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Crowley SJ, Iordan AD, Rinna K, Barmada S, Hampstead BM. Comparing high definition transcranial direct current stimulation to left temporoparietal junction and left inferior frontal gyrus for logopenic primary progressive aphasia: A single-case study. Neuropsychol Rehabil 2024:1-26. [PMID: 38358112 DOI: 10.1080/09602011.2024.2314878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 11/18/2023] [Indexed: 02/16/2024]
Abstract
Logopenic variant primary progressive aphasia (lvPPA) is characterized by word-finding deficits and phonologic errors in fluent speech. Transcranial direct current stimulation (tDCS) targeting either left temporoparietal junction (TPJ) or left inferior frontal gyrus (IFG) show evidence of improving language function in lvPPA. The present case study evaluated the effects of two separate rounds of high definition tDCS (HD-tDCS) (4 mA; 30 sessions) on language and functional neuroimaging in a 57-year-old woman with lvPPA. Stimulation was centred on two different regions across rounds: (1) left TPJ, and (2) left (IFG). Results showed an improved proportion of content to floorholder words during a naturalistic speech task through both rounds as well as change in confrontation naming after TPJ (improvement) and IFG (worsened) stimulation. fMRI connectivity during task showed left lateralized positive correlations following round 1 and anti-correlations with components of the default mode network following round 2. Resting state segregation of a language-associated functional network increased following both rounds, and task-based segregation of the same network increased following IFG stimulation. These results suggest that stimulation to both regions using HD-tDCS may improve language function in lvPPA, while simultaneously eliciting widespread changes beyond the targeted area in neuronal activity and functional connectivity.
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Affiliation(s)
- Samuel J Crowley
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan Medicine, Ann Arbor, MI, USA
- Mental Health Service, Veteran Affairs Ann Arbor Healthcare System, Ann Arbor, MI, USA
| | - Alexandru D Iordan
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan Medicine, Ann Arbor, MI, USA
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA
| | - Kayla Rinna
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan Medicine, Ann Arbor, MI, USA
- Department of Psychology, Eastern Michigan University, Ypsilanti, MI, USA
| | - Sami Barmada
- Department of Neurology, University of Michigan Medicine, Ann Arbor, MI, USA
| | - Benjamin M Hampstead
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan Medicine, Ann Arbor, MI, USA
- Mental Health Service, Veteran Affairs Ann Arbor Healthcare System, Ann Arbor, MI, USA
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El Jamal C, Harrie A, Rahman-Filipiak A, Iordan AD, DaSilva AF, Ploutz-Snyder R, Khadr L, Vesia M, Bikson M, Hampstead BM. Tolerability and blinding of high-definition transcranial direct current stimulation among older adults at intensities of up to 4 mA per electrode. Brain Stimul 2023; 16:1328-1335. [PMID: 37660936 DOI: 10.1016/j.brs.2023.08.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 09/05/2023] Open
Abstract
BACKGROUND Few studies have investigated tolerability, blinding, and double-blinding of High-Definition transcranial Direct Current Stimulation (HD-tDCS) at amplitudes above 2 milliamps (mA). OBJECTIVE We examined a) tolerability of HD-tDCS during stimulation sessions and b) blinding and double blinding of participants and study team members. METHODS Data from a mixed neurologic sample of 292 older adults were pooled from 3046 HD-tDCS sessions (2329 active; 717 sham). Per electrode amplitudes ranged from 1 mA to 4 mA with total currents up to 10 mA. Participants completed a standardized sensation (tolerability) questionnaire after each session. Participants and study team members stated whether the participant received active or sham stimulation at the end of various sessions. Data were collapsed into the presence/absence of a symptom due to low rates of positive responding and were analyzed for both differences and bioequivalency. RESULTS There were no safety-related adverse events. HD-tDCS was well tolerated with mostly no ("none") or "mild" sensations reported across sessions, regardless of active or sham condition and in both stimulation naïve and experienced participants. There were no significant differences in side effects between active and sham, with some achieving bioequivalence. Tingling and itching were significantly more common after lower (<2 mA) than higher (≥3 mA) amplitude active sessions, while skin redness was significantly more common after higher amplitudes. Blinding was effective at the participant and study team levels. CONCLUSIONS HD-tDCS was well tolerated with center electrode amplitudes up to 4 mA. The bimodal ramp-up/down format of the sham was effective for blinding. These results support higher scalp-based amplitudes that enable greater brain-based current intensities in older adults.
