201
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Wischnewski M, Schutter DJ, Nitsche MA. Effects of beta-tACS on corticospinal excitability: A meta-analysis. Brain Stimul 2019; 12:1381-1389. [DOI: 10.1016/j.brs.2019.07.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/05/2019] [Accepted: 07/25/2019] [Indexed: 01/08/2023] Open
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202
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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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203
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Recovering Brain Dynamics During Concurrent tACS-M/EEG: An Overview of Analysis Approaches and Their Methodological and Interpretational Pitfalls. Brain Topogr 2019; 32:1013-1019. [DOI: 10.1007/s10548-019-00727-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/20/2019] [Indexed: 12/27/2022]
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204
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State-Dependent Effects of Transcranial Oscillatory Currents on the Motor System during Action Observation. Sci Rep 2019; 9:12858. [PMID: 31492895 PMCID: PMC6731229 DOI: 10.1038/s41598-019-49166-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 08/16/2019] [Indexed: 12/24/2022] Open
Abstract
We applied transcranial alternating current stimulation (tACS) to the primary motor cortex (M1) at different frequencies during an index–thumb pinch-grip observation task. To estimate changes in the corticospinal output, we used the size of motor evoked potentials (MEPs) obtained by transcranial magnetic stimulation (TMS) of M1 using an online MRI-guided simultaneous TMS-tACS approach. The results of the beta-tACS confirm a non-selective increase in corticospinal excitability in subjects at rest; an increase was observed for both of the tested hand muscles, the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM). However, during action observation of the pinch-grip movement, the increase of corticospinal excitability was only observed for the prime mover FDI muscle and took place during alpha-tACS, while gamma-tACS affected both the FDI and control muscle (ADM) responses. These phenomena likely reflect the hypothesis that the mu and gamma rhythms specifically index the downstream modulation of primary sensorimotor areas by engaging mirror neuron activity. The current neuromodulation approach confirms that tACS can be used to induce neurophysiologically detectable state-dependent enhancement effects, even in complex motor-cognitive tasks.
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205
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Schwab BC, Misselhorn J, Engel AK. Modulation of large-scale cortical coupling by transcranial alternating current stimulation. Brain Stimul 2019; 12:1187-1196. [DOI: 10.1016/j.brs.2019.04.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 01/03/2023] Open
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206
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From correlation towards causality: modulating brain rhythms of pain using transcranial alternating current stimulation. Pain Rep 2019; 4:e723. [PMID: 31579843 PMCID: PMC6727992 DOI: 10.1097/pr9.0000000000000723] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/18/2019] [Accepted: 01/30/2019] [Indexed: 12/15/2022] Open
Abstract
Introduction Accumulating evidence suggests that neural oscillations at different frequencies and their synchrony between brain regions play a crucial role in the processing of nociceptive input and the emergence of pain. Most findings are limited by their correlative nature, however, which impedes causal inferences. Objective To move from correlative towards causal evidence, methods that allow to experimentally manipulate oscillatory brain activity are needed. Results Transcranial alternating current stimulation (tACS) is a noninvasive brain stimulation technique designed to modulate neural oscillations in a frequency specific manner and as such a suitable method to investigate the contribution of oscillatory brain activity to pain. Despite its appeal, tACS has been barely applied in the field of pain research. In the present review, we address this issue and discuss how tACS can be used to gather mechanistic evidence for the relationship between pain and neural oscillations in humans. Conclusions Transcranial alternating current stimulation holds great potential for the investigation of the neural mechanisms underlying pain and the development of new treatment approaches for chronic pain if necessary methodological precautions are taken.
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207
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Haberbosch L, Datta A, Thomas C, Jooß A, Köhn A, Rönnefarth M, Scholz M, Brandt SA, Schmidt S. Safety Aspects, Tolerability and Modeling of Retinofugal Alternating Current Stimulation. Front Neurosci 2019; 13:783. [PMID: 31440126 PMCID: PMC6692662 DOI: 10.3389/fnins.2019.00783] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 07/12/2019] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND While alternating current stimulation (ACS) is gaining relevance as a tool in research and approaching clinical applications, its mechanisms of action remain unclear. A review by Schutter and colleagues argues for a retinal origin of transcranial ACS' neuromodulatory effects. Interestingly, there is an alternative application form of ACS specifically targeting α-oscillations in the visual cortex via periorbital electrodes (retinofugal alternating current stimulation, rACS). To further compare these two methods and investigate retinal effects of ACS, we first aim to establish the safety and tolerability of rACS. OBJECTIVE The goal of our research was to evaluate the safety of rACS via finite-element modeling, theoretical safety limits and subjective report. METHODS 20 healthy subjects were stimulated with rACS as well as photic stimulation and reported adverse events following stimulation. We analyzed stimulation parameters at electrode level as well as distributed metric estimates from an ultra-high spatial resolution magnetic resonance imaging (MRI)-derived finite element human head model and compared them to existing safety limits. RESULTS Topographical modeling revealed the highest current densities in the anterior visual pathway, particularly retina and optic nerve. Stimulation parameters and finite element modeling estimates of rACS were found to be well below existing safety limits. No serious adverse events occurred. CONCLUSION Our findings are in line with existing safety guidelines for retinal and neural damage and establish the tolerability and feasibility of rACS. In comparison to tACS, retinofugal stimulation of the visual cortex provides an anatomically circumscribed model to systematically study the mechanisms of action of ACS.
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Affiliation(s)
- Linus Haberbosch
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Department of Endocrinology, Diabetes and Metabolism, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Abhishek Datta
- Research and Development, Soterix Medical, New York, NY, United States
| | - Chris Thomas
- Research and Development, Soterix Medical, New York, NY, United States
| | - Andreas Jooß
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Arvid Köhn
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Maria Rönnefarth
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Michael Scholz
- Neural Information Processing Group, Technical University of Berlin, Berlin, Germany
| | - Stephan A. Brandt
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Sein Schmidt
- Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
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208
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Posttraining Alpha Transcranial Alternating Current Stimulation Impairs Motor Consolidation in Elderly People. Neural Plast 2019; 2019:2689790. [PMID: 31428143 PMCID: PMC6681583 DOI: 10.1155/2019/2689790] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/27/2019] [Accepted: 06/13/2019] [Indexed: 11/23/2022] Open
Abstract
The retention of a new sequential motor skill relies on repeated practice and subsequent consolidation in the absence of active skill practice. While the early phase of skill acquisition remains relatively unaffected in older adults, posttraining consolidation appears to be selectively impaired by advancing age. Motor learning is associated with posttraining changes of oscillatory alpha and beta neuronal activities in the motor cortex. However, whether or not these oscillatory dynamics relate to posttraining consolidation and how they relate to the age-specific impairment of motor consolidation in older adults remains elusive. Transcranial alternating current stimulation (tACS) is a noninvasive brain stimulation technique capable of modulating such neuronal oscillations. Here, we examined whether tACS targeting M1 immediately following explicit motor sequence training is capable of modulating motor skill consolidation in older adults. In two sets of double-blind, sham-controlled experiments, tACS targeting left M1 was applied at either 10 Hz (alpha-tACS) or 20 Hz (beta-tACS) immediately after termination of a motor sequence training with the right (dominant) hand. Task performance was retested after an interval of 6 hours to assess consolidation of the training-acquired skill. EEG was recorded over left M1 to be able to detect local after-effects on oscillatory activity induced by tACS. Relative to the sham intervention, consolidation was selectively disrupted by posttraining alpha-tACS of M1, while posttraining beta-tACS of M1 had no effect on delayed retest performance compared to the sham intervention. No significant postinterventional changes of oscillatory activity in M1 were detected following alpha-tACS or beta-tACS. Our findings point to a frequency-specific interaction of tACS with posttraining motor memory processing and may suggest an inhibitory role of immediate posttraining alpha oscillations in M1 with respect to motor consolidation in healthy older adults.
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209
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Halje P, Brys I, Mariman JJ, da Cunha C, Fuentes R, Petersson P. Oscillations in cortico-basal ganglia circuits: implications for Parkinson’s disease and other neurologic and psychiatric conditions. J Neurophysiol 2019; 122:203-231. [DOI: 10.1152/jn.00590.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cortico-basal ganglia circuits are thought to play a crucial role in the selection and control of motor behaviors and have also been implicated in the processing of motivational content and in higher cognitive functions. During the last two decades, electrophysiological recordings in basal ganglia circuits have shown that several disease conditions are associated with specific changes in the temporal patterns of neuronal activity. In particular, synchronized oscillations have been a frequent finding suggesting that excessive synchronization of neuronal activity may be a pathophysiological mechanism involved in a wide range of neurologic and psychiatric conditions. We here review the experimental support for this hypothesis primarily in relation to Parkinson’s disease but also in relation to dystonia, essential tremor, epilepsy, and psychosis/schizophrenia.
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Affiliation(s)
- Pär Halje
- Group for Integrative Neurophysiology and Neurotechnology, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Ivani Brys
- Federal University of Vale do São Francisco, Petrolina, Brazil
| | - Juan J. Mariman
- Research and Development Direction, Universidad Tecnológica de Chile, Inacap, Santiago, Chile
- Department of Physical Therapy, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Department of Physical Therapy, Faculty of Arts and Physical Education, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile
| | - Claudio da Cunha
- Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Programas de Pós-Graduação em Farmacologia e Bioquímica, Universidade Federal do Paraná, Curitiba, Brazil
| | - Romulo Fuentes
- Department of Neurocience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Per Petersson
- Group for Integrative Neurophysiology and Neurotechnology, Department of Experimental Medical Science, Lund University, Lund, Sweden
- Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
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210
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Clancy KJ, Baisley SK, Albizu A, Kartvelishvili N, Ding M, Li W. Lasting connectivity increase and anxiety reduction via transcranial alternating current stimulation. Soc Cogn Affect Neurosci 2019; 13:1305-1316. [PMID: 30380131 PMCID: PMC6277743 DOI: 10.1093/scan/nsy096] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 10/28/2018] [Indexed: 12/12/2022] Open
Abstract
Growing evidence of transcranial alternating current stimulation (tACS) modulating intrinsic neural oscillations has spawned interest in applying tACS to treat psychiatric disorders associated with aberrant neural oscillations. The alpha rhythmic activity is known to dominate neural oscillations at the awake, restful state, while attenuated resting-state alpha activity has been implicated in anxious mood. Administering repeated alpha-frequency tACS (α-tACS; at individual peak alpha frequency; 8–12 Hz) over four consecutive days (in the experiment group, sham stimulation in the control group), we demonstrated immediate and lasting (>24 h) increases in resting-state posterior ➔frontal connectivity in the alpha frequency, quantified by Granger causality. Critically, this connectivity enhancement was accompanied by sustained reductions in both anxious arousal and negative perception of sensory stimuli. Resting-state alpha power also increased, albeit only transiently, reversing to the baseline level within 24 h after tACS. Therefore, the lasting enhancement of long-range alpha connectivity due to α-tACS differs from local alpha activity that is nonetheless conserved, highlighting the adaptability of alpha oscillatory networks. In light of increasing recognition of large-scale network dysfunctions as a transdiagnostic pathophysiology of psychiatric disorders, this enduring connectivity plasticity, along with the behavioral improvements, paves the way for tACS applications in clinical interventions of psychiatric ‘oscillopathies’.
