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Sandrini M, Manenti R, Sahin H, Cotelli M. Effects of transcranial electrical stimulation on episodic memory in physiological and pathological ageing. Ageing Res Rev 2020; 61:101065. [PMID: 32275953 DOI: 10.1016/j.arr.2020.101065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/04/2020] [Accepted: 04/01/2020] [Indexed: 12/29/2022]
Abstract
Memory for personally-relevant past events (episodic memory) is critical for activities of daily living. Decline in this type of declarative long-term memory is a common characteristic of healthy ageing, a process accelerated in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Transcranial electrical stimulation (tES) has been used as a strategy to ameliorate episodic memory. Here, we critically review studies investigating whether tES may improve episodic memory in physiological and pathological ageing. Most of the studies suggest that tES over the prefrontal or temporoparietal cortices can have a positive effect on episodic memory, but the transfer to improvement of execution of daily living activities is still unknown. Further work is needed to better understand the mechanisms underlying the effects of stimulation, combine tES with neuroimaging and optimizing the dosing of stimulation. Future studies should also investigate the optimal timing of stimulation and the combination with medications to induce long-lasting beneficial effects in pathological ageing. More open science efforts should be done to improve rigor and reliability of tES in ageing research.
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Leach RC, McCurdy MP, Trumbo MC, Matzen LE, Leshikar ED. Differential Age Effects of Transcranial Direct Current Stimulation on Associative Memory. J Gerontol B Psychol Sci Soc Sci 2019; 74:1163-1173. [PMID: 29401230 PMCID: PMC6748776 DOI: 10.1093/geronb/gby003] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 01/10/2018] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVES Older adults experience associative memory deficits relative to younger adults (Old & Naveh-Benjamin, 2008). The aim of this study was to test the effect of transcranial direct current stimulation (tDCS) on face-name associative memory in older and younger adults. METHOD Experimenters applied active (1.5 mA) or sham (0.1 mA) stimulation with the anode placed over the left dorsolateral prefrontal cortex (dlPFC) during a face-name encoding task, and measured both cued recall and recognition performance. Participants completed memory tests immediately after stimulation and after a 24-h delay to examine both immediate and delayed stimulation effects on memory. RESULTS Results showed improved face-name associative memory performance for both recall and recognition measures, but only for younger adults, whereas there was no difference between active and sham stimulation for older adults. For younger adults, stimulation-induced memory improvements persisted after a 24-h delay, suggesting delayed effects of tDCS after a consolidation period. DISCUSSION Although effective in younger adults, these results suggest that older adults may be resistant to this intervention, at least under the stimulation parameters used in the current study. This finding is inconsistent with a commonly seen trend, where tDCS effects on cognition are larger in older than younger adults.
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Theta band high definition transcranial alternating current stimulation, but not transcranial direct current stimulation, improves associative memory performance. Sci Rep 2019; 9:8562. [PMID: 31189985 PMCID: PMC6561937 DOI: 10.1038/s41598-019-44680-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/22/2019] [Indexed: 11/08/2022] Open
Abstract
Associative memory (AM) deficits are common in neurodegenerative disease and novel therapies aimed at improving these faculties are needed. Theta band oscillations within AM networks have been shown to be important for successful memory encoding and modulating these rhythms represents a promising strategy for cognitive enhancement. Transcranial alternating current stimulation (TACS) has been hypothesized to entrain and increase power of endogenous brain rhythms. For this reason, we hypothesized that focal delivery of theta band electrical current, using high-definition TACS, would result in improved AM performance compared to sham stimulation or transcranial direct current stimulation (TDCS). In this pilot study, 60 healthy subjects were randomized to receive high definition TACS, high definition TDCS, or sham stimulation delivered to the right fusiform cortex during encoding of visual associations. Consistent with our hypothesis, improved AM performance was observed in the TACS group, while TDCS had no effect. However, TACS also resulted in improved correct rejection of never seen items, reduced false memory, and reduced forgetting, suggesting the effect may not be specific for AM processes. Overall, this work informs strategies for improving associative memory and suggests alternating current is more effective than direct current stimulation in some contexts.
