A microprocessor-based multichannel subsensory stochastic resonance electrical stimulator.

PubMed

Chang, Gwo-Ching

2013-01-01

Stochastic resonance electrical stimulation is a novel intervention which provides potential benefits for improving postural control ability in the elderly, those with diabetic neuropathy, and stroke patients. In this paper, a microprocessor-based subsensory white noise electrical stimulator for the applications of stochastic resonance stimulation is developed. The proposed stimulator provides four independent programmable stimulation channels with constant-current output, possesses linear voltage-to-current relationship, and has two types of stimulation modes, pulse amplitude and width modulation.

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 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.

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.

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…

Improving ideomotor limb apraxia by electrical stimulation of the left posterior parietal cortex.

PubMed

Bolognini, Nadia; Convento, Silvia; Banco, Elisabetta; Mattioli, Flavia; Tesio, Luigi; Vallar, Giuseppe

2015-02-01

Limb apraxia, a deficit of planning voluntary gestures, is most frequently caused by damage to the left hemisphere, where, according to an influential neurofunctional model, gestures are planned, before being executed through the motor cortex of the hemisphere contralateral to the acting hand. We used anodal transcranial direct current stimulation delivered to the left posterior parietal cortex (PPC), the right motor cortex (M1), and a sham stimulation condition, to modulate the ability of six left-brain-damaged patients with ideomotor apraxia, and six healthy control subjects, to imitate hand gestures, and to perform skilled hand movements using the left hand. Transcranial direct current stimulation delivered to the left PPC reduced the time required to perform skilled movements, and planning, but not execution, times in imitating gestures, in both patients and controls. In patients, the amount of decrease of planning times brought about by left PPC transcranial direct current stimulation was influenced by the size of the parietal lobe damage, with a larger parietal damage being associated with a smaller improvement. Of interest from a clinical perspective, left PPC stimulation also ameliorated accuracy in imitating hand gestures in patients. Instead, transcranial direct current stimulation to the right M1 diminished execution, but not planning, times in both patients and healthy controls. In conclusion, by using a transcranial stimulation approach, we temporarily improved ideomotor apraxia in the left hand of left-brain-damaged patients, showing a role of the left PPC in planning gestures. This evidence opens up novel perspectives for the use of transcranial direct current stimulation in the rehabilitation of limb apraxia. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Transcranial Direct Current Stimulation Improves Audioverbal Memory in Stroke Patients

PubMed Central

Kazuta, Toshinari; Takeda, Kotaro; Osu, Rieko; Tanaka, Satoshi; Oishi, Ayako; Kondo, Kunitsugu; Liu, Meigen

2017-01-01

Objective The aim of this study was to investigate whether anodal transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance in stroke patients. Design Twelve stroke patients with audioverbal memory impairment participated in a single-masked, crossover, and sham-controlled experiment. The anodal or sham transcranial direct current stimulation was applied during the Rey Auditory Verbal Learning Test, which evaluates the ability to recall a list of 15 heard words over five trials. The number of correctly recalled words was compared between the anodal and sham conditions and the influence of transcranial direct current stimulation on serial position effect of the 15 words was also examined. Results The increase in the number of correctly recalled words from the first to the fifth trial was significantly greater in the anodal condition than in the sham condition (P < 0.01). There was a significant difference (P < 0.01) between the anodal and sham conditions in the number of correctly recalled words within the first five words (primacy region) over the second to fifth trial trials, but not in the middle (next five words) or recency (last five words) regions. Conclusions Anodal transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance and induced the primacy effect in stroke patients. PMID:28085735

Transcranial Direct Current Stimulation Improves Audioverbal Memory in Stroke Patients.

PubMed

Kazuta, Toshinari; Takeda, Kotaro; Osu, Rieko; Tanaka, Satoshi; Oishi, Ayako; Kondo, Kunitsugu; Liu, Meigen

2017-08-01

The aim of this study was to investigate whether anodal transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance in stroke patients. Twelve stroke patients with audioverbal memory impairment participated in a single-masked, crossover, and sham-controlled experiment. The anodal or sham transcranial direct current stimulation was applied during the Rey Auditory Verbal Learning Test, which evaluates the ability to recall a list of 15 heard words over five trials. The number of correctly recalled words was compared between the anodal and sham conditions and the influence of transcranial direct current stimulation on serial position effect of the 15 words was also examined. The increase in the number of correctly recalled words from the first to the fifth trial was significantly greater in the anodal condition than in the sham condition (P < 0.01). There was a significant difference (P < 0.01) between the anodal and sham conditions in the number of correctly recalled words within the first five words (primacy region) over the second to fifth trial trials, but not in the middle (next five words) or recency (last five words) regions. Anodal transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance and induced the primacy effect in stroke patients.

Short-term anomia training and electrical brain stimulation.

PubMed

Flöel, Agnes; Meinzer, Marcus; Kirstein, Robert; Nijhof, Sarah; Deppe, Michael; Knecht, Stefan; Breitenstein, Caterina

2011-07-01

Language training success in chronic aphasia remains only moderate. Electric brain stimulation may be a viable way to enhance treatment efficacy. In a randomized, double-blind, sham-controlled crossover trial, we assessed if anodal transcranial direct current stimulation compared to cathodal transcranial direct current stimulation and sham stimulation over the right temporo-parietal cortex would improve the success of short-term high-frequency anomia training. Twelve chronic poststroke aphasia patients were studied. Naming outcome was assessed after training and 2 weeks later. All training conditions led to a significant increase in naming ability, which was retained for at least 2 weeks after the end of the training. Application of anodal transcranial direct current stimulation significantly enhanced the overall training effect compared to sham stimulation. Baseline naming ability significantly predicted anodal transcranial direct current stimulation effects. Anodal transcranial direct current stimulation applied over the nonlanguage dominant hemisphere can enhance language training outcome in chronic aphasia. Clinical Trial Registration- URL: www.clinicaltrials.gov/. Unique identifier: NCT00822068.

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.

Transcranial direct current stimulation for motor recovery of upper limb function after stroke.

PubMed

Lüdemann-Podubecká, Jitka; Bösl, Kathrin; Rothhardt, Sandra; Verheyden, Geert; Nowak, Dennis Alexander

2014-11-01

Changes in neural processing after stroke have been postulated to impede recovery from stroke. Transcranial direct current stimulation has the potential to alter cortico-spinal excitability and thereby might be beneficial in stroke recovery. We review the pertinent literature prior to 30/09/2013 on transcranial direct current stimulation in promoting motor recovery of the affected upper limb after stroke. We found overall 23 trials (they included 523 participants). All stimulation protocols pride on interhemispheric imbalance model. In a comparative approach, methodology and effectiveness of (a) facilitation of the affected hemisphere, (b) inhibition of the unaffected hemisphere and (c) combined application of transcranial direct current stimulation over the affected and unaffected hemispheres to treat impaired hand function after stroke are presented. Transcranial direct current stimulation is associated with improvement of the affected upper limb after stroke, but current evidence does not support its routine use. Copyright © 2014 Elsevier Ltd. All rights reserved.

Long-Term Efficacy of Constant Current Deep Brain Stimulation in Essential Tremor.

PubMed

Rezaei Haddad, Ali; Samuel, Michael; Hulse, Natasha; Lin, Hsin-Ying; Ashkan, Keyoumars

2017-07-01

Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the outcomes of constant current deep brain stimulation in the treatment of essential tremor. This study aimed to evaluate the long-term efficacy of ventralis intermedius constant current deep brain stimulation in patients diagnosed with essential tremor. Essential tremor patients implanted with constant current deep brain stimulation for a minimum of three years were evaluated. Clinical outcomes were assessed using the Fahn-Tolosa-Marin tremor rating scale at baseline and postoperatively at the time of evaluation. The quality of life in the patients was assessed using the Quality of Life in Essential Tremor questionnaire. Ten patients were evaluated with a median age at evaluation of 74 years (range 66-79) and a mean follow up time of 49.7 (range 36-78) months since starting stimulation. Constant current ventralis intermedius deep brain stimulation was well tolerated and effective in all patients with a mean score improvement from 50.7 ± 5.9 to 17.4 ± 5.7 (p = 0.0020) in the total Fahn-Tolosa-Marin rating scale score (65.6%). Furthermore, the total combined mean Quality of Life in Essential Tremor score was improved from 56.2 ± 4.9 to 16.8 ± 3.5 (p value = 0.0059) (70.1%). This report shows that long-term constant current ventralis intermedius deep brain stimulation is a safe and effective intervention for essential tremor patients. © 2017 International Neuromodulation Society.

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

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.

Extracorporeal Stimulation of Sacral Nerve Roots for Observation of Pelvic Autonomic Nerve Integrity: Description of a Novel Methodological Setup.

PubMed

Moszkowski, Tomasz; Kauff, Daniel W; Wegner, Celine; Ruff, Roman; Somerlik-Fuchs, Karin H; Kruger, Thilo B; Augustyniak, Piotr; Hoffmann, Klaus-Peter; Kneist, Werner

2018-03-01

Neurophysiologic monitoring can improve autonomic nerve sparing during critical phases of rectal cancer surgery. To develop a system for extracorporeal stimulation of sacral nerve roots. Dedicated software controlled a ten-electrode stimulation array by switching between different electrode configurations and current levels. A built-in impedance and current level measurement assessed the effectiveness of current injection. Intra-anal surface electromyography (sEMG) informed on targeting the sacral nerve roots. All tests were performed on five pig specimens. During switching between electrode configurations, the system delivered 100% of the set current (25 mA, 30 Hz, 200 μs cathodic pulses) in 93% of 250 stimulation trains across all specimens. The impedance measured between single stimulation array contacts and corresponding anodes across all electrode configurations and specimens equaled 3.7 ± 2.5 kΩ. The intra-anal sEMG recorded a signal amplitude increase as previously observed in the literature. When the stimulation amplitude was tested in the range from 1 to 21 mA using the interconnected contacts of the stimulation array and the intra-anal anode, the impedance remained below 250 Ω and the system delivered 100% of the set current in all cases. Intra-anal sEMG showed an amplitude increase for current levels exceeding 6 mA. The system delivered stable electric current, which was proved by built-in impedance and current level measurements. Intra-anal sEMG confirmed the ability to target the branches of the autonomous nervous system originating from the sacral nerve roots. Stimulation outside of the operative field during rectal cancer surgery is feasible and may improve the practicality of pelvic intraoperative neuromonitoring.

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

Intensity coding in electric hearing: effects of electrode configurations and stimulation waveforms.

PubMed

Chua, Tiffany Elise H; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were five Clarion cochlear implant users. For each subject, data from apical, middle, and basal electrode positions were collected when possible. Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen.

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…

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.

Brain Stimulation and the Role of the Right Hemisphere in Aphasia Recovery.

PubMed

Turkeltaub, Peter E

2015-11-01

Aphasia is a common consequence of left hemisphere stroke and causes a disabling loss of language and communication ability. Current treatments for aphasia are inadequate, leaving a majority of aphasia sufferers with ongoing communication difficulties for the rest of their lives. In the past decade, two forms of noninvasive brain stimulation, repetitive transcranial magnetic stimulation and transcranial direct current stimulation, have emerged as promising new treatments for aphasia. The most common brain stimulation protocols attempt to inhibit the intact right hemisphere based on the hypothesis that maladaptive activity in the right hemisphere limits language recovery in the left. There is now sufficient evidence to demonstrate that this approach, at least for repetitive transcranial magnetic stimulation, improves specific language abilities in aphasia. However, the biological mechanisms that produce these behavioral improvements remain poorly understood. Taken in the context of the larger neurobiological literature on aphasia recovery, the role of the right hemisphere in aphasia recovery remains unclear. Additional research is needed to understand biological mechanisms of recovery, in order to optimize brain stimulation treatments for aphasia. This article summarizes the current evidence on noninvasive brain stimulation methods for aphasia and the neuroscientific considerations surrounding treatments using right hemisphere inhibition. Suggestions are provided for further investigation and for clinicians whose patients ask about brain stimulation treatments for aphasia.

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.

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.

Feasibility of transcranial direct current stimulation use in children aged 5 to 12 years.

PubMed

Andrade, Agnes Carvalho; Magnavita, Guilherme Moreira; Allegro, Juleilda Valéria Brasil Nunes; Neto, Carlos Eduardo Borges Passos; Lucena, Rita de Cássia Saldanha; Fregni, Felipe

2014-10-01

Transcranial direct current stimulation is a noninvasive brain stimulation technique that has been studied for the treatment of neuropsychiatric disorders in adults, with minimal side effects. The objective of this study is to report the feasibility, tolerability, and the short-term adverse effects of transcranial direct current stimulation in children from 5 to 12 years of age. It is a naturalistic study of 14 children who underwent 10 sessions of transcranial direct current stimulation as an alternative, off-label, and open-label treatment for various languages disorders. Frequency, intensity, adverse effects, and perception of improvement reported by parents were collected. The main side effects detected were tingling (28.6%) and itching (28.6%), acute mood changes (42.9%), and irritability (35.7%). Transcranial direct current stimulation is a feasible and tolerable technique in children, although studies regarding plastic and cognitive changes in children are needed to confirm its safety. In conclusion, this is a naturalistic report in which we considered transcranial direct current stimulation as feasible in children. © The Author(s) 2013.

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.

Non-invasive brain stimulation: a new strategy to improve neurorehabilitation after stroke?

PubMed

Hummel, Friedhelm C; Cohen, Leonardo G

2006-08-01

Motor impairment resulting from chronic stroke can have extensive physical, psychological, financial, and social implications despite available neurorehabilitative treatments. Recent studies in animals showed that direct epidural stimulation of the primary motor cortex surrounding a small infarct in the lesioned hemisphere (M1(lesioned hemisphere)) elicits improvements in motor function. In human beings, proof of principle studies from different laboratories showed that non-invasive transcranial magnetic stimulation and direct current stimulation that upregulate excitability within M1(lesioned hemisphere) or downregulate excitability in the intact hemisphere (M1(intact hemisphere)) results in improvement in motor function in patients with stroke. Possible mechanisms mediating these effects can include the correction of abnormally persistent interhemispheric inhibitory drive from M1(intact hemisphere) to M1(lesioned hemisphere) in the process of generation of voluntary movements by the paretic hand, a disorder correlated with the magnitude of impairment. In this paper we review these mechanistically oriented interventional approaches. WHAT NEXT?: These findings suggest that transcranial magnetic stimulation and transcranial direct current stimulation could develop into useful adjuvant strategies in neurorehabilitation but have to be further assessed in multicentre clinical trials.

Optimized multi-electrode stimulation increases focality and intensity at target

NASA Astrophysics Data System (ADS)

Dmochowski, Jacek P.; Datta, Abhishek; Bikson, Marom; Su, Yuzhuo; Parra, Lucas C.

2011-08-01

Transcranial direct current stimulation (tDCS) provides a non-invasive tool to elicit neuromodulation by delivering current through electrodes placed on the scalp. The present clinical paradigm uses two relatively large electrodes to inject current through the head resulting in electric fields that are broadly distributed over large regions of the brain. In this paper, we present a method that uses multiple small electrodes (i.e. 1.2 cm diameter) and systematically optimize the applied currents to achieve effective and targeted stimulation while ensuring safety of stimulation. We found a fundamental trade-off between achievable intensity (at the target) and focality, and algorithms to optimize both measures are presented. When compared with large pad-electrodes (approximated here by a set of small electrodes covering 25cm2), the proposed approach achieves electric fields which exhibit simultaneously greater focality (80% improvement) and higher target intensity (98% improvement) at cortical targets using the same total current applied. These improvements illustrate the previously unrecognized and non-trivial dependence of the optimal electrode configuration on the desired electric field orientation and the maximum total current (due to safety). Similarly, by exploiting idiosyncratic details of brain anatomy, the optimization approach significantly improves upon prior un-optimized approaches using small electrodes. The analysis also reveals the optimal use of conventional bipolar montages: maximally intense tangential fields are attained with the two electrodes placed at a considerable distance from the target along the direction of the desired field; when radial fields are desired, the maximum-intensity configuration consists of an electrode placed directly over the target with a distant return electrode. To summarize, if a target location and stimulation orientation can be defined by the clinician, then the proposed technique is superior in terms of both focality and intensity as compared to previous solutions and is thus expected to translate into improved patient safety and increased clinical efficacy.

Intensity coding in electric hearing: Effects of electrode configurations and stimulation waveforms

PubMed Central

Chua, Tiffany Elise H.; Bachman, Mark; Zeng, Fan-Gang

2011-01-01

Objectives Current cochlear implants typically stimulate the auditory nerve with biphasic pulses and monopolar electrode configurations. Tripolar stimulation can increase spatial selectivity and potentially improve place pitch related perception, but requires higher current levels to elicit the same loudness as monopolar stimulation. The present study combined delayed pseudomonophonasic pulses, which produce lower thresholds, with tripolar stimulation in an attempt to solve the power-performance tradeoff problem. Design The present study systematically measured thresholds, dynamic range, loudness growth, and intensity discrimination using either biphasic or delayed pseudomonophonasic pulses under both monopolar and tripolar stimulation. Participants were 5 Clarion cochlear implant users. For each subject, data from apical, middle and basal electrode positions were collected when possible. Results Compared with biphasic pulses, delayed pseudomonophonasic pulses increased the dynamic range by lowering thresholds while maintaining comparable maximum allowable levels under both electrode configurations. However, delayed pseudomonophonasic pulses did not change the shape of loudness growth function and actually increased intensity discrimination limens, especially at lower current levels. Conclusions The present results indicate that delayed pseudomonophonasic pulses coupled with tripolar stimulation cannot provide significant power savings, nor can it increase the functional dynamic range. Whether this combined stimulation could improve functional spectral resolution remains to be seen. PMID:21610498

Surmounting retraining limits in musicians' dystonia by transcranial stimulation.

PubMed

Furuya, Shinichi; Nitsche, Michael A; Paulus, Walter; Altenmüller, Eckart

2014-05-01

Abnormal cortical excitability is evident in various movement disorders that compromise fine motor control. Here we tested whether skilled finger movements can be restored in musicians with focal hand dystonia through behavioral training assisted by transcranial direct current stimulation to the motor cortex of both hemispheres. The bilateral motor cortices of 20 pianists (10 with focal dystonia, 10 healthy controls) were electrically stimulated noninvasively during bimanual mirrored finger movements. We found improvement in the rhythmic accuracy of sequential finger movements with the affected hand during and after cathodal stimulation over the affected cortex and simultaneous anodal stimulation over the unaffected cortex. The improvement was retained 4 days after intervention. Neither a stimulation with the reversed montage of electrodes nor sham stimulation yielded any improvement. Furthermore, the amount of improvement was positively correlated with the severity of the symptoms. Bihemispheric stimulation without concurrent motor training failed to improve fine motor control, underlining the importance of combined retraining and stimulation for restoring the dystonic symptoms. For the healthy pianists, none of the stimulation protocols enhanced movement accuracy. These results suggest a therapeutic potential of behavioral training assisted by bihemispheric, noninvasive brain stimulation in restoring fine motor control in focal dystonia. © 2014 American Neurological Association.

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.

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.

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.

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.

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.

Direct current stimulation of titanium interbody fusion devices in primates.

PubMed

Cook, Stephen D; Patron, Laura P; Christakis, Petros M; Bailey, Kirk J; Banta, Charles; Glazer, Paul A

2004-01-01

The fusion rate for anterior lumbar interbody fusion (ALIF) varies widely with the use of different interbody devices and bone graft options. Adjunctive techniques such as electrical stimulation may improve the rate of bony fusion. To determine if direct current (DC) electrical stimulation of a metallic interbody fusion device enhanced the incidence or extent of anterior bony fusion. ALIF was performed using titanium alloy interbody fusion devices with and without adjunctive DC electrical stimulation in nonhuman primates. ALIF was performed through an anterolateral approach in 35 macaques with autogenous bone graft and either a titanium alloy (Ti-6Al-4V) fusion device or femoral allograft ring. The fusion devices of 19 animals received high (current density 19.6 microA/cm2) or low (current density 5.4 microA/cm2) DC electrical stimulation using an implanted generator for a 12- or 26-week evaluation period. Fusion sites were studied using serial radiographs, computed tomography imaging, nondestructive mechanical testing and qualitative and semiquantitative histology. Fusion was achieved with the titanium fusion device and autogenous bone graft. At 12 weeks, the graft was consolidating and early to moderate bridging callus was observed in and around the device. By 26 weeks, the anterior callus formation was more advanced with increased evidence of bridging trabeculations and early bone remodeling. The callus formation was not as advanced or abundant for the allograft ring group. Histology revealed the spinal fusion device had an 86% incidence of bony fusion at 26 weeks compared with a 50% fusion rate for the allograft rings. DC electrical stimulation of the fusion device had a positive effect on anterior interbody fusion by increasing both the presence and extent of bony fusion in a current density-dependent manner. Adjunctive DC electrical stimulation of the fusion device improved the rate and extent of bony fusion compared with a nonstimulated device. The fusion device was equivalent to or better than the femoral allograft ring in all evaluations. The use of adjunctive direct current electrical stimulation may provide a means of improving anterior interbody fusion.

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.

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.

Non-invasive cortical stimulation improves post-stroke attention decline.

PubMed

Kang, Eun Kyoung; Baek, Min Jae; Kim, Sangyun; Paik, Nam-Jong

2009-01-01

Attention decline after stroke is common and hampers the rehabilitation process, and non-invasive transcranial direct current stimulation (tDCS) has the potential to elicit behavioral changes by modulating cortical excitability. The authors tested the hypothesis that a single session of non-invasive cortical stimulation with excitatory anodal tDCS applied to the left dorsolateral prefrontal cortex (DLPFC) can improve attention in stroke patients. Ten patients with post-stroke cognitive decline (MMSE 25) and 10 age-matched healthy controls participated in this double blind, sham-controlled, crossover study involving the administration of real (2 mA for 20 min) or sham stimulation (2 mA for 1 min) to the left DLPFC. Attention was measured using a computerized Go/No-Go test before and after intervention. Improvements in accuracy and speed after stimulation relative to baseline were compared for real and sham stimulations. In healthy controls, no significant improvement in Go/No-Go test was observed after either real or sham stimulation. However, in stroke patients, tDCS led to a significant improvement in response accuracy at 1 hour post-stimulation relative to baseline, and this improvement was maintained until 3 hours post-stimulation (P< 0.05), whereas sham stimulation did not lead to a significant improvement in response accuracy (P> 0.05). Changes in reaction times were comparable for the two stimulations (P> 0.05). Non invasive anodal tDCS applied to the left DLPFC was found to improve attention versus sham stimulation in stroke patients, which suggests that non-invasive cortical intervention could potentially be used during rehabilitative training to improve attention.

Transcranial Direct Current Stimulation in Post-stroke Chronic Aphasia: The Impact of Baseline Severity and Task Specificity in a Pilot Sample

PubMed Central

Norise, Catherine; Sacchetti, Daniela; Hamilton, Roy

2017-01-01

Emerging evidence suggests that transcranial direct current stimulation (tDCS) can improve aspects of language production in persons with chronic non-fluent aphasia due to left hemisphere stroke. However, to date, studies exploring factors that predict response to tDCS in this or any patient population remain sparse, as are studies that investigate the specific aspects of language performance that are most responsive to stimulation. The current study explored factors that could predict recovery of language fluency and which aspects of language fluency could be expected to improve with the identified factor(s). We report nine patients who demonstrated deficits in fluency as assessed using the Cookie Theft picture description task of the Boston Diagnostic Aphasia Examination. In the treatment condition, subjects received a 2.0 mA current through 5 cm × 5 cm electrodes for 20 min at a site previously shown to elicit a patient-dependent optimal response to tDCS. They were then tested 2-weeks and 2-months after treatment. In the sham condition, a subset of these subjects were tested on the same protocol with sham instead of real tDCS. The current study assessed language fluency improvements in measures of production at the word-level and sentence level, grammatical accuracy, and lexical selection as a function of baseline aphasia severity. A more severe baseline language profile was associated with larger improvements in fluency at the word-level after real tDCS but not sham stimulation. These improvements were maintained at the 2-week follow-up. The results suggest that for at least some outcome measures, baseline severity may be an important factor in predicting the response to tDCS in patients with chronic non-fluent aphasia. Moving forward, the ability to identify patient factors that can predict response could help refine strategies for the administration of therapeutic tDCS, focusing attention on those patients most likely to benefit from stimulation. PMID:28611609

Preliminary investigation of the effects of γ-tACS on working memory in schizophrenia.

PubMed

Hoy, Kate E; Whitty, Dean; Bailey, Neil; Fitzgerald, Paul B

2016-10-01

Working memory impairment in schizophrenia has been strongly associated with abnormalities in gamma oscillations within the dorsolateral prefrontal cortex (DLFPC). We recently published the first ever study showing that anodal transcranial direct current stimulation (tDCS) to the left DLPFC was able to significantly improve working memory in schizophrenia and did so seemingly via restoring normal gamma oscillatory function. Transcranial alternating current stimulation (tACS) is a form of electrical brain stimulation that delivers stimulation at a specific frequency and has been shown to entrain endogenous cortical oscillations. Therefore, gamma (γ) tACS may be even more effective than tDCS in improving working memory in schizophrenia. In a randomized repeated-measures study we compared the effects of γ-tACS, tDCS and sham stimulation on the performance of the two back working memory tasks in ten patients with schizophrenia. There was a significant time by stimulation interaction, with tDCS and sham showing trend-level improvements in working memory, while γ-tACS, contrary to our hypothesis, showed no change. The results are discussed in light of posited divergent effects of tACS and tDCS on the pathophysiology of working memory impairment in schizophrenia.

From amusic to musical?--Improving pitch memory in congenital amusia with transcranial alternating current stimulation.

PubMed

Schaal, Nora K; Pfeifer, Jasmin; Krause, Vanessa; Pollok, Bettina

2015-11-01

Brain imaging studies highlighted structural differences in congenital amusia, a life-long perceptual disorder that is associated with pitch perception and pitch memory deficits. A functional anomaly characterized by decreased low gamma oscillations (30-40 Hz range) in the right dorsolateral prefrontal cortex (DLPFC) during pitch memory has been revealed recently. Thus, the present study investigates whether applying transcranial alternating current stimulation (tACS) at 35 Hz to the right DLPFC would improve pitch memory. Nine amusics took part in two tACS sessions (either 35 Hz or 90 Hz) and completed a pitch and visual memory task before and during stimulation. 35 Hz stimulation facilitated pitch memory significantly. No modulation effects were found with 90 Hz stimulation or on the visual task. While amusics showed a selective impairment of pitch memory before stimulation, the performance during 35 Hz stimulation was not significantly different to healthy controls anymore. Taken together, the study shows that modulating the right DLPFC with 35 Hz tACS in congenital amusia selectively improves pitch memory performance supporting the hypothesis that decreased gamma oscillations within the DLPFC are causally involved in disturbed pitch memory and highlight the potential use of tACS to interact with cognitive processes. Copyright © 2015 Elsevier B.V. All rights reserved.

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 effects of transcranial direct current stimulation on tobacco consumption. Several studies have reported a beneficial effect of transcranial direct current stimulation on substance use disorders by reducing craving, impulsivity, and risk-taking behavior, and suggest that transcranial direct current stimulation may be a promising treatment in addiction. However, to date, no studies have included sufficiently large samples and sufficient follow-up to confirm the hypothesis. Results from this large randomized controlled trial will give a better overview of the therapeutic potential of transcranial direct current stimulation in alcohol use disorders. Clinical Trials Gov, NCT02505126 (registration date: July 15 2015).

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. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Anodal transcranial direct current stimulation of the left dorsolateral prefrontal cortex enhances emotion recognition in depressed patients and controls.

PubMed

Brennan, Sean; McLoughlin, Declan M; O'Connell, Redmond; Bogue, John; O'Connor, Stephanie; McHugh, Caroline; Glennon, Mark

2017-05-01

Transcranial direct current stimulation (tDCS) can enhance a range of neuropsychological functions but its efficacy in addressing clinically significant emotion recognition deficits associated with depression is largely untested. A randomized crossover placebo controlled study was used to investigate the effects of tDCS over the left dorsolateral prefrontal cortex (L-DLPFC) on a range of neuropsychological variables associated with depression as well as neural activity in the associated brain region. A series of computerized tests was administered to clinical (n = 17) and control groups (n = 20) during sham and anodal (1.5 mA) stimulation. Anodal tDCS led to a significant main effect for overall emotion recognition (p = .02), with a significant improvement in the control group (p = .04). Recognition of disgust was significantly greater in the clinical group (p = .01). Recognition of anger was significantly improved for the clinical group (p = .04) during anodal stimulation. Differences between groups for each of the six emotions at varying levels of expression found that at 40% during anodal stimulation, happy recognition significantly improved for the clinical group (p = .01). Anger recognition at 80% during anodal stimulation significantly improved for the clinical group (p = .02). These improvements were observed in the absence of any change in psychomotor speed or trail making ability during anodal stimulation. Working memory significantly improved during anodal stimulation for the clinical group but not for controls (p = .03). The tentative findings of this study indicate that tDCS can have a neuromodulatory effect on a range of neuropsychological variables. However, it is clear that there was a wide variation in responses to tDCS and that individual difference and different approaches to testing and stimulation have a significant impact on final outcomes. Nonetheless, tDCS remains a promising tool for future neuropsychological research.

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 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.

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation.

PubMed

Zhu, Ziyan; Tang, Qing; Zeng, Fan-Gang; Guan, Tian; Ye, Datian

2012-01-01

Sharp spatial selectivity is critical to auditory performance, particularly in pitch-related tasks. Most contemporary cochlear implants have employed monopolar stimulation that produces broad electric fields, which presumably contribute to poor pitch and pitch-related performance by implant users. Bipolar or tripolar stimulation can generate focused electric fields but requires higher current to reach threshold and, more interestingly, has not produced any apparent improvement in cochlear-implant performance. The present study addressed this dilemma by measuring psychophysical and physiological spatial selectivity with both broad and focused stimulations in the same cohort of subjects. Different current levels were adjusted by systematically measuring loudness growth for each stimulus, each stimulation mode, and in each subject. Both psychophysical and physiological measures showed that, although focused stimulation produced significantly sharper spatial tuning than monopolar stimulation, it could shift the tuning position or even split the tuning tips. The altered tuning with focused stimulation is interpreted as a result of poor electrode-to-neuron interface in the cochlea, and is suggested to be mainly responsible for the lack of consistent improvement in implant performance. A linear model could satisfactorily quantify the psychophysical and physiological data and derive the tuning width. Significant correlation was found between the individual physiological and psychophysical tuning widths, and the correlation was improved by log-linearly transforming the physiological data to predict the psychophysical data. Because the physiological measure took only one-tenth of the time of the psychophysical measure, the present model is of high clinical significance in terms of predicting and improving cochlear-implant performance. Copyright © 2011 Elsevier B.V. All rights reserved.

Cochlear Implant Spatial Selectivity with Monopolar, Bipolar and Tripolar Stimulation

PubMed Central

Zhu, Ziyan; Tang, Qing; Zeng, Fan-Gang; Guan, Tian; Ye, Datian

2011-01-01

Sharp spatial selectivity is critical to auditory performance, particularly in pitch related tasks. Most contemporary cochlear implants have employed monopolar stimulation that produces broad electric fields, which presumably contribute to poor pitch and pitch-related performance by implant users. Bipolar or tripolar stimulation can generate focused electric fields but requires higher current to reach threshold and, more interestingly, has not produced any apparent improvement in cochlear implant performance. The present study addressed this dilemma by measuring psychophysical and physiological spatial selectivity with both broad and focused stimulations in the same cohort of subjects. Different current levels were adjusted by systematically measuring loudness growth for each stimulus, each stimulation mode, and in each subject. Both psychophysical and physiological measures showed that, although focused stimulation produced significantly sharper spatial tuning than monopolar stimulation, it could shift the tuning position or even split the tuning tips. The altered tuning with focused stimulation is interpreted as a result of poor electrode-to-neuron interface in the cochlea, and is suggested to be mainly responsible for the lack of consistent improvement in implant performance. A linear model could satisfactorily quantify the psychophysical and physiological data and derive the tuning width. Significant correlation was found between the individual physiological and psychophysical tuning widths, and the correlation was improved by log-linearly transforming the physiological data to predict the psychophysical data. Because the physiological measure took only one-tenth of the time of the psychophysical measure, the present model is of high clinical significance in terms of predicting and improving cochlear implant performance. PMID:22138630

Electrical stimulation of anal sphincter or pudendal nerve improves anal sphincter pressure.

PubMed

Damaser, Margot S; Salcedo, Levilester; Wang, Guangjian; Zaszczurynski, Paul; Cruz, Michelle A; Butler, Robert S; Jiang, Hai-Hong; Zutshi, Massarat

2012-12-01

Stimulation of the pudendal nerve or the anal sphincter could provide therapeutic options for fecal incontinence with little involvement of other organs. The goal of this project was to assess the effects of pudendal nerve and anal sphincter stimulation on bladder and anal pressures. Ten virgin female Sprague Dawley rats were randomly allocated to control (n = 2), perianal stimulation (n = 4), and pudendal nerve stimulation (n = 4) groups. A monopolar electrode was hooked to the pudendal nerve or placed on the anal sphincter. Aballoon catheter was inserted into the anus to measure anal pressure, and a catheter was inserted into the bladder via the urethra to measure bladder pressure. Bladder and anal pressures were measured with different electrical stimulation parameters and different timing of electrical stimulation relative to spontaneous anal sphincter contractions. Increasing stimulation current had the most dramatic effect on both anal and bladder pressures. An immediate increase in anal pressure was observed when stimulating either the anal sphincter or the pudendal nerve at stimulation values of 1 mA or 2 mA. No increase in anal pressure was observed for lower current values. Bladder pressure increased at high current during anal sphincter stimulation, but not as much as during pudendal nerve stimulation. Increased bladder pressure during anal sphincter stimulation was due to contraction of the abdominal muscles. Electrical stimulation caused an increase in anal pressures with bladder involvement only at high current. These initial results suggest that electrical stimulation can increase anal sphincter pressure, enhancing continence control.

Interference effects of transcranial direct current stimulation over the right frontal cortex and adrenergic system on conditioned fear.

PubMed

Nasehi, Mohammad; Soltanpour, Reyhaneh; Ebrahimi-Ghiri, Mohaddeseh; Zarrabian, Shahram; Zarrindast, Mohammad-Reza

2017-11-01

The effects of pharmacological interventions on fear memory have widely been studied, but there are very few studies about the effects of brain electrical stimulation on fear memory function. Therefore, our aim was to determine whether anodal/cathodal transcranial direct current stimulation (tDCS) over the right frontal cortex would modify propranolol-induced contextual and auditory fear memory deficits, before or after training. The adult NMRI male mice were randomly assigned into three groups: the sham group, the anodal tDCS group, and the cathodal tDCS group. Fear memories were evaluated using a classical fear conditioning apparatus. While the anodal stimulation did not affect fear retrieval, post-training cathodal stimulation improved fear memory retrieval. Regardless of when propranolol (0.1 mg/kg) was administered, it impaired fear memory retrieval. However, when anodal stimulation and propranolol were applied prior to the training, contextual fear memory retrieval was increased and auditory fear memory was reversed. An enhanced contextual retrieval was also observed when propranolol was administered prior to the training and stimulation occurred after the training. Only when the stimulation occurred prior to the training and propranolol was administered after the training was there a selective improvement in contextual fear memory retrieval, leaving the auditory fear memory retrieval impaired. Interestingly, cathodal stimulation improved the effects of propranolol on auditory fear memory only when it occurred prior to the training. The results highlight possible improving effects for anodal/cathodal tDCS on propranolol-induced deficits on fear memories. The timing of the interventions related to the specific phases of memory formation is important in modulating fear behaviors.

Use of Vagus Nerve Stimulator on Children With Primary Generalized Epilepsy.

PubMed

Welch, William P; Sitwat, Bilal; Sogawa, Yoshimi

2018-06-01

To describe the response to vagus nerve stimulator (VNS) in otherwise neurotypical children with medically intractable primary generalized epilepsy. Retrospective chart review of patients who underwent vagus nerve stimulator surgery between January 2011 and December 2015. Eleven patients were identified. Median follow-up duration was 2.5 years (1.2-8.4 years). Prior to vagus nerve stimulator surgery, all patients had at least 1 seizure per week, and 7/11 (64%) had daily seizures. At 1-year follow-up after vagus nerve stimulator, 7/11 (64%) reported improved seizure frequency and 6/11 (55%) reported fewer than 1 seizure per month. Three patients (27%) reported complications related to vagus nerve stimulator surgery, and no patients required device removal. In children with medically intractable primary generalized epilepsy, vagus nerve stimulator is well tolerated and appears to lead to improvement in seizure frequency. Improvement was not attributable to epilepsy classification, age at vagus nerve stimulator implantation, output current, duty cycle, or follow-up duration.

Efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia.

PubMed

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

2017-06-01

Provoked vestibulodynia is a highly prevalent condition characterized by acute recurrent pain located at the vaginal entrance in response to pressure application or attempted vaginal penetration. Despite a wide variety of treatments offered to women with provoked vestibulodynia, a high proportion of women are refractory to conventional treatment. Transcranial direct-current stimulation is a noninvasive brain stimulation technique that has been shown effective for improving various chronic pain conditions. Growing evidence suggests that the central nervous system could play a key role in provoked vestibulodynia. Targeting the central nervous system could therefore be a promising treatment for women with provoked vestibulodynia. The purpose of this study was to evaluate and compare the efficacy of active and sham transcranial direct-current stimulation in reducing pain intensity during intercourse in patients with provoked vestibulodynia. We conducted a triple-blind, parallel-group, randomized controlled trial. Women aged 17-45 years diagnosed with provoked vestibulodynia by a gynecologist using a validated protocol were randomized to 10 sessions of either active transcranial direct-current stimulation (intensity = 2 mA) or 10 sessions of sham transcranial direct-current stimulation, over a 2-week period. Both active and sham transcranial direct-current stimulation were applied for 20 minutes, with the anode positioned over the primary motor cortex, and the cathode over the contralateral supraorbital area. Outcome measures were collected at baseline, 2 weeks after treatment, and at 3-month follow-up by an evaluator blinded to group assignment. The primary objective was to assess pain intensity during intercourse, using a numerical rating scale. Secondary outcomes focused on sexual function and distress, vestibular sensitivity, psychological distress, treatment satisfaction, and patient impression of change. Statistical analyses were conducted on the intention-to-treat basis, and treatment effects were evaluated using a mixed linear model for repeated measures. A total of 40 patients were randomly assigned to receive either active (n = 20) or sham (n = 20) transcranial direct-current stimulation treatments from November 2014 through February 2016. Baseline characteristics were similar between the active and sham transcranial direct-current stimulation groups. In full compliance with the study protocol, every participant followed all courses of the study treatment, including assessments at 2-week and 3-month follow-up. Pain during sexual intercourse was not significantly different between active and sham treatment groups 2 weeks after treatment (P = .84) and at follow-up (P = .09). Mean baseline and 2-week assessment pain intensity were, respectively, 6.8 (95% confidence interval, 5.9-7.7) and 5.6 (95% confidence interval, 4.7-6.5) for active transcranial direct-current stimulation (P = .03) vs 7.5 (95% confidence interval, 6.6-8.4) and 5.7 (95% confidence interval, 4.8-6.6) for sham transcranial direct-current stimulation (P = .001). Nonsignificant differences between the 2 groups were also found in their sexual function and distress after treatment (P > .20) and at follow-up (P > .10). Overall, at 2-week assessment 68% assigned to active transcranial direct-current stimulation reported being very much, much, or slightly improved compared to 65% assigned to sham transcranial direct-current stimulation (P = .82), and still comparable at follow-up: 42% vs 65%, respectively (P = .15). Findings suggest that active transcranial direct-current stimulation is not more effective than sham transcranial direct-current stimulation for reducing pain in women with provoked vestibulodynia. Likewise, no significant effects were found on sexual function, vestibular sensitivity, or psychological distress. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

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.

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

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.

An energy-efficient, adiabatic electrode stimulator with inductive energy recycling and feedback current regulation.

PubMed

Arfin, Scott K; Sarpeshkar, Rahul

2012-02-01

In this paper, we present a novel energy-efficient electrode stimulator. Our stimulator uses inductive storage and recycling of energy in a dynamic power supply. This supply drives an electrode in an adiabatic fashion such that energy consumption is minimized. It also utilizes a shunt current-sensor to monitor and regulate the current through the electrode via feedback, thus enabling flexible and safe stimulation. Since there are no explicit current sources or current limiters, wasteful energy dissipation across such elements is naturally avoided. The dynamic power supply allows efficient transfer of energy both to and from the electrode and is based on a DC-DC converter topology that we use in a bidirectional fashion in forward-buck or reverse-boost modes. In an exemplary electrode implementation intended for neural stimulation, we show how the stimulator combines the efficiency of voltage control and the safety and accuracy of current control in a single low-power integrated-circuit built in a standard .35 μm CMOS process. This stimulator achieves a 2x-3x reduction in energy consumption as compared to a conventional current-source-based stimulator operating from a fixed power supply. We perform a theoretical analysis of the energy efficiency that is in accord with experimental measurements. This theoretical analysis reveals that further improvements in energy efficiency may be achievable with better implementations in the future. Our electrode stimulator could be widely useful for neural, cardiac, retinal, cochlear, muscular and other biomedical implants where low power operation is important.

New modalities of brain stimulation for stroke rehabilitation

PubMed Central

Lucas, T. H.; Carey, J. R.; Fetz, E. E.

2014-01-01

Stroke is a leading cause of disability, and the number of stroke survivors continues to rise. Traditional neurorehabilitation strategies aimed at restoring function to weakened limbs provide only modest benefit. New brain stimulation techniques designed to augment traditional neurorehabilitation hold promise for reducing the burden of stroke-related disability. Investigators discovered that repetitive transcranial magnetic stimulation (rTMS), trans-cranial direct current stimulation (tDCS), and epidural cortical stimulation (ECS) can enhance neural plasticity in the motor cortex post-stroke. Improved outcomes may be obtained with activity-dependent stimulation, in which brain stimulation is contingent on neural or muscular activity during normal behavior. We review the evidence for improved motor function in stroke patients treated with rTMS, tDCS, and ECS and discuss the mediating physiological mechanisms. We compare these techniques to activity-dependent stimulation, discuss the advantages of this newer strategy for stroke rehabilitation, and suggest future applications for activity-dependent brain stimulation. PMID:23192336

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 feasibility of, acceptability of and adherence with a clinical trial protocol to administer this treatment to pregnant women with moderate to severe depression. Results from this pilot study will guide the development of a larger multicentre trial to definitively test the efficacy and safety of transcranial direct current stimulation for pregnant women with depression. Clinical Trials Gov NCT02116127.

Enhancing motor performance improvement by personalizing non-invasive cortical stimulation with concurrent functional near-infrared spectroscopy and multi-modal motor measurements

NASA Astrophysics Data System (ADS)

Khan, Bilal; Hodics, Timea; Hervey, Nathan; Kondraske, George; Stowe, Ann; Alexandrakis, George

2015-03-01

Transcranial direct current stimulation (tDCS) is a non-invasive cortical stimulation technique that can facilitate task specific plasticity that can improve motor performance. Current tDCS interventions uniformly apply a chosen electrode montage to a subject population without personalizing electrode placement for optimal motor gains. We propose a novel perturbation tDCS (ptDCS) paradigm for determining a personalized electrode montage in which tDCS intervention yields maximal motor performance improvements during stimulation. PtDCS was applied to ten healthy adults and five stroke patients with upper hemiparesis as they performed an isometric wrist flexion task with their non-dominant arm. Simultaneous recordings of torque applied to a stationary handle, muscle activity by electromyography (EMG), and cortical activity by functional near-infrared spectroscopy (fNIRS) during ptDCS helped interpret how cortical activity perturbations by any given electrode montage related to changes in muscle activity and task performance quantified by a Reaction Time (RT) X Error product. PtDCS enabled quantifying the effect on task performance of 20 different electrode pair montages placed over the sensorimotor cortex. Interestingly, the electrode montage maximizing performance in all healthy adults did not match any of the ones being explored in current literature as a means of improving the motor performance of stroke patients. Furthermore, the optimal montage was found to be different in each stroke patient and the resulting motor gains were very significant during stimulation. This study supports the notion that task-specific ptDCS optimization can lend itself to personalizing the rehabilitation of patients with brain injury.

Theta-burst microstimulation in the human entorhinal area improves memory specificity.

PubMed

Titiz, Ali S; Hill, Michael R H; Mankin, Emily A; M Aghajan, Zahra; Eliashiv, Dawn; Tchemodanov, Natalia; Maoz, Uri; Stern, John; Tran, Michelle E; Schuette, Peter; Behnke, Eric; Suthana, Nanthia A; Fried, Itzhak

2017-10-24

The hippocampus is critical for episodic memory, and synaptic changes induced by long-term potentiation (LTP) are thought to underlie memory formation. In rodents, hippocampal LTP may be induced through electrical stimulation of the perforant path. To test whether similar techniques could improve episodic memory in humans, we implemented a microstimulation technique that allowed delivery of low-current electrical stimulation via 100 μm -diameter microelectrodes. As thirteen neurosurgical patients performed a person recognition task, microstimulation was applied in a theta-burst pattern, shown to optimally induce LTP. Microstimulation in the right entorhinal area during learning significantly improved subsequent memory specificity for novel portraits; participants were able both to recognize previously-viewed photos and reject similar lures. These results suggest that microstimulation with physiologic level currents-a radical departure from commonly used deep brain stimulation protocols-is sufficient to modulate human behavior and provides an avenue for refined interrogation of the circuits involved in human memory.

Enhanced motor skill acquisition in the non-dominant upper extremity using intermittent theta burst stimulation and transcranial direct current stimulation.

PubMed

Butts, Raymond J; Kolar, Melissa B; Newman-Norlund, Roger D

2014-01-01

Individuals suffering from motor impairments often require physical therapy (PT) to help improve their level of function. Previous investigations suggest that both intermittent theta burst stimulation (iTBS) and bihemispheric transcranial direct current stimulation (tDCS) may increase the speed and extent of motor learning/relearning. The purpose of the current study was to explore the feasibility and effectiveness of a novel, non-invasive brain stimulation approach that combined an iTBS primer, and bihemispheric stimulation coupled with motor training. We hypothesized that individuals exposed to this novel treatment would make greater functional improvements than individuals undergoing sham stimulation when tested immediately following, 24-h, and 7-days post-training. A total of 26 right-handed, healthy young adults were randomly assigned to either a treatment (n = 15) or control group (n = 12). iTBS (20 trains of 10 pulse triplets each delivered at 80% active motor threshold (AMT) / 50 Hz over 191.84 s) and bihemispheric tDCS (1.0 ma for 20 min) were used as a primer to, and in conjunction with, 20 min of motor training, respectively. Our primary outcome measure was performance on the Jebsen-Taylor Hand Function (JTHF) test. Participants tolerated the combined iTBS/bihemispheric stimulation treatment without complaint. While performance gains in the sham and stimulation group were not significant immediately after training, they were nearly significant 24-h post training (p = 0.055), and were significant at 7-days post training (p < 0.05). These results suggest that the combined iTBS/bihemispheric stimulation protocol is both feasible and effective. Future research should examine the mechanistic explanation of this approach as well as the potential of using this approach in clinical populations.

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.

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. Published by Elsevier Inc.

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 complex motor function that are the most improved by transcranial direct current stimulation in patients with hemiparesis. It is the first essential step towards validating this technique as a treatment, coupled with task-oriented training. ClinicalTrials.gov, ID: NCT02134158 . First received on 18 December 2013; last updated on 14 September 2016. Other study ID numbers: P120135 / AOM12126, 2013-A00952-43.

The treatment of Parkinson's disease with deep brain stimulation: current issues.

PubMed

Moldovan, Alexia-Sabine; Groiss, Stefan Jun; Elben, Saskia; Südmeyer, Martin; Schnitzler, Alfons; Wojtecki, Lars

2015-07-01

Deep brain stimulation has become a well-established symptomatic treatment for Parkinson's disease during the last 25 years. Besides improving motor symptoms and long-term motor complications, positive effects on patients' mobility, activities of daily living, emotional well-being and health-related quality of life have been recognized. Apart from that, numerous clinical trials analyzed effects on non-motor symptoms and side effects of deep brain stimulation. Several technical issues and stimulation paradigms have been and are still being developed to optimize the therapeutic effects, minimize the side effects and facilitate handling. This review summarizes current therapeutic issues, i.e., patient and target selection, surgical procedure and programming paradigms. In addition it focuses on neuropsychological effects and side effects of deep brain stimulation.

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…

Long-term effects of stimulant treatment on ADHD symptoms, social-emotional functioning, and cognition.

PubMed

Schweren, Lizanne; Hoekstra, Pieter; van Lieshout, Marloes; Oosterlaan, Jaap; Lambregts-Rommelse, Nanda; Buitelaar, Jan; Franke, Barbara; Hartman, Catharina

2018-03-13

Methodological and ethical constraints have hampered studies into long-term lasting outcomes of stimulant treatment in individuals with attention-deficit/hyperactivity disorder (ADHD). Lasting effects may be beneficial (i.e. improved functioning even when treatment is temporarily ceased) or detrimental (i.e. worse functioning while off medication), but both hypotheses currently lack empirical support. Here we investigate whether stimulant treatment history predicts long-term development of ADHD symptoms, social-emotional functioning or cognition, measured after medication wash-out. ADHD symptoms, social-emotional functioning and cognitive test performance were measured twice, 6 years apart, in two ADHD groups (stimulant-treated versus not stimulant-treated between baseline and follow-up). Groups were closely matched on baseline clinical and demographic variables (n = 148, 58% male, age = 11.1). A matched healthy control group was included for reference. All but two outcome measures (emotional problems and prosocial behaviour) improved between baseline and follow-up. Improvement over time in the stimulant-treated group did not differ from improvement in the not stimulant-treated group on any outcome measure. Stimulant treatment is not associated with the long-term developmental course of ADHD symptoms, social-emotional functioning, motor control, timing or verbal working memory. Adolescence is characterised by clinical improvement regardless of stimulant treatment during that time. These findings are an important source to inform the scientific and public debate.

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 target engagement when testing stimulation-based interventions for the treatment of mental disorders. Published by Elsevier Inc.

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, employ computational modeling, and demonstrate target engagement when testing stimulation-based interventions for the treatment of mental disorders. PMID:29398575

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.

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

Individualized treatment with transcranial direct current stimulation in patients with chronic non-fluent aphasia due to stroke

PubMed Central

Shah-Basak, Priyanka P.; Norise, Catherine; Garcia, Gabriella; Torres, Jose; Faseyitan, Olufunsho; Hamilton, Roy H.

2015-01-01

While evidence suggests that transcranial direct current stimulation (tDCS) may facilitate language recovery in chronic post-stroke aphasia, individual variability in patient response to different patterns of stimulation remains largely unexplored. We sought to characterize this variability among chronic aphasic individuals, and to explore whether repeated stimulation with an individualized optimal montage could lead to persistent reduction of aphasia severity. In a two-phase study, we first stimulated patients with four active montages (left hemispheric anode or cathode; right hemispheric anode or cathode) and one sham montage (Phase 1). We examined changes in picture naming ability to address (1) variability in response to different montages among our patients, and (2) whether individual patients responded optimally to at least one montage. During Phase 2, subjects who responded in Phase 1 were randomized to receive either real-tDCS or to receive sham stimulation (10 days); patients who were randomized to receive sham stimulation first were then crossed over to receive real-tDCS (10 days). In both phases, 2 mA tDCS was administered for 20 min per real-tDCS sessions and patients performed a picture naming task during stimulation. Patients' language ability was re-tested after 2-weeks and 2-months following real and sham tDCS in Phase 2. In Phase 1, despite considerable individual variability, the greatest average improvement was observed after left-cathodal stimulation. Seven out of 12 subjects responded optimally to at least one montage as demonstrated by transient improvement in picture-naming. In Phase 2, aphasia severity improved at 2-weeks and 2-months following real-tDCS but not sham. Despite individual variability with respect to optimal tDCS approach, certain montages result in consistent transient improvement in persons with chronic post-stroke aphasia. This preliminary study supports the notion that individualized tDCS treatment may enhance aphasia recovery in a persistent manner. PMID:25954178

Induction of cortical plasticity and improved motor performance following unilateral and bilateral transcranial direct current stimulation of the primary motor cortex.

PubMed

Kidgell, Dawson J; Goodwill, Alicia M; Frazer, Ashlyn K; Daly, Robin M

2013-07-01

Transcranial direct current stimulation (tDCS) is a non-invasive technique that modulates the excitability of neurons within the primary motor cortex (M1). Research shows that anodal-tDCS applied over the non-dominant M1 (i.e. unilateral stimulation) improves motor function of the non-dominant hand. Similarly, previous studies also show that applying cathodal tDCS over the dominant M1 improves motor function of the non-dominant hand, presumably by reducing interhemispheric inhibition. In the present study, one condition involved anodal-tDCS over the non-dominant M1 (unilateral stimulation) whilst a second condition involved applying cathodal-tDCS over the dominant M1 and anodal-tDCS over non-dominant M1 (bilateral stimulation) to determine if unilateral or bilateral stimulation differentially modulates motor function of the non-dominant hand. Using a randomized, cross-over design, 11 right-handed participants underwent three stimulation conditions: 1) unilateral stimulation, that involved anodal-tDCS applied over the non-dominant M1, 2) bilateral stimulation, whereby anodal-tDCS was applied over the non-dominant M1, and cathodal-tDCS over the dominant M1, and 3) sham stimulation. Transcranial magnetic stimulation (TMS) was performed before, immediately after, 30 and 60 minutes after stimulation to elucidate the neural mechanisms underlying any potential after-effects on motor performance. Motor function was evaluated by the Purdue pegboard test. There were significant improvements in motor function following unilateral and bilateral stimulation when compared to sham stimulation at all-time points (all P < 0.05); however there was no difference across time points between unilateral and bilateral stimulation. There was also a similar significant increase in corticomotor excitability with both unilateral and bilateral stimulation immediately post, 30 minutes and 60 minutes compared to sham stimulation (all P < 0.05). Unilateral and bilateral stimulation reduced short-interval intracortical inhibition (SICI) immediately post and at 30 minutes (all P < 0.05), but returned to baseline in both conditions at 60 minutes. There was no difference between unilateral and bilateral stimulation for SICI (P > 0.05). Furthermore, changes in corticomotor plasticity were not related to changes in motor performance. These results indicate that tDCS induced behavioural changes in the non-dominant hand as a consequence of mechanisms associated with use-dependant cortical plasticity that is independent of the electrode arrangement.

The treatment of Parkinson's disease with deep brain stimulation: current issues

PubMed Central

Moldovan, Alexia-Sabine; Groiss, Stefan Jun; Elben, Saskia; Südmeyer, Martin; Schnitzler, Alfons; Wojtecki, Lars

2015-01-01

Deep brain stimulation has become a well-established symptomatic treatment for Parkinson's disease during the last 25 years. Besides improving motor symptoms and long-term motor complications, positive effects on patients’ mobility, activities of daily living, emotional well-being and health-related quality of life have been recognized. Apart from that, numerous clinical trials analyzed effects on non-motor symptoms and side effects of deep brain stimulation. Several technical issues and stimulation paradigms have been and are still being developed to optimize the therapeutic effects, minimize the side effects and facilitate handling. This review summarizes current therapeutic issues, i.e., patient and target selection, surgical procedure and programming paradigms. In addition it focuses on neuropsychological effects and side effects of deep brain stimulation. PMID:26330809

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.

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.

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.

Current trends in stroke rehabilitation. A review with focus on brain plasticity.

PubMed

Johansson, B B

2011-03-01

Current understanding of brain plasticity has lead to new approaches in ischemic stroke rehabilitation. Stroke units that combine good medical and nursing care with task-oriented intense training in an environment that provides confidence, stimulation and motivation significantly improve outcome. Repetitive trans-cranial magnetic stimulation (rTMS), and trans-cranial direct current stimulation (tDCS) are applied in rehabilitation of motor function. The long-term effect, optimal way of stimulation and possibly efficacy in cognitive rehabilitation need evaluation. Methods based on multisensory integration of motor, cognitive, and perceptual processes including action observation, mental training, and virtual reality are being tested. Different approaches of intensive aphasia training are described. Recent data on intensive melodic intonation therapy indicate that even patients with very severe non-fluent aphasia can regain speech through homotopic white matter tract plasticity. Music therapy is applied in motor and cognitive rehabilitation. To avoid the confounding effect of spontaneous improvement, most trials are preformed ≥3 months post stroke. Randomized controlled trials starting earlier after strokes are needed. More attention should be given to stroke heterogeneity, cognitive rehabilitation, and social adjustment and to genetic differences, including the role of BDNF polymorphism in brain plasticity. © 2010 John Wiley & Sons A/S.

Effect of contacts configuration and location on selective stimulation of cuff electrode.

PubMed

Taghipour-Farshi, Hamed; Frounchi, Javad; Ahmadiasl, Nasser; Shahabi, Parviz; Salekzamani, Yaghoub

2015-01-01

Cuff electrodes have been widely used chronically in different clinical applications. Advancements have been made in selective stimulation by using multi-contact cuff electrodes. Steering anodic current is a strategy to increase selectivity by reshaping and localizing electric fields. There are two configurations for contacts to be implemented in cuff, monopolar and tripolar. A cuff electrode with tripolar configuration can restrict the activation to a more localized region within a nerve trunk compared to a cuff with monopolar configuration and improve the selectivity. Anode contacts in tripolar configuration can be made in two structures, "ring" and "dot". In this study, the stimulation capabilities of these two structures were evaluated. The recruitment properties and the selectivity of stimulation were examined by measuring the electric potential produced by stimulation currents. The results of the present study indicated that using dot configuration, the current needed to stimulate fascicles in tripolar topologies would be reduced by 10%. It was also shown that stimulation threshold was increased by moving anode contacts inward the cuff. On the other hand, stimulation threshold was decreased by moving the anode contacts outward the cuff which would decrease selectivity, too. We conclude that dot configuration is a better choice for stimulation. Also, a cuff inward placement of 10% relative to the cuff length was near optimal.