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Affiliation(s)
- Kevin J Clancy
- Department of Psychology, Florida State University, Tallahassee, FL, USA
| | - Sarah K Baisley
- Department of Psychology, Florida State University, Tallahassee, FL, USA
| | - Alejandro Albizu
- Department of Psychology, Florida State University, Tallahassee, FL, USA
| | | | - Mingzhou Ding
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Wen Li
- Department of Psychology, Florida State University, Tallahassee, FL, USA
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211
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Banerjee S, Grover S, Sridharan D. Unraveling Causal Mechanisms of Top-Down and Bottom-Up Visuospatial Attention with Non-invasive Brain Stimulation. J Indian Inst Sci 2019; 97:451-475. [PMID: 31231154 PMCID: PMC6588534 DOI: 10.1007/s41745-017-0046-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 09/29/2017] [Indexed: 12/22/2022]
Abstract
Attention is a process of selection that allows us to intelligently navigate the abundance of information in our world. Attention can be either directed voluntarily based on internal goals-"top-down" or goal-directed attention-or captured automatically, by salient stimuli-"bottom-up" or stimulus-driven attention. Do these two modes of attention control arise from same or different brain circuits? Do they share similar or distinct neural mechanisms? In this review, we explore this dichotomy between the neural bases of top-down and bottom-up attention control, with a special emphasis on insights gained from non-invasive neurostimulation techniques, specifically, transcranial magnetic stimulation (TMS). TMS enables spatially focal and temporally precise manipulation of brain activity. We explore a significant literature devoted to investigating the role of fronto-parietal brain regions in top-down and bottom-up attention with TMS, and highlight key areas of convergence and debate. We also discuss recent advances in combinatorial paradigms that combine TMS with other imaging modalities, such as functional magnetic resonance imaging or electroencephalography. These paradigms are beginning to bridge essential gaps in our understanding of the neural pathways by which TMS affects behavior, and will prove invaluable for unraveling mechanisms of attention control, both in health and in disease.
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Affiliation(s)
- Sanjna Banerjee
- Centre for Neuroscience, Indian Institute of Science, Bangalore, 560012 India
| | - Shrey Grover
- Centre for Neuroscience, Indian Institute of Science, Bangalore, 560012 India
| | - Devarajan Sridharan
- Centre for Neuroscience, Indian Institute of Science, Bangalore, 560012 India
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212
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Sreeraj VS, Shivakumar V, Sowmya S, Bose A, Nawani H, Narayanaswamy JC, Venkatasubramanian G. Online Theta Frequency Transcranial Alternating Current Stimulation for Cognitive Remediation in Schizophrenia: A Case Report and Review of Literature. J ECT 2019; 35:139-143. [PMID: 30024457 DOI: 10.1097/yct.0000000000000523] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Transcranial alternating current stimulation (tACS), a noninvasive brain stimulation technique that uses low-intensity alternating current, has been postulated to be a potential therapeutic option in treating the cognitive deficits in schizophrenia. Transcranial alternating current stimulation synchronizes the neural oscillations to the applied stimulation frequency in the stimulated cortical regions. In this report, we have reviewed the literature pertinent to the clinical application of tACS in psychiatric disorders; in addition, we have described the clinical use of online theta tACS in a schizophrenia patient with cognitive deficits. Online theta tACS led to improvement in working memory, attention, processing speed, and emotional processing. The beneficial effect of tACS persisted during reassessment of the patient after 50 days. Transcranial alternating current stimulation, given its noninvasiveness, safety, and ease of administration, has the potential to ameliorate cognitive deficits in neuropsychiatric disorders like schizophrenia.
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Affiliation(s)
- Vanteemar S Sreeraj
- From the WISER Program, Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru, India
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213
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Benwell CSY, London RE, Tagliabue CF, Veniero D, Gross J, Keitel C, Thut G. Frequency and power of human alpha oscillations drift systematically with time-on-task. Neuroimage 2019; 192:101-114. [PMID: 30844505 PMCID: PMC6503153 DOI: 10.1016/j.neuroimage.2019.02.067] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 01/12/2019] [Accepted: 02/27/2019] [Indexed: 11/11/2022] Open
Abstract
Oscillatory neural activity is a fundamental characteristic of the mammalian brain spanning multiple levels of spatial and temporal scale. Current theories of neural oscillations and analysis techniques employed to investigate their functional significance are based on an often implicit assumption: In the absence of experimental manipulation, the spectral content of any given EEG- or MEG-recorded neural oscillator remains approximately stationary over the course of a typical experimental session (∼1 h), spontaneously fluctuating only around its dominant frequency. Here, we examined this assumption for ongoing neural oscillations in the alpha-band (8-13 Hz). We found that alpha peak frequency systematically decreased over time, while alpha-power increased. Intriguingly, these systematic changes showed partial independence of each other: Statistical source separation (independent component analysis) revealed that while some alpha components displayed concomitant power increases and peak frequency decreases, other components showed either unique power increases or frequency decreases. Interestingly, we also found these components to differ in frequency. Components that showed mixed frequency/power changes oscillated primarily in the lower alpha-band (∼8-10 Hz), while components with unique changes oscillated primarily in the higher alpha-band (∼9-13 Hz). Our findings provide novel clues on the time-varying intrinsic properties of large-scale neural networks as measured by M/EEG, with implications for the analysis and interpretation of studies that aim at identifying functionally relevant oscillatory networks or at driving them through external stimulation.
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Affiliation(s)
- Christopher S Y Benwell
- Psychology, School of Social Sciences, University of Dundee, Dundee, UK; Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK.
| | - Raquel E London
- Department of Experimental Psychology, Ghent University, 9000, Ghent, Belgium
| | - Chiara F Tagliabue
- CIMEC - Center for Mind/Brain Sciences, Università degli Studi di Trento, Trento, Italy
| | - Domenica Veniero
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Joachim Gross
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK; Institut für Biomagnetismus und Biosignalanalyse, Westfälische Wilhelms-Universität, Malmedyweg 15, 48149, Münster, Germany
| | - Christian Keitel
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
| | - Gregor Thut
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, UK
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214
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Reinhart RMG, Nguyen JA. Working memory revived in older adults by synchronizing rhythmic brain circuits. Nat Neurosci 2019; 22:820-827. [PMID: 30962628 PMCID: PMC6486414 DOI: 10.1038/s41593-019-0371-x] [Citation(s) in RCA: 311] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 02/21/2019] [Indexed: 12/22/2022]
Abstract
Understanding normal brain aging and developing methods to maintain or improve cognition in older adults are major goals of fundamental and translational neuroscience. Here we show a core feature of cognitive decline-working-memory deficits-emerges from disconnected local and long-range circuits instantiated by theta-gamma phase-amplitude coupling in temporal cortex and theta phase synchronization across frontotemporal cortex. We developed a noninvasive stimulation procedure for modulating long-range theta interactions in adults aged 60-76 years. After 25 min of stimulation, frequency-tuned to individual brain network dynamics, we observed a preferential increase in neural synchronization patterns and the return of sender-receiver relationships of information flow within and between frontotemporal regions. The end result was rapid improvement in working-memory performance that outlasted a 50 min post-stimulation period. The results provide insight into the physiological foundations of age-related cognitive impairment and contribute to groundwork for future non-pharmacological interventions targeting aspects of cognitive decline.
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Affiliation(s)
- Robert M G Reinhart
- Department of Psychological & Brain Sciences, Center for Systems Neuroscience, Cognitive Neuroimaging Center, Center for Research in Sensory Communication & Emerging Neural Technology, Boston University, Boston, MA, USA.
| | - John A Nguyen
- Department of Psychological & Brain Sciences, Center for Systems Neuroscience, Cognitive Neuroimaging Center, Center for Research in Sensory Communication & Emerging Neural Technology, Boston University, Boston, MA, USA
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215
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Meier J, Nolte G, Schneider TR, Engel AK, Leicht G, Mulert C. Intrinsic 40Hz-phase asymmetries predict tACS effects during conscious auditory perception. PLoS One 2019; 14:e0213996. [PMID: 30943251 PMCID: PMC6447177 DOI: 10.1371/journal.pone.0213996] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 03/05/2019] [Indexed: 12/31/2022] Open
Abstract
Synchronized oscillatory gamma-band activity (30-100Hz) has been suggested to constitute a key mechanism to dynamically orchestrate sensory information integration across multiple spatio-temporal scales. We here tested whether interhemispheric functional connectivity and ensuing auditory perception can selectively be modulated by high-density transcranial alternating current stimulation (HD-tACS). For this purpose, we applied multi-site HD-tACS at 40Hz bilaterally with a phase lag of 180° and recorded a 64-channel EEG to study the oscillatory phase dynamics at the source-space level during a dichotic listening (DL) task in twenty-six healthy participants. In this study, we revealed an oscillatory phase signature at 40Hz which reflects different temporal profiles of the phase asymmetries during left and right ear percept. Here we report that 180°-tACS did not affect the right ear advantage during DL at group level. However, a follow-up analysis revealed that the intrinsic phase asymmetries during sham-tACS determined the directionality of the behavioral modulations: While a shift to left ear percept was associated with augmented interhemispheric asymmetry (closer to 180°), a shift to right ear processing was elicited in subjects with lower asymmetry (closer to 0°). Crucially, the modulation of the interhemispheric network dynamics depended on the deviation of the tACS-induced phase-lag from the intrinsic phase asymmetry. Our characterization of the oscillatory network trends is giving rise to the importance of phase-specific gamma-band coupling during ambiguous auditory perception, and emphasizes the necessity to address the inter-individual variability of phase asymmetries in future studies by tailored stimulation protocols.
