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Chuderski A, Chinta SR. Transcranial alternating current stimulation barely enhances working memory in healthy adults: A meta-analysis. Brain Res 2024; 1839:149022. [PMID: 38801916 DOI: 10.1016/j.brainres.2024.149022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024]
Abstract
Working memory (WM) is a pivotal neural mechanism for cognitive function and ability. Transcranial alternating current stimulation (tACS) was used to improve WM by entraining key brain rhythms. We submitted to meta-analysis 143 effects of tACS on WM performance, found in 42 reports published between 2014 and 2023, encompassing a total of 1386 healthy adults stimulated. The overall effect size of 134 interventions intended to improve WM equaled Hedges' g = 0.076 [0.039, 0.113]. However, after correcting for a significant publication bias this effect size dropped to zero. By contrast, 9 interventions distorting the brain synchronization using antiphase tACS reliably decreased WM performance, with Hedges' g = -0.266, [-0.458, -0.074]. Individuating the targeted frequency band was the only reliable moderator. The disparity between our null outcome and moderately positive tACS effects estimated by previous meta-analyses resulted from our inclusion of the most recent studies mostly reporting negligible effects. Our results suggest that current tACS protocols barely enhance WM in healthy adults. More research is needed to develop effective methods for WM stimulation.
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2
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Biačková N, Adamová A, Klírová M. Transcranial alternating current stimulation in affecting cognitive impairment in psychiatric disorders: a review. Eur Arch Psychiatry Clin Neurosci 2024; 274:803-826. [PMID: 37682331 PMCID: PMC11127835 DOI: 10.1007/s00406-023-01687-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/21/2023] [Indexed: 09/09/2023]
Abstract
Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation method that, through its manipulation of endogenous oscillations, can affect cognition in healthy adults. Given the fact that both endogenous oscillations and cognition are impaired in various psychiatric diagnoses, tACS might represent a suitable intervention. We conducted a search of Pubmed and Web of Science databases and reviewed 27 studies where tACS is used in psychiatric diagnoses and cognition change is evaluated. TACS is a safe and well-tolerated intervention method, suitable for multiple-sessions protocols. It can be administered at home, individualized according to the patient''s anatomical and functional characteristics, or used as a marker of disease progression. The results are varying across diagnoses and applied protocols, with some protocols showing a long-term effect. However, the overall number of studies is small with a great variety of diagnoses and tACS parameters, such as electrode montage or used frequency. Precise mechanisms of tACS interaction with pathophysiological processes are only partially described and need further research. Currently, tACS seems to be a feasible method to alleviate cognitive impairment in psychiatric patients; however, a more robust confirmation of efficacy of potential protocols is needed to introduce it into clinical practise.
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Affiliation(s)
- Nina Biačková
- Neurostimulation Department, National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Andrea Adamová
- Neurostimulation Department, National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Monika Klírová
- Neurostimulation Department, National Institute of Mental Health, Klecany, Czech Republic.
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.
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3
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Latrèche C, Mancini V, Rochas V, Maeder J, Cantonas LM, Férat V, Schneider M, Michel CM, Eliez S. Using transcranial alternating current stimulation to enhance working memory skills in youths with 22q11.2 deletion syndrome: A randomized double-blind sham-controlled study. Psychiatry Res 2024; 335:115835. [PMID: 38460352 DOI: 10.1016/j.psychres.2024.115835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 02/29/2024] [Accepted: 03/02/2024] [Indexed: 03/11/2024]
Abstract
Abnormal cognitive development, particularly working memory (WM) deficits, is among the first apparent manifestations of psychosis. Yet, cognitive impairment only shows limited response to current pharmacological treatment. Alternative interventions to target cognition are highly needed in individuals at high risk for psychosis, like carriers of 22q11.2 deletion syndrome (22q11.2DS). Here we applied theta-tuned transcranial alternating current stimulation (tACS) between frontal and temporal regions during a visual WM task in 34 deletion carriers. We conducted a double-blind sham-controlled study over three consecutive days. The stimulation parameters were derived from individual structural MRI scan and HD-EEG data acquired at baseline (Day 1) to model current intensity and individual preferential theta peak. Participants were randomized to either sham or tACS (Days 2 and 3) and then completed a visual WM task and a control task. Our findings reveal that tACS was safe and well-tolerated among participants. We found a significantly increased accuracy in the visual WM but not the control task following tACS. Moreover, this enhancement in WM accuracy was greater after tACS than during tACS, indicating stronger offline effects than online effects. Our study therefore supports the application of repeated sessions of brain stimulation in 22q11.2DS.