Effects of Low-frequency Current Sacral Dermatome Stimulation on Idiopathic Slow Transit Constipation

PubMed Central

Kim, Jin-Seop; Yi, Seung-Ju

2014-01-01

[Purpose] This study aimed to determine whether low-frequency current therapy can be used to reduce the symptoms of idiopathic slow transit constipation (ISTC). [Subjects] Fifteen patients (ten male and five female) with idiopathic slow transit constipation were enrolled in the present study. [Results] Bowel movements per day, bowel movements per week, and constipation assessment scale scores significantly improved after low-frequency current simulation of S2-S3. [Conclusion] Our results show that stimulation with low-frequency current of the sacral dermatomes may offer therapeutic benefits for a subject of patients with ISTC. PMID:25013277

Effects of Low-frequency Current Sacral Dermatome Stimulation on Idiopathic Slow Transit Constipation.

PubMed

Kim, Jin-Seop; Yi, Seung-Ju

2014-06-01

[Purpose] This study aimed to determine whether low-frequency current therapy can be used to reduce the symptoms of idiopathic slow transit constipation (ISTC). [Subjects] Fifteen patients (ten male and five female) with idiopathic slow transit constipation were enrolled in the present study. [Results] Bowel movements per day, bowel movements per week, and constipation assessment scale scores significantly improved after low-frequency current simulation of S2-S3. [Conclusion] Our results show that stimulation with low-frequency current of the sacral dermatomes may offer therapeutic benefits for a subject of patients with ISTC.

Reducing the Disruptive Effects of Interruptions With Noninvasive Brain Stimulation.

PubMed

Blumberg, Eric J; Foroughi, Cyrus K; Scheldrup, Melissa R; Peterson, Matthew S; Boehm-Davis, Debbie A; Parasuraman, Raja

2015-09-01

The authors determine whether transcranial direct current stimulation (tDCS) can reduce resumption time when an ongoing task is interrupted. Interruptions are common and disruptive. Working memory capacity has been shown to predict resumption lag (i.e., time to successfully resume a task after interruption). Given that tDCS applied to brain areas associated with working memory can enhance performance, tDCS has the potential to improve resumption lag when a task is interrupted. Participants were randomly assigned to one of four groups that received anodal (active) stimulation of 2 mA tDCS to one of two target brain regions, left and right dorsolateral prefrontal cortex (DLPFC), or to one of two control areas, active stimulation of the left primary motor cortex or sham stimulation of the right DLPFC, while completing a financial management task that was intermittently interrupted with math problem solving. Anodal stimulation to the right and left DLPFC significantly reduced resumption lags compared to the control conditions (sham and left motor cortex stimulation). Additionally, there was no speed-accuracy tradeoff (i.e., the improvement in resumption time was not accompanied by an increased error rate). Noninvasive brain stimulation can significantly decrease resumption lag (improve performance) after a task is interrupted. Noninvasive brain stimulation offers an easy-to-apply tool that can significantly improve interrupted task performance. © 2014, Human Factors and Ergonomics Society.

Low-power transcutaneous current stimulator for wearable applications.

PubMed

Karpul, David; Cohen, Gregory K; Gargiulo, Gaetano D; van Schaik, André; McIntyre, Sarah; Breen, Paul P

2017-10-03

Peripheral neuropathic desensitization associated with aging, diabetes, alcoholism and HIV/AIDS, affects tens of millions of people worldwide, and there is little or no treatment available to improve sensory function. Recent studies that apply imperceptible continuous vibration or electrical stimulation have shown promise in improving sensitivity in both diseased and healthy participants. This class of interventions only has an effect during application, necessitating the design of a wearable device for everyday use. We present a circuit that allows for a low-power, low-cost and small form factor implementation of a current stimulator for the continuous application of subthreshold currents. This circuit acts as a voltage-to-current converter and has been tested to drive + 1 to - 1 mA into a 60 k[Formula: see text] load from DC to 1 kHz. Driving a 60 k[Formula: see text] load with a 2 mA peak-to-peak 1 kHz sinusoid, the circuit draws less than 21 mA from a 9 V source. The minimum operating current of the circuit is less than 12 mA. Voltage compliance is ± 60 V with just 1.02 mA drawn by the high voltage current drive circuitry. The circuit was implemented as a compact 46 mm × 21 mm two-layer PCB highlighting its potential for use in a body-worn device. No design to the best of our knowledge presents comparably low quiescent power with such high voltage compliance. This makes the design uniquely appropriate for low-power transcutaneous current stimulation in wearable applications. Further development of driving and instrumentation circuitry is recommended.

Transcranial Direct Current Stimulation in Patients with Prolonged Disorders of Consciousness: Combined Behavioral and Event-Related Potential Evidence.

PubMed

Zhang, Ye; Song, Weiqun; Du, Jubao; Huo, Su; Shan, Guixiang; Li, Ran

2017-01-01

The electrophysiological evidence supporting the therapeutic efficacy of multiple transcranial direct current stimulation (tDCS) sessions on consciousness improvement in patients with prolonged disorders of consciousness (DOCs) has not been firmly established. To assess the effects of repeated tDCS in patients with prolonged DOCs by Coma Recovery Scale-Revised (CRS-R) score and event-related potential (ERP). Using a sham-controlled randomized double-blind design, 26 patients were randomly assigned to either a real [five vegetative state (VS) and eight minimally conscious state (MCS) patients] or sham (six VS and seven MCS patients) stimulation group. The patients in the real stimulation group underwent 20 anodal tDCS sessions of the left dorsolateral prefrontal cortex (DLPFC) over 10 consecutive working days. The CRS-R score and P300 amplitude and latency in a hierarchical cognitive assessment were recorded to evaluate the consciousness level before tDCS and immediately after the 20 sessions. The intra-group CRS-R analysis revealed a clinically significant improvement in the MCS patients in the real stimulation group. The inter-group CRS-R analysis showed a significant difference in CRS-R between VS and MCS patients at baseline in both the real and sham stimulation groups. The intra-group ERP analysis revealed a significant increase in P300 amplitude after tDCS in the MCS patients in the real stimulation group, but no significant differences in P300 latency. For the inter-group ERP analysis, we observed significant differences regarding the presence of P300 at baseline between the VS and MCS patients in both groups. The repeated anodal tDCS of the left DLPFC could produce clinically significant improvements in MCS patients. The observed tDCS-related consciousness improvements might be related to improvements in attention resource allocation (reflected by the P300 amplitude). The findings support the use of tDCS in clinical practice and ERP might serve as an efficient electrophysiological assessment tool in patients with DOCs.

Current directions in non-invasive low intensity electric brain stimulation for depressive disorder.

PubMed

Schutter, Dennis J L G; Sack, Alexander T

2014-01-01

Non-invasive stimulation of the human brain to improve depressive symptoms is increasingly finding its way in clinical settings as a viable form of somatic treatment. Following successful modulation of neural excitability with subsequent antidepressant effects, neural polarization by administrating weak direct currents to the scalp has gained renewed interest. A new wave of basic and clinical studies seems to underscore the potential therapeutic value of direct current stimulation in the treatment of depression. Issues concerning the lack of mechanistic insights into the workings of modifying brain function through neural polarization and how this process translates to its antidepressant properties calls for additional research. The range of its clinical applicability has yet to be established.

Brain Neuromodulation Techniques: A Review.

PubMed

Lewis, Philip M; Thomson, Richard H; Rosenfeld, Jeffrey V; Fitzgerald, Paul B

2016-08-01

The modulation of brain function via the application of weak direct current was first observed directly in the early 19th century. In the past 3 decades, transcranial magnetic stimulation and deep brain stimulation have undergone clinical translation, offering alternatives to pharmacological treatment of neurological and neuropsychiatric disorders. Further development of novel neuromodulation techniques employing ultrasound, micro-scale magnetic fields and optogenetics is being propelled by a rapidly improving understanding of the clinical and experimental applications of artificially stimulating or depressing brain activity in human health and disease. With the current rapid growth in neuromodulation technologies and applications, it is timely to review the genesis of the field and the current state of the art in this area. © The Author(s) 2016.

Laboratory septic tank performance response to electrolytic stimulation.

PubMed

Zaveri, Rahul M; Flora, Joseph R V

2002-11-01

This research investigated the effects of electrolytic stimulation on the performance of two laboratory-scale septic tanks. The tanks were fed a synthetic solution that included cellulose, peptone trypticase, beef extract, and urea. After a baseline period with no passed current, currents ranging from 100 to 500 mA were passed through the electrodes. The chemical oxygen demand (COD) removal efficiency from the tanks improved when a current was passed, with higher removal efficiencies observed at higher levels of passed current. Hydrolytic reactions resulted in ammonia and phosphate levels in the tanks that were higher than the influent. At currents > 300 mA, these hydrolytic reactions were suppressed, resulting in phosphate levels similar to the influent and ammonia levels lower than the influent because of the settling of ammonia-containing components of the feed solution. A slight increase in nitrate levels was observed when a current was passed, indicating minimal stimulation of nitrification activity. Abiotic studies confirmed that the COD can be removed via electrolysis and the removal was proportional to the passed current. Under the conditions of this study, the primary benefit of electrolytic stimulation of the septic tank is enhanced COD removal.

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.

Theory of feedback controlled brain stimulations for Parkinson's disease

NASA Astrophysics Data System (ADS)

Sanzeni, A.; Celani, A.; Tiana, G.; Vergassola, M.

2016-01-01

Limb tremor and other debilitating symptoms caused by the neurodegenerative Parkinson's disease are currently treated by administering drugs and by fixed-frequency deep brain stimulation. The latter interferes directly with the brain dynamics by delivering electrical impulses to neurons in the subthalamic nucleus. While deep brain stimulation has shown therapeutic benefits in many instances, its mechanism is still unclear. Since its understanding could lead to improved protocols of stimulation and feedback control, we have studied a mathematical model of the many-body neural network dynamics controlling the dynamics of the basal ganglia. On the basis of the results obtained from the model, we propose a new procedure of active stimulation, that depends on the feedback of the network and that respects the constraints imposed by existing technology. We show by numerical simulations that the new protocol outperforms the standard ones for deep brain stimulation and we suggest future experiments that could further improve the feedback procedure.

Efficacy of Selected Electrical Therapies on Chronic Low Back Pain: A Comparative Clinical Pilot Study.

PubMed

Rajfur, Joanna; Pasternok, Małgorzata; Rajfur, Katarzyna; Walewicz, Karolina; Fras, Beata; Bolach, Bartosz; Dymarek, Robert; Rosinczuk, Joanna; Halski, Tomasz; Taradaj, Jakub

2017-01-07

BACKGROUND In the currently available research publications on electrical therapy of low back pain, generally no control groups or detailed randomization were used, and such studies were often conducted with relatively small groups of patients, based solely on subjective questionnaires and pain assessment scales (lacking measurement methods to objectify the therapeutic progress). The available literature also lacks a comprehensive and large-scale clinical study. The purpose of this study was to assess the effects of treating low back pain using selected electrotherapy methods. The study assesses the influence of individual electrotherapeutic treatments on reduction of pain, improvement of the range of movement in lower section of the spine, and improvement of motor functions and mobility. MATERIAL AND METHODS The 127 patients qualified for the therapy (ultimately, 123 patients completed the study) and assigned to 6 comparison groups: A - conventional TENS, B - acupuncture-like TENS, C - high-voltage electrical stimulation, D - interferential current stimulation, E - diadynamic current, and F - control group. RESULTS The research showed that using electrical stimulation with interferential current penetrating deeper into the tissues results in a significant and more efficient elimination of pain, and an improvement of functional ability of patients suffering from low back pain on the basis of an analysis of both subjective and objective parameters. The TENS currents and high voltage were helpful, but not as effective. The use of diadynamic currents appears to be useless. CONCLUSIONS Selected electrical therapies (interferential current, TENS, and high voltage) appear to be effective in treating chronic low back pain.

Efficacy of Selected Electrical Therapies on Chronic Low Back Pain: A Comparative Clinical Pilot Study

PubMed Central

Rajfur, Joanna; Pasternok, Małgorzata; Rajfur, Katarzyna; Walewicz, Karolina; Fras, Beata; Bolach, Bartosz; Dymarek, Robert; Rosinczuk, Joanna; Halski, Tomasz; Taradaj, Jakub

2017-01-01

Background In the currently available research publications on electrical therapy of low back pain, generally no control groups or detailed randomization were used, and such studies were often conducted with relatively small groups of patients, based solely on subjective questionnaires and pain assessment scales (lacking measurement methods to objectify the therapeutic progress). The available literature also lacks a comprehensive and large-scale clinical study. The purpose of this study was to assess the effects of treating low back pain using selected electrotherapy methods. The study assesses the influence of individual electrotherapeutic treatments on reduction of pain, improvement of the range of movement in lower section of the spine, and improvement of motor functions and mobility. Material/Methods The 127 patients qualified for the therapy (ultimately, 123 patients completed the study) and assigned to 6 comparison groups: A – conventional TENS, B – acupuncture-like TENS, C – high-voltage electrical stimulation, D – interferential current stimulation, E – diadynamic current, and F – control group. Results The research showed that using electrical stimulation with interferential current penetrating deeper into the tissues results in a significant and more efficient elimination of pain, and an improvement of functional ability of patients suffering from low back pain on the basis of an analysis of both subjective and objective parameters. The TENS currents and high voltage were helpful, but not as effective. The use of diadynamic currents appears to be useless. Conclusions Selected electrical therapies (interferential current, TENS, and high voltage) appear to be effective in treating chronic low back pain. PMID:28062862

Treatment for Stimulant Use Disorders. Treatment Improvement Protocol (TIP) Series 33.

ERIC Educational Resources Information Center

Substance Abuse and Mental Health Services Administration (DHHS/PHS), Rockville, MD. Center for Substance Abuse Treatment.

This TIP on the best practice guidelines for treatment of substance abuse provides basic knowledge for practitioners, educators, and paraprofessionals about the nature and treatment of stimulant use disorders. More specifically, it reviews what is currently known about treating the medical, psychiatric, and substance abuse/dependence problems…

Interferential current sensory stimulation, through the neck skin, improves airway defense and oral nutrition intake in patients with dysphagia: a double-blind randomized controlled trial.

PubMed

Maeda, Keisuke; Koga, Takayuki; Akagi, Junji

2017-01-01

Neuromuscular electrical stimulation with muscle contraction, administered through the skin of the neck, improves a patient's swallowing ability. However, the beneficial effects of transcutaneous electrical sensory stimulation (TESS), without muscle contraction, are controversial. We investigated the effect of TESS, using interferential current, in patients undergoing dysphagia rehabilitation. This double-blind, randomized controlled trial involved 43 patients who were prescribed in-hospital dysphagia rehabilitation for ≥3 weeks. Patients were randomly assigned to the sensory stimulation (SS) or sham groups; all received usual rehabilitative care plus 2 weeks of SS or sham intervention. Outcome measures included cough latency times against a 1% citric acid mist, functional oral intake scale (FOIS) scores, and oral nutritional intake - each determined after the second and third week following treatment initiation. Mean patient age was 84.3±7.5 years; 58% were women. The SS and sham groups had similar baseline characteristics. Changes in cough latency time at 2 weeks (-14.1±14.0 vs -5.2±14.2 s, p =0.047) and oral nutrition intake at 3 weeks (437±575 vs 138±315 kcal/day, p =0.042) improved more in the SS group than in the sham group. Changes in cough frequency and FOIS scores indicated better outcomes in the SS group, based on substantial effect sizes. TESS, using interferential current through the neck, improved airway defense and nutrition in patients suffering from dysphagia. Further large-scale studies are needed to confirm the technique's effect on swallowing ability.

Controversy: Noninvasive and invasive cortical stimulation show efficacy in treating stroke patients.

PubMed

Hummel, Friedhelm C; Celnik, Pablo; Pascual-Leone, Alvero; Fregni, Felipe; Byblow, Winston D; Buetefisch, Cathrin M; Rothwell, John; Cohen, Leonardo G; Gerloff, Christian

2008-10-01

Stroke is the leading cause of disability in the adult population of western industrialized countries. Despite significant improvements of acute stroke care, two thirds of stroke survivors have to cope with persisting neurologic deficits. Adjuvant brain stimulation is a novel approach to improving the treatment of residual deficits after stroke. Transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and epidural electrical stimulation have been used in first trials on small cohorts of stroke patients. Effect sizes in the order of 8% to 30% of functional improvement have been reported, but a publication bias toward presenting "promising" but not negative results is likely. Many questions regarding underlying mechanisms, optimal stimulation parameters, combination with other types of interventions, among others, are open. This review addresses six controversies related to the experimental application of brain stimulation techniques to stroke patients. Cortical stimulation after stroke will need to be individually tailored and a thorough patient stratification according to type and extent of clinical deficit, lesion location, lesion size, comorbidities, time in the recovery process, and perhaps also age and gender will be necessary. There is consensus that cortical stimulation in stroke patients is still experimental and should only be applied in the frame of scientific studies.

StimDuino: an Arduino-based electrophysiological stimulus isolator.

PubMed

Sheinin, Anton; Lavi, Ayal; Michaelevski, Izhak

2015-03-30

Electrical stimulus isolator is a widely used device in electrophysiology. The timing of the stimulus application is usually automated and controlled by the external device or acquisition software; however, the intensity of the stimulus is adjusted manually. Inaccuracy, lack of reproducibility and no automation of the experimental protocol are disadvantages of the manual adjustment. To overcome these shortcomings, we developed StimDuino, an inexpensive Arduino-controlled stimulus isolator allowing highly accurate, reproducible automated setting of the stimulation current. The intensity of the stimulation current delivered by StimDuino is controlled by Arduino, an open-source microcontroller development platform. The automatic stimulation patterns are software-controlled and the parameters are set from Matlab-coded simple, intuitive and user-friendly graphical user interface. The software also allows remote control of the device over the network. Electrical current measurements showed that StimDuino produces the requested current output with high accuracy. In both hippocampal slice and in vivo recordings, the fEPSP measurements obtained with StimDuino and the commercial stimulus isolators showed high correlation. Commercial stimulus isolators are manually managed, while StimDuino generates automatic stimulation patterns with increasing current intensity. The pattern is utilized for the input-output relationship analysis, necessary for assessment of excitability. In contrast to StimuDuino, not all commercial devices are capable for remote control of the parameters and stimulation process. StimDuino-generated automation of the input-output relationship assessment eliminates need for the current intensity manually adjusting, improves stimulation reproducibility, accuracy and allows on-site and remote control of the stimulation parameters. Copyright © 2015 Elsevier B.V. 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.

The Use of Brain Stimulation in Dysphagia Management.

PubMed

Simons, Andre; Hamdy, Shaheen

2017-04-01

Dysphagia is common sequela of brain injury with as many as 50% of patients suffering from dysphagia following stroke. Currently, the majority of guidelines for clinical practice in the management of dysphagia focus on the prevention of complications while any natural recovery takes place. Recently, however, non-invasive brain stimulation (NIBS) techniques like transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have started to attract attention and are applied to investigate both the physiology of swallowing and influences on dysphagia. TMS allows for painless stimulation of the brain through an intact skull-an effect which would normally be impossible with electrical currents due to the high resistance of the skull. By comparison, tDCS involves passing a small electric current (usually under 2 mA) produced by a current generator over the scalp and cranium external to the brain. Initial studies used these techniques to better understand the physiological mechanisms of swallowing in healthy subjects. More recently, a number of studies have investigated the efficacy of these techniques in the management of neurogenic dysphagia with mixed results. Controversy still exists as to which site, strength and duration of stimulation yields the greatest improvement in dysphagia. And while multiple studies have suggested promising effects of NIBS, more randomised control trials with larger sample sizes are needed to investigate the short- and long-term effects of NIBS in neurogenic dysphagia.

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.

Memory improvement via slow-oscillatory stimulation during sleep in older adults.

PubMed

Westerberg, Carmen E; Florczak, Susan M; Weintraub, Sandra; Mesulam, M-Marsel; Marshall, Lisa; Zee, Phyllis C; Paller, Ken A

2015-09-01

We examined the intriguing but controversial idea that disrupted sleep-dependent consolidation contributes to age-related memory decline. Slow-wave activity during sleep may help strengthen neural connections and provide memories with long-term stability, in which case decreased slow-wave activity in older adults could contribute to their weaker memories. One prediction from this account is that age-related memory deficits should be reduced by artificially enhancing slow-wave activity. In young adults, applying transcranial current oscillating at a slow frequency (0.75 Hz) during sleep improves memory. Here, we tested whether this procedure can improve memory in older adults. In 2 sessions separated by 1 week, we applied either slow-oscillatory stimulation or sham stimulation during an afternoon nap in a double-blind, crossover design. Memory tests were administered before and after sleep. A larger improvement in word-pair recall and higher slow-wave activity was observed with slow-oscillatory stimulation than with sham stimulation. This is the first demonstration that this procedure can improve memory in older adults, suggesting that declarative memory performance in older adults is partly dependent on slow-wave activity during sleep. Copyright © 2015 Elsevier Inc. All rights reserved.

The Effect of Electrical Stimulation in Improving Muscle Tone (Clinical)

NASA Astrophysics Data System (ADS)

Azman, M. F.; Azman, A. W.

2017-11-01

Electrical stimulation (ES) and also known as neuromuscular electrical stimulation (NMES) and transcutaneous electrical stimulation (TES) involves the use of electrical current to stimulate the nerves or nerve endings that innervate muscle beneath the skin. Electrical stimulation may be applied superficially on the skin (transcutaneously) or directly into a muscle or muscles (intramuscularly) for the primary purpose of enhancing muscle function. The basic theoretical premise is that if the peripheral nerve can be stimulated, the resulting excitation impulse will be transmitted along the nerve to the motor endplates in the muscle, producing a muscle contraction. In this work, the effect of mere electrical stimulation to the muscle bulk and strength are tested. This paper explains how electrical stimulation can affect the muscle bulk, muscle size, muscle tone, muscle atrophy and muscle strength. The experiment and data collection are performed on 5 subjects and the results obtained are analyzed. This research aims to understand the full potential of electrical stimulation and identifying its possible benefits or disadvantages to the muscle properties. The results indicated that electrical stimulation alone able to improve muscle properties but with certain limits and precautions which might be useful in rehabilitation programme.

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.

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

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.

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.

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.

Did I Do That? Expectancy Effects of Brain Stimulation on Error-related Negativity and Sense of Agency.

PubMed

Hoogeveen, Suzanne; Schjoedt, Uffe; van Elk, Michiel

2018-06-19

This study examines the effects of expected transcranial stimulation on the error(-related) negativity (Ne or ERN) and the sense of agency in participants who perform a cognitive control task. Placebo transcranial direct current stimulation was used to elicit expectations of transcranially induced cognitive improvement or impairment. The improvement/impairment manipulation affected both the Ne/ERN and the sense of agency (i.e., whether participants attributed errors to oneself or the brain stimulation device): Expected improvement increased the ERN in response to errors compared with both impairment and control conditions. Expected impairment made participants falsely attribute errors to the transcranial stimulation. This decrease in sense of agency was correlated with a reduced ERN amplitude. These results show that expectations about transcranial stimulation impact users' neural response to self-generated errors and the attribution of responsibility-especially when actions lead to negative outcomes. We discuss our findings in relation to predictive processing theory according to which the effect of prior expectations on the ERN reflects the brain's attempt to generate predictive models of incoming information. By demonstrating that induced expectations about transcranial stimulation can have effects at a neural level, that is, beyond mere demand characteristics, our findings highlight the potential for placebo brain stimulation as a promising tool for research.

Anodal tDCS to V1 blocks visual perceptual learning consolidation.

PubMed

Peters, Megan A K; Thompson, Benjamin; Merabet, Lotfi B; Wu, Allan D; Shams, Ladan

2013-06-01

This study examined the effects of visual cortex transcranial direct current stimulation (tDCS) on visual processing and learning. Participants performed a contrast detection task on two consecutive days. Each session consisted of a baseline measurement followed by measurements made during active or sham stimulation. On the first day, one group received anodal stimulation to primary visual cortex (V1), while another received cathodal stimulation. Stimulation polarity was reversed for these groups on the second day. The third (control) group of subjects received sham stimulation on both days. No improvements or decrements in contrast sensitivity relative to the same-day baseline were observed during real tDCS, nor was any within-session learning trend observed. However, task performance improved significantly from Day 1 to Day 2 for the participants who received cathodal tDCS on Day 1 and for the sham group. No such improvement was found for the participants who received anodal stimulation on Day 1, indicating that anodal tDCS blocked overnight consolidation of visual learning, perhaps through engagement of inhibitory homeostatic plasticity mechanisms or alteration of the signal-to-noise ratio within stimulated cortex. These results show that applying tDCS to the visual cortex can modify consolidation of visual learning. Copyright © 2013 Elsevier Ltd. All rights reserved.

Unilateral prefrontal direct current stimulation effects are modulated by working memory load and gender.

PubMed

Meiron, Oded; Lavidor, Michal

2013-05-01

Recent studies revealed that anodal transcranial direct current stimulation (tDCS) to the left dorsolateral prefrontal cortex (DLPFC) may improve verbal working memory (WM) performance in humans. In the present study, we evaluated executive attention, which is the core of WM capacity, considered to be significantly involved in tasks that require active maintenance of memory representations in interference-rich conditions, and is highly dependent on DLPFC function. We investigated verbal WM accuracy using a WM task that is highly sensitive to executive attention function. We were interested in how verbal WM accuracy may be affected by WM load, unilateral DLPFC stimulation, and gender, as previous studies showed gender-dependent brain activation during verbal WM tasks. We utilized a modified verbal n-Back task hypothesized to increase demands on executive attention. We examined "online" WM performance while participants received transcranial direct current stimulation (tDCS), and implicit learning performance in a post-stimulation WM task. Significant lateralized "online" stimulation effects were found only in the highest WM load condition revealing that males benefit from left DLPFC stimulation, while females benefit from right DLPFC stimulation. High WM load performance in the left DLPFC stimulation was significantly related to post-stimulation recall performance. Our findings support the idea that lateralized stimulation effects in high verbal WM load may be gender-dependent. Further, our post-stimulation results support the idea that increased left hemisphere activity may be important for encoding verbal information into episodic memory as well as for facilitating retrieval of context-specific targets from semantic memory. Copyright © 2013 Elsevier Inc. All rights reserved.

Assessment of anodal and cathodal transcranial direct current stimulation (tDCS) on MMN-indexed auditory sensory processing.

PubMed

Impey, Danielle; de la Salle, Sara; Knott, Verner

2016-06-01

Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which uses a very weak constant current to temporarily excite (anodal stimulation) or inhibit (cathodal stimulation) activity in the brain area of interest via small electrodes placed on the scalp. Currently, tDCS of the frontal cortex is being used as a tool to investigate cognition in healthy controls and to improve symptoms in neurological and psychiatric patients. tDCS has been found to facilitate cognitive performance on measures of attention, memory, and frontal-executive functions. Recently, a short session of anodal tDCS over the temporal lobe has been shown to increase auditory sensory processing as indexed by the Mismatch Negativity (MMN) event-related potential (ERP). This preliminary pilot study examined the separate and interacting effects of both anodal and cathodal tDCS on MMN-indexed auditory pitch discrimination. In a randomized, double blind design, the MMN was assessed before (baseline) and after tDCS (2mA, 20min) in 2 separate sessions, one involving 'sham' stimulation (the device is turned off), followed by anodal stimulation (to temporarily excite cortical activity locally), and one involving cathodal stimulation (to temporarily decrease cortical activity locally), followed by anodal stimulation. Results demonstrated that anodal tDCS over the temporal cortex increased MMN-indexed auditory detection of pitch deviance, and while cathodal tDCS decreased auditory discrimination in baseline-stratified groups, subsequent anodal stimulation did not significantly alter MMN amplitudes. These findings strengthen the position that tDCS effects on cognition extend to the neural processing of sensory input and raise the possibility that this neuromodulatory technique may be useful for investigating sensory processing deficits in clinical populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Parents report on stimulant-treated children in the Netherlands: initiation of treatment and follow-up care.

PubMed

Faber, Adrianne; Kalverdijk, Luuk J; de Jong-van den Berg, Lolkje T W; Hugtenburg, Jacqueline G; Minderaa, Ruud B; Tobi, Hilde

2006-08-01

The aim of this study was to describe current practices around initiation and follow-up care of stimulant treatment among stimulant-treated children in a nationwide survey among parents. A total of 115 pharmacies detected current stimulant users <16 years old in their pharmacy information system and sent parents a questionnaire regarding their child's stimulant treatment. Parents returned 924 of 1,307 questionnaires (71%). The median age of the stimulant users was 10 years and 85% were boys. In all, 91% were diagnosed with attention-deficit/hyperactivity disorder (ADHD). In 77% of the cases, the child or parents received other therapies besides stimulants-21% received psychotropic co-medication, with melatonin (11%) and antipsychotics (7%) being mentioned most frequently. Stimulant use was primarily initiated by child psychiatrists (51%) and pediatricians (32%), but most children received repeat prescriptions from general practitioners (61%). Of these 924 children, 19% did not receive any follow-up care, and transfer of prescribing responsibility increased the risk of not receiving follow-up care. The 732 children (79%) who were monitored visited a physician approximately twice a year. During follow-up visits, pediatricians performed physical check ups significantly more often. Stimulant treatment in The Netherlands is initiated mainly by specialists such as child psychiatrists and pediatricians. In the current study, follow-up care for stimulant-treated children in The Netherlands appeared to be poor, suggesting an urgent need for improvement.

Balanced bifrontal transcranial direct current stimulation enhances working memory in adults with high-functioning autism: a sham-controlled crossover study.

PubMed

van Steenburgh, J Jason; Varvaris, Mark; Schretlen, David J; Vannorsdall, Tracy D; Gordon, Barry

2017-01-01

Working memory (WM) often is impaired in autism spectrum disorder (ASD). Such impairment may underlie core deficits in cognition and social functioning. Transcranial direct current stimulation (tDCS) has been shown to enhance WM in both healthy adults and clinical populations, but its efficacy in ASD is unknown. We predicted that bifrontal tDCS would improve WM performances of adults with high-functioning autism during active stimulation compared to sham stimulation and that such enhancement would generalize to an untrained task. Twelve adults with high-functioning ASD engaged in a battery of WM tasks that included backward spatial span, backward digit span, spatial n -back and letter n -back. While engaged, 40 min of 1.5 mA bifrontal stimulation was applied over the left and the right dorsolateral prefrontal cortices (DLPFC). Using a single-blind crossover design, each participant received left anodal/right cathodal stimulation, right anodal/left cathodal stimulation, or sham stimulation, in randomized counterbalanced order on three separate days. Following tDCS, participants again engaged in letter and spatial n -back tasks before taking the Brief Test of Attention (BTA). We used repeated-measures ANOVA to compare overall performance on the WM battery as measured by a composite of z -scores for all five measures. Post hoc ANOVAs, t tests, Friedman's tests, and Wilcoxon signed-rank tests were used to measure the online and offline effects of tDCS and to assess performances on individual measures. Compared to sham stimulation, both left DLPFC anodal stimulation ( t 11  = 5.4, p  = 0.0002) and right DLPFC anodal stimulation ( t 11  = 3.57, p  = 0.004) improved overall WM performance. Left anodal stimulation ( t 11  = 3.9, p  = 0.003) and right anodal stimulation ( t 11  = 2.7, p  = 0.019) enhanced performances during stimulation. Enhancement transferred to an untrained task 50 min after right anodal stimulation (z 11  = 2.263, p  = 0.024). The tasks that showed the largest effects of active stimulation were spatial span backward ( z 11  = 2.39, p  = 0.017) and BTA ( z 11  = 2.263, p  = 0.024). In adults with high-functioning ASD, active bifrontal tDCS given during WM tasks appears to improve performance. TDCS benefits also transferred to an untrained task completed shortly after stimulation. These results suggest that tDCS can improve WM task performance and could reduce some core deficits of autism. NCT01602263.

Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

PubMed Central

Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C

2017-01-01

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials. DOI: http://dx.doi.org/10.7554/eLife.18834.001 PMID:28169833

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.

Application of constant current, low voltage electrical stimulation systems to pig carcasses and its effects on pork quality.

PubMed

Channon, H A; Walker, P J; Kerr, M G; Baud, S R

2003-12-01

This study examined the effectiveness of a constant current, low voltage electrical stimulation system on improving pork quality when applied to pigs at 2 min post-exsanguination. A total of 48 female Duroc×Large White/Landrace pigs of 85-90 kg liveweight were randomly allocated immediately prior to slaughter to one of four constant current electrical stimulation treatments: control (no electrical stimulation), 50, 200 and 400 mA. Stimulation was applied to pig carcasses at 2 min post-exsanguination for 30 s. No differences (P>0.05) in WB shear force values, muscle lightness or PSE incidence of pork M. longissimus lumborum (LL) was found due to electrical stimulation treatment. Muscle pH of the LL muscle was lower (P<0.001) in carcasses in the 200 and 400 mA treatments compared to those from carcasses in both the 50 mA and control treatment groups, when measured at the various time points from 40 min to 8 h post-slaughter. Although carcasses stimulated with 200 and 400 mA had higher percentage drip loss (P<0.05) and purge (P<0.001), this was not found to impact WB shear force values, muscle lightness or PSE incidence.

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 Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Transcranial Direct Current Stimulation of the Temporoparietal Junction and Inferior Frontal Cortex Improves Imitation-Inhibition and Perspective-Taking with no Effect on the Autism-Spectrum Quotient Score.

PubMed

Nobusako, Satoshi; Nishi, Yuki; Nishi, Yuki; Shuto, Takashi; Asano, Daiki; Osumi, Michihiro; Morioka, Shu

2017-01-01

Lesions to brain regions such as the temporoparietal junction (TPJ) and inferior frontal cortex (IFC) are thought to cause autism-spectrum disorder (ASD). Previous studies indicated that transcranial direct current stimulation (tDCS) of the right TPJ improves social cognitive functions such as imitation-inhibition and perspective-taking. Although previous work shows that tDCS of the right IFC improves imitation-inhibition, its effects on perspective-taking have yet to be determined. In addition, the role of the TPJ and IFC in determining the Autism-Spectrum Quotient (AQ), which is a measure of autism spectrum traits, is still unclear. Thus, the current study performed tDCS on the right TPJ and the right IFC of healthy adults, and examined its effects on imitation-inhibition, perspective-taking and AQ scores. Based on previous studies, we hypothesized that anodal tDCS of the right IFC and right TPJ would improve imitation-inhibition, perspective-taking and the AQ score. Anodal tDCS of the right TPJ or IFC significantly decreased the interference effect in an imitation-inhibition task and the cost of perspective-taking in a perspective-taking task, in comparison to the sham stimulation control. These findings indicated that both the TPJ and the IFC play a role in imitation-inhibition and perspective-taking, i.e., control of self and other representations. However, anodal stimulation of the right TPJ and the right IFC did not alter participants' AQ. This finding conflicts with results from previous brain imaging studies, which could be attributed to methodological differences such as variation in sex, age and ASD. Therefore, further research is necessary to determine the relationship between the TPJ and IFC, and the AQ.

Transcranial Direct Current Stimulation of the Temporoparietal Junction and Inferior Frontal Cortex Improves Imitation-Inhibition and Perspective-Taking with no Effect on the Autism-Spectrum Quotient Score

PubMed Central

Nobusako, Satoshi; Nishi, Yuki; Nishi, Yuki; Shuto, Takashi; Asano, Daiki; Osumi, Michihiro; Morioka, Shu

2017-01-01

Lesions to brain regions such as the temporoparietal junction (TPJ) and inferior frontal cortex (IFC) are thought to cause autism-spectrum disorder (ASD). Previous studies indicated that transcranial direct current stimulation (tDCS) of the right TPJ improves social cognitive functions such as imitation-inhibition and perspective-taking. Although previous work shows that tDCS of the right IFC improves imitation-inhibition, its effects on perspective-taking have yet to be determined. In addition, the role of the TPJ and IFC in determining the Autism-Spectrum Quotient (AQ), which is a measure of autism spectrum traits, is still unclear. Thus, the current study performed tDCS on the right TPJ and the right IFC of healthy adults, and examined its effects on imitation-inhibition, perspective-taking and AQ scores. Based on previous studies, we hypothesized that anodal tDCS of the right IFC and right TPJ would improve imitation-inhibition, perspective-taking and the AQ score. Anodal tDCS of the right TPJ or IFC significantly decreased the interference effect in an imitation-inhibition task and the cost of perspective-taking in a perspective-taking task, in comparison to the sham stimulation control. These findings indicated that both the TPJ and the IFC play a role in imitation-inhibition and perspective-taking, i.e., control of self and other representations. However, anodal stimulation of the right TPJ and the right IFC did not alter participants’ AQ. This finding conflicts with results from previous brain imaging studies, which could be attributed to methodological differences such as variation in sex, age and ASD. Therefore, further research is necessary to determine the relationship between the TPJ and IFC, and the AQ. PMID:28536512

Interferential current sensory stimulation, through the neck skin, improves airway defense and oral nutrition intake in patients with dysphagia: a double-blind randomized controlled trial

PubMed Central

Maeda, Keisuke; Koga, Takayuki; Akagi, Junji

2017-01-01

Background Neuromuscular electrical stimulation with muscle contraction, administered through the skin of the neck, improves a patient’s swallowing ability. However, the beneficial effects of transcutaneous electrical sensory stimulation (TESS), without muscle contraction, are controversial. We investigated the effect of TESS, using interferential current, in patients undergoing dysphagia rehabilitation. Methods This double-blind, randomized controlled trial involved 43 patients who were prescribed in-hospital dysphagia rehabilitation for ≥3 weeks. Patients were randomly assigned to the sensory stimulation (SS) or sham groups; all received usual rehabilitative care plus 2 weeks of SS or sham intervention. Outcome measures included cough latency times against a 1% citric acid mist, functional oral intake scale (FOIS) scores, and oral nutritional intake – each determined after the second and third week following treatment initiation. Results Mean patient age was 84.3±7.5 years; 58% were women. The SS and sham groups had similar baseline characteristics. Changes in cough latency time at 2 weeks (−14.1±14.0 vs −5.2±14.2 s, p=0.047) and oral nutrition intake at 3 weeks (437±575 vs 138±315 kcal/day, p=0.042) improved more in the SS group than in the sham group. Changes in cough frequency and FOIS scores indicated better outcomes in the SS group, based on substantial effect sizes. Conclusion TESS, using interferential current through the neck, improved airway defense and nutrition in patients suffering from dysphagia. Further large-scale studies are needed to confirm the technique’s effect on swallowing ability. PMID:29158670

Safe Direct Current Stimulator design for reduced power consumption and increased reliability.

PubMed

Fridman, Gene

2017-07-01

Current state of the art neural prosthetics, such as cochlear implants, spinal cord stimulators, and deep brain stimulators use implantable pulse generators (IPGs) to excite neural activity. Inhibition of neural firing is typically indirect and requires excitation of neurons that then have inhibitory projections downstream. Safe Direct Current Stimulator (SDCS) technology is designed to convert electronic pulses delivered to electrodes embedded within an implantable device to ionic direct current (iDC) at the output of the device. iDC from the device can then control neural extracellular potential with the intent of being able to not only excite, but also inhibit and sensitize neurons, thereby greatly expanding the possible applications of neuromodulation therapies and neural interface mechanisms. While the potential applications and proof of concept of this device have been the focus of previous work, the published descriptions of this technology leave significant room for power and reliability optimization. We describe and model a novel device construction designed to reduce power consumption by a factor of 12 and to improve its reliability by a factor of 8.

Current Topics in Epilepsy Surgery.

PubMed

Usui, Naotaka

2016-05-15

This article reviews the current topics in the field of epilepsy surgery. Each type of epilepsy is associated with a different set of questions and goals. In mesial temporal lobe epilepsy (MTLE) with hippocampal sclerosis (HS), postoperative seizure outcome is satisfactory. A recent meta-analysis revealed superior seizure outcome after anterior temporal lobectomy compared with selective amygdalohippocampectomy; in terms of cognitive outcome; however, amygdalohippocampectomy may be beneficial. In temporal lobe epilepsy with normal magnetic resonance imaging (MRI), postoperative seizure outcome is not as favorable as it is in MTLE with HS; further improvement of seizure outcome in these cases is necessary. Focal cortical dysplasia is the most common substrate in intractable neocortical epilepsy, especially in children, as well as in MRI-invisible neocortical epilepsy. Postoperative seizure-free outcome is approximately 60-70%; further diagnostic and therapeutic improvement is required. Regarding diagnostic methodology, an important topic currently under discussion is wideband electroencephalogram (EEG) analysis. Although high-frequency oscillations and ictal direct current shifts are considered important markers of epileptogenic zones, the clinical significance of these findings should be clarified further. Regarding alternatives to surgery, neuromodulation therapy can be an option for patients who are not amenable to resective surgery. In addition to vagus nerve stimulation, intracranial stimulation such as responsive neurostimulation or anterior thalamic stimulation is reported to have a modest seizure suppression effect. Postoperative management such as rehabilitation and antiepileptic drug (AED) management is important. It has been reported that postoperative rehabilitation improves postoperative employment status. Pre- and post-operative comprehensive care is mandatory for postoperative improvement of quality of life.

Transcutaneous electrical nerve stimulation and interferential current demonstrate similar effects in relieving acute and chronic pain: a systematic review with meta-analysis.

PubMed

Almeida, Camila Cadena de; Silva, Vinicius Z Maldaner da; Júnior, Gerson Cipriano; Liebano, Richard Eloin; Durigan, Joao Luiz Quagliotti

2018-02-02

Transcutaneous electrical nerve stimulation and interferential current have been widely used in clinical practice. However, a systematic review comparing their effects on pain relief has not yet been performed. To investigate the effects of transcutaneous electrical nerve stimulation and interferential current on acute and chronic pain. We use Pubmed, Embase, LILACS, PEDro and Cochrane Central Register of Controlled Trials as data sources. Two independent reviewers that selected studies according to inclusion criteria, extracted information of interest and verified the methodological quality of the studies made study selection. The studies were selected if transcutaneous electrical nerve stimulation and interferential current were used as treatment and they had pain as the main outcome, as evaluated by a visual analog scale. Secondary outcomes were the Western Ontario Macmaster and Rolland Morris Disability questionnaires, which were added after data extraction. Eight studies with a pooled sample of 825 patients were included. The methodological quality of the selected studies was moderate, with an average of six on a 0-10 scale (PEDro). In general, both transcutaneous electrical nerve stimulation and interferential current improved pain and functional outcomes without a statistical difference between them. Transcutaneous electrical nerve stimulation and interferential current have similar effects on pain outcome The low number of studies included in this meta-analysis indicates that new clinical trials are needed. Copyright © 2018 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Technical aspects of neurostimulation: Focus on equipment, electric field modeling, and stimulation protocols.

PubMed

Klooster, D C W; de Louw, A J A; Aldenkamp, A P; Besseling, R M H; Mestrom, R M C; Carrette, S; Zinger, S; Bergmans, J W M; Mess, W H; Vonck, K; Carrette, E; Breuer, L E M; Bernas, A; Tijhuis, A G; Boon, P

2016-06-01

Neuromodulation is a field of science, medicine, and bioengineering that encompasses implantable and non-implantable technologies for the purpose of improving quality of life and functioning of humans. Brain neuromodulation involves different neurostimulation techniques: transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS), which are being used both to study their effects on cognitive brain functions and to treat neuropsychiatric disorders. The mechanisms of action of neurostimulation remain incompletely understood. Insight into the technical basis of neurostimulation might be a first step towards a more profound understanding of these mechanisms, which might lead to improved clinical outcome and therapeutic potential. This review provides an overview of the technical basis of neurostimulation focusing on the equipment, the present understanding of induced electric fields, and the stimulation protocols. The review is written from a technical perspective aimed at supporting the use of neurostimulation in clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Optimization of return electrodes in neurostimulating arrays

NASA Astrophysics Data System (ADS)

Flores, Thomas; Goetz, Georges; Lei, Xin; Palanker, Daniel

2016-06-01

Objective. High resolution visual prostheses require dense stimulating arrays with localized inputs of individual electrodes. We study the electric field produced by multielectrode arrays in electrolyte to determine an optimal configuration of return electrodes and activation sequence. Approach. To determine the boundary conditions for computation of the electric field in electrolyte, we assessed current dynamics using an equivalent circuit of a multielectrode array with interleaved return electrodes. The electric field modeled with two different boundary conditions derived from the equivalent circuit was then compared to measurements of electric potential in electrolyte. To assess the effect of return electrode configuration on retinal stimulation, we transformed the computed electric fields into retinal response using a model of neural network-mediated stimulation. Main results. Electric currents at the capacitive electrode-electrolyte interface redistribute over time, so that boundary conditions transition from equipotential surfaces at the beginning of the pulse to uniform current density in steady state. Experimental measurements confirmed that, in steady state, the boundary condition corresponds to a uniform current density on electrode surfaces. Arrays with local return electrodes exhibit improved field confinement and can elicit stronger network-mediated retinal response compared to those with a common remote return. Connecting local return electrodes enhances the field penetration depth and allows reducing the return electrode area. Sequential activation of the pixels in large monopolar arrays reduces electrical cross-talk and improves the contrast in pattern stimulation. Significance. Accurate modeling of multielectrode arrays helps optimize the electrode configuration to maximize the spatial resolution, contrast and dynamic range of retinal prostheses.

Design of electrical stimulation bioreactors for cardiac tissue engineering.

PubMed

Tandon, N; Marsano, A; Cannizzaro, C; Voldman, J; Vunjak-Novakovic, G

2008-01-01

Electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. Carbon electrodes were found in past studies to have the best current injection characteristics. The goal of this study was to develop rational experimental design principles for the electrodes and stimulation regime, in particular electrode configuration, electrode ageing, and stimulation amplitude. Carbon rod electrodes were compared via electrochemical impedance spectroscopy (EIS) and we identified a safety range of 0 to 8 V/cm by comparing excitation thresholds and maximum capture rates for neonatal rat cardiomyocytes cultured with electrical stimulation. We conclude with recommendations for studies involving carbon electrodes for cardiac tissue engineering.

Stimulating Creativity: Modulation of Convergent and Divergent Thinking by Transcranial Direct Current Stimulation (tDCS)

ERIC Educational Resources Information Center

Zmigrod, Sharon; Colzato, Lorenza S.; Hommel, Bernhard

2015-01-01

Creativity has been conceptualized as involving 2 distinct components; divergent thinking, the search for multiple solutions to a single problem, and convergent thinking, the quest for a single solution either through an analytical process or the experience of insight. Studies have demonstrated that these abilities can be improved by cognitive…

Intraoperative acceleration measurements to quantify improvement in tremor during deep brain stimulation surgery.

PubMed

Shah, Ashesh; Coste, Jérôme; Lemaire, Jean-Jacques; Taub, Ethan; Schüpbach, W M Michael; Pollo, Claudio; Schkommodau, Erik; Guzman, Raphael; Hemm-Ode, Simone

2017-05-01

Deep brain stimulation (DBS) surgery is extensively used in the treatment of movement disorders. Nevertheless, methods to evaluate the clinical response during intraoperative stimulation tests to identify the optimal position for the implantation of the chronic DBS lead remain subjective. In this paper, we describe a new, versatile method for quantitative intraoperative evaluation of improvement in tremor with an acceleration sensor that is mounted on the patient's wrist during surgery. At each anatomical test position, the improvement in tremor compared to the initial tremor is estimated on the basis of extracted outcome measures. This method was tested on 15 tremor patients undergoing DBS surgery in two centers. Data from 359 stimulation tests were acquired. Our results suggest that accelerometric evaluation detects tremor changes more sensitively than subjective visual ratings. The effective stimulation current amplitudes identified from the quantitative data (1.1 ± 0.8 mA) are lower than those identified by visual evaluation (1.7 ± 0.8 mA) for similar improvement in tremor. Additionally, if these data had been used to choose the chronic implant position of the DBS lead, 15 of the 26 choices would have been different. These results show that our method of accelerometric evaluation can potentially improve DBS targeting.

Retinal stimulation strategies to restore vision: Fundamentals and systems.

PubMed

Yue, Lan; Weiland, James D; Roska, Botond; Humayun, Mark S

2016-07-01

Retinal degeneration, a leading cause of blindness worldwide, is primarily characterized by the dysfunctional/degenerated photoreceptors that impair the ability of the retina to detect light. Our group and others have shown that bioelectronic retinal implants restore useful visual input to those who have been blind for decades. This unprecedented approach of restoring sight demonstrates that patients can adapt to new visual input, and thereby opens up opportunities to not only improve this technology but also develop alternative retinal stimulation approaches. These future improvements or new technologies could have the potential of selectively stimulating specific cell classes in the inner retina, leading to improved visual resolution and color vision. In this review we will detail the progress of bioelectronic retinal implants and future devices in this genre as well as discuss other technologies such as optogenetics, chemical photoswitches, and ultrasound stimulation. We will discuss the principles, biological aspects, technology development, current status, clinical outcomes/prospects, and challenges for each approach. The review will cover functional imaging documented cortical responses to retinal stimulation in blind patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Design and development of a low-cost biphasic charge-balanced functional electric stimulator and its clinical validation.

PubMed

Shendkar, Chandrashekhar; Lenka, Prasanna K; Biswas, Abhishek; Kumar, Ratnesh; Mahadevappa, Manjunatha

2015-10-01

Functional electric stimulators that produce near-ideal, charge-balanced biphasic stimulation waveforms with interphase delay are considered safer and more efficacious than conventional stimulators. An indigenously designed, low-cost, portable FES device named InStim is developed. It features a charge-balanced biphasic single channel. The authors present the complete design, mathematical analysis of the circuit and the clinical evaluation of the device. The developed circuit was tested on stroke patients affected by foot drop problems. It was tested both under laboratory conditions and in clinical settings. The key building blocks of this circuit are low dropout regulators, a DC-DC voltage booster and a single high-power current source OP-Amp with current-limiting capabilities. This allows the device to deliver high-voltage, constant current, biphasic pulses without the use of a bulky step-up transformer. The advantages of the proposed design over the currently existing devices include improved safety features (zero DC current, current-limiting mechanism and safe pulses), waveform morphology that causes less muscle fatigue, cost-effectiveness and compact power-efficient circuit design with minimal components. The device is also capable of producing appropriate ankle dorsiflexion in patients having foot drop problems of various Medical Research Council scale grades.

Mineback Stimulation Research Experiments

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

Warpinski, N.R.

The objective of the Mineback Stimulation Research Experiments is to improve hydraulic fracture stimulation technology by providing an in situ laboratory where basic processes and mechanisms that control and influence fracture propagation can be observed, measured and understood. While previous tests have been instrumental in providing an understanding of the mechanisms controlling fracture height, current experiments are focused on fluid flow through the created fracture and the associated pressure drops and crack widths. Work performed, accomplishments and future plans are presented. 7 refs., 2 figs.

Transcranial direct current stimulation (tDCS) for improving capacity in activities and arm function after stroke: a network meta-analysis of randomised controlled trials.

PubMed

Elsner, Bernhard; Kwakkel, Gert; Kugler, Joachim; Mehrholz, Jan

2017-09-13

Transcranial Direct Current Stimulation (tDCS) is an emerging approach for improving capacity in activities of daily living (ADL) and upper limb function after stroke. However, it remains unclear what type of tDCS stimulation is most effective. Our aim was to give an overview of the evidence network regarding the efficacy and safety of tDCS and to estimate the effectiveness of the different stimulation types. We performed a systematic review of randomised trials using network meta-analysis (NMA), searching the following databases until 5 July 2016: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, AMED, Web of Science, and four other databases. We included studies with adult people with stroke. We compared any kind of active tDCS (anodal, cathodal, or dual, that is applying anodal and cathodal tDCS concurrently) regarding improvement of our primary outcome of ADL capacity, versus control, after stroke. CRD42016042055. We included 26 studies with 754 participants. Our NMA showed evidence of an effect of cathodal tDCS in improving our primary outcome, that of ADL capacity (standardized mean difference, SMD = 0.42; 95% CI 0.14 to 0.70). tDCS did not improve our secondary outcome, that of arm function, measured by the Fugl-Meyer upper extremity assessment (FM-UE). There was no difference in safety between tDCS and its control interventions, measured by the number of dropouts and adverse events. Comparing different forms of tDCS shows that cathodal tDCS is the most promising treatment option to improve ADL capacity in people with stroke.

Direct current stimulation over the anterior temporal areas boosts semantic processing in primary progressive aphasia.

PubMed

Teichmann, Marc; Lesoil, Constance; Godard, Juliette; Vernet, Marine; Bertrand, Anne; Levy, Richard; Dubois, Bruno; Lemoine, Laurie; Truong, Dennis Q; Bikson, Marom; Kas, Aurélie; Valero-Cabré, Antoni

2016-11-01

Noninvasive brain stimulation in primary progressive aphasia (PPA) is a promising approach. Yet, applied to single cases or insufficiently controlled small-cohort studies, it has not clarified its therapeutic value. We here address the effectiveness of transcranial direct current stimulation (tDCS) on the semantic PPA variant (sv-PPA), applying a rigorous study design to a large, homogeneous sv-PPA cohort. Using a double-blind, sham-controlled counterbalanced cross-over design, we applied three tDCS conditions targeting the temporal poles of 12 sv-PPA patients. Efficiency was assessed by a semantic matching task orthogonally manipulating "living"/"nonliving" categories and verbal/visual modalities. Conforming to predominantly left-lateralized damage in sv-PPA and accounts of interhemispheric inhibition, we applied left hemisphere anodal-excitatory and right hemisphere cathodal-inhibitory tDCS, compared to sham stimulation. Prestimulation data, compared to 15 healthy controls, showed that patients had semantic disorders predominating with living categories in the verbal modality. Stimulation selectively impacted these most impaired domains: Left-excitatory and right-inhibitory tDCS improved semantic accuracy in verbal modality, and right-inhibitory tDCS improved processing speed with living categories and accuracy and processing speed in the combined verbal × living condition. Our findings demonstrate the efficiency of tDCS in sv-PPA by generating highly specific intrasemantic effects. They provide "proof of concept" for future applications of tDCS in therapeutic multiday regimes, potentially driving sustained improvement of semantic processing. Our data also support the hotly debated existence of a left temporal-pole network for verbal semantics selectively modulated through both left-excitatory and right-inhibitory brain stimulation. Ann Neurol 2016;80:693-707. © 2016 American Neurological Association.

State of the Art: Novel Applications for Cortical Stimulation.

PubMed

De Ridder, Dirk; Perera, Sanjaya; Vanneste, Sven

2017-04-01

Electrical stimulation via implanted electrodes that overlie the cortex of the brain is an upcoming neurosurgical technique that was hindered for a long time by insufficient knowledge of how the brain functions in a dynamic, physiological, and pathological way, as well as by technological limitations of the implantable stimulation devices. This paper provides an overview of cortex stimulation via implantable devices and introduces future possibilities to improve cortex stimulation. Cortex stimulation was initially used preoperatively as a technique to localize functions in the brain and only later evolved into a treatment technique. It was first used for pain, but more recently a multitude of pathologies are being targeted by cortex stimulation. These disorders are being treated by stimulating different cortical areas of the brain. Risks and complications are essentially similar to those related to deep brain stimulation and predominantly include haemorrhage, seizures, infection, and hardware failures. For cortex stimulation to fully mature, further technological development is required to predict its outcomes and improve stimulation designs. This includes the development of network science-based functional connectivity approaches, genetic analyses, development of navigated high definition transcranial alternating current stimulation, and development of pseudorandom stimulation designs for preventing habituation. In conclusion, cortex stimulation is a nascent but very promising approach to treating a variety of diseases, but requires further technological development for predicting outcomes, such as network science based functional connectivity approaches, genetic analyses, development of navigated transcranial electrical stimulation, and development of pseudorandom stimulation designs for preventing habituation. © 2017 International Neuromodulation Society.

The effects of Transcranial Direct Current Stimulation (tDCS) on Idiopathic Hypersomnia: a pilot study.

PubMed

Galbiati, Andrea; Abutalebi, Jubin; Iannaccone, Sandro; Borsa, Virginia Maria; Musteata, Stela; Zucconi, Marco; Giora, Enrico; Ferini-Strambi, Luigi

2016-04-01

Idiopathic Hypersomnia (IH) is a rare sleep disorder characterised by excessive daytime sleepiness (EDS) that leads to invalidating daytime consequences. Till now the treatment of IH has mirrored that of sleepiness in narcolepsy, and it is mainly focused on symptoms' management. We employed an anodal transcranic Direct Current Stimulation (tDCS) treatment in order to induce a shift toward arousal in IH patients' cortex during the day. Every patients underwent a 4 weeks treatment (3 stimulations per week, for a total of 12 stimulations over a period of 28 days) with an assessment at the baseline and after treatment aimed to the evaluation of subjective daytime sleepiness, neurocognitive functions, and attentional domain tested by means of the Attentional Network Task (ANT). The dependent variables of the ANT are accuracy and reaction times, which represent the objective outcome of our study. A significant effect of tDCS' treatment in reducing EDS was found. Besides the amelioration in subjective EDS,  an objective improvement in RTs in all conditions of the ANT, in particular in the more difficult component, was observed. Our results indicate that tDCS may foster the management of EDS in IH, improving also the attentional domain.

From motor cortex to visual cortex: the application of noninvasive brain stimulation to amblyopia.

