involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC), but the causal effect of this network on risk decision-making has remained unclear. This experiment was based on a risk-measurement table designed to provide a direct measure of risk preference, with a weighted value of the choices (denoted as weighted risk aversion, WRA) as an index of the participant's degree of risk aversion. We studied whether bifrontal transcranial direct current stimulation (tDCS) applied over the right and left prefrontal cortex can change the balance of risky vs. safe responses under both gain frame and loss frame. A total of 60 volunteers performed risk tasks while receiving either anodal over the right with cathodal over the left DLPFC, anodal over the left with cathodal over the right DLPFC, or sham stimulation. The participants tended to choose more risky options in the gain frame and more safe options in the loss frame after the right anodal/left cathodal tDCS. We also found that right anodal/left cathodal tDCS significantly decreased the WRA values compared with those associated with sham stimulation. These findings extend the notion that DLPFC activity is critical for risk decision-making, indicating an asymmetric role of the right DLPFC in the gain frame vs. the loss frame of risk decision-making. Copyright © 2015 Elsevier B.V. All rights reserved.

Cortical inhibition and excitation by bilateral transcranial alternating current stimulation.

PubMed

Cancelli, Andrea; Cottone, Carlo; Zito, Giancarlo; Di Giorgio, Marina; Pasqualetti, Patrizio; Tecchio, Franca

2015-01-01

Transcranial electric stimulations (tES) with amplitude-modulated currents are promising tools to enhance neuromodulation effects. It is essential to select the correct cortical targets and inhibitory/excitatory protocols to reverse changes in specific networks. We aimed at assessing the dependence of cortical excitability changes on the current amplitude of 20 Hz transcranial alternating current stimulation (tACS) over the bilateral primary motor cortex. We chose two amplitude ranges of the stimulations, around 25 μA/cm2 and 63 μA/cm2 from peak to peak, with three values (at steps of about 2.5%) around each, to generate, respectively, inhibitory and excitatory effects of the primary motor cortex. We checked such changes online through transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs). Cortical excitability changes depended upon current density (p = 0.001). Low current densities decreased MEP amplitudes (inhibition) while high current densities increased them (excitation). tACS targeting bilateral homologous cortical areas can induce online inhibition or excitation as a function of the current density.

Anodal Transcranial Direct Current Stimulation Shows Minimal, Measure-Specific Effects on Dynamic Postural Control in Young and Older Adults: A Double Blind, Sham-Controlled Study

PubMed Central

Doumas, Michail

2017-01-01

We investigated whether stimulating the cerebellum and primary motor cortex (M1) using transcranial direct current stimulation (tDCS) could affect postural control in young and older adults. tDCS was employed using a double-blind, sham-controlled design, in which young (aged 18–35) and older adults (aged 65+) were assessed over three sessions, one for each stimulatory condition–M1, cerebellar and sham. The effect of tDCS on postural control was assessed using a sway-referencing paradigm, which induced platform rotations in proportion to the participant’s body sway, thus assessing sensory reweighting processes. Task difficulty was manipulated so that young adults experienced a support surface that was twice as compliant as that of older adults, in order to minimise baseline age differences in postural sway. Effects of tDCS on postural control were assessed during, immediately after and 30 minutes after tDCS. Additionally, the effect of tDCS on corticospinal excitability was measured by evaluating motor evoked potentials using transcranial magnetic stimulation immediately after and 30 minutes after tDCS. Minimal effects of tDCS on postural control were found in the eyes open condition only, and this was dependent on the measure assessed and age group. For young adults, stimulation had only offline effects, as cerebellar stimulation showed higher mean power frequency (MPF) of sway 30 minutes after stimulation. For older adults, both stimulation conditions delayed the increase in sway amplitude witnessed between blocks one and two until stimulation was no longer active. In conclusion, despite tDCS’ growing popularity, we would caution researchers to consider carefully the type of measures assessed and the groups targeted in tDCS studies of postural control. PMID:28099522

Transcranial Direct Current Stimulation to Enhance Dual-Task Gait Training in Parkinson's Disease: A Pilot RCT.

PubMed

Schabrun, Siobhan M; Lamont, Robyn M; Brauer, Sandra G

2016-01-01

To investigate the feasibility and safety of a combined anodal transcranial direct current stimulation (tDCS) and dual task gait training intervention in people with Parkinson's Disease (PD) and to provide data to support a sample size calculation for a fully powered trial should trends of effectiveness be present. A pilot, randomized, double-blind, sham-controlled parallel group trial with 12 week follow-up. A university physiotherapy department. Sixteen participants diagnosed with PD received nine dual task gait training sessions over 3 weeks. Participants were randomized to receive either active or sham tDCS applied for the first 20 minutes of each session. The primary outcome was gait speed while undertaking concurrent cognitive tasks (word lists, counting, conversation). Secondary measures included step length, cadence, Timed Up and Go, bradykinesia and motor speed. Gait speed, step length and cadence improved in both groups, under all dual task conditions. This effect was maintained at follow-up. There was no difference between the active and sham tDCS groups. Time taken to perform the TUGwords also improved, with no difference between groups. The active tDCS group did however increase their correct cognitive response rate during the TUGwords and TUGcount. Bradykinesia improved after training in both groups. Three weeks of dual task gait training resulted in improved gait under dual task conditions, and bradykinesia, immediately following training and at 12 weeks follow-up. The only parameter enhanced by tDCS was the number of correct responses while performing the dual task TUG. tDCS applied to M1 may not be an effective adjunct to dual task gait training in PD. Australia-New Zealand Clinical Trials Registry ACTRN12613001093774.

No effect of transcranial direct current stimulation of the dorsolateral prefrontal cortex on short-term memory.

PubMed

Wang, Jing; Wen, Jian-Bing; Li, Xiao-Li

2018-01-01

Short-term memory refers to the capacity for holding information in mind for a short period of time with conscious memorization. It is an important ability for daily life and is impaired in several neurological and psychiatric disorders. Anodal transcranial direct current stimulation (tDCS) applied to the dorsolateral prefrontal cortex (DLPFC) was reported to enhance the capability of short-term memory in healthy subjects. However, results were not consistent and what is the possible impact factor is not known. One important factor that may significantly influence the effect of tDCS is the timing of tDCS administration. In order to explore whether tDCS impact short-term memory and the optimal timing of tDCS administration, we applied anodal tDCS to the left DLPFC to explore the modulatory effect of online and off-line tDCS on digit span as well as visual short-term memory performance in healthy subjects. Results showed tDCS of the left DLPFC did not influence intentional digit span memory performance, whether before the task or during the task. In addition, tDCS of the DLPFC administered before the task showed no effect on visual short-term memory, while there was a trend of increase in false alarm when tDCS of the DLPFC administered during the task. These results did not provide evidence for the enhancement of short-term memory by tDCS of the left DLPFC in healthy subjects, but it suggested an importance of administration time for visual short-term memory. Further studies are required to taking into account the baseline performance of subjects and time-dependence feature of tDCS. © 2017 John Wiley & Sons Ltd.

Probing neural mechanisms underlying auditory stream segregation in humans by transcranial direct current stimulation (tDCS).

PubMed

Deike, Susann; Deliano, Matthias; Brechmann, André

2016-10-01

One hypothesis concerning the neural underpinnings of auditory streaming states that frequency tuning of tonotopically organized neurons in primary auditory fields in combination with physiological forward suppression is necessary for the separation of representations of high-frequency A and low-frequency B tones. The extent of spatial overlap between the tonotopic activations of A and B tones is thought to underlie the perceptual organization of streaming sequences into one coherent or two separate streams. The present study attempts to interfere with these mechanisms by transcranial direct current stimulation (tDCS) and to probe behavioral outcomes reflecting the perception of ABAB streaming sequences. We hypothesized that tDCS by modulating cortical excitability causes a change in the separateness of the representations of A and B tones, which leads to a change in the proportions of one-stream and two-stream percepts. To test this, 22 subjects were presented with ambiguous ABAB sequences of three different frequency separations (∆F) and had to decide on their current percept after receiving sham, anodal, or cathodal tDCS over the left auditory cortex. We could confirm our hypothesis at the most ambiguous ∆F condition of 6 semitones. For anodal compared with sham and cathodal stimulation, we found a significant decrease in the proportion of two-stream perception and an increase in the proportion of one-stream perception. The results demonstrate the feasibility of using tDCS to probe mechanisms underlying auditory streaming through the use of various behavioral measures. Moreover, this approach allows one to probe the functions of auditory regions and their interactions with other processing stages. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Enhanced working memory performance via transcranial direct current stimulation: The possibility of near and far transfer.

