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Kim Y, Lee JH, Park JC, Kwon J, Kim H, Seo J, Min BK. Neuromodulation of inhibitory control using phase-lagged transcranial alternating current stimulation. J Neuroeng Rehabil 2024; 21:93. [PMID: 38816860 PMCID: PMC11138099 DOI: 10.1186/s12984-024-01385-y] [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: 01/04/2024] [Accepted: 05/15/2024] [Indexed: 06/01/2024] Open
Abstract
BACKGROUND Transcranial alternating current stimulation (tACS) is a prominent non-invasive brain stimulation method for modulating neural oscillations and enhancing human cognitive function. This study aimed to investigate the effects of individualized theta tACS delivered in-phase and out-of-phase between the dorsal anterior cingulate cortex (dACC) and left dorsolateral prefrontal cortex (lDLPFC) during inhibitory control performance. METHODS The participants engaged in a Stroop task with phase-lagged theta tACS over individually optimized high-density electrode montages targeting the dACC and lDLPFC. We analyzed task performance, event-related potentials, and prestimulus electroencephalographic theta and alpha power. RESULTS We observed significantly reduced reaction times following out-of-phase tACS, accompanied by reduced frontocentral N1 and N2 amplitudes, enhanced parieto-occipital P1 amplitudes, and pronounced frontocentral late sustained potentials. Out-of-phase stimulation also resulted in significantly higher prestimulus frontocentral theta and alpha activity. CONCLUSIONS These findings suggest that out-of-phase theta tACS potently modulates top-down inhibitory control, supporting the feasibility of phase-lagged tACS to enhance inhibitory control performance.
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Affiliation(s)
- Yukyung Kim
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
| | - Je-Hyeop Lee
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
- BK21 Four Institute of Precision Public Health, Korea University, Seoul, 02841, Korea
| | - Je-Choon Park
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
| | - Jeongwook Kwon
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
| | - Hyoungkyu Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science, Sungkyunkwan University, Suwon, 16419, Korea
- Institute of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
| | - Jeehye Seo
- BK21 Four Institute of Precision Public Health, Korea University, Seoul, 02841, Korea
- Institute of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea
| | - Byoung-Kyong Min
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea.
- BK21 Four Institute of Precision Public Health, Korea University, Seoul, 02841, Korea.
- Institute of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea.
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2
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Seo J, Lee J, Min BK. Out-of-phase transcranial alternating current stimulation modulates the neurodynamics of inhibitory control. Neuroimage 2024; 292:120612. [PMID: 38648868 DOI: 10.1016/j.neuroimage.2024.120612] [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: 01/19/2024] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Transcranial alternating current stimulation (tACS) is an efficient neuromodulation technique that enhances cognitive function in a non-invasive manner. Using functional magnetic resonance imaging, we investigated whether tACS with different phase lags (0° and 180°) between the dorsal anterior cingulate and left dorsolateral prefrontal cortices modulated inhibitory control performance during the Stroop task. We found out-of-phase tACS mediated improvements in task performance, which was neurodynamically reflected as putamen, dorsolateral prefrontal, and primary motor cortical activation as well as prefrontal-based top-down functional connectivity. Our observations uncover the neurophysiological bases of tACS-phase-dependent neuromodulation and provide a feasible non-invasive approach to effectively modulate inhibitory control.
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Affiliation(s)
- Jeehye Seo
- Institute of Brain and Cognitive Engineering, Korea University, Seoul 02841, Korea; BK21 Four Institute of Precision Public Health, Korea University, Seoul 02841, Korea
| | - Jehyeop Lee
- BK21 Four Institute of Precision Public Health, Korea University, Seoul 02841, Korea; Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Korea
| | - Byoung-Kyong Min
- Institute of Brain and Cognitive Engineering, Korea University, Seoul 02841, Korea; BK21 Four Institute of Precision Public Health, Korea University, Seoul 02841, Korea; Department of Brain and Cognitive Engineering, Korea University, Seoul 02841, Korea.