PubMed

Thompson, Benjamin; Mansouri, Behzad; Koski, Lisa; Hess, Robert F

2012-04-01

Noninvasive brain stimulation is a technique for inducing changes in the excitability of discrete neural populations in the human brain. A current model of the underlying pathological processes contributing to the loss of motor function after stroke has motivated a number of research groups to investigate the potential therapeutic application of brain stimulation to stroke rehabilitation. The loss of motor function is modeled as resulting from a combination of reduced excitability in the lesioned motor cortex and an increased inhibitory drive from the nonlesioned hemisphere over the lesioned hemisphere. This combination of impaired neural function and pathological suppression resonates with current views on the cause of the visual impairment in amblyopia. Here, we discuss how the rationale for using noninvasive brain stimulation in stroke rehabilitation can be applied to amblyopia, review a proof-of-principle study demonstrating that brain stimulation can temporarily improve amblyopic eye function, and propose future research avenues. Copyright © 2010 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 clinical context further investigation is needed to assess the reason for the reaction increase on CS–. If this negative side effect can be avoided, tDCS may be a tool to improve exposure-based anxiety therapies. PMID:29922133

The Effect of a Transcranial Channel as a Skull/Brain Interface in High-Definition Transcranial Direct Current Stimulation-A Computational Study.

PubMed

Seo, Hyeon; Kim, Hyoung-Ihl; Jun, Sung Chan

2017-01-13

A transcranial channel is an interface between the skull and brain; it consists of a biocompatible and highly conductive material that helps convey the current induced by transcranial direct current stimulation (tDCS) to the target area. However, it has been proposed only conceptually, and there has been no concrete study of its efficacy. In this work, we conducted a computational investigation of this conceptual transcranial model with high-definition tDCS, inducing focalized neuromodulation to determine whether inclusion of a transcranial channel performs effectively. To do so, we constructed an anatomically realistic head model and compartmental pyramidal neuronal models. We analyzed membrane polarization by extracellular stimulation and found that the inclusion of a transcranial channel induced polarization at the target area 11 times greater than conventional HD-tDCS without the transcranial channel. Furthermore, the stimulation effect of the transcranial channel persisted up to approximately 80%, even when the stimulus electrodes were displaced approximately 5 mm from the target area. We investigated the efficacy of the transcranial channel and found that greatly improved stimulation intensity and focality may be achieved. Thus, the use of these channels may be promising for clinical treatment.

Oscillating square wave Transcranial Direct Current Stimulation (tDCS) delivered during slow wave sleep does not improve declarative memory more than sham: A randomized sham controlled crossover study

PubMed Central

Sahlem, Gregory L.; Badran, Bashar W.; Halford, Jonathan J.; Williams, Nolan R.; Korte, Jeffrey E.; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L.; Runion, Jennifer; Bachman, David L.; Uhde, Thomas W.; Borckardt, Jeffery J.; George, Mark S.

2015-01-01

Background A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current wave form (square in our study, nearly sinusoidal in the original). Objective/Hypothesis Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Methods Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517mA/CM2, and oscillated between zero and maximal current at a frequency of 0.75Hz. Stimulation occurred during five-five minute blocks with one-minute inter-block intervals (25 minutes total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. Results There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1±3.0SD more associations) (sham = 3.8±3.1S.D more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6±2.7 S.D. correctly typed sequences) compared to sham stimulation (2.3± 2.2 S.D. correctly typed sequences)]. Conclusion In this study, we failed to find improvements in declarative or performance memory and could not replicate an earlier study using nearly identical settings. Specifically we failed to find a beneficial effect on either overnight declarative or non-declarative memory consolidation via square-wave oscillating tDCS intervention applied bi-frontally during early NREM sleep. It is unclear if the morphology of the tDCS pulse is critical in any memory related improvements. PMID:25795621

Oscillating Square Wave Transcranial Direct Current Stimulation (tDCS) Delivered During Slow Wave Sleep Does Not Improve Declarative Memory More Than Sham: A Randomized Sham Controlled Crossover Study.

PubMed

Sahlem, Gregory L; Badran, Bashar W; Halford, Jonathan J; Williams, Nolan R; Korte, Jeffrey E; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L; Runion, Jennifer; Bachman, David L; Uhde, Thomas W; Borckardt, Jeffery J; George, Mark S

2015-01-01

A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517 mA/cm(2), and oscillated between zero and maximal current at a frequency of 0.75 Hz. Stimulation occurred during five-five minute blocks with 1-min inter-block intervals (25 min total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1 ± 3.0 SD more associations) (sham = 3.8 ± 3.1 SD more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6 ± 2.7 SD correctly typed sequences) compared to sham stimulation (2.3 ± 2.2 SD correctly typed sequences)]. In this study, we failed to find improvements in declarative or performance memory and could not replicate an earlier study using nearly identical settings. Specifically we failed to find a beneficial effect on either overnight declarative or non-declarative memory consolidation via square-wave oscillating tDCS intervention applied bi-frontally during early NREM sleep. It is unclear if the morphology of the tDCS pulse is critical in any memory related improvements. Copyright © 2015 Elsevier Inc. All rights reserved.

Design of Electrical Stimulation Bioreactors for Cardiac Tissue Engineering

PubMed Central

Tandon, N.; Marsano, A.; Cannizzaro, C.; Voldman, J.; Vunjak-Novakovic, G.

2009-01-01

Electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. Carbon electrodes were found in past studies to have the best current injection characteristics. The goal of this study was to develop rational experimental design principles for the electrodes and stimulation regime, in particular electrode configuration, electrode ageing, and stimulation amplitude. Carbon rod electrodes were compared via electrochemical impedance spectroscopy (EIS) and we identified a safety range of 0 to 8 V/cm by comparing excitation thresholds and maximum capture rates for neonatal rat cardiomyocytes cultured with electrical stimulation. We conclude with recommendations for studies involving carbon electrodes for cardiac tissue engineering. PMID:19163486

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial.

PubMed

Wharen, Robert E; Okun, Michael S; Guthrie, Barton L; Uitti, Ryan J; Larson, Paul; Foote, Kelly; Walker, Harrison; Marshall, Frederick J; Schwalb, Jason; Ford, Blair; Jankovic, Joseph; Simpson, Richard; Dashtipour, Khashayar; Phibbs, Fenna; Neimat, Joseph S; Stewart, R Malcolm; Peichel, DeLea; Pahwa, Rajesh; Ostrem, Jill L

2017-07-01

This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET). A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures. 127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3). Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preliminary evidence for performance enhancement following parietal lobe stimulation in Developmental Dyscalculia.

PubMed

Iuculano, Teresa; Cohen Kadosh, Roi

2014-01-01

Nearly 7% of the population exhibit difficulties in dealing with numbers and performing arithmetic, a condition named Developmental Dyscalculia (DD), which significantly affects the educational and professional outcomes of these individuals, as it often persists into adulthood. Research has mainly focused on behavioral rehabilitation, while little is known about performance changes and neuroplasticity induced by the concurrent application of brain-behavioral approaches. It has been shown that numerical proficiency can be enhanced by applying a small-yet constant-current through the brain, a non-invasive technique named transcranial electrical stimulation (tES). Here we combined a numerical learning paradigm with transcranial direct current stimulation (tDCS) in two adults with DD to assess the potential benefits of this methodology to remediate their numerical difficulties. Subjects learned to associate artificial symbols to numerical quantities within the context of a trial and error paradigm, while tDCS was applied to the posterior parietal cortex (PPC). The first subject (DD1) received anodal stimulation to the right PPC and cathodal stimulation to the left PPC, which has been associated with numerical performance's improvements in healthy subjects. The second subject (DD2) received anodal stimulation to the left PPC and cathodal stimulation to the right PPC, which has been shown to impair numerical performance in healthy subjects. We examined two indices of numerical proficiency: (i) automaticity of number processing; and (ii) mapping of numbers onto space. Our results are opposite to previous findings with non-dyscalculic subjects. Only anodal stimulation to the left PPC improved both indices of numerical proficiency. These initial results represent an important step to inform the rehabilitation of developmental learning disabilities, and have relevant applications for basic and applied research in cognitive neuroscience, rehabilitation, and education.

Preliminary evidence for performance enhancement following parietal lobe stimulation in Developmental Dyscalculia

PubMed Central

Iuculano, Teresa; Cohen Kadosh, Roi

2014-01-01

Nearly 7% of the population exhibit difficulties in dealing with numbers and performing arithmetic, a condition named Developmental Dyscalculia (DD), which significantly affects the educational and professional outcomes of these individuals, as it often persists into adulthood. Research has mainly focused on behavioral rehabilitation, while little is known about performance changes and neuroplasticity induced by the concurrent application of brain-behavioral approaches. It has been shown that numerical proficiency can be enhanced by applying a small—yet constant—current through the brain, a non-invasive technique named transcranial electrical stimulation (tES). Here we combined a numerical learning paradigm with transcranial direct current stimulation (tDCS) in two adults with DD to assess the potential benefits of this methodology to remediate their numerical difficulties. Subjects learned to associate artificial symbols to numerical quantities within the context of a trial and error paradigm, while tDCS was applied to the posterior parietal cortex (PPC). The first subject (DD1) received anodal stimulation to the right PPC and cathodal stimulation to the left PPC, which has been associated with numerical performance's improvements in healthy subjects. The second subject (DD2) received anodal stimulation to the left PPC and cathodal stimulation to the right PPC, which has been shown to impair numerical performance in healthy subjects. We examined two indices of numerical proficiency: (i) automaticity of number processing; and (ii) mapping of numbers onto space. Our results are opposite to previous findings with non-dyscalculic subjects. Only anodal stimulation to the left PPC improved both indices of numerical proficiency. These initial results represent an important step to inform the rehabilitation of developmental learning disabilities, and have relevant applications for basic and applied research in cognitive neuroscience, rehabilitation, and education. PMID:24570659

The application of direct current electrical stimulation of the ear and cervical spine kinesitherapy in tinnitus treatment.

PubMed

Mielczarek, Marzena; Konopka, Wieslaw; Olszewski, Jurek

2013-02-01

The aim of the study was to evaluate the effectiveness of electrical stimulations of the hearing organ in tinnitus treatment adapting the frequency of stimulation according to tinnitus frequency, to assess the influence of cervical spine kinesitherapy on tinnitus, as well as to evaluate hearing after electrical stimulations alone and together with cervical spine kinesitherapy. The study comprised 80 tinnitus, sensorineural hearing loss patients (119 tinnitus ears) divided into two groups. In group I (n - 58 tinnitus ears) electrical stimulation of the hearing organ was performed, in group II (n - 61 tinnitus ears) electrical stimulation together with cervical spine kinesitherapy. Hydrotransmissive, selective electrical stimulations were conducted using direct, rectangular current. The passive electrode was placed on the forehead, the active--a silver probe--was immersed in the external ear canal in 0.9% saline solution. The treatment involved fifteen applications of electrical stimulations (each lasted for 4 min) administered three or four times a week (whole treatment lasted approximately 30 days). The evaluation of the results considered a case history (change from permanent to temporary tinnitus), questionnaires (the increase/decrease of the total points) and the audiometric evaluation of hearing level. Before the treatment, group I comprised 51 ears (87.93%) with permanent, and 7 ears (12.07%) with temporary tinnitus; group II - 55 ears (90.17%) with permanent and 6 ears (9.83%) with temporary tinnitus. After the treatment, in both groups the number of ears with permanent tinnitus decreased considerably obtaining the pauses or disappearing of tinnitus. Directly after the treatment, group I comprised 25 ears (43.11%) with permanent, and 10 ears (17.24%) with temporary tinnitus, in 23 ears (39.65%) tinnitus disappeared; group II - 33 ears (54.1%) with permanent and 11 ears (18.03%) with temporary tinnitus, in 17 ears (27.87%) tinnitus disappeared. Regarding questionnaires, improvement was observed in group I - in 43.11% of ears, in group II - 32.8%. In both groups audiometric improvement of hearing was recognized. (1) Electrical stimulation of the hearing organ, with the application of current frequencies according to tinnitus frequencies (selective electrical stimulation), was an efficient method in severe tinnitus treatment. (2) Cervical spine kinesitherapy in the treatment of tinnitus, using electrical stimulation, did not have any supporting influence. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

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.

Non-invasive brain stimulation for fine motor improvement after stroke: a meta-analysis.

PubMed

O'Brien, A T; Bertolucci, F; Torrealba-Acosta, G; Huerta, R; Fregni, F; Thibaut, A

2018-05-09

The aim of this study was to determine whether non-invasive brain stimulation (NIBS) techniques improve fine motor performance in stroke. We searched PubMed, EMBASE, Web of Science, SciELO and OpenGrey for randomized clinical trials on NIBS for fine motor performance in stroke patients and healthy participants. We computed Hedges' g for active and sham groups, pooled data as random-effects models and performed sensitivity analysis on chronicity, montage, frequency of stimulation and risk of bias. Twenty-nine studies (351 patients and 152 healthy subjects) were reviewed. Effect sizes in stroke populations for transcranial direct current stimulation and repeated transcranial magnetic stimulation were 0.31 [95% confidence interval (CI), 0.08-0.55; P = 0.010; Tau 2 , 0.09; I 2 , 34%; Q, 18.23; P = 0.110] and 0.46 (95% CI, 0.00-0.92; P = 0.05; Tau 2 , 0.38; I 2 , 67%; Q, 30.45; P = 0.007). The effect size of non-dominant healthy hemisphere transcranial direct current stimulation on non-dominant hand function was 1.25 (95% CI, 0.09-2.41; P = 0.04; Tau 2 , 1.26; I 2 , 93%; Q, 40.27; P < 0.001). Our results show that NIBS is associated with gains in fine motor performance in chronic stroke patients and healthy subjects. This supports the effects of NIBS on motor learning and encourages investigation to optimize their effects in clinical and research settings. © 2018 EAN.

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.

Effects of High-Definition and Conventional tDCS on Response Inhibition.

PubMed

Hogeveen, J; Grafman, J; Aboseria, M; David, A; Bikson, M; Hauner, K K

2016-01-01

Response inhibition is a critical executive function, enabling the adaptive control of behavior in a changing environment. The inferior frontal cortex (IFC) is considered to be critical for response inhibition, leading researchers to develop transcranial direct current stimulation (tDCS) montages attempting to target the IFC and improve inhibitory performance. However, conventional tDCS montages produce diffuse current through the brain, making it difficult to establish causality between stimulation of any one given brain region and resulting behavioral changes. Recently, high-definition tDCS (HD-tDCS) methods have been developed to target brain regions with increased focality relative to conventional tDCS. Remarkably few studies have utilized HD-tDCS to improve cognitive task performance, however, and no study has directly compared the behavioral effects of HD-tDCS to conventional tDCS. In the present study, participants received either HD-tDCS or conventional tDCS to the IFC during performance of a response inhibition task (stop-signal task, SST) or a control task (choice reaction time task, CRT). A third group of participants completed the same behavioral protocols, but received tDCS to a control site (mid-occipital cortex). Post-stimulation improvement in SST performance was analyzed as a function of tDCS group and the task performed during stimulation using both conventional and Bayesian parameter estimation analyses. Bayesian estimation of the effects of HD- and conventional tDCS to IFC relative to control site stimulation demonstrated enhanced response inhibition for both conditions. No improvements were found after control task (CRT) training in any tDCS condition. Results support the use of both HD- and conventional tDCS to the IFC for improving response inhibition, providing empirical evidence that HD-tDCS can be used to facilitate performance on an executive function task. Copyright © 2016 Elsevier Inc. All rights reserved.

Synchronous electrical stimulation of laryngeal muscles: an alternative for enhancing recovery of unilateral recurrent laryngeal nerve paralysis.

PubMed

Garcia Perez, Alejandro; Hernández López, Xochiquetzal; Valadez Jiménez, Víctor Manuel; Minor Martínez, Arturo; Ysunza, Pablo Antonio

2014-07-01

Although electrical stimulation of the larynx has been widely studied for treating voice disorders, its effectiveness has not been assessed under safety and comfortable conditions. This article describes design, theoretical issues, and preliminary evaluation of an innovative system for transdermal electrical stimulation of the larynx. The proposed design includes synchronization of electrical stimuli with laryngeal neuromuscular activity. To study whether synchronous electrical stimulation of the larynx could be helpful for improving voice quality in patients with dysphonia due to unilateral recurrent laryngeal nerve paralysis (URLNP). A 3-year prospective study was carried out at the Instituto Nacional de Rehabilitacion in the Mexico City. Ten patients were subjected to transdermal current electrical stimulation synchronized with the fundamental frequency of the vibration of the vocal folds during phonation. The stimulation was triggered during the phase of maximum glottal occlusion. A complete acoustic voice analysis was performed before and after the period of electrical stimulation. Acoustic analysis revealed significant improvements in all parameters after the stimulation period. Transdermal synchronous electrical stimulation of vocal folds seems to be a safe and reliable procedure for enhancing voice quality in patients with (URLNP). Copyright © 2014 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

Non-invasive vagus nerve stimulation acutely improves spontaneous cardiac baroreflex sensitivity in healthy young men: A randomized placebo-controlled trial.

PubMed

Antonino, Diego; Teixeira, André L; Maia-Lopes, Paulo M; Souza, Mayara C; Sabino-Carvalho, Jeann L; Murray, Aaron R; Deuchars, Jim; Vianna, Lauro C

Despite positive outcomes of transcutaneous vagus nerve stimulation (tVNS) via the auricular branch of the vagus nerve (ABVN), the mechanisms underlying these outcomes remain unclear. Additionally, previous studies have not been controlled the possible placebo effects of tVNS. To test the hypothesis that tVNS acutely improves spontaneous cardiac baroreflex sensitivity (cBRS) and autonomic modulation, and that these effects are specific to stimulation of ABVN. Thirteen healthy men (23±1yrs) were randomized across three experimental visits. In active tVNS, electrodes were placed on the tragus of the ear and electrical current was applied by using a Transcutaneous Electrical Nerve Stimulation device. A time-control visit was performed with the electrodes placed on tragus, but no current was applied (sham-T). Additionally, to avoid a placebo effect, another sham protocol was performed with same electrical current of the active visit, but the electrodes were placed on the ear lobe (an area without cutaneous nerve endings from the vagus - tLS). Beat-to-beat heart rate (HR) and blood pressure (BP) were monitored at rest, during stimulation (active, sham-T and tLS) and recovery. cBRS was measured via sequence technique. Both HR (HRV) and BP variability (BPV) were also measured. Arterial BP and BPV were not affected by any active or sham protocols (P > 0.05). Resting HR and LF/HF ratio of HRV decreased (Δ-3.4 ± 1% and Δ-15 ± 12%, P < 0.05, respectively) and cBRS increased (Δ24 ± 8%, P < 0.05) during active tVNS, but were unchanged during both sham protocols. tVNS acutely improves cBRS and autonomic modulation in healthy young men. Copyright © 2017 Elsevier Inc. All rights reserved.

Long-term efficacy and safety of sacral nerve stimulation for fecal incontinence.

PubMed

Mellgren, Anders; Wexner, Steven D; Coller, John A; Devroede, Ghislain; Lerew, Darin R; Madoff, Robert D; Hull, Tracy

2011-09-01

Sacral nerve stimulation is effective in the treatment of urinary incontinence and is currently under Food and Drug Administration review in the United States for fecal incontinence. Previous reports have focused primarily on short-term results of sacral nerve stimulation for fecal incontinence. The present study reports the long-term effectiveness and safety of sacral nerve stimulation for fecal incontinence in a large prospective multicenter study. Patients with fecal incontinent episodes more than twice per week were offered participation in this multicentered prospective trial. Patients showing ≥ 50% improvement during test stimulation were offered chronic implantation of the InterStim Therapy system (Medtronic; Minneapolis, MN). The aims of the current report were to provide 3-year follow-up data on patients from that study who underwent sacral nerve stimulation and were monitored under the rigors of an Food and Drug Administration-approved investigational protocol. One hundred thirty-three patients underwent test stimulation with a 90% success rate, of whom 120 (110 females) with a mean age of 60.5 years and a mean duration of fecal incontinence of 7 years received chronic implantation. Mean length of follow-up was 3.1 (range, 0.2-6.1) years, with 83 patients completing all or part of the 3-year follow-up assessment. At 3 years follow-up, 86% of patients (P < .0001) reported ≥ 50% reduction in the number of incontinent episodes per week compared with baseline and the number of incontinent episodes per week decreased from a mean of 9.4 at baseline to 1.7. Perfect continence was achieved in 40% of subjects. The therapy also improved the fecal incontinence severity index. Sacral nerve stimulation had a positive impact on the quality of life, as evidenced by significant improvements in all 4 scales of the Fecal Incontinence Quality of Life instrument at 12, 24, and 36 months of follow-up. The most common device- or therapy-related adverse events through the mean 36 months of follow-up included implant site pain (28%), paresthesia (15%), change in the sensation of stimulation (12%), and infection (10%). There were no reported unanticipated adverse device effects associated with sacral nerve stimulation therapy. Sacral nerve stimulation using InterStim Therapy is a safe and effective treatment for patients with fecal incontinence. These data support long-term safety and effectiveness to 36 months.

Vestibular Stochastic Resonance as a Method to Improve Balance Function: Optimization of Stimulus Characteristics

NASA Technical Reports Server (NTRS)

Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Peters, Brian; Wood, Scott; Serrador, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob

2010-01-01

Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant sensory signals. Application of imperceptible SR noise coupled with sensory input through the proprioceptive, visual, or vestibular sensory systems has been shown to improve motor function. Specifically, studies have shown that that vestibular electrical stimulation by imperceptible stochastic noise, when applied to normal young and elderly subjects, significantly improved their ocular stabilization reflexes in response to whole-body tilt as well as balance performance during postural disturbances. The goal of this study was to optimize the characteristics of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standardized balance task of standing on a block of 10 cm thick medium density foam with their eyes closed for a total of 40 seconds. Stochastic electrical stimulation was applied to the vestibular system through electrodes placed over the mastoid process behind the ears during the last 20 seconds of the test period. A custom built constant current stimulator with subject isolation delivered the stimulus. Stimulation signals were generated with frequencies in the bandwidth of 1-2 Hz and 0.01-30 Hz. Amplitude of the signals were varied in the range of 0- +/-700 micro amperes with the RMS of the signal increased by 30 micro amperes for each 100 micro amperes increase in the current range. Balance performance was measured using a force plate under the foam block and inertial motion sensors placed on the torso and head segments. Preliminary results indicate that balance performance is improved in the range of 10-25% compared to no stimulation conditions. Subjects improved their performance consistently across the blocks of stimulation. Further the signal amplitude at which the performance was maximized was different in the two frequency ranges. Optimization of the frequency and amplitude of the signal characteristics of the stochastic noise signals on maximizing balance performance will have a significant impact in its development as a unique system to aid recovery of function in astronauts after long duration space flight or for people with balance disorders.

Improvement of Olfactory Function With High Frequency Non-invasive Auricular Electrostimulation in Healthy Humans

PubMed Central

Maharjan, Ashim; Wang, Eunice; Peng, Mei; Cakmak, Yusuf O.

2018-01-01

In past literature on animal models, invasive vagal nerve stimulation using high frequencies has shown to be effective at modulating the activity of the olfactory bulb (OB). Recent advances in invasive vagal nerve stimulation in humans, despite previous findings in animal models, used low frequency stimulation and found no effect on the olfactory functioning. The present article aimed to test potential effects of non-invasive, high and low frequency vagal nerve stimulation in humans, with supplementary exploration of the orbitofrontal cortex using near-infrared spectroscopy (NIRS). Healthy, male adult participants (n = 18) performed two olfactory tests [odor threshold test (OTT) and supra-threshold test (STT)] before and after receiving high-, low frequency vagal nerve stimulation and placebo (no stimulation). Participant's olfactory functioning was monitored using NIRS, and assessed with two behavioral olfactory tests. NIRS data of separate stimulation parameters were statistically analyzed using repeated-measures ANOVA across different stages. Data from olfactory tests were analyzed using paired parametric and non-parametric statistical tests. Only high frequency, non-invasive vagal nerve stimulation was able to positively modulate the performance of the healthy participants in the STT (p = 0.021, Wilcoxon sign-ranked test), with significant differences in NIRS (p = 0.014, post-hoc with Bonferroni correction) recordings of the right hemispheric, orbitofrontal cortex. The results from the current article implore further exploration of the neurocircuitry involved under vagal nerve stimulation and the effects of non-invasive, high frequency, vagal nerve stimulation toward olfactory dysfunction which showcase in Parkinson's and Alzheimer's Diseases. Despite the sufficient effect size (moderate effect, correlation coefficient (r): 0.39 for the STT) of the current study, future research should replicate the current findings with a larger cohort. PMID:29740266

Improvement of Olfactory Function With High Frequency Non-invasive Auricular Electrostimulation in Healthy Humans.

PubMed

Maharjan, Ashim; Wang, Eunice; Peng, Mei; Cakmak, Yusuf O

2018-01-01

In past literature on animal models, invasive vagal nerve stimulation using high frequencies has shown to be effective at modulating the activity of the olfactory bulb (OB). Recent advances in invasive vagal nerve stimulation in humans, despite previous findings in animal models, used low frequency stimulation and found no effect on the olfactory functioning. The present article aimed to test potential effects of non-invasive, high and low frequency vagal nerve stimulation in humans, with supplementary exploration of the orbitofrontal cortex using near-infrared spectroscopy (NIRS). Healthy, male adult participants ( n = 18) performed two olfactory tests [odor threshold test (OTT) and supra-threshold test (STT)] before and after receiving high-, low frequency vagal nerve stimulation and placebo (no stimulation). Participant's olfactory functioning was monitored using NIRS, and assessed with two behavioral olfactory tests. NIRS data of separate stimulation parameters were statistically analyzed using repeated-measures ANOVA across different stages. Data from olfactory tests were analyzed using paired parametric and non-parametric statistical tests. Only high frequency, non-invasive vagal nerve stimulation was able to positively modulate the performance of the healthy participants in the STT ( p = 0.021, Wilcoxon sign-ranked test), with significant differences in NIRS ( p = 0.014, post-hoc with Bonferroni correction ) recordings of the right hemispheric, orbitofrontal cortex. The results from the current article implore further exploration of the neurocircuitry involved under vagal nerve stimulation and the effects of non-invasive, high frequency, vagal nerve stimulation toward olfactory dysfunction which showcase in Parkinson's and Alzheimer's Diseases. Despite the sufficient effect size (moderate effect, correlation coefficient (r): 0.39 for the STT) of the current study, future research should replicate the current findings with a larger cohort.

[Are Visual Field Defects Reversible? - Visual Rehabilitation with Brains].

PubMed

Sabel, B A

2017-02-01

Visual field defects are considered irreversible because the retina and optic nerve do not regenerate. Nevertheless, there is some potential for recovery of the visual fields. This can be accomplished by the brain, which analyses and interprets visual information and is able to amplify residual signals through neuroplasticity. Neuroplasticity refers to the ability of the brain to change its own functional architecture by modulating synaptic efficacy. This is actually the neurobiological basis of normal learning. Plasticity is maintained throughout life and can be induced by repetitively stimulating (training) brain circuits. The question now arises as to how plasticity can be utilised to activate residual vision for the treatment of visual field loss. Just as in neurorehabilitation, visual field defects can be modulated by post-lesion plasticity to improve vision in glaucoma, diabetic retinopathy or optic neuropathy. Because almost all patients have some residual vision, the goal is to strengthen residual capacities by enhancing synaptic efficacy. New treatment paradigms have been tested in clinical studies, including vision restoration training and non-invasive alternating current stimulation. While vision training is a behavioural task to selectively stimulate "relative defects" with daily vision exercises for the duration of 6 months, treatment with alternating current stimulation (30 min. daily for 10 days) activates and synchronises the entire retina and brain. Though full restoration of vision is not possible, such treatments improve vision, both subjectively and objectively. This includes visual field enlargements, improved acuity and reaction time, improved orientation and vision related quality of life. About 70 % of the patients respond to the therapies and there are no serious adverse events. Physiological studies of the effect of alternating current stimulation using EEG and fMRI reveal massive local and global changes in the brain. These include local activation of the visual cortex and global reorganisation of neuronal brain networks. Because modulation of neuroplasticity can strengthen residual vision, the brain deserves a better reputation in ophthalmology for its role in visual rehabilitation. For patients, there is now more light at the end of the tunnel, because vision loss in some areas of the visual field defect is indeed reversible. Georg Thieme Verlag KG Stuttgart · New York.

Positive effects of transcranial direct current stimulation in adult patients with attention-deficit/hyperactivity disorder - A pilot randomized controlled study.

PubMed

Cachoeira, Carolina Tosetto; Leffa, Douglas Teixeira; Mittelstadt, Suzana Doneda; Mendes, Lorenna Sena Teixeira; Brunoni, Andre R; Pinto, Jairo Vinicius; Blazius, Vtor; Machado, Vitoria; Bau, Claiton Henrique Dotto; Rohde, Luis Augusto; Grevet, Eugenio Horacio; Schestatsky, Pedro

2017-01-01

Almost 30% of adult patients with attention-deficit/hyperactivity disorder (ADHD) do not respond or tolerate standard pharmacological interventions. Few clinical investigations addressed the efficacy and tolerability of transcranial direct current stimulation (tDCS), a non-invasive neuromodulatory technique, in the disorder. We performed a double-blind, sham-controlled randomized clinical trial in 17 patients with ADHD. The set up for tDCS was the following: 2mA/20min/day for 5 days with the anode over the right dorsolateral prefrontal cortex and cathode over the left dorsolateral prefrontal cortex. ADHD symptoms were measured by the Adult ADHD Self-Report Scale (ASRS) and impairment with the Sheehan Disability Scale (SDS) in four different time points after stimulation. Participants achieved significant lower ASRS inattention and SDS scores after active tDCS in comparison with sham stimulation group. In addition, we detected a trend for a lower ASRS total score in the active tDCS group. Follow up data analysis revealed a positive interaction between time and treatment in both ASRS inattention, SDS and ASRS total scores. Short-term application of tDCS in adult patients with ADHD improved their symptoms, and this improvement persisted after the end of the stimulation. Future studies with larger sample sizes are needed. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Therapeutic options to enhance coma arousal after traumatic brain injury: state of the art of current treatments to improve coma recovery.

PubMed

Cossu, Giulia

2014-04-01

Traumatic brain injury is a leading cause of death and disability. Optimizing the recovery from coma is a priority in seeking to improve patients' functional outcomes. Standards of care have not been established: pharmacological interventions, right median nerve and sensory stimulation, dorsal column stimulation (DCS), deep brain stimulation, transcranial magnetic stimulation, hyperbaric oxygen therapy and cell transplantation have all been utilized with contrasting results. The aim of this review is to clarify the indications for the various techniques and to guide the clinical practice towards an earlier coma arousal. A systematic bibliographic search was undertaken using the principal search engines (Pubmed, Embase, Ovid and Cochrane databases) to locate the most pertinent studies. Traumatic injury is a highly individualized process, and subsequent impairments are dependent on multiple factors: this heterogeneity influences and determines therapeutic responses to the various interventions.

Technological advances in the surgical treatment of movement disorders.

PubMed

Gross, Robert E; McDougal, Margaret E

2013-08-01

Technological innovations have driven the advancement of the surgical treatment of movement disorders, from the invention of the stereotactic frame to the adaptation of deep brain stimulation (DBS). Along these lines, this review will describe recent advances in inserting neuromodulation modalities, including DBS, to the target, and in the delivery of therapy at the target. Recent radiological advances are altering the way that DBS leads are targeted and inserted, by refining the ability to visualize the subcortical targets using high-field strength magnetic resonance imaging and other innovations, such as diffusion tensor imaging, and the development of novel targeting devices enabling purely anatomical implantations without the need for neurophysiological monitoring. New portable computed tomography scanners also are facilitating lead implantation without monitoring, as well as improving radiological verification of DBS lead location. Advances in neurophysiological mapping include efforts to develop automatic target verification algorithms, and probabilistic maps to guide target selection. The delivery of therapy at the target is being improved by the development of the next generation of internal pulse generators (IPGs). These include constant current devices that mitigate the variability introduced by impedance changes of the stimulated tissue and, in the near future, devices that deliver novel stimulation patterns with improved efficiency. Closed-loop adaptive IPGs are being tested, which may tailor stimulation to ongoing changes in the nervous system, reflected in biomarkers continuously recorded by the devices. Finer-grained DBS leads, in conjunction with new IPGs and advanced programming tools, may offer improved outcomes via current steering algorithms. Finally, even thermocoagulation-essentially replaced by DBS-is being advanced by new minimally-invasive approaches that may improve this therapy for selected patients in whom it may be preferred. Functional neurosurgery has a history of being driven by technological innovation, a tradition that continues into its future.

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.

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.

Parietotemporal Stimulation Affects Acquisition of Novel Grapheme-Phoneme Mappings in Adult Readers

PubMed Central

Younger, Jessica W.; Booth, James R.

2018-01-01

Neuroimaging work from developmental and reading intervention research has suggested a cause of reading failure may be lack of engagement of parietotemporal cortex during initial acquisition of grapheme-phoneme (letter-sound) mappings. Parietotemporal activation increases following grapheme-phoneme learning and successful reading intervention. Further, stimulation of parietotemporal cortex improves reading skill in lower ability adults. However, it is unclear whether these improvements following stimulation are due to enhanced grapheme-phoneme mapping abilities. To test this hypothesis, we used transcranial direct current stimulation (tDCS) to manipulate parietotemporal function in adult readers as they learned a novel artificial orthography with new grapheme-phoneme mappings. Participants received real or sham stimulation to the left inferior parietal lobe (L IPL) for 20 min before training. They received explicit training over the course of 3 days on 10 novel words each day. Learning of the artificial orthography was assessed at a pre-training baseline session, the end of each of the three training sessions, an immediate post-training session and a delayed post-training session about 4 weeks after training. Stimulation interacted with baseline reading skill to affect learning of trained words and transfer to untrained words. Lower skill readers showed better acquisition, whereas higher skill readers showed worse acquisition, when training was paired with real stimulation, as compared to readers who received sham stimulation. However, readers of all skill levels showed better maintenance of trained material following parietotemporal stimulation, indicating a differential effect of stimulation on initial learning and consolidation. Overall, these results indicate that parietotemporal stimulation can enhance learning of new grapheme-phoneme relationships in readers with lower reading skill. Yet, while parietotemporal function is critical to new learning, its role in continued reading improvement likely changes as readers progress in skill. PMID:29628882

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.

Computational Modeling and Neuroimaging Techniques for Targeting during Deep Brain Stimulation

PubMed Central

Sweet, Jennifer A.; Pace, Jonathan; Girgis, Fady; Miller, Jonathan P.

2016-01-01

Accurate surgical localization of the varied targets for deep brain stimulation (DBS) is a process undergoing constant evolution, with increasingly sophisticated techniques to allow for highly precise targeting. However, despite the fastidious placement of electrodes into specific structures within the brain, there is increasing evidence to suggest that the clinical effects of DBS are likely due to the activation of widespread neuronal networks directly and indirectly influenced by the stimulation of a given target. Selective activation of these complex and inter-connected pathways may further improve the outcomes of currently treated diseases by targeting specific fiber tracts responsible for a particular symptom in a patient-specific manner. Moreover, the delivery of such focused stimulation may aid in the discovery of new targets for electrical stimulation to treat additional neurological, psychiatric, and even cognitive disorders. As such, advancements in surgical targeting, computational modeling, engineering designs, and neuroimaging techniques play a critical role in this process. This article reviews the progress of these applications, discussing the importance of target localization for DBS, and the role of computational modeling and novel neuroimaging in improving our understanding of the pathophysiology of diseases, and thus paving the way for improved selective target localization using DBS. PMID:27445709

Investigation of Stimulation-Response Relationships for Complex Fracture Systems in Enhanced Geothermal Reservoirs

DOE Data Explorer

Fu, Pengcheng; Johnson, Scott M.; Carrigan, Charles R.

2011-01-01

Hydraulic fracturing is currently the primary method for stimulating low-permeability geothermal reservoirs and creating Enhanced (or Engineered) Geothermal Systems (EGS) with improved permeability and heat production efficiency. Complex natural fracture systems usually exist in the formations to be stimulated and it is therefore critical to understand the interactions between existing fractures and newly created fractures before optimal stimulation strategies can be developed. Our study aims to improve the understanding of EGS stimulation-response relationships by developing and applying computer-based models that can effectively reflect the key mechanisms governing interactions between complex existing fracture networks and newly created hydraulic fractures. In this paper, we first briefly describe the key modules of our methodology, namely a geomechanics solver, a discrete fracture flow solver, a rock joint response model, an adaptive remeshing module, and most importantly their effective coupling. After verifying the numerical model against classical closed-form solutions, we investigate responses of reservoirs with different preexisting natural fractures to a variety of stimulation strategies. The factors investigated include: the in situ stress states (orientation of the principal stresses and the degree of stress anisotropy), pumping pressure, and stimulation sequences of multiple wells.

Unilateral pedunculopontine stimulation improves falls in Parkinson's disease.

PubMed

Moro, Elena; Hamani, Clement; Poon, Yu-Yan; Al-Khairallah, Thamar; Dostrovsky, Jonathan O; Hutchison, William D; Lozano, Andres M

2010-01-01

Postural instability and falls are a major source of disability in patients with advanced Parkinson's disease. These problems are currently not well addressed by either pharmacotherapy nor by subthalamic nucleus deep-brain stimulation surgery. The neuroanatomical substrates of posture and gait are poorly understood but a number of important observations suggest a major role for the pedunculopontine nucleus and adjacent areas in the brainstem. We conducted a double-blinded evaluation of unilateral pedunculopontine nucleus deep-brain stimulation in a pilot study in six advanced Parkinson's disease patients with significant gait and postural abnormalities. There was no significant difference in the double-blinded on versus off stimulation Unified Parkinson's Disease Rating Scale motor scores after 3 or 12 months of continuous stimulation and no improvements in the Unified Parkinson's Disease Rating Scale part III scores compared to baseline. In contrast, patients reported a significant reduction in falls in the on and off medication states both at 3 and 12 months after pedunculopontine nucleus deep-brain stimulation as captured in the Unified Parkinson's Disease Rating Scale part II scores. Our results suggest that pedunculopontine nucleus deep-brain stimulation may be effective in preventing falls in patients with advanced Parkinson's disease but that further evaluation of this procedure is required.

Current density distributions, field distributions and impedance analysis of segmented deep brain stimulation electrodes

NASA Astrophysics Data System (ADS)

Wei, Xuefeng F.; Grill, Warren M.

2005-12-01

Deep brain stimulation (DBS) electrodes are designed to stimulate specific areas of the brain. The most widely used DBS electrode has a linear array of 4 cylindrical contacts that can be selectively turned on depending on the placement of the electrode and the specific area of the brain to be stimulated. The efficacy of DBS therapy can be improved by localizing the current delivery into specific populations of neurons and by increasing the power efficiency through a suitable choice of electrode geometrical characteristics. We investigated segmented electrode designs created by sectioning each cylindrical contact into multiple rings. Prototypes of these designs, made with different materials and larger dimensions than those of clinical DBS electrodes, were evaluated in vitro and in simulation. A finite element model was developed to study the effects of varying the electrode characteristics on the current density and field distributions in an idealized electrolytic medium and in vitro experiments were conducted to measure the electrode impedance. The current density over the electrode surface increased towards the edges of the electrode, and multiple edges increased the non-uniformity of the current density profile. The edge effects were more pronounced over the end segments than over the central segments. Segmented electrodes generated larger magnitudes of the second spatial difference of the extracellular potentials, and thus required lower stimulation intensities to achieve the same level of neuronal activation as solid electrodes. For a fixed electrode conductive area, increasing the number of segments (edges) decreased the impedance compared to a single solid electrode, because the average current density over the segments increased. Edge effects played a critical role in determining the current density distributions, neuronal excitation patterns, and impedance of cylindrical electrodes, and segmented electrodes provide a means to increase the efficiency of DBS.

Placebo-controlled vagus nerve stimulation paired with tones in a patient with refractory tinnitus: a case report.

PubMed

De Ridder, Dirk; Kilgard, Michael; Engineer, Navzer; Vanneste, Sven

2015-04-01

Classical neuromodulation consists of applying electrical or magnetic stimuli to the nervous system to modulate ongoing activity and connectivity. However, recently, an exciting novel neuromodulation technique was developed in which stimulation of the vagal nerve was paired with simultaneous presentation of tones, demonstrating that it reverses a tinnitus percept in noise-exposed rats. To determine whether this therapy could also be effective in humans, we delivered a similar therapy in a patient with chronic tinnitus unresponsive to previous therapies. In this report, we describe the case of a 59-year-old man who suffered from bilateral tinnitus for 14 years that arose after a cervical fusion operation. Pharmacotherapy, transcranial magnetic stimulation, transcranial direct current stimulation, neurofeedback, and bilateral auditory cortex stimulation via implanted electrodes did not improve the tinnitus. After implanting the vagal nerve stimulator, the patient received daily vagus nerve stimulation tone pairings for 4 weeks in a non-placebo-controlled way. At the end of therapy, the patient experienced a significant reduction in tinnitus symptoms that lasted for 2 months after treatment. Tinnitus Handicap Inventory and Tinnitus Reaction Questionnaire were reduced by 48% and 68%, respectively. Symptoms of depression were also improved by 40%, as quantified by the Beck Depression Inventory. Three months after ending therapy, placebo stimulation was performed consisting of only tone presentation without the simultaneous electrical stimuli. This resulted in further continuation of the gradual relapse to the baseline state, without renewed improvement. Our results suggest that vagus nerve stimulation paired with tones could become an effective therapy for the treatment of tinnitus.

Efficacy and Safety of Pedunculopontine Nuclei (PPN) Deep Brain Stimulation in the Treatment of Gait Disorders: A Meta-Analysis of Clinical Studies.

PubMed

Golestanirad, Laleh; Elahi, Behzad; Graham, Simon J; Das, Sunit; Wald, Lawrence L

2016-01-01

Pedunculopontine nucleus (PPN) has complex reciprocal connections with basal ganglia, especially with internal globus pallidus and substantia nigra, and it has been postulated that PPN stimulation may improve gait instability and freezing of gait. In this meta-analysis, we will assess the evidence for PPN deep brain stimulation in treatment of gait and motor abnormalities especially focusing on Parkinson disease patients. PubMed and Scopus electronic databases were searched for related studies published before February 2014. Medline (1966-2014), Embase (1974-2010), CINAHL, Web of Science, Scopus bibliographic, and Google Scholar databases (1960-2014) were also searched for studies investigating effect of PPN deep brain stimulation in treatment of postural and postural instability and total of ten studies met the inclusion criteria for this analysis. Our findings showed a significant improvement in postural instability (p<0.001) and motor symptoms of Parkinson disease on and off medications (p<0.05), but failed to show improvement in freezing of gait. Despite significant improvement in postural instability observed in included studies, evidence from current literature is not sufficient to generalize these findings to the majority of patients.

A study protocol for a single-blind, randomized controlled trial of adjunctive transcranial direct current stimulation (tDCS) for chronic pain among patients receiving specialized, inpatient multimodal pain management.

PubMed

Janice Jimenez-Torres, G; Weinstein, Benjamin L; Walker, Cory R; Christopher Fowler, J; Ashford, Philippa; Borckardt, Jeffrey J; Madan, Alok

2017-03-01

Available treatments for chronic pain (CP) are modestly effective or associated with iatrogenic harm. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that may be an effective, adjunctive treatment to non-opioid therapies. In this randomized control trial (RCT), we compare adjunctive active versus sham tDCS among patients in a multimodal inpatient pain management program. The primary objectives of the RCT are to improve pain tolerance and subjective pain experience. Patients admitted to the Pain Management Program at The Menninger Clinic in Houston, Texas are eligible for this trial. Eighty-four participants will be randomized (1:1) into a single-blind, 2×12 (group×time) controlled trial. A battery-powered direct and constant current stimulator (Soterix Medical Inc. 2014) delivers anodal stimulation over the left dorsolateral prefrontal cortex (DLPFC) and cathodal stimulation over the right DLPFC. Active tDCS is applied by supplying a 2mA current for 20min/session over 10 sessions. Participants complete self-report and performance-based assessments on a weekly basis just prior to brain stimulation. Self-report assessments are collected via Chronic Pain Tracker version 3.6, an iPad interfaced application. The performance-based pain tolerance task is completed through the cold presser task. Interventions with cross-symptomatic therapeutic potential are absolutely essential in the context of CP, in which psychiatric comorbidity is the norm. Modalities that can be used in tandem with evidence-based, non-opioid therapies have the potential to have a synergistic effect, resulting in increased effectiveness of what have been modestly effective treatments to date. Copyright © 2017 Elsevier Inc. 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.

Polarity-dependent improvement of maximal-effort sprint cycling performance by direct current stimulation of the central nervous system.

PubMed

Sasada, Syusaku; Endoh, Takashi; Ishii, Tomoya; Komiyama, Tomoyoshi

2017-09-14

Sprint motor performance, such as in short-distance running or cycling, gradually decreases after reaching a maximum speed or cadence. This may be attributed to the central nervous system. Brain stimulation studies have recently revealed the plastic nature of the human brain and spinal cord, but it is unclear how direct current stimulation (DCS) affects sprint motor performance. To address this issue, we investigated DCS's effect on healthy volunteers' sprint cycling performance. DCS was applied to the lumbar spinal cord (3mA) or the leg area of the motor cortex (2mA) for 15min with 3 different polarities: anodal, cathodal, and sham. After DCS, the subjects performed maximal-effort sprint cycling for 30s under a constant load. Pooled mean power during the 30s was significantly greater after cathodal transcutaneous spinal DCS to the lumbar spinal cord (tsDCS) than anodal or sham tsDCS. The improvement with cathodal stimulation was notable both 0-5 and 20-25s after the performance onset. There were no significant inter-conditional differences in peak power. Pooled mean power was significantly greater after anodal transcranial DCS to the motor cortex (tDCS) than after cathodal tDCS, although mean powers of anodal and sham tDCS were not significantly different. The increase in mean power after cathodal tsDCS could result from a reduction in central fatigue. This stimulus method might improve sprint performance. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Evaluation of focused multipolar stimulation for cochlear implants in acutely deafened cats

NASA Astrophysics Data System (ADS)

George, Shefin S.; Wise, Andrew K.; Shivdasani, Mohit N.; Shepherd, Robert K.; Fallon, James B.

2014-12-01

Objective. The conductive nature of the fluids and tissues of the cochlea can lead to broad activation of spiral ganglion neurons using contemporary cochlear implant stimulation configurations such as monopolar (MP) stimulation. The relatively poor spatial selectivity is thought to limit implant performance, particularly in noisy environments. Several current focusing techniques have been proposed to reduce the spread of activation with the aim towards achieving improved clinical performance. Approach. The present research evaluated the efficacy of focused multipolar (FMP) stimulation, a relatively new focusing technique in the cochlea, and compared its efficacy to both MP stimulation and tripolar (TP) stimulation. The spread of neural activity across the inferior colliculus (IC), measured by recording the spatial tuning curve, was used as a measure of spatial selectivity. Adult cats (n = 6) were acutely deafened and implanted with an intracochlear electrode array before multi-unit responses were recorded across the cochleotopic gradient of the contralateral IC. Recordings were made in response to acoustic and electrical stimulation using the MP, TP and FMP configurations. Main results. FMP and TP stimulation resulted in greater spatial selectivity than MP stimulation. However, thresholds were significantly higher (p < 0.001) for FMP and TP stimulation compared to MP stimulation. There were no differences found in spatial selectivity and threshold between FMP and TP stimulation. Significance. The greater spatial selectivity of FMP and TP stimulation would be expected to result in improved clinical performance. However, further research will be required to demonstrate the efficacy of these modes of stimulation after longer durations of deafness.

Onsite-effects of dual-hemisphere versus conventional single-hemisphere transcranial direct current stimulation: A functional MRI study.

PubMed

Kwon, Yong Hyun; Jang, Sung Ho

2012-08-25

We performed functional MRI examinations in six right-handed healthy subjects. During functional MRI scanning, transcranial direct current stimulation was delivered with the anode over the right primary sensorimotor cortex and the cathode over the left primary sensorimotor cortex using dual-hemispheric transcranial direct current stimulation. This was compared to a cathode over the left supraorbital area using conventional single-hemispheric transcranial direct current stimulation. Voxel counts and blood oxygenation level-dependent signal intensities in the right primary sensorimotor cortex regions were estimated and compared between the two transcranial direct current stimulation conditions. Our results showed that dual-hemispheric transcranial direct current stimulation induced greater cortical activities than single-hemispheric transcranial direct current stimulation. These findings suggest that dual-hemispheric transcranial direct current stimulation may provide more effective cortical stimulation than single-hemispheric transcranial direct current stimulation.

Onsite-effects of dual-hemisphere versus conventional single-hemisphere transcranial direct current stimulation

PubMed Central

Kwon, Yong Hyun; Jang, Sung Ho

2012-01-01

We performed functional MRI examinations in six right-handed healthy subjects. During functional MRI scanning, transcranial direct current stimulation was delivered with the anode over the right primary sensorimotor cortex and the cathode over the left primary sensorimotor cortex using dual-hemispheric transcranial direct current stimulation. This was compared to a cathode over the left supraorbital area using conventional single-hemispheric transcranial direct current stimulation. Voxel counts and blood oxygenation level-dependent signal intensities in the right primary sensorimotor cortex regions were estimated and compared between the two transcranial direct current stimulation conditions. Our results showed that dual-hemispheric transcranial direct current stimulation induced greater cortical activities than single-hemispheric transcranial direct current stimulation. These findings suggest that dual-hemispheric transcranial direct current stimulation may provide more effective cortical stimulation than single-hemispheric transcranial direct current stimulation. PMID:25624815

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation

PubMed Central

Zanto, Theodore P.; van Schouwenburg, Martine R.; Gazzaley, Adam

2017-01-01

Multitasking is associated with the generation of stimulus-locked theta (4–7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13–30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement. PMID:28562642

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation.

PubMed

Hsu, Wan-Yu; Zanto, Theodore P; van Schouwenburg, Martine R; Gazzaley, Adam

2017-01-01

Multitasking is associated with the generation of stimulus-locked theta (4-7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13-30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement.

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.

[Significance of Matrix-augmented Bone Marrow Stimulation for Treatment of Cartilage Defects of the Knee: A Consensus Statement of the DGOU Working Group on Tissue Regeneration].

PubMed

Niemeyer, Philipp; Becher, Christoph; Buhs, Matthias; Fickert, Stefan; Gelse, Kolja; Günther, Daniel; Kaelin, Raphael; Kreuz, Peter; Lützner, Jörg; Nehrer, Stefan; Madry, Henning; Marlovits, Stefan; Mehl, Julian; Ott, Henning; Pietschmann, Matthias; Spahn, Gunther; Tischer, Thomas; Volz, Martin; Walther, Markus; Welsch, Götz; Zellner, Johannes; Zinser, Wolfgang; Angele, Peter

2018-06-18

Surgical principles for treatment of full-thickness cartilage defects of the knee include bone marrow stimulation techniques (i.e. arthroscopic microfracturing) and transplantation techniques (i.e. autologous chondrocyte implantation and osteochondral transplantation). On the basis of increasing scientific evidence, indications for these established therapeutical concepts have been specified and clear recommendations for practical use have been given. Within recent years, matrix-augmented bone marrow stimulation has been established as a new treatment concept for chondral lesions. To date, scientific evidence is limited and specific indications are still unclear. The present paper gives an overview of available products as well as preclinical and clinical scientific evidence. On the basis of the present evidence and an expert consensus from the "Working Group on Tissue Regeneration" of the German Orthopaedic and Trauma Society (DGOU), indications are specified and recommendations for the use of matrix-augmented bone marrow stimulation are given. In principle, it can be stated that the various products offered in this field differ considerably in terms of the number and quality of related studies (evidence level). Against the background of the current data situation, their application is currently seen in the border area between cell transplantation and bone marrow stimulation techniques, but also as an improvement on traditional bone marrow stimulation within the indication range of microfracturing. The recommendations of the Working Group have preliminary character and require re-evaluation after improvement of the study situation. Georg Thieme Verlag KG Stuttgart · New York.

Occipital Nerve Field Transcranial Direct Current Stimulation Normalizes Imbalance Between Pain Detecting and Pain Inhibitory Pathways in Fibromyalgia.

PubMed

De Ridder, Dirk; Vanneste, Sven

2017-04-01

Occipital nerve field (OCF) stimulation with subcutaneously implanted electrodes is used to treat headaches, more generalized pain, and even failed back surgery syndrome via unknown mechanisms. Transcranial direct current stimulation (tDCS) can predict the efficacy of implanted electrodes. The purpose of this study is to unravel the neural mechanisms involved in global pain suppression, mediated by occipital nerve field stimulation, within the realm of fibromyalgia. Nineteen patients with fibromyalgia underwent a placebo-controlled OCF tDCS. Electroencephalograms were recorded at baseline after active and sham stimulation. In comparison with healthy controls, patients with fibromyalgia demonstrate increased dorsal anterior cingulate cortex, increased premotor/dorsolateral prefrontal cortex activity, and an imbalance between pain-detecting dorsal anterior cingulate cortex and pain-suppressing pregenual anterior cingulate cortex activity, which is normalized after active tDCS but not sham stimulation associated with increased pregenual anterior cingulate cortex activation. The imbalance improvement between the pregenual anterior cingulate cortex and the dorsal anterior cingulate cortex is related to clinical changes. An imbalance assumes these areas communicate and, indeed, abnormal functional connectivity between the dorsal anterior cingulate cortex and pregenual anterior cingulate cortex is noted to be caused by a dysfunctional effective connectivity from the pregenual anterior cingulate cortex to the dorsal anterior cingulate cortex, which improves and normalizes after real tDCS but not sham tDCS. In conclusion, OCF tDCS exerts its effect via activation of the descending pain inhibitory pathway and de-activation of the salience network, both of which are abnormal in fibromyalgia.

Repetitive Transcranial Direct Current Stimulation Induced Excitability Changes of Primary Visual Cortex and Visual Learning Effects-A Pilot Study.

PubMed

Sczesny-Kaiser, Matthias; Beckhaus, Katharina; Dinse, Hubert R; Schwenkreis, Peter; Tegenthoff, Martin; Höffken, Oliver

2016-01-01

Studies on noninvasive motor cortex stimulation and motor learning demonstrated cortical excitability as a marker for a learning effect. Transcranial direct current stimulation (tDCS) is a non-invasive tool to modulate cortical excitability. It is as yet unknown how tDCS-induced excitability changes and perceptual learning in visual cortex correlate. Our study aimed to examine the influence of tDCS on visual perceptual learning in healthy humans. Additionally, we measured excitability in primary visual cortex (V1). We hypothesized that anodal tDCS would improve and cathodal tDCS would have minor or no effects on visual learning. Anodal, cathodal or sham tDCS were applied over V1 in a randomized, double-blinded design over four consecutive days (n = 30). During 20 min of tDCS, subjects had to learn a visual orientation-discrimination task (ODT). Excitability parameters were measured by analyzing paired-stimulation behavior of visual-evoked potentials (ps-VEP) and by measuring phosphene thresholds (PTs) before and after the stimulation period of 4 days. Compared with sham-tDCS, anodal tDCS led to an improvement of visual discrimination learning (p < 0.003). We found reduced PTs and increased ps-VEP ratios indicating increased cortical excitability after anodal tDCS (PT: p = 0.002, ps-VEP: p = 0.003). Correlation analysis within the anodal tDCS group revealed no significant correlation between PTs and learning effect. For cathodal tDCS, no significant effects on learning or on excitability could be seen. Our results showed that anodal tDCS over V1 resulted in improved visual perceptual learning and increased cortical excitability. tDCS is a promising tool to alter V1 excitability and, hence, perceptual visual learning.

Safe Direct Current Stimulation to Expand Capabilities of Neural Prostheses

PubMed Central

Fridman, Gene Y.; Della Santina, Charles C.

2014-01-01

While effective in treating some neurological disorders, neuroelectric prostheses are fundamentally limited because they must employ charge-balanced stimuli to avoid evolution of irreversible electrochemical reactions and their byproducts at the interface between metal electrodes and body fluids. Charge-balancing is typically achieved by using brief biphasic alternating current (AC) pulses, which typically excite nearby neural tissues but cannot efficiently inhibit them. In contrast, direct current (DC) applied via a metal electrode in contact with body fluids can excite, inhibit and modulate sensitivity of neurons; however, DC stimulation is biologically unsafe because it violates “safe charge injection” limits that have long been considered unavoidable constraints. In this report, we describe the design and fabrication of a safe DC stimulator (SDCS) that overcomes this constraint. The SCDS drives DC ionic current into target tissue via salt-bridge micropipette electrodes by switching valves in phase with AC square waves applied to metal electrodes contained within the device. This approach achieves DC ionic flow through tissue while still adhering to charge-balancing constraints at each electrode-saline interface. We show the SDCS’s ability to both inhibit and excite neural activity to achieve improved dynamic range during prosthetic stimulation of the vestibular part of the inner ear in chinchillas. PMID:23476007

The Use of Non-invasive Brain Stimulation Techniques to Facilitate Recovery from Post-stroke Aphasia

PubMed Central

Marchina, Sarah; Wan, Catherine Y.

2011-01-01

Aphasia is a common symptom after left hemispheric stroke. Neuroimaging techniques over the last 10–15 years have described two general trends: Patients with small left hemisphere strokes tend to recruit perilesional areas, while patients with large left hemisphere lesions recruit mainly homotopic regions in the right hemisphere. Non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been employed to facilitate recovery by stimulating lesional and contralesional regions. The majority of these brain stimulation studies have attempted to block homotopic regions in the right posterior inferior frontal gyrus (IFG) to affect a presumed disinhibited right IFG (triangular portion). Other studies have used anodal or excitatory tDCS to stimulate the contralesional (right) fronto-temporal region or parts of the intact left IFG and perilesional regions to improve speech-motor output. It remains unclear whether the interhemispheric disinhibition model, which is the basis for motor cortex stimulation studies, also applies to the language system. Future studies could address a number of issues, including: the effect of lesion location on current density distribution, timing of the intervention with regard to stroke onset, whether brain stimulation should be combined with behavioral therapy, and whether multiple brain sites should be stimulated. A better understanding of the predictors of recovery from natural outcome studies would also help to inform study design, and the selection of clinically meaningful outcome measures in future studies. PMID:21842404

The perception of complex pitch in cochlear implants: A comparison of monopolar and tripolar stimulation.

