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van der Groen O, Rafique SA, Willmot N, Murphy MG, Tisnovsky E, Brunyé TT. Transcutaneous and transcranial electrical stimulation for enhancing military performance: an update and systematic review. Front Hum Neurosci 2025; 19:1501209. [PMID: 40098747 PMCID: PMC11911350 DOI: 10.3389/fnhum.2025.1501209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2024] [Accepted: 02/12/2025] [Indexed: 03/19/2025] Open
Abstract
Introduction Electrical stimulation (ES), including transcranial electrical stimulation (tES) and transcutaneous vagus nerve stimulation (tVNS), has shown potential for cognitive enhancement in military contexts. Various types of ES, such as transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), modulate neuronal membrane potentials and cortical excitability, potentially improving cognitive functions relevant to military training and operations. Methods This systematic review updates previous findings by examining studies published between 2019 and 2024 that investigated electrical stimulation effects on cognitive performance in military personnel and tasks. We focused on whether the studies addressed key questions about the generalizability of lab findings to military tasks, the frequency and intensity of adverse effects, the impact of repeated ES administration, and the ethical and regulatory considerations for its use in potentially vulnerable military populations. Results Eleven studies met the inclusion criteria; most demonstrated overall low to some concerns, however, two of these had overall high risk of bias. While tES and tVNS showed some promise for enhancing multitasking and visual search performance, the results were mixed, with no reliable effects on vigilance tasks. Discussion The reviewed studies highlight the need for a better understanding of ES mechanisms, optimal stimulation parameters, and individual differences in response to ES. They also highlight the importance of conducting high-powered research in military settings to evaluate the efficacy, safety, and ethical implications of ES. Future research should address the generalizability of lab-based results to real-world military tasks, monitor the frequency and intensity of adverse effects, and explore the long-term impacts of repeated administration. Furthermore, ethical and regulatory considerations are crucial for the responsible application of ES in military contexts, and a series of outstanding questions is posed to guide continuing research in this domain.
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Affiliation(s)
- Onno van der Groen
- Defence Science and Technology Group, Human and Decision Sciences, Department of Defence, Edinburgh, SA, Australia
| | - Sara A. Rafique
- Defence Science and Technology Laboratory, Salisbury, United Kingdom
| | - Nick Willmot
- Defence Science and Technology Group, Human and Decision Sciences, Department of Defence, Edinburgh, SA, Australia
| | - Margaret G. Murphy
- U.S. Army DEVCOM Soldier Center, Natick, MA, United States
- Center for Applied Brain and Cognitive Sciences, Tufts University, Medford, MA, United States
| | - Eulalia Tisnovsky
- Center for Applied Brain and Cognitive Sciences, Tufts University, Medford, MA, United States
| | - Tad T. Brunyé
- U.S. Army DEVCOM Soldier Center, Natick, MA, United States
- Center for Applied Brain and Cognitive Sciences, Tufts University, Medford, MA, United States
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Andalib S, Divani AA, Ayata C, Baig S, Arsava EM, Topcuoglu MA, Cáceres EL, Parikh V, Desai MJ, Majid A, Girolami S, Di Napoli M. Vagus Nerve Stimulation in Ischemic Stroke. Curr Neurol Neurosci Rep 2023; 23:947-962. [PMID: 38008851 PMCID: PMC10841711 DOI: 10.1007/s11910-023-01323-w] [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] [Accepted: 10/30/2023] [Indexed: 11/28/2023]
Abstract
PURPOSE OF REVIEW Vagus nerve stimulation (VNS) has emerged as a potential therapeutic approach for neurological and psychiatric disorders. In recent years, there has been increasing interest in VNS for treating ischemic stroke. This review discusses the evidence supporting VNS as a treatment option for ischemic stroke and elucidates its underlying mechanisms. RECENT FINDINGS Preclinical studies investigating VNS in stroke models have shown reduced infarct volumes and improved neurological deficits. Additionally, VNS has been found to reduce reperfusion injury. VNS may promote neuroprotection by reducing inflammation, enhancing cerebral blood flow, and modulating the release of neurotransmitters. Additionally, VNS may stimulate neuroplasticity, thereby facilitating post-stroke recovery. The Food and Drug Administration has approved invasive VNS (iVNS) combined with rehabilitation for ischemic stroke patients with moderate to severe upper limb deficits. However, iVNS is not feasible in acute stroke due to its time-sensitive nature. Non-invasive VNS (nVNS) may be an alternative approach for treating ischemic stroke. While the evidence from preclinical studies and clinical trials of nVNS is promising, the mechanisms through which VNS exerts its beneficial effects on ischemic stroke are still being elucidated. Therefore, further research is needed to better understand the efficacy and underlying mechanisms of nVNS in ischemic stroke. Moreover, large-scale randomized clinical trials are necessary to determine the optimal nVNS protocols, assess its long-term effects on stroke recovery and outcomes, and identify the potential benefits of combining nVNS with other rehabilitation strategies.
