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Chuderski A, Chinta SR. Transcranial alternating current stimulation barely enhances working memory in healthy adults: A meta-analysis. Brain Res 2024; 1839:149022. [PMID: 38801916 DOI: 10.1016/j.brainres.2024.149022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024]
Abstract
Working memory (WM) is a pivotal neural mechanism for cognitive function and ability. Transcranial alternating current stimulation (tACS) was used to improve WM by entraining key brain rhythms. We submitted to meta-analysis 143 effects of tACS on WM performance, found in 42 reports published between 2014 and 2023, encompassing a total of 1386 healthy adults stimulated. The overall effect size of 134 interventions intended to improve WM equaled Hedges' g = 0.076 [0.039, 0.113]. However, after correcting for a significant publication bias this effect size dropped to zero. By contrast, 9 interventions distorting the brain synchronization using antiphase tACS reliably decreased WM performance, with Hedges' g = -0.266, [-0.458, -0.074]. Individuating the targeted frequency band was the only reliable moderator. The disparity between our null outcome and moderately positive tACS effects estimated by previous meta-analyses resulted from our inclusion of the most recent studies mostly reporting negligible effects. Our results suggest that current tACS protocols barely enhance WM in healthy adults. More research is needed to develop effective methods for WM stimulation.
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Kim J, Park S, Kim H, Roh D, Kim DH. Home-based, Remotely Supervised, 6-Week tDCS in Patients With Both MCI and Depression: A Randomized Double-Blind Placebo-Controlled Trial. Clin EEG Neurosci 2024; 55:531-542. [PMID: 38105601 DOI: 10.1177/15500594231215847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
As depressive symptom is considered a prodrome, a risk factor for progression from mild cognitive impairment (MCI) to dementia, improving depressive symptoms should be considered a clinical priority in patients with MCI undergoing transcranial direct current stimulation (tDCS) intervention. We aimed to comprehensively evaluate the efficacy of the home-based and remotely monitored tDCS in patients with both MCI and depression, by integrating cognitive, psychological, and electrophysiological indicators. In a 6-week, randomized, double blind, and sham-controlled study, 37 community-dwelling patients were randomly assigned to either an active or a sham stimulation group, and received 30 home-based sessions of 2 mA tDCS for 30 min with the anode located over the left and cathode over the right dorsolateral prefrontal cortex. We measured depressive symptoms, neurocognitive function, and resting-state electroencephalography. In terms of effects of both depressive symptoms and cognitive functions, active tDCS was not significantly different from sham tDCS. However, compared to sham stimulation, active tDCS decreased and increased the activation of delta and beta frequencies, respectively. Moreover, the increase in beta activity was correlated with the cognitive enhancement only in the active group. It was not possible to reach a definitive conclusion regarding the efficacy of tDCS on depression and cognition in patients with both MCI and depression. Nevertheless, the relationship between the changes of electrophysiology and cognitive performance suggests potential neuroplasticity enhancement implicated in cognitive processes by tDCS.
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Affiliation(s)
- Jiheon Kim
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
- *These first authors contributed equally to this work
| | - Seungchan Park
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
- *These first authors contributed equally to this work
| | - Hansol Kim
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Daeyoung Roh
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Do Hoon Kim
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
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Dehghani A, Bango C, Murphy EK, Halter RJ, Wager TD. Independent effects of transcranial direct current stimulation and social influence on pain. Pain 2024:00006396-990000000-00657. [PMID: 39167466 DOI: 10.1097/j.pain.0000000000003338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 05/28/2024] [Indexed: 08/23/2024]
Abstract
ABSTRACT Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulatory technique with the potential to provide pain relief. However, tDCS effects on pain are variable across existing studies, possibly related to differences in stimulation protocols and expectancy effects. We investigated the independent and joint effects of contralateral motor cortex tDCS (anodal vs cathodal) and socially induced expectations (analgesia vs hyperalgesia) about tDCS on thermal pain. We employed a double-blind, randomized 2 × 2 factorial cross-over design, with 5 sessions per participant on separate days. After calibration in Session 1, Sessions 2 to 5 crossed anodal or cathodal tDCS (20 minutes 2 mA) with socially induced analgesic or hyperalgesic expectations, with 6 to 7 days between the sessions. The social manipulation involved videos of previous "participants" (confederates) describing tDCS as inducing a low-pain state ("analgesic expectancy") or hypersensitivity to sensation ("hyperalgesic expectancy"). Anodal tDCS reduced pain compared with cathodal stimulation (F(1,19.9) = 19.53, P < 0.001, Cohen d = 0.86) and analgesic expectancy reduced pain compared with hyperalgesic expectancy (F(1,19.8) = 5.62, P = 0.027, Cohen d = 0.56). There was no significant interaction between tDCS and social expectations. Effects of social suggestions were related to expectations, whereas tDCS effects were unrelated to expectancies. The observed additive effects provide novel evidence that tDCS and socially induced expectations operate through independent processes. They extend clinical tDCS studies by showing tDCS effects on controlled nociceptive pain independent of expectancy effects. In addition, they show that social suggestions about neurostimulation effects can elicit potent placebo effects.
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Affiliation(s)
- Amin Dehghani
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States
| | - Carmen Bango
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States
| | - Ethan K Murphy
- Thayer School of Engineering and Geisel School of Medicine, Dartmouth College, Hanover, NH, United States
| | - Ryan J Halter
- Thayer School of Engineering and Geisel School of Medicine, Dartmouth College, Hanover, NH, United States
| | - Tor D Wager
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH, United States
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Caravati E, Barbeni F, Chiarion G, Raggi M, Mesin L. Closed-Loop Transcranial Electrical Neurostimulation for Sustained Attention Enhancement: A Pilot Study towards Personalized Intervention Strategies. Bioengineering (Basel) 2024; 11:467. [PMID: 38790334 PMCID: PMC11118513 DOI: 10.3390/bioengineering11050467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2024] [Revised: 05/03/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024] Open
Abstract
Sustained attention is pivotal for tasks like studying and working for which focus and low distractions are necessary for peak productivity. This study explores the effectiveness of adaptive transcranial direct current stimulation (tDCS) in either the frontal or parietal region to enhance sustained attention. The research involved ten healthy university students performing the Continuous Performance Task-AX (AX-CPT) while receiving either frontal or parietal tDCS. The study comprised three phases. First, we acquired the electroencephalography (EEG) signal to identify the most suitable metrics related to attention states. Among different spectral and complexity metrics computed on 3 s epochs of EEG, the Fuzzy Entropy and Multiscale Sample Entropy Index of frontal channels were selected. Secondly, we assessed how tDCS at a fixed 1.0 mA current affects attentional performance. Finally, a real-time experiment involving continuous metric monitoring allowed personalized dynamic optimization of the current amplitude and stimulation site (frontal or parietal). The findings reveal statistically significant improvements in mean accuracy (94.04 vs. 90.82%) and reaction times (262.93 vs. 302.03 ms) with the adaptive tDCS compared to a non-stimulation condition. Average reaction times were statistically shorter during adaptive stimulation compared to a fixed current amplitude condition (262.93 vs. 283.56 ms), while mean accuracy stayed similar (94.04 vs. 93.36%, improvement not statistically significant). Despite the limited number of subjects, this work points out the promising potential of adaptive tDCS as a tailored treatment for enhancing sustained attention.
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Affiliation(s)
| | | | | | | | - Luca Mesin
- Mathematical Biology and Physiology, Department Electronics and Telecommunications, Politecnico di Torino, 10129 Turin, Italy; (E.C.); (F.B.); (G.C.); (M.R.)
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Hooyman A, Haikalis NK, Wang P, Schambra HM, Lohse KR, Schaefer SY. Evidence and sources of placebo effects in transcranial direct current stimulation during a single session of visuospatial working memory practice. Sci Rep 2024; 14:9094. [PMID: 38643299 PMCID: PMC11032394 DOI: 10.1038/s41598-024-59927-2] [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: 02/21/2023] [Accepted: 04/16/2024] [Indexed: 04/22/2024] Open
Abstract
Transcranial direct current stimulation (tDCS) can be used to non-invasively augment cognitive training. However, the benefits of tDCS may be due in part to placebo effects, which have not been well-characterized. The purpose of this study was to determine whether tDCS can have a measurable placebo effect on cognitive training and to identify potential sources of this effect. Eighty-three right-handed adults were randomly assigned to one of three groups: control (no exposure to tDCS), sham tDCS, or active tDCS. The sham and active tDCS groups were double-blinded. Each group performed 20 min of an adapted Corsi Block Tapping Task (CBTT), a visuospatial working memory task. Anodal or sham tDCS was applied during CBTT training in a right parietal-left supraorbital montage. After training, active and sham tDCS groups were surveyed on expectations about tDCS efficacy. Linear mixed effects models showed that the tDCS groups (active and sham combined) improved more on the CBTT with training than the control group, suggesting a placebo effect of tDCS. Participants' tDCS expectations were significantly related to the placebo effect, as was the belief of receiving active stimulation. This placebo effect shows that the benefits of tDCS on cognitive training can occur even in absence of active stimulation. Future tDCS studies should consider how treatment expectations may be a source of the placebo effect in tDCS research, and identify ways to potentially leverage them to maximize treatment benefit.
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Affiliation(s)
- Andrew Hooyman
- School of Biological and Health Systems Engineering, Arizona State University, 501 E. Tyler Mall, MC 9709, Tempe, AZ, 85287, USA
| | - Nicole K Haikalis
- School of Biological and Health Systems Engineering, Arizona State University, 501 E. Tyler Mall, MC 9709, Tempe, AZ, 85287, USA
| | - Peiyuan Wang
- School of Biological and Health Systems Engineering, Arizona State University, 501 E. Tyler Mall, MC 9709, Tempe, AZ, 85287, USA
| | - Heidi M Schambra
- Department of Neurology and Department of Physical Medicine and Rehabilitation, Grossman School of Medicine, New York University, New York, NY, USA
| | - Keith R Lohse
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, USA
| | - Sydney Y Schaefer
- School of Biological and Health Systems Engineering, Arizona State University, 501 E. Tyler Mall, MC 9709, Tempe, AZ, 85287, USA.
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von Bastian CC, Hyde ERA, Jiang S. Tackling cognitive decline in late adulthood: Cognitive interventions. Curr Opin Psychol 2024; 56:101780. [PMID: 38176281 DOI: 10.1016/j.copsyc.2023.101780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/29/2023] [Accepted: 12/06/2023] [Indexed: 01/06/2024]
Abstract
Affordable and easy-to-administer interventions such as cognitive training, cognitively stimulating everyday leisure activities, and non-invasive brain stimulation techniques, are promising avenues to counteract age-related cognitive decline and support people in maintaining cognitive health into late adulthood. However, the same pattern of findings emerges across all three fields of cognitive intervention research: whereas improvements within the intervention context are large and often reliable, generalisation to other cognitive abilities and contexts are severely limited. These findings suggest that while cognitive interventions can enhance the efficiency with which people use their existing cognitive capacity, these interventions are unlikely to expand existing capacity limits. Therefore, future research investigating generalisation of enhanced efficiency constitutes a promising avenue for developing reliably effective cognitive interventions.