PubMed

Fielden, Claire A; Kluk, Karolina; Boyle, Patrick J; McKay, Colette M

2015-10-01

Cochlear implant listeners typically perform poorly in tasks of complex pitch perception (e.g., musical pitch and voice pitch). One explanation is that wide current spread during implant activation creates channel interactions that may interfere with perception of temporal fundamental frequency information contained in the amplitude modulations within channels. Current focusing using a tripolar mode of stimulation has been proposed as a way of reducing channel interactions, minimising spread of excitation and potentially improving place and temporal pitch cues. The present study evaluated the effect of mode in a group of cochlear implant listeners on a pitch ranking task using male and female singing voices separated by either a half or a quarter octave. Results were variable across participants, but on average, pitch ranking was at chance level when the pitches were a quarter octave apart and improved when the difference was a half octave. No advantage was observed for tripolar over monopolar mode at either pitch interval, suggesting that previously published psychophysical advantages for focused modes may not translate into improvements in complex pitch ranking. Evaluation of the spectral centroid of the stimulation pattern, plus a lack of significant difference between male and female voices, suggested that participants may have had difficulty in accessing temporal pitch cues in either mode.

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.

Electrical Stimulation as a Means for Improving Vision.

PubMed

Sehic, Amer; Guo, Shuai; Cho, Kin-Sang; Corraya, Rima M; Chen, Dong F; Utheim, Tor P

2016-11-01

Evolving research has provided evidence that noninvasive electrical stimulation (ES) of the eye may be a promising therapy for either preserving or restoring vision in several retinal and optic nerve diseases. In this review, we focus on minimally invasive strategies for the delivery of ES and accordingly summarize the current literature on transcorneal, transorbital, and transpalpebral ES in both animal experiments and clinical studies. Various mechanisms are believed to underlie the effects of ES, including increased production of neurotrophic agents, improved chorioretinal blood circulation, and inhibition of proinflammatory cytokines. Different animal models have demonstrated favorable effects of ES on both the retina and the optic nerve. Promising effects of ES have also been demonstrated in clinical studies; however, all current studies have a lack of randomization and/or a control group (sham). There is thus a pressing need for a deeper understanding of the underlying mechanisms that govern clinical success and optimization of stimulation parameters in animal studies. In addition, such research should be followed by large, prospective, clinical studies to explore the full potential of ES. Through this review, we aim to provide insight to guide future research on ES as a potential therapy for improving vision. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

GEOS. User Tutorials

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

Fu, Pengchen; Settgast, Randolph R.; Johnson, Scott M.

2014-12-17

GEOS is a massively parallel, multi-physics simulation application utilizing high performance computing (HPC) to address subsurface reservoir stimulation activities with the goal of optimizing current operations and evaluating innovative stimulation methods. GEOS enables coupling of di erent solvers associated with the various physical processes occurring during reservoir stimulation in unique and sophisticated ways, adapted to various geologic settings, materials and stimulation methods. Developed at the Lawrence Livermore National Laboratory (LLNL) as a part of a Laboratory-Directed Research and Development (LDRD) Strategic Initiative (SI) project, GEOS represents the culmination of a multi-year ongoing code development and improvement e ort that hasmore » leveraged existing code capabilities and sta expertise to design new computational geosciences software.« less

Novel Neurostimulation of Autonomic Pelvic Nerves Overcomes Bladder-Sphincter Dyssynergia

PubMed Central

Peh, Wendy Yen Xian; Mogan, Roshini; Thow, Xin Yuan; Chua, Soo Min; Rusly, Astrid; Thakor, Nitish V.; Yen, Shih-Cheng

2018-01-01

The disruption of coordination between smooth muscle contraction in the bladder and the relaxation of the external urethral sphincter (EUS) striated muscle is a common issue in dysfunctional bladders. It is a significant challenge to overcome for neuromodulation approaches to restore bladder control. Bladder-sphincter dyssynergia leads to undesirably high bladder pressures, and poor voiding outcomes, which can pose life-threatening secondary complications. Mixed pelvic nerves are potential peripheral targets for stimulation to treat dysfunctional bladders, but typical electrical stimulation of pelvic nerves activates both the parasympathetic efferent pathway to excite the bladder, as well as the sensory afferent pathway that causes unwanted sphincter contractions. Thus, a novel pelvic nerve stimulation paradigm is required. In anesthetized female rats, we combined a low frequency (10 Hz) stimulation to evoke bladder contraction, and a more proximal 20 kHz stimulation of the pelvic nerve to block afferent activation, in order to produce micturition with reduced bladder-sphincter dyssynergia. Increasing the phase width of low frequency stimulation from 150 to 300 μs alone was able to improve voiding outcome significantly. However, low frequency stimulation of pelvic nerves alone evoked short latency (19.9–20.5 ms) dyssynergic EUS responses, which were abolished with a non-reversible proximal central pelvic nerve cut. We demonstrated that a proximal 20 kHz stimulation of pelvic nerves generated brief onset effects at lower current amplitudes, and was able to either partially or fully block the short latency EUS responses depending on the ratio of the blocking to stimulation current. Our results indicate that ratios >10 increased the efficacy of blocking EUS contractions. Importantly, we also demonstrated for the first time that this combined low and high frequency stimulation approach produced graded control of the bladder, while reversibly blocking afferent signals that elicited dyssynergic EUS contractions, thus improving voiding by 40.5 ± 12.3%. Our findings support advancing pelvic nerves as a suitable neuromodulation target for treating bladder dysfunction, and demonstrate the feasibility of an alternative method to non-reversible nerve transection and sub-optimal intermittent stimulation methods to reduce dyssynergia. PMID:29618971

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.

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.

Modulating behavioral inhibition by tDCS combined with cognitive training.

PubMed

Ditye, Thomas; Jacobson, Liron; Walsh, Vincent; Lavidor, Michal

2012-06-01

Cognitive training is an effective tool to improve a variety of cognitive functions, and a small number of studies have now shown that brain stimulation accompanying these training protocols can enhance their effects. In the domain of behavioral inhibition, little is known about how training can affect this skill. As for transcranial direct current stimulation (tDCS), it was previously found that stimulation over the right inferior frontal gyrus (rIFG) facilitates behavioral inhibition performance and modulates its electrophysiological correlates. This study aimed to investigate this behavioral facilitation in the context of a learning paradigm by giving tDCS over rIFG repetitively over four consecutive days of training on a behavioral inhibition task (stop signal task (SST)). Twenty-two participants took part; ten participants were assigned to receive anodal tDCS (1.5 mA, 15 min), 12 were assigned to receive training but not active stimulation. There was a significant effect of training on learning and performance in the SST, and the integration of the training and rIFG-tDCS produced a more linear learning slope. Better performance was also found in the active stimulation group. Our findings show that tDCS-combined cognitive training is an effective tool for improving the ability to inhibit responses. The current study could constitute a step toward the use of tDCS and cognitive training as a therapeutic tool for cognitive control impairments in conditions such as attention-deficit hyperactivity disorder (ADHD) or schizophrenia.

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.

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

Calculating the electric field in real human head by transcranial magnetic stimulation with shield plate

NASA Astrophysics Data System (ADS)

Lu, Mai; Ueno, Shoogo

2009-04-01

In this paper, we present a transcranial magnetic stimulation (TMS) system by incorporating a conductive shield plate. The magnetic field, induced current density, and electric field in a real human head were calculated by impedance method and the results were compared with TMS without shielding. Our results show that the field localization can be improved by introducing a conductive shield plate; the stimulation magnitude (depth) in the brain is reduced comparing with the TMS without shielding. The strong magnetic field near the TMS coil is difficult to be efficiently shielded by a thinner conductive shield plate.

Evaluation of focused multipolar stimulation for cochlear implants: a preclinical safety study

NASA Astrophysics Data System (ADS)

Shepherd, Robert K.; Wise, Andrew K.; Enke, Ya Lang; Carter, Paul M.; Fallon, James B.

2017-08-01

Objective. Cochlear implants (CIs) have a limited number of independent stimulation channels due to the highly conductive nature of the fluid-filled cochlea. Attempts to develop highly focused stimulation to improve speech perception in CI users includes the use of simultaneous stimulation via multiple current sources. Focused multipolar (FMP) stimulation is an example of this approach and has been shown to reduce interaction between stimulating channels. However, compared with conventional biphasic current pulses generated from a single current source, FMP is a complex stimulus that includes extended periods of stimulation before charge recovery is achieved, raising questions on whether chronic stimulation with this strategy is safe. The present study evaluated the long-term safety of intracochlear stimulation using FMP in a preclinical animal model of profound deafness. Approach. Six cats were bilaterally implanted with scala tympani electrode arrays two months after deafening, and received continuous unilateral FMP stimulation at levels that evoked a behavioural response for periods of up to 182 d. Electrode impedance, electrically-evoked compound action potentials (ECAPs) and auditory brainstem responses (EABRs) were monitored periodically over the course of the stimulation program from both the stimulated and contralateral control cochleae. On completion of the stimulation program cochleae were examined histologically and the electrode arrays were evaluated for evidence of platinum (Pt) corrosion. Main results. There was no significant difference in electrode impedance between control and chronically stimulated electrodes following long-term FMP stimulation. Moreover, there was no significant difference between ECAP and EABR thresholds evoked from control or stimulated cochleae at either the onset of stimulation or at completion of the stimulation program. Chronic FMP stimulation had no effect on spiral ganglion neuron (SGN) survival when compared with unstimulated control cochleae. Long-term implantation typically evoked a mild foreign body reaction proximal to the electrode array; however stimulated cochleae exhibited a small but statistically significant increase in the tissue response. Finally, there was no evidence of Pt corrosion following long-term FMP stimulation; stimulated electrodes exhibited the same surface features as the unstimulated control electrodes. Significance. Chronic intracochlear FMP stimulation at levels used in the present study did not adversely affect electrically-evoked neural thresholds or SGN survival but evoked a small, benign increase in inflammatory response compared to control ears. Moreover chronic FMP stimulation does not affect the surface of Pt electrodes at suprathreshold stimulus levels. These findings support the safe clinical application of an FMP stimulation strategy.

Enhanced Soft Tissue Attachment and Fixation Using a Mechanically-Stimulated Cytoselective Tissue-Specific ECM Coating

DTIC Science & Technology

2012-08-01

currently used for surgical reinforcement for tendon rotator cuff repair . All scaffolds in this study were seeded using this protocol. PLA fabric...extracellular matrix scaffolds for rotator cuff tendon repair . Biomechanical, biochemical, and cellular properties. J Bone Joint Surg Am 2006;88(12):2665-72...mechanical stimulation of a co-cultured biomaterial scaffold can improve/expedite healing of a tendon-to-bone interface for soft tissue repair . There

The Effect of a Transcranial Channel as a Skull/Brain Interface in High-Definition Transcranial Direct Current Stimulation—A Computational Study

NASA Astrophysics Data System (ADS)

Seo, Hyeon; Kim, Hyoung-Ihl; Jun, Sung Chan

2017-01-01

A transcranial channel is an interface between the skull and brain; it consists of a biocompatible and highly conductive material that helps convey the current induced by transcranial direct current stimulation (tDCS) to the target area. However, it has been proposed only conceptually, and there has been no concrete study of its efficacy. In this work, we conducted a computational investigation of this conceptual transcranial model with high-definition tDCS, inducing focalized neuromodulation to determine whether inclusion of a transcranial channel performs effectively. To do so, we constructed an anatomically realistic head model and compartmental pyramidal neuronal models. We analyzed membrane polarization by extracellular stimulation and found that the inclusion of a transcranial channel induced polarization at the target area 11 times greater than conventional HD-tDCS without the transcranial channel. Furthermore, the stimulation effect of the transcranial channel persisted up to approximately 80%, even when the stimulus electrodes were displaced approximately 5 mm from the target area. We investigated the efficacy of the transcranial channel and found that greatly improved stimulation intensity and focality may be achieved. Thus, the use of these channels may be promising for clinical treatment.

The Effects of Compensatory Auditory Stimulation and High-Definition Transcranial Direct Current Stimulation (HD-tDCS) on Tinnitus Perception - A Randomized Pilot Study.

PubMed

Henin, Simon; Fein, Dovid; Smouha, Eric; Parra, Lucas C

2016-01-01

Tinnitus correlates with elevated hearing thresholds and reduced cochlear compression. We hypothesized that reduced peripheral input leads to elevated neuronal gain resulting in the perception of a phantom sound. The purpose of this pilot study was to test whether compensating for this peripheral deficit could reduce the tinnitus percept acutely using customized auditory stimulation. To further enhance the effects of auditory stimulation, this intervention was paired with high-definition transcranial direct current stimulation (HD-tDCS). A randomized sham-controlled, single blind study was conducted in a clinical setting on adult participants with chronic tinnitus (n = 14). Compensatory auditory stimulation (CAS) and HD-tDCS were administered either individually or in combination in order to access the effects of both interventions on tinnitus perception. CAS consisted of sound exposure typical to daily living (20-minute sound-track of a TV show), which was adapted with compressive gain to compensate for deficits in each subject's individual audiograms. Minimum masking levels and the visual analog scale were used to assess the strength of the tinnitus percept immediately before and after the treatment intervention. CAS reduced minimum masking levels, and visual analog scale trended towards improvement. Effects of HD-tDCS could not be resolved with the current sample size. The results of this pilot study suggest that providing tailored auditory stimulation with frequency-specific gain and compression may alleviate tinnitus in a clinical population. Further experimentation with longer interventions is warranted in order to optimize effect sizes.

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.

Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

NASA Astrophysics Data System (ADS)

Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

2011-10-01

In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.

Enhancing social ability by stimulating right temporoparietal junction.

PubMed

Santiesteban, Idalmis; Banissy, Michael J; Catmur, Caroline; Bird, Geoffrey

2012-12-04

The temporoparietal junction (TPJ) is a key node within the "social brain". Several studies suggest that the TPJ controls representations of the self or another individual across a variety of low-level (agency discrimination, visual perspective taking, control of imitation) and high-level (mentalizing, empathy) sociocognitive processes. We explored whether sociocognitive abilities relying on on-line control of self and other representations could be modulated with transcranial direct current stimulation (tDCS) of TPJ. Participants received excitatory (anodal), inhibitory (cathodal), or sham stimulation before completing three sociocognitive tasks. Anodal stimulation improved the on-line control of self-other representations elicited by the imitation and perspective-taking tasks while not affecting attribution of mental states during a self-referential task devoid of such a requirement. Our findings demonstrate the efficacy of tDCS to improve social cognition and highlight the potential for tDCS to be used as a tool to aid self-other processing in clinical populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity.

PubMed

Ekelem, Andrew; Goldfarb, Michael

2018-01-01

Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common peroneal stimulation has only acute effects on suppressing extensor tone and aiding flexion. This preliminary data indicates that such supplemental stimulation may be used to improve the quality of movement provided by exoskeletons for persons with severe extensor spasticity in the lower limb.

Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

PubMed Central

Ekelem, Andrew; Goldfarb, Michael

2018-01-01

Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common peroneal stimulation has only acute effects on suppressing extensor tone and aiding flexion. This preliminary data indicates that such supplemental stimulation may be used to improve the quality of movement provided by exoskeletons for persons with severe extensor spasticity in the lower limb. PMID:29910710

Electrical stimulation in exercise training

NASA Technical Reports Server (NTRS)

Kroll, Walter

1994-01-01

Electrical stimulation has a long history of use in medicine dating back to 46 A.D. when the Roman physician Largus found the electrical discharge of torpedo fishes useful in the treatment of pain produced by headache and gout. A rival Greek physician, Dioscorides, discounted the value of the torpedo fish for headache relief but did recommend its use in the treatment of hemorrhoids. In 1745, the Leyden jar and various sized electrostatic generators were used to treat angina pectoris, epilepsy, hemiplegia, kidney stones, and sciatica. Benjamin Franklin used an electrical device to treat successfully a young woman suffering from convulsive fits. In the late 1800's battery powered hydroelectric baths were used to treat chronic inflammation of the uterus while electrified athletic supporters were advertised for the treatment of male problems. Fortunately, such an amusing early history of the simple beginnings of electrical stimulation did not prevent eventual development of a variety of useful therapeutic and rehabilitative applications of electrical stimulation. Over the centuries electrical stimulation has survived as a modality in the treatment of various medical disorders with its primary application being in the rehabilitation area. Recently, a surge of new interest in electrical stimulation has been kindled by the work of a Russian sport scientist who reported remarkable muscle strength and endurance improvements in elite athletes. Yakov Kots reported his research on electric stimulation and strength improvements in 1977 at a Canadian-Soviet Exchange Symposium held at Concordia University in Montreal. Since then an explosion of new studies has been seen in both sport science and in medicine. Based upon the reported works of Kots and the present surge of new investigations, one could be misled as to the origin of electrical stimulation as a technique to increase muscle strength. As a matter of fact, electric stimulation has been used as a technique to improve muscle strength for over a century. Bigelow reported in 1894, for example, the use of electrical stimulation on a young man for the purpose of increasing muscle strength. Employing a rapidly alternating sinusoidal induced current and a dynamometer for strength testing, Bigelow reported that the total lifting capacity of a patient increased from 4328 pounds to 4639 pounds after only 25 minutes of stimulation. In 1965, Massey et al. reported on the use of an Isotron electrical stimulator that emitted a high frequency current. Interestingly enough, the frequencies used by Massey et al. and the frequencies used by Bigelow in 1894 were in the same range of frequencies reported by Kots as being the most effective in strength development. It would seem the Russian secret of high frequency electrical stimulation for strength development, then, is not a modern development at all.

Restoring the encoding properties of a stochastic neuron model by an exogenous noise

PubMed Central

Paffi, Alessandra; Camera, Francesca; Apollonio, Francesca; d'Inzeo, Guglielmo; Liberti, Micaela

2015-01-01

Here we evaluate the possibility of improving the encoding properties of an impaired neuronal system by superimposing an exogenous noise to an external electric stimulation signal. The approach is based on the use of mathematical neuron models consisting of stochastic HH-like circuit, where the impairment of the endogenous presynaptic inputs is described as a subthreshold injected current and the exogenous stimulation signal is a sinusoidal voltage perturbation across the membrane. Our results indicate that a correlated Gaussian noise, added to the sinusoidal signal can significantly increase the encoding properties of the impaired system, through the Stochastic Resonance (SR) phenomenon. These results suggest that an exogenous noise, suitably tailored, could improve the efficacy of those stimulation techniques used in neuronal systems, where the presynaptic sensory neurons are impaired and have to be artificially bypassed. PMID:25999845

Transient interaction model of electromagnetic field generated by lightning current pulses and human body

NASA Astrophysics Data System (ADS)

Iváncsy, T.; Kiss, I.; Szücs, L.; Tamus, Z. Á.

2015-10-01

The lightning current generates time-varying magnetic field near the down- conductor and the down-conductors are mounted on the wall of the buildings where residential places might be situated. It is well known that the rapidly changing magnetic fields can generate dangerous eddy currents in the human body.The higher duration and gradient of the magnetic field can cause potentially life threatening cardiac stimulation. The coupling mechanism between the electromagnetic field and the human body is based on a well-known physical phenomena (e.g. Faradays law of induction). However, the calculation of the induced current is very complicated because the shape of the organs is complex and the determination of the material properties of living tissues is difficult, as well. Our previous study revealed that the cardiac stimulation is independent of the rising time of the lightning current and only the peak of the current counts. In this study, the authors introduce an improved model of the interaction of electromagnetic fields of lighting current near down-conductor and human body. Our previous models are based on the quasi stationer field calculations, the new improved model is a transient model. This is because the magnetic field around the down-conductor and in the human body can be determined more precisely, therefore the dangerous currents in the body can be estimated.

Poststimulation time interval-dependent effects of motor cortex anodal tDCS on reaction-time task performance.

PubMed

Molero-Chamizo, Andrés; Alameda Bailén, José R; Garrido Béjar, Tamara; García López, Macarena; Jaén Rodríguez, Inmaculada; Gutiérrez Lérida, Carolina; Pérez Panal, Silvia; González Ángel, Gloria; Lemus Corchero, Laura; Ruiz Vega, María J; Nitsche, Michael A; Rivera-Urbina, Guadalupe N

2018-02-01

Anodal transcranial direct current stimulation (tDCS) induces long-term potentiation-like plasticity, which is associated with long-lasting effects on different cognitive, emotional, and motor performances. Specifically, tDCS applied over the motor cortex is considered to improve reaction time in simple and complex tasks. The timing of tDCS relative to task performance could determine the efficacy of tDCS to modulate performance. The aim of this study was to compare the effects of a single session of anodal tDCS (1.5 mA, for 15 min) applied over the left primary motor cortex (M1) versus sham stimulation on performance of a go/no-go simple reaction-time task carried out at three different time points after tDCS-namely, 0, 30, or 60 min after stimulation. Performance zero min after anodal tDCS was improved during the whole course of the task. Performance 30 min after anodal tDCS was improved only in the last block of the reaction-time task. Performance 60 min after anodal tDCS was not significantly different throughout the entire task. These findings suggest that the motor cortex excitability changes induced by tDCS can improve motor responses, and these effects critically depend on the time interval between stimulation and task performance.

A Systematic Review and Meta-Analysis of the Effects of Transcranial Direct Current Stimulation (tDCS) Over the Dorsolateral Prefrontal Cortex in Healthy and Neuropsychiatric Samples: Influence of Stimulation Parameters.

PubMed

Dedoncker, Josefien; Brunoni, Andre R; Baeken, Chris; Vanderhasselt, Marie-Anne

2016-01-01

Research into the effects of transcranial direct current stimulation of the dorsolateral prefrontal cortex on cognitive functioning is increasing rapidly. However, methodological heterogeneity in prefrontal tDCS research is also increasing, particularly in technical stimulation parameters that might influence tDCS effects. To systematically examine the influence of technical stimulation parameters on DLPFC-tDCS effects. We performed a systematic review and meta-analysis of tDCS studies targeting the DLPFC published from the first data available to February 2016. Only single-session, sham-controlled, within-subject studies reporting the effects of tDCS on cognition in healthy controls and neuropsychiatric patients were included. Evaluation of 61 studies showed that after single-session a-tDCS, but not c-tDCS, participants responded faster and more accurately on cognitive tasks. Sub-analyses specified that following a-tDCS, healthy subjects responded faster, while neuropsychiatric patients responded more accurately. Importantly, different stimulation parameters affected a-tDCS effects, but not c-tDCS effects, on accuracy in healthy samples vs. increased current density and density charge resulted in improved accuracy in healthy samples, most prominently in females; for neuropsychiatric patients, task performance during a-tDCS resulted in stronger increases in accuracy rates compared to task performance following a-tDCS. Healthy participants respond faster, but not more accurate on cognitive tasks after a-tDCS. However, increasing the current density and/or charge might be able to enhance response accuracy, particularly in females. In contrast, online task performance leads to greater increases in response accuracy than offline task performance in neuropsychiatric patients. Possible implications and practical recommendations are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of transcranial direct current stimulation over the supplementary motor area body weight-supported treadmill gait training in hemiparetic patients after stroke.

PubMed

Manji, Atsushi; Amimoto, Kazu; Matsuda, Tadamitsu; Wada, Yoshiaki; Inaba, Akira; Ko, Sangkyun

2018-01-01

Transcranial direct current stimulation (tDCS) is used in a variety of disorders after stroke including upper limb motor dysfunctions, hemispatial neglect, aphasia, and apraxia, and its effectiveness has been demonstrated. Although gait ability is important for daily living, there were few reports of the use of tDCS to improve balance and gait ability. The supplementary motor area (SMA) was reported to play a potentially important role in balance recovery after stroke. We aimed to investigate the effect of combined therapy body weight-supported treadmill training (BWSTT) and tDCS on gait function recovery of stroke patients. Thirty stroke inpatients participated in this study. The two BWSTT periods of 1weeks each, with real tDCS (anode: front of Cz, cathode: inion, 1mA, 20min) on SMA and sham stimulation, were randomized in a double-blind crossover design. We measured the time required for the 10m Walk Test (10MWT) and Timed Up and Go (TUG) test before and after each period. We found that the real tDCS with BWSTT significantly improved gait speed (10MWT) and applicative walking ability (TUG), compared with BWSTT+sham stimulation periods (p<0.05). Our findings demonstrated the feasibility and efficacy of tDCS in gait training after stroke. The facilitative effects of tDCS on SMA possibly improved postural control during BWSTT. The results indicated the implications for the use of tDCS in balance and gait training rehabilitation after stroke. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of prefrontal tDCS on executive function: Methodological considerations revealed by meta-analysis.

PubMed

Imburgio, Michael J; Orr, Joseph M

2018-05-01

A meta-analysis of studies using single-session transcranial direct current stimulation (tDCS) to target the dorsolateral prefrontal cortex (DLPFC) was undertaken to examine the effect of stimulation on executive function (EF) in healthy samples. 27 studies were included in analyses, yielding 71 effect sizes. The most relevant measure for each task was determined a priori and used to calculate Hedge's g. Methodological characteristics of each study were examined individually as potential moderators of effect size. Stimulation effects on three domains of EF (inhibition of prepotent responses, mental set shifting, and information updating and monitoring) were analyzed separately. In line with previous work, the current study found no significant effect of anodal unilateral tDCS, cathodal unilateral tDCS, or bilateral tDCS on EF. Further moderator and subgroup analyses were only carried out for anodal unilateral montages due to the small number of studies using other montages. Subgroup analyses revealed a significant effect of anodal unilateral tDCS on updating tasks, but not on inhibition or set-shifting tasks. Cathode location significantly moderated the effect of anodal unilateral tDCS. Extracranial cathodes yielded a significant effect on EF while cranial cathodes yielded no effect. Anode size also significantly moderated effect of anodal unilateral tDCS, with smaller anodes being more effective than larger anodes. In summary, anodal DLPFC stimulation is more effective at improving updating ability than inhibition and set-shifting ability, but anodal stimulation can significantly improve general executive function when extracranial cathodes or small anodes are used. Future meta-analyses may examine how stimulation's effects on specific behavioral tasks, rather than broader domains, might be affected by methodological moderators. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oscillatory Reinstatement Enhances Declarative Memory.

PubMed

Javadi, Amir-Homayoun; Glen, James C; Halkiopoulos, Sara; Schulz, Mei; Spiers, Hugo J

2017-10-11

Declarative memory recall is thought to involve the reinstatement of neural activity patterns that occurred previously during encoding. Consistent with this view, greater similarity between patterns of activity recorded during encoding and retrieval has been found to predict better memory performance in a number of studies. Recent models have argued that neural oscillations may be crucial to reinstatement for successful memory retrieval. However, to date, no causal evidence has been provided to support this theory, nor has the impact of oscillatory electrical brain stimulation during encoding and retrieval been assessed. To explore this we used transcranial alternating current stimulation over the left dorsolateral prefrontal cortex of human participants [ n = 70, 45 females; age mean (SD) = 22.12 (2.16)] during a declarative memory task. Participants received either the same frequency during encoding and retrieval (60-60 or 90-90 Hz) or different frequencies (60-90 or 90-60 Hz). When frequencies matched there was a significant memory improvement (at both 60 and 90 Hz) relative to sham stimulation. No improvement occurred when frequencies mismatched. Our results provide support for the role of oscillatory reinstatement in memory retrieval. SIGNIFICANCE STATEMENT Recent neurobiological models of memory have argued that large-scale neural oscillations are reinstated to support successful memory retrieval. Here we used transcranial alternating current stimulation (tACS) to test these models. tACS has recently been shown to induce neural oscillations at the frequency stimulated. We stimulated over the left dorsolateral prefrontal cortex during a declarative memory task involving learning a set of words. We found that tACS applied at the same frequency during encoding and retrieval enhances memory. We also find no difference between the two applied frequencies. Thus our results are consistent with the proposal that reinstatement of neural oscillations during retrieval supports successful memory retrieval. Copyright © 2017 Javadi et al.

Effects of transcranial direct current stimulation on the auditory mismatch negativity response and working memory performance in schizophrenia: a pilot study.

PubMed

Impey, Danielle; Baddeley, Ashley; Nelson, Renee; Labelle, Alain; Knott, Verner

2017-11-01

Cognitive impairment has been proposed to be the core feature of schizophrenia (Sz). Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation which can improve cognitive function in healthy participants and in psychiatric patients with cognitive deficits. tDCS has been shown to improve cognition and hallucination symptoms in Sz, a disorder also associated with marked sensory processing deficits. Recent findings in healthy controls demonstrate that anodal tDCS increases auditory deviance detection, as measured by the brain-based event-related potential, mismatch negativity (MMN), which is a putative biomarker of Sz that has been proposed as a target for treatment of Sz cognition. This pilot study conducted a randomized, double-blind assessment of the effects of pre- and post-tDCS on MMN-indexed auditory discrimination in 12 Sz patients, moderated by auditory hallucination (AH) presence, as well as working memory performance. Assessments were conducted in three sessions involving temporal and frontal lobe anodal stimulation (to transiently excite local brain activity), and one control session involving 'sham' stimulation (meaning with the device turned off, i.e., no stimulation). Results demonstrated a trend for pitch MMN amplitude to increase with anodal temporal tDCS, which was significant in a subgroup of Sz individuals with AHs. Anodal frontal tDCS significantly increased WM performance on the 2-back task, which was found to positively correlate with MMN-tDCS effects. The findings contribute to our understanding of tDCS effects for sensory processing deficits and working memory performance in Sz and may have implications for psychiatric disorders with sensory deficits.

Trends in Timber Use and Product Recovery in New York

Treesearch

Eric H. Wharton; Thomas W. Birch; Thomas W. Birch

1999-01-01

High demand for a variety of timber products from New York's forests has stimulated increased timber utilization and product recovery. Utilization studies in New York suggest that the recovery of timber has improved over the years. Although current methods of multiproduct harvesting have improved recovery of residual material, an estimated 38.6 million cubic feet...

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

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.

Neural substrates underlying stimulation-enhanced motor skill learning after stroke

PubMed Central

Lefebvre, Stéphanie; Dricot, Laurence; Laloux, Patrice; Gradkowski, Wojciech; Desfontaines, Philippe; Evrard, Frédéric; Peeters, André; Jamart, Jacques

2015-01-01

Motor skill learning is one of the key components of motor function recovery after stroke, especially recovery driven by neurorehabilitation. Transcranial direct current stimulation can enhance neurorehabilitation and motor skill learning in stroke patients. However, the neural mechanisms underlying the retention of stimulation-enhanced motor skill learning involving a paretic upper limb have not been resolved. These neural substrates were explored by means of functional magnetic resonance imaging. Nineteen chronic hemiparetic stroke patients participated in a double-blind, cross-over randomized, sham-controlled experiment with two series. Each series consisted of two sessions: (i) an intervention session during which dual transcranial direct current stimulation or sham was applied during motor skill learning with the paretic upper limb; and (ii) an imaging session 1 week later, during which the patients performed the learned motor skill. The motor skill learning task, called the ‘circuit game’, involves a speed/accuracy trade-off and consists of moving a pointer controlled by a computer mouse along a complex circuit as quickly and accurately as possible. Relative to the sham series, dual transcranial direct current stimulation applied bilaterally over the primary motor cortex during motor skill learning with the paretic upper limb resulted in (i) enhanced online motor skill learning; (ii) enhanced 1-week retention; and (iii) superior transfer of performance improvement to an untrained task. The 1-week retention’s enhancement driven by the intervention was associated with a trend towards normalization of the brain activation pattern during performance of the learned motor skill relative to the sham series. A similar trend towards normalization relative to sham was observed during performance of a simple, untrained task without a speed/accuracy constraint, despite a lack of behavioural difference between the dual transcranial direct current stimulation and sham series. Finally, dual transcranial direct current stimulation applied during the first session enhanced continued learning with the paretic limb 1 week later, relative to the sham series. This lasting behavioural enhancement was associated with more efficient recruitment of the motor skill learning network, that is, focused activation on the motor-premotor areas in the damaged hemisphere, especially on the dorsal premotor cortex. Dual transcranial direct current stimulation applied during motor skill learning with a paretic upper limb resulted in prolonged shaping of brain activation, which supported behavioural enhancements in stroke patients. PMID:25488186

Technological Advances In The Surgical Treatment Of Movement Disorders

PubMed Central

Gross, Robert E.; McDougal, Margaret E.

2013-01-01

Technological innovations have driven the advancement of the surgical treatment of movement disorders, from the invention of the stereotactic frame to the adaptation of deep brain stimulation (DBS). Along these lines, this review will describe recent advances in getting neuromodulation modalities, including DBS, to the target; and in the delivery of therapy at the target. Recent radiological advances are altering the way that DBS leads are targeted and inserted, by refining the ability to visualize the subcortical targets using high-field strength MRI and other innovations such as diffusion tensor imaging, and the development of novel targeting devices enabling purely anatomical implantations without the need for neurophysiological monitoring. New portable CT scanners also are facilitating lead implantation without monitoring as well as improving radiological verification of DBS lead location. Advances in neurophysiological mapping include efforts to develop automatic target verification algorithms, and probabilistic maps to guide target selection. The delivery of therapy at the target is being improved by the development of the next generation of internal pulse generators (IPGs). These include constant current devices that mitigate the variability introduced by impedance changes of the stimulated tissue, and in the near future, devices that deliver novel stimulation patterns with improved efficiency. Closed-loop adaptive IPGs are being tested, which may tailor stimulation to ongoing changes in the nervous system reflected in Œbiomarkers1 continuously recorded by the devices. Finer grained DBS leads, in conjunction with new IPGs and advanced programming tools, may offer improved outcomes via Œcurrent steering1 algorithms. Finally, even thermocoagulation - essentially replaced by DBS - is being advanced by new Œminimally-invasive1 approaches that may improve this therapy for selected patients in whom it may be preferred. Functional neurosurgery has a history of being driven by technological innovation, a tradition that continues into its future. PMID:23812894

Consensus: “Can tDCS and TMS enhance motor learning and memory formation?”

PubMed Central

Reis, Janine; Robertson, Edwin; Krakauer, John W.; Rothwell, John; Marshall, Lisa; Gerloff, Christian; Wassermann, Eric; Pascual-Leone, Alvaro; Hummel, Friedhelm; Celnik, Pablo A.; Classen, Joseph; Floel, Agnes; Ziemann, Ulf; Paulus, Walter; Siebner, Hartwig R.; Born, Jan; Cohen, Leonardo G.

2009-01-01

Noninvasive brain stimulation has developed as a promising tool for cognitive neuroscientists. Transcranial magnetic (TMS) and direct current (tDCS) stimulation allow researchers to purposefully enhance or decrease excitability in focal areas of the brain. The purpose of this paper is to review information on the use of TMS and tDCS as research tools to facilitate motor memory formation, motor performance and motor learning in healthy volunteers. Studies implemented so far have mostly focused on the ability of TMS and tDCS to elicit relatively short lasting motor improvements and the mechanisms underlying these changes have been only partially investigated. Despite limitations including the scarcity of data, work that has been already accomplished raises the exciting hypothesis that currently available noninvasive transcranial stimulation techniques could modulate motor learning and memory formation in healthy humans and potentially in patients with neurological and psychiatric disorders. PMID:19802336

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.

A Wearable EEG-HEG-HRV Multimodal System With Simultaneous Monitoring of tES for Mental Health Management.

PubMed

Ha, Unsoo; Lee, Yongsu; Kim, Hyunki; Roh, Taehwan; Bae, Joonsung; Kim, Changhyeon; Yoo, Hoi-Jun

2015-12-01

A multimodal mental management system in the shape of the wearable headband and earplugs is proposed to monitor electroencephalography (EEG), hemoencephalography (HEG) and heart rate variability (HRV) for accurate mental health monitoring. It enables simultaneous transcranial electrical stimulation (tES) together with real-time monitoring. The total weight of the proposed system is less than 200 g. The multi-loop low-noise amplifier (MLLNA) achieves over 130 dB CMRR for EEG sensing and the capacitive correlated-double sampling transimpedance amplifier (CCTIA) has low-noise characteristics for HEG and HRV sensing. Measured three-physiology domains such as neural, vascular and autonomic domain signals are combined with canonical correlation analysis (CCA) and temporal kernel canonical correlation analysis (tkCCA) algorithm to find the neural-vascular-autonomic coupling. It supports highly accurate classification with the 19% maximum improvement with multimodal monitoring. For the multi-channel stimulation functionality, after-effects maximization monitoring and sympathetic nerve disorder monitoring, the stimulator is designed as reconfigurable. The 3.37 × 2.25 mm(2) chip has 2-channel EEG sensor front-end, 2-channel NIRS sensor front-end, NIRS current driver to drive dual-wavelength VCSEL and 6-b DAC current source for tES mode. It dissipates 24 mW with 2 mA stimulation current and 5 mA NIRS driver current.

Systematic Review of Parameters of Stimulation, Clinical Trial Design Characteristics, and Motor Outcomes in Non-Invasive Brain Stimulation in Stroke

PubMed Central

Adeyemo, Bamidele O.; Simis, Marcel; Macea, Debora Duarte; Fregni, Felipe

2012-01-01

Introduction/Objectives: Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation are two powerful non-invasive neuromodulatory therapies that have the potential to alter and evaluate the integrity of the corticospinal tract. Moreover, recent evidence has shown that brain stimulation might be beneficial in stroke recovery. Therefore, investigating and investing in innovative therapies that may improve neurorehabilitative stroke recovery are next steps in research and development. Participants/Materials and Methods: This article presents an up-to-date systematic review of the treatment effects of rTMS and tDCS on motor function. A literary search was conducted, utilizing search terms “stroke” and “transcranial stimulation.” Items were excluded if they failed to: (1) include stroke patients, (2) study motor outcomes, or (3) include rTMS/tDCS as treatments. Other exclusions included: (1) reviews, editorials, and letters, (2) animal or pediatric populations, (3) case reports or sample sizes ≤2 patients, and (4) primary outcomes of dysphagia, dysarthria, neglect, or swallowing. Results: Investigation of PubMed English Database prior to 01/01/2012 produced 695 applicable results. Studies were excluded based on the aforementioned criteria, resulting in 50 remaining studies. They included 1314 participants (1282 stroke patients and 32 healthy subjects) evaluated by motor function pre- and post-tDCS or rTMS. Heterogeneity among studies’ motor assessments was high and could not be accounted for by individual comparison. Pooled effect sizes for the impact of post-treatment improvement revealed consistently demonstrable improvements after tDCS and rTMS therapeutic stimulation. Most studies provided limited follow-up for long-term effects. Conclusion: It is apparent from the available studies that non-invasive stimulation may enhance motor recovery and may lead to clinically meaningful functional improvements in the stroke population. Only mild to no adverse events have been reported. Though results have been positive results, the large heterogeneity across articles precludes firm conclusions. PMID:23162477

Reducing Current Spread using Current Focusing in Cochlear Implant Users

PubMed Central

Landsberger, David M.; Padilla, Monica; Srinivasan, Arthi G.

2012-01-01

Cochlear implant performance in difficult listening situations is limited by channel interactions. It is known that partial tripolar (PTP) stimulation reduces the spread of excitation (SOE). However, the greater the degree of current focusing, the greater the absolute current required to maintain a fixed loudness. As current increases, so does SOE. In experiment 1, the SOE for equally loud stimuli with different degrees of current focusing is measured via a forward-masking procedure. Results suggest that at a fixed loudness, some but not all patients have a reduced SOE with PTP stimulation. Therefore, it seems likely that a PTP speech processing strategy could improve spectral resolution for only those patients with a reduced SOE. In experiment 2, the ability to discriminate different levels of current focusing was measured. In experiment 3, patients subjectively scaled verbal descriptors of stimuli of various levels of current focusing. Both discrimination and scaling of verbal descriptors correlated well with SOE reduction, suggesting that either technique have the potential to be used clinically to quickly predict which patients would receive benefit from a current focusing strategy. PMID:22230370

Effects of Stand and Step Training with Epidural Stimulation on Motor Function for Standing in Chronic Complete Paraplegics

PubMed Central

Rejc, Enrico; Angeli, Claudia A.; Bryant, Nicole

2017-01-01

Abstract Individuals affected by motor complete spinal cord injury are unable to stand, walk, or move their lower limbs voluntarily; this diagnosis normally implies severe limitations for functional recovery. We have recently shown that the appropriate selection of epidural stimulation parameters was critical to promoting full-body, weight-bearing standing with independent knee extension in four individuals with chronic clinically complete paralysis. In the current study, we examined the effects of stand training and subsequent step training with epidural stimulation on motor function for standing in the same four individuals. After stand training, the ability to stand improved to different extents in the four participants. Step training performed afterwards substantially impaired standing ability in three of the four individuals. Improved standing ability generally coincided with continuous electromyography (EMG) patterns with constant levels of ground reaction forces. Conversely, poorer standing ability was associated with more variable EMG patterns that alternated EMG bursts and longer periods of negligible activity in most of the muscles. Stand and step training also differentially affected the evoked potentials amplitude modulation induced by sitting-to-standing transition. Finally, stand and step training with epidural stimulation were not sufficient to improve motor function for standing without stimulation. These findings show that the spinal circuitry of motor complete paraplegics can generate motor patterns effective for standing in response to task-specific training with optimized stimulation parameters. Conversely, step training can lead to neural adaptations resulting in impaired motor function for standing. PMID:27566051

Effects of cerebellar neuromodulation in movement disorders: A systematic review.

PubMed

França, Carina; de Andrade, Daniel Ciampi; Teixeira, Manoel Jacobsen; Galhardoni, Ricardo; Silva, Valquiria; Barbosa, Egberto Reis; Cury, Rubens Gisbert

The cerebellum is involved in the pathophysiology of many movement disorders and its importance in the field of neuromodulation is growing. To review the current evidence for cerebellar modulation in movement disorders and its safety profile. Eligible studies were identified after a systematic literature review of the effects of cerebellar modulation in cerebellar ataxia, Parkinson's disease (PD), essential tremor (ET), dystonia and progressive supranuclear palsy (PSP). Neuromodulation techniques included transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS). The changes in motor scores and the incidence of adverse events after the stimulation were reviewed. Thirty-four studies were included in the systematic review, comprising 431 patients. The evaluation after stimulation ranged from immediately after to 12 months after. Neuromodulation techniques improved cerebellar ataxia due to vascular or degenerative etiologies (TMS, tDCS and DBS), dyskinesias in PD patients (TMS), gross upper limb movement in PD patients (tDCS), tremor in ET (TMS and tDCS), cervical dystonia (TMS and tDCS) and dysarthria in PSP patients (TMS). All the neuromodulation techniques were safe, since only three studies reported the existence of side effects (slight headache after TMS, local skin erythema after tDCS and infectious complication after DBS). Eleven studies did not mention if adverse events occurred. Cerebellar modulation can improve specific symptoms in some movement disorders and is a safe and well-tolerated procedure. Further studies are needed to lay the groundwork for new researches in this promising target. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Therapeutic intraspinal microstimulation improves forelimb function after cervical contusion injury

NASA Astrophysics Data System (ADS)

Kasten, M. R.; Sunshine, M. D.; Secrist, E. S.; Horner, P. J.; Moritz, C. T.

2013-08-01

Objective. Intraspinal microstimulation (ISMS) is a promising method for activating the spinal cord distal to an injury. The objectives of this study were to examine the ability of chronically implanted stimulating wires within the cervical spinal cord to (1) directly produce forelimb movements, and (2) assess whether ISMS stimulation could improve subsequent volitional control of paretic extremities following injury. Approach. We developed a technique for implanting intraspinal stimulating electrodes within the cervical spinal cord segments C6-T1 of Long-Evans rats. Beginning 4 weeks after a severe cervical contusion injury at C4-C5, animals in the treatment condition received therapeutic ISMS 7 hours/day, 5 days/week for the following 12 weeks. Main results. Over 12 weeks of therapeutic ISMS, stimulus-evoked forelimb movements were relatively stable. We also explored whether therapeutic ISMS promoted recovery of forelimb reaching movements. Animals receiving daily therapeutic ISMS performed significantly better than unstimulated animals during behavioural tests conducted without stimulation. Quantitative video analysis of forelimb movements showed that stimulated animals performed better in the movements reinforced by stimulation, including extending the elbow to advance the forelimb and opening the digits. While threshold current to elicit forelimb movement gradually increased over time, no differences were observed between chronically stimulated and unstimulated electrodes suggesting that no additional tissue damage was produced by the electrical stimulation. Significance. The results indicate that therapeutic intraspinal stimulation delivered via chronic microwire implants within the cervical spinal cord confers benefits extending beyond the period of stimulation, suggesting future strategies for neural devices to promote sustained recovery after injury.

Therapeutic intraspinal microstimulation improves forelimb function after cervical contusion injury

PubMed Central

Kasten, M.R.; Sunshine, M.D.; Secrist, E.S.; Horner, P.J.; Moritz, C.T.

2013-01-01

Objective Intraspinal microstimulation (ISMS) is a promising method for activating the spinal cord distal to an injury. The objectives of this study were to examine the ability of chronically implanted stimulating wires within the cervical spinal cord to (1) directly produce forelimb movements, and (2) assess whether ISMS stimulation improved subsequent volitional control of paretic extremities following injury. Approach We developed a technique for implanting intraspinal stimulating electrodes within the cervical spinal cord segments C6-T1 of Long-Evans rats. Beginning 4 weeks after a severe cervical contusion injury at C4–C5, animals in the treatment condition received therapeutic ISMS 7 hours/day, 5 days/week for the following 12 weeks. Main Results Over 12 weeks of therapeutic ISMS, stimulus-evoked forelimb movements were relatively stable. We also explored whether therapeutic ISMS promotes recovery of forelimb reaching movements. Animals receiving daily therapeutic ISMS performed significantly better than unstimulated animals during behavioral tests conducted without stimulation. Quantitative video analysis of forelimb movements showed that stimulated animals performed better in the movements reinforced by stimulation, including extending the elbow to advance the forelimb and opening the digits. While threshold current to elicit forelimb movement gradually increased over time, no differences were observed between chronically stimulated and unstimulated electrodes suggesting that no additional tissue damage was produced by the electrical stimulation. Significance The results indicate that therapeutic intraspinal stimulation delivered via chronic microwire implants within the cervical spinal cord confers benefits extending beyond the period of stimulation, suggesting future strategies for neural devices to promote sustained recovery after injury. PMID:23715242

Effects of varying subthalamic nucleus stimulation on apraxia of lid opening in Parkinson's disease.

PubMed

Tommasi, Giorgio; Krack, Paul; Fraix, Valérie; Pollak, Pierre

2012-09-01

Apraxia of lid opening (ALO) is a non-paralytic inability to open the eyes or sustain lid elevation at will. The exact pathophysiological mechanisms underlying the syndrome are still unknown. ALO has been reported in patients with Parkinson's disease (PD) after subthalamic nucleus (STN) deep brain stimulation (DBS), suggesting a possible involvement of the basal ganglia. We aimed to assess the effects of varying STN stimulation voltage on ALO in PD patients. Seven out of 14 PD patients with bilateral STN stimulation consecutively seen in our centre presented with ALO. We progressively increased voltage on each STN, using either 130 Hz (high-frequency stimulation, HFS) or 2 or 3 Hz (low-frequency stimulation, LFS). In five patients, HFS induced ALO time-locked to stimulation in 7 out of 10 STNs at a voltage higher than that used for chronic stimulation. LFS induced myoclonus in the pretarsal orbicularis oculi muscle (pOOm) with a rhythm synchronous to the frequency. In the other two patients with ALO already present at the time of the study, HFS improved ALO in 3 out of 4 STNs. ALO recurred within minutes of stimulation arrest. Our findings show that STN-DBS can have opposite effects on ALO. On the one hand, ALO is thought to be a corticobulbar side effect due to lateral current spreading from the STN, in which case it is necessary to use voltages below the ALO-inducing threshold. On the other hand, ALO may be considered a form of off-phase focal dystonia possibly improved by increasing the stimulation voltages.

3D finite element modeling of epiretinal stimulation: Impact of prosthetic electrode size and distance from the retina.

PubMed

Sui, Xiaohong; Huang, Yu; Feng, Fuchen; Huang, Chenhui; Chan, Leanne Lai Hang; Wang, Guoxing

2015-05-01

A novel 3-dimensional (3D) finite element model was established to systematically investigate the impact of the diameter (Φ) of disc electrodes and the electrode-to-retina distance on the effectiveness of stimulation. The 3D finite element model was established based on a disc platinum stimulating electrode and a 6-layered retinal structure. The ground electrode was placed in the extraocular space in direct attachment with sclera and treated as a distant return electrode. An established criterion of electric-field strength of 1000 Vm-1 was adopted as the activation threshold for RGCs. The threshold current (TC) increased linearly with increasing Φ and electrode-to-retina distance and remained almost unchanged with further increases in diameter. However, the threshold charge density (TCD) increased dramatically with decreasing electrode diameter. TCD exceeded the electrode safety limit for an electrode diameter of 50 µm at an electrode-to-retina distance of 50 to 200 μm. The electric field distributions illustrated that smaller electrode diameters and shorter electrode-to-retina distances were preferred due to more localized excitation of RGC area under stimulation of different threshold currents in terms of varied electrode size and electrode-to-retina distances. Under the condition of same-amplitude current stimulation, a large electrode exhibited an improved potential spatial selectivity at large electrode-to-retina distances. Modeling results were consistent with those reported in animal electrophysiological experiments and clinical trials, validating the 3D finite element model of epiretinal stimulation. The computational model proved to be useful in optimizing the design of an epiretinal stimulating electrode for prosthesis.

Improving neurovascular outcomes with bilateral forepaw stimulation in a rat photothrombotic ischemic stroke model

PubMed Central

Liao, Lun-De; Bandla, Aishwarya; Ling, Ji Min; Liu, Yu-Hang; Kuo, Li-Wei; Chen, You-Yin; King, Nicolas KK; Lai, Hsin-Yi; Lin, Yan-Ren; Thakor, Nitish V.

2014-01-01

Abstract. Restoring perfusion to the penumbra during the hyperacute phase of ischemic stroke is a key goal of neuroprotection. Thrombolysis is currently the only approved treatment for ischemic stroke. However, its use is limited by the narrow therapeutic window and side effect of bleeding. Therefore, other interventions are desired that could potentially increase the perfusion of the penumbra. Here, we hypothesized that bilateral peripheral electrical stimulation will improve cerebral perfusion and restore cortical neurovascular response. We assess the outcomes of bilateral forepaw electrical stimulation at intensities of 2 and 4 mA, administered either unilaterally or bilaterally. We developed a combined electrocorticogram (ECoG)-functional photoacoustic microscopy (fPAM) system to evaluate the relative changes in cerebral hemodynamic function and electrophysiologic response to acute, focal stroke. The fPAM system is used for cerebral blood volume (CBV) and hemoglobin oxygen saturation (SO2) and the ECoG for neural activity, namely somatosensory-evoked potential (SSEP), interhemispheric coherence, and alpha-delta ratio (ADR) in response to forepaw stimulation. Our results confirmed the neuroprotective effect of bilateral forepaw stimulation at 2 mA as indicated by the 82% recovery of ADR and 95% improvement in perfusion into the region of penumbra. This experimental model can be used to study other potential interventions such as therapeutic hypertension and hypercarbia. PMID:26157965

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.

Restoration of bladder function in spastic neuropathic bladder using sacral deafferentation and different techniques of neurostimulation.

PubMed

Schumacher, S; Bross, S; Scheepe, J R; Alken, P; Jünemann, K P

1999-01-01

Conventional sacral anterior root stimulation (SARS) results in simultaneous activation of both the detrusor muscle and the external urethral sphincter. We evaluated the possibilities of different neurostimulation techniques to overcome stimulation induced detrusor-sphincter-dyssynergia and to achieve a physiological voiding. The literature was reviewed on different techniques of sacral anterior root stimulation of the bladder and the significance of posterior rhizotomy in patients with supraconal spinal cord injury suffering from the loss of voluntary bladder control, detrusor hyperreflexia and sphincter spasm. The achievement of selective detrusor activation would improve current sacral neurostimulation of the bladder, including the principle of "poststimulus voiding". This is possible with the application of selective neurostimulation in techniques of anodal block, high frequency block, depolarizing prepulses and cold block. Nowadays, sacral deafferentation is a standard therapy in combination with neurostimulation of the bladder because in conclusion advantages of complete rhizotomy predominate. The combination of sacral anterior root stimulation and sacral deafferentation is a successful procedure for restoration of bladder function in patients with supraconal spinal cord injury. Anodal block technique and cryotechnique are excellent methods for selective bladder activation to avoid detrusor-sphincter-dyssynergia and thus improve stimulation induced voiding.

Differential effects of 10-Hz and 40-Hz transcranial alternating current stimulation (tACS) on endogenous versus exogenous attention.

PubMed

Hopfinger, Joseph B; Parsons, Jonathan; Fröhlich, Flavio

2017-04-01

Previous electrophysiological studies implicate both alpha (8-12 Hz) and gamma (>30 Hz) neural oscillations in the mechanisms of selective attention. Here, participants preformed two separate visual attention tasks, one endogenous and one exogenous, while transcranial alternating current stimulation (tACS), at 10 Hz, 40 Hz, or sham, was applied to the right parietal lobe. Our results provide new evidence for the roles of gamma and alpha oscillations in voluntary versus involuntary shifts of attention. Gamma (40 Hz) stimulation resulted in improved disengagement from invalidly cued targets in the endogenous attention task, whereas alpha stimulation (10 Hz) had no effect on endogenous attention, but increased the exogenous cuing effect. These findings agree with previous studies suggesting that right inferior parietal regions may be especially important for the disengagement of attention, and go further to provide details about the specific type of oscillatory neural activity within that brain region that is differentially involved in endogenous versus exogenous attention. Our results also have potential implications for the plasticity and training of attention systems.

New directions in the rational design of electrical and magnetic seizure therapies: individualized Low Amplitude Seizure Therapy (iLAST) and Magnetic Seizure Therapy (MST).

PubMed

Radman, Thomas; Lisanby, Sarah H

2017-04-01

Electroconvulsive therapy remains a key treatment option for severe cases of depression, but undesirable side-effects continue to limit its use. Innovations in the design of novel seizure therapies seek to improve its risk benefit ratio through enhanced control of the focality of stimulation. The design of seizure therapies with increased spatial precision is motivated by avoiding stimulation of deep brain structures implicated in memory retention, including the hippocampus. The development of two innovations in seizure therapy-individualized low-amplitude seizure therapy (iLAST) and magnetic seizure therapy (MST), are detailed. iLAST is a method of seizure titration involving reducing current spread in the brain by titrating current amplitude from the traditional fixed amplitudes. MST, which can be used in conjunction with iLAST dosing methods, involves the use of magnetic stimulation to reduce shunting and spreading of current by the scalp occurring during electrical stimulation. Evidence is presented on the rationale for increasing the focality of ECT in hopes of preserving its effectiveness, while reducing cognitive side-effects. Finally, the value of electric field and neural modelling is illustrated to explain observed clinical effects of modifications to ECT technique, and their utility in the rational design of the next generation of seizure therapies.

The Effect of a Transcranial Channel as a Skull/Brain Interface in High-Definition Transcranial Direct Current Stimulation—A Computational Study

PubMed Central

Seo, Hyeon; Kim, Hyoung-Ihl; Jun, Sung Chan

2017-01-01

A transcranial channel is an interface between the skull and brain; it consists of a biocompatible and highly conductive material that helps convey the current induced by transcranial direct current stimulation (tDCS) to the target area. However, it has been proposed only conceptually, and there has been no concrete study of its efficacy. In this work, we conducted a computational investigation of this conceptual transcranial model with high-definition tDCS, inducing focalized neuromodulation to determine whether inclusion of a transcranial channel performs effectively. To do so, we constructed an anatomically realistic head model and compartmental pyramidal neuronal models. We analyzed membrane polarization by extracellular stimulation and found that the inclusion of a transcranial channel induced polarization at the target area 11 times greater than conventional HD-tDCS without the transcranial channel. Furthermore, the stimulation effect of the transcranial channel persisted up to approximately 80%, even when the stimulus electrodes were displaced approximately 5 mm from the target area. We investigated the efficacy of the transcranial channel and found that greatly improved stimulation intensity and focality may be achieved. Thus, the use of these channels may be promising for clinical treatment. PMID:28084429

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.

Long-term evaluation of impedance levels and clinical development in subthalamic deep brain stimulation for Parkinson's disease.

PubMed

Hartmann, C J; Wojtecki, L; Vesper, J; Volkmann, J; Groiss, S J; Schnitzler, A; Südmeyer, M

2015-10-01

This study was conducted to better understand the development of clinical efficacy and impedance levels in the long-term course of deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's disease (PD). In this retrospective study of twenty PD patients, the motor part of the Unified Parkinson's Disease Rating Scale was periodically assessed i) after withdrawal of medication and inactivated stimulation, ii) after withdrawal of medication with activated stimulation and iii) after challenge with l-Dopa during activated stimulation up to 13 years after surgery. STN-DBS with or without medication significantly improved motor function up to 13 years after surgery. The contribution of axial symptoms increased over time. While the stimulation parameters were kept constant, the therapeutic impedances progressively declined. STN-DBS in PD remains effective in the long-term course of the disease. Constant current stimulation might be preferable over voltage-controlled stimulation, as it would alleviate the impact of impedance changes on the volume of tissue activated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Systems for deep brain stimulation: review of technical features.