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Affiliation(s)
- Jan Meier
- Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
| | - Guido Nolte
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Till R. Schneider
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas K. Engel
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gregor Leicht
- Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Mulert
- Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Centre for Psychiatry and Psychotherapy, Justus-Liebig-University Giessen, Giessen, Germany
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216
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Lee S, Liu A, Wang ZJ, McKeown MJ. Abnormal Phase Coupling in Parkinson's Disease and Normalization Effects of Subthreshold Vestibular Stimulation. Front Hum Neurosci 2019; 13:118. [PMID: 31001099 PMCID: PMC6456700 DOI: 10.3389/fnhum.2019.00118] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 03/19/2019] [Indexed: 12/14/2022] Open
Abstract
The human brain is a highly dynamic structure requiring dynamic coordination between different neural systems to perform numerous cognitive and behavioral tasks. Emerging perspectives on basal ganglia (BG) and thalamic functions have highlighted their role in facilitating and mediating information transmission among cortical regions. Thus, changes in BG and thalamic structures can induce aberrant modulation of cortico-cortical interactions. Recent work in deep brain stimulation (DBS) has demonstrated that externally applied electrical current to BG structures can have multiple downstream effects in large-scale brain networks. In this work, we identified EEG-based altered resting-state cortical functional connectivity in Parkinson's disease (PD) and examined effects of dopaminergic medication and electrical vestibular stimulation (EVS), a non-invasive brain stimulation (NIBS) technique capable of stimulating the BG and thalamus through vestibular pathways. Resting EEG was collected from 16 PD subjects and 18 age-matched, healthy controls (HC) in four conditions: sham (no stimulation), EVS1 (4-8 Hz multisine), EVS2 (50-100 Hz multisine) and EVS3 (100-150 Hz multisine). The mean, variability, and entropy were extracted from time-varying phase locking value (PLV), a non-linear measure of pairwise functional connectivity, to probe abnormal cortical couplings in the PD subjects. We found the mean PLV of Cz and C3 electrodes were important for discrimination between PD and HC subjects. In addition, the PD subjects exhibited lower variability and entropy of PLV (mostly in theta and alpha bands) compared to the controls, which were correlated with their clinical characteristics. While levodopa medication was effective in normalizing the mean PLV only, all EVS stimuli normalized the mean, variability and entropy of PLV in the PD subject, with the exact extent and duration of improvement a function of stimulus type. These findings provide evidence demonstrating both low- and high-frequency EVS exert widespread influences on cortico-cortical connectivity, likely via subcortical activation. The improvement observed in PD in a stimulus-dependent manner suggests that EVS with optimized parameters may provide a new non-invasive means for neuromodulation of functional brain networks.
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Affiliation(s)
- Soojin Lee
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada.,Pacific Parkinson's Research Centre, Vancouver, BC, Canada
| | - Aiping Liu
- Pacific Parkinson's Research Centre, Vancouver, BC, Canada.,Department of Electronic Science and Technology, University of Science and Technology of China, Hefei, China
| | - Z Jane Wang
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada.,Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Martin J McKeown
- Pacific Parkinson's Research Centre, Vancouver, BC, Canada.,Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada
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217
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Berntsen MB, Cooper NR, Hughes G, Romei V. Prefrontal transcranial alternating current stimulation improves motor sequence reproduction. Behav Brain Res 2019; 361:39-49. [PMID: 30578806 DOI: 10.1016/j.bbr.2018.12.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/01/2018] [Accepted: 12/18/2018] [Indexed: 11/18/2022]
Abstract
Cortical activity in frontal, parietal, and motor regions during sequence observation correlates with performance on sequence reproduction. Increased cortical activity observed during observation has therefore been suggested to represent increased learning. Causal relationships have been demonstrated between M1 and motor sequence reproduction and between parietal cortex and bimanual learning. However, similar effects have not been reported for frontal regions despite a number of reports implicating its involvement in encoding of motor sequences. Investigating causal relations between cortical activity and reproduction of motor sequences in parietal, frontal and primary motor regions can disentangle whether specific regions during simple observation can be selectively ascribed to encoding or reproduction or both. We designed a sensorimotor paradigm that included a strong motor sequence component, and tested the impact of individually adjusted transcranial alternating current stimulation (IAF-tACS) to prefrontal, parietal, and primary motor regions on electroencephalographic motor rhythms (alpha and beta bandwidths) during motor sequence observation and the ability to reproduce the observed sequences. Independently of the stimulated region, IAF-tACS led to a reduction in suppression in the lower beta-range relative to sham. Prefrontal IAF-tACS however, led to significant improvement in motor sequence reproduction, pinpointing the crucial role of prefrontal regions in motor sequence reproduction.
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Affiliation(s)
- Monica B Berntsen
- Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom.
| | - Nicholas R Cooper
- Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom.
| | - Gethin Hughes
- Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom
| | - Vincenzo Romei
- Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom; Dipartimento di Psicologia and Centro Studi e Ricerche in Neuroscienze Cognitive, Campus di Cesena, Universitá di Bologna, 47521 Cesena, Italy
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218
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Roberts BM, Clarke A, Addante RJ, Ranganath C. Entrainment enhances theta oscillations and improves episodic memory. Cogn Neurosci 2019; 9:181-193. [PMID: 30198823 DOI: 10.1080/17588928.2018.1521386] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Neural oscillations in the theta band have been linked to episodic memory, but it is unclear whether activity patterns that give rise to theta play a causal role in episodic retrieval. Here, we used rhythmic auditory and visual stimulation to entrain neural oscillations to assess whether theta activity contributes to successful memory retrieval. In two separate experiments, human subjects studied words and were subsequently tested on memory for the words ('item recognition') and the context in which each had been previously studied ('source memory'). Between study and test, subjects in the entrainment groups were exposed to audiovisual stimuli designed to enhance activity at 5.5 Hz, whereas subjects in the control groups were exposed to white noise (Expt. 1) or 14 Hz entrainment (Expt. 2). Theta entrainment selectively increased source memory performance in both studies. Electroencephalography (EEG) data in Expt. 2 revealed that theta entrainment resulted in band-specific enhancement of theta power during the entrainment period and during post-entrainment memory retrieval. These results demonstrate a direct link between theta activity and episodic memory retrieval. Targeted manipulation of theta activity could be a promising new approach to enhance theta activity and memory performance in healthy individuals and in patients with memory disorders.
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Affiliation(s)
- Brooke M Roberts
- a Department of Psychology , University of California at Davis , Davis , CA , USA
| | - Alex Clarke
- b Department of Psychology , University of Cambridge , Cambridge , UK.,c Department of Psychology , Anglia Ruskin University , Cambridge , UK
| | - Richard J Addante
- d Department of Psychology , California State University , San Bernardino , CA , USA
| | - Charan Ranganath
- a Department of Psychology , University of California at Davis , Davis , CA , USA.,e Center for Neuroscience , University of California at Davis , Davis , CA , USA
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219
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Popp F, Dallmer-Zerbe I, Philipsen A, Herrmann CS. Challenges of P300 Modulation Using Transcranial Alternating Current Stimulation (tACS). Front Psychol 2019; 10:476. [PMID: 30890990 PMCID: PMC6411790 DOI: 10.3389/fpsyg.2019.00476] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 02/18/2019] [Indexed: 11/17/2022] Open
Abstract
The P300 component of the event-related potential (ERP) is a well investigated phenomenon in the human electroencephalogram (EEG) and has been related to stimulus processing and attentional mechanisms. Event-related oscillations (ERO) represent a potential mechanism responsible for generating the ERP. In particular, oscillatory activity in the delta and theta frequency range has been associated with the generation of the P300 component. Transcranial Alternating Current Stimulation (tACS) is capable of modulating oscillatory brain activity in a frequency-specific manner. In this study, we aimed to modulate P300 amplitude using tACS by stimulating the individual ERO involved in the generation of the P300 component. TACS was applied precisely in time to the target P300 occurring in a visual oddball task. In order to achieve an appropriate current distribution, we designed an electrode configuration consisting of two clusters of stimulation electrodes on central-parietal locations. We could not demonstrate a group difference in P300 amplitude after applying tACS in the stimulation condition (N = 17) vs. the sham condition (N = 11). TACS condition and sham condition did not differ regarding their reaction times in response to target stimuli or their event-related spectral perturbation (ERSP) at stimulation frequency. Although a significant influence of stimulation could not yet be revealed on a statistical level, we suggest that the proposed method of using tACS for modulating EROs merits further investigation. Modulation of the P300 component in the ERP could help to gain further insights in the role of EROs generating ERPs and the functional relevance of the P300 component. In this study, we propose a novel approach of applying tACS and provide advice on using tACS for the modulation of EROs.
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Affiliation(s)
- Fabian Popp
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence “Hearing for All”, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Isa Dallmer-Zerbe
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence “Hearing for All”, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Alexandra Philipsen
- Department of Psychiatry and Psychotherapy, Universität of Bonn, Bonn, Germany
| | - Christoph S. Herrmann
- Experimental Psychology Lab, Department of Psychology, European Medical School, Cluster for Excellence “Hearing for All”, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
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220
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Alexander ML, Alagapan S, Lugo CE, Mellin JM, Lustenberger C, Rubinow DR, Fröhlich F. Double-blind, randomized pilot clinical trial targeting alpha oscillations with transcranial alternating current stimulation (tACS) for the treatment of major depressive disorder (MDD). Transl Psychiatry 2019; 9:106. [PMID: 30837453 PMCID: PMC6401041 DOI: 10.1038/s41398-019-0439-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 12/26/2022] Open
Abstract
Major depressive disorder (MDD) is one of the most common psychiatric disorders, but pharmacological treatments are ineffective in a substantial fraction of patients and are accompanied by unwanted side effects. Here we evaluated the feasibility and efficacy of transcranial alternating current stimulation (tACS) at 10 Hz, which we hypothesized would improve clinical symptoms by renormalizing alpha oscillations in the left dorsolateral prefrontal cortex (dlPFC). To this end, 32 participants with MDD were randomized to 1 of 3 arms and received daily 40 min sessions of either 10 Hz-tACS, 40 Hz-tACS, or active sham stimulation for 5 consecutive days. Symptom improvement was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) as the primary outcome. High-density electroencephalograms (hdEEGs) were recorded to measure changes in alpha oscillations as the secondary outcome. For the primary outcome, we did not observe a significant interaction between treatment condition (10 Hz-tACS, 40 Hz-tACS, sham) and session (baseline to 4 weeks after completion of treatment); however, exploratory analyses show that 2 weeks after completion of the intervention, the 10 Hz-tACS group had more responders (MADRS and HDRS) compared with 40 Hz-tACS and sham groups (n = 30, p = 0.026). Concurrently, we found a significant reduction in alpha power over the left frontal regions in EEG after completion of the intervention for the group that received per-protocol 10 Hz-tACS (n = 26, p < 0.05). Our data suggest that targeting oscillations with tACS has potential as a therapeutic intervention for treatment of MDD.