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Affiliation(s)
- Caren Latrèche
- Developmental Imaging and Psychopathology Lab, Department of Psychiatry, University of Geneva School of Medicine, Switzerland.
| | - Valentina Mancini
- Developmental Imaging and Psychopathology Lab, Department of Psychiatry, University of Geneva School of Medicine, Switzerland
| | - Vincent Rochas
- Functional Brain Mapping Laboratory, Department of Basic Neurosciences, University of Geneva, Switzerland; Human Neuroscience Platform, Fondation Campus Biotech Geneva, Geneva, Switzerland
| | - Johanna Maeder
- Developmental Imaging and Psychopathology Lab, Department of Psychiatry, University of Geneva School of Medicine, Switzerland
| | - Lucia M Cantonas
- Autism Brain and Behavior Laboratory, Department of Psychiatry, University of Geneva School of Medicine, Geneva, Switzerland
| | - Victor Férat
- Functional Brain Mapping Laboratory, Department of Basic Neurosciences, University of Geneva, Switzerland
| | - Maude Schneider
- Clinical Psychology Unit for Developmental and Intellectual Disabilities, Faculty of Psychology and Educational Sciences, University of Geneva, Switzerland
| | - Christoph M Michel
- Functional Brain Mapping Laboratory, Department of Basic Neurosciences, University of Geneva, Switzerland
| | - Stephan Eliez
- Developmental Imaging and Psychopathology Lab, Department of Psychiatry, University of Geneva School of Medicine, Switzerland; Department of Genetic Medicine and Development, University of Geneva School of Medicine, Switzerland
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4
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Wischnewski M, Berger TA, Opitz A, Alekseichuk I. Causal functional maps of brain rhythms in working memory. Proc Natl Acad Sci U S A 2024; 121:e2318528121. [PMID: 38536752 PMCID: PMC10998564 DOI: 10.1073/pnas.2318528121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/27/2024] [Indexed: 04/08/2024] Open
Abstract
Human working memory is a key cognitive process that engages multiple functional anatomical nodes across the brain. Despite a plethora of correlative neuroimaging evidence regarding the working memory architecture, our understanding of critical hubs causally controlling overall performance is incomplete. Causal interpretation requires cognitive testing following safe, temporal, and controllable neuromodulation of specific functional anatomical nodes. Such experiments became available in healthy humans with the advance of transcranial alternating current stimulation (tACS). Here, we synthesize findings of 28 placebo-controlled studies (in total, 1,057 participants) that applied frequency-specific noninvasive stimulation of neural oscillations and examined working memory performance in neurotypical adults. We use a computational meta-modeling method to simulate each intervention in realistic virtual brains and test reported behavioral outcomes against the stimulation-induced electric fields in different brain nodes. Our results show that stimulating anterior frontal and medial temporal theta oscillations and occipitoparietal gamma rhythms leads to significant dose-dependent improvement in working memory task performance. Conversely, prefrontal gamma modulation is detrimental to performance. Moreover, we found distinct spatial expression of theta subbands, where working memory changes followed orbitofrontal high-theta modulation and medial temporal low-theta modulation. Finally, all these results are driven by changes in working memory accuracy rather than processing time measures. These findings provide a fresh view of the working memory mechanisms, complementary to neuroimaging research, and propose hypothesis-driven targets for the clinical treatment of working memory deficits.