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Affiliation(s)
- Carine El Jamal
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Ashley Harrie
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Annalise Rahman-Filipiak
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Alexandru D Iordan
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Alexandre F DaSilva
- Headache & Orofacial Pain Effort (H.O.P.E.), Biologic & Materials Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Robert Ploutz-Snyder
- Applied Biostatistics Laboratory, School of Nursing, University of Michigan, Ann Arbor, MI, USA
| | - Lara Khadr
- Applied Biostatistics Laboratory, School of Nursing, University of Michigan, Ann Arbor, MI, USA
| | - Michael Vesia
- Brain Behavior Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Benjamin M Hampstead
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA; Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Schmidt N, Menéndez-Granda M, Münger R, Reber TP, Bayen UJ, Gümüsdagli FE, Hering A, Joly-Burra E, Kliegel M, Peter J. Modulating prospective memory and attentional control with high-definition transcranial current stimulation: Study protocol of a randomized, double-blind, and sham-controlled trial in healthy older adults. PLoS One 2023; 18:e0289532. [PMID: 37549139 PMCID: PMC10406223 DOI: 10.1371/journal.pone.0289532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 07/12/2023] [Indexed: 08/09/2023] Open
Abstract
The ability to remember future intentions (i.e., prospective memory) is influenced by attentional control. At the neuronal level, frontal and parietal brain regions have been related to attentional control and prospective memory. It is debated, however, whether more or less activity in these regions is beneficial for older adults' performance. We will test that by systematically enhancing or inhibiting activity in these regions with anodal or cathodal high-definition transcranial direct current stimulation in older adults. We will include n = 105 healthy older volunteers (60-75 years of age) in a randomized, double-blind, sham-controlled, and parallel-group design. The participants will receive either cathodal, anodal, or sham high-definition transcranial direct current stimulation of the left or right inferior frontal gyrus, or the right superior parietal gyrus (1mA for 20 min). During and after stimulation, the participants will complete tasks of attentional control and prospective memory. The results of this study will clarify how frontal and parietal brain regions contribute to attentional control and prospective memory in older healthy adults. In addition, we will elucidate the relationship between attentional control and prospective memory in that age group. The study has been registered with ClinicalTrials.gov on the 12th of May 2021 (trial identifier: NCT04882527).
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Affiliation(s)
- Nadine Schmidt
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
- Graduate School for Health Sciences, University of Bern, Bern, Switzerland
| | - Marta Menéndez-Granda
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
- Graduate School for Health Sciences, University of Bern, Bern, Switzerland
| | - Ronya Münger
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
| | - Thomas P. Reber
- Faculty of Psychology, Uni Distance Suisse, Brig, Switzerland
| | - Ute J. Bayen
- Institute for Experimental Psychology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Fabian E. Gümüsdagli
- Institute for Experimental Psychology, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Alexandra Hering
- Department of Developmental Psychology, Tilburg School for Social and Behavioural Sciences, Tilburg University, Tilburg, The Netherlands
| | - Emilie Joly-Burra
- Cognitive Aging Lab (CAL), Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland
- Centre for the Interdisciplinary Study of Gerontology and Vulnerability, University of Geneva, Geneva, Switzerland
- Swiss Centre of Expertise in Life Course Research, LIVES Centre, Lausanne and Geneva, Switzerland
| | - Matthias Kliegel
- Cognitive Aging Lab (CAL), Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland
- Centre for the Interdisciplinary Study of Gerontology and Vulnerability, University of Geneva, Geneva, Switzerland
- Swiss Centre of Expertise in Life Course Research, LIVES Centre, Lausanne and Geneva, Switzerland
| | - Jessica Peter
- University Hospital of Old Age Psychiatry and Psychotherapy, University of Bern, Bern, Switzerland