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Affiliation(s)
- Claudia C von Bastian
- Department of Psychology and Neuroscience Institute, University of Sheffield, United Kingdom.
| | - Eleanor R A Hyde
- Department of Psychology and Neuroscience Institute, University of Sheffield, United Kingdom
| | - Shuangke Jiang
- Department of Psychology and Neuroscience Institute, University of Sheffield, United Kingdom
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Fassi L, Hochman S, Daskalakis ZJ, Blumberger DM, Cohen Kadosh R. The importance of individual beliefs in assessing treatment efficacy. eLife 2024; 12:RP88889. [PMID: 38547008 PMCID: PMC10977967 DOI: 10.7554/elife.88889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024] Open
Abstract
In recent years, there has been debate about the effectiveness of treatments from different fields, such as neurostimulation, neurofeedback, brain training, and pharmacotherapy. This debate has been fuelled by contradictory and nuanced experimental findings. Notably, the effectiveness of a given treatment is commonly evaluated by comparing the effect of the active treatment versus the placebo on human health and/or behaviour. However, this approach neglects the individual's subjective experience of the type of treatment she or he received in establishing treatment efficacy. Here, we show that individual differences in subjective treatment - the thought of receiving the active or placebo condition during an experiment - can explain variability in outcomes better than the actual treatment. We analysed four independent datasets (N = 387 participants), including clinical patients and healthy adults from different age groups who were exposed to different neurostimulation treatments (transcranial magnetic stimulation: Studies 1 and 2; transcranial direct current stimulation: Studies 3 and 4). Our findings show that the inclusion of subjective treatment can provide a better model fit either alone or in interaction with objective treatment (defined as the condition to which participants are assigned in the experiment). These results demonstrate the significant contribution of subjective experience in explaining the variability of clinical, cognitive, and behavioural outcomes. We advocate for existing and future studies in clinical and non-clinical research to start accounting for participants' subjective beliefs and their interplay with objective treatment when assessing the efficacy of treatments. This approach will be crucial in providing a more accurate estimation of the treatment effect and its source, allowing the development of effective and reproducible interventions.
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Affiliation(s)
- Luisa Fassi
- MRC Cognition and Brain Sciences Unit, University of CambridgeCambridgeUnited Kingdom
- Department of Psychiatry, University of CambridgeCambridgeUnited Kingdom
- Department of Experimental Psychology, University of OxfordOxfordUnited Kingdom
| | - Shachar Hochman
- School of Psychology, University of SurreySurreyUnited Kingdom
| | - Zafiris J Daskalakis
- Department of Psychiatry, University of California, San DiegoSan DiegoUnited States
| | - Daniel M Blumberger
- Temerty Centre for Therapeutic Brain Intervention at the Centre for Addiction and Mental Health and Department of Psychiatry, Temerty Faculty of Medicine, University of TorontoTorontoCanada
| | - Roi Cohen Kadosh
- Department of Experimental Psychology, University of OxfordOxfordUnited Kingdom
- School of Psychology, University of SurreySurreyUnited Kingdom
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Jiang S, Jones M, von Bastian CC. TDCS over PPC or DLPFC does not improve visual working memory capacity. COMMUNICATIONS PSYCHOLOGY 2024; 2:20. [PMID: 39242793 PMCID: PMC11332112 DOI: 10.1038/s44271-024-00067-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 02/13/2024] [Indexed: 09/09/2024]
Abstract
Non-invasive brain stimulation has been highlighted as a possible intervention to induce cognitive benefits, including on visual working memory (VWM). However, findings are inconsistent, possibly due to methodological issues. A recent high-profile study by Wang et al.1 reported that anodal transcranial direct current stimulation (tDCS) over posterior parietal cortex (PPC), but not over dorsolateral prefrontal cortex (DLPFC), selectively improved VWM capacity but not precision, especially at a high VWM load. Thus, in the current pre-registered conceptual replication study, we accounted for the key potential methodological issues in the original study and tested an adequate number of participants required to demonstrate the previously reported effects (n = 48 compared to n = 20). Participants underwent counterbalanced PPC, DLPFC and sham stimulation before completing 360 trials of a continuous orientation-reproduction task with a slight variation of task stimuli and setup. We found no evidence for the selective effect of PPC stimulation. Instead, our results showed that tDCS effects were absent regardless of stimulation region and VWM load, which was largely supported by substantial to strong Bayesian evidence. Therefore, our results challenge previously reported benefits of single-session anodal PPC-tDCS on VWM.
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Affiliation(s)
- Shuangke Jiang
- Department of Psychology and Neuroscience Institute, University of Sheffield, Sheffield, UK.
| | - Myles Jones
- Department of Psychology and Neuroscience Institute, University of Sheffield, Sheffield, UK
| | - Claudia C von Bastian
- Department of Psychology and Neuroscience Institute, University of Sheffield, Sheffield, UK.
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Joshi SD, Ruffini G, Nuttall HE, Watson DG, Braithwaite JJ. Optimised Multi-Channel Transcranial Direct Current Stimulation (MtDCS) Reveals Differential Involvement of the Right-Ventrolateral Prefrontal Cortex (rVLPFC) and Insular Complex in those Predisposed to Aberrant Experiences. Conscious Cogn 2024; 117:103610. [PMID: 38056338 DOI: 10.1016/j.concog.2023.103610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/08/2023]
Abstract
Research has shown a prominent role for cortical hyperexcitability underlying aberrant perceptions, hallucinations, and distortions in human conscious experience - even in neurotypical groups. The rVLPFC has been identified as an important structure in mediating cognitive affective states / feeling conscious states. The current study examined the involvement of the rVLPFC in mediating cognitive affective states in those predisposed to aberrant experiences in the neurotypical population. Participants completed two trait-based measures: (i) the Cortical Hyperexcitability Index_II (CHi_II, a proxy measure of cortical hyperexcitability) and (ii) two factors from the Cambridge Depersonalisation Scale (CDS). An optimised 7-channel MtDCS montage for stimulation conditions (Anodal, Cathodal and Sham) was created targeting the rVLPFC in a single-blind study. At the end of each stimulation session, participants completed a body-threat task (BTAB) while skin conductance responses (SCRs) and psychological responses were recorded. Participants with signs of increasing cortical hyperexcitability showed significant suppression of SCRs in the Cathodal stimulation relative to the Anodal and sSham conditions. Those high on the trait-based measures of depersonalisation-like experiences failed to show reliable effects. Collectively, the findings suggest that baseline brain states can mediate the effects of neurostimulation which would be missed via sample level averaging and without appropriate measures for stratifying individual differences.
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10
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Ankri YLE, Braw YC, Meiron O. Stress and Right Prefrontal Transcranial Direct Current Stimulation (tDCS) Interactive Effects on Visual Working Memory and Learning. Brain Sci 2023; 13:1642. [PMID: 38137090 PMCID: PMC10741696 DOI: 10.3390/brainsci13121642] [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: 10/31/2023] [Revised: 11/16/2023] [Accepted: 11/24/2023] [Indexed: 12/24/2023] Open
Abstract
Stress impacts prefrontal cortex (PFC) activity and modulates working memory performance. In a recent study, stimulating the dorsolateral PFC (dlPFC) using transcranial direct current stimulation (tDCS) interacted with social stress in modulating participants' working memory. More specifically, stress disrupted the enhancing effects of dlPFC tDCS on working memory performance. The current study aimed to further explore these initial findings by randomizing healthy females to four experimental conditions (N = 130); stimulation (right dlPFC tDCS vs. sham) and stress manipulation (social stress vs. control). Participants performed cognitive tasks (i.e., visual working memory task and a visual declarative memory task) at baseline and post-stimulation. They also completed self-report measures of stress and anxiety. A significant stimulation × stress interaction was evident in the declarative memory (One-Card Learning, OCL) task, while working memory performance was unaffected. Though tDCS stimulation and stress did not interact to affect working memory, further research is warranted as these initial findings suggest that immediate visual-memory learning may be affected by these factors. The limited number of earlier studies, as well as the variability in their designs, provides additional impetus for studying the interactive effects of stress and tDCS on human visual learning.
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Affiliation(s)
- Yael L. E. Ankri
- Department of Psychology, Ariel University, Ariel 4077625, Israel; (Y.L.E.A.); (Y.C.B.)
| | - Yoram C. Braw
- Department of Psychology, Ariel University, Ariel 4077625, Israel; (Y.L.E.A.); (Y.C.B.)
| | - Oded Meiron
- Faculty of Education, Bar-Ilan University, Ramat-Gan 5290002, Israel
- Clinical Research Center for Brain Sciences, Herzog Medical Center, P.O. Box 3900, Jerusalem 9103702, Israel
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11
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Gorrino I, Canessa N, Mattavelli G. Testing the effect of high-definition transcranial direct current stimulation of the insular cortex to modulate decision-making and executive control. Front Behav Neurosci 2023; 17:1234837. [PMID: 37840546 PMCID: PMC10568024 DOI: 10.3389/fnbeh.2023.1234837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 09/12/2023] [Indexed: 10/17/2023] Open
Abstract
Introduction Previous neuroimaging evidence highlighted the role of the insular and dorsal anterior cingulate cortex (dACC) in conflict monitoring and decision-making, thus supporting the translational implications of targeting these regions in neuro-stimulation treatments for clinical purposes. Recent advancements of targeting and modeling procedures for high-definition tDCS (HD-tDCS) provided methodological support for the stimulation of otherwise challenging targets, and a previous study confirmed that cathodal HD-tDCS of the dACC modulates executive control and decision-making metrics in healthy individuals. On the other hand, evidence on the effect of stimulating the insula is still needed. Methods We used a modeling/targeting procedure to investigate the effect of stimulating the posterior insula on Flanker and gambling tasks assessing, respectively, executive control and both loss and risk aversion in decision-making. HD-tDCS was applied through 6 small electrodes delivering anodal, cathodal or sham stimulation for 20 min in a within-subject offline design with three separate sessions. Results Bayesian statistical analyses on Flanker conflict effect, as well as loss and risk aversion, provided moderate evidence for the null model (i.e., absence of HD-tDCS modulation). Discussion These findings suggest that further research on the effect of HD-tDCS on different regions is required to define reliable targets for clinical applications. While modeling and targeting procedures for neuromodulation in clinical research could lead to innovative protocols for stand-alone treatment, or possibly in combination with cognitive training, assessing the effectiveness of insula stimulation might require sensitive metrics other than those investigated here.
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Affiliation(s)
- Irene Gorrino
- IUSS Cognitive Neuroscience (ICoN) Center, Scuola Universitaria Superiore IUSS, Pavia, Italy
| | - Nicola Canessa
- IUSS Cognitive Neuroscience (ICoN) Center, Scuola Universitaria Superiore IUSS, Pavia, Italy
- Istituti Clinici Scientifici Maugeri IRCCS, Cognitive Neuroscience Laboratory of Pavia Institute, Pavia, Italy
| | - Giulia Mattavelli
- IUSS Cognitive Neuroscience (ICoN) Center, Scuola Universitaria Superiore IUSS, Pavia, Italy
- Istituti Clinici Scientifici Maugeri IRCCS, Cognitive Neuroscience Laboratory of Pavia Institute, Pavia, Italy
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Klees-Themens G, Théoret H. The effects of transcranial direct current stimulation on corticospinal excitability: A systematic review of nonsignificant findings. Eur J Neurosci 2023; 58:3074-3097. [PMID: 37407275 DOI: 10.1111/ejn.16073] [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: 11/14/2022] [Revised: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 07/07/2023]
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can modulate brain activity through the application of low-intensity electrical currents. Based on its reported effects on corticospinal excitability (CSE), tDCS has been used to study cognition in healthy individuals and reduce symptoms in a variety of clinical conditions. Despite its increasing popularity as a research and clinical tool, high interindividual variability has been reported in the response to protocols using transcranial magnetic stimulation (TMS) to assess tDCS-induced changes in CSE leading to several nonsignificant findings. In this systematic review, studies that reported no significant modulation of CSE following tDCS were identified from PubMed and Embase (Ovid) databases. Forty-three articles were identified where demographic, TMS and tDCS parameters were extracted. Overall, stimulation parameters, CSE measurements and participant characteristics were similar to those described in studies reporting positive results and were likewise heterogeneous between studies. Small sample sizes and inadequate blinding were notable features of the reviewed studies. This systematic review suggests that studies reporting nonsignificant findings do not markedly differ from those reporting significant modulation of CSE.