PubMed

Amon, A; Alesch, F

2017-09-01

The use of deep brain stimulation (DBS) is an important treatment option for movement disorders and other medical conditions. Today, three major manufacturers provide implantable systems for DBS. Although the underlying principle is basically the same for all available systems, the differences in the technical features vary considerably. This article outlines aspects regarding the technical features of DBS systems. The differences between voltage and current sources are addressed and their effect on stimulation is shown. To maintain clinical benefit and minimize side effects the stimulation field has to be adapted to the requirements of the patient. Shaping of the stimulation field can be achieved by the electrode design and polarity configuration. Furthermore, the electric signal consisting of stimulation rate, stimulation amplitude and pulse width affect the stimulation field. Interleaving stimulation is an additional concept, which permits improved treatment outcomes. Therefore, the electrode design, the polarity, the electric signal, and the concept of interleaving stimulation are presented. The investigated systems can be also categorized as rechargeable and non-rechargeable, which is briefly discussed. Options for interconnecting different system components from various manufacturers are presented. The present paper summarizes the technical features and their combination possibilities, which can have a major impact on the therapeutic effect.

Regional anatomy of the pedunculopontine nucleus: relevance for deep brain stimulation.

PubMed

Fournier-Gosselin, Marie-Pierre; Lipsman, Nir; Saint-Cyr, Jean A; Hamani, Clement; Lozano, Andres M

2013-09-01

The pedunculopontine nucleus (PPN) is currently being investigated as a potential deep brain stimulation target to improve gait and posture in Parkinson's disease. This review examines the complex anatomy of the PPN region and suggests a functional mapping of the surrounding nuclei and fiber tracts that may serve as a guide to a more accurate placement of electrodes while avoiding potentially adverse effects. The relationships of the PPN were examined in different human brain atlases. Schematic representations of those structures in the vicinity of the PPN were generated and correlated with their potential stimulation effects. By providing a functional map and representative schematics of the PPN region, we hope to optimize the placement of deep brain stimulation electrodes, thereby maximizing safety and clinical efficacy. © 2013 International Parkinson and Movement Disorder Society.

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 cerebellar hemisphere in combination with cathodal transcutaneous spinal direct current stimulation might be useful to boost the effects of robot-assisted gait training in chronic brain stroke patients with walking impairment.

Single-Session Transcranial Direct Current Stimulation Temporarily Improves Symptoms, Mood, and Self-Regulatory Control in Bulimia Nervosa: A Randomised Controlled Trial.

PubMed

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

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. This double-blind sham-controlled proof-of-principle trial investigated the effects of bilateral tDCS over the DLPFC in adults with BN. 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. 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. 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.

Dual-hemisphere transcranial direct current stimulation over primary motor cortex enhances consolidation of a ballistic thumb movement.

PubMed

Koyama, Soichiro; Tanaka, Satoshi; Tanabe, Shigeo; Sadato, Norihiro

2015-02-19

Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates motor performance and learning. Previous studies have shown that tDCS over the primary motor cortex (M1) can facilitate consolidation of various motor skills. However, the effect of tDCS on consolidation of newly learned ballistic movements remains unknown. The present study tested the hypothesis that tDCS over M1 enhances consolidation of ballistic thumb movements in healthy adults. Twenty-eight healthy subjects participated in an experiment with a single-blind, sham-controlled, between-group design. Fourteen subjects practiced a ballistic movement with their left thumb during dual-hemisphere tDCS. Subjects received 1mA anodal tDCS over the contralateral M1 and 1mA cathodal tDCS over the ipsilateral M1 for 25min during the training session. The remaining 14 subjects underwent identical training sessions, except that dual-hemisphere tDCS was applied for only the first 15s (sham group). All subjects performed the task again at 1h and 24h later. Primary measurements examined improvement in peak acceleration of the ballistic thumb movement at 1h and 24h after stimulation. Improved peak acceleration was significantly greater in the tDCS group (144.2±15.1%) than in the sham group (98.7±9.1%) (P<0.05) at 24h, but not 1h, after stimulation. Thus, dual-hemisphere tDCS over M1 enhanced consolidation of ballistic thumb movement in healthy adults. Dual-hemisphere tDCS over M1 may be useful to improve elemental motor behaviors, such as ballistic movements, in patients with subcortical strokes. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

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

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.

Working memory capacity differentially influences responses to tDCS and HD-tDCS in a retro-cue task.

PubMed

Gözenman, Filiz; Berryhill, Marian E

2016-08-26

There is growing interest in non-invasive brain stimulation techniques. A drawback is that the relationship between stimulation and cognitive outcomes for various tasks are unknown. Transcranial direct current stimulation (tDCS) provides diffuse current spread, whereas high-definition tDCS (HD-tDCS) provides more targeted current. The direction of behavioral effects after tDCS can be difficult to predict in cognitive realms such as attention and working memory (WM). Previously, we showed that in low and high WM capacity groups tDCS modulates performance in nearly equal and opposite directions on a change detection task, with improvement for the high capacity participants alone. Here, we used the retro-cue paradigm to test attentional shifting among items in WM to investigate whether WM capacity (WMC) predicted different behavioral consequences during anodal tDCS or HD-tDCS to posterior parietal cortex (PPC). In two experiments, with 24 participants each, we used different stimulus categories (colored circles, letters) and stimulation sites (right, left PPC). The results showed a significant (Experiment 1) or trending (Experiment 2) WMC x stimulation interaction. Compared to tDCS, after HD-tDCS the retro-cueing benefit was significantly greater for the low WMC group but numerically worse for the high WMC group. These data highlight the importance of considering group differences when using non-invasive neurostimulation techniques. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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.

Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation

NASA Technical Reports Server (NTRS)

Andrews, Russell J.

2003-01-01

Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

Neuroprotection trek--the next generation: neuromodulation I. Techniques--deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation.

PubMed

Andrews, Russell J

2003-05-01

Neuromodulation denotes controlled electrical stimulation of the central or peripheral nervous system. The three forms of neuromodulation described in this paper-deep brain stimulation, vagus nerve stimulation, and transcranial magnetic stimulation-were chosen primarily for their demonstrated or potential clinical usefulness. Deep brain stimulation is a completely implanted technique for improving movement disorders, such as Parkinson's disease, by very focal electrical stimulation of the brain-a technique that employs well-established hardware (electrode and pulse generator/battery). Vagus nerve stimulation is similar to deep brain stimulation in being well-established (for the treatment of refractory epilepsy), completely implanted, and having hardware that can be considered standard at the present time. Vagus nerve stimulation differs from deep brain stimulation, however, in that afferent stimulation of the vagus nerve results in diffuse effects on many regions throughout the brain. Although use of deep brain stimulation for applications beyond movement disorders will no doubt involve placing the stimulating electrode(s) in regions other than the thalamus, subthalamus, or globus pallidus, the use of vagus nerve stimulation for applications beyond epilepsy-for example, depression and eating disorders-is unlikely to require altering the hardware significantly (although stimulation protocols may differ). Transcranial magnetic stimulation is an example of an external or non-implanted, intermittent (at least given the current state of the hardware) stimulation technique, the clinical value of which for neuromodulation and neuroprotection remains to be determined.

A Power-Efficient Wireless System With Adaptive Supply Control for Deep Brain Stimulation.

PubMed

Lee, Hyung-Min; Park, Hangue; Ghovanloo, Maysam

2013-09-01

A power-efficient wireless stimulating system for a head-mounted deep brain stimulator (DBS) is presented. A new adaptive rectifier generates a variable DC supply voltage from a constant AC power carrier utilizing phase control feedback, while achieving high AC-DC power conversion efficiency (PCE) through active synchronous switching. A current-controlled stimulator adopts closed-loop supply control to automatically adjust the stimulation compliance voltage by detecting stimulation site potentials through a voltage readout channel, and improve the stimulation efficiency. The stimulator also utilizes closed-loop active charge balancing to maintain the residual charge at each site within a safe limit, while receiving the stimulation parameters wirelessly from the amplitude-shift-keyed power carrier. A 4-ch wireless stimulating system prototype was fabricated in a 0.5-μm 3M2P standard CMOS process, occupying 2.25 mm². With 5 V peak AC input at 2 MHz, the adaptive rectifier provides an adjustable DC output between 2.5 V and 4.6 V at 2.8 mA loading, resulting in measured PCE of 72 ~ 87%. The adaptive supply control increases the stimulation efficiency up to 30% higher than a fixed supply voltage to 58 ~ 68%. The prototype wireless stimulating system was verified in vitro .

A Power-Efficient Wireless System With Adaptive Supply Control for Deep Brain Stimulation

PubMed Central

Lee, Hyung-Min; Park, Hangue; Ghovanloo, Maysam

2014-01-01

A power-efficient wireless stimulating system for a head-mounted deep brain stimulator (DBS) is presented. A new adaptive rectifier generates a variable DC supply voltage from a constant AC power carrier utilizing phase control feedback, while achieving high AC-DC power conversion efficiency (PCE) through active synchronous switching. A current-controlled stimulator adopts closed-loop supply control to automatically adjust the stimulation compliance voltage by detecting stimulation site potentials through a voltage readout channel, and improve the stimulation efficiency. The stimulator also utilizes closed-loop active charge balancing to maintain the residual charge at each site within a safe limit, while receiving the stimulation parameters wirelessly from the amplitude-shift-keyed power carrier. A 4-ch wireless stimulating system prototype was fabricated in a 0.5-μm 3M2P standard CMOS process, occupying 2.25 mm². With 5 V peak AC input at 2 MHz, the adaptive rectifier provides an adjustable DC output between 2.5 V and 4.6 V at 2.8 mA loading, resulting in measured PCE of 72 ~ 87%. The adaptive supply control increases the stimulation efficiency up to 30% higher than a fixed supply voltage to 58 ~ 68%. The prototype wireless stimulating system was verified in vitro. PMID:24678126

High frequency switched-mode stimulation can evoke post synaptic responses in cerebellar principal neurons

PubMed Central

van Dongen, Marijn N.; Hoebeek, Freek E.; Koekkoek, S. K. E.; De Zeeuw, Chris I.; Serdijn, Wouter A.

2015-01-01

This paper investigates the efficacy of high frequency switched-mode neural stimulation. Instead of using a constant stimulation amplitude, the stimulus is switched on and off repeatedly with a high frequency (up to 100 kHz) duty cycled signal. By means of tissue modeling that includes the dynamic properties of both the tissue material as well as the axon membrane, it is first shown that switched-mode stimulation depolarizes the cell membrane in a similar way as classical constant amplitude stimulation. These findings are subsequently verified using in vitro experiments in which the response of a Purkinje cell is measured due to a stimulation signal in the molecular layer of the cerebellum of a mouse. For this purpose a stimulator circuit is developed that is able to produce a monophasic high frequency switched-mode stimulation signal. The results confirm the modeling by showing that switched-mode stimulation is able to induce similar responses in the Purkinje cell as classical stimulation using a constant current source. This conclusion opens up possibilities for novel stimulation designs that can improve the performance of the stimulator circuitry. Care has to be taken to avoid losses in the system due to the higher operating frequency. PMID:25798105

The Effect of Cerebellar Transcranial Direct Current Stimulation on A Throwing Task Depends on Individual Level of Task Performance.

PubMed

Mizuguchi, Nobuaki; Katayama, Takashi; Kanosue, Kazuyuki

2018-02-10

The effect of cerebellar transcranial direct current stimulation (tDCS) on motor performance remains controversial. Some studies suggest that the effect of tDCS depends upon task-difficulty and individual level of task performance. Here, we investigated whether the effect of cerebellar tDCS on the motor performance depends upon the individual's level of performance. Twenty-four naïve participants practiced dart throwing while receiving a 2-mA cerebellar tDCS for 20 min under three stimulus conditions (anodal-, cathodal-, and sham-tDCS) on separate days with a double-blind, counter-balanced cross-over design. Task performance was assessed by measuring the distance between the center of the bull's eye and the dart's position. Although task performance tended to improve throughout the practice under all stimulus conditions, improvement within a given day was not significant as compared to the first no-stimulus block. In addition, improvement did not differ among stimulation conditions. However, the magnitude of improvement was associated with an individual's level of task performance only under cathodal tDCS condition (p < 0.05). This resulted in a significant performance improvement only for the sub-group of participants with lower performance levels as compared to that with sham-tDCS (p < 0.05). These findings suggest that the facilitation effect of cerebellar cathodal tDCS on motor skill learning of complex whole-body movements depends on the level of an individual's task performance. Thus, cerebellar tDCS would facilitate learning of a complex motor skill task only in a subset of individuals. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

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.

Electrical stimulation of gut motility guided by an in silico model

NASA Astrophysics Data System (ADS)

Barth, Bradley B.; Henriquez, Craig S.; Grill, Warren M.; Shen, Xiling

2017-12-01

Objective. Neuromodulation of the central and peripheral nervous systems is becoming increasingly important for treating a diverse set of diseases—ranging from Parkinson’s Disease and epilepsy to chronic pain. However, neuromodulation of the gastrointestinal (GI) tract has achieved relatively limited success in treating functional GI disorders, which affect a significant population, because the effects of stimulation on the enteric nervous system (ENS) and gut motility are not well understood. Here we develop an integrated neuromechanical model of the ENS and assess neurostimulation strategies for enhancing gut motility, validated by in vivo experiments. Approach. The computational model included a network of enteric neurons, smooth muscle fibers, and interstitial cells of Cajal, which regulated propulsion of a virtual pellet in a model of gut motility. Main results. Simulated extracellular stimulation of ENS-mediated motility revealed that sinusoidal current at 0.5 Hz was more effective at increasing intrinsic peristalsis and reducing colon transit time than conventional higher frequency rectangular current pulses, as commonly used for neuromodulation therapy. Further analysis of the model revealed that the 0.5 Hz sinusoidal currents were more effective at modulating the pacemaker frequency of interstitial cells of Cajal. To test the predictions of the model, we conducted in vivo electrical stimulation of the distal colon while measuring bead propulsion in awake rats. Experimental results confirmed that 0.5 Hz sinusoidal currents were more effective than higher frequency pulses at enhancing gut motility. Significance. This work demonstrates an in silico GI neuromuscular model to enable GI neuromodulation parameter optimization and suggests that low frequency sinusoidal currents may improve the efficacy of GI pacing.

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.

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

Clinical Pilot Study and Computational Modeling of Bitemporal Transcranial Direct Current Stimulation, and Safety of Repeated Courses of Treatment, in Major Depression.

PubMed

Ho, Kerrie-Anne; Bai, Siwei; Martin, Donel; Alonzo, Angelo; Dokos, Socrates; Loo, Colleen K

2015-12-01

This study aimed to examine a bitemporal (BT) transcranial direct current stimulation (tDCS) electrode montage for the treatment of depression through a clinical pilot study and computational modeling. The safety of repeated courses of stimulation was also examined. Four participants with depression who had previously received multiple courses of tDCS received a 4-week course of BT tDCS. Mood and neuropsychological function were assessed. The results were compared with previous courses of tDCS given to the same participants using different electrode montages. Computational modeling examined the electric field maps produced by the different montages. Three participants showed clinical improvement with BT tDCS (mean [SD] improvement, 49.6% [33.7%]). There were no adverse neuropsychological effects. Computational modeling showed that the BT montage activates the anterior cingulate cortices and brainstem, which are deep brain regions that are important for depression. However, a fronto-extracephalic montage stimulated these areas more effectively. No adverse effects were found in participants receiving up to 6 courses of tDCS. Bitemporal tDCS was safe and led to clinically meaningful efficacy in 3 of 4 participants. However, computational modeling suggests that the BT montage may not activate key brain regions in depression more effectively than another novel montage--fronto-extracephalic tDCS. There is also preliminary evidence to support the safety of up to 6 repeated courses of tDCS.

Minimum Electric Field Exposure for Seizure Induction with Electroconvulsive Therapy and Magnetic Seizure Therapy.

PubMed

Lee, Won H; Lisanby, Sarah H; Laine, Andrew F; Peterchev, Angel V

2017-05-01

Lowering and individualizing the current amplitude in electroconvulsive therapy (ECT) has been proposed as a means to produce stimulation closer to the neural activation threshold and more focal seizure induction, which could potentially reduce cognitive side effects. However, the effect of current amplitude on the electric field (E-field) in the brain has not been previously linked to the current amplitude threshold for seizure induction. We coupled MRI-based E-field models with amplitude titrations of motor threshold (MT) and seizure threshold (ST) in four nonhuman primates (NHPs) to determine the strength, distribution, and focality of stimulation in the brain for four ECT electrode configurations (bilateral, bifrontal, right-unilateral, and frontomedial) and magnetic seizure therapy (MST) with cap coil on vertex. At the amplitude-titrated ST, the stimulated brain subvolume (23-63%) was significantly less than for conventional ECT with high, fixed current (94-99%). The focality of amplitude-titrated right-unilateral ECT (25%) was comparable to cap coil MST (23%), demonstrating that ECT with a low current amplitude and focal electrode placement can induce seizures with E-field as focal as MST, although these electrode and coil configurations affect differently specific brain regions. Individualizing the current amplitude reduced interindividual variation in the stimulation focality by 40-53% for ECT and 26% for MST, supporting amplitude individualization as a means of dosing especially for ECT. There was an overall significant correlation between the measured amplitude-titrated ST and the prediction of the E-field models, supporting a potential role of these models in dosing of ECT and MST. These findings may guide the development of seizure therapy dosing paradigms with improved risk/benefit ratio.

Responses evoked by a vestibular implant providing chronic stimulation.

PubMed

Thompson, Lara A; Haburcakova, Csilla; Gong, Wangsong; Lee, Daniel J; Wall, Conrad; Merfeld, Daniel M; Lewis, Richard F

2012-01-01

Patients with bilateral vestibular loss experience dehabilitating visual, perceptual, and postural difficulties, and an implantable vestibular prosthesis that could improve these symptoms would be of great benefit to these patients. In previous work, we have shown that a one-dimensional, unilateral canal prosthesis can improve the vestibulooccular reflex (VOR) in canal-plugged squirrel monkeys. In addition to the VOR, the potential effects of a vestibular prosthesis on more complex, highly integrative behaviors, such as the perception of head orientation and posture have remained unclear. We tested a one-dimensional, unilateral prosthesis in a rhesus monkey with bilateral vestibular loss and found that chronic electrical stimulation partially restored the compensatory VOR and also that percepts of head orientation relative to gravity were improved. However, the one-dimensional prosthetic stimulation had no clear effect on postural stability during quiet stance, but sway evoked by head-turns was modestly reduced. These results suggest that not only can the implementation of a vestibular prosthesis provide partial restitution of VOR but may also improve perception and posture in the presence of bilateral vestibular hypofunction (BVH). In this review, we provide an overview of our previous and current work directed towards the eventual clinical implementation of an implantable vestibular prosthesis.

Using Institutional Effectiveness Data To Stimulate Improvement...Getting Data off the Shelf and into the Hands of Stakeholders. AIR 2000 Annual Forum Paper.

ERIC Educational Resources Information Center

Hill, Sandy; Willekens, Rene G.

This paper outlines a successful, stakeholder driven, continuous improvement process that is currently used at Estrella Mountain Community College, Arizona. The process is designed to address the next step of what to do with institutional effectiveness data after it has been collected and reported. Many institutional effectiveness processes stop…

[Analysis of the Cochrane Review: Interventions for Improving Upper Limb Function after Stroke. Cochrane Database Syst Rev. 2014,11:CD010820].

PubMed

Sousa Nanji, Liliana; Torres Cardoso, André; Costa, João; Vaz-Carneiro, António

2015-01-01

Impairment of the upper limbs is quite frequent after stroke, making rehabilitation an essential step towards clinical recovery and patient empowerment. This review aimed to synthetize existing evidence regarding interventions for upper limb function improvement after Stroke and to assess which would bring some benefit. The Cochrane Database of Systematic Reviews, the Database of Reviews of Effects and PROSPERO databases were searched until June 2013 and 40 reviews have been included, covering 503 studies, 18 078 participants and 18 interventions, as well as different doses and settings of interventions. The main results were: 1- Information currently available is insufficient to assess effectiveness of each intervention and to enable comparison of interventions; 2- Transcranial direct current stimulation brings no benefit for outcomes of activities of daily living; 3- Moderate-quality evidence showed a beneficial effect of constraint-induced movement therapy, mental practice, mirror therapy, interventions for sensory impairment, virtual reality and repetitive task practice; 4- Unilateral arm training may be more effective than bilateral arm training; 5- Moderate-quality evidence showed a beneficial effect of robotics on measures of impairment and ADLs; 6- There is no evidence of benefit or harm for technics such as repetitive transcranial magnetic stimulation, music therapy, pharmacological interventions, electrical stimulation and other therapies. Currently available evidence is insufficient and of low quality, not supporting clear clinical decisions. High-quality studies are still needed.

Targeting the Cerebellum by Noninvasive Neurostimulation: a Review.

PubMed

van Dun, Kim; Bodranghien, Florian; Manto, Mario; Mariën, Peter

2017-06-01

Transcranial magnetic and electric stimulation of the brain are novel and highly promising techniques currently employed in both research and clinical practice. Improving or rehabilitating brain functions by modulating excitability with these noninvasive tools is an exciting new area in neuroscience. Since the cerebellum is closely connected with the cerebral regions subserving motor, associative, and affective functions, the cerebello-thalamo-cortical pathways are an interesting target for these new techniques. Targeting the cerebellum represents a novel way to modulate the excitability of remote cortical regions and their functions. This review brings together the studies that have applied cerebellar stimulation, magnetic and electric, and presents an overview of the current knowledge and unsolved issues. Some recommendations for future research are implemented as well.

Neural substrates underlying stimulation-enhanced motor skill learning after stroke.

PubMed

Lefebvre, Stéphanie; Dricot, Laurence; Laloux, Patrice; Gradkowski, Wojciech; Desfontaines, Philippe; Evrard, Frédéric; Peeters, André; Jamart, Jacques; Vandermeeren, Yves

2015-01-01

Motor skill learning is one of the key components of motor function recovery after stroke, especially recovery driven by neurorehabilitation. Transcranial direct current stimulation can enhance neurorehabilitation and motor skill learning in stroke patients. However, the neural mechanisms underlying the retention of stimulation-enhanced motor skill learning involving a paretic upper limb have not been resolved. These neural substrates were explored by means of functional magnetic resonance imaging. Nineteen chronic hemiparetic stroke patients participated in a double-blind, cross-over randomized, sham-controlled experiment with two series. Each series consisted of two sessions: (i) an intervention session during which dual transcranial direct current stimulation or sham was applied during motor skill learning with the paretic upper limb; and (ii) an imaging session 1 week later, during which the patients performed the learned motor skill. The motor skill learning task, called the 'circuit game', involves a speed/accuracy trade-off and consists of moving a pointer controlled by a computer mouse along a complex circuit as quickly and accurately as possible. Relative to the sham series, dual transcranial direct current stimulation applied bilaterally over the primary motor cortex during motor skill learning with the paretic upper limb resulted in (i) enhanced online motor skill learning; (ii) enhanced 1-week retention; and (iii) superior transfer of performance improvement to an untrained task. The 1-week retention's enhancement driven by the intervention was associated with a trend towards normalization of the brain activation pattern during performance of the learned motor skill relative to the sham series. A similar trend towards normalization relative to sham was observed during performance of a simple, untrained task without a speed/accuracy constraint, despite a lack of behavioural difference between the dual transcranial direct current stimulation and sham series. Finally, dual transcranial direct current stimulation applied during the first session enhanced continued learning with the paretic limb 1 week later, relative to the sham series. This lasting behavioural enhancement was associated with more efficient recruitment of the motor skill learning network, that is, focused activation on the motor-premotor areas in the damaged hemisphere, especially on the dorsal premotor cortex. Dual transcranial direct current stimulation applied during motor skill learning with a paretic upper limb resulted in prolonged shaping of brain activation, which supported behavioural enhancements in stroke patients. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Inositol Treatment and ART Outcomes in Women with PCOS.

PubMed

Garg, Deepika; Tal, Reshef

2016-01-01

Polycystic ovary syndrome (PCOS) affects 5-10% of women in reproductive age and is characterized by oligo/amenorrhea, androgen excess, insulin resistance, and typical polycystic ovarian morphology. It is the most common cause of infertility secondary to ovulatory dysfunction. The underlying etiology is still unknown but is believed to be multifactorial. Insulin-sensitizing compounds such as inositol, a B-complex vitamin, and its stereoisomers (myo-inositol and D-chiro-inositol) have been studied as an effective treatment of PCOS. Administration of inositol in PCOS has been shown to improve not only the metabolic and hormonal parameters but also ovarian function and the response to assisted-reproductive technology (ART). Accumulating evidence suggests that it is also capable of improving folliculogenesis and embryo quality and increasing the mature oocyte yield following ovarian stimulation for ART in women with PCOS. In the current review, we collate the evidence and summarize our current knowledge on ovarian stimulation and ART outcomes following inositol treatment in women with PCOS undergoing in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI).

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.

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

Methadone but not morphine inhibits lubiprostone-stimulated Cl- currents in T84 intestinal cells and recombinant human ClC-2, but not CFTR Cl- currents.

PubMed

Cuppoletti, John; Chakrabarti, Jayati; Tewari, Kirti; Malinowska, Danuta H

2013-05-01

In clinical trials, methadone, but not morphine, appeared to prevent beneficial effects of lubiprostone, a ClC-2 Cl(-) channel activator, on opioid-induced constipation. Effects of methadone and morphine on lubiprostone-stimulated Cl(-) currents were measured by short circuit current (Isc) across T84 cells. Whole cell patch clamp of human ClC-2 (hClC-2) stably expressed in HEK293 cells and in a high expression cell line (HEK293EBNA) as well as human CFTR (hCFTR) stably expressed in HEK293 cells was used to study methadone and morphine effects on recombinant hClC-2 and hCFTR Cl(-) currents. Methadone but not morphine inhibited lubiprostone-stimulated Isc in T84 cells with half-maximal inhibition at 100 nM. Naloxone did not affect lubiprostone stimulation or methadone inhibition of Isc. Lubiprostone-stimulated Cl(-) currents in hClC-2/HEK293 cells, but not forskolin/IBMX-stimulated Cl(-) currents in hCFTR/HEK293 cells, were inhibited by methadone, but not morphine. HEK293EBNA cells expressing hClC-2 showed time-dependent, voltage-activated, CdCl2-inhibited Cl(-) currents in the absence (control) and the presence of lubiprostone. Methadone, but not morphine, inhibited control and lubiprostone-stimulated hClC-2 Cl(-) currents with half-maximal inhibition at 100 and 200-230 nM, respectively. Forskolin/IBMX-stimulated hClC-2 Cl(-) currents were also inhibited by methadone. Myristoylated protein kinase inhibitor (a specific PKA inhibitor) inhibited forskolin/IBMX- but not lubiprostone-stimulated hClC-2 Cl(-) currents. Methadone caused greater inhibition of lubiprostone-stimulated currents added before patching (66.1 %) compared with after patching (28.7 %). Methadone caused inhibition of lubiprostone-stimulated Cl(-) currents in T84 cells and control; lubiprostone- and forskolin/IBMX-stimulated recombinant hClC-2 Cl(-) currents may be the basis for reduced efficacy of lubiprostone in methadone-treated patients.

Electrical stimulation vs. pulsed and continuous-wave optical stimulation of the rat prostate cavernous nerves, in vivo

NASA Astrophysics Data System (ADS)

Perkins, William C.; Lagoda, Gwen A.; Burnett, Arthur; Fried, Nathaniel M.

2015-07-01

Identification and preservation of the cavernous nerves (CNs) during prostate cancer surgery is critical for post-operative sexual function. Electrical nerve stimulation (ENS) mapping has previously been tested as an intraoperative tool for CN identification, but was found to be unreliable. ENS is limited by the need for electrode-tissue contact, poor spatial precision from electrical current spreading, and stimulation artifacts interfering with detection. Alternatively, optical nerve stimulation (ONS) provides noncontact stimulation, improved spatial selectivity, and elimination of stimulation artifacts. This study compares ENS to pulsed/CW ONS to explore the ONS mechanism. A total of eighty stimulations were performed in 5 rats, in vivo. ENS (4 V, 5 ms, 10 Hz) was compared to ONS using a pulsed diode laser nerve stimulator (1873 nm, 5 ms, 10 Hz) or CW diode laser nerve stimulator (1455 nm). Intracavernous pressure (ICP) response and nerve compound action potentials (nCAPs) were measured. All three stimulation modes (ENS, ONS-CW, ONS-P) produced comparable ICP magnitudes. However, ENS demonstrated more rapid ICP response times and well defined nCAPs compared to unmeasurable nCAPs for ONS. Further experiments measuring single action potentials during ENS and ONS are warranted to further understand differences in the ENS and ONS mechanisms.

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.

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

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

PubMed

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

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. 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. 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. 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. ClinicalTrials.gov NCT01968512.

Evidence Gaps in the Use of Spinal Cord Stimulation for Treating Chronic Spine Conditions.

PubMed

Provenzano, David A; Amirdelfan, Kasra; Kapural, Leonardo; Sitzman, B Todd

2017-07-15

A review of literature. The aim of this study was to define and explore the current evidence gaps in the use of spinal cord stimulation (SCS) for treating chronic spine conditions. Although over the last 40 years SCS therapy has undergone significant technological advancements, evidence gaps still exist. A literature review was conducted to define current evidence gaps for the use of SCS. Areas of focus included 1) treatment of cervical spine conditions, 2) treatment of lumbar spine conditions, 3) technological advancement and device selection, 4) appropriate patient selection, 5) the ability to curb pharmacological treatment, and 6) methods to prolong efficacy over time. New SCS strategies using advanced waveforms are explored. The efficacy, safety, and cost-effectiveness of traditional SCS for chronic pain conditions are well-established. Evidence gaps do exist. Recently, advancement in waveforms and programming parameters have allowed for paresthesia-reduced/free stimulation that in specific clinical areas may improve clinical outcomes. New waveforms such as 10-kHz high-frequency have resulted in an improvement in back coverage. To date, clinical efficacy data are more prevalent for the treatment of painful conditions originating from the lumbar spine in comparison to the cervical spine. Evidence gaps still exist that require appropriate study designs with long-term follow-up to better define and improve the use of this therapy for the treatment of chronic spine pain in both the cervical and lumbar regions. N/A.

Boosting Cognition: Effects of Multiple-Session Transcranial Direct Current Stimulation on Working Memory.

PubMed

Talsma, Lotte J; Kroese, Henryk A; Slagter, Heleen A

2017-04-01

Transcranial direct current stimulation (tDCS) is a promising tool for neurocognitive enhancement. Several studies have shown that just a single session of tDCS over the left dorsolateral pFC (lDLPFC) can improve the core cognitive function of working memory (WM) in healthy adults. Yet, recent studies combining multiple sessions of anodal tDCS over lDLPFC with verbal WM training did not observe additional benefits of tDCS in subsequent stimulation sessions nor transfer of benefits to novel WM tasks posttraining. Using an enhanced stimulation protocol as well as a design that included a baseline measure each day, the current study aimed to further investigate the effects of multiple sessions of tDCS on WM. Specifically, we investigated the effects of three subsequent days of stimulation with anodal (20 min, 1 mA) versus sham tDCS (1 min, 1 mA) over lDLPFC (with a right supraorbital reference) paired with a challenging verbal WM task. WM performance was measured with a verbal WM updating task (the letter n-back) in the stimulation sessions and several WM transfer tasks (different letter set n-back, spatial n-back, operation span) before and 2 days after stimulation. Anodal tDCS over lDLPFC enhanced WM performance in the first stimulation session, an effect that remained visible 24 hr later. However, no further gains of anodal tDCS were observed in the second and third stimulation sessions, nor did benefits transfer to other WM tasks at the group level. Yet, interestingly, post hoc individual difference analyses revealed that in the anodal stimulation group the extent of change in WM performance on the first day of stimulation predicted pre to post changes on both the verbal and the spatial transfer task. Notably, this relationship was not observed in the sham group. Performance of two individuals worsened during anodal stimulation and on the transfer tasks. Together, these findings suggest that repeated anodal tDCS over lDLPFC combined with a challenging WM task may be an effective method to enhance domain-independent WM functioning in some individuals, but not others, or can even impair WM. They thus call for a thorough investigation into individual differences in tDCS respondence as well as further research into the design of multisession tDCS protocols that may be optimal for boosting cognition across a wide range of individuals.

Higher success rate with transcranial electrical stimulation of motor-evoked potentials using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery.

PubMed

Shigematsu, Hideki; Kawaguchi, Masahiko; Hayashi, Hironobu; Takatani, Tsunenori; Iwata, Eiichiro; Tanaka, Masato; Okuda, Akinori; Morimoto, Yasuhiko; Masuda, Keisuke; Tanaka, Yuu; Tanaka, Yasuhito

2017-10-01

During spine surgery, the spinal cord is electrophysiologically monitored via transcranial electrical stimulation of motor-evoked potentials (TES-MEPs) to prevent injury. Transcranial electrical stimulation of motor-evoked potential involves the use of either constant-current or constant-voltage stimulation; however, there are few comparative data available regarding their ability to adequately elicit compound motor action potentials. We hypothesized that the success rates of TES-MEP recordings would be similar between constant-current and constant-voltage stimulations in patients undergoing spine surgery. The objective of this study was to compare the success rates of TES-MEP recordings between constant-current and constant-voltage stimulation. This is a prospective, within-subject study. Data from 100 patients undergoing spinal surgery at the cervical, thoracic, or lumbar level were analyzed. The success rates of the TES-MEP recordings from each muscle were examined. Transcranial electrical stimulation with constant-current and constant-voltage stimulations at the C3 and C4 electrode positions (international "10-20" system) was applied to each patient. Compound muscle action potentials were bilaterally recorded from the abductor pollicis brevis (APB), deltoid (Del), abductor hallucis (AH), tibialis anterior (TA), gastrocnemius (GC), and quadriceps (Quad) muscles. The success rates of the TES-MEP recordings from the right Del, right APB, bilateral Quad, right TA, right GC, and bilateral AH muscles were significantly higher using constant-voltage stimulation than those using constant-current stimulation. The overall success rates with constant-voltage and constant-current stimulations were 86.3% and 68.8%, respectively (risk ratio 1.25 [95% confidence interval: 1.20-1.31]). The success rates of TES-MEP recordings were higher using constant-voltage stimulation compared with constant-current stimulation in patients undergoing spinal surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

Pathways of translation: deep brain stimulation.

PubMed

Gionfriddo, Michael R; Greenberg, Alexandra J; Wahegaonkar, Abhijeet L; Lee, Kendall H

2013-12-01

Electrical stimulation of the brain has a 2000 year history. Deep brain stimulation (DBS), one form of neurostimulation, is a functional neurosurgical approach in which a high-frequency electrical current stimulates targeted brain structures for therapeutic benefit. It is an effective treatment for certain neuropathologic movement disorders and an emerging therapy for psychiatric conditions and epilepsy. Its translational journey did not follow the typical bench-to-bedside path, but rather reversed the process. The shift from ancient and medieval folkloric remedy to accepted medical practice began with independent discoveries about electricity during the 19th century and was fostered by technological advances of the 20th. In this paper, we review that journey and discuss how the quest to expand its applications and improve outcomes is taking DBS from the bedside back to the bench. © 2013 Wiley Periodicals, Inc.

Phrenic Nerve Stimulation: Technology and Clinical Applications.

PubMed

Abdunnur, Shane V; Kim, Daniel H

2015-01-01

Phrenic nerve stimulation is a technique used to reanimate the diaphragm of patients with central nervous system etiologies of respiratory insufficiency. Current clinical indications include congenital central hypoventilation syndrome, spinal cord injury above C4, brain stem injury, and idiopathic severe sleep apnea. Presurgical evaluation ensures proper patient selection by validating the intact circuit from the phrenic nerve through alveolar oxygenation. The procedure involves placing leads around the phrenic nerves bilaterally and attaching these leads to radio receivers in a subcutaneous pocket. The rate and amplitude of the current is adjusted via an external radio transmitter. After implantation, each patient progresses through a conditioning phase that strengthens the diaphragm and progressively provides independence from the mechanical ventilator. Studies indicate that patients and families experience an improved quality of life and are satisfied with the results. Phrenic nerve stimulation provides a safe and effective means for reanimating the diaphragm for certain patients with respiratory insufficiency, providing independence from mechanical ventilation. © 2016 S. Karger AG, Basel.

Towards an ankle neuroprosthesis for hybrid robotics: Concepts and current sources for functional electrical stimulation.

PubMed

Casco, S; Fuster, I; Galeano, R; Moreno, J C; Pons, J L; Brunetti, F

2017-07-01

Hybrid rehabilitation robotics combine neuro-prosthetic devices (close-loop functional electrical stimulation systems) and traditional robotic structures and actuators to explore better therapies and promote a more efficient motor function recovery or compensation. Although hybrid robotics and ankle neuroprostheses (NPs) have been widely developed over the last years, there are just few studies on the use of NPs to electrically control both ankle flexion and extension to promote ankle recovery and improved gait patterns in paretic limbs. The aim of this work is to develop an ankle NP specifically designed to work in the field of hybrid robotics. This article presents early steps towards this goal and makes a brief review about motor NPs and Functional Electrical Stimulation (FES) principles and most common devices used to aid the ankle functioning during the gait cycle. It also shows a current sources analysis done in this framework, in order to choose the best one for this intended application.

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.

tDCS over the motor cortex improves lexical retrieval of action words in poststroke aphasia.

PubMed

Branscheidt, Meret; Hoppe, Julia; Zwitserlood, Pienie; Liuzzi, Gianpiero

2018-02-01

One-third of stroke survivors worldwide suffer from aphasia. Speech and language therapy (SLT) is considered effective in treating aphasia, but because of time constraints, improvements are often limited. Noninvasive brain stimulation is a promising adjuvant strategy to facilitate SLT. However, stroke might render "classical" language regions ineffective as stimulation sites. Recent work showed the effectiveness of motor cortex stimulation together with intensive naming therapy to improve outcomes in aphasia (Meinzer et al. 2016). Although that study highlights the involvement of the motor cortex, the functional aspects by which it influences language remain unclear. In the present study, we focus on the role of motor cortex in language, investigating its functional involvement in access to specific lexico-semantic (object vs. action relatedness) information in poststroke aphasia. To this end, we tested effects of anodal transcranial direct current stimulation (tDCS) to the left motor cortex on lexical retrieval in 16 patients with poststroke aphasia in a sham-controlled, double-blind study design. Critical stimuli were action and object words, and pseudowords. Participants performed a lexical decision task, deciding whether stimuli were words or pseudowords. Anodal tDCS improved accuracy in lexical decision, especially for words with action-related content and for pseudowords with an "action-like" ending ( t 15  = 2.65, P = 0.036), but not for words with object-related content and pseudowords with "object-like" characteristics. We show as a proof-of-principle that the motor cortex may play a specific role in access to lexico-semantic content. Thus motor-cortex stimulation may strengthen content-specific word-to-semantic concept associations during language treatment in poststroke aphasia. NEW & NOTEWORTHY The role of motor cortex (MC) in language processing has been debated in both health and disease. Recent work has suggested that MC stimulation together with speech and language therapy enhances outcomes in aphasia. We show that MC stimulation has a differential effect on object- and action-word processing in poststroke aphasia. We propose that MC stimulation may specifically strengthen word-to-semantic concept association in aphasia. Our results potentially provide a way to tailor therapies for language rehabilitation.

Leadership for School Improvement.

ERIC Educational Resources Information Center

Mayeski, Fran; Gaddy, Barbara B.; Goodwin, Bryan

This monograph serves two purposes: (1) to stimulate further reflection and discussion among education leaders and policymakers to revitalize and strengthen the role that school leaders play in school reform; and (2) to assist researchers in identifying areas of future work. It synthesizes some of the most current literature pertinent to…

Stimulation of the nervous system for the management of seizures: current and future developments.

PubMed

Murphy, Jerome V; Patil, Arunangelo

2003-01-01

Vagal nerve stimulation (VNS) for the treatment of refractory epilepsy appears to have started from the theory that since VNS can alter the EEG, it may influence epilepsy. It proved effective in several models of epilepsy and was then tried in short-term, open-label and double-blind trials, leading to approval in Canada, Europe and the US. Follow-up observations in these patients demonstrated continued improvement in seizure control for up to 2 years. Close to 50% of treated patients have achieved at least a 50% reduction in seizure frequency. This therapy was also useful as rescue therapy for ongoing seizures in some patients; many patients are more alert. The initial trials were completed in patients >/=12 years of age with refractory partial seizures. Subsequently, similar benefits were shown in patients with tuberous sclerosis complex, Lennox-Gastaut syndrome, hypothalamic hamartomas and primary generalised seizures. Implanting the generator and leads is technically easy, and complications are few. The method of action is largely unknown, although VNS appears to alter metabolic activity in specific brain nuclei. Considering that improvement in mood is frequently found in patients using VNS, it has undergone trials in patients with depression. Other illnesses deserving exploration with this unusual therapy are Alzheimer's disease and autism. Some aspects of VNS have proven disappointing. Although patients have fewer seizures, the number of antiepileptic drugs they take is not significantly reduced. In addition, there is no way to accurately predict the end of life of the generator. Optimal stimulation parameters, if they exist, are unknown. Deep brain stimulation is a new method for controlling medically refractory seizures. It is based on the observation that thalamic stimulation can influence the EEG over a wide area. Several thalamic nuclei have been the object of stimulation in different groups of patients. Intraoperative brain imaging is essential for electrode placement. The procedure is done under local anaesthesia. Experience with this therapy is currently limited, but growing.

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

Task-dependent and distinct roles of the temporoparietal junction and inferior frontal cortex in the control of imitation

PubMed Central

Obhi, Sukhvinder S.; Banissy, Michael J.; Santiesteban, Idalmis; Press, Clare; Catmur, Caroline; Bird, Geoffrey

2015-01-01

The control of neurological networks supporting social cognition is crucially important for social interaction. In particular, the control of imitation is directly linked to interaction quality, with impairments associated with disorders characterized by social difficulties. Previous work suggests inferior frontal cortex (IFC) and the temporoparietal junction (TPJ) are involved in controlling imitation, but the functional roles of these areas remain unclear. Here, transcranial direct current stimulation (tDCS) was used to enhance cortical excitability at IFC and the TPJ prior to the completion of three tasks: (i) a naturalistic social interaction during which increased imitation is known to improve rapport, (ii) a choice reaction time task in which imitation needs to be inhibited for successful performance and (iii) a non-imitative control task. Relative to sham stimulation, stimulating IFC improved the context-dependent control of imitation—participants imitated more during the social interaction and less during the imitation inhibition task. In contrast, stimulating the TPJ reduced imitation in the inhibition task without affecting imitation during social interaction. Neither stimulation site affected the non-imitative control task. These data support a model in which IFC modulates imitation directly according to task demands, whereas TPJ controls task-appropriate shifts in attention toward representation of the self or the other, indirectly impacting upon imitation. PMID:25481003

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.

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.

Late administration of high-frequency electrical stimulation increases nerve regeneration without aggravating neuropathic pain in a nerve crush injury.

PubMed

Su, Hong-Lin; Chiang, Chien-Yi; Lu, Zong-Han; Cheng, Fu-Chou; Chen, Chun-Jung; Sheu, Meei-Ling; Sheehan, Jason; Pan, Hung-Chuan

2018-06-25

High-frequency transcutaneous neuromuscular electrical nerve stimulation (TENS) is currently used for the administration of electrical current in denervated muscle to alleviate muscle atrophy and enhance motor function; however, the time window (i.e. either immediate or delayed) for achieving benefit is still undetermined. In this study, we conducted an intervention of sciatic nerve crush injury using high-frequency TENS at different time points to assess the effect of motor and sensory functional recovery. Animals with left sciatic nerve crush injury received TENS treatment starting immediately after injury or 1 week later at a high frequency(100 Hz) or at a low frequency (2 Hz) as a control. In SFI gait analysis, either immediate or late admission of high-frequency electrical stimulation exerted significant improvement compared to either immediate or late administration of low-frequency electrical stimulation. In an assessment of allodynia, immediate high frequency electrical stimulation caused a significantly decreased pain threshold compared to late high-frequency or low-frequency stimulation at immediate or late time points. Immunohistochemistry staining and western blot analysis of S-100 and NF-200 demonstrated that both immediate and late high frequency electrical stimulation showed a similar effect; however the effect was superior to that achieved with low frequency stimulation. Immediate high frequency electrical stimulation resulted in significant expression of TNF-α and synaptophysin in the dorsal root ganglion, somatosensory cortex, and hippocampus compared to late electrical stimulation, and this trend paralleled the observed effect on somatosensory evoked potential. The CatWalk gait analysis also showed that immediate electrical stimulation led to a significantly high regularity index. In primary dorsal root ganglion cells culture, high-frequency electrical stimulation also exerted a significant increase in expression of TNF-α, synaptophysin, and NGF in accordance with the in vivo results. Immediate or late transcutaneous high-frequency electrical stimulation exhibited the potential to stimulate the motor nerve regeneration. However, immediate electrical stimulation had a predilection to develop neuropathic pain. A delay in TENS initiation appears to be a reasonable approach for nerve repair and provides the appropriate time profile for its clinical application.

Phase dependent modulation of tremor amplitude in essential tremor through thalamic stimulation

PubMed Central

Cagnan, Hayriye; Brittain, John-Stuart; Little, Simon; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Hariz, Marwan; Joint, Carole; Fitzgerald, James; Green, Alexander L.; Aziz, Tipu

2013-01-01

High frequency deep brain stimulation of the thalamus can help ameliorate severe essential tremor. Here we explore how the efficacy, efficiency and selectivity of thalamic deep brain stimulation might be improved in this condition. We started from the hypothesis that the effects of electrical stimulation on essential tremor may be phase dependent, and that, in particular, there are tremor phases at which stimuli preferentially lead to a reduction in the amplitude of tremor. The latter could be exploited to improve deep brain stimulation, particularly if tremor suppression could be reinforced by cumulative effects. Accordingly, we stimulated 10 patients with essential tremor and thalamic electrodes, while recording tremor amplitude and phase. Stimulation near the postural tremor frequency entrained tremor. Tremor amplitude was also modulated depending on the phase at which stimulation pulses were delivered in the tremor cycle. Stimuli in one half of the tremor cycle reduced median tremor amplitude by ∼10%, while those in the opposite half of the tremor cycle increased tremor amplitude by a similar amount. At optimal phase alignment tremor suppression reached 27%. Moreover, tremor amplitude showed a non-linear increase in the degree of suppression with successive stimuli; tremor suppression was increased threefold if a stimulus was preceded by four stimuli with a similar phase relationship with respect to the tremor, suggesting cumulative, possibly plastic, effects. The present results pave the way for a stimulation system that tracks tremor phase to control when deep brain stimulation pulses are delivered to treat essential tremor. This would allow treatment effects to be maximized by focussing stimulation on the optimal phase for suppression and by ensuring that this is repeated over many cycles so as to harness cumulative effects. Such a system might potentially achieve tremor control with far less power demand and greater specificity than current high frequency stimulation approaches, and may lower the risk for tolerance and rebound. PMID:24038075

Augmentation of spelling therapy with transcranial direct current stimulation in primary progressive aphasia: Preliminary results and challenges.

PubMed

Tsapkini, Kyrana; Frangakis, Constantine; Gomez, Yessenia; Davis, Cameron; Hillis, Argye E

Primary progressive aphasia (PPA) is a neurodegenerative disease that primarily affects language functions and often begins in the fifth or sixth decade of life. The devastating effects on work and family life call for the investigation of treatment alternatives. In this article, we present new data indicating that neuromodulatory treatment, using transcranial direct current stimulation (tDCS) combined with a spelling intervention, shows some promise for maintaining or even improving language, at least temporarily, in PPA. The main aim of the present article is to determine whether tDCS plus spelling intervention is more effective than spelling intervention alone in treating written language in PPA. We also asked whether the effects of tDCS are sustained longer than the effects of spelling intervention alone. We present data from six PPA participants who underwent anodal tDCS or sham plus spelling intervention in a within-subject crossover design. Each stimulation condition lasted 3 weeks or a total of 15 sessions with a 2-month interval in between. Participants were evaluated on treatment tasks as well as on other language and cognitive tasks at 2-week and 2-month follow-up intervals after each stimulation condition. All participants showed improvement in spelling (with sham or tDCS). There was no difference in the treated items between the two conditions. There was, however, consistent and significant improvement for untrained items only in the tDCS plus spelling intervention condition. Furthermore, the improvement lasted longer in the tDCS plus spelling intervention condition compared to sham plus spelling intervention condition. Neuromodulation with tDCS offers promise as a means of augmenting language therapy to improve written language function at least temporarily in PPA. The consistent finding of generalisation of treatment benefits to untreated items and the superior sustainability of treatment effects with tDCS justifies further investigations. However, the small sample size still requires caution in interpretation. Present interventions need to be optimised, and particular challenges, such as ways to account for the variable effect of degeneration in each individual, are discussed.

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.

Electrical resistivity measurements in the mammalian cochlea after neural degeneration.

PubMed

Micco, Alan G; Richter, Claus-Peter

2006-08-01

In the present series of experiments, the effect of neural degeneration on the cochlear structure electrical resistivities was evaluated to test if it alters the current flow in the cochlea and if increased current levels are needed to stimulate the impaired cochlea. In cochlear implants, frequency information is encoded in part by stimulating discrete populations of spiral ganglion cells along the cochlea. However, electrical properties of the cochlear structures result in shunting of the current away from the auditory neurons. This consumes energy, makes cochlear implants less efficient, and drastically reduces battery life. Models of the electrically stimulated cochlea serve to make predictions on current paths using modified and improved cochlear implant electrodes. However, one of the model's shortcomings is that most of the values for tissue impedances are not direct measurements. They are derived from bulk impedance measurements, which are fitted to lumped-element models. The four-electrode reflection-coefficient technique was used to measure resistivities in the gerbil cochlea. In vivo and in vitro (the hemicochlea) models were used. Measurements were made in normal and in deafened animals. Cochlear damage was induced by neomycin injection into the animals' middle ears. Neural degeneration was allowed to occur over 2 months before performing the measurements in the deafened animals. The resistivity values in deafened animals were smaller than in the normal-hearing animals, thus altering the current flow within the cochlea. Resistivity changes and subsequent changes in current path should be considered in future designs of cochlear implants.

Traditional and New Influenza Vaccines

PubMed Central

Wong, Sook-San

2013-01-01

SUMMARY The challenges in successful vaccination against influenza using conventional approaches lie in their variable efficacy in different age populations, the antigenic variability of the circulating virus, and the production and manufacturing limitations to ensure safe, timely, and adequate supply of vaccine. The conventional influenza vaccine platform is based on stimulating immunity against the major neutralizing antibody target, hemagglutinin (HA), by virus attenuation or inactivation. Improvements to this conventional system have focused primarily on improving production and immunogenicity. Cell culture, reverse genetics, and baculovirus expression technology allow for safe and scalable production, while adjuvants, dose variation, and alternate routes of delivery aim to improve vaccine immunogenicity. Fundamentally different approaches that are currently under development hope to signal new generations of influenza vaccines. Such approaches target nonvariable regions of antigenic proteins, with the idea of stimulating cross-protective antibodies and thus creating a “universal” influenza vaccine. While such approaches have obvious benefits, there are many hurdles yet to clear. Here, we discuss the process and challenges of the current influenza vaccine platform as well as new approaches that are being investigated based on the same antigenic target and newer technologies based on different antigenic targets. PMID:23824369

Scheduled, intermittent stimulation of the thalamus reduces tics in Tourette syndrome.

PubMed

Rossi, P Justin; Opri, Enrico; Shute, Jonathan B; Molina, Rene; Bowers, Dawn; Ward, Herbert; Foote, Kelly D; Gunduz, Aysegul; Okun, Michael S

2016-08-01

Personalized, scheduled deep brain stimulation in Tourette syndrome (TS) may permit clinically meaningful tic reduction while reducing side effects and increasing battery life. Here, we evaluate scheduled DBS applied to TS at two-year follow-up. Five patients underwent bilateral centromedian thalamic (CM) region DBS. A cranially contained constant-current device delivering stimulation on a scheduled duty cycle, as opposed to the standard continuous DBS paradigm was utilized. Baseline vs. 24-month outcomes were collected and analyzed, and a responder analysis was performed. A 40% improvement in the Modified Rush Tic Rating Scale (MRTRS) total score or Yale Global Tic Severity Scale (YGTSS) total score defined a full responder. Three of the 4 patients followed to 24 months reached full responder criteria and had a mean stimulation time of 1.85 h per day. One patient lost to follow-up evaluated at the last time point (month 18) was a non-responder. Patients exhibited improvements in MRTRS score beyond the improvements previously reported for the 6 month endpoint; on average, MRTRS total score was 15.6% better at 24 months than at 6 months and YGTSS total score was 14.8% better. Combining the patients into a single cohort revealed significant improvements in the MRTRS total score (-7.6 [5.64]; p = 0.02). Electrical stimulation of the centromedian thalamic region in a scheduled paradigm was effective in suppressing tics, particularly phonic tics. Full responders were able to achieve the positive DBS effect with a mean of 2.3 ± 0.9 (SEM) hours of DBS per day. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved proprioceptive function by application of subsensory electrical noise: Effects of aging and task-demand.

PubMed

Toledo, Diana R; Barela, José A; Kohn, André F

2017-09-01

The application of subsensory noise stimulation over the lower limbs has been shown to improve proprioception and postural control under certain conditions. Whereas the effect specificity seems to depend on several factors, studies are still needed to determine the appropriate method for training and rehabilitation purposes. In the current study, we investigated whether the application of subsensory electrical noise over the legs improves proprioceptive function in young and older adults. We aimed to provide evidence that stronger and age-related differential effects occur in more demanding tasks. Proprioceptive function was initially assessed by testing the detection of passive ankle movement (kinesthetic perception) in twenty-eight subjects (14 young and 14 older adults). Thereafter, postural control was assessed during tasks with different sensory challenges: i) by removing visual information (eyes closed) and; ii) by moving the visual scene (moving room paradigm). Tests performed with the application of electrical noise stimulation were compared to those performed without noise. The results showed that electrical noise applied over the legs led to a reduction in the response time to kinesthetic perception in both young and older adults. On the other hand, the magnitude of postural sway was reduced by noise stimulation only during a more challenging task, namely, when the optical flow was changing in an unpredictable (nonperiodic) manner. No differential effects of stimulation between groups were observed. These findings suggest that the relevance of proprioceptive inputs in tasks with different challenges, but not the subjects' age, is a determining factor for sensorimotor improvements due to electrical noise stimulation. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

The role of sleep quality and quantity in moderating the effectiveness of medication in the treatment of children with ADHD.

PubMed

Morash-Conway, Jessica; Gendron, Melissa; Corkum, Penny

2017-03-01

The current study examined: (1) whether long-acting stimulant medication is effective in improving performance on measures of memory, attention, and academic productivity; and (2) whether sleep impacts the relationship between medication and performance. Participants were 21 newly diagnosed, medication-naïve children (mean age = 9.1 years) with ADHD, who participated in a 4-week blinded placebo-controlled randomized trial of long-acting MPH. Participants underwent assessments of sleep (i.e., polysomnography) and of cognitive performance. Long-acting stimulant medication was found to be an effective treatment for enhancing alerting attention, executive attention, working memory, and academic productivity, but resulted in poorer sleep. Moreover, sleep duration was found to impact the treatment response to medication, in that longer sleep duration at baseline was related to improved executive attention. These results underscore the importance of evaluating and monitoring sleep when prescribing stimulant medication as a treatment for ADHD in children.

Capacitive Feedthroughs for Medical Implants

PubMed Central

Grob, Sven; Tass, Peter A.; Hauptmann, Christian

2016-01-01

Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

Capacitive Feedthroughs for Medical Implants.

PubMed

Grob, Sven; Tass, Peter A; Hauptmann, Christian

2016-01-01

Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

Leadership for School Improvement. Revised Edition.

ERIC Educational Resources Information Center

Mayeski, Fran; Gaddy, Barbara B.; Goodwin, Bryan

This monograph serves two purposes: (1) to stimulate further reflection and discussion among education leaders and policymakers to revitalize and strengthen the role that school leaders play in school reform; and (2) to assist researchers in identifying areas of future work. It synthesizes some of the most current literature pertinent to…

Thoracoscopic patch insulation to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy.

PubMed

Mediratta, Neeraj; Barker, Diane; McKevith, James; Davies, Peter; Belchambers, Sandra; Rao, Archana

2012-07-01

Cardiac resynchronization therapy is an established therapy for heart failure, improving quality of life and prognosis. Despite advances in technique, available leads and delivery systems, trans-venous left ventricular (LV) lead positioning remains dependent on the patient's underlying venous anatomy. The left phrenic nerve courses over the surface of the pericardium laterally and may be stimulated by the LV pacing lead, causing uncomfortable diaphragmatic twitch. This paper describes a video-assisted thoracoscopic (VATS) procedure to correct phrenic nerve stimulation secondary to cardiac resynchronization therapy. Most current ways of avoiding phrenic stimulation involve either electronic reprogramming to distance the phrenic nerve from the stimulation circuit or repositioning the lead. We describe a case where the phrenic nerve was surgically insulated from the stimulating current by insinuating a patch of bovine pericardium between the epicardium and native pericardium of the heart thus completely resolving previously intolerable and incessant diaphragmatic twitch. The procedure was performed under general anaesthesia with single-lung ventilation and minimal use of neuromuscular blocking agents. Surgical patch insulation of the phrenic nerve was performed using minimally invasive VATS surgery, as a short-stay procedure, with no complications. No diaphragmatic twitch occurred post-surgery and the patient continued to gain symptomatic benefit from cardiac synchronization therapy (New York Heart Association Class III to II), enabling return to work. In cases where the trans-venous position of a LV lead is limited by troublesome phrenic nerve stimulation, thoracoscopic surgical patch insulation of the phrenic nerve could be considered to allow beneficial cardiac resynchronization therapy.