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Affiliation(s)
- Miles Wischnewski
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN55455
- Department of Experimental Psychology, University of Groningen, Groningen9712TS, The Netherlands
| | - Taylor A. Berger
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN55455
| | - Alexander Opitz
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN55455
| | - Ivan Alekseichuk
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN55455
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5
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Manippa V, Palmisano A, Nitsche MA, Filardi M, Vilella D, Logroscino G, Rivolta D. Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review. Neuropsychol Rev 2024; 34:338-361. [PMID: 36877327 PMCID: PMC10920470 DOI: 10.1007/s11065-023-09589-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 01/23/2023] [Indexed: 03/07/2023]
Abstract
Despite the numerous pharmacological interventions targeting dementia, no disease-modifying therapy is available, and the prognosis remains unfavorable. A promising perspective involves tackling high-frequency gamma-band (> 30 Hz) oscillations involved in hippocampal-mediated memory processes, which are impaired from the early stages of typical Alzheimer's Disease (AD). Particularly, the positive effects of gamma-band entrainment on mouse models of AD have prompted researchers to translate such findings into humans using transcranial alternating current stimulation (tACS), a methodology that allows the entrainment of endogenous cortical oscillations in a frequency-specific manner. This systematic review examines the state-of-the-art on the use of gamma-tACS in Mild Cognitive Impairment (MCI) and dementia patients to shed light on its feasibility, therapeutic impact, and clinical effectiveness. A systematic search from two databases yielded 499 records resulting in 10 included studies and a total of 273 patients. The results were arranged in single-session and multi-session protocols. Most of the studies demonstrated cognitive improvement following gamma-tACS, and some studies showed promising effects of gamma-tACS on neuropathological markers, suggesting the feasibility of gamma-tACS in these patients anyhow far from the strong evidence available for mouse models. Nonetheless, the small number of studies and their wide variability in terms of aims, parameters, and measures, make it difficult to draw firm conclusions. We discuss results and methodological limitations of the studies, proposing possible solutions and future avenues to improve research on the effects of gamma-tACS on dementia.
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Affiliation(s)
- Valerio Manippa
- Department of Education, Psychology and Communication, University of Bari "Aldo Moro", Bari, Italy.
| | - Annalisa Palmisano
- Department of Education, Psychology and Communication, University of Bari "Aldo Moro", Bari, Italy
| | - Michael A Nitsche
- Department of Psychology and Neurosciences, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
- Department of Neurology, University Medical Hospital Bergmannsheil, Bochum, Germany
| | - Marco Filardi
- Center for Neurodegenerative Diseases and the Aging Brain, University of Bari "Aldo Moro" at Pia Fondazione "Cardinale G. Panico", Tricase, Lecce, Italy
- Department of Basic Medicine, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Davide Vilella
- Center for Neurodegenerative Diseases and the Aging Brain, University of Bari "Aldo Moro" at Pia Fondazione "Cardinale G. Panico", Tricase, Lecce, Italy
| | - Giancarlo Logroscino
- Center for Neurodegenerative Diseases and the Aging Brain, University of Bari "Aldo Moro" at Pia Fondazione "Cardinale G. Panico", Tricase, Lecce, Italy
- Department of Basic Medicine, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Davide Rivolta
- Department of Education, Psychology and Communication, University of Bari "Aldo Moro", Bari, Italy
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6
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Maggio MG, Billeri L, Cardile D, Quartarone A, Calabrò RS. The Role of Innovation Technology in the Rehabilitation of Patients Affected by Huntington's Disease: A Scoping Review. Biomedicines 2023; 12:39. [PMID: 38255146 PMCID: PMC10813604 DOI: 10.3390/biomedicines12010039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/12/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
Huntington's disease is an autosomal dominant neurodegenerative disease caused by the repetition of cytosine, adenine, and guanine trinucleotides on the short arm of chromosome 4p16.3 within the Huntingtin gene. In this study, we aim to examine and map the existing evidence on the use of innovations in the rehabilitation of Huntington's disease. A scoping review was conducted on innovative rehabilitative treatments performed on patients with Huntington's disease. A search was performed on PubMed, Embase, Web of Science, and Cochrane databases to screen references of included studies and review articles for additional citations. Of an initial 1117 articles, only 20 met the search criteria. These findings showed that available evidence is still limited and that studies generally had small sample sizes and a high risk of bias. Regarding cognitive rehabilitation, it has emerged that VR- and PC-based methods as well as NIBS techniques are feasible and may have promising effects in individuals with Huntington's disease. On the other hand, scarce evidence was found for cognitive and motor training that might have a slight impact on overall cognitive function in individuals with Huntington's disease. Data show that further investigation is needed to explore the effects of innovative rehabilitation tools on cognition, especially considering that cognitive and psychiatric symptoms can precede the onset of motor symptoms by many years.