PubMed

Trumbo, Michael C; Matzen, Laura E; Coffman, Brian A; Hunter, Michael A; Jones, Aaron P; Robinson, Charles S H; Clark, Vincent P

2016-12-01

Although working memory (WM) training programs consistently result in improvement on the trained task, benefit is typically short-lived and extends only to tasks very similar to the trained task (i.e., near transfer). It is possible that pairing repeated performance of a WM task with brain stimulation encourages plasticity in brain networks involved in WM task performance, thereby improving the training benefit. In the current study, transcranial direct current stimulation (tDCS) was paired with performance of a WM task (n-back). In Experiment 1, participants performed a spatial location-monitoring n-back during stimulation, while Experiment 2 used a verbal identity-monitoring n-back. In each experiment, participants received either active (2.0mA) or sham (0.1mA) stimulation with the anode placed over either the right or the left dorsolateral prefrontal cortex (DLPFC) and the cathode placed extracephalically. In Experiment 1, only participants receiving active stimulation with the anode placed over the right DLPFC showed marginal improvement on the trained spatial n-back, which did not extend to a near transfer (verbal n-back) or far transfer task (a matrix-reasoning task designed to measure fluid intelligence). In Experiment 2, both left and right anode placements led to improvement, and right DLPFC stimulation resulted in numerical (though not sham-adjusted) improvement on the near transfer (spatial n-back) and far transfer (fluid intelligence) task. Results suggest that WM training paired with brain stimulation may result in cognitive enhancement that transfers to performance on other tasks, depending on the combination of training task and tDCS parameters used. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced working memory performance via transcranial direct current stimulation: The possibility of near and far transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trumbo, Michael C.; Matzen, Laura E.; Coffman, Brian A.

Although working memory (WM) training programs consistently result in improvement on the trained task, benefit is typically short-lived and extends only to tasks very similar to the trained task (i.e., near transfer). It is possible that pairing repeated performance of a WM task with brain stimulation encourages plasticity in brain networks involved in WM task performance, thereby improving the training benefit. In the current study, transcranial direct current stimulation (tDCS) was paired with performance of a WM task (n-back). In Experiment 1, participants performed a spatial location-monitoring n-back during stimulation, while Experiment 2 used a verbal identity-monitoring n-back. In eachmore » experiment, participants received either active (2.0 mA) or sham (0.1 mA) stimulation with the anode placed over either the right or the left dorsolateral prefrontal cortex (DLPFC) and the cathode placed extracephalically. In Experiment 1, only participants receiving active stimulation with the anode placed over the right DLPFC showed marginal improvement on the trained spatial n-back, which did not extend to a near transfer (verbal n-back) or far transfer task (a matrix-reasoning task designed to measure fluid intelligence). Here, in Experiment 2, both left and right anode placements led to improvement, and right DLPFC stimulation resulted in numerical (though not sham-adjusted) improvement on the near transfer (spatial n-back) and far transfer (fluid intelligence) task. Results suggest that WM training paired with brain stimulation may result in cognitive enhancement that transfers to performance on other tasks, depending on the combination of training task and tDCS parameters used.« less

Enhanced working memory performance via transcranial direct current stimulation: The possibility of near and far transfer

DOE PAGES

Trumbo, Michael C.; Matzen, Laura E.; Coffman, Brian A.; ...

2016-10-15

Although working memory (WM) training programs consistently result in improvement on the trained task, benefit is typically short-lived and extends only to tasks very similar to the trained task (i.e., near transfer). It is possible that pairing repeated performance of a WM task with brain stimulation encourages plasticity in brain networks involved in WM task performance, thereby improving the training benefit. In the current study, transcranial direct current stimulation (tDCS) was paired with performance of a WM task (n-back). In Experiment 1, participants performed a spatial location-monitoring n-back during stimulation, while Experiment 2 used a verbal identity-monitoring n-back. In eachmore » experiment, participants received either active (2.0 mA) or sham (0.1 mA) stimulation with the anode placed over either the right or the left dorsolateral prefrontal cortex (DLPFC) and the cathode placed extracephalically. In Experiment 1, only participants receiving active stimulation with the anode placed over the right DLPFC showed marginal improvement on the trained spatial n-back, which did not extend to a near transfer (verbal n-back) or far transfer task (a matrix-reasoning task designed to measure fluid intelligence). Here, in Experiment 2, both left and right anode placements led to improvement, and right DLPFC stimulation resulted in numerical (though not sham-adjusted) improvement on the near transfer (spatial n-back) and far transfer (fluid intelligence) task. Results suggest that WM training paired with brain stimulation may result in cognitive enhancement that transfers to performance on other tasks, depending on the combination of training task and tDCS parameters used.« less

Transcranial direct current stimulation facilitates cognitive multi-task performance differentially depending on anode location and subtask

PubMed Central

Scheldrup, Melissa; Greenwood, Pamela M.; McKendrick, Ryan; Strohl, Jon; Bikson, Marom; Alam, Mahtab; McKinley, R. Andy; Parasuraman, Raja

2014-01-01

There is a need to facilitate acquisition of real world cognitive multi-tasks that require long periods of training (e.g., air traffic control, intelligence analysis, medicine). Non-invasive brain stimulation—specifically transcranial Direct Current Stimulation (tDCS)—has promise as a method to speed multi-task training. We hypothesized that during acquisition of the complex multi-task Space Fortress, subtasks that require focused attention on ship control would benefit from tDCS aimed at the dorsal attention network while subtasks that require redirection of attention would benefit from tDCS aimed at the right hemisphere ventral attention network. We compared effects of 30 min prefrontal and parietal stimulation to right and left hemispheres on subtask performance during the first 45 min of training. The strongest effects both overall and for ship flying (control and velocity subtasks) were seen with a right parietal (C4, reference to left shoulder) montage, shown by modeling to induce an electric field that includes nodes in both dorsal and ventral attention networks. This is consistent with the re-orienting hypothesis that the ventral attention network is activated along with the dorsal attention network if a new, task-relevant event occurs while visuospatial attention is focused (Corbetta et al., 2008). No effects were seen with anodes over sites that stimulated only dorsal (C3) or only ventral (F10) attention networks. The speed subtask (update memory for symbols) benefited from an F9 anode over left prefrontal cortex. These results argue for development of tDCS as a training aid in real world settings where multi-tasking is critical. PMID:25249958

Remotely-supervised transcranial direct current stimulation (tDCS) for clinical trials: guidelines for technology and protocols.

PubMed

Charvet, Leigh E; Kasschau, Margaret; Datta, Abhishek; Knotkova, Helena; Stevens, Michael C; Alonzo, Angelo; Loo, Colleen; Krull, Kevin R; Bikson, Marom

2015-01-01

The effect of transcranial direct current stimulation (tDCS) is cumulative. Treatment protocols typically require multiple consecutive sessions spanning weeks or months. However, traveling to clinic for a tDCS session can present an obstacle to subjects and their caregivers. With modified devices and headgear, tDCS treatment can be administered remotely under clinical supervision, potentially enhancing recruitment, throughput, and convenience. Here we propose standards and protocols for clinical trials utilizing remotely-supervised tDCS with the goal of providing safe, reproducible and well-tolerated stimulation therapy outside of the clinic. The recommendations include: (1) training of staff in tDCS treatment and supervision; (2) assessment of the user's capability to participate in tDCS remotely; (3) ongoing training procedures and materials including assessments of the user and/or caregiver; (4) simple and fail-safe electrode preparation techniques and tDCS headgear; (5) strict dose control for each session; (6) ongoing monitoring to quantify compliance (device preparation, electrode saturation/placement, stimulation protocol), with corresponding corrective steps as required; (7) monitoring for treatment-emergent adverse effects; (8) guidelines for discontinuation of a session and/or study participation including emergency failsafe procedures tailored to the treatment population's level of need. These guidelines are intended to provide a minimal level of methodological rigor for clinical trials seeking to apply tDCS outside a specialized treatment center. We outline indication-specific applications (Attention Deficit Hyperactivity Disorder, Depression, Multiple Sclerosis, Palliative Care) following these recommendations that support a standardized framework for evaluating the tolerability and reproducibility of remote-supervised tDCS that, once established, will allow for translation of tDCS clinical trials to a greater size and range of patient populations.

Transcranial direct current stimulation facilitates cognitive multi-task performance differentially depending on anode location and subtask.

PubMed

Scheldrup, Melissa; Greenwood, Pamela M; McKendrick, Ryan; Strohl, Jon; Bikson, Marom; Alam, Mahtab; McKinley, R Andy; Parasuraman, Raja

2014-01-01

There is a need to facilitate acquisition of real world cognitive multi-tasks that require long periods of training (e.g., air traffic control, intelligence analysis, medicine). Non-invasive brain stimulation-specifically transcranial Direct Current Stimulation (tDCS)-has promise as a method to speed multi-task training. We hypothesized that during acquisition of the complex multi-task Space Fortress, subtasks that require focused attention on ship control would benefit from tDCS aimed at the dorsal attention network while subtasks that require redirection of attention would benefit from tDCS aimed at the right hemisphere ventral attention network. We compared effects of 30 min prefrontal and parietal stimulation to right and left hemispheres on subtask performance during the first 45 min of training. The strongest effects both overall and for ship flying (control and velocity subtasks) were seen with a right parietal (C4, reference to left shoulder) montage, shown by modeling to induce an electric field that includes nodes in both dorsal and ventral attention networks. This is consistent with the re-orienting hypothesis that the ventral attention network is activated along with the dorsal attention network if a new, task-relevant event occurs while visuospatial attention is focused (Corbetta et al., 2008). No effects were seen with anodes over sites that stimulated only dorsal (C3) or only ventral (F10) attention networks. The speed subtask (update memory for symbols) benefited from an F9 anode over left prefrontal cortex. These results argue for development of tDCS as a training aid in real world settings where multi-tasking is critical.