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Affiliation(s)
| | - Hugo Théoret
- Department of Psychology, Université de Montréal, Montreal, Québec, Canada
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13
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Rauh J, Müller ASM, Nolte G, Haaf M, Mußmann M, Steinmann S, Mulert C, Leicht G. Comparison of transcranial brain stimulation approaches: prefrontal theta alternating current stimulation enhances working memory performance. Front Psychiatry 2023; 14:1140361. [PMID: 37457770 PMCID: PMC10348840 DOI: 10.3389/fpsyt.2023.1140361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 06/05/2023] [Indexed: 07/18/2023] Open
Abstract
Introduction One of the most important cognitive functions in our everyday life is the working memory (WM). In several neuropsychiatric diseases such as ADHD or schizophrenia WM deficits can be observed, making it an attractive target for non-invasive brain stimulation methods like transcranial electrical stimulation (tES). However, the literature shows rather heterogeneous results of tES effects on WM performance. fMRI meta-analyses have identified a WM network including frontoparietal brain areas such as the dorsolateral prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC). Neurophysiological studies revealed oscillatory activity in the theta band frequency range to be of crucial functional relevance for WM processes. Based on this, transcranial alternating current stimulation (tACS) in the theta frequency range targeting DLPFC and PPC in a spatially optimized way might further improve effects of tES on WM performance. Methods Sixteen healthy subjects were stimulated with varying stimulation settings on four different days in a counterbalanced within-subject design. These setups included the application of (1) tACS with a frequency of 5 Hz (theta frequency range) over the left DLPFC and (2) the right superior parietal cortex, (3) transcranial direct current stimulation (tDCS) of the DLPFC and (4) a sham stimulation condition during the online performance of a visual delayed-match-to-sample task with varying working memory load. We introduce a procedure to calculate an optimal tES model revealing optimized high-density setups for the present study for 3 cathodes and 1 anode and stimulation currents of 1.5 mA. Results A significant interaction effect of stimulation type and load condition on working memory capacity was found. This was reflected by a significant improvement of WM performance in the high load condition during tACS over the left DLPFC compared with sham stimulation, which was not the case for our parietal tACS or tDCS setup. Discussion Working memory performance can be improved with optimized high-definition tACS with a frequency of 5 Hz over the left DLPFC. The conception of different mechanisms underlying transcranial electrical stimulation with alternating and direct currents is supported by these results. Patients suffering from working memory impairments due to neuropsychiatric diseases might potentially benefit from this brain stimulation approach.
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Affiliation(s)
- Jonas Rauh
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anne S. M. Müller
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Guido Nolte
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Moritz Haaf
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marius Mußmann
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Saskia Steinmann
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Mulert
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Center of Psychiatry, Justus-Liebig University, Giessen, Germany
| | - Gregor Leicht
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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14
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Majdi A, Asamoah B, Mc Laughlin M. Reinterpreting published tDCS results in terms of a cranial and cervical nerve co-stimulation mechanism. Front Hum Neurosci 2023; 17:1101490. [PMID: 37415857 PMCID: PMC10320219 DOI: 10.3389/fnhum.2023.1101490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 05/31/2023] [Indexed: 07/08/2023] Open
Abstract
Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation method that has been used to alter cognition in hundreds of experiments. During tDCS, a low-amplitude current is delivered via scalp electrodes to create a weak electric field in the brain. The weak electric field causes membrane polarization in cortical neurons directly under the scalp electrodes. It is generally assumed that this mechanism causes the observed effects of tDCS on cognition. However, it was recently shown that some tDCS effects are not caused by the electric field in the brain but rather via co-stimulation of cranial and cervical nerves in the scalp that also have neuromodulatory effects that can influence cognition. This peripheral nerve co-stimulation mechanism is not controlled for in tDCS experiments that use the standard sham condition. In light of this new evidence, results from previous tDCS experiments could be reinterpreted in terms of a peripheral nerve co-stimulation mechanism. Here, we selected six publications that reported tDCS effects on cognition and attributed the effects to the electric field in the brain directly under the electrode. We then posed the question: given the known neuromodulatory effects of cranial and cervical nerve stimulation, could the reported results also be understood in terms of tDCS peripheral nerve co-stimulation? We present our re-interpretation of these results as a way to stimulate debate within the neuromodulation field and as a food-for-thought for researchers designing new tDCS experiments.
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Affiliation(s)
- Alireza Majdi
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Boateng Asamoah
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Myles Mc Laughlin
- Exp ORL, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
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15
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Blagovechtchenski E, Kostromina S, Shaboltas A. Using a Pulse Protocol to Fix the Individual Dosage of Transcranial and Transspinal Direct Current Electrical Stimulation. Life (Basel) 2023; 13:1376. [PMID: 37374158 DOI: 10.3390/life13061376] [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: 05/09/2023] [Revised: 06/04/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
The non-invasive current stimulation protocol differs significantly between the brain and spinal cord, such that when comparing the two, there is a clear predominance of protocols using transcranial direct current stimulation (tDCS) for the brain and of protocols using pulsed stimulation for the spinal cord (psSC). These protocols differ in their effects on the central nervous system and in such important parameters as stimulation intensity. In most cases, tDCS has a fixed amplitude for all subjects/patients, while psSC is usually chosen on a case-by-case basis, according to the thresholds of muscle responses. In our opinion, it is possible to use the experience of identifying thresholds during psSC to adjust the dose of the direct current for transcranial and transspinal electrical stimulation, an approach that may provide more homogeneous tDCS data.
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Affiliation(s)
- Evgeny Blagovechtchenski
- Laboratory of Behavioural Neurodynamics, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Svetlana Kostromina
- Laboratory of Behavioural Neurodynamics, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Alla Shaboltas
- Laboratory of Behavioural Neurodynamics, St. Petersburg State University, St. Petersburg 199034, Russia
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16
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Spooner RK, Wilson TW. Spectral specificity of gamma-frequency transcranial alternating current stimulation over motor cortex during sequential movements. Cereb Cortex 2023; 33:5347-5360. [PMID: 36368895 PMCID: PMC10152093 DOI: 10.1093/cercor/bhac423] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 11/13/2022] Open
Abstract
Motor control requires the coordination of spatiotemporally precise neural oscillations in the beta and gamma range within the primary motor cortex (M1). Recent studies have shown that motor performance can be differentially modulated based on the spectral target of noninvasive transcranial alternating current stimulation (tACS), with gamma-frequency tACS improving motor performance. However, the spectral specificity for eliciting such improvements remains unknown. Herein, we derived the peak movement-related gamma frequency in 25 healthy adults using magnetoencephalography and a motor control paradigm. These individualized peak gamma frequencies were then used for personalized sessions of tACS. All participants completed 4 sessions of high-definition (HD)-tACS (sham, low-, peak-, and high-gamma frequency) over M1 for 20 min during the performance of sequential movements of varying complexity (e.g. tapping adjacent fingers or nonadjacent fingers). Our primary findings demonstrated that individualized tACS dosing over M1 leads to enhanced motor performance/learning (i.e. greatest reduction in time to complete motor sequences) compared to nonspecific gamma-tACS in humans, which suggests that personalized neuromodulation may be advantageous to optimize behavioral outcomes.
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Affiliation(s)
- Rachel K Spooner
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- College of Medicine, University of Nebraska Medical Center (UMNC), Omaha, NE, United States
- Institute of Clinical Neuroscience and Medical Psychology, Heinrich-Heine University, Düsseldorf, Germany
| | - Tony W Wilson
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, United States
- College of Medicine, University of Nebraska Medical Center (UMNC), Omaha, NE, United States
- Center for Pediatric Brain Health, Boys Town National Research Hospital, Boys Town, NE, United States
- Department of Pharmacology & Neuroscience, Creighton University, Omaha, NE, United States
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17
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Kuffler DP. Evolving techniques for reducing phantom limb pain. Exp Biol Med (Maywood) 2023; 248:561-572. [PMID: 37158119 PMCID: PMC10350801 DOI: 10.1177/15353702231168150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
At least two million people in the United States of America live with lost limbs, and the number is expected to double by 2050, although the incidence of amputations is significantly greater in other parts of the world. Within days to weeks of the amputation, up to 90% of these individuals develop neuropathic pain, presenting as phantom limb pain (PLP). The pain level increases significantly within one year and remains chronic and severe for about 10%. Amputation-induced changes are considered to underlie the causation of PLP. Techniques applied to the central nervous system (CNS) and peripheral nervous system (PNS) are designed to reverse amputation-induced changes, thereby reducing/eliminating PLP. The primary treatment for PLP is the administration of pharmacological agents, some of which are considered but provide no more than short-term pain relief. Alternative techniques are also discussed, which provide only short-term pain relief. Changes induced by various cells and the factors they release are required to change neurons and their environment to reduce/eliminate PLP. It is concluded that novel techniques that utilize autologous platelet-rich plasma (PRP) may provide long-term PLP reduction/elimination.
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Affiliation(s)
- Damien P Kuffler
- Institute of Neurobiology, Medical Sciences Campus, University of Puerto Rico, San Juan 00901, Puerto Rico
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18
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Hunold A, Haueisen J, Nees F, Moliadze V. Review of individualized current flow modeling studies for transcranial electrical stimulation. J Neurosci Res 2023; 101:405-423. [PMID: 36537991 DOI: 10.1002/jnr.25154] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 11/30/2022] [Accepted: 12/03/2022] [Indexed: 12/24/2022]
Abstract
There is substantial intersubject variability of behavioral and neurophysiological responses to transcranial electrical stimulation (tES), which represents one of the most important limitations of tES. Many tES protocols utilize a fixed experimental parameter set disregarding individual anatomical and physiological properties. This one-size-fits-all approach might be one reason for the observed interindividual response variability. Simulation of current flow applying head models based on available anatomical data can help to individualize stimulation parameters and contribute to the understanding of the causes of this response variability. Current flow modeling can be used to retrospectively investigate the characteristics of tES effectivity. Previous studies examined, for example, the impact of skull defects and lesions on the modulation of current flow and demonstrated effective stimulation intensities in different age groups. Furthermore, uncertainty analysis of electrical conductivities in current flow modeling indicated the most influential tissue compartments. Current flow modeling, when used in prospective study planning, can potentially guide stimulation configurations resulting in individually effective tES. Specifically, current flow modeling using individual or matched head models can be employed by clinicians and scientists to, for example, plan dosage in tES protocols for individuals or groups of participants. We review studies that show a relationship between the presence of behavioral/neurophysiological responses and features derived from individualized current flow models. We highlight the potential benefits of individualized current flow modeling.
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Affiliation(s)
- Alexander Hunold
- Institute of Biomedical Engineering and Informatics, TU Ilmenau, Ilmenau, Germany
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, TU Ilmenau, Ilmenau, Germany
| | - Frauke Nees
- Institute of Medical Psychology and Medical Sociology, University Medical Center Schleswig Holstein, Kiel University, Kiel, Germany
| | - Vera Moliadze
- Institute of Medical Psychology and Medical Sociology, University Medical Center Schleswig Holstein, Kiel University, Kiel, Germany
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19
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Menze I, Mueller NG, Zaehle T, Schmicker M. Individual response to transcranial direct current stimulation as a function of working memory capacity and electrode montage. Front Hum Neurosci 2023; 17:1134632. [PMID: 36968784 PMCID: PMC10034341 DOI: 10.3389/fnhum.2023.1134632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 02/01/2023] [Indexed: 03/11/2023] Open
Abstract
IntroductionAttempts to improve cognitive abilities via transcranial direct current stimulation (tDCS) have led to ambiguous results, likely due to the method’s susceptibility to methodological and inter-individual factors. Conventional tDCS, i.e., using an active electrode over brain areas associated with the targeted cognitive function and a supposedly passive reference, neglects stimulation effects on entire neural networks.MethodsWe investigated the advantage of frontoparietal network stimulation (right prefrontal anode, left posterior parietal cathode) against conventional and sham tDCS in modulating working memory (WM) capacity dependent transfer effects of a single-session distractor inhibition (DIIN) training. Since previous results did not clarify whether electrode montage drives this individual transfer, we here compared conventional to frontoparietal and sham tDCS and reanalyzed data of 124 young, healthy participants in a more robust way using linear mixed effect modeling.ResultsThe interaction of electrode montage and WM capacity resulted in systematic differences in transfer effects. While higher performance gains were observed with increasing WM capacity in the frontoparietal stimulation group, low WM capacity individuals benefited more in the sham condition. The conventional stimulation group showed subtle performance gains independent of WM capacity.DiscussionOur results confirm our previous findings of WM capacity dependent transfer effects on WM by a single-session DIIN training combined with tDCS and additionally highlight the pivotal role of the specific electrode montage. WM capacity dependent differences in frontoparietal network recruitment, especially regarding the parietal involvement, are assumed to underlie this observation.