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Galli G, Vadillo MA, Sirota M, Feurra M, Medvedeva A. A systematic review and meta-analysis of the effects of transcranial direct current stimulation (tDCS) on episodic memory. Brain Stimul 2018; 12:231-241. [PMID: 30503376 DOI: 10.1016/j.brs.2018.11.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 10/26/2018] [Accepted: 11/11/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND In the past decade, several studies have examined the effects of transcranial direct current stimulation (tDCS) on long-term episodic memory formation and retrieval. These studies yielded conflicting results, likely due to differences in stimulation parameters, experimental design and outcome measures. OBJECTIVES In this work we aimed to assess the robustness of tDCS effects on long-term episodic memory using a meta-analytical approach. METHODS We conducted four meta-analyses to analyse the effects of anodal and cathodal tDCS on memory accuracy and response times. We also used a moderator analysis to examine whether the size of tDCS effects varied as a function of specific stimulation parameters and experimental conditions. RESULTS Although all selected studies reported a significant effect of tDCS in at least one condition in the published paper, the results of the four meta-analyses showed only statistically non-significant close-to-zero effects. A moderator analysis suggested that for anodal tDCS, the duration of the stimulation and the task used to probe memory moderated the effectiveness of tDCS. For cathodal tDCS, site of stimulation was a significant moderator, although this result was based on only a few observations. CONCLUSIONS To warrant theoretical advancement and practical implications, more rigorous research is needed to fully understand whether tDCS reliably modulates episodic memory, and the specific circumstances under which this modulation does, and does not, occur.
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Affiliation(s)
- Giulia Galli
- Department of Psychology, Kingston University, Penrhyn Road, Kingston Upon Thames, KT1 2EE, United Kingdom.
| | - Miguel A Vadillo
- Departamento de Psicología Básica, Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain
| | - Miroslav Sirota
- Department of Psychology, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom
| | - Matteo Feurra
- School of Psychology, Centre for Cognition and Decision Making, National Research University Higher School of Economics, 101000, Moscow, Armyanskiy per. 4, c2, Russian Federation
| | - Angela Medvedeva
- Department of Psychology, Kingston University, Penrhyn Road, Kingston Upon Thames, KT1 2EE, United Kingdom
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Ventura de Oliveira JR, Romano-Silva MA, Ugrinowitsch H, Apolinário-Souza T, Fernandes LA, Parma JO, Lage GM. Cathodal tDCS of the Left Posterior Parietal Cortex Increases Proprioceptive Drift. J Mot Behav 2018; 51:272-280. [DOI: 10.1080/00222895.2018.1468311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- João Roberto Ventura de Oliveira
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Herbert Ugrinowitsch
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Tércio Apolinário-Souza
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lidiane Aparecida Fernandes
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Juliana Otoni Parma
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Guilherme Menezes Lage
- School of Physiotherapy, Occupational Physiotherapy and Physical Education, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Hampstead BM, Towler S, Stringer AY, Sathian K. Continuous measurement of object location memory is sensitive to effects of age and mild cognitive impairment and related to medial temporal lobe volume. ALZHEIMER'S & DEMENTIA: DIAGNOSIS, ASSESSMENT & DISEASE MONITORING 2017; 10:76-85. [PMID: 29255787 PMCID: PMC5724745 DOI: 10.1016/j.dadm.2017.10.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Introduction We present findings of a novel and ecologically relevant associative memory test, the Object Location Touchscreen Test (OLTT), which was posited as sensitive to early medial temporal lobe compromise associated with mild cognitive impairment (MCI). Methods A total of 114 participants, including healthy young and older controls and patients with MCI, completed the OLTT and standard neuropsychological testing. The OLTT required participants to recall the location of objects under free and cued recall conditions, with accuracy evaluated using distance measures (i.e., a continuous error score), and a standard recognition format. Correlations between performance and volumetric data were evaluated from a subset of 77 participants. Results Significant age effects were dwarfed by MCI effects across all test conditions. OLTT Cued Recall was strongly and specifically related to the volume of disease-relevant medial temporal lobe regions, generally more than traditional memory tests. Discussion The OLTT may be sensitive to early structural compromise in regions affected by Alzheimer's disease. Evaluated age and mild cognitive impairment effects using ecologically relevant object location (OL) task. Performance evaluated using both continuous and dichotomous measures of accuracy. Greater decline in OL memory with mild cognitive impairment than with “healthy” aging. Performance, especially continuous measure, reflected medial temporal integrity. Novel OL memory task may be sensitive to early structural compromise.