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Affiliation(s)
- Morgan L. Alexander
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA ,0000000122483208grid.10698.36Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Sankaraleengam Alagapan
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA ,0000000122483208grid.10698.36Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Courtney E. Lugo
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Juliann M. Mellin
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA ,0000000122483208grid.10698.36Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Caroline Lustenberger
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA ,0000 0001 2156 2780grid.5801.cNeural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Zurich, 8092 Switzerland
| | - David R. Rubinow
- 0000000122483208grid.10698.36Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA. .,Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA. .,Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA. .,Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA. .,Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA. .,Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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221
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Ahn S, Prim JH, Alexander ML, McCulloch KL, Fröhlich F. Identifying and Engaging Neuronal Oscillations by Transcranial Alternating Current Stimulation in Patients With Chronic Low Back Pain: A Randomized, Crossover, Double-Blind, Sham-Controlled Pilot Study. THE JOURNAL OF PAIN 2019; 20:277.e1-277.e11. [PMID: 30268803 PMCID: PMC6382517 DOI: 10.1016/j.jpain.2018.09.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/23/2018] [Accepted: 09/23/2018] [Indexed: 01/29/2023]
Abstract
Chronic pain is associated with maladaptive reorganization of the central nervous system. Recent studies have suggested that disorganization of large-scale electrical brain activity patterns, such as neuronal network oscillations in the thalamocortical system, plays a key role in the pathophysiology of chronic pain. Yet, little is known about whether and how such network pathologies can be targeted with noninvasive brain stimulation as a nonpharmacological treatment option. We hypothesized that alpha oscillations, a prominent thalamocortical activity pattern in the human brain, are impaired in chronic pain and can be modulated with transcranial alternating current stimulation (tACS). We performed a randomized, crossover, double-blind, sham-controlled study in patients with chronic low back pain (CLBP) to investigate how alpha oscillations relate to pain symptoms for target identification and whether tACS can engage this target and thereby induce pain relief. We used high-density electroencephalography to measure alpha oscillations and found that the oscillation strength in the somatosensory region at baseline before stimulation was negatively correlated with pain symptoms. Stimulation with alpha-tACS compared to sham (placebo) stimulation significantly enhanced alpha oscillations in the somatosensory region. The stimulation-induced increase of alpha oscillations in the somatosensory region was correlated with pain relief. Given these findings of successful target identification and engagement, we propose that modulating alpha oscillations with tACS may represent a target-specific, nonpharmacological treatment approach for CLBP. This trial has been registered in ClinicalTrials.gov (NCT03243084). PERSPECTIVE: This study suggests that a rational design of transcranial alternating current stimulation, which is target identification, engagement, and validation, could be a nonpharmacological treatment approach for patients with CLBP.
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Affiliation(s)
- Sangtae Ahn
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Julianna H Prim
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Morgan L Alexander
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Karen L McCulloch
- Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599..
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222
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Heise KF, Monteiro TS, Leunissen I, Mantini D, Swinnen SP. Distinct online and offline effects of alpha and beta transcranial alternating current stimulation (tACS) on continuous bimanual performance and task-set switching. Sci Rep 2019; 9:3144. [PMID: 30816305 PMCID: PMC6395614 DOI: 10.1038/s41598-019-39900-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/31/2019] [Indexed: 11/09/2022] Open
Abstract
In the present study we examined the effect of bihemispheric in-phase synchronization of motor cortical rhythms on complex bimanual coordination. Twenty young healthy volunteers received 10 Hz or 20 Hz tACS in a double-blind crossover design while performing a bimanual task-set switching paradigm. We used a bilateral high-density montage centred over the hand knob representation within the primary motor cortices to apply tACS time-locked to the switching events. Online tACS in either frequency led to faster but more erroneous switching transitions compared to trials without active stimulation. When comparing stimulation frequencies, 10 Hz stimulation resulted in higher error rates and slower switching transitions than 20 Hz stimulation. Furthermore, the stimulation frequencies showed distinct carry-over effects in trials following stimulation trains. Non-stimulated switching transitions were generally faster but continuous performance became more erroneous over time in the 20 Hz condition. We suggest that the behavioural effects of bifocal in-phase tACS are explained by online synchronization of long-range interhemispheric sensorimotor oscillations, which impacts on interhemispheric information flow and the top-down control required for flexible control of complex bimanual actions. Different stimulation frequencies may lead to distinct offline effects, which potentially accumulate over time and therefore need to be taken into account when evaluating subsequent performance.
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Affiliation(s)
- Kirstin-Friederike Heise
- Research Center for Movement Control and Neuroplasticity, Department of Movement Sciences, KU Leuven, Leuven, Belgium. .,Leuven Brain Institute (LBI), KU Leuven, Leuven, Belgium.
| | - Thiago Santos Monteiro
- Research Center for Movement Control and Neuroplasticity, Department of Movement Sciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute (LBI), KU Leuven, Leuven, Belgium
| | - Inge Leunissen
- Research Center for Movement Control and Neuroplasticity, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Dante Mantini
- Research Center for Movement Control and Neuroplasticity, Department of Movement Sciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute (LBI), KU Leuven, Leuven, Belgium.,Functional Neuroimaging Laboratory, IRCCS San Camillo Hospital, Venice, Italy
| | - Stephan P Swinnen
- Research Center for Movement Control and Neuroplasticity, Department of Movement Sciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute (LBI), KU Leuven, Leuven, Belgium
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223
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Haberbosch L, Schmidt S, Jooss A, Köhn A, Kozarzewski L, Rönnefarth M, Scholz M, Brandt SA. Rebound or Entrainment? The Influence of Alternating Current Stimulation on Individual Alpha. Front Hum Neurosci 2019; 13:43. [PMID: 30809139 PMCID: PMC6380175 DOI: 10.3389/fnhum.2019.00043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 01/25/2019] [Indexed: 01/11/2023] Open
Abstract
Alternating current stimulation (ACS) is an established means to manipulate intrinsic cortical oscillations. While working towards clinical impact, ACS mechanisms of action remain unclear. For ACS’s well-documented influence on occipital alpha, hypotheses include neuronal entrainment as well as rebound phenomena. As a retinal origin is also discussed, we employed a novel form of ACS with the advantage that it specifically targets occipital alpha-oscillations via retinofugal pathways retinofugal ACS (rACS). We aimed to confirm alpha-enhancement outlasting the duration of stimulation with 10 Hz rACS. To distinguish entrainment from rebound effects, we investigated the correlation between alpha peak frequency change and alpha-enhancement strength. We quantified the alpha band power before and after 10 Hz rACS in 15 healthy subjects. Alpha power enhancement and alpha peak frequency change were assessed over the occipital electrodes and compared to sham stimulation. RACS significantly enhanced occipital alpha power in comparison to sham stimulation (p < 0.05). Alpha peak frequency changed by a mean 0.02 Hz (± 0.04). A greater change in alpha peak frequency did not correlate with greater effects on alpha power. Our findings show an alpha-enhancement consistent with studies conducted for transcranial ACS (tACS) and contribute evidence for a retinal involvement in tACS effects on occipital alpha. Furthermore, the lack of correlation between alpha peak frequency change and alpha-enhancement strength provides an argument against entrainment effects and in favor of a rebound phenomenon.
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Affiliation(s)
- Linus Haberbosch
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Sein Schmidt
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Andreas Jooss
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Arvid Köhn
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Leonard Kozarzewski
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Maria Rönnefarth
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Scholz
- Neural Information Processing Group, University of Technology Berlin, Berlin, Germany
| | - Stephan A Brandt
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
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224
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Cabral-Calderin Y, Wilke M. Probing the Link Between Perception and Oscillations: Lessons from Transcranial Alternating Current Stimulation. Neuroscientist 2019; 26:57-73. [PMID: 30730265 PMCID: PMC7003153 DOI: 10.1177/1073858419828646] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Brain oscillations are regarded as important for perception as they open and close time windows for neural spiking to enable the effective communication within and across brain regions. In the past, studies on perception primarily relied on the use of electrophysiological techniques for probing a correlative link between brain oscillations and perception. The emergence of noninvasive brain stimulation techniques such as transcranial alternating current stimulation (tACS) provides the possibility to study the causal contribution of specific oscillatory frequencies to perception. Here, we review the studies on visual, auditory, and somatosensory perception that employed tACS to probe the causality of brain oscillations for perception. The current literature is consistent with a causal role of alpha and gamma oscillations in parieto-occipital regions for visual perception and theta and gamma oscillations in auditory cortices for auditory perception. In addition, the sensory gating by alpha oscillations applies not only to the visual but also to the somatosensory domain. We conclude that albeit more refined perceptual paradigms and individualized stimulation practices remain to be systematically adopted, tACS is a promising tool for establishing a causal link between neural oscillations and perception.