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Affiliation(s)
| | | | - Davide Cardile
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C. da Casazza, 98124 Messina, Italy; (M.G.M.); (L.B.)
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7
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Rozengurt R, Kuznietsov I, Kachynska T, Kozachuk N, Abramchuk O, Zhuravlov O, Mendelsohn A, Levy DA. Theta EEG neurofeedback promotes early consolidation of real life-like episodic memory. COGNITIVE, AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2023; 23:1473-1481. [PMID: 37752389 DOI: 10.3758/s13415-023-01125-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/23/2023] [Indexed: 09/28/2023]
Abstract
Theta oscillations are believed to coordinate neuronal activity related to human cognition, especially for memory functions. Theta power during learning and retrieval has been found to correlate with memory performance success. Additionally, up-regulating theta oscillations during a post-encoding epoch crucial for memory consolidation was previously shown to benefit long-term memory for acquired motor sequences, pictures, and object-location associations. However, it remains to be determined whether such effects would be found for more ecological aspects of long-term episodic memory. Therefore, the current study assessed neurofeedback-based theta upregulation effects on movie memory. After viewing a 15-minute silent, narrative movie, participants engaged in neurofeedback-based theta/beta up-regulation, neurofeedback beta/theta up-regulation as an active control condition, or an unrelated passive control task. Memory was tested three times: once immediately after watching the movie (as baseline); 24 hours thereafter; and once again 1 week later. Memory performance 1 week after encoding was significantly enhanced in the theta/beta up-regulation group compared with the other groups. Additionally, changes in neurofeedback theta/beta ratio from baseline EEG recordings correlated with long-term memory gains in retrieving the movie's content. These findings highlight the relationship between post-learning theta oscillations and the consolidation of episodic memory for a naturalistic event.
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Affiliation(s)
- Roman Rozengurt
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel
| | | | | | | | - Olha Abramchuk
- Lesya Ukrainka Volyn National University, Lutsk, Ukraine
| | | | - Avi Mendelsohn
- Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.
- Institute of Information Processing and Decision Making (IIPDM), University of Haifa, Haifa, Israel.
| | - Daniel A Levy
- Reichman University, Herzliya, Israel
- Palo Alto University, Palo Alto, CA, USA
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8
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Lee TL, Ding Z, Chan AS. Prefrontal hemodynamic features of older adults with preserved visuospatial working memory function. GeroScience 2023; 45:3513-3527. [PMID: 37501047 PMCID: PMC10643746 DOI: 10.1007/s11357-023-00862-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 06/26/2023] [Indexed: 07/29/2023] Open
Abstract
Memory decline has been observed in the aging population and is a risk factor for the later development of dementia. Understanding how memory is preserved in older adults has been an important topic. The present study examines the hemodynamic features of older adults whose memory is comparable with that of young adults. In the present study, 45 younger and 45 older adults performed the visual memory task with various difficulty levels (i.e., the items to be remembered), and their cerebral hemodynamics at each level were measured by functional near-infrared spectroscopy (fNIRS). The results showed that older adults exhibited higher activation than younger adults under more difficult but not easier levels. In addition, older adults whose performance is comparable with that of young adults (i.e., being able to remember six items) showed more right-lateralized activation. However, those unable to do so showed more left-lateralized activation. The results suggested that high-performing older adults possess successful compensatory mechanisms by recruiting cognitive resources in a specialized brain region.