Safety and acceptability of transcranial direct current stimulation for the acute treatment of major depressive episodes: Analysis of individual patient data.

PubMed

Moffa, Adriano H; Brunoni, André R; Fregni, Felipe; Palm, Ulrich; Padberg, Frank; Blumberger, Daniel M; Daskalakis, Zafiris J; Bennabi, Djamila; Haffen, Emmanuel; Alonzo, Angelo; Loo, Colleen K

2017-10-15

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation modality that has been increasingly used for major depressive disorder (MDD) treatment. Although studies in healthy volunteers showed that the technique is well-tolerated, tDCS safety and acceptability have not been sufficiently explored in patients with MDD. We collected individual patient data from 6 randomized clinical trials that had been previously identified in a systematic review and meta-analysis. Primary outcomes were safety (rate of adverse events) and acceptability (rate of dropouts). Secondary outcomes were clinical, demographic and treatment predictors of the primary outcomes. Dropout rates between active (8.8%) and sham (12%) groups were not significantly different (OR= 0.7, p=0.38). Adverse event rates between active (73.5%) and sham (68.3%) groups were not significantly different (OR= 1.4, p= 0.23). Higher current densities were associated with lower adverse event rates. Dropout reasons were not systematically reported and adverse events were not collected using questionnaires standardized across studies. Active tDCS is as acceptable and safe as sham tDCS, as found in randomized clinical trials of MDD. Copyright © 2017. Published by Elsevier B.V.

MicroV Technology to Improve Transcranial Color Coded Doppler Examinations.

PubMed

Malferrari, Giovanni; Pulito, Giuseppe; Pizzini, Attilia Maria; Carraro, Nicola; Meneghetti, Giorgio; Sanzaro, Enzo; Prati, Patrizio; Siniscalchi, Antonio; Monaco, Daniela

2018-05-04

The purpose of this review is to provide an update on technology related to Transcranial Color Coded Doppler Examinations. Microvascularization (MicroV) is an emerging Power Doppler technology which can allow visualization of low and weak blood flows even at high depths, thus providing a suitable technique for transcranial ultrasound analysis. With MicroV, reconstruction of the vessel shape can be improved, without any overestimation. Furthermore, by analyzing the Doppler signal, MicroV allows a global image of the Circle of Willis. Transcranial Doppler was originally developed for the velocimetric analysis of intracranial vessels, in particular to detect stenoses and the assessment of collateral circulation. Doppler velocimetric analysis was then compared to other neuroimaging techniques, thus providing a cut-off threshold. Transcranial Color Coded Doppler sonography allowed the characterization of vessel morphology. In both Color Doppler and Power Doppler, the signal overestimated the shape of the intracranial vessels, mostly in the presence of thin vessels and high depths of study. In further neurosonology technology development efforts, attempts have been made to address morphology issues and overcome technical limitations. The use of contrast agents has helped in this regard by introducing harmonics and subtraction software, which allowed better morphological studies of vessels, due to their increased signal-to-noise ratio. Having no limitations in the learning curve, in time and contrast agent techniques, and due to its high signal-to-noise ratio, MicroV has shown great potential to obtain the best morphological definition. Copyright © 2018 by the American Society of Neuroimaging.

Repetitive Transcranial Magnetic Stimulation to Supplementary Motor Area in Refractory Obsessive-Compulsive Disorder Treatment: a Sham-Controlled Trial.

PubMed

Pelissolo, Antoine; Harika-Germaneau, Ghina; Rachid, Fady; Gaudeau-Bosma, Christian; Tanguy, Marie-Laure; BenAdhira, Rene; Bouaziz, Noomane; Popa, Traian; Wassouf, Issa; Saba, Ghassen; Januel, Dominique; Jaafari, Nematollah

2016-08-01

Repetitive transcranial magnetic stimulation has been explored in patients with obsessive-compulsive disorder, but with negative or conflicting results. This randomized double-blind study was designed to assess the efficacy of 1-Hz repetitive transcranial magnetic stimulation over the presupplementary area. Forty medication-resistant patients were assigned to 4 weeks of either active or sham repetitive transcranial magnetic stimulation targeting the presupplementary area with the help of a neuronavigation system. According to the Yale-Brown obsessive-compulsive scale, the baseline-week 4 evolution showed no significant differences between groups. Responder rates at week 4 were not different between groups (repetitive transcranial magnetic stimulation 10.5% vs sham 20%; P=.63). Low-frequency repetitive transcranial magnetic stimulation applied to the presupplementary area seems ineffective for the treatment of obsessive-compulsive disorder patients, at least in severe and drug-refractory cases such as those included in this study. Further research is required to determine profiles of responder patients and appropriate repetitive transcranial magnetic stimulation parameters for obsessive-compulsive disorder. © The Author 2016. Published by Oxford University Press on behalf of CINP.

Transcranial electrical stimulation of the occipital cortex during visual perception modifies the magnitude of BOLD activity: A combined tES-fMRI approach.

PubMed

Alekseichuk, Ivan; Diers, Kersten; Paulus, Walter; Antal, Andrea

2016-10-15

The aim of this study was to investigate if the blood oxygenation level-dependent (BOLD) changes in the visual cortex can be used as biomarkers reflecting the online and offline effects of transcranial electrical stimulation (tES). Anodal transcranial direct current stimulation (tDCS) and 10Hz transcranial alternating current stimulation (tACS) were applied for 10min duration over the occipital cortex of healthy adults during the presentation of different visual stimuli, using a crossover, double-blinded design. Control experiments were also performed, in which sham stimulation as well as another electrode montage were used. Anodal tDCS over the visual cortex induced a small but significant further increase in BOLD response evoked by a visual stimulus; however, no aftereffect was observed. Ten hertz of tACS did not result in an online effect, but in a widespread offline BOLD decrease over the occipital, temporal, and frontal areas. These findings demonstrate that tES during visual perception affects the neuronal metabolism, which can be detected with functional magnetic resonance imaging (fMRI). Copyright © 2016 Elsevier Inc. All rights reserved.

Cranial electrotherapy stimulation and transcranial pulsed current stimulation: a computer based high-resolution modeling study.

PubMed

Datta, Abhishek; Dmochowski, Jacek P; Guleyupoglu, Berkan; Bikson, Marom; Fregni, Felipe

2013-01-15

The field of non-invasive brain stimulation has developed significantly over the last two decades. Though two techniques of noninvasive brain stimulation--transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS)--are becoming established tools for research in neuroscience and for some clinical applications, related techniques that also show some promising clinical results have not been developed at the same pace. One of these related techniques is cranial electrotherapy stimulation (CES), a class of transcranial pulsed current stimulation (tPCS). In order to understand further the mechanisms of CES, we aimed to model CES using a magnetic resonance imaging (MRI)-derived finite element head model including cortical and also subcortical structures. Cortical electric field (current density) peak intensities and distributions were analyzed. We evaluated different electrode configurations of CES including in-ear and over-ear montages. Our results confirm that significant amounts of current pass the skull and reach cortical and subcortical structures. In addition, depending on the montage, induced currents at subcortical areas, such as midbrain, pons, thalamus and hypothalamus are of similar magnitude than that of cortical areas. Incremental variations of electrode position on the head surface also influence which cortical regions are modulated. The high-resolution modeling predictions suggest that details of electrode montage influence current flow through superficial and deep structures. Finally we present laptop based methods for tPCS dose design using dominant frequency and spherical models. These modeling predictions and tools are the first step to advance rational and optimized use of tPCS and CES. Copyright © 2012 Elsevier Inc. All rights reserved.

Transcranial sonography findings related to depression in parkinsonian disorders: cross-sectional study in 126 patients.

PubMed

Bouwmans, Angela E P; Weber, Wim E J; Leentjens, Albert F G; Mess, Werner H

2016-01-01

Background. Transcranial sonography (TCS) has emerged as a potential diagnostic tool for Parkinson's disease. Recent research has suggested that abnormal echogenicity of substantia nigra, raphe nuclei and third ventricle is associated with increased risk of depression among these patients. We sought to reproduce these findings in an ongoing larger study of patients with parkinsonian syndromes. Methods. A total of 126 patients with parkinsonian symptoms underwent the Hamilton Depression Scale, and TCS of the substantia nigra (SN) (n = 126), the raphe nuclei (RN) (n = 80) and the third ventricle (n = 57). We then calculated the correlation between depression and hyper-echogenic SN, hypo-echogenic RN and a wider third ventricle. Results. In patients with PD we found no significant difference of the SN between non-depressed and depressed patients (46% vs. 22%; p = 0.18). Non-depressed patients with other parkinsonisms more often had hyperechogenicity of the SN than depressed patients (51% vs. 0%; p = 0.01). We found no relation between depression and the echogenicity of the RN or the width of the third ventricle. Conclusions. In patients with parkinsonian syndromes, we found no association between depression and hyper-echogenic SN, hypo-echogenic RN or a wider third ventricle, as determined by transcranial sonography.