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Affiliation(s)
- Yuranny Cabral-Calderin
- MEG Unit, Brain Imaging Center, Goethe University Frankfurt, Frankfurt am Main, Germany.,German Resilience Center, University Medical Center Mainz, Mainz, Germany
| | - Melanie Wilke
- Department of Cognitive Neurology, University Medicine Göttingen, Göttingen, Germany.,German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany.,DFG Center for Nanoscale Microscopy & Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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225
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Huang G, Liu J, Li L, Zhang L, Zeng Y, Ren L, Ye S, Zhang Z. A novel training-free externally-regulated neurofeedback (ER-NF) system using phase-guided visual stimulation for alpha modulation. Neuroimage 2019; 189:688-699. [PMID: 30711469 DOI: 10.1016/j.neuroimage.2019.01.072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 12/31/2018] [Accepted: 01/29/2019] [Indexed: 12/28/2022] Open
Abstract
The efficacy of neurofeedback is a point of great controversy, because a certain proportion of users cannot properly regulate their brain activities and thereby fail to benefit from neurofeedback. To address the neurofeedback inefficacy problem, the present study is aimed to design and implement a new neurofeedback system that can more effectively and consistently regulate users' brain activities than the conventional way of training users to voluntarily regulate brain activities. The new neurofeedback system delivers external visual stimuli continuously at a specific alpha phase, which is real-time decoded from ongoing alpha wave, to regulate the alpha wave. Experimental results show that the proposed training-free externally-regulated neurofeedback (ER-NF) system can achieve consistent (effective in almost all sessions for almost all users), flexible (either increasing or decreasing peak alpha frequency and alpha power), and immediate (taking or losing effect immediately after stimulation is on or off) modulation effects on alpha wave. Therefore, the ER-NF system holds great potential to be able to more reliably and flexibly modulate cognition and behavior.
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Affiliation(s)
- Gan Huang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen, 518060, China
| | - Jia Liu
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen, 518060, China
| | - Linling Li
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen, 518060, China
| | - Li Zhang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen, 518060, China
| | - Yixuan Zeng
- Department of Neurology, Shenzhen Second People's Hospital, Shenzhen University 1st Affiliated Hospital, Shenzhen, 518029, China
| | - Lijie Ren
- Department of Neurology, Shenzhen Second People's Hospital, Shenzhen University 1st Affiliated Hospital, Shenzhen, 518029, China
| | - Shiqing Ye
- School of Information Science and Technology, Fudan University, Shanghai, 200433, China
| | - Zhiguo Zhang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, 518060, China; Guangdong Provincial Key Laboratory of Biomedical Measurements and Ultrasound Imaging, Shenzhen, 518060, China.
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226
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Asamoah B, Khatoun A, Mc Laughlin M. tACS motor system effects can be caused by transcutaneous stimulation of peripheral nerves. Nat Commun 2019; 10:266. [PMID: 30655523 PMCID: PMC6336776 DOI: 10.1038/s41467-018-08183-w] [Citation(s) in RCA: 151] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 12/19/2018] [Indexed: 01/19/2023] Open
Abstract
Transcranial alternating current stimulation (tACS) is a noninvasive neuromodulation method which has been shown to modulate hearing, motor, cognitive and memory function. However, the mechanisms underpinning these findings are controversial, as studies show that the current reaching the cortex may not be strong enough to entrain neural activity. Here, we propose a new hypothesis to reconcile these opposing results: tACS effects are caused by transcutaneous stimulation of peripheral nerves in the skin and not transcranial stimulation of cortical neurons. Rhythmic activity from peripheral nerves then entrains cortical neurons. A series of experiments in rats and humans isolated the transcranial and transcutaneous mechanisms and showed that the reported effects of tACS on the motor system can be caused by transcutaneous stimulation of peripheral nerves. Whether or not the transcutaneous mechanism will generalize to tACS effects on other systems is debatable but should be investigated. Transcranial alternating current stimulation (tACS) uses weak electrical currents, applied to the head, to modulate brain activity. Here, the authors show that contrary to previous assumptions, the effects of tACS on the brain may be mediated by its effect on peripheral nerves in the skin, not direct.
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Affiliation(s)
- Boateng Asamoah
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium
| | - Ahmad Khatoun
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium
| | - Myles Mc Laughlin
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium.
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227
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Kohli S, Casson AJ. Removal of Gross Artifacts of Transcranial Alternating Current Stimulation in Simultaneous EEG Monitoring. SENSORS 2019; 19:s19010190. [PMID: 30621077 PMCID: PMC6338981 DOI: 10.3390/s19010190] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/08/2018] [Accepted: 01/02/2019] [Indexed: 01/24/2023]
Abstract
Transcranial electrical stimulation is a widely used non-invasive brain stimulation approach. To date, EEG has been used to evaluate the effect of transcranial Direct Current Stimulation (tDCS) and transcranial Alternating Current Stimulation (tACS), but most studies have been limited to exploring changes in EEG before and after stimulation due to the presence of stimulation artifacts in the EEG data. This paper presents two different algorithms for removing the gross tACS artifact from simultaneous EEG recordings. These give different trade-offs in removal performance, in the amount of data required, and in their suitability for closed loop systems. Superposition of Moving Averages and Adaptive Filtering techniques are investigated, with significant emphasis on verification. We present head phantom testing results for controlled analysis, together with on-person EEG recordings in the time domain, frequency domain, and Event Related Potential (ERP) domain. The results show that EEG during tACS can be recovered free of large scale stimulation artifacts. Previous studies have not quantified the performance of the tACS artifact removal procedures, instead focusing on the removal of second order artifacts such as respiration related oscillations. We focus on the unresolved challenge of removing the first order stimulation artifact, presented with a new multi-stage validation strategy.
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Affiliation(s)
- Siddharth Kohli
- School of Electrical and Electronic Engineering, The University of Manchester, Manchester M13 9PL, UK.
| | - Alexander J Casson
- School of Electrical and Electronic Engineering, The University of Manchester, Manchester M13 9PL, UK.
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228
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Craddock M, Klepousniotou E, El-Deredy W, Poliakoff E, Lloyd D. Transcranial alternating current stimulation at 10 Hz modulates response bias in the Somatic Signal Detection Task. Int J Psychophysiol 2019; 135:106-112. [PMID: 30528832 PMCID: PMC6327150 DOI: 10.1016/j.ijpsycho.2018.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 12/01/2022]
Abstract
Ongoing, pre-stimulus oscillatory activity in the 8-13 Hz alpha range has been shown to correlate with both true and false reports of peri-threshold somatosensory stimuli. However, to directly test the role of such oscillatory activity in behaviour, it is necessary to manipulate it. Transcranial alternating current stimulation (tACS) offers a method of directly manipulating oscillatory brain activity using a sinusoidal current passed to the scalp. We tested whether alpha tACS would change somatosensory sensitivity or response bias in a signal detection task in order to test whether alpha oscillations have a causal role in behaviour. Active 10 Hz tACS or sham stimulation was applied using electrodes placed bilaterally at positions CP3 and CP4 of the 10-20 electrode placement system. Participants performed the Somatic Signal Detection Task (SSDT), in which they must detect brief somatosensory targets delivered at their detection threshold. These targets are sometimes accompanied by a light flash, which could also occur alone. Active tACS did not modulate sensitivity to targets but did modulate response criterion. Specifically, we found that active stimulation generally increased touch reporting rates, but particularly increased responding on light trials. Stimulation did not interact with the presence of touch, and thus increased both hits and false alarms. TACS stimulation increased reports of touch in a manner consistent with our observational reports, changing response bias, and consistent with a role for alpha activity in somatosensory detection.
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Affiliation(s)
- Matt Craddock
- School of Psychology, University of Lincoln, LN6 7TS, UK
| | | | - Wael El-Deredy
- Centro de Investigación y Desarrollo en Ingeniería en Salud, Universidad de Valparaiso, Chile
| | - Ellen Poliakoff
- Division of Neuroscience and Experimental Psychology, University of Manchester, M13 9PL, UK
| | - Donna Lloyd
- School of Psychology, University of Leeds, Leeds LS2 9JT, UK.
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229
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Alagapan S, Lustenberger C, Hadar E, Shin HW, Frӧhlich F. Low-frequency direct cortical stimulation of left superior frontal gyrus enhances working memory performance. Neuroimage 2019; 184:697-706. [PMID: 30268847 PMCID: PMC6240347 DOI: 10.1016/j.neuroimage.2018.09.064] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/02/2018] [Accepted: 09/21/2018] [Indexed: 02/02/2023] Open
Abstract
The neural substrates of working memory are spread across prefrontal, parietal and cingulate cortices and are thought to be coordinated through low frequency cortical oscillations in the theta (3-8 Hz) and alpha (8-12 Hz) frequency bands. While the functional role of many subregions have been elucidated using neuroimaging studies, the role of superior frontal gyrus (SFG) is not yet clear. Here, we combined electrocorticography and direct cortical stimulation in three patients implanted with subdural electrodes to assess if superior frontal gyrus is indeed involved in working memory. We found left SFG exhibited task-related modulation of oscillations in the theta and alpha frequency bands specifically during the encoding epoch. Stimulation at the frequency matched to the endogenous oscillations resulted in reduced reaction times in all three participants. Our results provide evidence for SFG playing a functional role in working memory and suggest that SFG may coordinate working memory through low-frequency oscillations thus bolstering the feasibility of using intracranial electric stimulation for restoring cognitive function.
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Affiliation(s)
- Sankaraleengam Alagapan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Caroline Lustenberger
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Eldad Hadar
- Department of Neurosurgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Hae Won Shin
- Department of Neurosurgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Flavio Frӧhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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230
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Anodal transcranial patterned stimulation of the motor cortex during gait can induce activity-dependent corticospinal plasticity to alter human gait. PLoS One 2018; 13:e0208691. [PMID: 30576315 PMCID: PMC6303011 DOI: 10.1371/journal.pone.0208691] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 11/22/2018] [Indexed: 12/22/2022] Open
Abstract
The corticospinal system and local spinal circuits control human bipedal locomotion. The primary motor cortex is phase-dependently activated during gait; this cortical input is critical for foot flexor activity during the swing phase. We investigated whether gait-combined rhythmic brain stimulation can induce neuroplasticity in the foot area of the motor cortex and alter gait parameters. Twenty-one healthy subjects participated in the single-blinded, cross-over study. Each subject received anodal transcranial patterned direct current stimulation over the foot area of the right motor cortex during gait, sham stimulation during gait, and anodal transcranial patterned direct current stimulation during rest in a random order. Six subjects were excluded due to a failure in the experimental recording procedure. Complete-case analysis was performed using the data from the remaining 15 subjects. Self-paced gait speed and left leg stride length were significantly increased after the stimulation during gait, but not after the sham stimulation during gait or the stimulation during rest. In addition, a significant increase was found in the excitability of the corticospinal pathway of the left tibialis anterior muscle 30 min after stimulation during gait. Anodal transcranial patterned direct current stimulation during gait entrained the gait cycle to enhance motor cortical activity in some subjects. These findings suggest that the stimulation during gait induced neuroplasticity in corticospinal pathways driving flexor muscles during gait.