Cross-axis adaptation improves 3D vestibulo-ocular reflex alignment during chronic stimulation via a head-mounted multichannel vestibular prosthesis

PubMed Central

Dai, Chenkai; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan; Melvin, Thuy-Anh; Cullen, Kathleen E.; Della Santina, Charles C.

2012-01-01

By sensing three-dimensional (3D) head rotation and electrically stimulating the three ampullary branches of a vestibular nerve to encode head angular velocity, a multichannel vestibular prosthesis (MVP) can restore vestibular sensation to individuals disabled by loss of vestibular hair cell function. However, current spread to afferent fibers innervating non-targeted canals and otolith endorgans can distort the vestibular nerve activation pattern, causing misalignment between the perceived and actual axis of head rotation. We hypothesized that over time, central neural mechanisms can adapt to correct this misalignment. To test this, we rendered five chinchillas vestibular-deficient via bilateral gentamicin treatment and unilaterally implanted them with a head mounted MVP. Comparison of 3D angular vestibulo-ocular reflex (aVOR) responses during 2 Hz, 50°/s peak horizontal sinusoidal head rotations in darkness on the first, third and seventh days of continual MVP use revealed that eye responses about the intended axis remained stable (at about 70% of the normal gain) while misalignment improved significantly by the end of one week of prosthetic stimulation. A comparable time course of improvement was also observed for head rotations about the other two semicircular canal axes and at every stimulus frequency examined (0.2–5 Hz). In addition, the extent of disconjugacy between the two eyes progressively improved during the same time window. These results indicate that the central nervous system rapidly adapts to multichannel prosthetic vestibular stimulation to markedly improve 3D aVOR alignment within the first week after activation. Similar adaptive improvements are likely to occur in other species, including humans. PMID:21374081

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

Recurrent themes in the history of the home use of electrical stimulation: Transcranial direct current stimulation (tDCS) and the medical battery (1870-1920).

PubMed

Wexler, Anna

In recent years, neuroscientists and ethicists have warned of the dangers of the unsupervised home use of transcranial direct current stimulation (tDCS), in which individuals stimulate their own brains with low levels of electricity for self-improvement purposes. Although the home use of tDCS is often referred to as a novel phenomenon, in reality the late nineteenth and early twentieth century saw a proliferation of electrical stimulation devices for home use. In particular, the use of an object known as the medical battery bears a number of striking similarities to the modern-day use of tDCS. This article reviews a number of features thought to be unique to the present day home use of brain stimulation, with a particular focus on analogies between tDCS and the medical battery. Archival research was conducted at the Bakken Museum and at the American Medical Association's Historical Health Fraud Archives. Many of the features characterizing the contemporary home use tDCS-a do-it-yourself (DIY) movement, anti-medical establishment themes, conflicts between lay and professional usage-are a repetition of themes that occurred a century ago with regard to the medical battery. A number of features, however, seem to be unique to the present, such as the dominant discourse about risk and safety, the division between cranial and non-cranial stimulation, and utilization for cognitive enhancement purposes. Viewed in the long durée, the contemporary use of electrical stimulation at home is not a novel phenomenon, but rather the latest wave in a series of ongoing attempts by lay individuals to utilize electricity for therapeutic purposes. Copyright © 2016 Elsevier Inc. All rights reserved.

Technical Rebuilding of Movement Function Using Functional Electrical Stimulation

NASA Astrophysics Data System (ADS)

Gföhler, Margit

To rebuild lost movement functions, neuroprostheses based on functional electrical stimulation (FES) artificially activate skeletal muscles in corresponding sequences, using both residual body functions and artificial signals for control. Besides the functional gain, FES training also brings physiological and psychological benefits for spinal cord-injured subjects. In this chapter, current stimulation technology and the main components of FES-based neuroprostheses including enhanced control systems are presented. Technology and application of FES cycling and rowing, both approaches that enable spinal cord-injured subjects to participate in mainstream activities and improve their health and fitness by exercising like able-bodied subjects, are discussed in detail, and an overview of neuroprostheses that aim at restoring movement functions for daily life as walking or grasping is given.

Transvertebral direct current stimulation paired with locomotor training in chronic spinal cord injury: A case study.

PubMed

Powell, Elizabeth Salmon; Carrico, Cheryl; Raithatha, Ravi; Salyers, Emily; Ward, Andrea; Sawaki, Lumy

2016-01-01

This double-blind, sham-controlled, crossover case study combined transvertebral direct current stimulation (tvDCS) and locomotor training on a robot-assisted gait orthosis (LT-RGO). Determine whether cathodal tvDCS paired with LT-RGO leads to greater changes in function and neuroplasticity than sham tvDCS paired with LT-RGO. University of Kentucky (UK) HealthCare Stroke and Spinal Cord Neurorehabilitation Research at HealthSouth Cardinal Hill Hospital. A single subject with motor incomplete spinal cord injury (SCI) participated in 24 sessions of sham tvDCS paired with LT-RGO before crossover to 24 sessions of cathodal tvDCS paired with LT-RGO. Functional outcomes were measured with 10 Meter Walk Test (10MWT), 6 Minute Walk Test (6MWT), Spinal Cord Independence Measure-III (SCIM-III) mobility component, lower extremity manual muscle test (MMT), and Berg Balance Scale (BBS). Corticospinal changes were assessed using transcranial magnetic stimulation. Improvement in 10MWT speed, SCIM-III mobility component, and BBS occurred with both conditions. 6MWT worsened after sham tvDCS and improved after cathodal tvDCS. MMT scores for both lower extremities improved following sham tvDCS but decreased following cathodal tvDCS. Corticospinal excitability increased following cathodal tvDCS but not sham tvDCS. These results suggest that combining cathodal tvDCS and LT-RGO may improve functional outcomes, increase corticospinal excitability, and possibly decrease spasticity. Randomized controlled trials are needed to confirm these conclusions. This publication was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1TR000117, and the HealthSouth Cardinal Hill Stroke and Spinal Cord Endowment (1215375670).

Noninvasive Brain Stimulation in Pediatric Attention-Deficit Hyperactivity Disorder (ADHD): A Review.

PubMed

Rubio, Belen; Boes, Aaron D; Laganiere, Simon; Rotenberg, Alexander; Jeurissen, Danique; Pascual-Leone, Alvaro

2016-05-01

Attention-deficit hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in the pediatric population. The clinical management of ADHD is currently limited by a lack of reliable diagnostic biomarkers and inadequate therapy for a minority of patients who do not respond to standard pharmacotherapy. There is optimism that noninvasive brain stimulation may help to address these limitations. Transcranial magnetic stimulation and transcranial direct current stimulation are 2 methods of noninvasive brain stimulation that modulate cortical excitability and brain network activity. Transcranial magnetic stimulation can be used diagnostically to probe cortical neurophysiology, whereas daily use of repetitive transcranial magnetic stimulation or transcranial direct current stimulation can induce long-lasting and potentially therapeutic changes in targeted networks. In this review, we highlight research showing the potential diagnostic and therapeutic applications of transcranial magnetic stimulation and transcranial direct current stimulation in pediatric ADHD. We also discuss the safety and ethics of using these tools in the pediatric population. © The Author(s) 2015.

Determining which mechanisms lead to activation in the motor cortex: a modeling study of transcranial magnetic stimulation using realistic stimulus waveforms and sulcal geometry1

PubMed Central

Salvador, R.; Silva, S.; Basser, P. J.; Miranda, P. C.

2010-01-01

Objective To determine which mechanisms lead to activation of neurons in the motor cortex during transcranial magnetic stimulation (TMS) with different current directions and pulse waveforms. Methods The total electric field induced in a simplified model of a cortical sulcus by a figure-eight coil was calculated using the finite element method (FEM). This electric field was then used as the input to determine the response of compartmental models of several types of neurons. Results The modeled neurons were stimulated at different sites: fiber bends for pyramidal tract neurons, axonal terminations for cortical interneurons and axon collaterals, and a combination of both for pyramidal association fibers. All neurons were more easily stimulated by a PA directed electric field, except association fibers. Additionally, the second phase of a biphasic pulse was found to be more efficient than the first phase of either monophasic or biphasic pulses. Conclusion The stimulation threshold for different types of neurons depends on the pulse waveform and current direction. The reported results might account for the range of responses obtained in TMS of the motor cortex when using different stimulation parameters. Significance Modeling studies combining electric field calculations and neuronal models may lead to a deeper understanding of the effect of the TMS-induced electric field on cortical tissue, and may be used to evaluate improvements in TMS coil and waveform design. PMID:21035390

Determine Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function

NASA Technical Reports Server (NTRS)

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J.J.;

Effects of Anodal Transcranial Direct Current Stimulation and Serotonergic Enhancement on Memory Performance in Young and Older Adults.

PubMed

Prehn, Kristin; Stengl, Helena; Grittner, Ulrike; Kosiolek, René; Ölschläger, Anja; Weidemann, Alexandra; Flöel, Agnes

2017-01-01

In the absence of effective therapies for dementia and its precursors, enhancing neuroplasticity by means of non-invasive brain stimulation such as anodal transcranial direct current stimulation (atDCS) might be a promising approach to counteract or delay the onset of cognitive decline, but effect sizes have been moderate so far. Previous reports indicate that increasing serotonin levels may enhance atDCS-induced neuroplasticity. However, evidence for serotonergic modulation of atDCS effects on memory is still lacking. Here, we conducted a double-blind, randomized, sham-/placebo-controlled trial to investigate the impact of a selective serotonin reuptake inhibitor (SSRI; single dose of 20 mg citalopram) and atDCS over the right temporoparietal cortex (1 mA, 20 min) on memory formation. Twenty young and 20 older subjects completed an object-location learning task in each of the four conditions: sham+placebo, sham+SSRI, atDCS+placebo, and atDCS+SSRI. Outcome measures were performance in immediate (primary outcome) and delayed cued recall. While we found an SSRI effect, but no statistically significant effect of atDCS on immediate recall scores, young and older adults benefited most from the combined application (comparisons: atDCS+SSRI>atDCS+placebo and atDCS+SSRI>sham+placebo). Thus, our data provide evidence that atDCS improves memory formation if serotonergic neurotransmission is enhanced simultaneously. Further studies are needed to assess whether these findings extend to clinical populations with memory impairment and translate into clinically relevant improvements after long-term serotonergic enhancement and repeated stimulation.

Effects of Anodal Transcranial Direct Current Stimulation and Serotonergic Enhancement on Memory Performance in Young and Older Adults

PubMed Central

Prehn, Kristin; Stengl, Helena; Grittner, Ulrike; Kosiolek, René; Ölschläger, Anja; Weidemann, Alexandra; Flöel, Agnes

2017-01-01

In the absence of effective therapies for dementia and its precursors, enhancing neuroplasticity by means of non-invasive brain stimulation such as anodal transcranial direct current stimulation (atDCS) might be a promising approach to counteract or delay the onset of cognitive decline, but effect sizes have been moderate so far. Previous reports indicate that increasing serotonin levels may enhance atDCS-induced neuroplasticity. However, evidence for serotonergic modulation of atDCS effects on memory is still lacking. Here, we conducted a double-blind, randomized, sham-/placebo-controlled trial to investigate the impact of a selective serotonin reuptake inhibitor (SSRI; single dose of 20 mg citalopram) and atDCS over the right temporoparietal cortex (1 mA, 20 min) on memory formation. Twenty young and 20 older subjects completed an object-location learning task in each of the four conditions: sham+placebo, sham+SSRI, atDCS+placebo, and atDCS+SSRI. Outcome measures were performance in immediate (primary outcome) and delayed cued recall. While we found an SSRI effect, but no statistically significant effect of atDCS on immediate recall scores, young and older adults benefited most from the combined application (comparisons: atDCS+SSRI>atDCS+placebo and atDCS+SSRI>sham+placebo). Thus, our data provide evidence that atDCS improves memory formation if serotonergic neurotransmission is enhanced simultaneously. Further studies are needed to assess whether these findings extend to clinical populations with memory impairment and translate into clinically relevant improvements after long-term serotonergic enhancement and repeated stimulation. PMID:27555381

Fatigue reduction during aggregated and distributed sequential stimulation.

PubMed

Bergquist, Austin J; Babbar, Vishvek; Ali, Saima; Popovic, Milos R; Masani, Kei

2017-08-01

Transcutaneous neuromuscular electrical stimulation (NMES) can generate muscle contractions for rehabilitation and exercise. However, NMES-evoked contractions are limited by fatigue when they are delivered "conventionally" (CONV) using a single active electrode. Researchers have developed "sequential" (SEQ) stimulation, involving rotation of pulses between multiple "aggregated" (AGGR-SEQ) or "distributed" (DISTR-SEQ) active electrodes, to reduce fatigue (torque-decline) by reducing motor unit discharge rates. The primary objective was to compare fatigue-related outcomes, "potentiation," "variability," and "efficiency" between CONV, AGGR-SEQ, and DISTR-SEQ stimulation of knee extensors in healthy participants. Torque and current were recorded during testing with fatiguing trains using each NMES type under isometric and isokinetic (180°/s) conditions. Compared with CONV stimulation, SEQ techniques reduced fatigue-related outcomes, increased potentiation, did not affect variability, and reduced efficiency. SEQ techniques hold promise for reducing fatigue during NMES-based rehabilitation and exercise; however, optimization is required to improve efficiency. Muscle Nerve 56: 271-281, 2017. © 2016 Wiley Periodicals, Inc.

Mechanism of orientation of stimulating currents in magnetic brain stimulation (abstract)

NASA Astrophysics Data System (ADS)

Ueno, S.; Matsuda, T.

1991-04-01

We made a functional map of the human motor cortex related to the hand and foot areas by stimulating the human brain with a focused magnetic pulse. We observed that each functional area in the cortex has an optimum direction for which stimulating currents can produce neural excitation. The present report focuses on the mechanism which is responsible for producing this anisotropic response to brain stimulation. We first obtained a functional map of the brain related to the left ADM (abductor digiti minimi muscles). When the stimulating currents were aligned in the direction from the left to the right hemisphere, clear EMG (electromyographic) responses were obtained only from the left ADM to magnetic stimulation of both hemisphere. When the stimulating currents were aligned in the direction from the right to the left hemisphere, clear EMG signals were obtained only from the right ADM to magnetic stimulation of both hemisphere. The functional maps of the brain were sensitive to changes in the direction of the stimulating currents. To explain the phenomena obtained in the experiments, we developed a model of neural excitation elicited by magnetic stimulation. When eddy currents which are induced by pulsed magnetic fields flow in the direction from soma to the distal part of neural fiber, depolarized area in the distal part are excited, and the membrane excitation propagates along the nerve fiber. In contrast, when the induced currents flow in the direction from the distal part to soma, hyperpolarized parts block or inhibit neural excitation even if the depolarized parts near the soma can be excited. The model explains our observation that the orientation of the induced current vectors reflect both the functional and anatomical organization of the neural fibers in the brain.

Non-invasive electric current stimulation for restoration of vision after unilateral occipital stroke.

PubMed

Gall, Carolin; Silvennoinen, Katri; Granata, Giuseppe; de Rossi, Francesca; Vecchio, Fabrizio; Brösel, Doreen; Bola, Michał; Sailer, Michael; Waleszczyk, Wioletta J; Rossini, Paolo M; Tatlisumak, Turgut; Sabel, Bernhard A

2015-07-01

Occipital stroke often leads to visual field loss, for which no effective treatment exists. Little is known about the potential of non-invasive electric current stimulation to ameliorate visual functions in patients suffering from unilateral occipital stroke. One reason is the traditional thinking that visual field loss after brain lesions is permanent. Since evidence is available documenting vision restoration by means of vision training or non-invasive electric current stimulation future studies should also consider investigating recovery processes after visual cortical strokes. Here, protocols of repetitive transorbital alternating current stimulation (rtACS) and transcranial direct current stimulation (tDCS) are presented and the European consortium for restoration of vision (REVIS) is introduced. Within the consortium different stimulation approaches will be applied to patients with unilateral occipital strokes resulting in homonymous hemianopic visual field defects. The aim of the study is to evaluate effects of current stimulation of the brain on vision parameters, vision-related quality of life, and physiological parameters that allow concluding about the mechanisms of vision restoration. These include EEG-spectra and coherence measures, and visual evoked potentials. The design of stimulation protocols involves an appropriate sham-stimulation condition and sufficient follow-up periods to test whether the effects are stable. This is the first application of non-invasive current stimulation for vision rehabilitation in stroke-related visual field deficits. Positive results of the trials could have far-reaching implications for clinical practice. The ability of non-invasive electrical current brain stimulation to modulate the activity of neuronal networks may have implications for stroke rehabilitation also in the visual domain. Copyright © 2015 Elsevier Inc. All rights reserved.

[Repetitive transcranial magnetic stimulation: A potential therapy for cognitive disorders?

PubMed

Nouhaud, C; Sherrard, R M; Belmin, J

2017-03-01

Considering the limited effectiveness of drugs treatments in cognitive disorders, the emergence of noninvasive techniques to modify brain function is very interesting. Among these techniques, repetitive transcranial magnetic stimulation (rTMS) can modulate cortical excitability and have potential therapeutic effects on cognition and behaviour. These effects are due to physiological modifications in the stimulated cortical tissue and their associated circuits, which depend on the parameters of stimulation. The objective of this article is to specify current knowledge and efficacy of rTMS in cognitive disorders. Previous studies found very encouraging results with significant improvement of higher brain functions. Nevertheless, these few studies have limits: a few patients were enrolled, the lack of control of the mechanisms of action by brain imaging, insufficiently formalized technique and variability of cognitive tests. It is therefore necessary to perform more studies, which identify statistical significant improvement and to specify underlying mechanisms of action and the parameters of use of the rTMS to offer rTMS as a routine therapy for cognitive dysfunction. Copyright © 2016 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.

Effects of functional electrical stimulation on gait recovery post-neurological injury during inpatient rehabilitation.

PubMed

Lairamore, Chad I; Garrison, Mark K; Bourgeon, Laetitia; Mennemeier, Mark

2014-10-01

This stage 2 trial investigated the therapeutic effect of single channel, peroneal functional electrical stimulation (FES) for improving gait and muscle activity in people with neurological injuries who were enrolled in an inpatient rehabilitation program. Twenty-six patients (16 male; M age = 51.3 yr., SD = 16.2; 2-33 days post-injury) completed the study. Participants were randomly assigned to an experimental group (n = 13) or control group (n = 13). The experimental group received FES and the control group received sensory stimulation during 45-min. gait training sessions three times a week for the duration of their stay in a rehabilitation facility (average of four sessions for both groups). Changes in gait speed, tibialis anterior muscle electromyography (EMG), and FIM™ locomotion scores were compared between groups. No significant differences were found, as both groups demonstrated similar improvements. The current results with this small sample suggest a low dose of gait training with single channel FES did not augment gait nor EMG activity beyond gait training with sensory stimulation; therefore, clinicians will likely be better served using a larger dose of FES or multichannel FES in this clinical population.

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

DTIC Science & Technology

2015-03-01

AFRL-RH-WP-TR-2015-0013 Augmenting Visual Search Performance with transcranial Direct Current Stimulation ( tDCS ) Justin Nelson...Stimulation ( tDCS ) 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Justin Nelson‡, Dr. R. Andy McKinley...evaluate a form of non-invasive brain stimulation known as transcranial direct current stimulation ( tDCS ) over the left frontal eye field (LFEF) region

Noninvasive brain stimulation to suppress craving in substance use disorders: review of human evidence and methodological considerations for future work

PubMed Central

Hone-Blanchet, Antoine; Ciraulo, Domenic A; Pascual-Leone, Alvaro; Fecteau, Shirley

2016-01-01

Substance use disorders (SUDs) can be viewed as a pathology of neuroadaptation. The pharmacological overstimulation of neural mechanisms of reward, motivated learning and memory leads to drug-seeking behavior. A critical characteristic of SUDs is the appearance of craving, the motivated desire and urge to use, which is a main focus of current pharmacological and behavioral therapies. Recent proof-of-concept studies have tested the effects of non-invasive brain stimulation on craving. Although its mechanisms of action are not fully understood, this approach shows interesting potential in tuning down craving and possibly consumption of diverse substances. This article reviews available results on the use of repetitive transcranial magnetic stimulation (rTMS) and transcranial electrical stimulation (tES) in SUDs, specifically tobacco, alcohol and psychostimulant use disorders. We discuss several important factors that need to be addressed in future works to improve clinical assessment and effects of non-invasive brain stimulation in SUDs. Factors discussed include brain stimulation devices and parameters, study designs, brain states and subjects’ characteristics. PMID:26449761

Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome (CRPS) Recurrence after Amputation for CRPS, and Failure of Conventional Spinal Cord Stimulation.

PubMed

Goebel, Andreas; Lewis, Sarah; Phillip, Rhodri; Sharma, Manohar

2018-01-01

Limb amputation is sometimes being performed in long-standing complex regional pain syndrome (CRPS), although little evidence is available guiding management decisions, including how CRPS recurrence should be managed. This report details the management of a young soldier with CRPS recurrence 2 years after midtibial amputation for CRPS. Conventional spinal cord stimulation did not achieve paraesthetic coverage, or pain relief in the stump, whereas L4 dorsal root ganglion stimulation achieved both coverage and initially modest pain relief, and over time, substantial pain relief. Current evidence does not support the use of amputation to improve either pain or function in CRPS. Before a decision is made, in exceptional cases, about referral for amputation, dorsal root ganglion stimulation should be considered as a potentially effective treatment, even where conventional spinal cord stimulator treatment has failed to achieve reliable paraesthetic cover. Furthermore, this treatment may provide pain relief in those patients with CRPS recurrence in the stump after amputation. © 2017 World Institute of Pain.

A Dual Mode Pulsed Electro-Magnetic Cell Stimulator Produces Acceleration of Myogenic Differentiation

PubMed Central

Leon-Salas, Walter D.; Rizk, Hatem; Mo, Chenglin; Weisleder, Noah; Brotto, Leticia; Abreu, Eduardo; Brotto, Marco

2013-01-01

This paper presents the design and test of a dual-mode electric and magnetic biological stimulator (EM-Stim). The stimulator generates pulsing electric and magnetic fields at programmable rates and intensities. While electric and magnetic stimulators have been reported before, this is the first device that combines both modalities. The ability of the dual stimulation to target bone and muscle tissue simultaneously has the potential to improve the therapeutic treatment of osteoporosis and sarcopenia. The device is fully programmable, portable and easy to use, and can run from a battery or a power supply. The device can generate magnetic fields of up to 1.6 mT and output voltages of +/−40 V. The EM-Stim accelerated myogenic differentiation of myoblasts into myotubes as evidenced by morphometric, gene expression, and protein content analyses. Currently, there are many patents concerned with the application of single electrical or magnetic stimulation, but none that combine both simultaneously. However, we applied for and obtained a provisional patent for new device to fully explore its therapeutic potential in pre-clinical models. PMID:23445453

A dual mode pulsed electro-magnetic cell stimulator produces acceleration of myogenic differentiation.

PubMed

Leon-Salas, Walter D; Rizk, Hatem; Mo, Chenglin; Weisleder, Noah; Brotto, Leticia; Abreu, Eduardo; Brotto, Marco

2013-04-01

This paper presents the design and test of a dual-mode electric and magnetic biological stimulator (EM-Stim). The stimulator generates pulsing electric and magnetic fields at programmable rates and intensities. While electric and magnetic stimulators have been reported before, this is the first device that combines both modalities. The ability of the dual stimulation to target bone and muscle tissue simultaneously has the potential to improve the therapeutic treatment of osteoporosis and sarcopenia. The device is fully programmable, portable and easy to use, and can run from a battery or a power supply. The device can generate magnetic fields of up to 1.6 mT and output voltages of +/- 40 V. The EM-Stim accelerated myogenic differentiation of myoblasts into myotubes as evidenced by morphometric, gene expression, and protein content analyses. Currently, there are many patents concerned with the application of single electrical or magnetic stimulation, but none that combine both simultaneously. However, we applied for and obtained a provisional patent for new device to fully explore its therapeutic potential in pre-clinical models.

Noninvasive brain stimulation to suppress craving in substance use disorders: Review of human evidence and methodological considerations for future work.

PubMed

Hone-Blanchet, Antoine; Ciraulo, Domenic A; Pascual-Leone, Alvaro; Fecteau, Shirley

2015-12-01

Substance use disorders (SUDs) can be viewed as a pathology of neuroadaptation. The pharmacological overstimulation of neural mechanisms of reward, motivated learning and memory leads to drug-seeking behavior. A critical characteristic of SUDs is the appearance of craving, the motivated desire and urge to use, which is a main focus of current pharmacological and behavioral therapies. Recent proof-of-concept studies have tested the effects of noninvasive brain stimulation on craving. Although its mechanisms of action are not fully understood, this approach shows interesting potential in tuning down craving and possibly consumption of diverse substances. This article reviews available results on the use of repetitive transcranial magnetic stimulation (rTMS) and transcranial electrical stimulation (tES) in SUDs, specifically tobacco, alcohol and psychostimulant use disorders. We discuss several important factors that need to be addressed in future works to improve clinical assessment and effects of noninvasive brain stimulation in SUDs. Factors discussed include brain stimulation devices and parameters, study designs, brain states and subjects' characteristics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Non-invasive brain stimulation in neurorehabilitation: local and distant effects for motor recovery

PubMed Central

Liew, Sook-Lei; Santarnecchi, Emilliano; Buch, Ethan R.; Cohen, Leonardo G.

2014-01-01

Non-invasive brain stimulation (NIBS) may enhance motor recovery after neurological injury through the causal induction of plasticity processes. Neurological injury, such as stroke, often results in serious long-term physical disabilities, and despite intensive therapy, a large majority of brain injury survivors fail to regain full motor function. Emerging research suggests that NIBS techniques, such as transcranial magnetic (TMS) and direct current (tDCS) stimulation, in association with customarily used neurorehabilitative treatments, may enhance motor recovery. This paper provides a general review on TMS and tDCS paradigms, the mechanisms by which they operate and the stimulation techniques used in neurorehabilitation, specifically stroke. TMS and tDCS influence regional neural activity underlying the stimulation location and also distant interconnected network activity throughout the brain. We discuss recent studies that document NIBS effects on global brain activity measured with various neuroimaging techniques, which help to characterize better strategies for more accurate NIBS stimulation. These rapidly growing areas of inquiry may hold potential for improving the effectiveness of NIBS-based interventions for clinical rehabilitation. PMID:25018714

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.

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 complexity of normal and pathological brain function, and how recent studies have already indicated more sophisticated approaches are necessary. One tDCS theory regarding "functional targeting" suggests the specificity of tDCS effects are possible by modulating ongoing function (plasticity). Use of animal models of disease are summarized including pain, movement disorders, stroke, and epilepsy. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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 complexity of normal and pathological brain function, and how recent studies have already indicated more sophisticated approaches are necessary. One tDCS theory regarding “functional targeting” suggests the specificity of tDCS effects are possible by modulating ongoing function (plasticity). Use of animal models of disease are summarized including pain, movement disorders, stroke, and epilepsy. PMID:27693941

Assessment of MSFCs Process for the Development and Activation of Space Act Agreement

NASA Technical Reports Server (NTRS)

Daugherty, Rachel

2014-01-01

Space Act Agreements (SAAs) are contractual agreements that NASA utilizes to form partnerships with researchers, industry, and academia to stimulate cutting-edge innovation within the science and technology communities. center dot This study assessed the current SAA development and activation process at Marshall Space Flight Center (MSFC) to determine if improvements could be implemented to increase productivity, decrease time to activation, and improve the quality of deliverables.

Binding oneself to the mast: stimulating frontopolar cortex enhances precommitment

PubMed Central

Ugazio, Giuseppe; Crockett, Molly J.; Ruff, Christian C.; Kalenscher, Tobias; Tobler, Philippe N.

2017-01-01

Abstract Humans often give in to temptations that are in conflict with valuable long-term goals like health or saving for the future. Such willpower failures represent a prevalent problem in everyday life and in many psychiatric disorders. Strategies that increase resistance to temptations could therefore improve overall societal well-being. One important strategy is to voluntarily precommit, i.e. to restrict one’s future action space by removing the tempting short-term option from the choice set, thereby leaving only the long-term option for implementation. The neural mechanisms necessary to implement precommitment have remained unknown. Here, we test whether anodal transcranial direct current stimulation (tDCS) over the frontopolar cortex (FPC) can improve precommitment. Participants performed a self-control task in which they could precommit to obtain a delayed larger reward by removing an immediately available smaller reward from the future choice options. We found that anodal stimulation over FPC selectively increased the propensity to precommit. In contrast, tDCS had no effects on non-binding decisions, impulse control or reward preference. Our data establish a causal role for the FPC in the implementation of precommitment, revealing a novel route to improving resistance against temptations. PMID:28170049

Technological Advances in Deep Brain Stimulation.

PubMed

Ughratdar, Ismail; Samuel, Michael; Ashkan, Keyoumars

2015-01-01

Functional and stereotactic neurosurgery has always been regarded as a subspecialty based on and driven by technological advances. However until recently, the fundamentals of deep brain stimulation (DBS) hardware and software design had largely remained stagnant since its inception almost three decades ago. Recent improved understanding of disease processes in movement disorders as well clinician and patient demands has resulted in new avenues of development for DBS technology. This review describes new advances both related to hardware and software for neuromodulation. New electrode designs with segmented contacts now enable sophisticated shaping and sculpting of the field of stimulation, potentially allowing multi-target stimulation and avoidance of side effects. To avoid lengthy programming sessions utilising multiple lead contacts, new user-friendly software allows for computational modelling and individualised directed programming. Therapy delivery is being improved with the next generation of smaller profile, longer-lasting, re-chargeable implantable pulse generators (IPGs). These include IPGs capable of delivering constant current stimulation or personalised closed-loop adaptive stimulation. Post-implantation Magnetic Resonance Imaging (MRI) has long been an issue which has been partially overcome with 'MRI conditional devices' and has enabled verification of DBS lead location. Surgical technique is considering a shift from frame-based to frameless stereotaxy or greater role for robot assisted implantation. The challenge for these contemporary techniques however, will be in demonstrating equivalent safety and accuracy to conventional methods. We also discuss potential future direction utilising wireless technology allowing for miniaturisation of hardware.

Electrical Stimulation and Cutaneous Wound Healing: A Review of Clinical Evidence

PubMed Central

Ud-Din, Sara; Bayat, Ardeshir

2014-01-01

Electrical stimulation (ES) has been shown to have beneficial effects in wound healing. It is important to assess the effects of ES on cutaneous wound healing in order to ensure optimization for clinical practice. Several different applications as well as modalities of ES have been described, including direct current (DC), alternating current (AC), high-voltage pulsed current (HVPC), low-intensity direct current (LIDC) and electrobiofeedback ES. However, no one method has been advocated as the most optimal for the treatment of cutaneous wound healing. Therefore, this review aims to examine the level of evidence (LOE) for the application of different types of ES to enhance cutaneous wound healing in the skin. An extensive search was conducted to identify relevant clinical studies utilising ES for cutaneous wound healing since 1980 using PubMed, Medline and EMBASE. A total of 48 studies were evaluated and assigned LOE. All types of ES demonstrated positive effects on cutaneous wound healing in the majority of studies. However, the reported studies demonstrate contrasting differences in the parameters and types of ES application, leading to an inability to generate sufficient evidence to support any one standard therapeutic approach. Despite variations in the type of current, duration, and dosing of ES, the majority of studies showed a significant improvement in wound area reduction or accelerated wound healing compared to the standard of care or sham therapy as well as improved local perfusion. The limited number of LOE-1 trials for investigating the effects of ES in wound healing make critical evaluation and assessment somewhat difficult. Further, better-designed clinical trials are needed to improve our understanding of the optimal dosing, timing and type of ES to be used. PMID:27429287

Optimal Stimulus Amplitude for Vestibular Stochastic Stimulation to Improve Sensorimotor Function

NASA Technical Reports Server (NTRS)

Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J. J.;

Electrical brain stimulation (tES) improves learning more than performance: A meta-analysis.

PubMed

Simonsmeier, Bianca A; Grabner, Roland H; Hein, Julia; Krenz, Ugne; Schneider, Michael

2018-01-01

Researchers have recently started evaluating whether stimulating the brain noninvasively with a weak and painless electrical current (transcranial Electrical Stimulation, tES) enhances physiological and cognitive processes. Some studies found that tES has weak but positive effects on brain physiology, cognition, or assessment performance, which has attracted massive public interest. We present the first meta-analytic test of the hypothesis that tES in a learning phase is more effective than tES in an assessment phase. The meta-analysis included 246 effect sizes from studies on language or mathematical competence. The effect of tES was stronger when stimulation was administered during a learning phase (d=0.712) as compared to stimulation administered during test performance (d=0.207). The overall effect was stimulation-dosage specific and, as found in a previous meta-analysis, significant only for anodal stimulation and not for cathodal. The results provide evidence for the modulation of long-term synaptic plasticity by tES in the context of practically relevant learning tasks and highlight the need for more systematic evaluations of tES in educational settings. Copyright © 2017 Elsevier 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 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

Cognitive control dysfunction in emotion dysregulation and psychopathology of major depression (MD): Evidence from transcranial brain stimulation of the dorsolateral prefrontal cortex (DLPFC).

PubMed

Salehinejad, Mohammad Ali; Ghanavai, Elham; Rostami, Reza; Nejati, Vahid

2017-03-01

Previous studies showed that MD is associated with a variety of cognitive deficits and executive dysfunctions which can persist even in remitted states. However, the role of cognitive impairments in MD psychopathology and treatment is not fully understood. This article aims to discuss how executive functions central components (e.g., Working memory and attention) mediate MD psychopathology considering the role of dorsolateral prefrontal cortex (dLPFC) and present findings of a brain stimulation experiment to support this notion. The effect of transcranial direct current stimulation (tDCS) of the dLPFC on enhancing cognitive control functions was investigated. Twenty-four patients with MD (Experimental group=12, Control group=12) received 10 sessions of tDCS (2mA for 30min) over 10 consecutive days. The experimental group received active stimulation and the control group received sham stimulation. Participant's performance on cognitive functions (PAL, SRM, RVP and CRT from CANTAB) and their depression scores were assessed before and after tDCS. Results showed that brain stimulation of the dLPFC improved executive dysfunction in patients and a significant improvement on depression scores was also observed suggesting that cognitive control dysfunction may be a mediator in emotional dysregulation and psychopathology of MD. No follow-up investigation was done in this study which does not allow to infer long-term effect of tDCS. Low-focality of tDCS might have stimulated adjacent areas too. Cognitive components, namely cognitive control dysfunction, play role in MD psychopathology as they are involved in emotion dysregulation in MD. The amount of contribution of cognitive components in MD psychopathology is however, an open question. tDCS can be used as an intervention to improve cognitive dysfunction in MD. Copyright © 2017 Elsevier B.V. All rights reserved.

An efficient 3-D eddy-current solver using an independent impedance method for transcranial magnetic stimulation.

PubMed

De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc

2011-02-01

In many important bioelectromagnetic problem settings, eddy-current simulations are required. Examples are the reduction of eddy-current artifacts in magnetic resonance imaging and techniques, whereby the eddy currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the eddy currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the eddy-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations.

Blood doping: risks to athletes' health and strategies for detection.

PubMed

Oliveira, Carolina Dizioli Rodrigues de; Bairros, André Valle de; Yonamine, Mauricio

2014-07-01

Blood doping has been defined as the misuse of substances or certain techniques to optimize oxygen delivery to muscles with the aim to increase performance in sports activities. It includes blood transfusion, administration of erythropoiesis-stimulating agents or blood substitutes, and gene manipulations. The main reasons for the widespread use of blood doping include: its availability for athletes (erythropoiesis-stimulating agents and blood transfusions), its efficiency in improving performance, and its difficult detection. This article reviews and discusses the blood doping substances and methods used for in sports, the adverse effects related to this practice, and current strategies for its detection.

The Evolution of Neuroprosthetic Interfaces

PubMed Central

Adewole, Dayo O.; Serruya, Mijail D.; Harris, James P.; Burrell, Justin C.; Petrov, Dmitriy; Chen, H. Isaac; Wolf, John A.; Cullen, D. Kacy

2017-01-01

The ideal neuroprosthetic interface permits high-quality neural recording and stimulation of the nervous system while reliably providing clinical benefits over chronic periods. Although current technologies have made notable strides in this direction, significant improvements must be made to better achieve these design goals and satisfy clinical needs. This article provides an overview of the state of neuroprosthetic interfaces, starting with the design and placement of these interfaces before exploring the stimulation and recording platforms yielded from contemporary research. Finally, we outline emerging research trends in an effort to explore the potential next generation of neuroprosthetic interfaces. PMID:27652455

A Resource Center for the Stimulation of Post Secondary Education Innovation via Computer Network.

ERIC Educational Resources Information Center

Savin, William

The goal of the project described here was to improve the quality of postsecondary education by offering institutions of higher learning information on currently funded educational projects through an interactive database, the Educational Resources Directory (ERD), which contains information on new methods, curricula, and educational technology.…

A Curriculum Program for Infants Six to Twelve Months.

ERIC Educational Resources Information Center

Dickinson, Barbara Gibello

This curriculum program was developed to serve as a guide or reference for those professionals wishing to implement or improve upon a current participation program for parents of 6- to 12-month-old infants. The curriculum program covers such topics as the importance of early stimulation, infants' gross and fine motor development, social/emotional…

Student Proficiency in Spanish Taught by Native and Nonnative Spanish Instructors: A Quantitative Correlational Study

ERIC Educational Resources Information Center

Kopczynski, Karolina

2010-01-01

Foreign language educators as well as educators from other disciplines agree that learning any foreign language improves student language skills and stimulates creative thinking and flexibility to use the language. The purpose of the current quantitative, correlational study was to examine the relationship between student proficiency in Spanish…

Universal Vaccines and Vaccine Platforms to Protect against Influenza Viruses in Humans and Agriculture

PubMed Central

Rajão, Daniela S.; Pérez, Daniel R.

2018-01-01

Influenza virus infections pose a significant threat to public health due to annual seasonal epidemics and occasional pandemics. Influenza is also associated with significant economic losses in animal production. The most effective way to prevent influenza infections is through vaccination. Current vaccine programs rely heavily on the vaccine's ability to stimulate neutralizing antibody responses to the hemagglutinin (HA) protein. One of the biggest challenges to an effective vaccination program lies on the fact that influenza viruses are ever-changing, leading to antigenic drift that results in escape from earlier immune responses. Efforts toward overcoming these challenges aim at improving the strength and/or breadth of the immune response. Novel vaccine technologies, the so-called universal vaccines, focus on stimulating better cross-protection against many or all influenza strains. However, vaccine platforms or manufacturing technologies being tested to improve vaccine efficacy are heterogeneous between different species and/or either tailored for epidemic or pandemic influenza. Here, we discuss current vaccines to protect humans and animals against influenza, highlighting challenges faced to effective and uniform novel vaccination strategies and approaches. PMID:29467737

Can transcranial electrical stimulation improve learning difficulties in atypical brain development? A future possibility for cognitive training☆

PubMed Central

Krause, Beatrix; Cohen Kadosh, Roi

2013-01-01

Learning difficulties in atypical brain development represent serious obstacles to an individual's future achievements and can have broad societal consequences. Cognitive training can improve learning impairments only to a certain degree. Recent evidence from normal and clinical adult populations suggests that transcranial electrical stimulation (TES), a portable, painless, inexpensive, and relatively safe neuroenhancement tool, applied in conjunction with cognitive training can enhance cognitive intervention outcomes. This includes, for instance, numerical processing, language skills and response inhibition deficits commonly associated with profound learning difficulties and attention-deficit hyperactivity disorder (ADHD). The current review introduces the functional principles, current applications and promising results, and potential pitfalls of TES. Unfortunately, research in child populations is limited at present. We suggest that TES has considerable promise as a tool for increasing neuroplasticity in atypically developing children and may be an effective adjunct to cognitive training in clinical settings if it proves safe. The efficacy and both short- and long-term effects of TES on the developing brain need to be critically assessed before it can be recommended for clinical settings. PMID:23770059

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.

Safety and efficacy of vagus nerve stimulation paired with tones for the treatment of tinnitus: a case series.

PubMed

De Ridder, Dirk; Vanneste, Sven; Engineer, Navzer D; Kilgard, Michael P

2014-02-01

Classical neuromodulation applies current to the nervous system in an attempt to alter ongoing activity. However, classical neuromodulation interferes with activity but does not drive it in a controlled way. Recently, an animal study demonstrated it is possible to drive plasticity in a controlled way by using stimulation of the vagus nerve paired with tones. This reversed the tinnitus percept and pathological neural plasticity in noise-exposed rats with behavioral characteristics of tinnitus. The aim of the current study was to translate this innovative neuromodulation method to humans suffering from tinnitus. Ten patients with severe chronic tinnitus were implanted with electrodes on their left vagus nerve. Two and a half hours each day for 20 days, the patients heard tones, excluding the tinnitus-matched frequency, paired with brief electrical stimulation of the vagus nerve. The therapy was well tolerated, and no patient withdrew from the study due to complications or side-effects. Four of the ten patients exhibited clinically meaningful improvements in their tinnitus, both for the affective component, as quantified by the Tinnitus Handicap Inventory, and for the sound percept, as quantified by the minimum masking level. These improvements were stable for more than two months after the end of therapy. Of the ten patients, five were on medications that included muscarinic antagonists, norepinephrine agonists, and γ-amino butyric acid agonists, thereby possibly interfering with acetylcholine and norepinephrine release induced by vagus nerve stimulation (VNS) and essential for inducing plasticity. These patients had no improvement in contrast to medication-free patients. VNS paired with tones excluding the tinnitus-matched frequency is safe and feasible. It seems to exert a beneficial effect in nonmedication-taking patients, both with regard to the perceived sound and the distress. Further studies are therefore mandated. © 2013 International Neuromodulation Society.

Non-invasive Brain Stimulation: Probing Intracortical Circuits and Improving Cognition in the Aging Brain

PubMed Central

Gomes-Osman, Joyce; Indahlastari, Aprinda; Fried, Peter J.; Cabral, Danylo L. F.; Rice, Jordyn; Nissim, Nicole R.; Aksu, Serkan; McLaren, Molly E.; Woods, Adam J.

2018-01-01

The impact of cognitive aging on brain function and structure is complex, and the relationship between aging-related structural changes and cognitive function are not fully understood. Physiological and pathological changes to the aging brain are highly variable, making it difficult to estimate a cognitive trajectory with which to monitor the conversion to cognitive decline. Beyond the information on the structural and functional consequences of cognitive aging gained from brain imaging and neuropsychological studies, non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) can enable stimulation of the human brain in vivo, offering useful insights into the functional integrity of intracortical circuits using electrophysiology and neuromodulation. TMS measurements can be used to identify and monitor changes in cortical reactivity, the integrity of inhibitory and excitatory intracortical circuits, the mechanisms of long-term potentiation (LTP)/depression-like plasticity and central cholinergic function. Repetitive TMS and tDCS can be used to modulate neuronal excitability and enhance cortical function, and thus offer a potential means to slow or reverse cognitive decline. This review will summarize and critically appraise relevant literature regarding the use of TMS and tDCS to probe cortical areas affected by the aging brain, and as potential therapeutic tools to improve cognitive function in the aging population. Challenges arising from intra-individual differences, limited reproducibility, and methodological differences will be discussed.

Stimulus Characteristics for Vestibular Stochastic Resonance to Improve Balance Function

NASA Technical Reports Server (NTRS)

Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Peters, Brian; Wood, Scott; Serrado, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob

2010-01-01

Stochastic resonance (SR) is a mechanism by which noise can enhance the response of neural systems to relevant sensory signals. Studies have shown that imperceptible stochastic vestibular electrical stimulation, when applied to normal young and elderly subjects, significantly improved their ocular stabilization reflexes in response to whole-body tilt as well as balance performance during postural disturbances. The goal of this study was to optimize the amplitude characteristics of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standard balance task of standing on a block of foam with their eyes closed. Bipolar stochastic electrical stimulation was applied to the vestibular system using constant current stimulation through electrodes placed over the mastoid process behind the ears. Amplitude of the signals varied in the range of 0-700 microamperes. Balance performance was measured using a force plate under the foam block, and inertial motion sensors were placed on the torso and head. Balance performance with stimulation was significantly greater (10%-25%) than with no stimulation. The signal amplitude at which performance was maximized was in the range of 100-300 microamperes. Optimization of the amplitude of the stochastic signals for maximizing balance performance will have a significant impact on development of vestibular SR as a unique system to aid recovery of function in astronauts after long-duration space flight or in patients with balance disorders.

Task-dependent and distinct roles of the temporoparietal junction and inferior frontal cortex in the control of imitation.

PubMed

Hogeveen, Jeremy; Obhi, Sukhvinder S; Banissy, Michael J; Santiesteban, Idalmis; Press, Clare; Catmur, Caroline; Bird, Geoffrey

2015-07-01

The control of neurological networks supporting social cognition is crucially important for social interaction. In particular, the control of imitation is directly linked to interaction quality, with impairments associated with disorders characterized by social difficulties. Previous work suggests inferior frontal cortex (IFC) and the temporoparietal junction (TPJ) are involved in controlling imitation, but the functional roles of these areas remain unclear. Here, transcranial direct current stimulation (tDCS) was used to enhance cortical excitability at IFC and the TPJ prior to the completion of three tasks: (i) a naturalistic social interaction during which increased imitation is known to improve rapport, (ii) a choice reaction time task in which imitation needs to be inhibited for successful performance and (iii) a non-imitative control task. Relative to sham stimulation, stimulating IFC improved the context-dependent control of imitation-participants imitated more during the social interaction and less during the imitation inhibition task. In contrast, stimulating the TPJ reduced imitation in the inhibition task without affecting imitation during social interaction. Neither stimulation site affected the non-imitative control task. These data support a model in which IFC modulates imitation directly according to task demands, whereas TPJ controls task-appropriate shifts in attention toward representation of the self or the other, indirectly impacting upon imitation. © The Author (2014). Published by Oxford University Press.

Towards a Switched-Capacitor Based Stimulator for Efficient Deep-Brain Stimulation

PubMed Central

Vidal, Jose; Ghovanloo, Maysam

2013-01-01

We have developed a novel 4-channel prototype stimulation circuit for implantable neurological stimulators (INS). This Switched-Capacitor based Stimulator (SCS) aims to utilize charge storage and charge injection techniques to take advantage of both the efficiency of conventional voltage-controlled stimulators (VCS) and the safety and controllability of current-controlled stimulators (CCS). The discrete SCS prototype offers fine control over stimulation parameters such as voltage, current, pulse width, frequency, and active electrode channel via a LabVIEW graphical user interface (GUI) when connected to a PC through USB. Furthermore, the prototype utilizes a floating current sensor to provide charge-balanced biphasic stimulation and ensure safety. The stimulator was analyzed using an electrode-electrolyte interface (EEI) model as well as with a pair of pacing electrodes in saline. The primary motivation of this research is to test the feasibility and functionality of a safe, effective, and power-efficient switched-capacitor based stimulator for use in Deep Brain Stimulation. PMID:21095987

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.

New Treatment Strategies of Depression: Based on Mechanisms Related to Neuroplasticity

PubMed Central

Lane, Hsien-Yuan

2017-01-01

Major depressive disorder is a severe and complex mental disorder. Impaired neurotransmission and disrupted signalling pathways may influence neuroplasticity, which is involved in the brain dysfunction in depression. Traditional neurobiological theories of depression, such as monoamine hypothesis, cannot fully explain the whole picture of depressive disorders. In this review, we discussed new treatment directions of depression, including modulation of glutamatergic system and noninvasive brain stimulation. Dysfunction of glutamatergic neurotransmission plays an important role in the pathophysiology of depression. Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has rapid and lasting antidepressive effects in previous studies. In addition to ketamine, other glutamatergic modulators, such as sarcosine, also show potential antidepressant effect in animal models or clinical trials. Noninvasive brain stimulation is another new treatment strategy beyond pharmacotherapy. Growing evidence has demonstrated that superficial brain stimulations, such as transcranial magnetic stimulation, transcranial direct current stimulation, cranial electrotherapy stimulation, and magnetic seizure therapy, can improve depressive symptoms. The antidepressive effect of these brain stimulations may be through modulating neuroplasticity. In conclusion, drugs that modulate neurotransmission via NMDA receptor and noninvasive brain stimulation may provide new directions of treatment for depression. Furthermore, exploring the underlying mechanisms will help in developing novel therapies for depression in the future. PMID:28491480

Development of network-based multichannel neuromuscular electrical stimulation system for stroke rehabilitation.

PubMed

Qu, Hongen; Xie, Yongji; Liu, Xiaoxuan; He, Xin; Hao, Manzhao; Bao, Yong; Xie, Qing; Lan, Ning

2016-01-01

Neuromuscular electrical stimulation (NMES) is a promising assistive technology for stroke rehabilitation. Here we present the design and development of a multimuscle stimulation system as an emerging therapy for people with paretic stroke. A network-based multichannel NMES system was integrated based on dual bus architecture of communication and an H-bridge current regulator with a power booster. The structure of the system was a body area network embedded with multiple stimulators and a communication protocol of controlled area network to transmit muscle stimulation parameter information to individual stimulators. A graphical user interface was designed to allow clinicians to specify temporal patterns and muscle stimulation parameters. We completed and tested a prototype of the hardware and communication software modules of the multichannel NMES system. The prototype system was first verified in nondisabled subjects for safety, and then tested in subjects with stroke for feasibility with assisting multijoint movements. Results showed that synergistic stimulation of multiple muscles in subjects with stroke improved performance of multijoint movements with more natural velocity profiles at elbow and shoulder and reduced acromion excursion due to compensatory trunk rotation. The network-based NMES system may provide an innovative solution that allows more physiological activation of multiple muscles in multijoint task training for patients with stroke.

Augmented cartilage regeneration by implantation of cellular versus acellular implants after bone marrow stimulation: a systematic review and meta-analysis of animal studies.

PubMed

Pot, Michiel W; van Kuppevelt, Toin H; Gonzales, Veronica K; Buma, Pieter; IntHout, Joanna; de Vries, Rob B M; Daamen, Willeke F

2017-01-01

Bone marrow stimulation may be applied to regenerate focal cartilage defects, but generally results in transient clinical improvement and formation of fibrocartilage rather than hyaline cartilage. Tissue engineering and regenerative medicine strive to develop new solutions to regenerate hyaline cartilage tissue. This systematic review and meta-analysis provides a comprehensive overview of current literature and assesses the efficacy of articular cartilage regeneration by implantation of cell-laden versus cell-free biomaterials in the knee and ankle joint in animals after bone marrow stimulation. PubMed and EMBASE (via OvidSP) were systematically searched using tissue engineering, cartilage and animals search strategies. Included were primary studies in which cellular and acellular biomaterials were implanted after applying bone marrow stimulation in the knee or ankle joint in healthy animals. Study characteristics were tabulated and outcome data were collected for meta-analysis for studies applying semi-quantitative histology as outcome measure (117 studies). Cartilage regeneration was expressed on an absolute 0-100% scale and random effects meta-analyses were performed. Implantation of cellular biomaterials significantly improved cartilage regeneration by 18.6% compared to acellular biomaterials. No significant differences were found between biomaterials loaded with stem cells and those loaded with somatic cells. Culture conditions of cells did not affect cartilage regeneration. Cartilage formation was reduced with adipose-derived stem cells compared to other cell types, but still improved compared to acellular scaffolds. Assessment of the risk of bias was impaired due to incomplete reporting for most studies. Implantation of cellular biomaterials improves cartilage regeneration compared to acellular biomaterials.

Electrical engram: how deep brain stimulation affects memory.

PubMed

Lee, Hweeling; Fell, Jürgen; Axmacher, Nikolai

2013-11-01

Deep brain stimulation (DBS) is a surgical procedure involving implantation of a pacemaker that sends electric impulses to specific brain regions. DBS has been applied in patients with Parkinson's disease, depression, and obsessive-compulsive disorder (among others), and more recently in patients with Alzheimer's disease to improve memory functions. Current DBS approaches are based on the concept that high-frequency stimulation inhibits or excites specific brain regions. However, because DBS entails the application of repetitive electrical stimuli, it primarily exerts an effect on extracellular field-potential oscillations similar to those recorded with electroencephalography. Here, we suggest a new perspective on how DBS may ameliorate memory dysfunction: it may enhance normal electrophysiological patterns underlying long-term memory processes within the medial temporal lobe. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of anodal transcranial direct current stimulation (tDCS) on behavioral and spatial memory during the early stage of traumatic brain injury in the rats.

PubMed

Yoon, Kyung Jae; Lee, Yong-Taek; Chae, Seoung Wan; Park, Chae Ri; Kim, Dae Yul

2016-03-15

Transcranial direct current stimulation (tDCS) is a noninvasive technique to modulate the neural membrane potential. Its effects in the early stage of traumatic brain injury (TBI) have rarely been investigated. This study assessed the effects of anodal tDCS on behavioral and spatial memory in a rat model of traumatic brain injury. Thirty six rats underwent lateral fluid percussion and were then randomly assigned to one of three groups: control (n=12), five-day tDCS over peri-lesional cortex at one (1W, n=12), or two (2W, n=12) weeks post-injury. The Barnes maze (BM) and Rotarod (RR) tests were evaluated in a blind manner on day 1, week 3 and week 5 post-injury. After three weeks, both the 1W and 2W groups showed significant improvements in the BM ratio (P<0.05), whereas only group 2W obtained a significant improvement in the RR ratio compared with the control group (P<0.05). However, there were no significant differences between any of the groups at five weeks after TBI. Immunohistochemistry revealed that only group 2W had a significantly higher brain-derived neurotrophic factor (BDNF) expression in the peri-lesional cortex, which was significantly correlated with the improvement of the Rotarod test at 3-week post-injury. However, BDNF expression in the ipsi-lesional hippocampus was not significantly different among the three groups. Group 1W tended to have increased choline/creatine ratios, as measured by magnetic resonance spectroscopy in the peri-lesional cortex, than the control group (P=0.051). Neither regimen aggravated the lesion volume or brain edema measured by MRI. These beneficial effects were not observed with either regimen at five weeks post-injury. In conclusions, anodal tDCS ameliorated behavioral and spatial memory function in the early phase after TBI when it is delivered two weeks post-injury. Earlier stimulation (one week post-injury) improves spatial memory only. However, the beneficial effects did not persist after cessation of the anodal stimulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of a cochlear-implant processing strategy incorporating phantom stimulation and asymmetric pulses.

PubMed

Carlyon, Robert P; Monstrey, Jolijn; Deeks, John M; Macherey, Olivier

2014-12-01

To evaluate a speech-processing strategy in which the lowest frequency channel is conveyed using an asymmetric pulse shape and "phantom stimulation", where current is injected into one intra-cochlear electrode and where the return current is shared between an intra-cochlear and an extra-cochlear electrode. This strategy is expected to provide more selective excitation of the cochlear apex, compared to a standard strategy where the lowest-frequency channel is conveyed by symmetric pulses in monopolar mode. In both strategies all other channels were conveyed by monopolar stimulation. Within-subjects comparison between the two strategies. Four experiments: (1) discrimination between the strategies, controlling for loudness differences, (2) consonant identification, (3) recognition of lowpass-filtered sentences in quiet, (4) sentence recognition in the presence of a competing speaker. Eight users of the Advanced Bionics CII/Hi-Res 90k cochlear implant. Listeners could easily discriminate between the two strategies but no consistent differences in performance were observed. The proposed method does not improve speech perception, at least in the short term.

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

Transcranial direct current stimulation (tDCS) facilitates overall visual search response times but does not interact with visual search task factors

PubMed Central

Gordon, Barry

2018-01-01

Whether transcranial direct current stimulation (tDCS) affects mental functions, and how any such effects arise from its neural effects, continue to be debated. We investigated whether tDCS applied over the visual cortex (Oz) with a vertex (Cz) reference might affect response times (RTs) in a visual search task. We also examined whether any significant tDCS effects would interact with task factors (target presence, discrimination difficulty, and stimulus brightness) that are known to selectively influence one or the other of the two information processing stages posited by current models of visual search. Based on additive factor logic, we expected that the pattern of interactions involving a significant tDCS effect could help us colocalize the tDCS effect to one (or both) of the processing stages. In Experiment 1 (n = 12), anodal tDCS improved RTs significantly; cathodal tDCS produced a nonsignificant trend toward improvement. However, there were no interactions between the anodal tDCS effect and target presence or discrimination difficulty. In Experiment 2 (n = 18), we manipulated stimulus brightness along with target presence and discrimination difficulty. Anodal and cathodal tDCS both produced significant improvements in RTs. Again, the tDCS effects did not interact with any of the task factors. In Experiment 3 (n = 16), electrodes were placed at Cz and on the upper arm, to test for a possible effect of incidental stimulation of the motor regions under Cz. No effect of tDCS on RTs was found. These findings strengthen the case for tDCS having real effects on cerebral information processing. However, these effects did not clearly arise from either of the two processing stages of the visual search process. We suggest that this is because tDCS has a DIFFUSE, pervasive action across the task-relevant neuroanatomical region(s), not a discrete effect in terms of information processing stages. PMID:29558513

Transcranial direct current stimulation (tDCS) facilitates overall visual search response times but does not interact with visual search task factors.