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Affiliation(s)
- Inga Menze
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- *Correspondence: Inga Menze,
| | - Notger G. Mueller
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Research Group Degenerative and Chronic Diseases, Movement, Faculty of Health Sciences Brandenburg, University of Potsdam, Potsdam, Germany
| | - Tino Zaehle
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
| | - Marlen Schmicker
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
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20
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Nikolin S, Martin D, Loo CK, Boonstra TW. Transcranial Direct Current Stimulation Modulates Working Memory Maintenance Processes in Healthy Individuals. J Cogn Neurosci 2023; 35:468-484. [PMID: 36603051 DOI: 10.1162/jocn_a_01957] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effects of transcranial direct current stimulation (tDCS) at the pFC are often investigated using cognitive paradigms, particularly working memory tasks. However, the neural basis for the neuromodulatory cognitive effects of tDCS, including which subprocesses are affected by stimulation, is not completely understood. We investigated the effects of tDCS on working memory task-related spectral activity during and after tDCS to gain better insights into the neurophysiological changes associated with stimulation. We reanalyzed data from 100 healthy participants grouped by allocation to receive either sham (0 mA, 0.016 mA, and 0.034 mA) or active (1 mA or 2 mA) stimulation during a 3-back task. EEG data were used to analyze event-related spectral power in frequency bands associated with working memory performance. Frontal theta event-related synchronization (ERS) was significantly reduced post-tDCS in the active group. Participants receiving active tDCS had slower RTs following tDCS compared with sham, suggesting interference with practice effects associated with task repetition. Theta ERS was not significantly correlated with RTs or accuracy. tDCS reduced frontal theta ERS poststimulation, suggesting a selective disruption to working memory cognitive control and maintenance processes. These findings suggest that tDCS selectively affects specific subprocesses during working memory, which may explain heterogenous behavioral effects.
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Affiliation(s)
- Stevan Nikolin
- University of New South Wales, Sydney, Australia
- Black Dog Institute, Sydney, New South Wales, Australia
| | - Donel Martin
- University of New South Wales, Sydney, Australia
- Black Dog Institute, Sydney, New South Wales, Australia
| | - Colleen K Loo
- University of New South Wales, Sydney, Australia
- Black Dog Institute, Sydney, New South Wales, Australia
| | - Tjeerd W Boonstra
- University of New South Wales, Sydney, Australia
- Maastricht University, The Netherlands
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21
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Balboa-Bandeira Y, Zubiaurre-Elorza L, García-Guerrero MA, Ibarretxe-Bilbao N, Ojeda N, Peña J. Effects of transcranial electrical stimulation techniques on foreign vocabulary learning. Behav Brain Res 2023; 438:114165. [PMID: 36270464 DOI: 10.1016/j.bbr.2022.114165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 09/12/2022] [Accepted: 10/15/2022] [Indexed: 11/05/2022]
Abstract
Although the use of transcranial electrical stimulation (tES) techniques on healthy population has been linked to facilitating language learning, studies on their effects on foreign language learning processes are scarce and results remain unclear. The objective of this study was to analyze whether tES enhances foreign language learning processes. Sixty-four healthy native Spanish-speaking participants were randomly assigned to four groups (transcranial direct current, transcranial random noise, tDCS-tRNS stimulation, or sham). They completed two intervention sessions with a two-week gap in between. During the first session the participants received stimulation (1.5 mA) while learning new English words and then performed recall and recognition tasks. Learning was assessed at follow-up, two weeks later. No differences in learning between groups were observed in the first session (F(1,61)= .86; p = .36). At follow-up, significantly higher learning accuracy was observed after tRNS compared to sham (p = .037). These results suggest that tRNS could be helpful in improving the processes involved in foreign language vocabulary learning.
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Affiliation(s)
- Yolanda Balboa-Bandeira
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain
| | - Leire Zubiaurre-Elorza
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain
| | - M Acebo García-Guerrero
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain
| | - Naroa Ibarretxe-Bilbao
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain
| | - Natalia Ojeda
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain
| | - Javier Peña
- Department of Methods and Experimental Psychology, Faculty of Health Sciences, University of Deusto, Bilbao, Spain.
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22
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Optimized APPS-tDCS electrode position, size, and distance doubles the on-target stimulation magnitude in 3000 electric field models. Sci Rep 2022; 12:20116. [PMID: 36418438 PMCID: PMC9684449 DOI: 10.1038/s41598-022-24618-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 11/17/2022] [Indexed: 11/24/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a widely used noninvasive brain stimulation technique with mixed results to date. A potential solution is to apply more efficient stimulation to ensure that each participant receives sufficient cortical activation. In this four-part study, we used electric field (E-field) modeling to systematically investigate the cortical effects of conventional and novel tDCS electrode montages, with the goal of creating a new easily adoptable form of tDCS that induces higher and more focal E-fields. We computed 3000 anatomically accurate, MRI-based E-field models using 2 mA tDCS to target the left primary motor cortex in 200 Human Connectome Project (HCP) participants and tested the effects of: 1. Novel Electrode Position, 2. Electrode Size, and 3. Inter-Electrode Distance on E-field magnitude and focality. In particular, we examined the effects of placing electrodes surrounding the corticomotor target in the anterior and posterior direction (anterior posterior pad surround tDCS; APPS-tDCS). We found that electrode position, electrode size, and inter-electrode distance all significantly impact the cortical E-field magnitude and focality of stimulation (all p < 0.0001). At the same 2 mA scalp stimulation intensity, APPS-tDCS with smaller than conventional 1 × 1 cm electrodes surrounding the neural target deliver more than double the on-target cortical E-field (APPS-tDCS: average of 0.55 V/m from 2 mA; M1-SO and bilateral M1: both 0.27 V/m from 2 mA) while stimulating only a fraction of the off-target brain regions; 2 mA optimized APPS-tDCS produces 4.08 mA-like cortical E-fields. In sum, this new optimized APPS-tDCS method produces much stronger cortical stimulation intensities at the same 2 mA scalp intensity. APPS-tDCS also more focally stimulates the cortex at the intended target, using simple EEG coordinate locations and without MRI scans. This APPS-tDCS method is adoptable to any existing, commercially available tDCS device and can be used to ensure sufficient cortical activation in each person. Future directions include testing whether APPS-tDCS produces larger and more consistent therapeutic tDCS effects.
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23
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Jones KT, Johnson EL, Gazzaley A, Zanto TP. Structural and functional network mechanisms of rescuing cognitive control in aging. Neuroimage 2022; 262:119547. [PMID: 35940423 PMCID: PMC9464721 DOI: 10.1016/j.neuroimage.2022.119547] [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: 02/07/2022] [Revised: 07/13/2022] [Accepted: 08/04/2022] [Indexed: 11/23/2022] Open
Abstract
Age-related declines in cognitive control, an ability critical in most daily tasks, threaten individual independence. We previously showed in both older and younger adults that transcranial alternating current stimulation (tACS) can improve cognitive control, with effects observed across neural regions distant from the stimulated site and frequencies outside the stimulated range. Here, we assess network-level changes in neural activity that extend beyond the stimulated site and evaluate anatomical pathways that subserve these effects. We investigated the potential to rescue cognitive control in aging using prefrontal (F3-F4) theta (6 Hz) or control (1 Hz) tACS while older adults engaged in a cognitive control video game intervention on three consecutive days. Functional connectivity was assessed with EEG by measuring daily changes in frontal-posterior phase-locking values (PLV) from the tACS-free baseline. Structural connectivity was measured using MRI diffusion tractography data collected at baseline. Theta tACS improved multitasking performance, and individual gains reflected a dissociation in daily PLV changes, where theta tACS strengthened PLV and control tACS reduced PLV. Strengthened alpha-beta PLV in the theta tACS group correlated positively with inferior longitudinal fasciculus and corpus callosum body integrity, and further explained multitasking gains. These results demonstrate that theta tACS can improve cognitive control in aging by strengthening functional connectivity, particularly in higher frequency bands. However, the extent of functional connectivity gains is limited by the integrity of structural white matter tracts. Given that advanced age is associated with decreased white matter integrity, results suggest that the deployment of tACS as a therapeutic is best prior to advanced age.
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Affiliation(s)
- Kevin T Jones
- Department of Neurology, University of California-San Francisco, San Francisco, California; Neuroscape, University of California-San Francisco, San Francisco, California.
| | - Elizabeth L Johnson
- Departments of Medical Social Sciences and Pediatrics, Northwestern University, Chicago, Illinois
| | - Adam Gazzaley
- Department of Neurology, University of California-San Francisco, San Francisco, California; Neuroscape, University of California-San Francisco, San Francisco, California; Departments of Physiology and Psychiatry, University of California-San Francisco, San Francisco, California
| | - Theodore P Zanto
- Department of Neurology, University of California-San Francisco, San Francisco, California; Neuroscape, University of California-San Francisco, San Francisco, California
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24
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Voegtle A, Reichert C, Hinrichs H, Sweeney-Reed CM. Repetitive Anodal TDCS to the Frontal Cortex Increases the P300 during Working Memory Processing. Brain Sci 2022; 12:1545. [PMID: 36421869 PMCID: PMC9688092 DOI: 10.3390/brainsci12111545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/05/2022] [Accepted: 11/07/2022] [Indexed: 10/17/2023] Open
Abstract
Transcranial direct current stimulation (TDCS) is a technique with which neuronal activity, and therefore potentially behavior, is modulated by applying weak electrical currents to the scalp. Application of TDCS to enhance working memory (WM) has shown promising but also contradictory results, and little emphasis has been placed on repeated stimulation protocols, in which effects are expected to be increased. We aimed to characterize potential behavioral and electrophysiological changes induced by TDCS during WM training and evaluate whether repetitive anodal TDCS has a greater modulatory impact on the processes underpinning WM than single-session stimulation. We examined the effects of single-session and repetitive anodal TDCS to the dorsolateral prefrontal cortex (DLPFC), targeting the frontal-parietal network, during a WM task in 20 healthy participants. TDCS had no significant impact on behavioral measures, including reaction time and accuracy. Analyzing the electrophysiological response, the P300 amplitude significantly increased following repetitive anodal TDCS, however, positively correlating with task performance. P300 changes were identified over the parietal cortex, which is known to engage with the frontal cortex during WM processing. These findings support the hypothesis that repetitive anodal TDCS modulates electrophysiological processes underlying WM.
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Affiliation(s)
- Angela Voegtle
- Neurocybernetics and Rehabilitation, Department of Neurology, Otto von Guericke University, 39120 Magdeburg, Germany
| | - Christoph Reichert
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Center for Behavioral Brain Sciences—CBBS, Otto von Guericke University, 39106 Magdeburg, Germany
| | - Hermann Hinrichs
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
- Center for Behavioral Brain Sciences—CBBS, Otto von Guericke University, 39106 Magdeburg, Germany
- Department of Neurology, Otto von Guericke University, 39120 Magdeburg, Germany
| | - Catherine M. Sweeney-Reed
- Neurocybernetics and Rehabilitation, Department of Neurology, Otto von Guericke University, 39120 Magdeburg, Germany
- Center for Behavioral Brain Sciences—CBBS, Otto von Guericke University, 39106 Magdeburg, Germany
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25
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Martin DM, Berryhill ME, Dielenberg V. Can brain stimulation enhance cognition in clinical populations? A critical review. Restor Neurol Neurosci 2022:RNN211230. [PMID: 36404559 DOI: 10.3233/rnn-211230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Many psychiatric and neurological conditions are associated with cognitive impairment for which there are very limited treatment options. Brain stimulation methodologies show promise as novel therapeutics and have cognitive effects. Electroconvulsive therapy (ECT), known more for its related transient adverse cognitive effects, can produce significant cognitive improvement in the weeks following acute treatment. Transcranial magnetic stimulation (TMS) is increasingly used as a treatment for major depression and has acute cognitive effects. Emerging research from controlled studies suggests that repeated TMS treatments may additionally have cognitive benefit. ECT and TMS treatment cause neurotrophic changes, although whether these are associated with cognitive effects remains unclear. Transcranial electrical stimulation methods including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) are in development as novel treatments for multiple psychiatric conditions. These treatments may also produce cognitive enhancement particularly when stimulation occurs concurrently with a cognitive task. This review summarizes the current clinical evidence for these brain stimulation treatments as therapeutics for enhancing cognition. Acute, or short-lasting, effects as well as longer-term effects from repeated treatments are reviewed, together with potential putative neural mechanisms. Areas of future research are highlighted to assist with optimization of these approaches for enhancing cognition.