Transcranial sonography findings related to depression in parkinsonian disorders: cross-sectional study in 126 patients

PubMed Central

Bouwmans, Angela E.P.; Leentjens, Albert F.G.; Mess, Werner H.

2016-01-01

Background. Transcranial sonography (TCS) has emerged as a potential diagnostic tool for Parkinson’s disease. Recent research has suggested that abnormal echogenicity of substantia nigra, raphe nuclei and third ventricle is associated with increased risk of depression among these patients. We sought to reproduce these findings in an ongoing larger study of patients with parkinsonian syndromes. Methods. A total of 126 patients with parkinsonian symptoms underwent the Hamilton Depression Scale, and TCS of the substantia nigra (SN) (n = 126), the raphe nuclei (RN) (n = 80) and the third ventricle (n = 57). We then calculated the correlation between depression and hyper-echogenic SN, hypo-echogenic RN and a wider third ventricle. Results. In patients with PD we found no significant difference of the SN between non-depressed and depressed patients (46% vs. 22%; p = 0.18). Non-depressed patients with other parkinsonisms more often had hyperechogenicity of the SN than depressed patients (51% vs. 0%; p = 0.01). We found no relation between depression and the echogenicity of the RN or the width of the third ventricle. Conclusions. In patients with parkinsonian syndromes, we found no association between depression and hyper-echogenic SN, hypo-echogenic RN or a wider third ventricle, as determined by transcranial sonography. PMID:27231659

Cathodal Transcranial Direct Current Stimulation (tDCS) to the Right Cerebellar Hemisphere Affects Motor Adaptation During Gait.

PubMed

Fernandez, Lara; Albein-Urios, Natalia; Kirkovski, Melissa; McGinley, Jennifer L; Murphy, Anna T; Hyde, Christian; Stokes, Mark A; Rinehart, Nicole J; Enticott, Peter G

2017-02-01

The cerebellum appears to play a key role in the development of internal rules that allow fast, predictive adjustments to novel stimuli. This is crucial for adaptive motor processes, such as those involved in walking, where cerebellar dysfunction has been found to increase variability in gait parameters. Motor adaptation is a process that results in a progressive reduction in errors as movements are adjusted to meet demands, and within the cerebellum, this seems to be localised primarily within the right hemisphere. To examine the role of the right cerebellar hemisphere in adaptive gait, cathodal transcranial direct current stimulation (tDCS) was administered to the right cerebellar hemisphere of 14 healthy adults in a randomised, double-blind, crossover study. Adaptation to a series of distinct spatial and temporal templates was assessed across tDCS condition via a pressure-sensitive gait mat (ProtoKinetics Zeno walkway), on which participants walked with an induced 'limp' at a non-preferred pace. Variability was assessed across key spatial-temporal gait parameters. It was hypothesised that cathodal tDCS to the right cerebellar hemisphere would disrupt adaptation to the templates, reflected in a failure to reduce variability following stimulation. In partial support, adaptation was disrupted following tDCS on one of the four spatial-temporal templates used. However, there was no evidence for general effects on either the spatial or temporal domain. This suggests, under specific conditions, a coupling of spatial and temporal processing in the right cerebellar hemisphere and highlights the potential importance of task complexity in cerebellar function.

Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

PubMed

Kukke, Sahana N; Paine, Rainer W; Chao, Chi-Chao; de Campos, Ana C; Hallett, Mark

2014-06-01

The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies. Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to create recruitment curves. The Boltzmann sigmoidal function was fit to the data, and parameters relating to maximal motor-evoked potential size, curve slope, and stimulus intensity leading to half-maximal motor-evoked potential size were computed from the curve fit. Good to excellent test-retest reliability was found for all corticospinal parameters at rest and during activation with 40 transcranial magnetic stimulation pulses. Through the use of curve fitting, important features of the corticospinal system can be determined with fewer stimuli than typically used for the same information. Determining the recruitment curve provides a basis to understand the state of the corticospinal system and select subject-specific parameters for transcranial magnetic stimulation testing quickly and without unnecessary exposure to magnetic stimulation. This method can be useful in individuals who have difficulty in maintaining stillness, including children and patients with motor disorders.

Cathodal Transcranial Direct Current Stimulation Over Left Dorsolateral Prefrontal Cortex Area Promotes Implicit Motor Learning in a Golf Putting Task.

PubMed

Zhu, Frank F; Yeung, Andrew Y; Poolton, Jamie M; Lee, Tatia M C; Leung, Gilberto K K; Masters, Rich S W

2015-01-01

Implicit motor learning is characterized by low dependence on working memory and stable performance despite stress, fatigue, or multi-tasking. However, current paradigms for implicit motor learning are based on behavioral interventions that are often task-specific and limited when applied in practice. To investigate whether cathodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) area during motor learning suppressed working memory activity and reduced explicit verbal-analytical involvement in movement control, thereby promoting implicit motor learning. Twenty-seven healthy individuals practiced a golf putting task during a Training Phase while receiving either real cathodal tDCS stimulation over the left DLPFC area or sham stimulation. Their performance was assessed during a Test phase on another day. Verbal working memory capacity was assessed before and after the Training Phase, and before the Test Phase. Compared to sham stimulation, real stimulation suppressed verbal working memory activity after the Training Phase, but enhanced golf putting performance during the Training Phase and the Test Phase, especially when participants were required to multi-task. Cathodal tDCS over the left DLPFC may foster implicit motor learning and performance in complex real-life motor tasks that occur during sports, surgery or motor rehabilitation. Copyright © 2015 Elsevier Inc. All rights reserved.

Differential effects of bifrontal and occipital nerve stimulation on pain and fatigue using transcranial direct current stimulation in fibromyalgia patients.

PubMed

To, Wing Ting; James, Evan; Ost, Jan; Hart, John; De Ridder, Dirk; Vanneste, Sven

2017-07-01

Fibromyalgia is a disorder characterized by widespread musculoskeletal pain frequently accompanied by other symptoms such as fatigue. Moderate improvement from pharmacological and non-pharmacological treatments have proposed non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) to the occipital nerve (more specifically the C2 area) or to the dorsolateral prefrontal cortex (DLPFC) as potential treatments. We aimed to explore the effectiveness of repeated sessions of tDCS (eight sessions) targeting the C2 area and DLPFC in reducing fibromyalgia symptoms, more specifically pain and fatigue. Forty-two fibromyalgia patients received either C2 tDCS, DLPFC tDCS or sham procedure (15 C2 tDCS-11 DLPFC tDCS-16 sham). All groups were treated with eight sessions (two times a week for 4 weeks). Our results show that repeated sessions of C2 tDCS significantly improved pain, but not fatigue, in fibromyalgia patients, whereas repeated sessions of DLPFC tDCS significantly improved pain as well as fatigue. This study shows that eight sessions of tDCS targeting the DLPFC have a more general relief in fibromyalgia patients than when targeting the C2 area, suggesting that stimulating different targets with eight sessions of tDCS can lead to benefits on different symptom dimensions of fibromyalgia.

Efficacy of Transcranial Magnetic Stimulation (TMS) in the Treatment of Schizophrenia: A Review of the Literature to Date.

PubMed

Cole, Jonathan C; Green Bernacki, Carolyn; Helmer, Amanda; Pinninti, Narsimha; O'reardon, John P

2015-01-01

We reviewed the literature on transcranial magnetic stimulation and its uses and efficacy in schizophrenia. Multiple sources were examined on transcranial magnetic stimulation efficacy in relieving positive and negative symptoms of schizophrenia. Literature review was conducted via Ovid Medline and PubMed databases. We found multiple published studies and metaanalyses that give evidence that repetitive transcranial magnetic stimulation can have benefit in relieving positive and negative symptoms of schizophrenia, particularly auditory hallucinations. These findings should encourage the psychiatric community to expand research into other applications for which transcranial magnetic stimulation may be used to treat patients with psychiatric disability.

Focused transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex modulates specific domains of self-regulation.

PubMed

Pripfl, Jürgen; Lamm, Claus

2015-02-01

Recent neuroscience theories suggest that different kinds of self-regulation may share a common psychobiological mechanism. However, empirical evidence for a domain general self-regulation mechanism is scarce. The aim of this study was to investigate whether focused anodal transcranial direct current stimulation (tDCS), facilitating the activity of the dorsolateral prefrontal cortex (dlPFC), acts on a domain general self-regulation mechanism and thus modulates both affective and appetitive self-regulation. Twenty smokers participated in this within-subject sham controlled study. Effects of anodal left, anodal right and sham tDCS over the dlPFC on affective picture appraisal and nicotine craving-cue appraisal were assessed. Anodal right tDCS over the dlPFC reduced negative affect in emotion appraisal, but neither modulated regulation of positive emotion appraisal nor of craving appraisal. Anodal left stimulation did not induce any significant effects. The results of our study show that domain specific self-regulation networks are at work in the prefrontal cortex. Focused tDCS modulation of this specific self-regulation network could probably be used during the first phase of nicotine abstinence, during which negative affect might easily result in relapse. These findings have implications for neuroscience models of self-regulation and are of relevance for the development of brain stimulation based treatment methods for neuropsychiatric disorders associated with self-regulation deficits. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Anodal transcranial direct current stimulation transiently improves contrast sensitivity and normalizes visual cortex activation in individuals with amblyopia.