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Affiliation(s)
- Tsz-Lok Lee
- Department of Psychology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Zihan Ding
- Department of Psychology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Agnes S Chan
- Department of Psychology, The Chinese University of Hong Kong, Shatin, Hong Kong.
- Research Centre for Neuropsychological Well-Being, The Chinese University of Hong Kong, Shatin, Hong Kong.
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9
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Violante IR, Alania K, Cassarà AM, Neufeld E, Acerbo E, Carron R, Williamson A, Kurtin DL, Rhodes E, Hampshire A, Kuster N, Boyden ES, Pascual-Leone A, Grossman N. Non-invasive temporal interference electrical stimulation of the human hippocampus. Nat Neurosci 2023; 26:1994-2004. [PMID: 37857775 PMCID: PMC10620081 DOI: 10.1038/s41593-023-01456-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 09/06/2023] [Indexed: 10/21/2023]
Abstract
Deep brain stimulation (DBS) via implanted electrodes is used worldwide to treat patients with severe neurological and psychiatric disorders. However, its invasiveness precludes widespread clinical use and deployment in research. Temporal interference (TI) is a strategy for non-invasive steerable DBS using multiple kHz-range electric fields with a difference frequency within the range of neural activity. Here we report the validation of the non-invasive DBS concept in humans. We used electric field modeling and measurements in a human cadaver to verify that the locus of the transcranial TI stimulation can be steerably focused in the hippocampus with minimal exposure to the overlying cortex. We then used functional magnetic resonance imaging and behavioral experiments to show that TI stimulation can focally modulate hippocampal activity and enhance the accuracy of episodic memories in healthy humans. Our results demonstrate targeted, non-invasive electrical stimulation of deep structures in the human brain.
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Affiliation(s)
- Ines R Violante
- School of Psychology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.
| | - Ketevan Alania
- Department of Brain Sciences, Imperial College London, London, UK
- UK Dementia Research Institute, Imperial College London, London, UK
| | - Antonino M Cassarà
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
| | - Emma Acerbo
- Institut de Neurosciences des Systèmes, Aix-Marseille University, INSERM, Marseille, France
- Department of Neurology and Neurosurgery, Emory University Hospital, Atlanta, GA, USA
| | - Romain Carron
- Institut de Neurosciences des Systèmes, Aix-Marseille University, INSERM, Marseille, France
- Department of Functional and Stereotactic Neurosurgery, Timone University Hospital, Marseille, France
| | - Adam Williamson
- Institut de Neurosciences des Systèmes, Aix-Marseille University, INSERM, Marseille, France
- International Clinical Research Center, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Danielle L Kurtin
- School of Psychology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Edward Rhodes
- Department of Brain Sciences, Imperial College London, London, UK
- UK Dementia Research Institute, Imperial College London, London, UK
| | - Adam Hampshire
- Department of Brain Sciences, Imperial College London, London, UK
| | - Niels Kuster
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
- Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Edward S Boyden
- Departments of Brain and Cognitive Sciences, Media Arts and Sciences, and Biological Engineering, McGovern and Koch Institutes, Massachusetts Institute of Technology, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Alvaro Pascual-Leone
- Hinda and Arthur Marcus Institute for Aging Research and Deanna and Sidney Wolk Center for Memory Health, Hebrew SeniorLife, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Nir Grossman
- Department of Brain Sciences, Imperial College London, London, UK.
- UK Dementia Research Institute, Imperial College London, London, UK.