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Affiliation(s)
- Sasan Andalib
- Research Unit of Neurology, Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
- Department of Neurology, Odense University Hospital, Odense, Denmark
| | - Afshin A Divani
- Department of Neurology, School of Medicine, University of New Mexico, Albuquerque, NM, 87131, USA.
| | - Cenk Ayata
- Neurovascular Research Unit, Department of Radiology and Stroke Service, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Sheharyar Baig
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Ethem Murat Arsava
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | | | | | - Vinay Parikh
- Department of Psychology and Neuroscience, Temple University, Philadelphia, PA, USA
| | - Masoom J Desai
- Department of Neurology, School of Medicine, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Arshad Majid
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Sara Girolami
- Neurological Service, SS Annunziata Hospital, Sulmona, L'Aquila, Italy
| | - Mario Di Napoli
- Neurological Service, SS Annunziata Hospital, Sulmona, L'Aquila, Italy
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Naparstek S, Yeh AK, Mills-Finnerty C. Transcutaneous Vagus Nerve Stimulation (tVNS) applications in cognitive aging: a review and commentary. Front Aging Neurosci 2023; 15:1145207. [PMID: 37496757 PMCID: PMC10366452 DOI: 10.3389/fnagi.2023.1145207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 06/12/2023] [Indexed: 07/28/2023] Open
Abstract
Differentiating healthy from pathological aging trajectories is extremely timely, as the global population faces an inversion where older adults will soon outnumber younger 5:1. Many cognitive functions (e.g., memory, executive functions, and processing speed) decline with age, a process that can begin as early as midlife, and which predicts subsequent diagnosis with dementia. Although dementia is a devastating and costly diagnosis, there remains limited evidence for medications, therapies, and devices that improve cognition or attenuate the transition into dementia. There is an urgent need to intervene early in neurodegenerative processes leading to dementia (e.g., depression and mild cognitive impairment). In this targeted review and commentary, we highlight transcutaneous Vagus Nerve Stimulation (tVNS) as a neurostimulation method with unique opportunities for applications in diseases of aging, reviewing recent literature, feasibility of use with remote data collection methods/telehealth, as well as limitations and conflicts in the literature. In particular, small sample sizes, uneven age distributions of participants, lack of standardized protocols, and oversampling of non-representative groups (e.g., older adults with no comorbid diagnoses) limit our understanding of the potential of this method. We offer recommendations for how to improve representativeness, statistical power, and generalizability of tVNS research by integrating remote data collection techniques.