PubMed

Spiegel, Daniel P; Byblow, Winston D; Hess, Robert F; Thompson, Benjamin

2013-10-01

Amblyopia is a neurodevelopmental disorder of vision that is associated with abnormal patterns of neural inhibition within the visual cortex. This disorder is often considered to be untreatable in adulthood because of insufficient visual cortex plasticity. There is increasing evidence that interventions that target inhibitory interactions within the visual cortex, including certain types of noninvasive brain stimulation, can improve visual function in adults with amblyopia. We tested the hypothesis that anodal transcranial direct current stimulation (a-tDCS) would improve visual function in adults with amblyopia by enhancing the neural response to inputs from the amblyopic eye. Thirteen adults with amblyopia participated and contrast sensitivity in the amblyopic and fellow fixing eye was assessed before, during and after a-tDCS or cathodal tDCS (c-tDCS). Five participants also completed a functional magnetic resonance imaging (fMRI) study designed to investigate the effect of a-tDCS on the blood oxygen level-dependent response within the visual cortex to inputs from the amblyopic versus the fellow fixing eye. A subgroup of 8/13 participants showed a transient improvement in amblyopic eye contrast sensitivity for at least 30 minutes after a-tDCS. fMRI measurements indicated that the characteristic cortical response asymmetry in amblyopes, which favors the fellow eye, was reduced by a-tDCS. These preliminary results suggest that a-tDCS deserves further investigation as a potential tool to enhance amblyopia treatment outcomes in adults.

Effects of repetitive transcranial magnetic stimulation in performing eye-hand integration tasks: four preliminary studies with children showing low-functioning autism.

PubMed

Panerai, Simonetta; Tasca, Domenica; Lanuzza, Bartolo; Trubia, Grazia; Ferri, Raffaele; Musso, Sabrina; Alagona, Giovanna; Di Guardo, Giuseppe; Barone, Concetta; Gaglione, Maria P; Elia, Maurizio

2014-08-01

This report, based on four studies with children with low-functioning autism, aimed at evaluating the effects of repetitive transcranial magnetic stimulation delivered on the left and right premotor cortices on eye-hand integration tasks; defining the long-lasting effects of high-frequency repetitive transcranial magnetic stimulation; and investigating the real efficacy of high-frequency repetitive transcranial magnetic stimulation by comparing three kinds of treatments (high-frequency repetitive transcranial magnetic stimulation, a traditional eye-hand integration training, and both treatments combined). Results showed a significant increase in eye-hand performances only when high-frequency repetitive transcranial magnetic stimulation was delivered on the left premotor cortex; a persistent improvement up to 1 h after the end of the stimulation; better outcomes in the treatment combining high-frequency repetitive transcranial magnetic stimulation and eye-hand integration training. Based on these preliminary findings, further evaluations on the usefulness of high-frequency repetitive transcranial magnetic stimulation in rehabilitation of children with autism are strongly recommended. © The Author(s) 2013.

The role of the inferior frontal gyrus in vicarious social touch: A transcranial direct current stimulation (tDCS) study.

PubMed

Peled-Avron, Leehe; Glasner, Laura; Gvirts, Hila Z; Shamay-Tsoory, Simone G

2018-04-30

The neural mechanisms facilitating the experience of vicarious social touch are largely unknown. The right inferior frontal gyrus (rIFG) has been suggested as part of a simulation observation-execution neural network that plays a key role in the perception of tactile stimuli. Considering that vicarious social touch involves vicarious sharing of emotions, we hypothesized that emotional empathy, i.e., the ability to feel what another individual is feeling, modulates the neural responses to vicarious touch. To examine the role of the rIFG in vicarious touch and its modulation by levels of emotional empathy, we used anodal transcranial direct current stimulation (tDCS) on forty participants who observed photos depicting social touch, nonsocial touch or no touch during tDCS or sham stimulation. The results show that while participants with high levels of emotional empathy exhibited no change in ratings of vicarious social touch, participants with low levels of emotional empathy rate human touch as more emotional following anodal stimulation of the rIFG than following sham stimulation. These findings indicate that emotional responses to vicarious social touch are associated with rIFG activity and are modulated by levels of emotional empathy. This result has major therapeutic potential for individuals with low empathic abilities, such as those with ASD. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

The temporary and accumulated effects of transcranial direct current stimulation for the treatment of advanced Parkinson’s disease monkeys

PubMed Central

Li, Hao; Lei, Xiaoguang; Yan, Ting; Li, Hongwei; Huang, Baihui; Li, Ling; Xu, Liqi; Liu, Li; Chen, Nanhui; Lü, Longbao; Ma, Yuanye; Xu, Lin; Li, Jiali; Wang, Zhengbo; Zhang, Baorong; Hu, Xintian

2015-01-01

Transcranial direct current stimulation (tDCS) is a useful noninvasive technique of cortical brain stimulation for the treatment of neurological disorders. Clinical research has demonstrated tDCS with anodal stimulation of primary motor cortex (M1) in Parkinson’s disease (PD) patients significantly improved their motor function. However, few studies have been focused on the optimization of parameters which contributed significantly to the treatment effects of tDCS and exploration of the underline neuronal mechanisms. Here, we used different stimulation parameters of anodal tDCS on M1 for the treatment of aged advanced PD monkeys induced with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) administration, and then analyzed the temporary and accumulated effects of tDCS treatment. The results indicated anodal tDCS on M1 very significantly improved motor ability temporarily; importantly, the treatment effects of anodal tDCS on M1 were quantitatively correlated to the accumulated stimulation instead of the stimuli intensity or duration respectively. In addition, c-fos staining showed tDCS treatment effects activated the neurons both in M1 and substantia nigra (SN). Therefore, we propose that long time and continue anodal tDCS on M1 is a better strategy to improve the motor symptoms of PD than individual manipulation of stimuli intensity or duration. PMID:26220760

Low-frequency transcranial magnetic stimulation is beneficial for enhancing synaptic plasticity in the aging brain.

PubMed

Zhang, Zhan-Chi; Luan, Feng; Xie, Chun-Yan; Geng, Dan-Dan; Wang, Yan-Yong; Ma, Jun

2015-06-01

In the aging brain, cognitive function gradually declines and causes a progressive reduction in the structural and functional plasticity of the hippocampus. Transcranial magnetic stimulation is an emerging and novel neurological and psychiatric tool used to investigate the neurobiology of cognitive function. Recent studies have demonstrated that low-frequency transcranial magnetic stimulation (≤1 Hz) ameliorates synaptic plasticity and spatial cognitive deficits in learning-impaired mice. However, the mechanisms by which this treatment improves these deficits during normal aging are still unknown. Therefore, the current study investigated the effects of transcranial magnetic stimulation on the brain-derived neurotrophic factor signal pathway, synaptic protein markers, and spatial memory behavior in the hippocampus of normal aged mice. The study also investigated the downstream regulator, Fyn kinase, and the downstream effectors, synaptophysin and growth-associated protein 43 (both synaptic markers), to determine the possible mechanisms by which transcranial magnetic stimulation regulates cognitive capacity. Transcranial magnetic stimulation with low intensity (110% average resting motor threshold intensity, 1 Hz) increased mRNA and protein levels of brain-derived neurotrophic factor, tropomyosin receptor kinase B, and Fyn in the hippocampus of aged mice. The treatment also upregulated the mRNA and protein expression of synaptophysin and growth-associated protein 43 in the hippocampus of these mice. In conclusion, brain-derived neurotrophic factor signaling may play an important role in sustaining and regulating structural synaptic plasticity induced by transcranial magnetic stimulation in the hippocampus of aging mice, and Fyn may be critical during this regulation. These responses may change the structural plasticity of the aging hippocampus, thereby improving cognitive function.

The Significance of Brain Transcranial Sonography in Burning Mouth Syndrome: a Pilot Study.