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Affiliation(s)
- Donel M. Martin
- Sydney Neurostimulation Centre, Discipline of Psychiatry and Mental Health UNSW, Black Dog Institute, Sydney, New South Wales, Australia
| | - Marian E. Berryhill
- Memory and Brain Lab, Programs in Cognitive and Brain Sciences, and Integrative Neuroscience, University of Nevada, Reno, NV, USA
| | - Victoria Dielenberg
- Sydney Neurostimulation Centre, Discipline of Psychiatry and Mental Health UNSW, Black Dog Institute, Sydney, New South Wales, Australia
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26
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Calin-Jageman RJ. Better Inference in Neuroscience: Test Less, Estimate More. J Neurosci 2022; 42:8427-8431. [PMID: 36351833 PMCID: PMC9665913 DOI: 10.1523/jneurosci.1133-22.2022] [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: 06/10/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 11/17/2022] Open
Abstract
Null-hypothesis significance testing (NHST) has become the main tool of inference in neuroscience, and yet evidence suggests we do not use this tool well: tests are often planned poorly, conducted unfairly, and interpreted invalidly. This editorial makes the case that in addition to reforms to increase rigor we should test less, reserving NHST for clearly confirmatory contexts in which the researcher has derived a quantitative prediction, can provide the inputs needed to plan a quality test, and can specify the criteria not only for confirming their hypothesis but also for rejecting it. A reduction in testing would be accompanied by an expansion of the use of estimation [effect sizes and confidence intervals (CIs)]. Estimation is more suitable for exploratory research, provides the inputs needed to plan strong tests, and provides important contexts for properly interpreting tests.
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Attention neuroenhancement through tDCS or neurofeedback: a randomized, single-blind, controlled trial. Sci Rep 2022; 12:17613. [PMID: 36266396 PMCID: PMC9584934 DOI: 10.1038/s41598-022-22245-6] [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] [Received: 03/15/2022] [Accepted: 10/12/2022] [Indexed: 01/13/2023] Open
Abstract
Neurofeedback and transcranial Direct Current Stimulation (tDCS) are promising techniques for neuroenhancement of attentional performance. As far as we know no study compared both techniques on attentional performance in healthy participants. We compared tDCS and neurofeedback in a randomized, single-blind, controlled experiment assessing both behavioral (accuracy and time reaction) and electrophysiological (N1, P1, and P3 components) data of participants responding to the Attention Network Task (ANT). Eighty volunteers volunteered for this study. We adopted standard protocols for both techniques, i.e., a Sensorimotor Rhythm (SMR) protocol for neurofeedback and the right DLPFC anodal stimulation for tDCS, applied over nine sessions (two weeks). We did not find significant differences between treatment groups on ANT, neither at the behavioral nor at the electrophysiological levels. However, we found that participants from both neuromodulation groups, irrespective of if active or sham, reported attentional improvements in response to the treatment on a subjective scale. Our study adds another null result to the neuromodulation literature, showing that neurofeedback and tDCS effects are more complex than previously suggested and associated with placebo effect. More studies in neuroenhancement literature are necessary to fully comprehend neuromodulation mechanisms.
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28
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The effects of concurrent bilateral anodal tDCS of primary motor cortex and cerebellum on corticospinal excitability: a randomized, double-blind sham-controlled study. Brain Struct Funct 2022; 227:2395-2408. [PMID: 35984496 PMCID: PMC9418272 DOI: 10.1007/s00429-022-02533-7] [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] [Received: 06/28/2021] [Accepted: 06/30/2022] [Indexed: 11/11/2022]
Abstract
Transcranial direct current stimulation (tDCS) applied to the primary motor cortex (M1), and cerebellum (CB) can change the level of M1 corticospinal excitability (CSE). A randomized double-blinded crossover, the sham-controlled study design was used to investigate the effects of concurrent bilateral anodal tDCS of M1 and CB (concurrent bilateral a-tDCSM1+CB) on the CSE. Twenty-one healthy participants were recruited in this study. Each participant received anodal-tDCS (a-tDCS) of 2 mA, 20 min in four pseudo-randomized, counterbalanced sessions, separated by at least 7 days (7.11 days ± 0.65). These sessions were bilateral M1 stimulation (bilateral a-tDCSM1), bilateral cerebellar stimulation (bilateral a-tDCSCB), concurrent bilateral a-tDCSM1+CB, and sham stimulation (bilateral a-tDCSSham). Transcranial magnetic stimulation (TMS) was delivered over the left M1, and motor evoked potentials (MEPs) of a contralateral hand muscle were recorded before and immediately after the intervention to measure CSE changes. Short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and long interval intracortical inhibition (LICI) were assessed with paired-pulse TMS protocols. Anodal-tDCS significantly increased CSE after concurrent bilateral a-tDCSM1+CB and bilateral a-tDCSCB. Interestingly, CSE was decreased after bilateral a-tDCSM1. Respective alterations in SICI, LICI, and ICF were seen, including increased SICI and decreased ICF, which indicate the involvement of glutamatergic and GABAergic systems in these effects. These results confirm that the concurrent bilateral a-tDCSM1+CB have a facilitatory effect on CSE, whereas bilateral a-tDCSM1 exert some inhibitory effects. Moreover, the effects of the 2 mA, 20 min a-tDCS on the CB were consistent with its effects on the M1.
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Sansevere KS, Wooten T, McWilliams T, Peach S, Hussey EK, Brunyé TT, Ward N. Self-reported Outcome Expectations of Non-invasive Brain Stimulation Are Malleable: a Registered Report that Replicates and Extends Rabipour et al. (2017). JOURNAL OF COGNITIVE ENHANCEMENT 2022. [DOI: 10.1007/s41465-022-00250-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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30
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Gordon MS, Seeto JXW, Dux PE, Filmer HL. Intervention is a better predictor of tDCS mind-wandering effects than subjective beliefs about experimental results. Sci Rep 2022; 12:13110. [PMID: 35908042 PMCID: PMC9338927 DOI: 10.1038/s41598-022-16545-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 07/12/2022] [Indexed: 11/29/2022] Open
Abstract
Blinding in non-invasive brain stimulation research is a topic of intense debate, especially regarding the efficacy of sham-controlled methods for transcranial direct current stimulation (tDCS). A common approach to assess blinding success is the inclusion of correct guess rate. However, this method cannot provide insight into the effect of unblinding on observed stimulation outcomes. Thus, the implementation of measures to systematically evaluate subjective expectation regarding stimulation is needed. Previous work evaluated subjective effects in an earlier study which reported a mind-wandering and tDCS data set and concluded that subjective belief drove the pattern of results observed. Here we consider the subjective and objective intervention effects in a key contrast from that data set-2 mA vs. sham-which was not examined in the reanalysis. In addition, we examine another key contrast from a different tDCS mind-wandering study that employed similar methodology. Our findings support objective intervention as the strongest predictor of the observed effects of mind-wandering in both re-analyses, over and above that of subjective intervention. However, it is important to control for and understand the possible inadequacies of sham-controlled methods.
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Affiliation(s)
- Matilda S Gordon
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia.
| | - Jennifer X W Seeto
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
| | - Paul E Dux
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
| | - Hannah L Filmer
- School of Psychology, The University of Queensland, McElwain Building (24A), St Lucia, QLD, 4072, Australia
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31
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Caulfield KA, Indahlastari A, Nissim NR, Lopez JW, Fleischmann HH, Woods AJ, George MS. Electric Field Strength From Prefrontal Transcranial Direct Current Stimulation Determines Degree of Working Memory Response: A Potential Application of Reverse-Calculation Modeling? Neuromodulation 2022; 25:578-587. [PMID: 35670064 DOI: 10.1111/ner.13342] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/24/2020] [Accepted: 11/30/2020] [Indexed: 12/26/2022]
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) for working memory is an enticing treatment, but there is mixed evidence to date. OBJECTIVES We tested the effects of electric field strength from uniform 2 mA dosing on working memory change from prestimulation to poststimulation. Second, we statistically evaluated a reverse-calculation method of individualizing tDCS dose and its effect on normalizing electric field at the cortex. MATERIALS AND METHODS We performed electric field modeling on a data set of 28 healthy older adults (15 women, mean age = 73.7, SD = 7.3) who received ten sessions of active 2 mA tDCS (N = 14) or sham tDCS (N = 14) applied over bilateral dorsolateral prefrontal cortices (DLPFC) in a triple-blind design. We evaluated the relationship between electric field strength and working memory change on an N-back task in conditions of above-median, high electric field from active 2 mA (N = 7), below-median, low electric field from active 2 mA (N = 7), and sham (N = 14) at regions of interest (ROI) at the left and right DLPFC. We then determined the individualized reverse-calculation dose to produce the group average electric field and measured the electric field variance between uniform 2 mA doses vs individualized reverse-calculation doses at the same ROIs. RESULTS Working memory improvements from pre- to post-tDCS were significant for the above-median electric field from active 2 mA condition at the left DLPFC (mixed ANOVA, p = 0.013). Furthermore, reverse-calculation modeling significantly reduced electric field variance at both ROIs (Levene's test; p < 0.001). CONCLUSIONS Higher electric fields at the left DLPFC from uniform 2 mA doses appear to drive working memory improvements from tDCS. Individualized doses from reverse-calculation modeling significantly reduce electric field variance at the cortex. Taken together, using reverse-calculation modeling to produce the same, high electric fields at the cortex across participants may produce more effective future tDCS treatments for working memory.
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Affiliation(s)
- Kevin A Caulfield
- Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA.
| | - Aprinda Indahlastari
- Center for Cognitive Aging and Memory Clinical Translational Research, McKnight Brain Institute, Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA
| | - Nicole R Nissim
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - James W Lopez
- Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA
| | - Holly H Fleischmann
- Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA
| | - Adam J Woods
- Center for Cognitive Aging and Memory Clinical Translational Research, McKnight Brain Institute, Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA
| | - Mark S George
- Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, Charleston, SC, USA; Ralph H. Johnson VA Medical Center, Charleston, SC, USA
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32
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Vergallito A, Feroldi S, Pisoni A, Romero Lauro LJ. Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors. Brain Sci 2022; 12:522. [PMID: 35624908 PMCID: PMC9139102 DOI: 10.3390/brainsci12050522] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/08/2022] [Accepted: 04/14/2022] [Indexed: 01/27/2023] Open
Abstract
Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS's wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS's ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half-or less-of studies' participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments' contextual elements, such as participants' engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols' efficiency and reproducibility.
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Affiliation(s)
- Alessandra Vergallito
- Department of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, Italy; (A.P.); (L.J.R.L.)
| | - Sarah Feroldi
- School of Medicine and Surgery, University of Milano-Bicocca, 20854 Monza, Italy;
| | - Alberto Pisoni
- Department of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, Italy; (A.P.); (L.J.R.L.)
| | - Leonor J. Romero Lauro
- Department of Psychology & NeuroMi, University of Milano Bicocca, 20126 Milano, Italy; (A.P.); (L.J.R.L.)