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Affiliation(s)
- Sharon Naparstek
- Department of Psychology, Bar-Ilan University, Ramat Gan, Israel
| | - Ashley K. Yeh
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Colleen Mills-Finnerty
- VA Palo Alto Health Care System, Palo Alto, CA, United States
- Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA, United States
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Konjusha A, Yu S, Mückschel M, Colzato L, Ziemssen T, Beste C. Auricular Transcutaneous Vagus Nerve Stimulation Specifically Enhances Working Memory Gate Closing Mechanism: A System Neurophysiological Study. J Neurosci 2023; 43:4709-4724. [PMID: 37221097 PMCID: PMC10286950 DOI: 10.1523/jneurosci.2004-22.2023] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 04/24/2023] [Accepted: 04/30/2023] [Indexed: 05/25/2023] Open
Abstract
Everyday tasks and goal-directed behavior involve the maintenance and continuous updating of information in working memory (WM). WM gating reflects switches between these two core states. Neurobiological considerations suggest that the catecholaminergic and the GABAergic are likely involved in these dynamics. Both of these neurotransmitter systems likely underlie the effects to auricular transcutaneous vagus nerve stimulation (atVNS). We examine the effects of atVNS on WM gating dynamics and their underlying neurophysiological and neurobiological processes in a randomized crossover study design in healthy humans of both sexes. We show that atVNS specifically modulates WM gate closing and thus specifically modulates neural mechanisms enabling the maintenance of information in WM. WM gate opening processes were not affected. atVNS modulates WM gate closing processes through the modulation of EEG alpha band activity. This was the case for clusters of activity in the EEG signal referring to stimulus information, motor response information, and fractions of information carrying stimulus-response mapping rules during WM gate closing. EEG-beamforming shows that modulations of activity in fronto-polar, orbital, and inferior parietal regions are associated with these effects. The data suggest that these effects are not because of modulations of the catecholaminergic (noradrenaline) system as indicated by lack of modulatory effects in pupil diameter dynamics, in the inter-relation of EEG and pupil diameter dynamics and saliva markers of noradrenaline activity. Considering other findings, it appears that a central effect of atVNS during cognitive processing refers to the stabilization of information in neural circuits, putatively mediated via the GABAergic system.SIGNIFICANCE STATEMENT Goal-directed behavior depends on how well information in short-term memory can be flexibly updated but also on how well it can be shielded from distraction. These two functions were guarded by a working memory gate. We show how an increasingly popular brain stimulation techniques specifically enhances the ability to close the working memory gate to shield information from distraction. We show what physiological and anatomic aspects underlie these effects.
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Affiliation(s)
- Anyla Konjusha
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden 01307, Germany
| | - Shijing Yu
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden 01307, Germany
| | - Moritz Mückschel
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden 01307, Germany
| | - Lorenza Colzato
- Faculty of Psychology, Shandong Normal University, Jinan 250014, China
| | - Tjalf Ziemssen
- Department of Neurology, Faculty of Medicine, MS Centre, TU Dresden, Dresden 01307, Germany
| | - Christian Beste
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Dresden 01307, Germany
- Faculty of Psychology, Shandong Normal University, Jinan 250014, China
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Wang C, Zeng L, Cao X, Dai J, Liu Y, Gao Z, Qin Y, Yang L, Wang H, Wen Z. Synergistic effects of transcutaneous vagus nerve stimulation and inhibitory control training on electrophysiological performance in healthy adults. Front Neurosci 2023; 17:1123860. [PMID: 36968500 PMCID: PMC10033592 DOI: 10.3389/fnins.2023.1123860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/23/2023] [Indexed: 03/11/2023] Open
Abstract
Transcutaneous vagal nerve stimulation (tVNS) is a non-invasive nerve stimulation technique that exerts a positive “exogenous” online neuromodulatory effect on inhibitory control (IC). Additionally, IC training (ICT) is an effective approach for enhancing IC via the “endogenous” activation of brain regions implicated in this process. The aim of the present study was to examine the synergistic effects of tVNS and ICT on IC enhancement. For this, we measured the changes in neural activity in frontal, fronto-central, and central regions in the time domain of the N2 component and the frequency domain of alpha power during the stop signal task. A total of 58 participants were randomly divided into four groups that received five sessions of either ICT or sham ICT with either online tVNS or sham tVNS. No differences in N2 amplitude were detected after any of the interventions. However, N2 latency shortened after tVNS + ICT in frontal, fronto-central, and central regions. N2 latency shortened after the intervention of sham tVNS + ICT in frontal region. Moreover, alpha power after tVNS + ICT intervention was larger than those of the other interventions in frontal, fronto-central, and central regions. The obtained electrophysiological data suggested that combining tVNS with ICT has synergistic ameliorative effects on IC, and provide evidence supporting the IC-enhancing potential of tVNS combined with ICT.
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Affiliation(s)
- Chunchen Wang
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Lingwei Zeng
- Department of Medical Psychology, Air Force Medical University, Xi’an, China
| | - Xinsheng Cao
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Jing Dai
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Yang Liu
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Zhijun Gao
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Yilong Qin
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| | - Lin Yang
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
- Lin Yang,
| | - Hang Wang
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
- Hang Wang,
| | - Zhihong Wen
- Department of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
- *Correspondence: Zhihong Wen,
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