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231
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Widge AS, Boggess M, Rockhill AP, Mullen A, Sheopory S, Loonis R, Freeman DK, Miller EK. Altering alpha-frequency brain oscillations with rapid analog feedback-driven neurostimulation. PLoS One 2018; 13:e0207781. [PMID: 30517149 PMCID: PMC6281199 DOI: 10.1371/journal.pone.0207781] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 11/06/2018] [Indexed: 01/11/2023] Open
Abstract
Oscillations of the brain's local field potential (LFP) may coordinate neural ensembles and brain networks. It has been difficult to causally test this model or to translate its implications into treatments, because there are few reliable ways to alter LFP oscillations. We developed a closed-loop analog circuit to enhance brain oscillations by feeding them back into cortex through phase-locked transcranial electrical stimulation. We tested the system in a rhesus macaque with chronically implanted electrode arrays, targeting 8-15 Hz (alpha) oscillations. Ten seconds of stimulation increased alpha oscillatory power for up to 1 second after stimulation offset. In contrast, open-loop stimulation decreased alpha power. There was no effect in the neighboring 15-30 Hz (beta) LFP rhythm or on a neighboring array that did not participate in closed-loop feedback. Analog closed-loop neurostimulation might thus be a useful strategy for altering brain oscillations, both for basic research and the treatment of neuro-psychiatric disease.
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Affiliation(s)
- Alik S. Widge
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Matthew Boggess
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alexander P. Rockhill
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Andrew Mullen
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Shivani Sheopory
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- College of Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Roman Loonis
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Daniel K. Freeman
- The Charles Stark Draper Laboratory, Inc., Cambridge, Massachusetts, United States of America
| | - Earl K. Miller
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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232
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Mansouri F, Fettes P, Schulze L, Giacobbe P, Zariffa J, Downar J. A Real-Time Phase-Locking System for Non-invasive Brain Stimulation. Front Neurosci 2018; 12:877. [PMID: 30559641 PMCID: PMC6287008 DOI: 10.3389/fnins.2018.00877] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 11/12/2018] [Indexed: 12/16/2022] Open
Abstract
Non-invasive brain stimulation techniques are entering widespread use for the investigation and treatment of a range of neurological and neuropsychiatric disorders. However, most current techniques are ‘open-loop’, without feedback from target brain region activity; this limitation could contribute to heterogeneous effects seen for nominally ‘inhibitory’ and ‘excitatory’ protocols across individuals. More potent and consistent effects may ensue from closed-loop and, in particular, phase-locked brain stimulation. In this work, a closed-loop brain stimulation system is introduced that can analyze EEG data in real-time, provide a forecast of the phase of an underlying brain rhythm of interest, and control pulsed transcranial electromagnetic stimulation to deliver pulses at a specific phase of the target frequency band. The technique was implemented using readily available equipment such as a basic EEG system, a low-cost Arduino board and MATLAB scripts. The phase-locked brain stimulation method was tested in 5 healthy volunteers and its phase-locking performance evaluated at 0, 90, 180, and 270 degree phases in theta and alpha frequency bands. On average phase locking values of 0.55° ± 0.11° and 0.52° ± 0.14° and error angles of 11° ± 11° and 3.3° ± 18° were achieved for theta and alpha stimulation, respectively. Despite the low-cost hardware implementation, signal processing time generated a phase delay of only 3.8° for theta and 57° for alpha stimulation, both readily accommodated in the pulse trigger algorithm. This work lays the methodological steps for achieving phase-locked brain stimulation for brief-pulse transcranial electrical stimulation (tES) and repetitive transcranial magnetic stimulation (rTMS), facilitating further research on the effect of stimulation phase for these techniques.
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Affiliation(s)
- Farrokh Mansouri
- Institute of Biomaterial and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Peter Fettes
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Laura Schulze
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Peter Giacobbe
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada.,Centre for Mental Health, University Health Network, Toronto, ON, Canada.,Harquail Centre for Neuromodulation, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Jose Zariffa
- Institute of Biomaterial and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.,Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada
| | - Jonathan Downar
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada.,Centre for Mental Health, University Health Network, Toronto, ON, Canada.,Krembil Research Institute, University Health Network, Toronto, ON, Canada
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233
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Sliva DD, Black CJ, Bowary P, Agrawal U, Santoyo JF, Philip NS, Greenberg BD, Moore CI, Jones SR. A Prospective Study of the Impact of Transcranial Alternating Current Stimulation on EEG Correlates of Somatosensory Perception. Front Psychol 2018; 9:2117. [PMID: 30515114 PMCID: PMC6255923 DOI: 10.3389/fpsyg.2018.02117] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/15/2018] [Indexed: 01/30/2023] Open
Abstract
The (8-12 Hz) neocortical alpha rhythm is associated with shifts in attention across sensory systems, and is thought to represent a sensory gating mechanism for the inhibitory control of cortical processing. The present preliminary study sought to explore whether alpha frequency transcranial alternating current stimulation (tACS) could modulate endogenous alpha power in the somatosensory system, and whether the hypothesized modulation would causally impact perception of tactile stimuli at perceptual threshold. We combined electroencephalography (EEG) with simultaneous brief and intermittent tACS applied over primary somatosensory cortex at individuals' endogenous alpha frequency during a tactile detection task (n = 12 for EEG, n = 20 for behavior). EEG-measured pre-stimulus alpha power was higher on non-perceived than perceived trials, and analogous perceptual correlates emerged in early components of the tactile evoked response. Further, baseline normalized tactile detection performance was significantly lower during alpha than sham tACS, but the effect did not last into the post-tACS time period. Pre- to post-tACS changes in alpha power were linearly dependent upon baseline state, such that alpha power tended to increase when pre-tACS alpha power was low, and decrease when it was high. However, these observations were comparable in both groups, and not associated with evidence of tACS-induced alpha power modulation. Nevertheless, the tactile stimulus evoked response potential (ERP) revealed a potentially lasting impact of alpha tACS on circuit dynamics. The post-tACS ERP was marked by the emergence of a prominent peak ∼70 ms post-stimulus, which was not discernible post-sham, or in either pre-stimulation condition. Computational neural modeling designed to simulate macroscale EEG signals supported the hypothesis that the emergence of this peak could reflect synaptic plasticity mechanisms induced by tACS. The primary lesson learned in this study, which commanded a small sample size, was that while our experimental paradigm provided some evidence of an influence of tACS on behavior and circuit dynamics, it was not sufficient to induce observable causal effects of tACS on EEG-measured alpha oscillations. We discuss limitations and suggest improvements that may help further delineate a causal influence of tACS on cortical dynamics and perception in future studies.
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Affiliation(s)
- Danielle D. Sliva
- Department of Neuroscience, Brown University, Providence, RI, United States
| | - Christopher J. Black
- Department of Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Paul Bowary
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | - Uday Agrawal
- Harvard Medical School, Boston, MA, United States
| | - Juan F. Santoyo
- Department of Neuroscience, Brown University, Providence, RI, United States
| | - Noah S. Philip
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | - Benjamin D. Greenberg
- Department of Psychiatry and Human Behavior, Brown University Medical School, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
- Butler Hospital, Providence, RI, United States
| | | | - Stephanie R. Jones
- Department of Neuroscience, Brown University, Providence, RI, United States
- Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI, United States
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234
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Modulation of Motor Learning Capacity by Transcranial Alternating Current Stimulation. Neuroscience 2018; 391:131-139. [DOI: 10.1016/j.neuroscience.2018.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/05/2018] [Accepted: 09/10/2018] [Indexed: 11/18/2022]
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235
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Ahn S, Mellin JM, Alagapan S, Alexander ML, Gilmore JH, Jarskog LF, Fröhlich F. Targeting reduced neural oscillations in patients with schizophrenia by transcranial alternating current stimulation. Neuroimage 2018; 186:126-136. [PMID: 30367952 DOI: 10.1016/j.neuroimage.2018.10.056] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 10/01/2018] [Accepted: 10/21/2018] [Indexed: 12/28/2022] Open
Abstract
Transcranial alternating current stimulation (tACS) modulates endogenous neural oscillations in healthy human participants by the application of a low-amplitude electrical current with a periodic stimulation waveform. Yet, it is unclear if tACS can modulate and restore neural oscillations that are reduced in patients with psychiatric illnesses such as schizophrenia. Here, we asked if tACS modulates network oscillations in schizophrenia. We performed a randomized, double-blind, sham-controlled clinical trial to contrast tACS with transcranial direct current stimulation (tDCS) and sham stimulation in 22 schizophrenia patients with auditory hallucinations. We used high-density electroencephalography to investigate if a five-day, twice-daily 10Hz-tACS protocol enhances alpha oscillations and modulates network dynamics that are reduced in schizophrenia. We found that 10Hz-tACS enhanced alpha oscillations and modulated functional connectivity in the alpha frequency band. In addition, 10Hz-tACS enhanced the 40Hz auditory steady-state response (ASSR), which is reduced in patients with schizophrenia. Importantly, clinical improvement of auditory hallucinations correlated with enhancement of alpha oscillations and the 40Hz-ASSR. Together, our findings suggest that tACS has potential as a network-level approach to modulate reduced neural oscillations related to clinical symptoms in patients with schizophrenia.
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Affiliation(s)
- Sangtae Ahn
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States
| | - Juliann M Mellin
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States
| | - Sankaraleengam Alagapan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States
| | - Morgan L Alexander
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States
| | - John H Gilmore
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States
| | - L Fredrik Jarskog
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; North Carolina Psychiatric Research Center, Raleigh, NC, 27610, United States
| | - Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, United States.
