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Legros A, Nissi J, Laakso I, Duprez J, Kavet R, Modolo J. Thresholds and Mechanisms of Human Magnetophosphene Perception Induced by Low Frequency Sinusoidal Magnetic Fields. Brain Stimul 2024:S1935-861X(24)00086-X. [PMID: 38740182 DOI: 10.1016/j.brs.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/07/2024] [Accepted: 05/07/2024] [Indexed: 05/16/2024] Open
Abstract
BACKGROUND Virtually everyone is exposed to power-frequency MF (50/60 Hz), inducing in our body electric fields and currents, potentially modulating brain function. MF-induced electric fields within the central nervous system can generate flickering visual perceptions (magnetophosphenes), which form the basis of international MF exposure guidelines and recommendations protecting workers and the general public. However, magnetophosphene perception thresholds were estimated 40 years ago in a small, unreplicated study with significant uncertainties and leaving open the question of the involved interaction site. METHODS We used a stimulation modality termed transcranial alternating magnetic stimulation (tAMS), delivering in situ sinusoidal electric fields comparable to transcranial alternating current stimulation (tACS). Magnetophosphene perception was quantified in 81 volunteers exposed to MF (eye or occipital exposure) between 0 and 50 mT at frequencies of 20, 50, 60 and 100 Hz. RESULTS Reliable magnetophosphene perception was induced with tAMS without any scalp sensation, a major advantage as compared to tACS. Frequency-dependent thresholds were quantified using binary logistic regressions hence allowing to establish condition dependent probabilities of perception. Results support an interaction between induced current density and retinal rod cells. CONCLUSION Beyond fundamental and immediate implications for international safety guidelines, and for identifying the interaction site underlying phosphene perception (ubiquitous in tACS experiments), our results support exploring the potential of tAMS for the differential diagnosis of retinal disorders and neuromodulation therapy.
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Affiliation(s)
- Alexandre Legros
- Human Threshold Research Group, Lawson Health Research Institute, London, ON, Canada; Departments of Medical Biophysics and Medical Imaging Western University, London, ON, Canada; School of Kinesiology, Western University, London, ON, Canada; EuroStim and EuroMov Digital Health in Motion, University of Montpellier and IMT Ales, Montpellier, France.
| | - Janita Nissi
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Ilkka Laakso
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Joan Duprez
- Univ Rennes, INSERM, LTSI - U1099, F-35000, France
| | | | - Julien Modolo
- Human Threshold Research Group, Lawson Health Research Institute, London, ON, Canada; Univ Rennes, INSERM, LTSI - U1099, F-35000, France
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Bouisset N, Nissi J, Laakso I, Reynolds RF, Legros A. Is activation of the vestibular system by electromagnetic induction a possibility in an MRI context? Bioelectromagnetics 2024; 45:171-183. [PMID: 38348647 DOI: 10.1002/bem.22497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 11/21/2023] [Accepted: 12/16/2023] [Indexed: 04/17/2024]
Abstract
In recent years, an increasing number of studies have discussed the mechanisms of vestibular activation in strong magnetic field settings such as occur in a magnetic resonance imaging scanner environment. Amid the different hypotheses, the Lorentz force explanation currently stands out as the most plausible mechanism, as evidenced by activation of the vestibulo-ocular reflex. Other hypotheses have largely been discarded. Nonetheless, both human data and computational modeling suggest that electromagnetic induction could be a valid mechanism which may coexist alongside the Lorentz force. To further investigate the induction hypothesis, we provide, herein, a first of its kind dosimetric analysis to estimate the induced electric fields at the vestibular system and compare them with what galvanic vestibular stimulation would generate. We found that electric fields strengths from induction match galvanic vestibular stimulation strengths generating vestibular responses. This review examines the evidence in support of electromagnetic induction of vestibular responses, and whether movement-induced time-varying magnetic fields should be further considered and investigated.
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Affiliation(s)
- Nicolas Bouisset
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
| | - Janita Nissi
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Ilkka Laakso
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Raymond F Reynolds
- School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Alexandre Legros
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
- EuroMov Digital Health in Motion, Univ Montpellier, IMT Mines Ales, Montpellier, France
- Departments of Medical Biophysics and Medical Imaging Western University, London, Ontario, Canada
- Eurostim, Montpellier, France
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Legros A, Corbacio M, Villard S, Souques M, Lambrozo J. A Pilot Study Evaluating the Feasibility of Testing for an Acute Impact of Human Exposure to a Power-line Frequency Magnetic Field on Blood Cortisol and Thyroid-Stimulating Hormone. Bioelectromagnetics 2022; 43:399-403. [PMID: 36403265 PMCID: PMC9828214 DOI: 10.1002/bem.22426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 09/10/2022] [Indexed: 11/21/2022]
Abstract
Numerous studies have been carried out on the potential effects of an extremely low frequency (ELF-0-300 Hz) magnetic field (MF) on human health. However, there is limited data on the effect of a high exposure level to ELF MFs for a prolonged period. Therefore, the objective of this pilot work was to demonstrate the feasibility of a study evaluating the stress hormone concentrations resulting from a 10-min exposure to a 60 Hz MF of several tens of thousands of µT. In this pilot study, human volunteers were thus exposed for the first time to a 60 Hz, 50 mT MF for a duration of 10 min. Stress hormone levels were measured before (once), during (twice) and after (once) this 10-min exposure period. The small sample size (n = 5) did not allow to conduct standard inferential statistical tests and no conclusion regarding the exposure effects can be drawn. However, this study demonstrates the feasibility of using a simple blood testing material in a protocol testing for the effect of a 10-min exposure to a high MF level in healthy human volunteers. © 2022 Bioelectromagnetics Society.