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Arulchelvan E, Vanneste S. Promising neurostimulation routes for targeting the hippocampus to improve episodic memory: A review. Brain Res 2023:148457. [PMID: 37315722 DOI: 10.1016/j.brainres.2023.148457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/24/2023] [Accepted: 06/06/2023] [Indexed: 06/16/2023]
Abstract
This review aims to highlight modern neurostimulation approaches that are effectively activating the hippocampus and enhancing episodic memory performance. The hippocampus is a brain region known to play an essential role in episodic memory processes. However, as it is nestled deep within the brain, it has been a challenging target for traditional neurostimulation approaches, with studies reporting inconsistent memory effects. Recent studies suggest more than half of the electrical current from non-invasive transcranial electrical stimulation (tES) methods may be attenuated by the human scalp, skull, and cerebral spinal fluid. Thus, this review aims to highlight novel neurostimulation approaches that are showing promise as alternative routes for activating hippocampal circuitry. Early evidence suggests temporal interference, closed-loop and individualized protocols, sensory stimulation and peripheral nerve-targeted tES protocols warrant further investigation. These approaches each provide promising routes for activating the hippocampus by a) increasing its functional connectiveness to key brain regions, b) strengthening synaptic plasticity mechanisms, or c) enhancing neural entrainment specifically within and between theta and gamma frequencies in these regions. Importantly, these three functional mechanisms and the hippocampus' structural integrity are negatively impacted throughout the progression of Alzheimer's Disease, with episodic memory deficits likewise evident in early stages. Consequently, depending on further validation of the approaches reviewed here, these techniques could offer significant applied therapeutic value for patients suffering from memory deficits or neurodegenerative diseases including amnestic Mild Cognitive Impairment or Alzheimer's disease.
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Affiliation(s)
- Elva Arulchelvan
- Lab for Clinical and Integrative Neuroscience, Trinity Institute for Neuroscience, School of Psychology, Trinity College Dublin, Ireland
| | - Sven Vanneste
- Global Brain Health Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
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11
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Sawai S, Murata S, Fujikawa S, Yamamoto R, Nakano H. Effects of θ High Definition-Transcranial Alternating Current Stimulation in the Anterior Cingulate Cortex on the Dominance of Attention Focus in Standing Postural Control. Behav Sci (Basel) 2023; 13:477. [PMID: 37366728 DOI: 10.3390/bs13060477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/28/2023] Open
Abstract
Attention focus affects performance in postural control while standing, and it is divided into internal focus (IF) and external focus (EF). Each individual has a predominant attention focus, and research has revealed that the dominance of attention focus may be an acquired trait. However, the impact of non-invasive brain stimulation on attention-focus dominance remains unexplored in the current literature. Here, we examined the effect of high-definition transcranial alternating current stimulation (HD-tACS) on θ waves in the anterior cingulate cortex (ACC) on standing postural control tasks in an EF condition for IF- and EF-dominant groups. The effect of θ HD-tACS on the ACC differed between IF- and EF-dominant groups, and θ HD-tACS in the IF-dominant group decreased the performance of standing postural control under the EF condition. The forced activation of the ACC with θ HD-tACS may have conversely reduced the activity of brain regions normally activated by the IF-dominant group. Additionally, the activation of ACC prioritized visual information processing and suppressed the superficial sensory processing that is normally potentially prioritized by the IF-dominant group. These results highlight the importance of changing the type of rehabilitation and sports training tasks to account for the individual's dominance of attention focus.