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236
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No Modulatory Effects when Stimulating the Right Inferior Frontal Gyrus with Continuous 6 Hz tACS and tRNS on Response Inhibition: A Behavioral Study. Neural Plast 2018; 2018:3156796. [PMID: 30425735 PMCID: PMC6218719 DOI: 10.1155/2018/3156796] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 08/07/2018] [Accepted: 08/19/2018] [Indexed: 12/12/2022] Open
Abstract
Response inhibition is the cognitive process required to cancel an intended action. During that process, a “go” reaction is intercepted particularly by the right inferior frontal gyrus (rIFG) and presupplementary motor area (pre-SMA). After the commission of inhibition errors, theta activity (4–8 Hz) is related to the adaption processes. In this study, we intend to examine whether the boosting of theta activity by electrical stimulation over rIFG reduces the number of errors and the reaction times in a response inhibition task (Go/NoGo paradigm) during and after stimulation. 23 healthy right-handed adults participated in the study. In three separate sessions, theta tACS at 6 Hz, transcranial random noise (tRNS) as a second stimulation condition, and sham stimulation were applied for 20 minutes. Based on behavioral data, this study could not show any effects of 6 Hz tACS as well as full spectrum tRNS on response inhibition in any of the conditions. Since many findings support the relevance of the rIFG for response inhibition, this could mean that 6 Hz activity is not important for response inhibition in that structure. Reasons for our null findings could also lie in the stimulation parameters, such as the electrode montage or the stimulation frequency, which are discussed in this article in more detail. Sharing negative findings will have (1) positive impact on future research questions and study design and will improve (2) knowledge acquisition of noninvasive transcranial brain stimulation techniques.
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237
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Stecher HI, Herrmann CS. Corrigendum: Absence of Alpha-tACS Aftereffects in Darkness Reveals Importance of Taking Derivations of Stimulation Frequency and Individual Alpha Variability Into Account. Front Psychol 2018; 9:1769. [PMID: 30271369 PMCID: PMC6157486 DOI: 10.3389/fpsyg.2018.01769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/03/2018] [Indexed: 12/02/2022] Open
Affiliation(s)
- 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.,Research Center Neurosensory Science, Carl von Ossietzky University, Oldenburg, Germany
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238
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Non-linear transfer characteristics of stimulation and recording hardware account for spurious low-frequency artifacts during amplitude modulated transcranial alternating current stimulation (AM-tACS). Neuroimage 2018; 179:134-143. [DOI: 10.1016/j.neuroimage.2018.05.068] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/25/2018] [Accepted: 05/28/2018] [Indexed: 01/01/2023] Open
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239
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Sasaki R, Tsuiki S, Miyaguchi S, Kojima S, Saito K, Inukai Y, Otsuru N, Onishi H. Repetitive Passive Finger Movement Modulates Primary Somatosensory Cortex Excitability. Front Hum Neurosci 2018; 12:332. [PMID: 30177877 PMCID: PMC6109762 DOI: 10.3389/fnhum.2018.00332] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 07/30/2018] [Indexed: 11/13/2022] Open
Abstract
Somatosensory inputs induced by repetitive passive movement (RPM) modulate primary motor cortex (M1) excitability; however, it is unclear whether RPM affects primary somatosensory cortex (S1) excitability. In this study, we investigated whether RPM affects somatosensory evoked potentials (SEPs) and resting state brain oscillation, including alpha and beta bands, depend on RPM frequency. Nineteen healthy subjects participated in this study, and SEPs elicited by peripheral nerve electrical stimulation were recorded from the C3’ area in order to assess S1 excitability (Exp. 1: n = 15). We focused on prominent SEP components such as N20, P25 and P45-reflecting S1 activities. In addition, resting electroencephalograms (EEGs) were recorded from C3’ area to assess the internal state of the brain network at rest (Exp. 2: n = 15). Passive abduction/adduction of the right index finger was applied for 10 min at frequencies of 0.5, 1.0, 3.0, and 5.0 Hz in Exp. 1, and 1.0, 3.0, and 5.0 Hz in Exp. 2. No changes in N20 or P25 components were observed following RPM. The 3.0 Hz-RPM decreased the P45 component for 20 min (p < 0.05), but otherwise did not affect the P45 component. There was no difference in the alpha and beta bands before and after any RPM; however, a negative correlation was observed between the rate of change of beta power and P45 component at 3.0 Hz-RPM. Our findings indicated that the P45 component changes depending on the RPM frequency, suggesting that somatosensory inputs induced by RPM influences S1 excitability. Additionally, beta power enhancement appears to contribute to the P45 component depression in 3.0 Hz-RPM.
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Affiliation(s)
- Ryoki Sasaki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Shota Tsuiki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Shota Miyaguchi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Sho Kojima
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Kei Saito
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Yasuto Inukai
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Naofumi Otsuru
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Hideaki Onishi
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
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240
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Manuel AL, Guggisberg AG, Thézé R, Turri F, Schnider A. Resting-state connectivity predicts visuo-motor skill learning. Neuroimage 2018; 176:446-453. [DOI: 10.1016/j.neuroimage.2018.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/30/2018] [Accepted: 05/01/2018] [Indexed: 02/06/2023] Open
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241
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Facilitated Event-Related Power Modulations during Transcranial Alternating Current Stimulation (tACS) Revealed by Concurrent tACS-MEG. eNeuro 2018; 5:eN-TNWR-0069-18. [PMID: 30073188 PMCID: PMC6070188 DOI: 10.1523/eneuro.0069-18.2018] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/01/2018] [Accepted: 06/07/2018] [Indexed: 01/02/2023] Open
Abstract
Non-invasive approaches to modulate oscillatory activity in the brain are increasingly popular in the scientific community. Transcranial alternating current stimulation (tACS) has been shown to modulate neural oscillations in a frequency-specific manner. However, due to a massive stimulation artifact at the targeted frequency, little is known about effects of tACS during stimulation. It remains unclear how the continuous application of tACS affects event-related oscillations during cognitive tasks. Depending on whether tACS influences pre- or post-stimulus oscillations, or both, the endogenous, event-related oscillatory dynamics could be pushed in various directions or not at all. A better understanding of these effects is crucial to plan, predict, and understand outcomes of solely behavioral tACS experiments. In the present study, a recently proposed procedure to suppress tACS artifacts by projecting MEG data into source-space using spatial filtering was utilized to recover event-related power modulations in the alpha-band during a mental rotation task. MEG data of 25 human subjects was continuously recorded. After 10-minute baseline measurement, participants received either 20 minutes of tACS at their individual alpha frequency or sham stimulation. Another 40 minutes of MEG data were acquired thereafter. Data were projected into source-space and carefully examined for residual artifacts. Results revealed strong facilitation of event-related power modulations in the alpha-band during tACS application. These results provide first direct evidence that tACS does not counteract top-down suppression of intrinsic oscillations, but rather enhances pre-existent power modulations within the range of the individual alpha (= stimulation) frequency.
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242
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Arendsen LJ, Hugh-Jones S, Lloyd DM. Transcranial Alternating Current Stimulation at Alpha Frequency Reduces Pain When the Intensity of Pain is Uncertain. THE JOURNAL OF PAIN 2018; 19:807-818. [DOI: 10.1016/j.jpain.2018.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 01/15/2018] [Accepted: 02/22/2018] [Indexed: 12/31/2022]
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243
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Fresnoza S, Christova M, Feil T, Gallasch E, Körner C, Zimmer U, Ischebeck A. The effects of transcranial alternating current stimulation (tACS) at individual alpha peak frequency (iAPF) on motor cortex excitability in young and elderly adults. Exp Brain Res 2018; 236:2573-2588. [PMID: 29943239 PMCID: PMC6153871 DOI: 10.1007/s00221-018-5314-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 06/14/2018] [Indexed: 11/28/2022]
Abstract
Transcranial alternating current stimulation (tACS) can modulate brain oscillations, cortical excitability and behaviour. In aging, the decrease in EEG alpha activity (8–12 Hz) in the parieto-occipital and mu rhythm in the motor cortex are correlated with the decline in cognitive and motor functions, respectively. Increasing alpha activity using tACS might therefore improve cognitive and motor function in the elderly. The present study explored the influence of tACS on cortical excitability in young and old healthy adults. We applied tACS at individual alpha peak frequency for 10 min (1.5 mA) to the left motor cortex. Transcranial magnetic stimulation was used to assess the changes in cortical excitability as measured by motor-evoked potentials at rest, before and after stimulation. TACS increased cortical excitability in both groups. However, our results also suggest that the mechanism behind the effects was different, as we observed an increase and decrease in intracortical inhibition in the old group and young group, respectively. Our results indicate that both groups profited similarly from the stimulation. There was no indication that tACS was more effective in conditions of low alpha power, that is, in the elderly.
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Affiliation(s)
- Shane Fresnoza
- Institute of Psychology, University of Graz, Graz, Austria. .,Institute of Physiology, Medical University of Graz, Graz, Austria.
| | - Monica Christova
- Otto Loewi Research Center, Physiology Section, Medical University of Graz, Graz, Austria.,Department of Physiotherapy, University of Applied Sciences FH-Joanneum Graz, Graz, Austria
| | - Theresa Feil
- Institute of Psychology, University of Graz, Graz, Austria
| | - Eugen Gallasch
- Institute of Physiology, Medical University of Graz, Graz, Austria.,BioTechMed, Graz, Austria
| | - Christof Körner
- Institute of Psychology, University of Graz, Graz, Austria.,BioTechMed, Graz, Austria
| | - Ulrike Zimmer
- Institute of Psychology, University of Graz, Graz, Austria.,Faculty of Human Sciences, Medical School Hamburg (MSH), Hamburg, Germany
| | - Anja Ischebeck
- Institute of Psychology, University of Graz, Graz, Austria.,BioTechMed, Graz, Austria
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244
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Stecher HI, Herrmann CS. Absence of Alpha-tACS Aftereffects in Darkness Reveals Importance of Taking Derivations of Stimulation Frequency and Individual Alpha Variability Into Account. Front Psychol 2018; 9:984. [PMID: 29973896 PMCID: PMC6019480 DOI: 10.3389/fpsyg.2018.00984] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/28/2018] [Indexed: 11/13/2022] Open
Abstract
Transcranial alternating current stimulation (tACS) has found widespread use as a basic tool in the exploration of the role of brain oscillations. Many studies have shown that frequency-specific tACS is able to not only alter cognitive processes during stimulation, but also cause specific physiological aftereffects visible in the electroencephalogram (EEG). The relationship between the emergence of these aftereffects and the necessary duration of stimulation is inconclusive. Our goal in this study was to narrow down the crucial length of tACS-blocks, by which aftereffects can be elicited. We stimulated participants with α-tACS in four blocks of 1-, 3-, 5-, and 10-min length, once in increasing and once in decreasing order. After each block, we measured the resting EEG for 10 min during a visual vigilance task. We could not find lasting enhancement of α-power following any stimulation block, when comparing the stimulated groups to the sham group. These findings offer no information regarding the crucial stimulation duration. In addition, this conflicts with previous findings, showing a power increase following 10 min of tACS in the alpha range. We performed additional explorative analyses, based on known confounds of (1) mismatches between stimulation frequency and individual alpha frequency and (2) abnormalities in baseline α-activity. The results of an ANCOVA suggested that both factor explain variance, but could not resolve how exactly both factors interfere with the stimulation effect. Employing a linear mixed model, we found a significant effect of stimulation following 10 min of α-tACS in the increasing sequence and a significant effect of the mismatch between stimulated frequency and individual alpha frequency. The implications of these findings for future research are discussed.