PubMed

Zavoreo, Iris; Vučićević, Vanja; Boras; Zadravec, Dijana; Bašić, Vanja; Kes; Ciliga, Dubravka; Gabrić, Dragana

2017-03-01

Burning mouth syndrome (BMS) is a chronic disorder which is affecting mostly postmenopausal women and is characterized by burning symptoms in the oral cavity on the clinically healthy oral mucosa. Also, the results of previous studies suggested a possible role of peripheral and/or central neurological disturbances in these patients. The aim of this study was to analyze patients with burning mouth syndrome using transcranial sonography. By use of transcranial sonography of the brain parenchyma, substantia nigra , midbrain raphe and brain nucleus were evaluated in 20 patients with BMS (64.7±12.3 years) and 20 controls with chronic pain in the lumbosacral region (61.5±15). Statistical analysis was performed by use of Student t test with significance set at p<0.05. The results of this study have shown hypoechogenicity of the substantia nigra and midbrain raphe as well as hyperechogenicity of the brain nucleus in BMS patients (p<0,05) as compared to controls. Altered transcranial sonography findings of the brain parenchyma , midbrain raphe and brain nucl eus in patients with burning mouth syndrome might reflect central disturbances within this syndrome. Burning Mouth Syndrome; Transcranial Sonography; substantia nigra; Midbrain Raphe Nuclei; Red Nucleus.

Against Strong Ethical Parity: Situated Cognition Theses and Transcranial Brain Stimulation

PubMed Central

Heinrichs, Jan-Hendrik

2017-01-01

According to a prominent suggestion in the ethics of transcranial neurostimulation the effects of such devices can be treated as ethically on par with established, pre-neurotechnological alterations of the mind. This parity allegedly is supported by situated cognition theories showing how external devices can be part of a cognitive system. This article will evaluate this suggestion. It will reject the claim, that situated cognition theories support ethical parity. It will however point out another reason, why external carriers or modifications of the mental might come to be considered ethically on par with internal carriers. Section “Why Could There Be Ethical Parity between Neural Tissue and External Tools?” presents the ethical parity theses between external and internal carriers of the mind as well as neurotechnological alterations and established alterations. Section “Extended, Embodied, Embedded: Situated Cognition as a Relational Thesis” will elaborate the different situated cognition approaches and their relevance for ethics. It will evaluate, whether transcranial stimulation technologies are plausible candidates for situated cognition theses. Section “On the Ethical Relevance of Situated Cognition Theses” will discuss criteria for evaluating whether a cognitive tool is deeply embedded with a cognitive system and apply these criteria to transcranial brain stimulation technologies. Finally it will discuss the role diverse versions of situated cognition theory can play in the ethics of altering mental states, especially the ethics of transcranial brain stimulation technologies. PMID:28443008

Effect of Transcranial Magnetic Stimulation on Neuronal Networks

NASA Astrophysics Data System (ADS)

Unsal, Ahmet; Hadimani, Ravi; Jiles, David

2013-03-01

The human brain contains around 100 billion nerve cells controlling our day to day activities. Consequently, brain disorders often result in impairments such as paralysis, loss of coordination and seizure. It has been said that 1 in 5 Americans suffer some diagnosable mental disorder. There is an urgent need to understand the disorders, prevent them and if possible, develop permanent cure for them. As a result, a significant amount of research activities is being directed towards brain research. Transcranial Magnetic Stimulation (TMS) is a promising tool for diagnosing and treating brain disorders. It is a non-invasive treatment method that produces a current flow in the brain which excites the neurons. Even though TMS has been verified to have advantageous effects on various brain related disorders, there have not been enough studies on the impact of TMS on cells. In this study, we are investigating the electrophysiological effects of TMS on one dimensional neuronal culture grown in a circular pathway. Electrical currents are produced on the neuronal networks depending on the directionality of the applied field. This aids in understanding how neuronal networks react under TMS treatment.

Transient basilar artery occlusion monitored by transcranial color Doppler presenting with a spectacular shrinking deficit: a case report

PubMed Central

2010-01-01

Introduction We describe the case of a 79-year-old Caucasian Italian woman with a transient basilar occlusion monitored by transcranial Doppler, with subsequent recanalization and clinical shrinking deficit. This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. This case is important and needs to be reported because transient basilar occlusion may be easily diagnosed if transcranial Doppler is performed. Case presentation A 79-year-old woman affected by chronic atrial fibrillation and not treated with oral anticoagulants, cardioverted to sinus rhythm during a gastric endoscopy. She then showed a sudden-onset loss of consciousness, horizontal and vertical gaze palsy, tetraparesis and bilateral miosis and coma. Two hours later, the symptoms resolved quickly, leaving no residual neurologic deficits. Transcranial Doppler examination showed a dampened flow in the basilar artery in the emergency examination and a restored flow when the symptoms resolved. Conclusion This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. We believe that transcranial Doppler should be performed in all cases of unexplained acute loss of consciousness, in particular, if associated with signs of brainstem dysfunctions. PMID:20205759

Noninvasive transcranial focused ultrasonic-magnetic stimulation for modulating brain oscillatory activity

NASA Astrophysics Data System (ADS)

Yuan, Yi; Chen, Yudong; Li, Xiaoli

2016-02-01

A novel technique, transcranial focused ultrasonic-magnetic stimulation (tFUMS), has been developed for noninvasive brain modulation in vivo. tFUMS has a higher spatial resolution (<2 mm) and a higher penetration depth than other noninvasive neuromodulation methods. The in vivo animal experimental results show that tFUMS can not only increase the power of local field potentials and the firing rate of the neurons, but also enhance the effect of transcranial focused ultrasound stimulation on the neuromodulation. The results demonstrate that tFUMS can modulate brain oscillatory activities by stimulating brain tissues.

Effects of a common transcranial direct current stimulation (tDCS) protocol on motor evoked potentials found to be highly variable within individuals over 9 testing sessions.

PubMed

Horvath, Jared Cooney; Vogrin, Simon J; Carter, Olivia; Cook, Mark J; Forte, Jason D

2016-09-01

Transcranial direct current stimulation (tDCS) uses a weak electric current to modulate neuronal activity. A neurophysiologic outcome measure to demonstrate reliable tDCS modulation at the group level is transcranial magnetic stimulation engendered motor evoked potentials (MEPs). Here, we conduct a study testing the reliability of individual MEP response patterns following a common tDCS protocol. Fourteen participants (7m/7f) each underwent nine randomized sessions of 1 mA, 10 min tDCS (3 anode; 3 cathode; 3 sham) delivered using an M1/orbito-frontal electrode montage (sessions separated by an average of ~5.5 days). Fifteen MEPs were obtained prior to, immediately following and in 5 min intervals for 30 min following tDCS. TMS was delivered at 130 % resting motor threshold using neuronavigation to ensure consistent coil localization. A number of non-experimental variables were collected during each session. At the individual level, considerable variability was seen among different testing sessions. No participant demonstrated an excitatory response ≥20 % to all three anodal sessions, and no participant demonstrated an inhibitory response ≥20 % to all three cathodal sessions. Intra-class correlation revealed poor anodal and cathodal test-retest reliability [anode: ICC(2,1) = 0.062; cathode: ICC(2,1) = 0.055] and moderate sham test-retest reliability [ICC(2,1) = 0.433]. Results also revealed no significant effect of tDCS at the group level. Using this common protocol, we found the effects of tDCS on MEP amplitudes to be highly variable at the individual level. In addition, no significant effects of tDCS on MEP amplitude were found at the group level. Future studies should consider utilizing a more strict experimental protocol to potentially account for intra-individual response variations.

Differential behavioral and physiological effects of anodal transcranial direct current stimulation in healthy adults of younger and older age

PubMed Central

Heise, Kirstin-Friederike; Niehoff, Martina; Feldheim, J.-F.; Liuzzi, Gianpiero; Gerloff, Christian; Hummel, Friedhelm C.

2014-01-01

Changes in γ-aminobutyric acid (GABA) mediated synaptic transmission have been associated with age-related motor and cognitive functional decline. Since anodal transcranial direct current stimulation (atDCS) has been suggested to target cortical GABAergic inhibitory interneurons, its potential for the treatment of deficient inhibitory activity and functional decline is being increasingly discussed. Therefore, after-effects of a single session of atDCS on resting-state and event-related short-interval intracortical inhibition (SICI) as evaluated with double-pulse TMS and dexterous manual performance were examined using a sham-controlled cross-over design in a sample of older and younger participants. The atDCS effect on resting-state inhibition differed in direction, magnitude, and timing, i.e., late relative release of inhibition in the younger and early relative increase in inhibition in the older. More pronounced release of event-related inhibition after atDCS was exclusively seen in the older. Event-related modulation of inhibition prior to stimulation predicted the magnitude of atDCS-induced effects on resting-state inhibition. Specifically, older participants with high modulatory capacity showed a disinhibitory effect comparable to the younger. Beneficial effects on behavior were mainly seen in the older and in tasks requiring higher dexterity, no clear association with physiological changes was found. Differential effects of atDCS on SICI, discussed to reflect GABAergic inhibition at the level of the primary motor cortex, might be distinct in older and younger participants depending on the functional integrity of the underlying neural network. Older participants with preserved modulatory capacity, i.e., a physiologically “young” motor network, were more likely to show a disinhibitory effect of atDCS. These results favor individually tailored application of tDCS with respect to specific target groups. PMID:25071555

Introducing graph theory to track for neuroplastic alterations in the resting human brain: a transcranial direct current stimulation study.