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Random Forest Classification to Predict Response to High-Definition Transcranial Direct Current Stimulation for Tinnitus Relief: A Preliminary Feasibility Study. Ear Hear 2022; 43:1816-1823. [PMID: 35666538 PMCID: PMC9592176 DOI: 10.1097/aud.0000000000001246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVES Transcranial direct current stimulation (tDCS) of the right dorsolateral prefrontal cortex has been hypothesized to reduce tinnitus severity by modifying cortical activity in brain regions associated with the perception of tinnitus. However, individual response to tDCS has proven to be variable. We investigated the feasibility of using random forest classification to predict the response to high-definition (HD) tDCS for tinnitus relief. DESIGN A retrospective analysis was performed on a dataset consisting of 99 patients with subjective tinnitus receiving six consecutive sessions of HD-tDCS at the Antwerp University Hospital. A baseline assessment consisted of pure-tone audiometry and a set of questionnaires including the Tinnitus Functional Index (TFI), Hospital Anxiety and Depression Scale, and Edinburgh Handedness Inventory. Random forest classification was applied to predict, based on baseline questionnaire scores and hearing levels, whether each individual responded positively to the treatment (defined as a decrease of at least 13 points on the TFI). Further testing of the model was performed on an independent cohort of 32 patients obtained from the tinnitus center at the University of Regensburg. RESULTS Twenty-four participants responded positively to the HD-tDCS treatment. The random forest classifier predicted treatment response with an accuracy of 85.71% (100% sensitivity, 81.48% specificity), significantly outperforming a more traditional logistic regression approach. Performance of the classifier on an independent cohort was slightly but not significantly above chance level (71.88% accuracy, 66.67% sensitivity, 73.08% specificity). Feature importance analyses revealed that baseline tinnitus severity, co-occurrence of depressive symptoms and handedness were the most important predictors of treatment response. Baseline TFI scores were significantly higher in responders than in nonresponders. CONCLUSIONS The proposed random forest classifier predicted treatment response with a high accuracy, significantly outperforming a more traditional statistical approach. Machine learning methods to predict treatment response might ultimately be used in a clinical setting to guide targeted treatment recommendations for individual tinnitus patients.
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Andrade SM, Cecília de Araújo Silvestre M, Tenório de França EÉ, Bezerra Sales Queiroz MH, de Jesus Santana K, Lima Holmes Madruga ML, Torres Teixeira Mendes CK, Araújo de Oliveira E, Bezerra JF, Barreto RG, Alves Fernandes da Silva SM, Alves de Sousa T, Medeiros de Sousa WC, Patrícia da Silva M, Cintra Ribeiro VM, Lucena P, Beltrammi D, Catharino RR, Caparelli-Dáquer E, Hampstead BM, Datta A, Teixeira AL, Fernández-Calvo B, Sato JR, Bikson M. Efficacy and safety of HD-tDCS and respiratory rehabilitation for critically ill patients with COVID-19 The HD-RECOVERY randomized clinical trial. Brain Stimul 2022; 15:780-788. [PMID: 35568312 PMCID: PMC9093082 DOI: 10.1016/j.brs.2022.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 04/19/2022] [Accepted: 05/05/2022] [Indexed: 11/28/2022] Open
Abstract
Background and purpose Acute Respiratory Distress Syndrome (ADRS) due to coronavirus disease 2019 (COVID-19) has been associated with muscle fatigue, corticospinal pathways dysfunction, and mortality. High-Definition transcranial Direct Current Stimulation (HD-tDCS) may be used to attenuate clinical impairment in these patients. The HD-RECOVERY randomized clinical trial was conducted to evaluate the efficacy and safety of HD-tDCS with respiratory rehabilitation in patients with moderate to severe ARDS due to COVID-19. Methods Fifty-six critically ill patients were randomized 1:1 to active (n = 28) or sham (n = 28) HD-tDCS (twice a day, 30-min, 3-mA) plus respiratory rehabilitation for up to 10 days or until intensive care unit discharge. The primary outcome was ventilator-free days during the first 28 days, defined as the number of days free from mechanical ventilation. Furthermore, secondary outcomes such as delirium, organ failure, hospital length of stay and adverse effects were investigated. Results Active HD-tDCS induced more ventilator-free days compared to sham HD-tDCS. Patients in the active group vs in the sham group experienced lower organ dysfunction, delirium, and length of stay rates over time. In addition, positive clinical response was higher in the active vs sham group. There was no significant difference in the prespecified secondary outcomes at 5 days. Adverse events were similar between groups. Conclusions Among patients with COVID-19 and moderate to severe ARDS, use of active HD-tDCS compared with sham HD-tDCS plus respiratory rehabilitation resulted in a statistically significant increase in the number of ventilator-free days over 28 days. HD-tDCS combined with concurrent rehabilitation therapy is a safe, feasible, potentially add-on intervention, and further trials should examine HD-tDCS efficacy in a larger sample of patients with COVID-19 and severe hypoxemia.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Paulo Lucena