PubMed

Sung, Kyongje; Gordon, Barry

2018-01-01

Whether transcranial direct current stimulation (tDCS) affects mental functions, and how any such effects arise from its neural effects, continue to be debated. We investigated whether tDCS applied over the visual cortex (Oz) with a vertex (Cz) reference might affect response times (RTs) in a visual search task. We also examined whether any significant tDCS effects would interact with task factors (target presence, discrimination difficulty, and stimulus brightness) that are known to selectively influence one or the other of the two information processing stages posited by current models of visual search. Based on additive factor logic, we expected that the pattern of interactions involving a significant tDCS effect could help us colocalize the tDCS effect to one (or both) of the processing stages. In Experiment 1 (n = 12), anodal tDCS improved RTs significantly; cathodal tDCS produced a nonsignificant trend toward improvement. However, there were no interactions between the anodal tDCS effect and target presence or discrimination difficulty. In Experiment 2 (n = 18), we manipulated stimulus brightness along with target presence and discrimination difficulty. Anodal and cathodal tDCS both produced significant improvements in RTs. Again, the tDCS effects did not interact with any of the task factors. In Experiment 3 (n = 16), electrodes were placed at Cz and on the upper arm, to test for a possible effect of incidental stimulation of the motor regions under Cz. No effect of tDCS on RTs was found. These findings strengthen the case for tDCS having real effects on cerebral information processing. However, these effects did not clearly arise from either of the two processing stages of the visual search process. We suggest that this is because tDCS has a DIFFUSE, pervasive action across the task-relevant neuroanatomical region(s), not a discrete effect in terms of information processing stages.

Optimal number of stimulation contacts for coordinated reset neuromodulation

PubMed Central

Lysyansky, Borys; Popovych, Oleksandr V.; Tass, Peter A.

2013-01-01

In this computational study we investigate coordinated reset (CR) neuromodulation designed for an effective control of synchronization by multi-site stimulation of neuronal target populations. This method was suggested to effectively counteract pathological neuronal synchrony characteristic for several neurological disorders. We study how many stimulation sites are required for optimal CR-induced desynchronization. We found that a moderate increase of the number of stimulation sites may significantly prolong the post-stimulation desynchronized transient after the stimulation is completely switched off. This can, in turn, reduce the amount of the administered stimulation current for the intermittent ON–OFF CR stimulation protocol, where time intervals with stimulation ON are recurrently followed by time intervals with stimulation OFF. In addition, we found that the optimal number of stimulation sites essentially depends on how strongly the administered current decays within the neuronal tissue with increasing distance from the stimulation site. In particular, for a broad spatial stimulation profile, i.e., for a weak spatial decay rate of the stimulation current, CR stimulation can optimally be delivered via a small number of stimulation sites. Our findings may contribute to an optimization of therapeutic applications of CR neuromodulation. PMID:23885239

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.

Modeling Intracochlear Magnetic Stimulation: A Finite-Element Analysis.

PubMed

Mukesh, S; Blake, D T; McKinnon, B J; Bhatti, P T

2017-08-01

This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (~100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.

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

Is Transcranial Direct Current Stimulation an Effective Predictor for Invasive Occipital Nerve Stimulation Treatment Success in Fibromyalgia Patients?

PubMed

Plazier, Mark; Tchen, Stephanie; Ost, Jan; Joos, Kathleen; De Ridder, Dirk; Vanneste, Sven

2015-10-01

Fibromyalgia is a disorder distinguished by pervasive musculoskeletal pain that has pervasive effects on affected individuals magnifying the importance of finding a safe and viable treatment option. The goal of this study is to investigate if transcranial direct current stimulation (tDCS) treatment can predict the outcome of occipital nerve field stimulation (ONFS) via a subcutaneous electrode. Nine patients with fibromyalgia were selected fulfilling the American College of Rheumatology-90 criteria. The patients were implanted with a subcutaneous trial-lead in the C2 dermatome innervated by the occipital nerve. After the treatment phase of ONFS using a C2 implant, each patient participated in three sessions of tDCS. Stimulation outcomes for pain suppression were examined between the two methods to determine possible correlations. Positive correlation of stimulation effect was noted between the numeric rating scale changes for pain obtained by tDCS treatments and short-term measures of ONFS, but no correlation was noted between tDCS and long-term ONFS outcomes. A correlation also was noted between short-term ONS C2 implant pain suppression and long-term ONS C2 implant treatment success. This pilot study suggests that tDCS is a predictive measure for success of OFNS in short-term but cannot be used as a predictive measure for success of long-term OFNS. Our data confirm previous findings that ONFS via an implanted electrode can improve fibromyalgia pain in a placebo-controlled way and exert a long-term pain suppression effect for ONFS via an implanted electrode. © 2015 International Neuromodulation Society.

Improved convection compensating pulsed field gradient spin-echo and stimulated-echo methods.

PubMed

Sørland, G H; Seland, J G; Krane, J; Anthonsen, H W

2000-02-01

The need for convection compensating methods in NMR has been manifested through an increasing number of publications related to the subject over the past few years (J. Magn. Reson. 125, 372 (1997); 132, 13 (1998); 131, 126 (1998); 118, 50 (1996); 133, 379 (1998)). When performing measurements at elevated temperature, small convection currents may give rise to erroneous values of the diffusion coefficient. In work with high resolution NMR spectroscopy, the application of magnetic field gradients also introduces an eddy-current magnetic field which may result in errors in phase and baseline in the FFT-spectra. The eddy current field has been greatly suppressed by the application of bipolar magnetic field gradients. However, when introducing bipolar magnetic field gradients, the pulse sequence is lengthened significantly. This has recently been pointed out as a major drawback because of the loss of coherence and of NMR-signal due to transverse relaxation processes. Here we present modified convection compensating pulsed field gradient double spin echo and double stimulated echo sequences which suppress the eddy-current magnetic field without increasing the duration of the pulse sequences. Copyright 2000 Academic Press.

An Incubatable Direct Current Stimulation System for In Vitro Studies of Mammalian Cells

PubMed Central

Panitch, Alyssa; Caplan, Michael; Sweeney, James D.

2012-01-01

Abstract The purpose of this study was to provide a simplified alternative technology and format for direct current stimulation of mammalian cells. An incubatable reusable stimulator was developed that effectively delivers a regulated current and does not require constant monitoring. PMID:23514694

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.

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.

The effect of transcutaneous electrical nerve stimulation in patients with acute exacerbation of chronic obstructive pulmonary disease: randomised controlled trial.

PubMed

Öncü, Emine; Zincir, Handan

2017-07-01

The aim of the present study was to assess the efficacy of transcutaneous electrical nerve stimulation in patients with acute exacerbation of chronic obstructive pulmonary disease. In patients with stable chronic obstructive pulmonary disease, transcutaneous electrical nerve stimulation has been known to attain improvement in forced expiratory volume in 1 seconds, physical activity, and quality of life. However, information about the effects of transcutaneous electrical nerve stimulation on acute exacerbation of chronic obstructive pulmonary disease is quite limited. A single-blind, randomised controlled trial. Data were collected between August 2013-May 2014. Eighty-two patients who were hospitalised with a diagnosis of acute exacerbation of chronic obstructive pulmonary disease were randomly assigned to a transcutaneous electrical nerve stimulation group receiving transcutaneous electrical nerve stimulation treatment for 20 seance over the acupuncture points with pharmacotherapy or placebo group receiving the same treatment without electrical current output from the transcutaneous electrical nerve stimulation device. Pulmonary functional test, six-minute walking distance, dyspnoea and fatigue scale, and St. George's Respiratory Questionnaire scores were assessed pre- and postprogram. The program started at the hospital by the researcher was sustained in the patient's home by the caregiver. All patients were able to complete the program, despite the exacerbation. The 20 seance transcutaneous electrical nerve stimulation program provided clinically significant improvement in forced expiratory volume in 1 seconds 21 ml, 19·51% but when compared with the placebo group, the difference was insignificant (p > 0·05). The six-minute walking distance increased by 48·10 m more in the placebo group (p < 0·05). There were no significant differences between the two groups' St. George's Respiratory Questionnaire, dyspnoea and fatigue score (p > 0·05). Adding transcutaneous electrical nerve stimulation therapy to pharmacotherapy in patients with acute exacerbation of chronic obstructive pulmonary disease provided clinical improvement in forced expiratory volume in 1 seconds and add benefit in exercise capacity, but no significant effect on the other outcomes measured. Transcutaneous electrical nerve stimulation can be used as a non-invasive complementary therapy due to its beneficial effects on forced expiratory volume in 1 seconds and exercise capacity in patients with acute exacerbation of chronic obstructive pulmonary disease. © 2016 John Wiley & Sons Ltd.

Deep brain stimulation modulates synchrony within spatially and spectrally distinct resting state networks in Parkinson's disease.

PubMed

Oswal, Ashwini; Beudel, Martijn; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Litvak, Vladimir; Brown, Peter

2016-05-01

Chronic dopamine depletion in Parkinson's disease leads to progressive motor and cognitive impairment, which is associated with the emergence of characteristic patterns of synchronous oscillatory activity within cortico-basal-ganglia circuits. Deep brain stimulation of the subthalamic nucleus is an effective treatment for Parkinson's disease, but its influence on synchronous activity in cortico-basal-ganglia loops remains to be fully characterized. Here, we demonstrate that deep brain stimulation selectively suppresses certain spatially and spectrally segregated resting state subthalamic nucleus-cortical networks. To this end we used a validated and novel approach for performing simultaneous recordings of the subthalamic nucleus and cortex using magnetoencephalography (during concurrent subthalamic nucleus deep brain stimulation). Our results highlight that clinically effective subthalamic nucleus deep brain stimulation suppresses synchrony locally within the subthalamic nucleus in the low beta oscillatory range and furthermore that the degree of this suppression correlates with clinical motor improvement. Moreover, deep brain stimulation relatively selectively suppressed synchronization of activity between the subthalamic nucleus and mesial premotor regions, including the supplementary motor areas. These mesial premotor regions were predominantly coupled to the subthalamic nucleus in the high beta frequency range, but the degree of deep brain stimulation-associated suppression in their coupling to the subthalamic nucleus was not found to correlate with motor improvement. Beta band coupling between the subthalamic nucleus and lateral motor areas was not influenced by deep brain stimulation. Motor cortical coupling with subthalamic nucleus predominantly involved driving of the subthalamic nucleus, with those drives in the higher beta frequency band having much shorter net delays to subthalamic nucleus than those in the lower beta band. These observations raise the possibility that cortical connectivity with the subthalamic nucleus in the high and low beta bands may reflect coupling mediated predominantly by the hyperdirect and indirect pathways to subthalamic nucleus, respectively, and that subthalamic nucleus deep brain stimulation predominantly suppresses the former. Yet only the change in strength of local subthalamic nucleus oscillations correlates with the degree of improvement during deep brain stimulation, compatible with the current view that a strengthened hyperdirect pathway is a prerequisite for locally generated beta activity but that it is the severity of the latter that may determine or index motor impairment. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.

Deep brain stimulation modulates synchrony within spatially and spectrally distinct resting state networks in Parkinson’s disease

PubMed Central

Oswal, Ashwini; Beudel, Martijn; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Litvak, Vladimir

2016-01-01

Abstract Chronic dopamine depletion in Parkinson’s disease leads to progressive motor and cognitive impairment, which is associated with the emergence of characteristic patterns of synchronous oscillatory activity within cortico-basal-ganglia circuits. Deep brain stimulation of the subthalamic nucleus is an effective treatment for Parkinson’s disease, but its influence on synchronous activity in cortico-basal-ganglia loops remains to be fully characterized. Here, we demonstrate that deep brain stimulation selectively suppresses certain spatially and spectrally segregated resting state subthalamic nucleus–cortical networks. To this end we used a validated and novel approach for performing simultaneous recordings of the subthalamic nucleus and cortex using magnetoencephalography (during concurrent subthalamic nucleus deep brain stimulation). Our results highlight that clinically effective subthalamic nucleus deep brain stimulation suppresses synchrony locally within the subthalamic nucleus in the low beta oscillatory range and furthermore that the degree of this suppression correlates with clinical motor improvement. Moreover, deep brain stimulation relatively selectively suppressed synchronization of activity between the subthalamic nucleus and mesial premotor regions, including the supplementary motor areas. These mesial premotor regions were predominantly coupled to the subthalamic nucleus in the high beta frequency range, but the degree of deep brain stimulation-associated suppression in their coupling to the subthalamic nucleus was not found to correlate with motor improvement. Beta band coupling between the subthalamic nucleus and lateral motor areas was not influenced by deep brain stimulation. Motor cortical coupling with subthalamic nucleus predominantly involved driving of the subthalamic nucleus, with those drives in the higher beta frequency band having much shorter net delays to subthalamic nucleus than those in the lower beta band. These observations raise the possibility that cortical connectivity with the subthalamic nucleus in the high and low beta bands may reflect coupling mediated predominantly by the hyperdirect and indirect pathways to subthalamic nucleus, respectively, and that subthalamic nucleus deep brain stimulation predominantly suppresses the former. Yet only the change in strength of local subthalamic nucleus oscillations correlates with the degree of improvement during deep brain stimulation, compatible with the current view that a strengthened hyperdirect pathway is a prerequisite for locally generated beta activity but that it is the severity of the latter that may determine or index motor impairment. PMID:27017189

Transcranial direct current stimulation (tDCS) of frontal cortex decreases performance on the WAIS-IV intelligence test.

PubMed

Sellers, Kristin K; Mellin, Juliann M; Lustenberger, Caroline M; Boyle, Michael R; Lee, Won Hee; Peterchev, Angel V; Fröhlich, Flavio

2015-09-01

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 were included in the final analysis. These 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, 2 mA at each anode for 20 min) or active sham tDCS (2 mA for 40 s), and participants in substudy 2 received either right or left tDCS (anode over either F4 or F3, cathode over Cz, 2 mA for 20 min). 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. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrical stimulation (ES) in the management of sexual pain disorders.

PubMed

Nappi, Rossella E; Ferdeghini, Francesea; Abbiati, Ileana; Vercesi, Claudia; Farina, Claudio; Polatti, Franco

2003-01-01

We performed an open study to investigate the use of electrical stimulation (ES) on the vestibular area and vaginal introitus in women with sexual pain disorders. We recruited 29 women (age range 20-45 years) from among the patients at our Reproductive Psychobiology Unit to participate in the present study. They each experienced vestibular pain, inducing dyspareunia and vaginism. We performed ES with an ECL43400 apparatus (Elite, EssediEsse srl, Milan, Italy) once a week for 10 weeks. To evaluate the muscular activity of the perineal floor and sexual function, we employed the same apparatus with a vaginal probe for recording myoelectrical activity (muV), we employed a VAS scale for evaluating pain, and we administered the Female Sexual Function Index (FSFI; Rosen et al., 2000) before and after the study protocol. We analyzed data by parametric and nonparametric comparisons and correlations, as appropriate. Our major findings were as follows: (a) the contractile ability of pelvic floor muscles (p < 0.001), as well as the resting ability (p < 0.001), significantly improved following ES; (b) the current intensity tolerated significantly increased (p < 0.001) throughout the study, from 41.3 +/- 7.4 mA at the start of the study to 50 +/- 7.4 mA at the end of the stimulation protocol; (c) the Visual Analogic Scale (VAS) for pain significantly declined (p < 0.001), whereas FSFI pain scores (p < 0.001) and full scale scores (p < 0.001) significantly improved following ES, and 4 out of 9 women with vaginism went back to coital activity; (d) FSFI pain score and the current intensity tolerated, both before (R = .59; p < 0.006) and at the end (R = .53; p < 0.02) of the stimulation protocol, positively correlated. ES may be effective in the management of sexual pain disorders. Further controlled studies are necessary to standardize stimulation protocols according to the severity of pain and to better clarify the long-term clinical effects of ES.

Individual differences in learning correlate with modulation of brain activity induced by transcranial direct current stimulation

PubMed Central

Falcone, Brian; Wada, Atsushi; Parasuraman, Raja

2018-01-01

Transcranial direct current stimulation (tDCS) has been shown to enhance cognitive performance on a variety of tasks. It is hypothesized that tDCS enhances performance by affecting task related cortical excitability changes in networks underlying or connected to the site of stimulation facilitating long term potentiation. However, many recent studies have called into question the reliability and efficacy of tDCS to induce modulatory changes in brain activity. In this study, our goal is to investigate the individual differences in tDCS induced modulatory effects on brain activity related to the degree of enhancement in performance, providing insight into this lack of reliability. In accomplishing this goal, we used functional magnetic resonance imaging (fMRI) concurrently with tDCS stimulation (1 mA, 30 minutes duration) using a visual search task simulating real world conditions. The experiment consisted of three fMRI sessions: pre-training (no performance feedback), training (performance feedback which included response accuracy and target location and either real tDCS or sham stimulation given), and post-training (no performance feedback). The right posterior parietal cortex was selected as the site of anodal tDCS based on its known role in visual search and spatial attention processing. Our results identified a region in the right precentral gyrus, known to be involved with visual spatial attention and orienting, that showed tDCS induced task related changes in cortical excitability that were associated with individual differences in improved performance. This same region showed greater activity during the training session for target feedback of incorrect (target-error feedback) over correct trials for the tDCS stim over sham group indicating greater attention to target features during training feedback when trials were incorrect. These results give important insight into the nature of neural excitability induced by tDCS as it relates to variability in individual differences in improved performance shedding some light the apparent lack of reliability found in tDCS research. PMID:29782510

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.

A trial of scheduled deep brain stimulation for Tourette syndrome: moving away from continuous deep brain stimulation paradigms.

PubMed

Okun, Michael S; Foote, Kelly D; Wu, Samuel S; Ward, Herbert E; Bowers, Dawn; Rodriguez, Ramon L; Malaty, Irene A; Goodman, Wayne K; Gilbert, Donald M; Walker, Harrison C; Mink, Jonathan W; Merritt, Stacy; Morishita, Takashi; Sanchez, Justin C

2013-01-01

To collect the information necessary to design the methods and outcome variables for a larger trial of scheduled deep brain stimulation (DBS) for Tourette syndrome. We performed a small National Institutes of Health-sponsored clinical trials planning study of the safety and preliminary efficacy of implanted DBS in the bilateral centromedian thalamic region. The study used a cranially contained constant-current device and a scheduled, rather than the classic continuous, DBS paradigm. Baseline vs 6-month outcomes were collected and analyzed. In addition, we compared acute scheduled vs acute continuous vs off DBS. A university movement disorders center. Five patients with implanted DBS. A 50% improvement in the Yale Global Tic Severity Scale (YGTSS) total score. RESULTS Participating subjects had a mean age of 34.4 (range, 28-39) years and a mean disease duration of 28.8 years. No significant adverse events or hardware-related issues occurred. Baseline vs 6-month data revealed that reductions in the YGTSS total score did not achieve the prestudy criterion of a 50% improvement in the YGTSS total score on scheduled stimulation settings. However, statistically significant improvements were observed in the YGTSS total score (mean [SD] change, -17.8 [9.4]; P=.01), impairment score (-11.3 [5.0]; P=.007), and motor score (-2.8 [2.2]; P=.045); the Modified Rush Tic Rating Scale Score total score (-5.8 [2.9]; P=.01); and the phonic tic severity score (-2.2 [2.6]; P=.04). Continuous, off, and scheduled stimulation conditions were assessed blindly in an acute experiment at 6 months after implantation. The scores in all 3 conditions showed a trend for improvement. Trends for improvement also occurred with continuous and scheduled conditions performing better than the off condition. Tic suppression was commonly seen at ventral (deep) contacts, and programming settings resulting in tic suppression were commonly associated with a subjective feeling of calmness. This study provides safety and proof of concept that a scheduled DBS approach could improve motor and vocal tics in Tourette syndrome. Refinements in neurostimulator battery life, outcome measure selection, and flexibility in programming settings can be used to enhance outcomes in a future larger study. Scheduled stimulation holds promise as a potential first step for shifting movement and neuropsychiatric disorders toward more responsive neuromodulation approaches. clinicaltrials.gov Identifier: NCT01329198.

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.

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.

Effects of different electrical brain stimulation protocols on subcomponents of motor skill learning.

PubMed

Prichard, George; Weiller, Cornelius; Fritsch, Brita; Reis, Janine

2014-01-01

Noninvasive electrical brain stimulation (NEBS) with transcranial direct current (tDCS) or random noise stimulation (tRNS) applied to the primary motor cortex (M1) can augment motor learning. We tested whether different types of stimulation alter particular aspects of learning a tracing task over three consecutive days, namely skill acquisition (online/within session effects) or consolidation (offline/between session effects). Motor training on a tracing task over three consecutive days was combined with different types and montages of stimulation (tDCS, tRNS). Unilateral M1 stimulation using tRNS as well as unilateral and bilateral M1 tDCS all enhanced motor skill learning compared to sham stimulation. In all groups, this appeared to be driven by online effects without an additional offline effect. Unilateral tDCS resulted in large skill gains immediately following the onset of stimulation, while tRNS exerted more gradual effects. Control stimulation of the right temporal lobe did not enhance skill learning relative to sham. The mechanisms of action of tDCS and tRNS are likely different. Hence, the time course of skill improvement within sessions could point to specific and temporally distinct interactions with the physiological process of motor skill learning. Exploring the parameters of NEBS on different tasks and in patients with brain injury will allow us to maximize the benefits of NEBS for neurorehabilitation. Copyright © 2014 Elsevier Inc. All rights reserved.

Nickel-hydrogen bipolar battery system

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1982-01-01

Rechargeable nickel-hydrogen systems are described that more closely resemble a fuel cell system than a traditional nickel-cadmium battery pack. This was stimulated by the currently emerging requirements related to large manned and unmanned low Earth orbit applications. The resultant nickel-hydrogen battery system should have a number of features that would lead to improved reliability, reduced costs as well as superior energy density and cycle lives as compared to battery systems constructed from the current state-of-the-art nickel-hydrogen individual pressure vessel cells.

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.

Using the infrastructure of a conditional cash transfer program to deliver a scalable integrated early child development program in Colombia: cluster randomized controlled trial.

PubMed

Attanasio, Orazio P; Fernández, Camila; Fitzsimons, Emla O A; Grantham-McGregor, Sally M; Meghir, Costas; Rubio-Codina, Marta

2014-09-29

To assess the effectiveness of an integrated early child development intervention, combining stimulation and micronutrient supplementation and delivered on a large scale in Colombia, for children's development, growth, and hemoglobin levels. Cluster randomized controlled trial, using a 2 × 2 factorial design, with municipalities assigned to one of four groups: psychosocial stimulation, micronutrient supplementation, combined intervention, or control. 96 municipalities in Colombia, located across eight of its 32 departments. 1420 children aged 12-24 months and their primary carers. Psychosocial stimulation (weekly home visits with play demonstrations), micronutrient sprinkles given daily, and both combined. All delivered by female community leaders for 18 months. Cognitive, receptive and expressive language, and fine and gross motor scores on the Bayley scales of infant development-III; height, weight, and hemoglobin levels measured at the baseline and end of intervention. Stimulation improved cognitive scores (adjusted for age, sex, testers, and baseline levels of outcomes) by 0.26 of a standard deviation (P=0.002). Stimulation also increased receptive language by 0.22 of a standard deviation (P=0.032). Micronutrient supplementation had no significant effect on any outcome and there was no interaction between the interventions. No intervention affected height, weight, or hemoglobin levels. Using the infrastructure of a national welfare program we implemented the integrated early child development intervention on a large scale and showed its potential for improving children's cognitive development. We found no effect of supplementation on developmental or health outcomes. Moreover, supplementation did not interact with stimulation. The implementation model for delivering stimulation suggests that it may serve as a promising blueprint for future policy on early childhood development.Trial registration Current Controlled trials ISRCTN18991160. © Attanasio et al 2014.

Focalised stimulation using high definition transcranial direct current stimulation (HD-tDCS) to investigate declarative verbal learning and memory functioning.

PubMed

Nikolin, Stevan; Loo, Colleen K; Bai, Siwei; Dokos, Socrates; Martin, Donel M

2015-08-15

Declarative verbal learning and memory are known to be lateralised to the dominant hemisphere and to be subserved by a network of structures, including those located in frontal and temporal regions. These structures support critical components of verbal memory, including working memory, encoding, and retrieval. Their relative functional importance in facilitating declarative verbal learning and memory, however, remains unclear. To investigate the different functional roles of these structures in subserving declarative verbal learning and memory performance by applying a more focal form of transcranial direct current stimulation, "High Definition tDCS" (HD-tDCS). Additionally, we sought to examine HD-tDCS effects and electrical field intensity distributions using computer modelling. HD-tDCS was administered to the left dorsolateral prefrontal cortex (LDLPFC), planum temporale (PT), and left medial temporal lobe (LMTL) to stimulate the hippocampus, during learning on a declarative verbal memory task. Sixteen healthy participants completed a single blind, intra-individual cross-over, sham-controlled study which used a Latin Square experimental design. Cognitive effects on working memory and sustained attention were additionally examined. HD-tDCS to the LDLPFC significantly improved the rate of verbal learning (p=0.03, η(2)=0.29) and speed of responding during working memory performance (p=0.02, η(2)=0.35), but not accuracy (p=0.12, η(2)=0.16). No effect of tDCS on verbal learning, retention, or retrieval was found for stimulation targeted to the LMTL or the PT. Secondary analyses revealed that LMTL stimulation resulted in increased recency (p=0.02, η(2)=0.31) and reduced mid-list learning effects (p=0.01, η(2)=0.39), suggesting an inhibitory effect on learning. HD-tDCS to the LDLPFC facilitates the rate of verbal learning and improved efficiency of working memory may underlie performance effects. This focal method of administrating tDCS has potential for probing and enhancing cognitive functioning. Copyright © 2015 Elsevier Inc. All rights reserved.

Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling

PubMed Central

Luu, Phan; Essaki Arumugam, Easwara Moorthy; Anderson, Erik; Gunn, Amanda; Rech, Dennis; Turovets, Sergei; Tucker, Don M.

2016-01-01

In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual’s cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling. PMID:27531976

Improved selectivity from a wavelength addressable device for wireless stimulation of neural tissue

PubMed Central

Seymour, Elif Ç.; Freedman, David S.; Gökkavas, Mutlu; Özbay, Ekmel; Sahin, Mesut; Ünlü, M. Selim

2014-01-01

Electrical neural stimulation with micro electrodes is a promising technique for restoring lost functions in the central nervous system as a result of injury or disease. One of the problems related to current neural stimulators is the tissue response due to the connecting wires and the presence of a rigid electrode inside soft neural tissue. We have developed a novel, optically activated, microscale photovoltaic neurostimulator based on a custom layered compound semiconductor heterostructure that is both wireless and has a comparatively small volume (<0.01 mm3). Optical activation provides a wireless means of energy transfer to the neurostimulator, eliminating wires and the associated complications. This neurostimulator was shown to evoke action potentials and a functional motor response in the rat spinal cord. In this work, we extend our design to include wavelength selectivity and thus allowing independent activation of devices. As a proof of concept, we fabricated two different microscale devices with different spectral responsivities in the near-infrared region. We assessed the improved addressability of individual devices via wavelength selectivity as compared to spatial selectivity alone through on-bench optical measurements of the devices in combination with an in vivo light intensity profile in the rat cortex obtained in a previous study. We show that wavelength selectivity improves the individual addressability of the floating stimulators, thus increasing the number of devices that can be implanted in close proximity to each other. PMID:24600390

Impact of electro-stimulation on denitrifying bacterial growth and analysis of bacterial growth kinetics using a modified Gompertz model in a bio-electrochemical denitrification reactor.

PubMed

Liu, Hengyuan; Chen, Nan; Feng, Chuanping; Tong, Shuang; Li, Rui

2017-05-01

This study aimed to investigate the effect of electro-stimulation on denitrifying bacterial growth in a bio-electrochemical reactor, and the growth were modeled using modified Gompertz model under different current densities at three C/Ns. It was found that the similar optimum current density of 250mA/m 2 was obtained at C/N=0.75, 1.00 and 1.25, correspondingly the maximum nitrate removal efficiencies were 98.0%, 99.2% and 99.9%. Moreover, ATP content and cell membrane permeability of denitrifying bacteria were significantly increased at optimum current density. Furthermore, modified Gompertz model fitted well with the microbial growth curves, and the highest maximum growth rates (µ max ) and shorter lag time were obtained at the optimum current density for all C/Ns. This study demonstrated that the modified Gompertz model could be used for describing microbial growth under different current densities and C/Ns in a bio-electrochemical denitrification reactor, and it provided an alternative for improving the performance of denitrification process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Regenerative endodontics.

PubMed

Simon, S; Smith, A J

2014-03-01

Significant advances in our understanding of the biological processes involved in tooth development and repair at the cellular and molecular levels have underpinned the newly emerging area of regenerative endodontics. Development of treatment protocols based on exploiting the natural wound healing properties of the dental pulp and applying tissue engineering principles has allowed reporting of case series showing preservation of tissue vitality and apexogenesis. To review current case series reporting regenerative endodontics. Current treatment approaches tend to stimulate more reparative than regenerative responses in respect of the new tissue generated, which often does not closely resemble the physiological structure of dentine-pulp. However, despite these biological limitations, such techniques appear to offer significant promise for improved treatment outcomes. Improved biological outcomes will likely emerge from the many experimental studies being reported and will further contribute to improvements in clinical treatment protocols.

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.

Non-invasive brain stimulation in Parkinson's disease: Exploiting crossroads of cognition and mood.

PubMed

Dinkelbach, Lars; Brambilla, Michela; Manenti, Rosa; Brem, Anna-Katharine

2017-04-01

Cognitive impairments and depression are common non-motor manifestations in Parkinson's disease (PD). Recent evidence suggests that both partially arise via the same frontostriatal network, opening the opportunity for concomitant treatment with non-invasive brain stimulation (NIBS) techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). In this systematic review, we evaluate the effects of NIBS on cognition and/or mood in 19 placebo-controlled studies involving 561 PD patients. Outcomes depended on the area stimulated and the technique used. rTMS over the dorsolateral-prefrontal cortex (DLPFC) resulted in significant reductions in scores of depressive symptoms with moderate to large effect sizes along with increased performance in several tests of cognitive functions. tDCS over the DLPFC improved performance in several cognitive measures, including executive functions with large effect sizes. Additional effects of tDCS on mood were not detectable; however, only non-depressed patients were assessed. Further confirmatory research is needed to clarify the contribution that NIBS could make in the care of PD patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

The influence of functional electrical stimulation on hand motor recovery in stroke patients: a review.

PubMed

Quandt, Fanny; Hummel, Friedhelm C

2014-01-01

Neuromuscular stimulation has been used as one potential rehabilitative treatment option to restore motor function and improve recovery in patients with paresis. Especially stroke patients who often regain only limited hand function would greatly benefit from a therapy that enhances recovery and restores movement. Multiple studies investigated the effect of functional electrical stimulation on hand paresis, the results however are inconsistent. Here we review the current literature on functional electrical stimulation on hand motor recovery in stroke patients. We discuss the impact of different parameters such as stage after stoke, degree of impairment, spasticity and treatment protocols on the functional outcome. Importantly, we outline the results from recent studies investigating the cortical effects elicited by functional electrical stimulation giving insights into the underlying mechanisms responsible for long-term treatment effects. Bringing together the findings from present research it becomes clear that both, treatment outcomes as well as the neurophysiologic mechanisms causing functional recovery, vary depending on patient characteristics. In order to develop unified treatment guidelines it is essential to conduct homogenous studies assessing the impact of different parameters on rehabilitative success.

The influence of functional electrical stimulation on hand motor recovery in stroke patients: a review

PubMed Central

2014-01-01

Neuromuscular stimulation has been used as one potential rehabilitative treatment option to restore motor function and improve recovery in patients with paresis. Especially stroke patients who often regain only limited hand function would greatly benefit from a therapy that enhances recovery and restores movement. Multiple studies investigated the effect of functional electrical stimulation on hand paresis, the results however are inconsistent. Here we review the current literature on functional electrical stimulation on hand motor recovery in stroke patients. We discuss the impact of different parameters such as stage after stoke, degree of impairment, spasticity and treatment protocols on the functional outcome. Importantly, we outline the results from recent studies investigating the cortical effects elicited by functional electrical stimulation giving insights into the underlying mechanisms responsible for long-term treatment effects. Bringing together the findings from present research it becomes clear that both, treatment outcomes as well as the neurophysiologic mechanisms causing functional recovery, vary depending on patient characteristics. In order to develop unified treatment guidelines it is essential to conduct homogenous studies assessing the impact of different parameters on rehabilitative success. PMID:25276333

Nickel-hydrogen bipolar battery systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1982-01-01

Nickel-hydrogen cells are currently being manufactured on a semi-experimental basis. Rechargeable nickel-hydrogen systems are described that more closely resemble a fuel cell system than a traditional nickel-cadmium battery pack. This has been stimulated by the currently emerging requirements related to large manned and unmanned low earth orbit applications. The resultant nickel-hydrogen battery system should have a number of features that would lead to improved reliability, reduced costs as well as superior energy density and cycle lives as compared to battery systems constructed from the current state-of-the-art nickel-hydrogen individual pressure vessel cells.

Bioelectronic retinal prosthesis

NASA Astrophysics Data System (ADS)

Weiland, James D.

2016-05-01

Retinal prosthesis have been translated to clinical use over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa and one device is in clinical trials for treatment of age-related macular degeneration. These devices provide partial sight restoration and patients use this improved vision in their everyday lives to navigate and to detect large objects. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. In particular, current retinal prostheses do not provide peripheral visions due to technical and surgical limitations, thus limiting the effectiveness of the treatment. This paper reviews recent results from human implant patients and presents technical approaches for peripheral vision.

Transcranial direct current stimulation improves long-term memory deficits in an animal model of attention-deficit/hyperactivity disorder and modulates oxidative and inflammatory parameters.

PubMed

Leffa, Douglas Teixeira; Bellaver, Bruna; Salvi, Artur Alban; de Oliveira, Carla; Caumo, Wolnei; Grevet, Eugenio Horacio; Fregni, Felipe; Quincozes-Santos, André; Rohde, Luis Augusto; Torres, Iraci L S

2018-04-05

Transcranial direct current stimulation (tDCS) is a technique that modulates neuronal activity and has been proposed as a potential therapeutic tool for attention-deficit/hyperactivity disorder (ADHD) symptoms. Although pilot studies have shown evidence of efficacy, its mechanism of action remains unclear. We evaluated the effects of tDCS on behavioral (working and long-term memory) and neurochemical (oxidative and inflammatory parameters) outcomes related to ADHD pathophysiology. We used the most widely accepted animal model of ADHD: spontaneously hypertensive rats (SHR). The selected behavioral outcomes have been shown to be altered in both ADHD patients and animal models, and were chosen for their relation to the proposed mechanistic action of tDCS. Adult male SHR and their control, the Wistar Kyoto rats (WKY), were subjected to 20 min of bicephalic tDCS or sham stimulation for 8 consecutive days. Working memory, long-term memory, and neurochemical outcomes were evaluated. TDCS improved long-term memory deficits presented by the SHR. No change in working memory performance was observed. In the hippocampus, tDCS increased both the production of reactive oxygen species in SHR and the levels of the antioxidant molecule glutathione in both strains. TDCS also modulated inflammatory response in the brains of WKY by downregulating pro-inflammatory cytokines. TDCS had significant effects that were specific for strain, type of behavioral and neurochemical outcomes. The long-term memory improvement in the SHR may point to a possible therapeutic role of tDCS in ADHD that does not seem to be mediated by inflammatory markers. Additionally, the anti-inflammatory effects observed in the brain of WKY after tDCS needs to be further explored. Copyright © 2018 Elsevier Inc. All rights reserved.

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.

A Simple and Accurate Model to Predict Responses to Multi-electrode Stimulation in the Retina

PubMed Central

Maturana, Matias I.; Apollo, Nicholas V.; Hadjinicolaou, Alex E.; Garrett, David J.; Cloherty, Shaun L.; Kameneva, Tatiana; Grayden, David B.; Ibbotson, Michael R.; Meffin, Hamish

2016-01-01

Implantable electrode arrays are widely used in therapeutic stimulation of the nervous system (e.g. cochlear, retinal, and cortical implants). Currently, most neural prostheses use serial stimulation (i.e. one electrode at a time) despite this severely limiting the repertoire of stimuli that can be applied. Methods to reliably predict the outcome of multi-electrode stimulation have not been available. Here, we demonstrate that a linear-nonlinear model accurately predicts neural responses to arbitrary patterns of stimulation using in vitro recordings from single retinal ganglion cells (RGCs) stimulated with a subretinal multi-electrode array. In the model, the stimulus is projected onto a low-dimensional subspace and then undergoes a nonlinear transformation to produce an estimate of spiking probability. The low-dimensional subspace is estimated using principal components analysis, which gives the neuron’s electrical receptive field (ERF), i.e. the electrodes to which the neuron is most sensitive. Our model suggests that stimulation proportional to the ERF yields a higher efficacy given a fixed amount of power when compared to equal amplitude stimulation on up to three electrodes. We find that the model captures the responses of all the cells recorded in the study, suggesting that it will generalize to most cell types in the retina. The model is computationally efficient to evaluate and, therefore, appropriate for future real-time applications including stimulation strategies that make use of recorded neural activity to improve the stimulation strategy. PMID:27035143

Modulating phonemic fluency performance in healthy subjects with transcranial magnetic stimulation over the left or right lateral frontal cortex.

PubMed

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

2017-07-28

A growing body of evidence have suggested that non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can improve the performance of aphasic patients in language tasks. For example, application of inhibitory rTMS or tDCs over the right frontal lobe of dysphasic patients resulted in improved naming abilities. Several studies have also reported that in healthy controls (HC) tDCS application over the left prefrontal cortex (PFC) improve performance in naming and semantic fluency tasks. The aim of this study was to investigate in HC, for the first time, the effects of inhibitory repetitive TMS (rTMS) over left and right lateral frontal cortex (BA 47) on two phonemic fluency tasks (FAS or FPL). 44 right-handed HCs were administered rTMS or sham over the left or right lateral frontal cortex in two separate testing sessions, with a 24h interval, followed by the two phonemic fluency tasks. To account for possible practice effects, an additional 22 HCs were tested on only the phonemic fluency task across two sessions with no stimulation. We found that rTMS-inhibition over the left lateral frontal cortex significantly worsened phonemic fluency performance when compared to sham. In contrast, rTMS-inhibition over the right lateral frontal cortex significantly improved phonemic fluency performance when compared to sham. These results were not accounted for practice effects. We speculated that rTMS over the right lateral frontal cortex may induce plastic neural changes to the left lateral frontal cortex by suppressing interhemispheric inhibitory interactions. This resulted in an increased excitability (disinhibition) of the contralateral unstimulated left lateral frontal cortex, consequently enhancing phonemic fluency performance. Conversely, application of rTMS over the left lateral frontal cortex may induce a temporary, virtual lesion, with effects similar to those reported in left frontal patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components

NASA Astrophysics Data System (ADS)

Müller-Putz, Gernot R.; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert

2005-12-01

Brain-computer interfaces (BCIs) can be realized on the basis of steady-state evoked potentials (SSEPs). These types of brain signals resulting from repetitive stimulation have the same fundamental frequency as the stimulation but also include higher harmonics. This study investigated how the classification accuracy of a 4-class BCI system can be improved by incorporating visually evoked harmonic oscillations. The current study revealed that the use of three SSVEP harmonics yielded a significantly higher classification accuracy than was the case for one or two harmonics. During feedback experiments, the five subjects investigated reached a classification accuracy between 42.5% and 94.4%.

Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components.

PubMed

Müller-Putz, Gernot R; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert

2005-12-01

Brain-computer interfaces (BCIs) can be realized on the basis of steady-state evoked potentials (SSEPs). These types of brain signals resulting from repetitive stimulation have the same fundamental frequency as the stimulation but also include higher harmonics. This study investigated how the classification accuracy of a 4-class BCI system can be improved by incorporating visually evoked harmonic oscillations. The current study revealed that the use of three SSVEP harmonics yielded a significantly higher classification accuracy than was the case for one or two harmonics. During feedback experiments, the five subjects investigated reached a classification accuracy between 42.5% and 94.4%.

Electrophysiological Basis of Fecal Incontinence and Its Implications for Treatment

PubMed Central

2017-01-01

The majority of patients with neuropathic incontinence and other pelvic floor conditions associated with straining at stool have damage to the pudendal nerves distal to the ischial spine. Sacral nerve stimulation appears to be a promising innovation and has been widely adopted and currently considered the standard of care for adults with moderate to severe fecal incontinence and following failed sphincter repair. From a decision-to-treat perspective, the short-term efficacy is good (70%–80%), but the long-term efficacy of sacral nerve stimulation is around 50%. Newer electrophysiological tests and improved anal endosonography would more effectively guide clinical decision making. PMID:29159162

Motor cortex stimulation does not lead to functional recovery after experimental cortical injury in rats.

PubMed

Schönfeld, Lisa-Maria; Jahanshahi, Ali; Lemmens, Evi; Bauwens, Matthias; Hescham, Sarah-Anna; Schipper, Sandra; Lagiere, Melanie; Hendrix, Sven; Temel, Yasin

2017-01-01

Motor impairments are among the major complications that develop after cortical damage caused by either stroke or traumatic brain injury. Motor cortex stimulation (MCS) can improve motor functions in animal models of stroke by inducing neuroplasticity. In the current study, the therapeutic effect of chronic MCS was assessed in a rat model of severe cortical damage. A controlled cortical impact (CCI) was applied to the forelimb area of the motor cortex followed by implantation of a flat electrode covering the lesioned area. Forelimb function was assessed using the Montoya staircase test and the cylinder test before and after a period of chronic MCS. Furthermore, the effect of MCS on tissue metabolism and lesion size was measured using [18F]-fluorodesoxyglucose (FDG) μPET scanning. CCI caused a considerable lesion at the level of the motor cortex and dorsal striatum together with a long-lasting behavioral phenotype of forelimb impairment. However, MCS applied to the CCI lesion did not lead to any improvement in limb functioning when compared to non-stimulated control rats. Also, MCS neither changed lesion size nor distribution of FDG. The use of MCS as a standalone treatment did not improve motor impairments in a rat model of severe cortical damage using our specific treatment modalities.

Transcranial direct current stimulation as a memory enhancer in patients with Alzheimer's disease: a randomized, placebo-controlled trial.

PubMed

Bystad, Martin; Grønli, Ole; Rasmussen, Ingrid Daae; Gundersen, Nina; Nordvang, Lene; Wang-Iversen, Henrik; Aslaksen, Per M

2016-03-23

The purpose of this study was to assess the efficacy of transcranial direct current stimulation (tDCS) on verbal memory function in patients with Alzheimer's disease. We conducted a randomized, placebo-controlled clinical trial in which tDCS was applied in six 30-minute sessions for 10 days. tDCS was delivered to the left temporal cortex with 2-mA intensity. A total of 25 patients with Alzheimer's disease were enrolled in the study. All of the patients were diagnosed according to National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer's Disease and Related Disorders Association criteria. Twelve patients received active stimulation, and thirteen patients received placebo stimulation. The primary outcome measure was the change in two parallel versions of the California Verbal Learning Test-Second Edition, a standardized neuropsychological memory test normalized by age and gender. The secondary outcome measures were the Mini Mental State Examination, clock-drawing test, and Trail Making Test A and B. Changes in the California Verbal Learning Test-Second Edition scores were not significantly different between the active and placebo stimulation groups for immediate recall (p = 0.270), delayed recall (p = 0.052), or recognition (p = 0.089). There were nonsignificant differences in score changes on the Mini Mental State Examination (p = 0.799), clock-drawing test (p = 0.378), and Trail Making Test A (p = 0.288) and B (p = 0.093). Adverse effects were not observed. Compared with placebo stimulation, active tDCS stimulation in this clinical trial did not significantly improve verbal memory function in Alzheimer's disease. This study differs from previous studies in terms of the stimulation protocol, trial design, and application of standardized neuropsychological memory assessment. ClinicalTrials.gov identifier NCT02518412 . Registered on 10 August 2015.

Synchronizing theta oscillations with direct-current stimulation strengthens adaptive control in the human brain.

PubMed

Reinhart, Robert M G; Zhu, Julia; Park, Sohee; Woodman, Geoffrey F

2015-07-28

Executive control and flexible adjustment of behavior following errors are essential to adaptive functioning. Loss of adaptive control may be a biomarker of a wide range of neuropsychiatric disorders, particularly in the schizophrenia spectrum. Here, we provide support for the view that oscillatory activity in the frontal cortex underlies adaptive adjustments in cognitive processing following errors. Compared with healthy subjects, patients with schizophrenia exhibited low frequency oscillations with abnormal temporal structure and an absence of synchrony over medial-frontal and lateral-prefrontal cortex following errors. To demonstrate that these abnormal oscillations were the origin of the impaired adaptive control in patients with schizophrenia, we applied noninvasive dc electrical stimulation over the medial-frontal cortex. This noninvasive stimulation descrambled the phase of the low-frequency neural oscillations that synchronize activity across cortical regions. Following stimulation, the behavioral index of adaptive control was improved such that patients were indistinguishable from healthy control subjects. These results provide unique causal evidence for theories of executive control and cortical dysconnectivity in schizophrenia.

Electrical stimulation for gastroesophageal reflux disease: current state of the art.

PubMed

Kim, Sharon E; Soffer, Edy

2016-01-01

Patients with gastroesophageal reflux disease (GERD) who are not satisfied with acid suppression therapy can benefit primarily from fundoplication, a surgical intervention. Fundoplication has been the standard surgical procedure for GERD. It is effective but is associated with adverse effects, resulting in a declining number of interventions, creating a need for alternative interventions that are effective, yet have a better adverse effect profile. One such alternative involves the application of electrical stimulation to the lower esophageal sphincter. A number of animal studies showed that such stimulation can increase resting lower esophageal sphincter pressure. An acute human study confirmed this effect, and was followed by two open-label studies, with a follow-up of up to 3 years. Results thus far show that the therapy is associated with a significant improvement in symptoms, a significant reduction in esophageal acid exposure, and a very good safety profile. This review will describe the evolution of electrical stimulation therapy for GERD, as well as the safety and efficacy of this intervention.

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.

Auditory midbrain implant: a review.

PubMed

Lim, Hubert H; Lenarz, Minoo; Lenarz, Thomas

2009-09-01

The auditory midbrain implant (AMI) is a new hearing prosthesis designed for stimulation of the inferior colliculus in deaf patients who cannot sufficiently benefit from cochlear implants. The authors have begun clinical trials in which five patients have been implanted with a single shank AMI array (20 electrodes). The goal of this review is to summarize the development and research that has led to the translation of the AMI from a concept into the first patients. This study presents the rationale and design concept for the AMI as well a summary of the animal safety and feasibility studies that were required for clinical approval. The authors also present the initial surgical, psychophysical, and speech results from the first three implanted patients. Overall, the results have been encouraging in terms of the safety and functionality of the implant. All patients obtain improvements in hearing capabilities on a daily basis. However, performance varies dramatically across patients depending on the implant location within the midbrain with the best performer still not able to achieve open set speech perception without lip-reading cues. Stimulation of the auditory midbrain provides a wide range of level, spectral, and temporal cues, all of which are important for speech understanding, but they do not appear to sufficiently fuse together to enable open set speech perception with the currently used stimulation strategies. Finally, several issues and hypotheses for why current patients obtain limited speech perception along with several feasible solutions for improving AMI implementation are presented.

Fractal Interfaces for Stimulating and Recording Neural Implants

NASA Astrophysics Data System (ADS)

Watterson, William James

From investigating movement in an insect to deciphering cognition in a human brain to treating Parkinson's disease, hearing loss, or even blindness, electronic implants are an essential tool for understanding the brain and treating neural diseases. Currently, the stimulating and recording resolution of these implants remains low. For instance, they can record all the neuron activity associated with movement in an insect, but are quite far from recording, at an individual neuron resolution, the large volumes of brain tissue associated with cognition. Likewise, there is remarkable success in the cochlear implant restoring hearing due to the relatively simple anatomy of the auditory nerves, but are failing to restore vision to the blind due to poor signal fidelity and transmission in stimulating the more complex anatomy of the visual nerves. The critically important research needed to improve the resolution of these implants is to optimize the neuron-electrode interface. This thesis explores geometrical and material modifications to both stimulating and recording electrodes which can improve the neuron-electrode interface. First, we introduce a fractal electrode geometry which radically improves the restored visual acuity achieved by retinal implants and leads to safe, long-term operation of the implant. Next, we demonstrate excellent neuron survival and neurite outgrowth on carbon nanotube electrodes, thus providing a safe biomaterial which forms a strong connection between the electrode and neurons. Additional preliminary evidence suggests carbon nanotubes patterned into a fractal geometry will provide further benefits in improving the electrode-neuron interface. Finally, we propose a novel implant based off field effect transistor technology which utilizes an interconnecting fractal network of semiconducting carbon nanotubes to record from thousands of neurons simutaneously at an individual neuron resolution. Taken together, these improvements have the potential to radically improve our understanding of the brain and our ability to restore function to patients of neural diseases.

The short- and long-term benefit in chronic low back pain through adjuvant electrical versus manual auricular acupuncture.

PubMed

Sator-Katzenschlager, Sabine M; Scharbert, Gisela; Kozek-Langenecker, Sibylle A; Szeles, Jozef C; Finster, Gabriele; Schiesser, Andreas W; Heinze, Georg; Kress, Hans Georg

2004-05-01

Acupuncture is an established adjuvant analgesic modality for the treatment of chronic pain. Electrical stimulation of acupuncture points is considered to increase acupuncture analgesia. In this prospective, randomized, double-blind, controlled study we tested the hypothesis that auricular electroacupuncture (EA) relieves pain more effectively than conventional manual auricular acupuncture (CO) in chronic low back pain patients with insufficient pain relief (visual analogue scale [VAS] > or = 5) treated with standardized analgesic therapy. Disposable acupuncture needles were inserted in the auricular acupuncture points 29, 40, and 55 of the dominant side and connected to a newly developed battery-powered miniaturized stimulator worn behind the ear. Patients were randomized into group EA (n = 31) with continuous low-frequency auricular EA (1 Hz biphasic constant current of 2 mA) and group CO (n = 30) without electrical stimulation (sham-electroacupuncture). Treatment was performed once weekly for 6 wk, and in each group needles were withdrawn 48 h after insertion. During the study period and a 3-mo follow-up, patients were asked to complete the McGill questionnaire. Psychological well being, activity level, quality of sleep, and pain intensity were assessed by means of VAS; moreover, analgesic drug consumption was documented. Pain relief was significantly better in group EA during the study and the follow-up period as compared with group CO. Similarly, psychological well-being, activity, and sleep were significantly improved in group EA versus group CO, the consumption of analgesic rescue medication was less, and more patients returned to full-time employment. Neuropathic pain in particular improved in patients treated with EA. There were no adverse side effects. These results are the first to demonstrate that continuous EA stimulation of auricular acupuncture points improves the treatment of chronic low back pain in an outpatient population. Continuous electrical stimulation of auricular acupuncture points using the new point stimulation device P-stim significantly decreases pain intensity and improves psychological well-being, activity, and sleep in chronic low back pain patients.

Cognitive effects of transcranial direct current stimulation in depression: Results from the SELECT-TDCS trial and insights for further clinical trials.

PubMed

Brunoni, André Russowsky; Tortella, Gabriel; Benseñor, Isabela Martins; Lotufo, Paulo Andrade; Carvalho, André Ferrer; Fregni, Felipe

2016-09-15

Cognitive dysfunction treatment remains an unmet clinical need in major depressive disorder (MDD). Transcranial direct current stimulation (tDCS) may improve cognitive symptoms in MDD. Our aim was to investigate the cognitive effects of tDCS in the Sertraline vs. Electric Current Therapy for Treating Depression Clinical Study (SELECT-TDCS). We also explored whether tDCS could have mood-independent cognitive effects. One hundred twenty MDD patients aged from 18 to 65 years received 12 sessions of active/sham tDCS (2mA for 30min) and real/placebo 50mg/d sertraline over 6 weeks in a factorial trial. We analyzed whether changes in performance of neuropsychological tests (Trail Making, Digit Span, Stroop Task, Mini-Mental Status Exam and Montreal Cognitive Assessment) occurred over time, according to treatment group and depression improvement. Exploratory analyses were carried out to verify the influence of clinical and demographic variables on the outcomes. Cognitive improvement was showed in most tests used, although they occurred regardless of intervention type and depression improvement. Further exploratory analyses revealed that clinical response and education level could have mediated pro-cognitive tDCS effects on some of the tests used. The neuropsychological battery used might not have been sensitive to detect tDCS-induced effects on cognition. Lack of simultaneous cognitive training during application may have also limited its cognitive effects. We found no evidence of beneficial or deleterious cognitive effects of tDCS as a treatment for depression. We discussed clinical trial design considerations for further tDCS studies assessing cognitive effects, including sample and outcomes considerations. Copyright © 2016 Elsevier B.V. All rights reserved.

Tissue resistivities determine the current flow in the cochlea.

PubMed

Micco, Alan Gerard; Richter, Claus-Peter

2006-10-01

In individuals with severe to profound hearing loss, cochlear implants bypass normal inner ear function by applying electrical current directly into the cochlea, thereby stimulating cochlear nerve fibers. Stimulating discrete populations of spiral ganglion cells in cochlear implant users' ears is similar to the encoding of small acoustic frequency bands in a normal-hearing person's ear. Thus, spiral ganglion cells stimulated by an electrode convey the information contained by a small acoustic frequency band. Problems that refer to the current spread and subsequent nonselective stimulation of spiral ganglion cells in the cochlea are reviewed. Cochlear anatomy and tissue properties determine the current path in the cochlea. Current spreads largely via scala tympani and across turns. While most of the current leaves the cochlea via the modiolus, the facial canal and the round window constitute additional natural escape paths for the current from the cochlea. Moreover, degenerative processes change tissue resistivities and thus may affect current spread in the cochlea. Electrode design and coding strategies may result in more spatial stimulation of spiral ganglion cells, resulting in a better performance of the electrode-tissue interface.

Mitigation of stress: new treatment alternatives.

PubMed

Subhani, Ahmad Rauf; Kamel, Nidal; Mohamad Saad, Mohamad Naufal; Nandagopal, Nanda; Kang, Kenneth; Malik, Aamir Saeed

2018-02-01

Complaints of stress are common in modern life. Psychological stress is a major cause of lifestyle-related issues, contributing to poor quality of life. Chronic stress impedes brain function, causing impairment of many executive functions, including working memory, decision making and attentional control. The current study sought to describe newly developed stress mitigation techniques, and their influence on autonomic and endocrine functions. The literature search revealed that the most frequently studied technique for stress mitigation was biofeedback (BFB). However, evidence suggests that neurofeedback (NFB) and noninvasive brain stimulation (NIBS) could potentially provide appropriate approaches. We found that recent studies of BFB methods have typically used measures of heart rate variability, respiration and skin conductance. In contrast, studies of NFB methods have typically utilized neurocomputation techniques employing electroencephalography, functional magnetic resonance imaging and near infrared spectroscopy. NIBS studies have typically utilized transcranial direct current stimulation methods. Mitigation of stress is a challenging but important research target for improving quality of life.

Combining Upper Limb Robotic Rehabilitation with Other Therapeutic Approaches after Stroke: Current Status, Rationale, and Challenges

PubMed Central

Grosmaire, Anne Gaëlle; Battini, Elena

2017-01-01

A better understanding of the neural substrates that underlie motor recovery after stroke has led to the development of innovative rehabilitation strategies and tools that incorporate key elements of motor skill relearning, that is, intensive motor training involving goal-oriented repeated movements. Robotic devices for the upper limb are increasingly used in rehabilitation. Studies have demonstrated the effectiveness of these devices in reducing motor impairments, but less so for the improvement of upper limb function. Other studies have begun to investigate the benefits of combined approaches that target muscle function (functional electrical stimulation and botulinum toxin injections), modulate neural activity (noninvasive brain stimulation), and enhance motivation (virtual reality) in an attempt to potentialize the benefits of robot-mediated training. The aim of this paper is to overview the current status of such combined treatments and to analyze the rationale behind them. PMID:29057269

Noninvasive transcranial direct current stimulation (tDCS) for the treatment of orofacial pain.

PubMed

Fricova, Jitka; Englerova, Katerina; Rokyta, Richard

2016-10-01

tDCS is a promising method for the treatment of chronic pain. Electrode placement locations must be chosen in accordance with the density and the time course of the current in order to prevent pathological changes in the underlying tissue. In order to reduce current spatial variability, more electrodes of the same polarity are placed in a circle around the second electrode of the opposite polarity. The applied current produced the greatest changes directly beneath the electrodes: the cathode reduces the excitability of cortical neurons, while the anode has the opposite effect. Based on inclusion criteria, 10 patients with chronic orofacial pain, secondary trigeminal neuralgia after oral surgery, were enrolled and underwent both anode and cathode stimulation. Before the first session we measured pain intensity on a numeric pain rating scale and tactile and thermal stimulation were used to assess somatosensory status. tDCS was applied for five consecutive days. At the end of tDCS application, somatosensory status was assessed again. From our results we can conclude that the application of tDCS improves the perception of some types of pain. When we increase our sample size, we would expect confirmation not only on our positive results, but also some additional findings for explaining the pathophysiology of orofacial pain. These pathophysiological findings and explanations are very important for the application of tDCS in the treatment of orofacial pain and also for other types of neuropathic pain.

Effects of non-invasive brain stimulation on associative memory

DOE PAGES

Matzen, Laura E.; Trumbo, Michael C.; Leach, Ryan C.; ...

2015-07-30

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer’s disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recallmore » tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 minutes, 2 mA) or sham (30 minutes, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions.« less

Effects of non-invasive brain stimulation on associative memory.

PubMed

Matzen, Laura E; Trumbo, Michael C; Leach, Ryan C; Leshikar, Eric D

2015-10-22

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer's disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recall tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 min, 2 mA) or sham (30 min, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of non-invasive brain stimulation on associative memory

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

Matzen, Laura E.; Trumbo, Michael C.; Leach, Ryan C.

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer’s disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recallmore » tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 minutes, 2 mA) or sham (30 minutes, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions.« less

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.

One-shot percutaneous electrical nerve stimulation vs. transcutaneous electrical nerve stimulation for low back pain: comparison of therapeutic effects.