PubMed

Polanía, Rafael; Paulus, Walter; Antal, Andrea; Nitsche, Michael A

2011-02-01

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that alters cortical excitability and activity in a polarity-dependent way. Stimulation for a few minutes has been shown to induce plastic alterations of cortical excitability and to improve cognitive performance. These effects might be related to stimulation-induced alterations of functional cortical network connectivity. We aimed to investigate the impact of tDCS on cortical network function by functional connectivity and graph theoretical analysis of the BOLD fMRI spontaneous activity. fMRI resting-state datasets were acquired immediately before and after 10-min bipolar tDCS during rest, with the anode placed over the left primary motor cortex (M1) and the cathode over the contralateral frontopolar cortex. For each dataset, grey matter voxel-based synchronization matrices were calculated and thresholded to construct undirected graphs. Nodal connectivity degree and minimum path length maps were calculated and compared before and after tDCS. Nodal minimum path lengths significantly increased in the left somatomotor (SM1) cortex after anodal tDCS, which means that the number of direct functional connections from the left SM1 to topologically distant grey matter voxels significantly decreased. In contrast, functional coupling between premotor and superior parietal areas with the left SM1 significantly increased. Additionally, the nodal connectivity degree in the left posterior cingulate cortex (PCC) area as well as in the right dorsolateral prefrontal cortex (right DLPFC) significantly increased. In summary, we provide initial support that tDCS-induced neuroplastic alterations might be related to functional connectivity changes in the human brain. Additionally, we propose our approach as a powerful method to track for neuroplastic changes in the human brain. Copyright © 2010 Elsevier Inc. All rights reserved.

No effects of transcranial DLPFC stimulation on implicit task sequence learning and consolidation.

PubMed

Savic, Branislav; Cazzoli, Dario; Müri, René; Meier, Beat

2017-08-29

Neurostimulation of the dorsolateral prefrontal cortex (DLPFC) can modulate performance in cognitive tasks. In a recent study, however, transcranial direct current stimulation (tDCS) of the DLPFC did not affect implicit task sequence learning and consolidation in a paradigm that involved bimanual responses. Because bimanual performance increases the coupling between homologous cortical areas of the hemispheres and left and right DLPFC were stimulated separately the null findings may have been due to the bimanual setup. The aim of the present study was to test the effect of neuro-stimulation on sequence learning in a uni-manual setup. For this purpose two experiments were conducted. In Experiment 1, the DLPFC was stimulated with tDCS. In Experiment 2 the DLPFC was stimulated with transcranial magnetic stimulation (TMS). In both experiments, consolidation was measured 24 hours later. The results showed that sequence learning was present in all conditions and sessions, but it was not influenced by stimulation. Likewise, consolidation of sequence learning was robust across sessions, but it was not influenced by stimulation. These results replicate and extend previous findings. They indicate that established tDCS and TMS protocols on the DLPFC do not influence implicit task sequence learning and consolidation.

Detection and volume estimation of embolic air in the middle cerebral artery using transcranial Doppler sonography.

PubMed

Bunegin, L; Wahl, D; Albin, M S

1994-03-01

Cerebral embolism has been implicated in the development of cognitive and neurological deficits following bypass surgery. This study proposes methodology for estimating cerebral air embolus volume using transcranial Doppler sonography. Transcranial Doppler audio signals of air bubbles in the middle cerebral artery obtained from in vivo experiments were subjected to a fast-Fourier transform analysis. Audio segments when no air was present as well as artifact resulting from electrocautery and sensor movement were also subjected to fast-Fourier transform analysis. Spectra were compared, and frequency and power differences were noted and used for development of audio band-pass filters for isolation of frequencies associated with air emboli. In a bench model of the middle cerebral artery circulation, repetitive injections of various air volumes between 0.5 and 500 microL were made. Transcranial Doppler audio output was band-pass filtered, acquired digitally, then subjected to a fast-Fourier transform power spectrum analysis and power spectrum integration. A linear least-squares correlation was performed on the data. Fast-Fourier transform analysis of audio segments indicated that frequencies between 250 and 500 Hz are consistently dominant in the spectrum when air emboli are present. Background frequencies appear to be below 240 Hz, and artifact resulting from sensor movement and electrocautery appears to be below 300 Hz. Data from the middle cerebral artery model filtered through a 307- to 450-Hz band-pass filter yielded a linear relation between emboli volume and the integrated value of the power spectrum near 40 microL. Detection of emboli less than 0.5 microL was inconsistent, and embolus volumes greater than 40 microL were indistinguishable from one another. The preliminary technique described in this study may represent a starting point from which automated detection and volume estimation of cerebral emboli might be approached.

Effect of microscopic modeling of skin in electrical and thermal analysis of transcranial direct current stimulation

NASA Astrophysics Data System (ADS)

Gomez-Tames, Jose; Sugiyama, Yukiya; Laakso, Ilkka; Tanaka, Satoshi; Koyama, Soichiro; Sadato, Norihiro; Hirata, Akimasa

2016-12-01

Transcranial direct current stimulation (tDCS) is a neuromodulation scheme where a small current is delivered to the brain via two electrodes attached to the scalp. The electrode design is an important topic, not only as regards efficacy, but also from a safety perspective, as tDCS may be related to skin lesions that are sometimes observed after stimulation. Previous computational models of tDCS have omitted the effects of microscopic structures in the skin, and the different soak conditions of the electrodes, and model validation has been limited. In this study, multiphysics and multiscale analysis are proposed to demonstrate the importance of microscopic modeling of the skin, in order to clarify the effects of the internal electric field, and to examine temperature elevation around the electrodes. This novel microscopic model of the skin layer took into consideration the effect of saline/water penetration in hair follicles and sweat ducts on the field distribution around the electrodes. The temperature elevation in the skin was then computed by solving the bioheat equation. Also, a multiscale model was introduced to account for macroscopic and microscopic tissues of the head and skin, which was validated by measurement of the head resistance during tDCS. As a result, the electric field in the microscopic model of the skin was less localized when the follicles/ducts were filled with saline instead of hair or tap water. Temperature elevation was also lessened with saline, in comparison with other substances. Saline, which may penetrate the hair follicles and sweat ducts, suppressed the field concentration around the electrodes. For conventional magnitudes of current injection, and a head resistance of less than 10 kΩ, the temperature elevation in the skin when using saline-soaked electrodes was low, less than 0.1 °C, and unlikely to cause adverse thermal effects.

NIRS-EEG joint imaging during transcranial direct current stimulation: Online parameter estimation with an autoregressive model.

PubMed

Sood, Mehak; Besson, Pierre; Muthalib, Makii; Jindal, Utkarsh; Perrey, Stephane; Dutta, Anirban; Hayashibe, Mitsuhiro

2016-12-01

Transcranial direct current stimulation (tDCS) has been shown to perturb both cortical neural activity and hemodynamics during (online) and after the stimulation, however mechanisms of these tDCS-induced online and after-effects are not known. Here, online resting-state spontaneous brain activation may be relevant to monitor tDCS neuromodulatory effects that can be measured using electroencephalography (EEG) in conjunction with near-infrared spectroscopy (NIRS). We present a Kalman Filter based online parameter estimation of an autoregressive (ARX) model to track the transient coupling relation between the changes in EEG power spectrum and NIRS signals during anodal tDCS (2mA, 10min) using a 4×1 ring high-definition montage. Our online ARX parameter estimation technique using the cross-correlation between log (base-10) transformed EEG band-power (0.5-11.25Hz) and NIRS oxy-hemoglobin signal in the low frequency (≤0.1Hz) range was shown in 5 healthy subjects to be sensitive to detect transient EEG-NIRS coupling changes in resting-state spontaneous brain activation during anodal tDCS. Conventional sliding window cross-correlation calculations suffer a fundamental problem in computing the phase relationship as the signal in the window is considered time-invariant and the choice of the window length and step size are subjective. Here, Kalman Filter based method allowed online ARX parameter estimation using time-varying signals that could capture transients in the coupling relationship between EEG and NIRS signals. Our new online ARX model based tracking method allows continuous assessment of the transient coupling between the electrophysiological (EEG) and the hemodynamic (NIRS) signals representing resting-state spontaneous brain activation during anodal tDCS. Published by Elsevier B.V.

Individualized model predicts brain current flow during transcranial direct-current stimulation treatment in responsive stroke patient.

PubMed

Datta, Abhishek; Baker, Julie M; Bikson, Marom; Fridriksson, Julius

2011-07-01

Although numerous published reports have demonstrated the beneficial effects of transcranial direct-current stimulation (tDCS) on task performance, fundamental questions remain regarding the optimal electrode configuration on the scalp. Moreover, it is expected that lesioned brain tissue will influence current flow and should therefore be considered (and perhaps leveraged) in the design of individualized tDCS therapies for stroke. The current report demonstrates how different electrode configurations influence the flow of electrical current through brain tissue in a patient who responded positively to a tDCS treatment targeting aphasia. The patient, a 60-year-old man, sustained a left hemisphere ischemic stroke (lesion size = 87.42 mL) 64 months before his participation. In this study, we present results from the first high-resolution (1 mm(3)) model of tDCS in a brain with considerable stroke-related damage; the model was individualized for the patient who received anodal tDCS to his left frontal cortex with the reference cathode electrode placed on his right shoulder. We modeled the resulting brain current flow and also considered three additional reference electrode positions: right mastoid, right orbitofrontal cortex, and a "mirror" configuration with the anode over the undamaged right cortex. Our results demonstrate the profound effect of lesioned tissue on resulting current flow and the ability to modulate current pattern through the brain, including perilesional regions, through electrode montage design. The complexity of brain current flow modulation by detailed normal and pathologic anatomy suggest: (1) That computational models are critical for the rational interpretation and design of individualized tDCS stroke-therapy; and (2) These models must accurately reproduce head anatomy as shown here. Copyright © 2011 Elsevier Inc. All rights reserved.