- Health Secretary, Government of Paraíba, João Pessoa, Brazil
| | | | - Rodrigo Ramos Catharino
- Thomson Mass Spectrometry Laboratory, Institute of Chemistry, State University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Egas Caparelli-Dáquer
- Nervous System Electric Stimulation Lab, Rio de Janeiro State University, Rio de Janeiro, Brazil
| | - Benjamin M Hampstead
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan & Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, Ann Arbor, United States
| | - Abhishek Datta
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, United States
| | - Antonio Lucio Teixeira
- Department of Psychiatry and Behavioral Sciences, McGovern Medical School, University of Texas Health Science Center, Houston, United States
| | - Bernardino Fernández-Calvo
- Department of Psychology, University of Cordoba, Cordoba, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital, University of Cordoba, Cordoba, Spain
| | - João Ricardo Sato
- Center of Mathematics, Computing and Cognition. Federal University of ABC, Santo André, Brazil
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York of CUNY, New York, United States
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Iordan AD, Ryan S, Tyszkowski T, Peltier SJ, Rahman-Filipiak A, Hampstead BM. High-definition transcranial direct current stimulation enhances network segregation during spatial navigation in mild cognitive impairment. Cereb Cortex 2022; 32:5230-5241. [PMID: 35134853 PMCID: PMC9667179 DOI: 10.1093/cercor/bhac010] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/08/2022] [Accepted: 01/09/2022] [Indexed: 02/06/2023] Open
Abstract
Spatial navigation is essential for everyday life and relies on complex network-level interactions. Recent evidence suggests that transcranial direct current stimulation (tDCS) can influence the activity of large-scale functional brain networks. We characterized brain-wide changes in functional network segregation (i.e. the balance of within vs. between-network connectivity strength) induced by high-definition (HD) tDCS in older adults with mild cognitive impairment (MCI) during virtual spatial navigation. Twenty patients with MCI and 22 cognitively intact older adults (healthy controls-HC) underwent functional magnetic resonance imaging following two counterbalanced HD-tDCS sessions (one active, one sham) that targeted the right parietal cortex (center anode at P2) and delivered 2 mA for 20 min. Compared to HC, MCI patients showed lower brain-wide network segregation following sham HD-tDCS. However, following active HD-tDCS, MCI patients' network segregation increased to levels similar to those in HC, suggesting functional normalization. Follow-up analyses indicated that the increase in network segregation for MCI patients was driven by HD-tDCS effects on the "high-level"/association brain networks, in particular the dorsal-attention and default-mode networks. HD-tDCS over the right parietal cortex may normalize the segregation/integration balance of association networks during spatial navigation in MCI patients, highlighting its potential to restore brain activity in Alzheimer's disease.
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Affiliation(s)
- Alexandru D Iordan
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA,Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA
| | - Shannon Ryan
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA
| | - Troy Tyszkowski
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA
| | - Scott J Peltier
- Functional MRI Laboratory, University of Michigan, Ann Arbor, MI 48109, USA,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Annalise Rahman-Filipiak
- Research Program on Cognition and Neuromodulation Based Interventions, Department of Psychiatry, University of Michigan, Ann Arbor, MI 48105, USA
| | - Benjamin M Hampstead
- Corresponding author: University of Michigan, 2101 Commonwealth Blvd Ste C, Ann Arbor, MI 48105, USA.