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33
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Johnson EL, Arciniega H, Jones KT, Kilgore-Gomez A, Berryhill ME. Individual predictors and electrophysiological signatures of working memory enhancement in aging. Neuroimage 2022; 250:118939. [PMID: 35104647 PMCID: PMC8923157 DOI: 10.1016/j.neuroimage.2022.118939] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 01/25/2022] [Indexed: 12/21/2022] Open
Abstract
A primary goal of translational neuroscience is to identify the neural mechanisms of age-related cognitive decline and develop protocols to maximally improve cognition. Here, we demonstrate how interventions that apply noninvasive neurostimulation to older adults improve working memory (WM). We found that one session of sham-controlled transcranial direct current stimulation (tDCS) selectively improved WM in older adults with more education, extending earlier work and underscoring the importance of identifying individual predictors of tDCS responsivity. Improvements in WM were associated with two distinct electrophysiological signatures. First, a broad enhancement of theta network synchrony tracked improvements in behavioral accuracy, with tDCS effects moderated by education level. Further analysis revealed that accuracy dynamics reflected an anterior-posterior network distribution regardless of cathode placement. Second, specific enhancements of theta-gamma phase-amplitude coupling (PAC) reflecting tDCS current flow tracked improvements in reaction time (RT). RT dynamics further explained inter-individual variability in WM improvement independent of education. These findings illuminate theta network synchrony and theta-gamma PAC as distinct but complementary mechanisms supporting WM in aging. Both mechanisms are amenable to intervention, the effectiveness of which can be predicted by individual demographic factors.
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Affiliation(s)
- Elizabeth L Johnson
- Departments of Medical Social Sciences and Pediatrics, Northwestern University, Chicago, IL, 60611, United States.
| | - Hector Arciniega
- Psychiatry Neuroimaging Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02215, United States
| | - Kevin T Jones
- Department of Neurology, Neuroscape, University of California-San Francisco, San Francisco, CA, 94158, United States
| | - Alexandrea Kilgore-Gomez
- Department of Psychology, Program in Cognitive and Brain Sciences, Program in Integrative Neuroscience, University of Nevada, Reno, 89557, United States
| | - Marian E Berryhill
- Department of Psychology, Program in Cognitive and Brain Sciences, Program in Integrative Neuroscience, University of Nevada, Reno, 89557, United States.
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34
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Mind-wandering: mechanistic insights from lesion, tDCS, and iEEG. Trends Cogn Sci 2022; 26:268-282. [PMID: 35086725 PMCID: PMC9166901 DOI: 10.1016/j.tics.2021.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/04/2023]
Abstract
Cognitive neuroscience has witnessed a surge of interest in investigating the neural correlates of the mind when it drifts away from an ongoing task and the external environment. To that end, functional neuroimaging research has consistently implicated the default mode network (DMN) and frontoparietal control network (FPCN) in mind-wandering. Yet, it remains unknown which subregions within these networks are necessary and how they facilitate mind-wandering. In this review, we synthesize evidence from lesion, transcranial direct current stimulation (tDCS), and intracranial electroencephalogram (iEEG) studies demonstrating the causal relevance of brain regions, and providing insights into the neuronal mechanism underlying mind-wandering. We propose that the integration of complementary approaches is the optimal strategy to establish a comprehensive understanding of the neural basis of mind-wandering.
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35
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No effects of transcranial direct current stimulation on visual evoked potential and peak gamma frequency. Cogn Process 2022; 23:235-254. [PMID: 35099659 DOI: 10.1007/s10339-022-01076-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 01/12/2022] [Indexed: 11/03/2022]
Abstract
Evidence suggests that the visual evoked potential (VEP) and gamma oscillations elicited by visual stimuli reflect the balance of excitatory and inhibitory (E-I) cortical processes. As tDCS has been shown to modulate E-I balance, the current study investigated whether amplitudes of VEP components (N1 and P2) and peak gamma frequency are modulated by transcranial direct current stimulation (tDCS). Healthy adults underwent two electroencephalography (EEG) recordings while viewing stimuli designed to elicit a robust visual response. Between the two recordings, participants were randomly assigned to three tDCS conditions (anodal-, cathodal-, and sham-tDCS) or received no-tDCS. tDCS electrodes were placed over the occipital cortex (Oz) and the left cheek with an intensity of 2 mA for 10 min. Data of 39 participants were analysed for VEP amplitudes and peak gamma frequency using mixed-model ANOVAs. The results showed no main effects of tDCS in any metric. Possible explanations for the absence of tDCS effects are discussed.
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36
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Reteig LC, Newman LA, Ridderinkhof KR, Slagter HA. Effects of tDCS on the attentional blink revisited: A statistical evaluation of a replication attempt. PLoS One 2022; 17:e0262718. [PMID: 35085301 PMCID: PMC8794161 DOI: 10.1371/journal.pone.0262718] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 12/31/2021] [Indexed: 11/19/2022] Open
Abstract
The attentional blink (AB) phenomenon reveals a bottleneck of human information processing: the second of two targets is often missed when they are presented in rapid succession among distractors. In our previous work, we showed that the size of the AB can be changed by applying transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (lDLPFC) (London & Slagter, Journal of Cognitive Neuroscience, 33, 756-68, 2021). Although AB size at the group level remained unchanged, the effects of anodal and cathodal tDCS were negatively correlated: if a given individual's AB size decreased from baseline during anodal tDCS, their AB size would increase during cathodal tDCS, and vice versa. Here, we attempted to replicate this finding. We found no group effects of tDCS, as in the original study, but we no longer found a significant negative correlation. We present a series of statistical measures of replication success, all of which confirm that both studies are not in agreement. First, the correlation here is significantly smaller than a conservative estimate of the original correlation. Second, the difference between the correlations is greater than expected due to sampling error, and our data are more consistent with a zero-effect than with the original estimate. Finally, the overall effect when combining both studies is small and not significant. Our findings thus indicate that the effects of lDPLFC-tDCS on the AB are less substantial than observed in our initial study. Although this should be quite a common scenario, null findings can be difficult to interpret and are still under-represented in the brain stimulation and cognitive neuroscience literatures. An important auxiliary goal of this paper is therefore to provide a tutorial for other researchers, to maximize the evidential value from null findings.
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Affiliation(s)
- Leon C. Reteig
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, The Netherlands
| | - Lionel A. Newman
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
- Department of Artificial Intelligence and Cognitive Engineering, University of Groningen, Groningen, The Netherlands
| | - K. Richard Ridderinkhof
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, The Netherlands
| | - Heleen A. Slagter
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
- Department of Applied and Experimental Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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37
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Sun JB, Cheng C, Tian QQ, Yuan H, Yang XJ, Deng H, Guo XY, Cui YP, Zhang MK, Yin ZX, Wang C, Qin W. Transcutaneous Auricular Vagus Nerve Stimulation Improves Spatial Working Memory in Healthy Young Adults. Front Neurosci 2022; 15:790793. [PMID: 35002607 PMCID: PMC8733384 DOI: 10.3389/fnins.2021.790793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/18/2021] [Indexed: 01/08/2023] Open
Abstract
Working memory (WM) is one of the core components of higher cognitive functions. There exists debate regarding the extent to which current techniques can enhance human WM capacity. Here, we examined the WM modulation effects of a previously less studied technique, transcutaneous auricular vagus nerve stimulation (taVNS). In experiment 1, a within-subject study, we aimed to investigate whether and which stimulation protocols of taVNS can modulate spatial WM performance in healthy adults. Forty-eight participants performed baseline spatial n-back tasks (1, 3-back) and then received online taVNS, offline taVNS, or sham stimulation before or during (online group) the posttest of spatial n-back tasks in random order. Results showed that offline taVNS could significantly increase hits in spatial 3-back task, whereas no effect was found in online taVNS or sham group. No significant taVNS effects were found on correct rejections or reaction time of accurate trials (aRT) in both online and offline protocols. To replicate the results found in experiment 1 and further investigate the generalization effect of offline taVNS, we carried out experiment 2. Sixty participants were recruited and received offline taVNS or offline earlobe stimulation in random order between baseline and posttests of behavioral tests (spatial/digit 3-back tasks). Results replicated the findings; offline taVNS could improve hits but not correct rejections or aRT in spatial WM performance, which were found in experiment 1. However, there were no significant stimulation effects on digit 3-back task. Overall, the findings suggest that offline taVNS has potential on modulating WM performance.
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Affiliation(s)
- Jin-Bo Sun
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China.,Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Chen Cheng
- Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Qian-Qian Tian
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China
| | - Hang Yuan
- Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Xue-Juan Yang
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China.,Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Hui Deng
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China.,Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Xiao-Yu Guo
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China
| | - Ya-Peng Cui
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China
| | - Meng-Kai Zhang
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China
| | - Zi-Xin Yin
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China
| | - Cong Wang
- Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
| | - Wei Qin
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Sciences and Technology, Xidian University, Xi'an, China.,Intelligent Non-invasive Neuromodulation Technology and Transformation Joint Laboratory, Xidian University, Xi'an, China
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38
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Esposito M, Ferrari C, Fracassi C, Miniussi C, Brignani D. Responsiveness to left-prefrontal tDCS varies according to arousal levels. Eur J Neurosci 2022; 55:762-777. [PMID: 34978110 PMCID: PMC9302688 DOI: 10.1111/ejn.15584] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 12/03/2021] [Accepted: 12/21/2021] [Indexed: 12/01/2022]
Abstract
Over the past two decades, the postulated modulatory effects of transcranial direct current stimulation (tDCS) on the human brain have been extensively investigated. However, recent concerns on reliability of tDCS effects have been raised, principally due to reduced replicability and to interindividual variability in response to tDCS. These inconsistencies are likely due to the interplay between the level of induced cortical excitability and unaccounted structural and state‐dependent functional factors. On these grounds, we aimed at verifying whether the behavioural effects induced by a common tDCS montage (F3‐rSOA) were influenced by the participants' arousal levels, as part of a broader mechanism of state‐dependency. Pupillary dynamics were recorded during an auditory oddball task while applying either a sham or real tDCS. The tDCS effects were evaluated as a function of subjective and physiological arousal predictors (STAI‐Y State scores and pre‐stimulus pupil size, respectively). We showed that prefrontal tDCS hindered task learning effects on response speed such that performance improvement occurred during sham, but not real stimulation. Moreover, both subjective and physiological arousal predictors significantly explained performance during real tDCS, with interaction effects showing performance improvement only with moderate arousal levels; likewise, pupil response was affected by real tDCS according to the ongoing levels of arousal, with reduced dilation during higher arousal trials. These findings highlight the potential role of arousal in shaping the neuromodulatory outcome, thus emphasizing a more careful interpretation of null or negative results while also encouraging more individually tailored tDCS applications based on arousal levels, especially in clinical populations.
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Affiliation(s)
- Marco Esposito
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Clarissa Ferrari
- Unit of Statistics, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Claudia Fracassi
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Carlo Miniussi
- Center for Mind/Brain Sciences CIMeC, University of Trento, Rovereto, Italy
| | - Debora Brignani
- Neurophysiology Lab, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
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39
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Stanković M, Živanović M, Bjekić J, Filipović SR. Blinding in tDCS Studies: Correct End-of-Study Guess Does Not Moderate the Effects on Associative and Working Memory. Brain Sci 2021; 12:brainsci12010058. [PMID: 35053802 PMCID: PMC8773753 DOI: 10.3390/brainsci12010058] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 11/16/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has become a valuable tool in cognitive neuroscience research as it enables causal inferences about neural underpinnings of cognition. However, studies using tDCS to modulate cognitive functions often yield inconsistent findings. Hence, there is an increasing interest in factors that may moderate the effects, one of which is the participants’ beliefs of the tDCS condition (i.e., real or sham) they received. Namely, whether participants’ correct guessing of sham condition may lead to false-positive tDCS effects. In this study, we aimed to explore if participants’ beliefs about received stimulation type (i.e., the success of blinding) impacted their task performance in tDCS experiments on associative (AM) and working memory (WM). We analyzed data from four within-subject, sham-controlled tDCS memory experiments (N = 83) to check if the correct end-of-study guess of sham condition moderated tDCS effects. We found no evidence that sham guessing moderated post-tDCS memory performance in experiments in which tDCS effects were observed as well as in experiments that showed null effects of tDCS. The results suggest that the correct sham guessing (i.e., placebo-like effect) is unlikely to influence the results in tDCS memory experiments. We discuss the results in light of the growing debate about the relevance and effectiveness of blinding in brain stimulation research.