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3
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Fujiyama H, Williams A, Tan J, Levin O, Hinder MR. Comparison of online and offline applications of dual-site transcranial alternating current stimulation (tACS) over the pre-supplementary motor area (preSMA) and right inferior frontal gyrus (rIFG) for improving response inhibition. Neuropsychologia 2023; 191:108737. [PMID: 37995902 DOI: 10.1016/j.neuropsychologia.2023.108737] [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: 07/17/2023] [Revised: 09/25/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023]
Abstract
The efficacy of transcranial alternating current stimulation (tACS) is thought to be brain state-dependent, such that tACS during task performance would be hypothesised to offer greater potential for improving performance compared to tACS at rest. However, to date, no empirical study has tested this postulation. The current study compared the effects of dual-site beta tACS applied during a stop signal task (online) to the effects of the same tACS protocol applied prior to the task (offline) and a sham control stimulation in 53 young, healthy adults (32 female; 18-35 yrs). The right inferior frontal gyrus (rIFG) and centre (midline) of the pre-supplementary motor area (preSMA), which are thought to play critical roles in action cancellation, were simultaneously stimulated, sending phase-synchronised stimulation for 15 min with the aim of increasing functional connectivity. The offline group showed significant within-group improvement in response inhibition without showing overt task-related changes in functional connectivity measured with EEG connectivity analysis, suggesting offline tACS is efficacious in inducing behavioural changes potentially via a post-stimulation early plasticity mechanism. In contrast, neither the online nor sham group showed significant improvements in response inhibition. However, EEG connectivity analysis revealed significantly increased task-related functional connectivity following online stimulation and a medium effect size observed in correlation analyses suggested that an increase in functional connectivity in the beta band at rest was potentially associated with an improvement in response inhibition. Overall, the results indicate that both online and offline dual-site beta tACS can be beneficial in improving inhibitory control via distinct underlying mechanisms.
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Affiliation(s)
- Hakuei Fujiyama
- School of Psychology, Murdoch University, Western Australia, Australia; Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Western Australia, Australia; Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Western Australia, Australia.
| | | | - Jane Tan
- School of Psychology, Murdoch University, Western Australia, Australia; Centre for Healthy Ageing, Health Futures Institute, Murdoch University, Western Australia, Australia
| | - Oron Levin
- Department of Health Promotion and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania; Movement Control & Neuroplasticity Research Group, Group Biomedical Sciences, Catholic University Leuven, Leuven, Belgium
| | - Mark R Hinder
- Sensorimotor Neuroscience and Ageing Research Group, School of Psychological Sciences, College of Health and Medicine, University of Tasmania, Tasmania, Australia
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4
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Boetzel C, Stecher HI, Herrmann CS. ERP-aligned delta transcranial alternating current stimulation modulates the P3 amplitude. Int J Psychophysiol 2023; 193:112247. [PMID: 37769997 DOI: 10.1016/j.ijpsycho.2023.112247] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 08/31/2023] [Accepted: 09/23/2023] [Indexed: 10/02/2023]
Abstract
The underlying mechanisms of the event-related potential (ERP) generation are still under debate. One popular model considers the ERP as a superposition of phase-resets of ongoing endogenous oscillations of different frequencies. Brain oscillations have been shown to be modulated by transcranial alternating current stimulation (tACS). Thus, it seems feasible, that an ERP could be altered by modulating the contributing oscillations using tACS. One possible approach would be to target a frequency-matched stimulation signal to a specific ERP-component. One possible target for such an approach is the P3, which appears as delta/theta oscillations in the frequency-domain. Thus, an ERP-aligned stimulation in the delta/theta-range might be suitable to force synchronization in the stimulated frequency band and thus increase the amplitude of the P3 component. Building on an existing paradigm, in the present study 21 healthy participants received individualized ERP-aligned delta tACS and control stimulation while performing a visual task. The visual stimulation was matched to the continuous tACS in order to align the tACS peak with the P3 peak. Both the P3 amplitude and the evoked delta power were significantly increased after ERP-aligned tACS but not after control stimulation. The investigated behavioral parameter showed no stimulation dependent effect. Our results may provide new insights into the debate on the contribution of phase-reset mechanisms to the generation of ERPs and offer new opportunities for clinical trials.