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Affiliation(s)
- 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.,Research Center Neurosensory Science, Carl von Ossietzky University, Oldenburg, Germany
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245
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Ros T, Frewen P, Théberge J, Michela A, Kluetsch R, Mueller A, Candrian G, Jetly R, Vuilleumier P, Lanius RA. Neurofeedback Tunes Scale-Free Dynamics in Spontaneous Brain Activity. Cereb Cortex 2018; 27:4911-4922. [PMID: 27620975 DOI: 10.1093/cercor/bhw285] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
Abstract
Brain oscillations exhibit long-range temporal correlations (LRTCs), which reflect the regularity of their fluctuations: low values representing more random (decorrelated) while high values more persistent (correlated) dynamics. LRTCs constitute supporting evidence that the brain operates near criticality, a state where neuronal activities are balanced between order and randomness. Here, healthy adults used closed-loop brain training (neurofeedback, NFB) to reduce the amplitude of alpha oscillations, producing a significant increase in spontaneous LRTCs post-training. This effect was reproduced in patients with post-traumatic stress disorder, where abnormally random dynamics were reversed by NFB, correlating with significant improvements in hyperarousal. Notably, regions manifesting abnormally low LRTCs (i.e., excessive randomness) normalized toward healthy population levels, consistent with theoretical predictions about self-organized criticality. Hence, when exposed to appropriate training, spontaneous cortical activity reveals a residual capacity for "self-tuning" its own temporal complexity, despite manifesting the abnormal dynamics seen in individuals with psychiatric disorder. Lastly, we observed an inverse-U relationship between strength of LRTC and oscillation amplitude, suggesting a breakdown of long-range dependence at high/low synchronization extremes, in line with recent computational models. Together, our findings offer a broader mechanistic framework for motivating research and clinical applications of NFB, encompassing disorders with perturbed LRTCs.
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Affiliation(s)
- T Ros
- Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland
| | - P Frewen
- Department of Psychiatry, Western University, London N6A 5A5, Ontario, Canada
| | - J Théberge
- Department of Medical Imaging, Lawson Health Research Institute, London N6C 2R5, Ontario, Canada
| | - A Michela
- Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland
| | - R Kluetsch
- Department of Psychosomatic Medicine and Psychotherapy, Mannheim-Heidelberg University, 68159 Mannheim, Germany
| | - A Mueller
- Brain and Trauma Foundation, CH-7000 Chur, Switzerland
| | - G Candrian
- Brain and Trauma Foundation, CH-7000 Chur, Switzerland
| | - R Jetly
- Directorate of Mental Health, Canadian Forces Health Services, Ottawa K1A 0K6, Canada
| | - P Vuilleumier
- Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland
| | - R A Lanius
- Department of Psychiatry, Western University, London N6A 5A5, Ontario, Canada
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246
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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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247
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Baltus A, Vosskuhl J, Boetzel C, Herrmann CS. Transcranial alternating current stimulation modulates auditory temporal resolution in elderly people. Eur J Neurosci 2018; 51:1328-1338. [PMID: 29754449 DOI: 10.1111/ejn.13940] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 03/23/2018] [Indexed: 11/28/2022]
Abstract
Recent research provides evidence for a functional role of brain oscillations for perception. For example, auditory temporal resolution seems to be linked to individual gamma frequency of auditory cortex. Individual gamma frequency not only correlates with performance in between-channel gap detection tasks but can be modulated via auditory transcranial alternating current stimulation. Modulation of individual gamma frequency is accompanied by an improvement in gap detection performance. Aging changes electrophysiological frequency components and sensory processing mechanisms. Therefore, we conducted a study to investigate the link between individual gamma frequency and gap detection performance in elderly people using auditory transcranial alternating current stimulation. In a within-subject design, twelve participants were electrically stimulated with two individualized transcranial alternating current stimulation frequencies: 3 Hz above their individual gamma frequency (experimental condition) and 4 Hz below their individual gamma frequency (control condition), while they were performing a between-channel gap detection task. As expected, individual gamma frequencies correlated significantly with gap detection performance at baseline and in the experimental condition, transcranial alternating current stimulation modulated gap detection performance. In the control condition, stimulation did not modulate gap detection performance. In addition, in elderly, the effect of transcranial alternating current stimulation on auditory temporal resolution seems to be dependent on endogenous frequencies in auditory cortex: Elderlies with slower individual gamma frequencies and lower auditory temporal resolution profit from auditory transcranial alternating current stimulation and show increased gap detection performance during stimulation. Our results strongly suggest individualized transcranial alternating current stimulation protocols for successful modulation of performance.
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Affiliation(s)
- Alina Baltus
- Experimental Psychology Lab, Cluster of Excellence "Hearing4all", European Medical School, Carl von Ossietzky University, Oldenburg, Germany
| | - Johannes Vosskuhl
- Experimental Psychology Lab, Cluster of Excellence "Hearing4all", European Medical School, Carl von Ossietzky University, Oldenburg, Germany
| | - Cindy Boetzel
- Experimental Psychology Lab, Cluster of Excellence "Hearing4all", European Medical School, Carl von Ossietzky University, Oldenburg, Germany
| | - Christoph Siegfried Herrmann
- Experimental Psychology Lab, Cluster of Excellence "Hearing4all", European Medical School, Carl von Ossietzky University, Oldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky University, Oldenburg, Germany
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248
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Fuscà M, Ruhnau P, Neuling T, Weisz N. Local Network-Level Integration Mediates Effects of Transcranial Alternating Current Stimulation. Brain Connect 2018; 8:212-219. [DOI: 10.1089/brain.2017.0564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Marco Fuscà
- Center for Mind/Brain Sciences, University of Trento, Trento, Italy
| | - Philipp Ruhnau
- Center for Mind/Brain Sciences, University of Trento, Trento, Italy
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
| | - Toralf Neuling
- Center for Mind/Brain Sciences, University of Trento, Trento, Italy
- Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
| | - Nathan Weisz
- Center for Mind/Brain Sciences, University of Trento, Trento, Italy
- Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
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249
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Albouy P, Baillet S, Zatorre RJ. Driving working memory with frequency-tuned noninvasive brain stimulation. Ann N Y Acad Sci 2018; 1423:126-137. [PMID: 29707781 DOI: 10.1111/nyas.13664] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 02/05/2018] [Accepted: 02/13/2018] [Indexed: 12/21/2022]
Abstract
Frequency-tuned noninvasive brain stimulation is a recent approach in cognitive neuroscience that involves matching the frequency of transcranially applied electromagnetic fields to that of specific oscillatory components of the underlying neurophysiology. The objective of this method is to modulate ongoing/intrinsic brain oscillations, which correspond to rhythmic fluctuations of neural excitability, to causally change behavior. We review the impact of frequency-tuned noninvasive brain stimulation on the research field of human working memory. We argue that this is a powerful method to probe and understand the mechanisms of memory functions, targeting specifically task-related oscillatory dynamics, neuronal representations, and brain networks. We report the main behavioral and neurophysiological outcomes published to date, in particular, how functionally relevant oscillatory signatures in signal power and interregional connectivity yield causal changes of working memory abilities. We also present recent developments of the technique that aim to modulate cross-frequency coupling in polyrhythmic neural activity. Overall, the method has led to significant advances in our understanding of the mechanisms of systems neuroscience, and the role of brain oscillations in cognition and behavior. We also emphasize the translational impact of noninvasive brain stimulation techniques in the development of therapeutic approaches.
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Affiliation(s)
- Philippe Albouy
- Montreal Neurological Institute, McGill University, Montreal, Canada
- International Laboratory for Brain, Music and Sound Research (BRAMS), Montreal, Canada
| | - Sylvain Baillet
- Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Robert J Zatorre
- Montreal Neurological Institute, McGill University, Montreal, Canada
- International Laboratory for Brain, Music and Sound Research (BRAMS), Montreal, Canada
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250
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Abstract
PURPOSE OF REVIEW An increase in oscillatory activity in the γ-frequency band (approximately 50-100 Hz) has long been noted during human movement. However, its functional role has been difficult to elucidate. The advent of novel techniques, particularly transcranial alternating current stimulation (tACS), has dramatically increased our ability to study γ oscillations. Here, we review our current understanding of the role of γ oscillations in the human motor cortex, with reference to γ activity outside the motor system, and evidence from animal models. RECENT FINDINGS Evidence for the neurophysiological basis of human γ oscillations is beginning to emerge. Multimodal studies, essential given the necessarily indirect measurements acquired in humans, are beginning to provide convergent evidence for the role of γ oscillations in movement, and their relationship to plasticity. SUMMARY Human motor cortical γ oscillations appear to play a key role in movement, and relate to learning. However, there are still major questions to be answered about their physiological basis and precise role in human plasticity. It is to be hoped that future research will take advantage of recent technical advances and the physiological basis and functional significance of this intriguing and important brain rhythm will be fully elucidated.
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Affiliation(s)
- Magdalena Nowak
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX UK
| | - Catharina Zich
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX UK
| | - Charlotte J. Stagg
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX3 9DU UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX UK
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