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Affiliation(s)
- Shun Sawai
- Graduate School of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
- Department of Rehabilitation, Kyoto Kuno Hospital, Kyoto 607-0981, Japan
| | - Shin Murata
- Graduate School of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
- Department of Physical Therapy, Faculty of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
| | - Shoya Fujikawa
- Graduate School of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
- Department of Rehabilitation, Kyoto Kuno Hospital, Kyoto 607-0981, Japan
| | - Ryosuke Yamamoto
- Graduate School of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
- Department of Rehabilitation, Tesseikai Neurosurgical Hospital, Osaka 575-8511, Japan
| | - Hideki Nakano
- Graduate School of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
- Department of Physical Therapy, Faculty of Health Sciences, Kyoto Tachibana University, Kyoto 607-8175, Japan
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12
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Senkowski D, Sobirey R, Haslacher D, Soekadar SR. Boosting working memory: Uncovering the differential effects of tDCS and tACS. Cereb Cortex Commun 2022; 3:tgac018. [PMID: 35592391 PMCID: PMC9113288 DOI: 10.1093/texcom/tgac018] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/07/2022] [Accepted: 04/14/2022] [Indexed: 11/12/2022] Open
Abstract
Abstract
Working memory (WM) is essential for reasoning, decision making and problem solving. Recently, there has been an increasing effort in improving WM through non-invasive brain stimulation, especially transcranial direct and alternating current stimulation (tDCS/tACS). Studies suggest that tDCS and tACS can modulate WM performance, but large variability in research approaches hinders identification of optimal stimulation protocols and interpretation of study results. Moreover, it is unclear whether tDCS and tACS differentially affect WM. Here, we summarize and compare studies examining the effects of tDCS and tACS on WM performance in healthy adults. Following PRISMA-selection criteria, our systematic review resulted in 43 studies (29 tDCS, 11 tACS, 3 both) with a total of 1826 adult participants. For tDCS, only 4 out of 23 single-session studies reported effects on WM, while 7 out of 9 multi-session experiments showed positive effects on WM training. For tACS, 10 out of 14 studies demonstrated effects on WM, which were frequency dependent and robust for frontoparietal stimulation. Our review revealed no reliable effect of single-session tDCS on WM, but moderate effects of multi-session tDCS and single-session tACS. We discuss implications of these findings and future directions in the emerging research field of non-invasive brain stimulation and WM.
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Affiliation(s)
- Daniel Senkowski
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Psychiatry and Neurosciences, Charité Campus Mitte (CCM), Charitéplatz 1, 10117 Berlin
| | - Rabea Sobirey
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Psychiatry and Neurosciences, Charité Campus Mitte (CCM), Charitéplatz 1, 10117 Berlin
| | - David Haslacher
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Psychiatry and Neurosciences, Charité Campus Mitte (CCM), Charitéplatz 1, 10117 Berlin
| | - Surjo R Soekadar
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Psychiatry and Neurosciences, Charité Campus Mitte (CCM), Charitéplatz 1, 10117 Berlin
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Personalized Frequency Modulated Transcranial Electrical Stimulation for Associative Memory Enhancement. Brain Sci 2022; 12:brainsci12040472. [PMID: 35448003 PMCID: PMC9025454 DOI: 10.3390/brainsci12040472] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 12/25/2022] Open
Abstract
Associative memory (AM) is the ability to remember the relationship between previously unrelated items. AM is significantly affected by normal aging and neurodegenerative conditions, thus there is a growing interest in applying non-invasive brain stimulation (NIBS) techniques for AM enhancement. A growing body of studies identifies posterior parietal cortex (PPC) as the most promising cortical target for both transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) to modulate a cortico-hippocampal network that underlines AM. In that sense, theta frequency oscillatory tES protocols, targeted towards the hallmark oscillatory activity within the cortico-hippocampal network, are increasingly coming to prominence. To increase precision and effectiveness, the need for EEG guided individualization of the tES protocols is proposed. Here, we present the study protocol in which two types of personalized oscillatory tES–transcranial alternating current stimulation (tACS) and oscillatory transcranial direct current stimulation (otDCS), both frequency-modulated to the individual theta-band frequency (ITF), are compared to the non-oscillatory transcranial direct current stimulation (tDCS) and to the sham stimulation. The study has cross-over design with four tES conditions (tACS, otDCS, tDCS, sham), and the comprehensive set of neurophysiological (resting state EEG and AM-evoked EEG) and behavioral outcomes, including AM tasks (short-term associative memory, face–word, face–object, object-location), as well as measures of other cognitive functions (cognitive control, verbal fluency, and working memory).
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