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Affiliation(s)
- Cindy Boetzel
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence "Hearing for All", Carl von Ossietzky University, Oldenburg, Germany
| | - Heiko I Stecher
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence "Hearing for All", Carl von Ossietzky University, Oldenburg, Germany
| | - Christoph S Herrmann
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence "Hearing for All", Carl von Ossietzky University, Oldenburg, Germany; Neuroimaging Unit, European Medical School, Carl von Ossietzky University, Oldenburg, Germany; Research Center Neurosensory Science, Carl von Ossietzky University, Oldenburg, Germany.
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5
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Wang T, de Graaf T, Tanner L, Schuhmann T, Duecker F, Sack AT. Hemispheric Asymmetry in TMS-Induced Effects on Spatial Attention: A Meta-Analysis. Neuropsychol Rev 2023:10.1007/s11065-023-09614-2. [PMID: 37736863 DOI: 10.1007/s11065-023-09614-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 08/14/2023] [Indexed: 09/23/2023]
Abstract
Hemispheric asymmetry is a fundamental principle in the functional architecture of the brain. It plays an important role in attention research where right hemisphere dominance is core to many attention theories. Lesion studies seem to confirm such hemispheric dominance with patients being more likely to develop left hemineglect after right hemispheric stroke than vice versa. However, the underlying concept of hemispheric dominance is still not entirely clear. Brain stimulation studies using transcranial magnetic stimulation (TMS) might be able to illuminate this concept. To examine the putative hemispheric asymmetry in spatial attention, we conducted a meta-analysis of studies applying inhibitory TMS protocols to the left or right posterior parietal cortices (PPC), assessing effects on attention biases with the landmark and line bisection task. A total of 18 studies including 222 participants from 1994 to February 2022 were identified. The analysis revealed a significant shift of the perceived midpoint towards the ipsilateral hemifield after right PPC suppression (Cohen's d = 0.52), but no significant effect after left PPC suppression (Cohen's d = 0.26), suggesting a hemispheric asymmetry even though the subgroup difference does not reach significance (p = .06). A complementary Bayesian meta-analysis revealed a high probability of at least a medium effect size after right PPC disruption versus a low probability after left PPC disruption. This is the first quantitative meta-analysis supporting right hemisphere-specific TMS-induced spatial attention deficits, mimicking hemineglect in healthy participants. We discuss the result in the light of prominent attention theories, ultimately concluding how difficult it remains to differentiate between these theories based on attentional bias scores alone.
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Affiliation(s)
- Ting Wang
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands.
- Maastricht Brain Imaging Centre, Maastricht, the Netherlands.