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Affiliation(s)
- Marija Stanković
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
| | - Marko Živanović
- Institute of Psychology and Laboratory for Research of Individual Differences, Department of Psychology, Faculty of Philosophy, University of Belgrade, 11000 Belgrade, Serbia;
| | - Jovana Bjekić
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
- Correspondence:
| | - Saša R. Filipović
- Human Neuroscience Group, Institute for Medical Research, University of Belgrade, 11000 Belgrade, Serbia; (M.S.); (S.R.F.)
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Xu Y, Chen S, Kong Q, Luo S. The residential stability mindset increases racial in-group bias in empathy. Biol Psychol 2021; 165:108194. [PMID: 34560174 DOI: 10.1016/j.biopsycho.2021.108194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 09/03/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022]
Abstract
With the deepening of internationalization, the population's mobility has greatly increased, which can impact people's intergroup relationships. The current research examined the hypothesis that residential mobility plays a crucial role in racial in-group bias in empathy (RIBE) with three studies. By manipulating the residential mobility/stability mindset and measuring subjective pain intensity ratings (Study 1) and event-related potentials (ERPs, Study 2) of Chinese adults on painful and neutral expressions of Asian and Caucasian faces, we found that the RIBE in subjective ratings and N1 amplitudes increased and P3 amplitudes decreased in the stability group. Transcranial direct current stimulation (tDCS) manipulation in Study 3 further found that anodal stimulation of the left dorsolateral prefrontal cortex (DLPFC) increased the RIBE of participants with residential stability experience but had no effect on those with residential mobility experience. As residential mobility continues to increase worldwide, we may observe concomitant changes in racial intergroup relationships.
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Affiliation(s)
- Ying Xu
- Department of Psychology, Guangdong Provincial Key Laboratory of Social Cognitive Neuroscience and Mental Health, Guangdong Provincial Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, Guangzhou 510006, China
| | - Shangyi Chen
- Department of Psychology, Guangdong Provincial Key Laboratory of Social Cognitive Neuroscience and Mental Health, Guangdong Provincial Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, Guangzhou 510006, China
| | - Qianting Kong
- Department of Psychology, Guangdong Provincial Key Laboratory of Social Cognitive Neuroscience and Mental Health, Guangdong Provincial Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, Guangzhou 510006, China
| | - Siyang Luo
- Department of Psychology, Guangdong Provincial Key Laboratory of Social Cognitive Neuroscience and Mental Health, Guangdong Provincial Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, Guangzhou 510006, China.
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41
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Bolling AJ, King VL, Enam T, McDonough IM. Using transcranial direct current stimulation (tDCS) on the dorsolateral prefrontal cortex to promote long-term foreign language vocabulary learning. Brain Cogn 2021; 154:105789. [PMID: 34509124 DOI: 10.1016/j.bandc.2021.105789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 08/22/2021] [Accepted: 08/27/2021] [Indexed: 11/26/2022]
Abstract
Transcranial direct current stimulation (tDCS) on the dorsolateral prefrontal cortex (DLPFC) was used to improve foreign-langue learning while using mental imagery. Participants underwent two sessions of 1 mA, 1.5 mA, or sham stimulation prior to learning Swahili-English word pairs two consecutive days. During learning, participants were encouraged to create a mental image of the associated English word. Twenty-four hours after learning and one week later, participants received a cued recall test. A linear dose-response effect of stimulation was found across both tests that occurred long after the immediate effects of stimulation. Follow-up comparisons revealed that only the 1.5 mA condition differed from the sham group. Exploratory moderating effects revealed interactions with sleep quality and handedness. Those with poorer sleep and who were left-handed showed greater recall after 1.5 mA of stimulation than those with better sleep and right-handers. A follow-up behavioral study probing strategy usage indicated that mental imagery strategy use did not strongly impact learning but point to other possible mechanisms including the importance of attending to multimodal perceptual details and memory consolidation. This preliminary evidence supports the role of the DLPFC or connected regions in foreign language vocabulary learning and verbal memory encoding.
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Affiliation(s)
- A Jordan Bolling
- Department of Psychology, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Victoria L King
- Department of Psychology, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Tasnuva Enam
- Department of Psychology, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Ian M McDonough
- Department of Psychology, The University of Alabama, Tuscaloosa, AL 35487, USA.
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42
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Zanto TP, Jones KT, Ostrand AE, Hsu WY, Campusano R, Gazzaley A. Individual differences in neuroanatomy and neurophysiology predict effects of transcranial alternating current stimulation. Brain Stimul 2021; 14:1317-1329. [PMID: 34481095 DOI: 10.1016/j.brs.2021.08.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 08/11/2021] [Accepted: 08/19/2021] [Indexed: 10/20/2022] Open
Abstract
BACKGROUND Noninvasive transcranial electrical stimulation (tES) research has been plagued with inconsistent effects. Recent work has suggested neuroanatomical and neurophysiological variability may alter tES efficacy. However, direct evidence is limited. OBJECTIVE We have previously replicated effects of transcranial alternating current stimulation (tACS) on improving multitasking ability in young adults. Here, we attempt to assess whether these stimulation parameters have comparable effects in older adults (aged 60-80 years), which is a population known to have greater variability in neuroanatomy and neurophysiology. It is hypothesized that this variability in neuroanatomy and neurophysiology will be predictive of tACS efficacy. METHODS We conducted a pre-registered study where tACS was applied above the prefrontal cortex (between electrodes F3-F4) while participants were engaged in multitasking. Participants were randomized to receive either 6-Hz (theta) tACS for 26.67 min daily for three days (80 min total; Long Exposure Theta group), 6-Hz tACS for 5.33 min daily (16-min total; Short Exposure Theta group), or 1-Hz tACS for 26.67 min (80 min total; Control group). To account for neuroanatomy, magnetic resonance imaging data was used to form individualized models of the tACS-induced electric field (EF) within the brain. To account for neurophysiology, electroencephalography data was used to identify individual peak theta frequency. RESULTS Results indicated that only in the Long Theta group, performance change was correlated with modeled EF and peak theta frequency. Together, modeled EF and peak theta frequency accounted for 54%-65% of the variance in tACS-related performance improvements, which sustained for a month. CONCLUSION These results demonstrate the importance of individual differences in neuroanatomy and neurophysiology in tACS research and help account for inconsistent effects across studies.
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Affiliation(s)
- Theodore P Zanto
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA; Neuroscape, University of California-San Francisco, San Francisco, CA, USA.
| | - Kevin T Jones
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA; Neuroscape, University of California-San Francisco, San Francisco, CA, USA
| | - Avery E Ostrand
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA; Neuroscape, University of California-San Francisco, San Francisco, CA, USA
| | - Wan-Yu Hsu
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA
| | - Richard Campusano
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA; Neuroscape, University of California-San Francisco, San Francisco, CA, USA
| | - Adam Gazzaley
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA; Neuroscape, University of California-San Francisco, San Francisco, CA, USA; Departments of Physiology and Psychiatry, University of California-San Francisco, San Francisco, CA, USA
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43
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Kim J, Kim H, Jeong H, Roh D, Kim DH. tACS as a promising therapeutic option for improving cognitive function in mild cognitive impairment: A direct comparison between tACS and tDCS. J Psychiatr Res 2021; 141:248-256. [PMID: 34256276 DOI: 10.1016/j.jpsychires.2021.07.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/17/2021] [Accepted: 07/05/2021] [Indexed: 02/07/2023]
Abstract
Neuromodulation has gained attention as a potential non-pharmacological intervention for mild cognitive impairment (MCI). However, no studies have directly compared the effects of transcranial alternating current stimulation (tACS) with transcranial direct current stimulation (tDCS) on MCI patients. We aimed to identify the more promising and efficient therapeutic option between tACS and tDCS for cognitive enhancement in MCI patients. We compared the effects of gamma-tACS with tDCS on cognitive function and electroencephalography (EEG) in MCI patients. In this sham-controlled, double-blinded, repeated-measures study with the order of the stimulation counterbalanced across patients (n = 20), both gamma-tACS (40 H z) and tDCS were administered at the same intensity (2 mA) in the dorsolateral prefrontal cortex for 30 min. Cognitive tests (Stroop and Trail-Making-Test [TMT]) and EEG were performed before and after single-session stimulation. Gamma-tACS improved the Stroop-color in comparison with tDCS (p = .044) and sham (p = .010) and enhanced the TMT-B in comparison with sham (p = .021). However, tDCS was not significantly different from sham in changes of any cognitive test scores. In EEG analysis, gamma-tACS increased beta activity in comparison with sham and tDCS, whereas tDCS decreased delta and theta activity in comparison with sham. Gamma-tACS also increased beta 2 source activity in the anterior cingulate, compared to sham. The cognitive benefits of tACS in MCI patients appeared superior to those of tDCS. tACS facilitated cognitive function by increasing beta activity, while tDCS delayed the progression of MCI symptoms by decreasing slow-frequency activity. Thus, tACS could be used as a new therapeutic option for MCI.
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Affiliation(s)
- Jiheon Kim
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea; Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Hansol Kim
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Hyewon Jeong
- Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Daeyoung Roh
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea; Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea
| | - Do Hoon Kim
- Department of Psychiatry, Chuncheon Sacred Heart Hospital, Chuncheon, Republic of Korea; Mind-Neuromodulation Laboratory, College of Medicine, Hallym University, Chuncheon, Republic of Korea.
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44
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Balboa-Bandeira Y, Zubiaurre-Elorza L, Ibarretxe-Bilbao N, Ojeda N, Peña J. Effects of transcranial electrical stimulation techniques on second and foreign language learning enhancement in healthy adults: A systematic review and meta-analysis. Neuropsychologia 2021; 160:107985. [PMID: 34371068 DOI: 10.1016/j.neuropsychologia.2021.107985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/26/2021] [Accepted: 08/02/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Transcranial electrical stimulation (tES) techniques have been used to enhance different cognitive domains such as language in healthy adults. While several reviews and meta-analysis have been conducted on the effects of tES on different language skills (picture naming, verbal fluency, word reading), there has been little research conducted to date on the effects of tES on the processes involved in foreign language learning. OBJECTIVE A meta-analysis was performed to quantify the effects of tES on foreign language learning processes (non-words, artificial grammar, and foreign languages), focusing on accuracy, response times and 1-week follow-up effects, if reported by the studies. RESULTS Eleven studies that had sham condition were reviewed. Nine of them were analyzed, including five using within-participant design, and four that employed between-participant design. The final analysis encompassed nine studies with 279 healthy participants. The analysis showed moderate enhancing effects of tES on overall language learning (g = 0.50, 95 % CI [0.29, 0.71], p = .0001). However, results were not significant on follow up data (g = 0.54, 95 % CI [-0.12, 1.20], p = .07), and on response times (g = 0.50, 95 % CI [-0.1, 1.18], p = .10). The effects were significantly moderated by years of education. CONCLUSIONS The results suggest that tES seems to enhance the mechanisms involved in foreign language learning; however, more research is needed to understand the impact scope of these techniques on language learning processes.
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Affiliation(s)
| | | | | | - Natalia Ojeda
- Department of Methods and Experimental Psychology, University of Deusto, Bilbao, Spain
| | - Javier Peña
- Department of Methods and Experimental Psychology, University of Deusto, Bilbao, Spain.