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Wan R, Wang Y, Feng B, Jiang X, Xu Y, Zhang Z, Liu Y, Wang Y. Effect of High-definition Transcranial Direct Current Stimulation on Conditioned Pain Modulation in Healthy Adults: A Crossover Randomized Controlled Trial. Neuroscience 2021; 479:60-69. [PMID: 34710538 DOI: 10.1016/j.neuroscience.2021.10.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/16/2021] [Accepted: 10/18/2021] [Indexed: 01/07/2023]
Abstract
The disorder of the conditioned pain modulation (CPM) system is one of the main causes of pain perception in individuals. High-definition transcranial direct current stimulation (HD-tDCS) targeting specific brain areas was indicated to have an analgesic effect possibly by activating the endogenous pain inhibition pathway evident in CPM. However, discrepancies were found in previous limited studies of varied homogeneity and quality. Therefore, the present study applied 2 mA HD-tDCS (20 min) in the left primary motor cortex (M1) among 35 healthy adults with a blinded crossover study design, to investigate its effectiveness on optimizing the analgesic effect in healthy individuals through assessing changes of the CPM. The univariate and multivariate general linear models were used to evaluate the intervention effect between-group on the Δ-value (after-intervention minus before-intervention) during CPM (primary outcome), pressure pain threshold (PPT), and cold pressure threshold (CPT) (secondary outcome), respectively. A significant between-group difference in Δ-CPM was found for active stimulation. HD-tDCS significantly improved the analgesic efficiency of Δ-CPM, compared with the sham control, after adjusting the confounding factors including age, gender, psychological status, as well as the sequence effect. The changes of CPM were positively correlated with the total physical activity volume. In conclusion, our findings provide evidence support to the effectiveness of HD-tDCS on endogenous pain modulation among healthy adults. Further studies are required to explore the analgesic effect of tDCS among patients with chronic pain, thereby facilitating optimal chronic pain management.
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Affiliation(s)
- Ruihan Wan
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China; Department of Sport Rehabilitation, Shenyang Sport University, Shenyang, China
| | - Yafei Wang
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Beibei Feng
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China; Department of Orthopedics & Traumatology, The University of Hong Kong, Hong Kong Special Administrative Region
| | - Xue Jiang
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China; Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
| | - Yangfan Xu
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ziping Zhang
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ying Liu
- Department of Kinesiology, California State University, Northridge, United States
| | - Yuling Wang
- Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
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Lengu K, Ryan S, Peltier SJ, Tyszkowski T, Kairys A, Giordani B, Hampstead BM. Effects of High Definition-Transcranial Direct Current Stimulation on Local GABA and Glutamate Levels Among Older Adults with and without Mild Cognitive Impairment: An Exploratory Study. J Alzheimers Dis 2021; 84:1091-1102. [PMID: 34602464 DOI: 10.3233/jad-201091] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Prior research, primarily with young adults, suggests transcranial direct current stimulation (tDCS) effects are driven by the primary excitatory and/or inhibitory neurotransmitters, glutamate, and gamma-aminobutyric acid (GABA), respectively. OBJECTIVE We examined the neurometabolic mechanisms of tDCS in older adults with and without mild cognitive impairment (MCI). METHODS We used data from a double-blind, cross-over, randomized controlled trial (NCT01958437) in 32 older adults to evaluate high definition (HD)-tDCS-induced changes in glutamate and GABA via magnetic resonance spectroscopy (MRS). Participants underwent MRS following two counterbalanced HD-tDCS sessions (one active, one sham) that targeted the right superior parietal cortex (center anode at P2) and delivered 2mA for 20 minutes. RESULTS Relative to sham, and when co-varying for MRS voxel overlap and right superior parietal volume, active HD-tDCS significantly increased GABA and decreased the ratio of glutamate to GABA. No changes were observed in a left prefrontal control MRS voxel. Although we did not find a significant correlation between strength of delivered current (measured via MRI-based computational modeling) and neurometabolite change, there was a robust positive relationship between the volume of right superior parietal cortex and neurometabolite change. CONCLUSION Our preliminary findings of increased GABA and reduced glutamate/GABA ratio raise the possibility that (HD-)tDCS effects differ by age. Moreover, age- and disease-related regional brain volume loss may be especially important to consider when planning future studies. Replication would emphasize the importance of developing population-specific tDCS parameters that consider structural and physiologic changes associated with "normal" and pathological aging.