| | - Tom de Graaf
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands
- Maastricht Brain Imaging Centre, Maastricht, the Netherlands
| | - Lisabel Tanner
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands
| | - Teresa Schuhmann
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands
- Maastricht Brain Imaging Centre, Maastricht, the Netherlands
| | - Felix Duecker
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands
- Maastricht Brain Imaging Centre, Maastricht, the Netherlands
| | - Alexander T Sack
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD, Maastricht, the Netherlands
- Maastricht Brain Imaging Centre, Maastricht, the Netherlands
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University Medical Centre+, Brain+Nerve Centre, Maastricht, the Netherlands
- Centre for Integrative Neuroscience, Faculty of Psychology and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, the Netherlands
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6
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Arrington CN, Ossowski AE, Baig H, Persichetti E, Morris R. The Impact of Transcranial Magnetic Stimulation on Reading Processes: A Systematic Review. Neuropsychol Rev 2023; 33:255-277. [PMID: 35119625 PMCID: PMC9349478 DOI: 10.1007/s11065-022-09534-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/14/2021] [Indexed: 01/26/2023]
Abstract
The current systematic review examines the behavioral effects of TMS on reading. Transcranial magnetic stimulation (TMS) to targeted nodes of the brain's reading network has been shown to impact reading. Extracted data included (a) study characteristics, (b) methodology, (c) targeted nodes, (d) control paradigm, (e) type of reading task, (f) adverse effects, and (g) main findings. Data was classified by type of reading task: 1) phonological processing, 2) semantic judgment, 3) lexical decision, 4) whole word reading, and 5) visual or text characteristics. Seventy records from 46 studies (n = 844) were identified. Results indicate that TMS modulates semantic judgments when focused in the anterior aspects of the reading circuit, phonological processes after stimulation within the dorsal circuit, and impacts single word recognition and contextual reading when administered to the ventral circuit. Findings suggest that changes in specific behavioral aspects of reading following TMS may contribute to identification of foci for use as part of reading interventions.
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Affiliation(s)
- C Nikki Arrington
- Department of Psychology, Georgia State University, Atlanta, GA, 30303, USA. .,GSU/GT Center for Advanced Brain Imaging, Atlanta, GA, 30318, USA.
| | | | - Humza Baig
- Department of Psychology, Georgia State University, Atlanta, GA, 30303, USA.,GSU/GT Center for Advanced Brain Imaging, Atlanta, GA, 30318, USA
| | - Eileen Persichetti
- GSU/GT Center for Advanced Brain Imaging, Atlanta, GA, 30318, USA.,School of Social Work, Boston University, Boston, MA, 02215, USA
| | - Robin Morris
- Department of Psychology, Georgia State University, Atlanta, GA, 30303, USA.,GSU/GT Center for Advanced Brain Imaging, Atlanta, GA, 30318, USA
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7
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Cheng Y, Chen Y, Fan Y, Chen C. Neuromodulation of the right temporoparietal junction alters amygdala functional connectivity to authority pressure. Hum Brain Mapp 2022; 43:5605-5615. [PMID: 36441845 PMCID: PMC9704788 DOI: 10.1002/hbm.26037] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 06/28/2022] [Accepted: 07/20/2022] [Indexed: 01/15/2023] Open
Abstract
Past historical events and experimental research have shown that complying with orders from an authority has a strong impact on harming/destructive behavior, but no one has ever looked into the potential intervention and its neural underpinning to reveal the toll of coercion. We used a paradigm of virtual obedience to authority, in which an experimenter ordered a volunteer to press a handheld button to initiate actions that carried different consequences, including harming or helping others. In this study, we scanned the brain with functional neuroimaging and applied transcranial direct current stimulation (tDCS) to modulate the activation of the right temporoparietal junction (rTPJ) in healthy volunteers in a single-blinded, sham-controlled, crossover trial with anodal, cathodal, and sham stimulation. We observed that cathodal stimulation, compared to anodal and sham stimulation, significantly reduced reaction times (RTs) to initiating harming actions. The effect of tDCS on the rTPJ, orbitofrontal cortex, and anterior cingulate cortex had opposite directions depending on coercive harming or helping actions. Cathodal tDCS-induced changes in the strength of the functional connectivity between the rTPJ and amygdala predicted the effect of cathodal tDCS on harming RTs. The findings provide evidence supporting the rTPJ having a role in coercion-induced changes in the sense of agency. Neuromodulation with tDCS might help in unveiling the power of authority and assisting in the emergence of prosocial behavior, thus shedding light on coping strategies against coercion beyond merely examining its effects.