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45
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Johnson EL, Jones KT. Longitudinal indices of human cognition and brain structure. J Neurosci Res 2021; 99:2323-2326. [PMID: 34328671 DOI: 10.1002/jnr.24938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/14/2021] [Indexed: 11/08/2022]
Affiliation(s)
- Elizabeth L Johnson
- Helen Wills Neuroscience Institute, University of California-Berkeley, Berkeley, CA, USA.,Institute of Gerontology, Life-Span Cognitive Neuroscience Program, Wayne State University, Detroit, MI, USA
| | - Kevin T Jones
- Department of Neurology, University of California-San Francisco, San Francisco, CA, USA.,Neuroscape, University of California-San Francisco, San Francisco, CA, USA
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46
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Transcranial Direct Current Stimulation (tDCS) over the Intraparietal Sulcus Does Not Influence Working Memory Performance. Psychol Belg 2021; 61:200-211. [PMID: 34277028 PMCID: PMC8269793 DOI: 10.5334/pb.534] [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: 01/09/2020] [Accepted: 06/15/2021] [Indexed: 02/06/2023] Open
Abstract
Mixed results of the impact of transcranial direct current stimulation (tDCS) on working memory have been reported. Contrarily to previous studies who focused mainly on stimulating the dorsolateral prefrontal cortex, we modulated the left intraparietal sulcus (IPS) area which is considered to support attentional control aspects of working memory. Using a within-participant experimental design, participants completed three different conditions: anodal stimulation of the IPS, cathodal stimulation of the IPS, and sham stimulation of the IPS. Both visual and verbal working memory tasks were administered. In the visual task, participants had to memorize a random set of colored figures. In the verbal task, participants had to memorize a string of letters. Working memory load was manipulated in both tasks (six figures/letters vs. two figures/letters). No significant differences in accuracy or reaction time between the anodal, cathodal and sham conditions were found. Bayesian analysis supported evidence for an absence of effect. The results of the present study add to the growing body of contradictory evidence regarding the modulatory effects of single session tDCS on working memory performance.
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47
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Nousia A, Martzoukou M, Liampas I, Siokas V, Bakirtzis C, Nasios G, Dardiotis E. The Effectiveness of Non-Invasive Brain Stimulation Alone or Combined with Cognitive Training on the Cognitive Performance of Patients With Traumatic Brain Injury: Α Systematic Review. Arch Clin Neuropsychol 2021; 37:497-512. [PMID: 34155517 DOI: 10.1093/arclin/acab047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE The present study reviewed published evidence on the effectiveness of non-invasive brain stimulation (NIBS) on the cognitive performance of patients with Traumatic brain injury (TBI). METHOD A systematic search of the PubMed and Google Scholar databases was carried out. Randomized Controlled Studies published before March 2020 were included. Methodological evaluation was performed based on the Risk of Bias Cochrane tool. A total of 10 placebo-controlled studies fulfilled the inclusion criteria and were involved in the qualitative analysis, two assessing NIBS combined with cognitive training (CT) and eight evaluating NIBS alone. RESULTS All but one retrieved article were appraised as of high-risk of bias (one paper was assessed as of unclear-risk owing to considerable underreporting). With the potential exception of attention, our findings were not indicative of a superior efficacy of NIBS-CT to CT alone, regarding the improvement of any of the rest assessed cognitive deficits. Executive function, processing speed, attention, working, and visuospatial memory were only occasionally found to benefit from NIBS alone compared to sham therapy (only one study reported relevant benefits per neuropsychological outcome). Verbal memory and verbal fluency (phonemic-semantic) were consistently found not to benefit from NIBS. Depression measures were the only outcomes associated with a beneficial effect of NIBS in more than one article. CONCLUSION Our findings did not provide sufficient high-quality evidence to support the exclusive use of NIBS or combined NIBS-CT to improve any impaired cognitive function in TBI patients. Owing to the suboptimum methodological quality of published studies, additional research is of potential value.
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Affiliation(s)
- Anastasia Nousia
- Department of Speech and Language Therapy, University of Ioannina, Ioannina, Greece
| | - Maria Martzoukou
- Department of Speech and Language Therapy, University of Ioannina, Ioannina, Greece
| | - Ioannis Liampas
- Department of Neurology, University Hospital of Larissa, Greece.,Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Vasileios Siokas
- Department of Neurology, University Hospital of Larissa, Greece.,Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Christos Bakirtzis
- B' Department of Neurology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Grigorios Nasios
- Department of Speech and Language Therapy, University of Ioannina, Ioannina, Greece
| | - Efthimios Dardiotis
- Department of Neurology, University Hospital of Larissa, Greece.,Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
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48
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Zhu R, Luo Y, Wang Z, You X. Within-session repeated transcranial direct current stimulation of the posterior parietal cortex enhances spatial working memory. Cogn Neurosci 2021; 13:26-37. [PMID: 33739230 DOI: 10.1080/17588928.2021.1877648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Spatial working memory (SWM) is an essential cognitive ability that supports complex tasks, but its capacity is limited. Studies using transcranial direct current stimulation (tDCS) have shown potential benefits for SWM performance. Recent studies have shown that repeated short applications of tDCS affected corticospinal excitability. Moreover, neuroimaging studies have indicated that the pattern of neural activity measured in the posterior parietal cortex (PPC) tracks SWM ability. It is unknown whether repeated tDCS can enhance SWM and whether varied tDCS protocols (single 10 min tDCS, 10 min tDCS-5 min break-10 min tDCS, 10 min tDCS-20 min break-10 min tDCS) over the right PPC have different effects on SWM. The current study investigated whether offline single-session and repeated tDCS over the right PPC affects SWM updating, as measured by spatial 2-back and 3-back tasks. The results showed that stimulating the right PPC with repeated 10 min anodal tDCS significantly improved the response speed of the spatial 2-back task relative to single-session tDCS. Repeated 10 min tDCS with a longer interval (i.e. inter-stimulation interval of 20 min) enhanced the response speed of the spatial 3-back task. Altogether these findings provide causal evidence that suggests that the right PPC plays an important role in SWM. Furthermore, repeated tDCS with longer intervals may be a promising intervention for improving SWM-related function.
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Affiliation(s)
- Rongjuan Zhu
- Key Laboratory for Behavior and Cognitive Neuroscience of Shaanxi Province, School of Psychology, Shaanxi Normal University, Xi'an, China
| | - Yangmei Luo
- Key Laboratory for Behavior and Cognitive Neuroscience of Shaanxi Province, School of Psychology, Shaanxi Normal University, Xi'an, China
| | - Ziyu Wang
- Key Laboratory for Behavior and Cognitive Neuroscience of Shaanxi Province, School of Psychology, Shaanxi Normal University, Xi'an, China
| | - Xuqun You
- Key Laboratory for Behavior and Cognitive Neuroscience of Shaanxi Province, School of Psychology, Shaanxi Normal University, Xi'an, China
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49
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Assecondi S, Hu R, Eskes G, Pan X, Zhou J, Shapiro K. Impact of tDCS on working memory training is enhanced by strategy instructions in individuals with low working memory capacity. Sci Rep 2021; 11:5531. [PMID: 33750803 PMCID: PMC7943602 DOI: 10.1038/s41598-021-84298-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 02/09/2021] [Indexed: 11/09/2022] Open
Abstract
Interventions to improve working memory, e.g. by combining task rehearsal and non-invasive brain stimulation, are gaining popularity. Many factors, however, affect the outcome of these interventions. We hypothesize that working memory capacity at baseline predicts how an individual performs on a working memory task, by setting limits on the benefit derived from tDCS when combined with strategy instructions; specifically, we hypothesize that individuals with low capacity will benefit the most. Eighty-four participants underwent two sessions of an adaptive working memory task (n-back) on two consecutive days. Participants were split into four independent groups (SHAM vs ACTIVE stimulation and STRATEGY vs no STRATEGY instructions). For the purpose of analysis, individuals were divided based on their baseline working memory capacity. Results support our prediction that the combination of tDCS and strategy instructions is particularly beneficial in low capacity individuals. Our findings contribute to a better understanding of factors affecting the outcome of tDCS when used in conjunction with cognitive training to improve working memory. Moreover, our results have implications for training regimens, e.g., by designing interventions predicated on baseline cognitive abilities, or focusing on strategy development for specific attentional skills.
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Affiliation(s)
- Sara Assecondi
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, UK. .,Center for Human Brain Health (CHBH), University of Birmingham, Birmingham, UK.
| | - Rong Hu
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, UK.,Center for Human Brain Health (CHBH), University of Birmingham, Birmingham, UK.,Department of Neurology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Gail Eskes
- Departments of Psychiatry and Psychology & Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Xiaoping Pan
- Department of Neurology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Jin Zhou
- Department of Neurology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Kim Shapiro
- Visual Experience Laboratory, School of Psychology, University of Birmingham, Birmingham, UK.,Center for Human Brain Health (CHBH), University of Birmingham, Birmingham, UK
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50
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Kolskår KK, Richard G, Alnæs D, Dørum ES, Sanders A, Ulrichsen KM, Sánchez JM, Ihle‐Hansen H, Nordvik JE, Westlye LT. Reliability, sensitivity, and predictive value of fMRI during multiple object tracking as a marker of cognitive training gain in combination with tDCS in stroke survivors. Hum Brain Mapp 2021; 42:1167-1181. [PMID: 33216408 PMCID: PMC7856645 DOI: 10.1002/hbm.25284] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 10/21/2020] [Accepted: 10/27/2020] [Indexed: 11/23/2022] Open
Abstract
Computerized cognitive training (CCT) combined with transcranial direct current stimulation (tDCS) has showed some promise in alleviating cognitive impairments in patients with brain disorders, but the robustness and possible mechanisms are unclear. In this prospective double-blind randomized clinical trial, we investigated the feasibility and effectiveness of combining CCT and tDCS, and tested the predictive value of and training-related changes in fMRI-based brain activation during attentive performance (multiple object tracking) obtained at inclusion, before initiating training, and after the three-weeks intervention in chronic stroke patients (>6 months since hospital admission). Patients were randomized to one of two groups, receiving CCT and either (a) tDCS targeting left dorsolateral prefrontal cortex (1 mA), or (b) sham tDCS, with 40s active stimulation (1 mA) before fade out of the current. Of note, 77 patients were enrolled in the study, 54 completed the cognitive training, and 48 completed all training and MRI sessions. We found significant improvement in performance across all trained tasks, but no additional gain of tDCS. fMRI-based brain activation showed high reliability, and higher cognitive performance was associated with increased tracking-related activation in the dorsal attention network and default mode network as well as anterior cingulate after compared to before the intervention. We found no significant associations between cognitive gain and brain activation measured before training or in the difference in activation after intervention. Combined, these results show significant training effects on trained cognitive tasks in stroke survivors, with no clear evidence of additional gain of concurrent tDCS.
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Affiliation(s)
- Knut K. Kolskår
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Sunnaas Rehabilitation Hospital HTNesoddenNorway
- Department of PsychologyUniversity of OsloOsloNorway
| | - Geneviève Richard
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Sunnaas Rehabilitation Hospital HTNesoddenNorway
- Department of PsychologyUniversity of OsloOsloNorway
| | - Dag Alnæs
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Bjørknes collegeOsloNorway
| | - Erlend S. Dørum
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Sunnaas Rehabilitation Hospital HTNesoddenNorway
- Department of PsychologyUniversity of OsloOsloNorway
| | - Anne‐Marthe Sanders
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Sunnaas Rehabilitation Hospital HTNesoddenNorway
- Department of PsychologyUniversity of OsloOsloNorway
| | - Kristine M. Ulrichsen
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Sunnaas Rehabilitation Hospital HTNesoddenNorway
- Department of PsychologyUniversity of OsloOsloNorway
| | - Jennifer Monereo Sánchez
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
| | - Hege Ihle‐Hansen
- Department of Geriatric MedicineOslo University HospitalOsloNorway
| | | | - Lars T. Westlye
- NORMENT, Division of Mental Health and AddictionOslo University Hospital & Institute of Clinical Medicine, University of OsloOsloNorway
- Department of PsychologyUniversity of OsloOsloNorway
- KG Jebsen Centre for Neurodevelopmental Disorders, University of OsloOsloNorway
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