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Affiliation(s)
- Benjamin M Hampstead
- Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.,Department of Psychiatry, Neuropsychology Program, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, Michigan Alzheimer's Disease Core Center, University of Michigan, Ann Arbor, MI, USA.,Rehabilitation R&D Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, USA.,Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
| | - Stephen Towler
- Rehabilitation R&D Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, USA
| | - Anthony Y Stringer
- Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA.,Department of Psychology, Emory University, Atlanta, GA, USA
| | - Krishnankutty Sathian
- Rehabilitation R&D Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, USA.,Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA.,Department of Neurology, Emory University, Atlanta, GA, USA.,Department of Psychology, Emory University, Atlanta, GA, USA
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Hampstead BM, Sathian K, Bikson M, Stringer AY. Combined mnemonic strategy training and high-definition transcranial direct current stimulation for memory deficits in mild cognitive impairment. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2017; 3:459-470. [PMID: 29067352 PMCID: PMC5651427 DOI: 10.1016/j.trci.2017.04.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Memory deficits characterize Alzheimer's dementia and the clinical precursor stage known as mild cognitive impairment. Nonpharmacologic interventions hold promise for enhancing functioning in these patients, potentially delaying functional impairment that denotes transition to dementia. Previous findings revealed that mnemonic strategy training (MST) enhances long-term retention of trained stimuli and is accompanied by increased blood oxygen level-dependent signal in the lateral frontal and parietal cortices as well as in the hippocampus. The present study was designed to enhance MST generalization, and the range of patients who benefit, via concurrent delivery of transcranial direct current stimulation (tDCS). METHODS This protocol describes a prospective, randomized controlled, four-arm, double-blind study targeting memory deficits in those with mild cognitive impairment. Once randomized, participants complete five consecutive daily sessions in which they receive either active or sham high definition tDCS over the left lateral prefrontal cortex, a region known to be important for successful memory encoding and that has been engaged by MST. High definition tDCS (active or sham) will be combined with either MST or autobiographical memory recall (comparable to reminiscence therapy). Participants undergo memory testing using ecologically relevant measures and functional magnetic resonance imaging before and after these treatment sessions as well as at a 3-month follow-up. Primary outcome measures include face-name and object-location association tasks. Secondary outcome measures include self-report of memory abilities as well as a spatial navigation task (near transfer) and prose memory (medication instructions; far transfer). Changes in functional magnetic resonance imaging will be evaluated during both task performance and the resting-state using activation and connectivity analyses. DISCUSSION The results will provide important information about the efficacy of cognitive and neuromodulatory techniques as well as the synergistic interaction between these promising approaches. Exploratory results will examine patient characteristics that affect treatment efficacy, thereby identifying those most appropriate for intervention.
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Affiliation(s)
- Benjamin M. Hampstead
- Mental Health Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
- Neuropsychology Program, Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
- Michigan Alzheimer's Disease Core Center, University of Michigan, Ann Arbor, MI, USA
- Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
| | - Krishnankutty Sathian
- Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
- Department of Neurology, Emory University, Atlanta, GA, USA
- Center of Excellence for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, USA
- Department of Psychology, Emory University, Atlanta, GA, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
| | - Anthony Y. Stringer
- Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
- Department of Psychology, Emory University, Atlanta, GA, USA
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Zimmermann K, Eschen A. Brain regions involved in subprocesses of small-space episodic object-location memory: a systematic review of lesion and functional neuroimaging studies. Memory 2016; 25:487-519. [DOI: 10.1080/09658211.2016.1188965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Kathrin Zimmermann
- International Normal Aging and Plasticity Center (INAPIC), University of Zurich, Zurich, Switzerland
- Department of Gerontopsychology, University of Zurich, Zurich, Switzerland
- University Research Priority Program “Dynamics of Healthy Aging”, University of Zurich, Zurich, Switzerland
| | - Anne Eschen
- International Normal Aging and Plasticity Center (INAPIC), University of Zurich, Zurich, Switzerland
- University Research Priority Program “Dynamics of Healthy Aging”, University of Zurich, Zurich, Switzerland
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Krishnamurthy V, Gopinath K, Brown GS, Hampstead BM. Resting-state fMRI reveals enhanced functional connectivity in spatial navigation networks after transcranial direct current stimulation. Neurosci Lett 2015; 604:80-5. [PMID: 26240994 DOI: 10.1016/j.neulet.2015.07.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 11/28/2022]
Abstract
A number of studies have established that transcranial direct current stimulation (tDCS) modulates cortical excitability. We previously demonstrated polarity dependent changes in parietal lobe blood oxygen level dependent (BOLD) fMRI in a group of young adults during a spatial navigation task [15]. Here we used resting state functional connectivity (rsFC) to examine whether analogous changes were also evident during the resting state. Participants were randomized to either a parietal-anodal, frontal-cathodal (P+F-) or the opposite montage (P-F+) and received 20min of tDCS (2mA) before undergoing resting-state fMRI. rsFC was evaluated between the groups by placing a seed in the medial superior parietal lobule (mSPL), which was under the target electrode. rsFC between the mSPL and a number of other areas involved in spatial navigation, scene processing, and sensorimotor processing was significantly higher in the P+F- than the P-F+ group. Thus, the modulatory effects of tDCS were evident during rest and suggest that stimulation primes not just the underlying neocortex but an extended network that can be recruited as necessary during active task performance.
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Affiliation(s)
| | - Kaundinya Gopinath
- Department of Radiology & Imaging Sciences, Emory University, Atlanta, GA, USA.
| | - Gregory S Brown
- Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
| | - Benjamin M Hampstead
- Rehabilitation R&D Center of Excellence, Atlanta VAMC, Decatur, GA, USA; Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA
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