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Affiliation(s)
- Yawei Cheng
- Department of Physical Medicine and RehabilitationNational Yang Ming Chiao Tung University HospitalYilanTaiwan
- Institute of Neuroscience and Brain Research CenterNational Yang Ming Chiao Tung UniversityTaipeiTaiwan
- Department of Education and ResearchTaipei City HospitalTaipeiTaiwan
| | - Yu‐Chun Chen
- Department of Physical EducationNational Taiwan University of SportTaichungTaiwan
| | - Yang‐Teng Fan
- Graduate Institute of MedicineYuan Ze UniversityTaoyuanTaiwan
| | - Chenyi Chen
- Graduate Institute of Injury Prevention and Control, College of Public HealthTaipei Medical UniversityTaipeiTaiwan
- Brain and Consciousness Research Center, Shuang‐Ho HospitalTaipei Medical UniversityNew Taipei CityTaiwan
- Graduate Institute of Mind, Brain and Consciousness, College of Humanities and Social SciencesTaipei Medical UniversityTaipeiTaiwan
- Psychiatric Research Center, Wan Fang HospitalTaipei Medical UniversityTaipeiTaiwan
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8
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Using noise for the better: The effects of transcranial random noise stimulation on the brain and behavior. Neurosci Biobehav Rev 2022; 138:104702. [PMID: 35595071 DOI: 10.1016/j.neubiorev.2022.104702] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 01/12/2022] [Accepted: 05/13/2022] [Indexed: 12/22/2022]
Abstract
Van der Groen, O., Potok, W., Wenderoth, N., Edwards, G., Mattingley, J.B. and Edwards, D. Using noise for the better: The effects of transcranial random noise stimulation on the brain and behavior. NEUROSCI BIOBEHAV REV X (X) XXX-XXX 2021.- Transcranial random noise stimulation (tRNS) is a non-invasive electrical brain stimulation method that is increasingly employed in studies of human brain function and behavior, in health and disease. tRNS is effective in modulating perception acutely and can improve learning. By contrast, its effectiveness for modulating higher cognitive processes is variable. Prolonged stimulation with tRNS, either as one longer application, or multiple shorter applications, may engage plasticity mechanisms that can result in long-term benefits. Here we provide an overview of the current understanding of the effects of tRNS on the brain and behavior and provide some specific recommendations for future research.
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Lehmann SJ, Corneil BD. Completing the puzzle: Why studies in non-human primates are needed to better understand the effects of non-invasive brain stimulation. Neurosci Biobehav Rev 2021; 132:1074-1085. [PMID: 34742722 DOI: 10.1016/j.neubiorev.2021.10.040] [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: 06/11/2021] [Revised: 09/29/2021] [Accepted: 10/31/2021] [Indexed: 11/27/2022]
Abstract
Brain stimulation is a core method in neuroscience. Numerous non-invasive brain stimulation (NIBS) techniques are currently in use in basic and clinical research, and recent advances promise the ability to non-invasively access deep brain structures. While encouraging, there is a surprising gap in our understanding of precisely how NIBS perturbs neural activity throughout an interconnected network, and how such perturbed neural activity ultimately links to behaviour. In this review, we will consider why non-human primate (NHP) models of NIBS are ideally situated to address this gap in knowledge, and why the oculomotor network that moves our line of sight offers a particularly valuable platform in which to empirically test hypothesis regarding NIBS-induced changes in brain and behaviour. NHP models of NIBS will enable investigation of the complex, dynamic effects of brain stimulation across multiple hierarchically interconnected brain areas, networks, and effectors. By establishing such links between brain and behavioural output, work in NHPs can help optimize experimental and therapeutic approaches, improve NIBS efficacy, and reduce side-effects of NIBS.
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Affiliation(s)
- Sebastian J Lehmann
- Department of Physiology and Pharmacology, Western University, London, Ontario, N6A 5B7, Canada.
| | - Brian D Corneil
- Department of Physiology and Pharmacology, Western University, London, Ontario, N6A 5B7, Canada; Department of Psychology, Western University, London, Ontario, N6A 5B7, Canada; Robarts Research Institute, London, Ontario, N6A 5B7, Canada.