Effect of anatomical variability in brain on transcranial magnetic stimulation treatment

NASA Astrophysics Data System (ADS)

Syeda, F.; Magsood, H.; Lee, E. G.; El-Gendy, A. A.; Jiles, D. C.; Hadimani, R. L.

2017-05-01

Transcranial Magnetic Stimulation is a non-invasive clinical therapy used to treat depression and migraine, and shows further promise as treatment for Parkinson's disease, Alzheimer's disease, and other neurological disorders. However, it is yet unclear as to how anatomical differences may affect stimulation from this treatment. We use finite element analysis to model and analyze the results of Transcranial Magnetic Stimulation in various head models. A number of heterogeneous head models have been developed using MRI data of real patients, including healthy individuals as well as patients of Parkinson's disease. Simulations of Transcranial Magnetic Stimulation performed on 22 anatomically different models highlight the differences in induced stimulation. A standard Figure of 8 coil is used with frequency 2.5 kHz, placed 5 mm above the head. We compare cortical stimulation, volume of brain tissue stimulated, specificity, and maximum E-field induced in the brain for models ranging from ages 20 to 60. Results show that stimulation varies drastically between patients of the same age and health status depending upon brain-scalp distance, which is not necessarily a linear progression with age.

A novel decision tree approach based on transcranial Doppler sonography to screen for blunt cervical vascular injuries.

PubMed

Purvis, Dianna; Aldaghlas, Tayseer; Trickey, Amber W; Rizzo, Anne; Sikdar, Siddhartha

2013-06-01

Early detection and treatment of blunt cervical vascular injuries prevent adverse neurologic sequelae. Current screening criteria can miss up to 22% of these injuries. The study objective was to investigate bedside transcranial Doppler sonography for detecting blunt cervical vascular injuries in trauma patients using a novel decision tree approach. This prospective pilot study was conducted at a level I trauma center. Patients undergoing computed tomographic angiography for suspected blunt cervical vascular injuries were studied with transcranial Doppler sonography. Extracranial and intracranial vasculatures were examined with a portable power M-mode transcranial Doppler unit. The middle cerebral artery mean flow velocity, pulsatility index, and their asymmetries were used to quantify flow patterns and develop an injury decision tree screening protocol. Student t tests validated associations between injuries and transcranial Doppler predictive measures. We evaluated 27 trauma patients with 13 injuries. Single vertebral artery injuries were most common (38.5%), followed by single internal carotid artery injuries (30%). Compared to patients without injuries, mean flow velocity asymmetry was higher for single internal carotid artery (P = .003) and single vertebral artery (P = .004) injuries. Similarly, pulsatility index asymmetry was higher in single internal carotid artery (P = .015) and single vertebral artery (P = .042) injuries, whereas the lowest pulsatility index was elevated for bilateral vertebral artery injuries (P = .006). The decision tree yielded 92% specificity, 93% sensitivity, and 93% correct classifications. In this pilot feasibility study, transcranial Doppler measures were significantly associated with the blunt cervical vascular injury status, suggesting that transcranial Doppler sonography might be a viable bedside screening tool for trauma. Patient-specific hemodynamic information from transcranial Doppler assessment has the potential to alter

The Significance of Brain Transcranial Sonography in Burning Mouth Syndrome: a Pilot Study

PubMed Central

Zavoreo, Iris; Vučićević, Vanja; Zadravec, Dijana; Bašić, Vanja; Kes; Ciliga, Dubravka; Gabrić, Dragana

2017-01-01

Objective Burning mouth syndrome (BMS) is a chronic disorder which is affecting mostly postmenopausal women and is characterized by burning symptoms in the oral cavity on the clinically healthy oral mucosa. Also, the results of previous studies suggested a possible role of peripheral and/or central neurological disturbances in these patients. The aim of this study was to analyze patients with burning mouth syndrome using transcranial sonography. Methods By use of transcranial sonography of the brain parenchyma, substantia nigra, midbrain raphe and brain nucleus were evaluated in 20 patients with BMS (64.7±12.3 years) and 20 controls with chronic pain in the lumbosacral region (61.5±15). Statistical analysis was performed by use of Student t test with significance set at p<0.05. Results The results of this study have shown hypoechogenicity of the substantia nigra and midbrain raphe as well as hyperechogenicity of the brain nucleus in BMS patients (p<0,05) as compared to controls. Conclusions Altered transcranial sonography findings of the brain parenchyma, midbrain raphe and brain nucleus in patients with burning mouth syndrome might reflect central disturbances within this syndrome. Key words Burning Mouth Syndrome; Transcranial Sonography; substantia nigra; Midbrain Raphe Nuclei; Red Nucleus PMID:28740270

Transcranial direct current stimulation in post-stroke sub-acute aphasia: study protocol for a randomized controlled trial.

PubMed

Spielmann, Kerstin; van de Sandt-Koenderman, W Mieke E; Heijenbrok-Kal, Majanka H; Ribbers, Gerard M

2016-08-02

Transcranial direct current stimulation (tDCS) is a promising new technique to optimize the effect of regular Speech and Language Therapy (SLT) in the context of aphasia rehabilitation. The present study focuses on the effect of tDCS provided during SLT in the sub-acute stage after stroke. The primary aim is to evaluate the potential effect of tDCS on language functioning, specifically on word-finding, as well as generalization effects to verbal communication. The secondary aim is to evaluate its effect on social participation and quality of life, and its cost-effectiveness. We strive to include 58 stroke patients with aphasia, enrolled in an inpatient or outpatient stroke rehabilitation program, in a multicenter, double-blind, randomized controlled trial with two parallel groups and 6 months' follow-up. Patients will participate in two separate intervention weeks, with a pause of 2 weeks in between, in the context of their regular aphasia rehabilitation program. The two intervention weeks comprise daily 45-minute sessions of word-finding therapy, combined with either anodal tDCS over the left inferior frontal gyrus (1 mA, 20 minutes; experimental condition) or sham-tDCS over the same region (control condition). The primary outcome measure is word-finding. Secondary outcome measures are verbal communication, social participation, quality of life, and cost-effectiveness of the intervention. Our results will contribute to the discussion on whether tDCS should be implemented in regular aphasia rehabilitation programs for the sub-acute post-stroke population in terms of (cost-)effectiveness. Nederlands Trail Register: NTR4364 . Registered on 21 February 2014.

Transcranial direct current stimulation improves short-term memory in an animal model of attention-deficit/hyperactivity disorder.

PubMed

Leffa, Douglas Teixeira; de Souza, Andressa; Scarabelot, Vanessa Leal; Medeiros, Liciane Fernandes; de Oliveira, Carla; Grevet, Eugenio Horacio; Caumo, Wolnei; de Souza, Diogo Onofre; Rohde, Luis Augusto Paim; Torres, Iraci L S

2016-02-01

Attention deficit hyperactivity disorder (ADHD) is characterized by impairing levels of hyperactivity, impulsivity and inattention. However, different meta-analyses have reported disruptions in short and long-term memory in ADHD patients. Previous studies indicate that mnemonic dysfunctions might be the result of deficits in attentional circuits, probably due to ineffective dopaminergic modulation of hippocampal synaptic plasticity. In this study we aimed to evaluate the potential therapeutic effects of a neuromodulatory technique, transcranial direct current stimulation (tDCS), in short-term memory (STM) deficits presented by the spontaneous hypertensive rats (SHR), the most widely used animal model of ADHD. Adult male SHR and Wistar Kyoto rats (WKY) were subjected to a constant electrical current of 0.5 mA intensity applied on the frontal cortex for 20 min/day during 8 days. STM was evaluated with an object recognition test conducted in an open field. Exploration time and locomotion were recorded, and brain regions were dissected to determine dopamine and BDNF levels. SHR spent less time exploring the new object when compared to WKY, and tDCS improved object recognition deficits in SHR without affecting WKY performance. Locomotor activity was higher in SHR and it was not affected by tDCS. After stimulation, dopamine levels were increased in the hippocampus and striatum of both strains, while BDNF levels were increased only in the striatum of WKY. These findings suggest that tDCS on the frontal cortex might be able to improve STM deficits present in SHR, which is potentially related to dopaminergic neurotransmission in the hippocampus and striatum of those animals. Copyright © 2016. Published by Elsevier B.V.