PubMed

Hsieh, Ru-Lan; Lee, Wen-Chung

2002-11-01

To investigate the therapeutic effects of one shot of low-frequency percutaneous electrical nerve stimulation one shot of transcutaneous electrical nerve stimulation in patients with low back pain. In total, 133 low back pain patients were recruited for this randomized, control study. Group 1 patients received medication only. Group 2 patients received medication plus one shot of percutaneous electrical nerve stimulation. Group 3 patients received medication plus one shot of transcutaneous electrical nerve stimulation. Therapeutic effects were measured using a visual analog scale, body surface score, pain pressure threshold, and the Quebec Back Pain Disability Scale. Immediately after one-shot treatment, the visual analog scale improved 1.53 units and the body surface score improved 3.06 units in the percutaneous electrical nerve stimulation group. In the transcutaneous electrical nerve stimulation group, the visual analog scale improved 1.50 units and the body surface score improved 3.98 units. The improvements did not differ between the two groups. There were no differences in improvement at 3 days or 1 wk after the treatment among the three groups. Simple one-shot treatment with percutaneous electrical nerve stimulation or transcutaneous electrical nerve stimulation provided immediate pain relief for low back pain patients. One-shot transcutaneous electrical nerve stimulation treatment is recommended due to the rarity of side effects and its convenient application.

Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease.

PubMed

Ramirez de Noriega, Fernando; Eitan, Renana; Marmor, Odeya; Lavi, Adi; Linetzky, Eduard; Bergman, Hagai; Israel, Zvi

2015-02-18

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Motor efficacy and safety have been established for constant voltage (CV) devices and more recently for constant current (CC) devices. CC devices adjust output voltage to provide CC stimulation irrespective of impedance fluctuation, while the current applied by CV stimulation depends on the impedance that may change over time. No study has directly compared the clinical effects of these two stimulation modalities. Objective: To compare the safety and clinical impact of CC STN DBS to CV STN DBS in patients with advanced PD 2 years after surgery. Methods: Patients were eligible for inclusion if they had undergone STN DBS surgery for idiopathic PD, had been implanted with a Medtronic Activa PC and if their stimulation program and medication had been stable for at least 1 year. This single-center trial was designed as a double-blind, randomized, prospective study with crossover after 2 weeks. Motor equivalence of the 2 modalities was confirmed utilizing part III of the Unified Parkinson's Disease Rating Scale (UPDRS). PD diaries and multiple subjective and objective evaluations of quality of life, depression, cognition and emotional processing were evaluated on both CV and on CC stimulation. Analysis using the paired t test with Bonferroni correction for multiple comparisons was performed to identify any significant difference between the stimulation modalities. Results: 8 patients were recruited (6 men, 2 women); 1 patient did not complete the study. The average age at surgery was 56.7 years (range 47-63). Disease duration at the time of surgery was 7.5 years (range 3-12). Patients were recruited 23.8 months (range 22.5-24) after surgery. At the postoperative study baseline, this patient group showed an average motor improvement of 69% (range 51-97) as measured by the change in UPDRS part III with stimulation alone. Levodopa equivalent medication was reduced on average by 67% (range 15-88). Patients were poorly compliant with PD diaries, and these did not yield useful information. The minor deterioration in quality-of-life scores (Parkinson's Disease Questionnaire-39, Quality of Life Enjoyment and Satisfaction Questionnaire) with CC stimulation were not statistically significant. Two measures of depression (Hamilton Rating Scale D17, Quick Inventory of Depressive Symptomatology - Self-Report) showed a nonsignificant lower score (less depression) with CC stimulation, but a third (Beck Depression Inventory) showed equivalence. Cognitive testing (Mini Mental State Examination) and emotional processing (Montreal Affective Voices) were equivalent for CC and CV. Conclusion: CC STN DBS is safe. For equivalent motor efficacy, no significant difference could be identified between CC and CV stimulation for nonmotor evaluations in PD patients 2 years after surgery. © 2015 S. Karger AG, Basel.

Plant Metabolomics: An Indispensable System Biology Tool for Plant Science

PubMed Central

Hong, Jun; Yang, Litao; Zhang, Dabing; Shi, Jianxin

2016-01-01

As genomes of many plant species have been sequenced, demand for functional genomics has dramatically accelerated the improvement of other omics including metabolomics. Despite a large amount of metabolites still remaining to be identified, metabolomics has contributed significantly not only to the understanding of plant physiology and biology from the view of small chemical molecules that reflect the end point of biological activities, but also in past decades to the attempts to improve plant behavior under both normal and stressed conditions. Hereby, we summarize the current knowledge on the genetic and biochemical mechanisms underlying plant growth, development, and stress responses, focusing further on the contributions of metabolomics to practical applications in crop quality improvement and food safety assessment, as well as plant metabolic engineering. We also highlight the current challenges and future perspectives in this inspiring area, with the aim to stimulate further studies leading to better crop improvement of yield and quality. PMID:27258266

Plant Metabolomics: An Indispensable System Biology Tool for Plant Science.

PubMed

Hong, Jun; Yang, Litao; Zhang, Dabing; Shi, Jianxin

2016-06-01

As genomes of many plant species have been sequenced, demand for functional genomics has dramatically accelerated the improvement of other omics including metabolomics. Despite a large amount of metabolites still remaining to be identified, metabolomics has contributed significantly not only to the understanding of plant physiology and biology from the view of small chemical molecules that reflect the end point of biological activities, but also in past decades to the attempts to improve plant behavior under both normal and stressed conditions. Hereby, we summarize the current knowledge on the genetic and biochemical mechanisms underlying plant growth, development, and stress responses, focusing further on the contributions of metabolomics to practical applications in crop quality improvement and food safety assessment, as well as plant metabolic engineering. We also highlight the current challenges and future perspectives in this inspiring area, with the aim to stimulate further studies leading to better crop improvement of yield and quality.

Augmented cartilage regeneration by implantation of cellular versus acellular implants after bone marrow stimulation: a systematic review and meta-analysis of animal studies

PubMed Central

van Kuppevelt, Toin H.; Gonzales, Veronica K.; Buma, Pieter; IntHout, Joanna; de Vries, Rob B.M.

2017-01-01

Bone marrow stimulation may be applied to regenerate focal cartilage defects, but generally results in transient clinical improvement and formation of fibrocartilage rather than hyaline cartilage. Tissue engineering and regenerative medicine strive to develop new solutions to regenerate hyaline cartilage tissue. This systematic review and meta-analysis provides a comprehensive overview of current literature and assesses the efficacy of articular cartilage regeneration by implantation of cell-laden versus cell-free biomaterials in the knee and ankle joint in animals after bone marrow stimulation. PubMed and EMBASE (via OvidSP) were systematically searched using tissue engineering, cartilage and animals search strategies. Included were primary studies in which cellular and acellular biomaterials were implanted after applying bone marrow stimulation in the knee or ankle joint in healthy animals. Study characteristics were tabulated and outcome data were collected for meta-analysis for studies applying semi-quantitative histology as outcome measure (117 studies). Cartilage regeneration was expressed on an absolute 0–100% scale and random effects meta-analyses were performed. Implantation of cellular biomaterials significantly improved cartilage regeneration by 18.6% compared to acellular biomaterials. No significant differences were found between biomaterials loaded with stem cells and those loaded with somatic cells. Culture conditions of cells did not affect cartilage regeneration. Cartilage formation was reduced with adipose-derived stem cells compared to other cell types, but still improved compared to acellular scaffolds. Assessment of the risk of bias was impaired due to incomplete reporting for most studies. Implantation of cellular biomaterials improves cartilage regeneration compared to acellular biomaterials. PMID:29093996

Cognitive Enhancement or Cognitive Cost: Trait-Specific Outcomes of Brain Stimulation in the Case of Mathematics Anxiety

PubMed Central

Sarkar, Amar; Dowker, Ann

2014-01-01

The surge in noninvasive brain stimulation studies investigating cognitive enhancement has neglected the effect of interindividual differences, such as traits, on stimulation outcomes. Using the case of mathematics anxiety in a sample of healthy human participants in a placebo-controlled, double-blind, crossover experiment, we show that identical transcranial direct current stimulation (tDCS) exerts opposite behavioral and physiological effects depending on individual trait levels. Mathematics anxiety is the negative emotional response elicited by numerical tasks, impairing mathematical achievement. tDCS was applied to the dorsolateral prefrontal cortex, a frequent target for modulating emotional regulation. It improved reaction times on simple arithmetic decisions and decreased cortisol concentrations (a biomarker of stress) in high mathematics anxiety individuals. In contrast, tDCS impaired reaction times for low mathematics anxiety individuals and prevented a decrease in cortisol concentration compared with sham stimulation. Both groups showed a tDCS-induced side effect—impaired executive control in a flanker task—a cognitive function subserved by the stimulated region. These behavioral and physiological double dissociations have implications for brain stimulation research by highlighting the role of individual traits in experimental findings. Brain stimulation clearly does not produce uniform benefits, even applied in the same configuration during the same tasks, but may interact with traits to produce markedly opposed outcomes. PMID:25505313

Cognitive enhancement or cognitive cost: trait-specific outcomes of brain stimulation in the case of mathematics anxiety.

PubMed

Sarkar, Amar; Dowker, Ann; Cohen Kadosh, Roi

2014-12-10

The surge in noninvasive brain stimulation studies investigating cognitive enhancement has neglected the effect of interindividual differences, such as traits, on stimulation outcomes. Using the case of mathematics anxiety in a sample of healthy human participants in a placebo-controlled, double-blind, crossover experiment, we show that identical transcranial direct current stimulation (tDCS) exerts opposite behavioral and physiological effects depending on individual trait levels. Mathematics anxiety is the negative emotional response elicited by numerical tasks, impairing mathematical achievement. tDCS was applied to the dorsolateral prefrontal cortex, a frequent target for modulating emotional regulation. It improved reaction times on simple arithmetic decisions and decreased cortisol concentrations (a biomarker of stress) in high mathematics anxiety individuals. In contrast, tDCS impaired reaction times for low mathematics anxiety individuals and prevented a decrease in cortisol concentration compared with sham stimulation. Both groups showed a tDCS-induced side effect-impaired executive control in a flanker task-a cognitive function subserved by the stimulated region. These behavioral and physiological double dissociations have implications for brain stimulation research by highlighting the role of individual traits in experimental findings. Brain stimulation clearly does not produce uniform benefits, even applied in the same configuration during the same tasks, but may interact with traits to produce markedly opposed outcomes. Copyright © 2014 Sarkar et al.

Focused intracochlear electric stimulation with phased array channels.

PubMed

van den Honert, Chris; Kelsall, David C

2007-06-01

A method is described for producing focused intracochlear electric stimulation using an array of N electrodes. For each electrode site, N weights are computed that define the ratios of positive and negative electrode currents required to produce cancellation of the voltage within scala tympani at all of the N-1 other sites. Multiple sites can be stimulated simultaneously by superposition of their respective current vectors. The method allows N independent stimulus waveforms to be delivered to each of the N electrode sites without spatial overlap. Channel interaction from current spread associated with monopolar stimulation is substantially eliminated. The method operates by inverting the spread functions of individual monopoles as measured with the other electrodes. The method was implemented and validated with data from three human subjects implanted with 22-electrode perimodiolar arrays. Results indicate that (1) focusing is realizable with realistic precision; (2) focusing comes at the cost of increased total stimulation current; (3) uncanceled voltages that arise beyond the ends of the array are weak except when stimulating the two end channels; and (4) close perimodiolar positioning of the electrodes may be important for minimizing stimulation current and sensitivity to measurement errors.

Optimal Pulse Configuration Design for Heart Stimulation. A Theoretical, Numerical and Experimental Study.

NASA Astrophysics Data System (ADS)

Hardy, Neil; Dvir, Hila; Fenton, Flavio

Existing pacemakers consider the rectangular pulse to be the optimal form of stimulation current. However, other waveforms for the use of pacemakers could save energy while still stimulating the heart. We aim to find the optimal waveform for pacemaker use, and to offer a theoretical explanation for its advantage. Since the pacemaker battery is a charge source, here we probe the stimulation current waveforms with respect to the total charge delivery. In this talk we present theoretical analysis and numerical simulations of myocyte ion-channel currents acting as an additional source of charge that adds to the external stimulating charge for stimulation purposes. Therefore, we find that as the action potential emerges, the external stimulating current can be reduced accordingly exponentially. We then performed experimental studies in rabbit and cat hearts and showed that indeed exponential truncated pulses with less total charge can still induce activation in the heart. From the experiments, we present curves showing the savings in charge as a function of exponential waveform and we calculated that the longevity of the pacemaker battery would be ten times higher for the exponential current compared to the rectangular waveforms. Thanks to Petit Undergraduate Research Scholars Program and NSF# 1413037.

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.

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.

Reading Visual Braille with a Retinal Prosthesis

PubMed Central

Lauritzen, Thomas Z.; Harris, Jordan; Mohand-Said, Saddek; Sahel, Jose A.; Dorn, Jessy D.; McClure, Kelly; Greenberg, Robert J.

2012-01-01

Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome. This study investigates the possibility of using an epiretinal prosthesis to stimulate visual braille as a sensory substitution for reading written letters and words. The Argus II retinal prosthesis system, used in this study, includes a 10 × 6 electrode array implanted epiretinally, a tiny video camera mounted on a pair of glasses, and a wearable computer that processes the video and determines the stimulation current of each electrode in real time. In the braille reading system, individual letters are created by a subset of dots from a 3 by 2 array of six dots. For the visual braille experiment, a grid of six electrodes was chosen out of the 10 × 6 Argus II array. Groups of these electrodes were then directly stimulated (bypassing the camera) to create visual percepts of individual braille letters. Experiments were performed in a single subject. Single letters were stimulated in an alternative forced choice (AFC) paradigm, and short 2–4-letter words were stimulated (one letter at a time) in an open-choice reading paradigm. The subject correctly identified 89% of single letters, 80% of 2-letter, 60% of 3-letter, and 70% of 4-letter words. This work suggests that text can successfully be stimulated and read as visual braille in retinal prosthesis patients. PMID:23189036

Reading visual braille with a retinal prosthesis.

PubMed

Lauritzen, Thomas Z; Harris, Jordan; Mohand-Said, Saddek; Sahel, Jose A; Dorn, Jessy D; McClure, Kelly; Greenberg, Robert J

2012-01-01

Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome. This study investigates the possibility of using an epiretinal prosthesis to stimulate visual braille as a sensory substitution for reading written letters and words. The Argus II retinal prosthesis system, used in this study, includes a 10 × 6 electrode array implanted epiretinally, a tiny video camera mounted on a pair of glasses, and a wearable computer that processes the video and determines the stimulation current of each electrode in real time. In the braille reading system, individual letters are created by a subset of dots from a 3 by 2 array of six dots. For the visual braille experiment, a grid of six electrodes was chosen out of the 10 × 6 Argus II array. Groups of these electrodes were then directly stimulated (bypassing the camera) to create visual percepts of individual braille letters. Experiments were performed in a single subject. Single letters were stimulated in an alternative forced choice (AFC) paradigm, and short 2-4-letter words were stimulated (one letter at a time) in an open-choice reading paradigm. The subject correctly identified 89% of single letters, 80% of 2-letter, 60% of 3-letter, and 70% of 4-letter words. This work suggests that text can successfully be stimulated and read as visual braille in retinal prosthesis patients.

A neurochemical closed-loop controller for deep brain stimulation: toward individualized smart neuromodulation therapies.

PubMed

Grahn, Peter J; Mallory, Grant W; Khurram, Obaid U; Berry, B Michael; Hachmann, Jan T; Bieber, Allan J; Bennet, Kevin E; Min, Hoon-Ki; Chang, Su-Youne; Lee, Kendall H; Lujan, J L

2014-01-01

Current strategies for optimizing deep brain stimulation (DBS) therapy involve multiple postoperative visits. During each visit, stimulation parameters are adjusted until desired therapeutic effects are achieved and adverse effects are minimized. However, the efficacy of these therapeutic parameters may decline with time due at least in part to disease progression, interactions between the host environment and the electrode, and lead migration. As such, development of closed-loop control systems that can respond to changing neurochemical environments, tailoring DBS therapy to individual patients, is paramount for improving the therapeutic efficacy of DBS. Evidence obtained using electrophysiology and imaging techniques in both animals and humans suggests that DBS works by modulating neural network activity. Recently, animal studies have shown that stimulation-evoked changes in neurotransmitter release that mirror normal physiology are associated with the therapeutic benefits of DBS. Therefore, to fully understand the neurophysiology of DBS and optimize its efficacy, it may be necessary to look beyond conventional electrophysiological analyses and characterize the neurochemical effects of therapeutic and non-therapeutic stimulation. By combining electrochemical monitoring and mathematical modeling techniques, we can potentially replace the trial-and-error process used in clinical programming with deterministic approaches that help attain optimal and stable neurochemical profiles. In this manuscript, we summarize the current understanding of electrophysiological and electrochemical processing for control of neuromodulation therapies. Additionally, we describe a proof-of-principle closed-loop controller that characterizes DBS-evoked dopamine changes to adjust stimulation parameters in a rodent model of DBS. The work described herein represents the initial steps toward achieving a "smart" neuroprosthetic system for treatment of neurologic and psychiatric disorders.

Contributions of the cerebellum and the motor cortex to acquisition and retention of motor memories

PubMed Central

Herzfeld, David J.; Pastor, Damien; Haith, Adrian M.; Rossetti, Yves; Shadmehr, Reza; O’Shea, Jacinta

2014-01-01

We investigated the contributions of the cerebellum and the motor cortex (M1) to acquisition and retention of human motor memories in a force field reaching task. We found that anodal transcranial direct current stimulation (tDCS) of the cerebellum, a technique that is thought to increase neuronal excitability, increased the ability to learn from error and form an internal model of the field, while cathodal cerebellar stimulation reduced this error-dependent learning. In addition, cathodal cerebellar stimulation disrupted the ability to respond to error within a reaching movement, reducing the gain of the sensory-motor feedback loop. By contrast, anodal M1 stimulation had no significant effects on these variables. During sham stimulation, early in training the acquired motor memory exhibited rapid decay in error-clamp trials. With further training the rate of decay decreased, suggesting that with training the motor memory was transformed from a labile to a more stable state. Surprisingly, neither cerebellar nor M1 stimulation altered these decay patterns. Participants returned 24 hours later and were re-tested in error-clamp trials without stimulation. The cerebellar group that had learned the task with cathodal stimulation exhibited significantly impaired retention, and retention was not improved by M1 anodal stimulation. In summary, non-invasive cerebellar stimulation resulted in polarity-dependent up- or down-regulation of error-dependent motor learning. In addition, cathodal cerebellar stimulation during acquisition impaired the ability to retain the motor memory overnight. Thus, in the force field task we found a critical role for the cerebellum in both formation of motor memory and its retention. PMID:24816533

Effects of High-Definition Anodal Transcranial Direct Current Stimulation Applied Simultaneously to Both Primary Motor Cortices on Bimanual Sensorimotor Performance

PubMed Central

Pixa, Nils H.; Steinberg, Fabian; Doppelmayr, Michael

2017-01-01

Many daily activities, such as tying one’s shoe laces, opening a jar of jam or performing a free throw in basketball, require the skillful coordinated use of both hands. Even though the non-invasive method of transcranial direct current stimulation (tDCS) has been repeatedly shown to improve unimanual motor performance, little is known about its effects on bimanual motor performance. More knowledge about how tDCS may improve bimanual behavior would be relevant to motor recovery, e.g., in persons with bilateral impairment of hand function. We therefore examined the impact of high-definition anodal tDCS (HD-atDCS) on the performance of a bimanual sequential sensorimotor task. Thirty-two volunteers (age M = 24.25; SD = 2.75; 14 females) participated in this double-blind study and performed sport stacking in six experimental sessions. In sport stacking, 12 specially designed cups must be stacked (stacked up) and dismantled (stacked down) in predefined patterns as fast as possible. During a pretest, posttest and follow-up test, two sport stacking formations (3-6-3 stack and 1-10-1 stack) were performed. Between the pretest and posttest, all participants were trained in sport stacking with concurrent brain stimulation for three consecutive days. The experimental group (STIM-M1) received HD-atDCS over both primary motor cortices (M1), while the control group received a sham stimulation (SHAM). Three-way analysis of variance (ANOVA) revealed a significant main effect of TIME and a significant interaction of TIME × GROUP. No significant effects were found for GROUP, nor for the three-way interaction of TIME × GROUP × FORMATION. Further two-way ANOVAs showed a significant main effect of TIME and a non-significant main effect for GROUP in both sport stacking formations. A significant interaction between TIME × GROUP was found only for the 3-6-3 formation, indicating superior performance gains for the experimental group (STIM-M1). To account and control for baseline influences on the outcome measurements, ANCOVAs treating pretest scores as covariates revealed a significant effect of the stimulation. From this, we conclude that bilateral HD-atDCS over both M1 improves motor performance in a bimanual sequential sensorimotor task. These results may indicate a beneficial use of tDCS for learning and recovery of bimanual motor skills. PMID:28747875

Reducing interaction in simultaneous paired stimulation with CI.

PubMed

Vellinga, Dirk; Bruijn, Saskia; Briaire, Jeroen J; Kalkman, Randy K; Frijns, Johan H M

2017-01-01

In this study simultaneous paired stimulation of electrodes in cochlear implants is investigated by psychophysical experiments in 8 post-lingually deaf subjects (and one extra subject who only participated in part of the experiments). Simultaneous and sequential monopolar stimulation modes are used as references and are compared to channel interaction compensation, partial tripolar stimulation and a novel sequential stimulation strategy named phased array compensation. Psychophysical experiments are performed to investigate both the loudness integration during paired stimulation at the main electrodes as well as the interaction with the electrode contact located halfway between the stimulating pair. The study shows that simultaneous monopolar stimulation has more loudness integration on the main electrodes and more interaction in between the electrodes than sequential stimulation. Channel interaction compensation works to reduce the loudness integration at the main electrodes, but does not reduce the interaction in between the electrodes caused by paired stimulation. Partial tripolar stimulation uses much more current to reach the needed loudness, but shows the same interaction in between the electrodes as sequential monopolar stimulation. In phased array compensation we have used the individual impedance matrix of each subject to calculate the current needed on each electrode to exactly match the stimulation voltage along the array to that of sequential stimulation. The results show that the interaction in between the electrodes is the same as monopolar stimulation. The strategy uses less current than partial tripolar stimulation, but more than monopolar stimulation. In conclusion, the paper shows that paired stimulation is possible if the interaction is compensated.

Forest genetics research at the University of Michigan

Treesearch

Burton V. Barnes

1970-01-01

The purpose of the research program, as evidenced by results as well as current research and future direction, is to add to the knowledge of the ecology and genetics of forest trees. Although we are interested in the practical gains that are possible and being realized in practical tree improvement, our contribution is in basic studies that stimulate and challenge...

An Investigation of Middle Grade Mathematics and Language Arts Teachers' Knowledge and Beliefs of Student Learning Objectives

ERIC Educational Resources Information Center

Miller, Zipporah A.

2017-01-01

Teacher evaluations in most school districts, until recently, have served as an exercise in compliance rather than a means to identify the strengths and weaknesses of each teacher in order to provide appropriate support to improve professional practice and increase student learning. Current federal legislation has stimulated districts to rethink…

PERSPECTIVE: Principles of design and biological approaches for improving the selectivity of cochlear implant electrodes

NASA Astrophysics Data System (ADS)

O'Leary, Stephen J.; Richardson, Rachael R.; McDermott, Hugh J.

2009-10-01

The perceptual performance of cochlear implant recipients seems to have reached a plateau in recent years. This may be attributable to inadequate neural selectivity of available intracochlear electrodes, caused by current spread and electrode interactions. Attempts to improve electrode selectivity have included manipulating the number and configuration of electrodes that are stimulated at any one time, displacing perilymph from the cochlea to restrict current flow along the cochlea, and reducing the distance between electrodes and neurons. One experimental approach by which the distance between neurons and electrodes may be reduced is to use neurotrophic factors to promote the regeneration of the peripheral dendrites of auditory neurons and guide them towards intracochlear electrodes. The likely requirements of a system for regenerating auditory neurons towards the cochlear electrode include either a stable release of neurotrophin, or transient neurotrophin followed by electrical stimulation; a close proximity of electrode to osseous spiral lamina or a polymer to bridge the gap between the two; guidance signals to attract neurons towards the electrode; patterning of the electrode surface to direct dendrites to electrode contacts and a 'stop' signal to arrest regeneration once the electrode has been reached.

Can transcranial electrical stimulation improve learning difficulties in atypical brain development? A future possibility for cognitive training.

PubMed

Krause, Beatrix; Cohen Kadosh, Roi

2013-10-01

Learning difficulties in atypical brain development represent serious obstacles to an individual's future achievements and can have broad societal consequences. Cognitive training can improve learning impairments only to a certain degree. Recent evidence from normal and clinical adult populations suggests that transcranial electrical stimulation (TES), a portable, painless, inexpensive, and relatively safe neuroenhancement tool, applied in conjunction with cognitive training can enhance cognitive intervention outcomes. This includes, for instance, numerical processing, language skills and response inhibition deficits commonly associated with profound learning difficulties and attention-deficit hyperactivity disorder (ADHD). The current review introduces the functional principles, current applications and promising results, and potential pitfalls of TES. Unfortunately, research in child populations is limited at present. We suggest that TES has considerable promise as a tool for increasing neuroplasticity in atypically developing children and may be an effective adjunct to cognitive training in clinical settings if it proves safe. The efficacy and both short- and long-term effects of TES on the developing brain need to be critically assessed before it can be recommended for clinical settings. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Induction of Fear by Intraoperative Stimulation During Awake Craniotomy: Case Presentation and Systematic Review of the Literature.

PubMed

Nowacki, Andreas; Seidel, Kathleen; Schucht, Philippe; Schindler, Kaspar; Abela, Eugenio; Heinemann, Dorothea; Gutbrod, Klemens; Wiest, Roland; Raabe, Andreas; Pollo, Claudio

2015-08-01

A case is presented and a systematic review of the literature is provided to update our current knowledge of induction of fear by cortical stimulation. We present a case of refractory epilepsy associated with a lesion where fear could be induced by intraoperative electrical stimulation of the posterior inner part of the superior temporal gyrus. We performed a systematic review of the literature using PubMed with the key words "epilepsy AND emotion", "cortical stimulation AND emotion," and "human brain stimulation AND behavior". Intraoperative cortical stimulation of the inner part of the posterior superior temporal gyrus reliably induced fear and progressive screaming behavior. Stimulation through subdural grid electrodes did not induce this phenomenon. A systematic review of the literature identified fear induction by stimulation of different widespread cortical areas including the temporal pole, the insula, and the anterior cingulate cortex. The posterior part of the superior temporal gyrus has so far not been associated with fear induction after electrical stimulation. Although our observation suggests that this area of the brain could be part of a network involved in the elicitation of fear, dysfunction of this network induced by epilepsy could also explain the observed phenomenon. Electrophysiologic and imaging studies must be conducted to improve our understanding of the cortical networks forming the neuroanatomical substrate of higher brain functions and experiences such as fear. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

How do stimulant treatments for ADHD work? Evidence for mediation by improved cognition.

PubMed

Hawk, Larry W; Fosco, Whitney D; Colder, Craig R; Waxmonsky, James G; Pelham, William E; Rosch, Keri S

2018-05-07

Stimulant medications such as methylphenidate (MPH) are the frontline treatment for Attention-Deficit/Hyperactivity Disorder (ADHD). Despite their well-documented efficacy, the mechanisms by which stimulants improve clinical outcomes are not clear. The current study evaluated whether MPH effects on classroom behavior were mediated by improved cognitive functioning. Children with ADHD (n = 82; 9-12 years old) participated in a week-long summer research camp, consisting of cognitive testing, classroom periods, and recreational activities. After a baseline day, participants completed a 3-day randomized, double-blind, placebo-controlled trial of MPH (at doses approximating 0.3 and 0.6 mg/kg of immediate-release MPH dosed TID). Cognitive domains included inhibitory control (Stop Signal Task and prepulse inhibition of startle), attention (Continuous Performance Task and reaction time variability), and working memory (forward and backward spatial span). Clinical outcomes included math seatwork productivity and teacher-rated classroom behavior. A within-subjects path-analytic approach was used to test mediation. MPH-placebo and dose-response contrasts were used to evaluate drug effects. Methylphenidate improved seatwork productivity and teacher ratings (ds = 1.4 and 1.1) and all domains of cognition (ds = 0.3-1.1). Inhibitory control (Stop Signal Task, SST) and working memory backward uniquely mediated the effect of MPH (vs. placebo) on productivity. Only working memory backward mediated the impact of MPH on teacher-rated behavior. The dose-response (0.6 vs. 0.3 mg/kg) effects were more modest for clinical outcomes (ds = 0.4 and 0.2) and cognition (ds = 0-0.3); there was no evidence of cognitive mediation of the clinical dose-response effects. These findings are novel in demonstrating that specific cognitive processes mediate clinical improvement with stimulant treatment for ADHD. They converge with work on ADHD theory, neurobiology, and treatment development in suggesting that inhibitory control and working memory may be mechanisms of stimulant treatment response in ADHD. More work is necessary to evaluate the degree to which these findings generalize to chronic treatment, a broader array of clinical outcomes, and nonstimulant treatments. © 2018 Association for Child and Adolescent Mental Health.

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.

Clinical improvement in patients with borderline personality disorder after treatment with repetitive transcranial magnetic stimulation: preliminary results.

PubMed

Reyes-López, Julian; Ricardo-Garcell, Josefina; Armas-Castañeda, Gabriela; García-Anaya, María; Arango-De Montis, Iván; González-Olvera, Jorge J; Pellicer, Francisco

2018-01-01

Current treatment of borderline personality disorder (BPD) consists of psychotherapy and pharmacological interventions. However, the use of repetitive transcranial magnetic stimulation (rTMS) could be beneficial to improve some BPD symptoms. The objective of this study was to evaluate clinical improvement in patients with BPD after application of rTMS over the right or left dorsolateral prefrontal cortex (DLPFC). Twenty-nine patients with BPD from the National Institute of Psychiatry, Mexico, were randomized in two groups to receive 15 sessions of rTMS applied over the right (1 Hz, n=15) or left (5 Hz, n=14) DLPFC. Improvement was measured by the Clinical Global Impression Scale for BPD (CGI-BPD), Borderline Evaluation of Severity Over Time (BEST), Beck Depression Inventory (BDI), Hamilton Anxiety Rating Scale (HAM-A), and Barratt Impulsiveness Scale (BIS). Intragroup comparison showed significant (p < 0.05) reductions in every psychopathologic domain of the CGI-BPD and in the total scores of all scales in both groups. Both protocols produced global improvement in severity and symptoms of BPD, particularly in impulsiveness, affective instability, and anger. Further studies are warranted to explore the therapeutic effect of rTMS in BPD. NCT02273674

Neurorehabilitation with new functional electrical stimulation for hemiparetic upper extremity in stroke patients.

PubMed

Hara, Yukihiro

2008-02-01

In recent years, our understanding of motor learning, neuroplasticity, and functional recovery after the occurrence of brain lesion has grown significantly. New findings in basic neuroscience have stimulated research in motor rehabilitation. Repeated motor practice and motor activity in a real-world environment have been identified in several prospective studies as favorable for motor recovery in stroke patients. Electrical stimulation can be applied in a variety of ways to the hemiparetic upper extremity following stroke. In this paper, an overview of current research into clinical and therapeutic applications of functional electrical stimulation (FES) is presented. In particular, electromyography (EMG)-initiated electrical muscle stimulation--but not electrical muscle stimulation alone--improves the motor function of the hemiparetic arm and hand. Triggered electrical stimulation is reported to be more effective than untriggered electrical stimulation in facilitating upper extremity motor recovery following stroke. Power-assisted FES induces greater muscle contraction by electrical stimulation in proportion to the voluntary integrated EMG signal picked up, which is regulated by a closed-loop control system. Power-assisted FES and motor point block for antagonist muscles have been applied with good results as a new hybrid FES therapy in an outpatient rehabilitation clinic for patients with stroke. Furthermore, a daily home program therapy with power-assisted FES using new equipment has been able to effectively improve wrist and finger extension and shoulder flexion. Proprioceptive sensory feedback might play an important role in power-assisted FES therapy. Although many physiotherapeutic modalities have been established, conclusive proof of their benefit and physiological models of their effects on neuronal structures and processes are still missing. A multichannel near-infrared spectroscopy study to noninvasively and dynamically measure hemoglobin levels in the brain during functional activity has shown that cerebral blood flow in the sensory-motor cortex on the injured side is higher during a power-assisted FES session than during simple active movement or simple electrical stimulation. Nevertheless, evidence-based strategies for motor rehabilitation are more easily available, particularly for patients with hemiparesis.

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

Summary of: Regenerative endodontics.

PubMed

Clark, Stephen J

2014-03-01

Significant advances in our understanding of the biological processes involved in tooth development and repair at the cellular and molecular levels have underpinned the newly emerging area of regenerative endodontics. Development of treatment protocols based on exploiting the natural wound healing properties of the dental pulp and applying tissue engineering principles has allowed reporting of case series showing preservation of tissue vitality and apexogenesis. To review current case series reporting regenerative endodontics. Current treatment approaches tend to stimulate more reparative than regenerative responses in respect of the new tissue generated, which often does not closely resemble the physiological structure of dentine-pulp. However, despite these biological limitations, such techniques appear to offer significant promise for improved treatment outcomes. Improved biological outcomes will likely emerge from the many experimental studies being reported and will further contribute to improvements in clinical treatment protocols.

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.

Frequency-specific insight into short-term memory capacity.

PubMed

Feurra, Matteo; Galli, Giulia; Pavone, Enea Francesco; Rossi, Alessandro; Rossi, Simone

2016-07-01

The digit span is one of the most widely used memory tests in clinical and experimental neuropsychology for reliably measuring short-term memory capacity. In the forward version, sequences of digits of increasing length have to be reproduced in the order in which they are presented, whereas in the backward version items must be reproduced in the reversed order. Here, we assessed whether transcranial alternating current stimulation (tACS) increases the memory span for digits of young and midlife adults. Imperceptibly weak electrical currents in the alpha (10 Hz), beta (20 Hz), theta (5 Hz), and gamma (40 Hz) range, as well as a sham stimulation, were delivered over the left posterior parietal cortex, a cortical region thought to sustain maintenance processes in short-term memory through oscillatory brain activity in the beta range. We showed a frequency-specific effect of beta-tACS that robustly increased the forward memory span of young, but not middle-aged, healthy individuals. The effect correlated with age: the younger the subjects, the greater the benefit arising from parietal beta stimulation. Our results provide evidence of a short-term memory capacity improvement in young adults by online frequency-specific tACS application. Copyright © 2016 the American Physiological Society.

Transcranial oscillatory direct current stimulation during sleep improves declarative memory consolidation in children with attention-deficit/hyperactivity disorder to a level comparable to healthy controls.

PubMed

Prehn-Kristensen, Alexander; Munz, Manuel; Göder, Robert; Wilhelm, Ines; Korr, Katharina; Vahl, Wiebke; Wiesner, Christian D; Baving, Lioba

2014-01-01

Slow oscillations (<1 Hz) during slow wave sleep (SWS) promote the consolidation of declarative memory. Children with attention-deficit/hyperactivity disorder (ADHD) have been shown to display deficits in sleep-dependent consolidation of declarative memory supposedly due to dysfunctional slow brain rhythms during SWS. Using transcranial oscillating direct current stimulation (toDCS) at 0.75 Hz, we investigated whether an externally triggered increase in slow oscillations during early SWS elevates memory performance in children with ADHD. 12 children with ADHD underwent a toDCS and a sham condition in a double-blind crossover study design conducted in a sleep laboratory. Memory was tested using a 2D object-location task. In addition, 12 healthy children performed the same memory task in their home environment. Stimulation enhanced slow oscillation power in children with ADHD and boosted memory performance to the same level as in healthy children. These data indicate that increasing slow oscillation power during sleep by toDCS can alleviate declarative memory deficits in children with ADHD. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

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

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

Improvements to the internal and external antenna H(-) ion sources at the Spallation Neutron Source.

PubMed

Welton, R F; Dudnikov, V G; Han, B X; Murray, S N; Pennisi, T R; Pillar, C; Santana, M; Stockli, M P; Turvey, M W

2014-02-01

The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30-40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ∼55 mA of H(-) beam current (∼1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H(-) yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

Ethics of the electrified mind: Defining issues and perspectives on the principled use of brain stimulation in medical research and clinical care

PubMed Central

Cabrera, Laura Y.; Evans, Emily L.; Hamilton, Roy H.

2013-01-01

In recent years, non-pharmacologic approaches to modifying human neural activity have gained increasing attention. One of these approaches is brain stimulation, which involves either the direct application of electrical current to structures in the nervous system or the indirect application of current by means of electromagnetic induction. Interventions that manipulate the brain have generally been regarded as having both the potential to alleviate devastating brain-related conditions and the capacity to create unforeseen and unwanted consequences. Hence, although brain stimulation techniques offer considerable benefits to society, they also raise a number of ethical concerns. In this paper we will address various dilemmas related to brain stimulation in the context of clinical practice and biomedical research. We will survey current work involving deep brain stimulation (DBS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We will reflect upon relevant similarities and differences between them, and consider some potentially problematic issues that may arise within the framework of established principles of medical ethics: nonmaleficence and beneficence, autonomy, and justice. PMID:23733209

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 changes in current densities and distribution.

Evaluation of focused multipolar stimulation for cochlear implants in long-term deafened cats

NASA Astrophysics Data System (ADS)

George, Shefin S.; Wise, Andrew K.; Fallon, James B.; Shepherd, Robert K.

2015-06-01

Objective. Focused multipolar (FMP) stimulation has been shown to produce restricted neural activation using intracochlear stimulation in animals with a normal population of spiral ganglion neurons (SGNs). However, in a clinical setting, the widespread loss of SGNs and peripheral fibres following deafness is expected to influence the effectiveness of FMP. Approach. We compared the efficacy of FMP stimulation to both monopolar (MP) and tripolar (TP) stimulation in long-term deafened cat cochleae (n = 8). Unlike our previous study, these cochleae contained <10% of the normal SGN population adjacent to the electrode array. We also evaluated the effect of electrode position on stimulation modes by using either modiolar facing or lateral wall facing half-band electrodes. The spread of neural activity across the inferior colliculus, a major nucleus within the central auditory pathway, was used as a measure of spatial selectivity. Main results. In cochleae with significant SGN degeneration, we observed that FMP and TP stimulation resulted in greater spatial selectivity than MP stimulation (p < 0.001). However, thresholds were significantly higher for FMP and TP stimulation compared to MP stimulation (p < 0.001). No difference between FMP and TP stimulation was found in any measures. The high threshold levels for FMP stimulation was significantly reduced without compromising spatial selectivity by varying the degree of current focusing (referred as ‘partial-FMP’ stimulation). Spatial selectivity of all stimulation modes was unaffected by the electrode position. Finally, spatial selectivity in long-term deafened cochleae was significantly less than that of cochleae with normal SGN population (George S S et al 2014 J. Neural Eng. 11 065003). Significance. The present results indicate that the greater spatial selectivity of FMP and TP stimulation over MP stimulation is maintained in cochleae with significant neural degeneration and is not adversely affected by electrode position. The greater spatial selectivity of FMP and TP stimulation would be expected to result in improved clinical performance.

Sustainability in medicine.

PubMed

George, Ruth; Coffin, Janis; George, Sierra

2013-01-01

Given the current state of the U.S. healthcare system, with increasingly complicated regulations and paperwork and decreasing reimbursements, the question arises: Is it possible to provide safe, high-quality healthcare and reduce costs? Furthermore, is it possible to care for the health of your patients while simultaneously caring for the financial health of your practice and promoting improvement in the overall health of the planet? This article will review some steps currently being taken by various companies and hopefully stimulate ideas for changes you may want to consider for your own practice, hospital, or institution.

Optimal design of neural stimulation current waveforms.

PubMed

Halpern, Mark

2009-01-01

This paper contains results on the design of electrical signals for delivering charge through electrodes to achieve neural stimulation. A generalization of the usual constant current stimulation phase to a stepped current waveform is presented. The electrode current design is then formulated as the calculation of the current step sizes to minimize the peak electrode voltage while delivering a specified charge in a given number of time steps. This design problem can be formulated as a finite linear program, or alternatively by using techniques for discrete-time linear system design.

Promoting Sleep Oscillations and Their Functional Coupling by Transcranial Stimulation Enhances Memory Consolidation in Mild Cognitive Impairment.

PubMed

Ladenbauer, Julia; Ladenbauer, Josef; Külzow, Nadine; de Boor, Rebecca; Avramova, Elena; Grittner, Ulrike; Flöel, Agnes

2017-07-26

Alzheimer's disease (AD) not only involves loss of memory functions, but also prominent deterioration of sleep physiology, which is already evident at the stage of mild cognitive impairment (MCI). Cortical slow oscillations (SO; 0.5-1 Hz) and thalamocortical spindle activity (12-15 Hz) during sleep, and their temporal coordination, are considered critical for memory formation. We investigated the potential of slow oscillatory transcranial direct current stimulation (so-tDCS), applied during a daytime nap in a sleep-state-dependent manner, to modulate these activity patterns and sleep-related memory consolidation in nine male and seven female human patients with MCI. Stimulation significantly increased overall SO and spindle power, amplified spindle power during SO up-phases, and led to stronger synchronization between SO and spindle power fluctuations in EEG recordings. Moreover, visual declarative memory was improved by so-tDCS compared with sham stimulation and was associated with stronger synchronization. These findings indicate a well-tolerated therapeutic approach for disordered sleep physiology and memory deficits in MCI patients and advance our understanding of offline memory consolidation. SIGNIFICANCE STATEMENT In the light of increasing evidence that sleep disruption is crucially involved in the progression of Alzheimer's disease (AD), sleep appears as a promising treatment target in this pathology, particularly to counteract memory decline. This study demonstrates the potential of a noninvasive brain stimulation method during sleep in patients with mild cognitive impairment (MCI), a precursor of AD, and advances our understanding of its mechanism. We provide first time evidence that slow oscillatory transcranial stimulation amplifies the functional cross-frequency coupling between memory-relevant brain oscillations and improves visual memory consolidation in patients with MCI. Copyright © 2017 the authors 0270-6474/17/377111-14$15.00/0.

Cumulative effects of anodal and priming cathodal tDCS on pegboard test performance and motor cortical excitability.

PubMed

Christova, Monica; Rafolt, Dietmar; Gallasch, Eugen

2015-01-01

Transcranial direct current stimulation (tDCS) protocols applied over the primary motor cortex are associated with changes in motor performance. This transcranial magnetic stimulation (TMS) study examines whether cathodal tDCS prior to motor training, combined with anodal tDCS during motor training improves motor performance and off-line learning. Three study groups (n=36) were trained on the grooved pegboard test (GPT) in a randomized, between-subjects design: SHAM-sham stimulation prior and during training, STIM1-sham stimulation prior and atDCS during training, STIM2-ctDCS stimulation prior and atDCS during training. Motor performance was assessed by GPT completion time and retested 14 days later to determine off-line learning. Cortical excitability was assessed via TMS at baseline (T0), prior training (T1), after training (T2), and 60 min after training (T3). Motor evoked potentials (MEP) were recorded from m. abductor pollicis brevis of the active left hand. GPT completion time was reduced for both stimulated groups compared to SHAM. For STIM2 this reduction in time was significantly higher than for STIM1 and further off-line learning occurred after STIM2. After ctDCS at T1, MEP amplitude and intracortical facilitation was decreased and intracortical inhibition was increased. After atDCS at T2, an opposite effect was observed for STIM1 and STIM2. For STIM2 these neuromodulatory effects were retained until T3. It is concluded that application of atDCS during the training improves pegboard performance and that additional priming with ctDCS has a positive effect on off-line learning. These cumulative behavioral gains were indicated by the preceding neuromodulatory changes. Copyright © 2015 Elsevier B.V. All rights reserved.

Neurostimulation for the treatment of axial back pain: a review of mechanisms, techniques, outcomes, and future advances.

PubMed

Deer, Timothy; Pope, Jason; Hayek, Salim; Narouze, Samer; Patil, Parag; Foreman, Robert; Sharan, Ashwini; Levy, Robert

2014-10-01

The use of spinal cord stimulation (SCS) is well established in the treatment of neuropathic pain. This procedure has been approved in the United States for neuropathic pain of the trunk and limbs from various conditions. International use is variable based on governmental policy. Most studies showing efficacy have focused on pain primarily in the limbs for such conditions as complex regional pain syndrome (CRPS), sciatica, radiculitis, ischemic limb pain, and peripheral neuropathy. Data on success in neuropathic pain of the trunk and particularly of the axial back are limited. New understanding about the targets of neuromodulation and their treatment with novel neurostimulation approaches has led to a new dawn of enthusiasm for spinal cord stimulation for axial low back pain. The authors review mechanisms, current and future targets, techniques, and their outcomes for treating axial back pain with neurostimulation. The paper discusses many newer methods and targets that may substantially improve results for the treatment of this patient group. The continuing evolution of technology and new data may well change these recommendations over time and regular updates of this manuscript will be critical moving forward. Improved technology and a better understanding of the goals of stimulation have led to a new ability to stimulate the axial low back and increase the effectiveness of these therapies to reduce pain. New paddle lead constructs, percutaneous paddle lead introduction, and other new technologies have led to an increased number of potential candidates for spinal cord stimulation. Optimizing the application of neurostimulation for chronic axial back pain will depend upon answering questions relating to patient selection, implantation technique, and stimulation parameters. © 2014 International Neuromodulation Society.

Hyper-Transcranial Alternating Current Stimulation: Experimental Manipulation of Inter-Brain Synchrony

PubMed Central

Szymanski, Caroline; Müller, Viktor; Brick, Timothy R.; von Oertzen, Timo; Lindenberger, Ulman

2017-01-01

We walk together, we watch together, we win together: Interpersonally coordinated actions are omnipresent in everyday life, yet the associated neural mechanisms are not well understood. Available evidence suggests that the synchronization of oscillatory activity across brains may provide a mechanism for the temporal alignment of actions between two or more individuals. In an attempt to provide a direct test of this hypothesis, we applied transcranial alternating current stimulation simultaneously to two individuals (hyper-tACS) who were asked to drum in synchrony at a set pace. Thirty-eight female-female dyads performed the dyadic drumming in the course of 3 weeks under three different hyper-tACS stimulation conditions: same-phase-same-frequency; different-phase-different-frequency; sham. Based on available evidence and theoretical considerations, stimulation was applied over right frontal and parietal sites in the theta frequency range. We predicted that same-phase-same-frequency stimulation would improve interpersonal action coordination, expressed as the degree of synchrony in dyadic drumming, relative to the other two conditions. Contrary to expectations, both the same-phase-same-frequency and the different-phase-different-frequency conditions were associated with greater dyadic drumming asynchrony relative to the sham condition. No influence of hyper-tACS on behavioral performance was seen when participants were asked to drum separately in synchrony to a metronome. Individual and dyad preferred drumming tempo was also unaffected by hyper-tACS. We discuss limitations of the present version of the hyper-tACS paradigm, and suggest avenues for future research. PMID:29167638

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.

Is high-frequency neuromuscular electrical stimulation a suitable tool for muscle performance improvement in both healthy humans and athletes?

PubMed

Gondin, Julien; Cozzone, Patrick J; Bendahan, David

2011-10-01

We aimed at providing an overview of the currently acknowledged benefits and limitations of neuromuscular electrical stimulation (NMES) training programs in both healthy individuals and in recreational and competitive athletes regarding muscle performance. Typical NMES resistance exercises are performed under isometric conditions and involve the application of electrical stimuli delivered as intermittent high frequencies trains (>40-50 Hz) through surface electrodes. NMES has been acknowledged as an efficient modality leading to significant improvements in isometric maximal voluntary strength. However, the resulting changes in dynamic strength, motor performance skills and explosive movements (i.e., jump performance, sprint ability) are still ambiguous and could only be obtained when NMES is combined with voluntary dynamic exercise such as plyometrics. Additionally, the effects of NMES on muscle fatigability are still poorly understood and required further investigations. While NMES effectiveness could be partially related to several external adjustable factors such as training intensity, current characteristics (e.g., intensity, pulse duration…) or the design of training protocols (number of contractions per session, number of sessions per week…), anatomical specificities (e.g., morphological organization of the axonal branches within the muscle) appear as the main factor accounting for the differences in NMES response. Overall, NMES cannot be considered as a surrogate training method, but rather as an adjunct to voluntary resistance training. The combination of these two training modalities should optimally improve muscle function.

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.

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.

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.

Modulating inhibitory control with direct current stimulation of the superior medial frontal cortex.

PubMed

Hsu, Tzu-Yu; Tseng, Lin-Yuan; Yu, Jia-Xin; Kuo, Wen-Jui; Hung, Daisy L; Tzeng, Ovid J L; Walsh, Vincent; Muggleton, Neil G; Juan, Chi-Hung

2011-06-15

The executive control of voluntary action involves not only choosing from a range of possible actions but also the inhibition of responses as circumstances demand. Recent studies have demonstrated that many clinical populations, such as people with attention-deficit hyperactivity disorder, exhibit difficulties in inhibitory control. One prefrontal area that has been particularly associated with inhibitory control is the pre-supplementary motor area (Pre-SMA). Here we applied non-invasive transcranial direct current stimulation (tDCS) over Pre-SMA to test its role in this behavior. tDCS allows for current to be applied in two directions to selectively excite or suppress the neural activity of Pre-SMA. Our results showed that anodal tDCS improved efficiency of inhibitory control. Conversely, cathodal tDCS showed a tendency towards impaired inhibitory control. To our knowledge, this is the first demonstration of non-invasive intervention tDCS altering subjects' inhibitory control. These results further our understanding of the neural bases of inhibitory control and suggest a possible therapeutic intervention method for clinical populations. Copyright © 2011 Elsevier Inc. All rights reserved.

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.

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

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.

Modeling bipolar stimulation of cardiac tissue

NASA Astrophysics Data System (ADS)

Galappaththige, Suran K.; Gray, Richard A.; Roth, Bradley J.

2017-09-01

Unipolar stimulation of cardiac tissue is often used in the design of cardiac pacemakers because of the low current required to depolarize the surrounding tissue at rest. However, the advantages of unipolar over bipolar stimulation are not obvious at shorter coupling intervals when the tissue near the pacing electrode is relatively refractory. Therefore, this paper analyzes bipolar stimulation of cardiac tissue. The strength-interval relationship for bipolar stimulation is calculated using the bidomain model and a recently developed parsimonious ionic current model. The strength-interval curves obtained using different electrode separations and arrangements (electrodes placed parallel to the fibers versus perpendicular to the fibers) indicate that bipolar stimulation results in more complex activation patterns compared to unipolar stimulation. An unusually low threshold stimulus current is observed when the electrodes are close to each other (a separation of 1 mm) because of break excitation. Unlike for unipolar stimulation, anode make excitation is not present during bipolar stimulation, and an abrupt switch from anode break to cathode make excitation can cause dramatic changes in threshold with very small changes in the interval. These results could impact the design of implantable pacemakers and defibrillators.

Electrical Stimulation Improves Microbial Salinity Resistance and Organofluorine Removal in Bioelectrochemical Systems

PubMed Central

Feng, Huajun; Zhang, Xueqin; Guo, Kun; Vaiopoulou, Eleni; Shen, Dongsheng; Long, Yuyang; Yin, Jun

2015-01-01

Fed batch bioelectrochemical systems (BESs) based on electrical stimulation were used to treat p-fluoronitrobenzene (p-FNB) wastewater at high salinities. At a NaCl concentration of 40 g/liter, p-FNB was removed 100% in 96 h in the BES, whereas in the biotic control (BC) (absence of current), p-FNB removal was only 10%. By increasing NaCl concentrations from 0 g/liter to 40 g/liter, defluorination efficiency decreased around 40% in the BES, and in the BC it was completely ceased. p-FNB was mineralized by 30% in the BES and hardly in the BC. Microorganisms were able to store 3.8 and 0.7 times more K+ and Na+ intracellularly in the BES than in the BC. Following the same trend, the ratio of protein to soluble polysaccharide increased from 3.1 to 7.8 as the NaCl increased from 0 to 40 g/liter. Both trends raise speculation that an electrical stimulation drives microbial preference toward K+ and protein accumulation to tolerate salinity. These findings are in accordance with an enrichment of halophilic organisms in the BES. Halobacterium dominated in the BES by 56.8% at a NaCl concentration of 40 g/liter, while its abundance was found as low as 17.5% in the BC. These findings propose a new method of electrical stimulation to improve microbial salinity resistance. PMID:25819966

Potentials and limits to enhance cognitive functions in healthy and pathological aging by tDCS

PubMed Central

Prehn, Kristin; Flöel, Agnes

2015-01-01

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is increasingly used in research and clinical settings to enhance the effects of cognitive training. In our present review, we will first summarize studies using tDCS alone and in combination with cognitive training in older adults and patients with Alzheimer’s dementia (AD). We will also review one study (Meinzer et al., 2014c) that showed an improvement in cognitive performance during anodal tDCS over the left inferior frontal cortex in patients with mild cognitive impairment (MCI) which is regarded as a prodromal stage of AD. Although promising short-term results have been reported, evidence from randomized controlled trials (RCTs) with sufficient sample sizes is scarce. In addition, stimulation protocols (in terms of intensity, duration, and repetition of stimulation) that lead to sustained improvements in outcome measures relevant for daily life still remain to be established. Following, we will discuss modulating factors such as technical parameters as well as the question whether there are specific cognitive functions (e.g., learning, memory consolidation, executive control) which are more amenable to tDCS enhancement than others. Finally, we will highlight future directions and limitations in this field and emphasize the need to conduct RCTs to establish efficacy of interventions for activities of daily life for a given patient population. PMID:26441526

Potentials and limits to enhance cognitive functions in healthy and pathological aging by tDCS.

PubMed

Prehn, Kristin; Flöel, Agnes

2015-01-01

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is increasingly used in research and clinical settings to enhance the effects of cognitive training. In our present review, we will first summarize studies using tDCS alone and in combination with cognitive training in older adults and patients with Alzheimer's dementia (AD). We will also review one study (Meinzer et al., 2014c) that showed an improvement in cognitive performance during anodal tDCS over the left inferior frontal cortex in patients with mild cognitive impairment (MCI) which is regarded as a prodromal stage of AD. Although promising short-term results have been reported, evidence from randomized controlled trials (RCTs) with sufficient sample sizes is scarce. In addition, stimulation protocols (in terms of intensity, duration, and repetition of stimulation) that lead to sustained improvements in outcome measures relevant for daily life still remain to be established. Following, we will discuss modulating factors such as technical parameters as well as the question whether there are specific cognitive functions (e.g., learning, memory consolidation, executive control) which are more amenable to tDCS enhancement than others. Finally, we will highlight future directions and limitations in this field and emphasize the need to conduct RCTs to establish efficacy of interventions for activities of daily life for a given patient population.

“Effects of combined peripheral nerve stimulation and brain polarization on performance of a motor sequence task after chronic stroke”

PubMed Central

Celnik, Pablo; Paik, Nam-Jong; Vandermeeren, Yves; Dimyan, Michael; Cohen, Leonardo G.

2009-01-01

Background Recent work demonstrated that application of peripheral nerve and cortical stimulation independently can induce modest improvements in motor performance in patients with stroke. Objective To test the hypothesis that combining peripheral nerve stimulation (PNS) to the paretic hand with anodal direct current stimulation (tDCS) to the ipsilesional primary motor cortex (M1) would facilitate beneficial effects of motor training more than each intervention alone or sham (tDCSSham and PNSSham). Methods Nine chronic stroke patients completed a blinded, cross-over designed study. In separate sessions, we investigated the effects of single applications of PNS+tDCS, PNS+tDCSSham, tDCS+PNSSham and PNSSham+tDCSSham prior to motor training on the ability to perform finger motor sequences with the paretic hand. Results PNS+tDCS resulted in a 41.3% improvement in the number of correct key presses relative to PNSSham+tDCSSham, 15.4% relative to PNS+tDCSSham and 22.7% relative to tDCS+PNSSham. These performance differences were maintained 1 and 6 days after the end of the training. Conclusions These results indicate that combining PNS with tDCS can facilitate the beneficial effects of training on motor performance beyond levels reached with each intervention alone, a finding of relevance for the neurorehabilitation of motor impairments after stroke. PMID:19286579

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.

Targeting Lumbar Spinal Neural Circuitry by Epidural Stimulation to Restore Motor Function After Spinal Cord Injury.

PubMed

Minassian, Karen; McKay, W Barry; Binder, Heinrich; Hofstoetter, Ursula S

2016-04-01

Epidural spinal cord stimulation has a long history of application for improving motor control in spinal cord injury. This review focuses on its resurgence following the progress made in understanding the underlying neurophysiological mechanisms and on recent reports of its augmentative effects upon otherwise subfunctional volitional motor control. Early work revealed that the spinal circuitry involved in lower-limb motor control can be accessed by stimulating through electrodes placed epidurally over the posterior aspect of the lumbar spinal cord below a paralyzing injury. Current understanding is that such stimulation activates large-to-medium-diameter sensory fibers within the posterior roots. Those fibers then trans-synaptically activate various spinal reflex circuits and plurisegmentally organized interneuronal networks that control more complex contraction and relaxation patterns involving multiple muscles. The induced change in responsiveness of this spinal motor circuitry to any residual supraspinal input via clinically silent translesional neural connections that have survived the injury may be a likely explanation for rudimentary volitional control enabled by epidural stimulation in otherwise paralyzed muscles. Technological developments that allow dynamic control of stimulation parameters and the potential for activity-dependent beneficial plasticity may further unveil the remarkable capacity of spinal motor processing that remains even after severe spinal cord injuries.

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.