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10
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Stecher HI, Notbohm A, Kasten FH, Herrmann CS. A Comparison of Closed Loop vs. Fixed Frequency tACS on Modulating Brain Oscillations and Visual Detection. Front Hum Neurosci 2021; 15:661432. [PMID: 34248524 PMCID: PMC8261289 DOI: 10.3389/fnhum.2021.661432] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/03/2021] [Indexed: 12/28/2022] Open
Abstract
Transcranial alternating current stimulation has emerged as an effective tool for the exploration of brain oscillations. By applying a weak alternating current between electrodes placed on the scalp matched to the endogenous frequency, tACS enables the specific modulation of targeted brain oscillations This results in alterations in cognitive functions or persistent physiological changes. Most studies that utilize tACS determine a fixed stimulation frequency prior to the stimulation that is kept constant throughout the experiment. Yet it is known that brain rhythms can encounter shifts in their endogenous frequency. This could potentially move the ongoing brain oscillations into a frequency region where it is no longer affected by the stimulation, thereby decreasing or negating the effect of tACS. Such an effect of a mismatch between stimulation frequency and endogenous frequency on the outcome of stimulation has been shown before for the parietal alpha-activity. In this study, we employed an intermittent closed loop stimulation protocol, where the stimulation is divided into short epochs, between which an EEG is recorded and rapidly analyzed to determine a new stimulation frequency for the next stimulation epoch. This stimulation protocol was tested in a three-group study against a classical fixed stimulation protocol and a sham-treatment. We targeted the parietal alpha rhythm and hypothesized that this setup will ensure a constant close match between the frequencies of tACS and alpha activity. This closer match should lead to an increased modulation of detection of visual luminance changes depending on the phase of the tACS and an increased rise in alpha peak power post stimulation when compared to a protocol with fixed pre-determined stimulation frequency. Contrary to our hypothesis, our results show that only a fixed stimulation protocol leads to a persistent increase in post-stimulation alpha power as compared to sham. Furthermore, in none of the stimulated groups significant modulation of detection performance occurred. While the lack of behavioral effects is inconclusive due to the short selection of different phase bins and trials, the physiological results suggest that a constant stimulation with a fixed frequency is actually beneficial, when the goal is to produce persistent synaptic changes.
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Affiliation(s)
- Heiko I Stecher
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster of Excellence "Hearing4all", Carl von Ossietzky University, Oldenburg, Germany
| | - Annika Notbohm
- Department of Neurological Rehabilitation, Municipal Hospital of Bremen, Bremen, Germany
| | - Florian H Kasten
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster of Excellence "Hearing4all", Carl von Ossietzky University, Oldenburg, Germany
| | - Christoph S Herrmann
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster of Excellence "Hearing4all", Carl von Ossietzky University, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University, Oldenburg, Germany
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11
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Hobot J, Klincewicz M, Sandberg K, Wierzchoń M. Causal Inferences in Repetitive Transcranial Magnetic Stimulation Research: Challenges and Perspectives. Front Hum Neurosci 2021; 14:586448. [PMID: 33584220 PMCID: PMC7873895 DOI: 10.3389/fnhum.2020.586448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/30/2020] [Indexed: 11/29/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is used to make inferences about relationships between brain areas and their functions because, in contrast to neuroimaging tools, it modulates neuronal activity. The central aim of this article is to critically evaluate to what extent it is possible to draw causal inferences from repetitive TMS (rTMS) data. To that end, we describe the logical limitations of inferences based on rTMS experiments. The presented analysis suggests that rTMS alone does not provide the sort of premises that are sufficient to warrant strong inferences about the direct causal properties of targeted brain structures. Overcoming these limitations demands a close look at the designs of rTMS studies, especially the methodological and theoretical conditions which are necessary for the functional decomposition of the relations between brain areas and cognitive functions. The main points of this article are that TMS-based inferences are limited in that stimulation-related causal effects are not equivalent to structure-related causal effects due to TMS side effects, the electric field distribution, and the sensitivity of neuroimaging and behavioral methods in detecting structure-related effects and disentangling them from confounds. Moreover, the postulated causal effects can be based on indirect (network) effects. A few suggestions on how to manage some of these limitations are presented. We discuss the benefits of combining rTMS with neuroimaging in experimental reasoning and we address the restrictions and requirements of rTMS control conditions. The use of neuroimaging and control conditions allows stronger inferences to be gained, but the strength of the inferences that can be drawn depends on the individual experiment's designs. Moreover, in some cases, TMS might not be an appropriate method of answering causality-related questions or the hypotheses have to account for the limitations of this technique. We hope this summary and formalization of the reasoning behind rTMS research can be of use not only for scientists and clinicians who intend to interpret rTMS results causally but also for philosophers interested in causal inferences based on brain stimulation research.