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Affiliation(s)
- Ketrin Lengu
- Neuropsychology Section, Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.,Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Shannon Ryan
- Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Scott J Peltier
- Functional MRI Laboratory, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Troy Tyszkowski
- Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Anson Kairys
- Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Bruno Giordani
- Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Benjamin M Hampstead
- Neuropsychology Section, Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.,Research Program on Cognition and Neuromodulation-Based Interventions (RP-CNBI), Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
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A Novel Highly Durable Carbon/Silver/Silver Chloride Composite Electrode for High-Definition Transcranial Direct Current Stimulation. NANOMATERIALS 2021; 11:nano11081962. [PMID: 34443793 PMCID: PMC8400871 DOI: 10.3390/nano11081962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/21/2021] [Accepted: 07/27/2021] [Indexed: 11/29/2022]
Abstract
High-definition transcranial direct current stimulation (HD-tDCS) is a promising non-invasive neuromodulation technique, which has been widely used in the clinical intervention and treatment of neurological or psychiatric disorders. Sintered Ag/AgCl electrode has become a preferred candidate for HD-tDCS, but its service life is very short, especially for long-term anodal stimulation. To address this issue, a novel highly durable conductive carbon/silver/silver chloride composite (C/Ag/AgCl) electrode was fabricated by a facile cold rolling method. The important parameters were systematically optimized, including the conductive enhancer, the particle size of Ag powder, the C:Ag:PTFE ratio, the saline concentration, and the active substance loading. The CNT/Ag/AgCl-721 electrode demonstrated excellent specific capacity and cycling performance. Both constant current anodal polarization and simulated tDCS measurement demonstrated that the service life of the CNT/Ag/AgCl-721 electrodes was 15-16 times of that of sintered Ag/AgCl electrodes. The much longer service life can be attributed to the formation of the three-dimensional interpenetrating conductive network with CNT doping, which can maintain a good conductivity and cycling performance even if excessive non-conductive AgCl is accumulated on the surface during long-term anodal stimulation. Considering their low cost, long service life, and good skin tolerance, the proposed CNT/Ag/AgCl electrodes have shown promising application prospects in HD-tDCS, especially for daily life scenarios.
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Solomons CD, Shanmugasundaram V. Transcranial direct current stimulation: A review of electrode characteristics and materials. Med Eng Phys 2020; 85:63-74. [PMID: 33081965 DOI: 10.1016/j.medengphy.2020.09.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/10/2020] [Accepted: 09/25/2020] [Indexed: 12/15/2022]
Abstract
Electrode characteristics are crucial in transcranial direct current stimulation (tDCS) since electrode design and placement determine the cortical area being modulated, current density and spatial resolution of stimulation. Early research on tDCS sought to determine optimal parameters for stimulation by specifying maximum current, duration and sizes of electrodes. Further research focused on determining efficient ways to deliver stimulation to targeted regions on the cortex with minimal discomfort to the user by altering electrode size, placement, shape and material. This review aims to give an insight on the main characteristics of electrodes used in tDCS and on the variability found in electrode parameters and placements from tDCS to high definition tDCS (HD-tDCS) applications and beyond.
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Affiliation(s)
- Cassandra D Solomons
- School of Electrical Engineering, Vellore Institute of Technology, Vellore 632014, India
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Hunold A, Ortega D, Schellhorn K, Haueisen J. Novel flexible cap for application of transcranial electrical stimulation: a usability study. Biomed Eng Online 2020; 19:50. [PMID: 32552720 PMCID: PMC7302393 DOI: 10.1186/s12938-020-00792-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 06/06/2020] [Indexed: 11/12/2022] Open
Abstract
Background Advances in transcranial electrical stimulation (tES) are hampered by the conventional rubber electrodes manually attached to the head with rubber bands. This procedure limits montages to a few electrodes, is error prone with respect to electrode configurations and is burdensome for participants and operators. A newly developed flexible cap with integrated textile stimulation electrodes was compared to the conventional setup of rubber electrodes inserted into sponges fixated by rubber bands, with respect to usability and reliability. Two operators applied both setups to 20 healthy volunteers participating in the study. Electrode position and impedance measures as well as subjective evaluations from participants and operators were obtained throughout the stimulation sessions. Results Our results demonstrated the superiority of the flexible cap by means of significantly higher electrode configuration reproducibility and a more efficient application. Both, operators and volunteers evaluated the flexible cap as easier to use and more comfortable to wear when compared to the conventional setup. Conclusion In conclusion, the new cap improves existing and opens new application scenarios for tES.
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Affiliation(s)
- Alexander Hunold
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.
| | - Daniela Ortega
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,Bioinstrumentation and Clinical Engineering Research Group, Universidad de Antioquia, Medellín, 050010, Colombia
| | | | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, 98693, Ilmenau, Germany.,Hans Berger Department of Neurology, Biomagnetic Center, University Hospital Jena, 07747, Jena, Germany
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