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Affiliation(s)
- Justyna Hobot
- Consciousness Lab, Psychology Institute, Jagiellonian University, Krakow, Poland
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Michał Klincewicz
- Cognitive Science, Institute of Philosophy, Jagiellonian University, Krakow, Poland
- Department of Cognitive Science and Artificial Intelligence, Tilburg University, Tilburg, Netherlands
| | - Kristian Sandberg
- Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
- Center of Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark
| | - Michał Wierzchoń
- Consciousness Lab, Psychology Institute, Jagiellonian University, Krakow, Poland
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12
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Min BK, Hämäläinen MS, Pantazis D. New Cognitive Neurotechnology Facilitates Studies of Cortical-Subcortical Interactions. Trends Biotechnol 2020; 38:952-962. [PMID: 32278504 PMCID: PMC7442676 DOI: 10.1016/j.tibtech.2020.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 03/06/2020] [Accepted: 03/06/2020] [Indexed: 11/26/2022]
Abstract
Most of the studies employing neuroimaging have focused on cortical and subcortical signals individually to obtain neurophysiological signatures of cognitive functions. However, understanding the dynamic communication between the cortex and subcortical structures is essential for unraveling the neural correlates of cognition. In this quest, magnetoencephalography (MEG) and electroencephalography (EEG) are the methods of choice because they are noninvasive electrophysiological recording techniques with high temporal resolution. Sophisticated MEG/EEG source estimation techniques and network analysis methods, developed recently, can provide a more comprehensive understanding of the neurophysiological mechanisms of fundamental cognitive processes. Used together with noninvasive modulation of cortical-subcortical communication, these approaches may open up new possibilities for expanding the repertoire of noninvasive cognitive neurotechnology.
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Affiliation(s)
- Byoung-Kyong Min
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea; McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Matti S Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Dimitrios Pantazis
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Bland NS, Sale MV. Current challenges: the ups and downs of tACS. Exp Brain Res 2019; 237:3071-3088. [DOI: 10.1007/s00221-019-05666-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/09/2019] [Indexed: 02/08/2023]
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Vosskuhl J, Strüber D, Herrmann CS. Non-invasive Brain Stimulation: A Paradigm Shift in Understanding Brain Oscillations. Front Hum Neurosci 2018; 12:211. [PMID: 29887799 PMCID: PMC5980979 DOI: 10.3389/fnhum.2018.00211] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/07/2018] [Indexed: 11/13/2022] Open
Abstract
Cognitive neuroscience set out to understand the neural mechanisms underlying cognition. One central question is how oscillatory brain activity relates to cognitive processes. Up to now, most of the evidence supporting this relationship was correlative in nature. This situation changed dramatically with the recent development of non-invasive brain stimulation (NIBS) techniques, which open up new vistas for neuroscience by allowing researchers for the first time to validate their correlational theories by manipulating brain functioning directly. In this review, we focus on transcranial alternating current stimulation (tACS), an electrical brain stimulation method that applies sinusoidal currents to the intact scalp of human individuals to directly interfere with ongoing brain oscillations. We outline how tACS can impact human brain oscillations by employing different levels of observation from non-invasive tACS application in healthy volunteers and intracranial recordings in patients to animal studies demonstrating the effectiveness of alternating electric fields on neurons in vitro and in vivo. These findings likely translate to humans as comparable effects can be observed in human and animal studies. Neural entrainment and plasticity are suggested to mediate the behavioral effects of tACS. Furthermore, we focus on mechanistic theories about the relationship between certain cognitive functions and specific parameters of brain oscillaitons such as its amplitude, frequency, phase and phase coherence. For each of these parameters we present the current state of testing its functional relevance by means of tACS. Recent developments in the field of tACS are outlined which include the stimulation with physiologically inspired non-sinusoidal waveforms, stimulation protocols which allow for the observation of online-effects, and closed loop applications of tACS.
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Affiliation(s)
- Johannes Vosskuhl
- Experimental Psychology Lab, Center for Excellence “Hearing4all,” European Medical School, University of Oldenburg, Oldenburg, Germany
| | - Daniel Strüber
- Experimental Psychology Lab, Center for Excellence “Hearing4all,” European Medical School, University of Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Christoph S. Herrmann
- Experimental Psychology Lab, Center for Excellence “Hearing4all,” European Medical School, University of Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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Hsu TY, Juan CH, Tseng P. Individual Differences and State-Dependent Responses in Transcranial Direct Current Stimulation. Front Hum Neurosci 2016; 10:643. [PMID: 28066214 PMCID: PMC5174116 DOI: 10.3389/fnhum.2016.00643] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/05/2016] [Indexed: 12/25/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been extensively used to examine whether neural activities can be selectively increased or decreased with manipulations of current polarity. Recently, the field has reevaluated the traditional anodal-increase and cathodal-decrease assumption due to the growing number of mixed findings that report the effects of the opposite directions. Therefore, the directionality of tDCS polarities and how it affects each individual still remain unclear. In this study, we used a visual working memory (VWM) paradigm and systematically manipulated tDCS polarities, types of different independent baseline measures, and task difficulty to investigate how these factors interact to determine the outcome effect of tDCS. We observed that only low-performers, as defined by their no-tDCS corsi block tapping (CBT) performance, persistently showed a decrement in VWM performance after anodal stimulation, whereas no tDCS effect was found when participants were divided by their performance in digit span. In addition, only the optimal level of task difficulty revealed any significant tDCS effect. All these findings were consistent across different blocks, suggesting that the tDCS effect was stable across a short period of time. Lastly, there was a high degree of intra-individual consistency in one’s responsiveness to tDCS, namely that participants who showed positive or negative effect to anodal stimulation are also more likely to show the same direction of effects for cathodal stimulation. Together, these findings imply that tDCS effect is interactive and state dependent: task difficulty and consistent individual differences modulate one’s responsiveness to tDCS, while researchers’ choices of independent behavioral baseline measures can also critically affect how the effect of tDCS is evaluated. These factors together are likely the key contributors to the wide range of “noises” in tDCS effects between individuals, between stimulation protocols, and between different studies in the literature. Future studies using tDCS, and possibly tACS, should take such state-dependent condition in tDCS responsiveness into account.
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Affiliation(s)
- Tzu-Yu Hsu
- Research Center of Brain and Consciousness, College of Humanities and Social Sciences, Taipei Medical UniversityTaipei, Taiwan; Shuang-Ho Hospital, Taipei Medical UniversityNew Taipei City, Taiwan; Graduate Institute of Health and Biotechnology Law, Taipei Medical UniversityTaipei, Taiwan
| | - Chi-Hung Juan
- Institute of Cognitive Neuroscience, National Central University Taoyuan, Taiwan
| | - Philip Tseng
- Research Center of Brain and Consciousness, College of Humanities and Social Sciences, Taipei Medical UniversityTaipei, Taiwan; Shuang-Ho Hospital, Taipei Medical UniversityNew Taipei City, Taiwan; Graduate Institute of Humanities in Medicine, Taipei Medical UniversityTaipei, Taiwan
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