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Affiliation(s)
- Alexandre Legros
- Bioelectromagnetics and Human Threshold Research Group, Imaging DepartmentLawson Health Research InstituteOntarioLondonCanada,Departments of Medical Biophysics, Medical Imaging and School of KinesiologyWestern UniversityOntarioLondonCanada,EuroMov Digital Health in Motion, Université de MontpellierIMT Mines AlesMontpellierFrance,Division Neuromodulation R&DEuroStimMontpellierFrance
| | - Michael Corbacio
- Bioelectromagnetics and Human Threshold Research Group, Imaging DepartmentLawson Health Research InstituteOntarioLondonCanada
| | - Sébastien Villard
- Bioelectromagnetics and Human Threshold Research Group, Imaging DepartmentLawson Health Research InstituteOntarioLondonCanada,Departments of Medical Biophysics, Medical Imaging and School of KinesiologyWestern UniversityOntarioLondonCanada
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Bouisset N, Villard S, Legros A. Vestibular Extremely Low-Frequency Magnetic and Electric Stimulation Effects on Human Subjective Visual Vertical Perception. Bioelectromagnetics 2022; 43:355-367. [PMID: 35801487 PMCID: PMC9541167 DOI: 10.1002/bem.22417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/25/2022] [Accepted: 06/18/2022] [Indexed: 11/08/2022]
Abstract
Electric fields from both extremely low‐frequency magnetic fields (ELF‐MF) and alternating current (AC) stimulations impact human neurophysiology. As the retinal photoreceptors, vestibular hair cells are graded potential cells and are sensitive to electric fields. Electrophosphene and magnetophosphene literature suggests different impacts of AC and ELF‐MF on the vestibular hair cells. Furthermore, while AC modulates the vestibular system more globally, lateral ELF‐MF stimulations could be more utricular specific. Therefore, to further address the impact of ELF‐MF‐induced electric fields on the human vestibular system and the potential differences with AC stimulations, we investigated the effects of both stimulation modalities on the perception of verticality using a subjective visual vertical (SVV) paradigm. For similar levels of SVV precision, the ELF‐MF condition required more time to adjust SVV, and SVV variability was higher with ELF‐MF than with AC vestibular‐specific stimulations. Yet, the differences between AC and ELF‐MF stimulations were small. Overall, this study highlights small differences between AC and ELF‐MF vestibular stimulations, underlines a potential utricular contribution, and has implications for international exposure guidelines and standards. © 2022 Bioelectromagnetics Society.
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Affiliation(s)
- Nicolas Bouisset
- Human Threshold Research and Bioelectromagnetics Group, Imaging, Lawson Health Research Institute, London, Canada.,Department of Kinesiology, Western University, London, Canada
| | - Sébastien Villard
- Human Threshold Research and Bioelectromagnetics Group, Imaging, Lawson Health Research Institute, London, Canada.,Department of Kinesiology, Western University, London, Canada
| | - Alexandre Legros
- Human Threshold Research and Bioelectromagnetics Group, Imaging, Lawson Health Research Institute, London, Canada.,Department of Kinesiology, Western University, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada.,Euromov Digital Heath in Motion, Univ Montpellier, IMT Mines Ales, Montpellier, France.,EuroStim, Montpellier, France
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Abstract
OBJECTIVE We aimed at characterizing, in non-invasive human brain recordings, the large-scale, coordinated activation of distant brain regions thought to occur during conscious perception. This process is termed ignition in the Global Workspace Theory, and integration in Integrated Information Theory, which are two of the major theories of consciousness. APPROACH Here, we provide evidence for this process in humans by combining a magnetically-induced phosphene perception task with electroencephalography. Functional cortical networks were identified and characterized using graph theory to quantify the impact of conscious perception on local (segregation) and distant (integration) processing. MAIN RESULTS Conscious phosphene perception activated frequency-specific networks, each associated with a specific spatial scale of information processing. Integration increased within an alpha-band functional network, while changes in segregation occurred in the beta band. SIGNIFICANCE These results bring novel evidence for the functional role of distinct brain oscillations and confirm the key role of integration processes for conscious perception in humans.
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Affiliation(s)
- Julien Modolo
- Univ. Rennes, INSERM, LTSI - U1099, F-35000, Rennes, France. Human Threshold Research Group, Lawson Health Research Institute, London, ON, Canada. Co-first authors (equally contributed). Author to whom any correspondence should be addressed
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Evans ID, Palmisano S, Loughran SP, Legros A, Croft RJ. Frequency‐dependent and montage‐based differences in phosphene perception thresholds via transcranial alternating current stimulation. Bioelectromagnetics 2019; 40:365-374. [DOI: 10.1002/bem.22209] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 07/06/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Ian D. Evans
- School of PsychologyUniversity of Wollongong Wollongong Australia
- Illawarra Health and Medical Research InstituteUniversity of Wollongong Wollongong Australia
- Australian Centre for Electromagnetic Bioeffects Research Wollongong Australia
- Centre for Population Health Research on Electromagnetic EnergyMonash University Melbourne Australia
| | - Stephen Palmisano
- School of PsychologyUniversity of Wollongong Wollongong Australia
- Illawarra Health and Medical Research InstituteUniversity of Wollongong Wollongong Australia
| | - Sarah P. Loughran
- School of PsychologyUniversity of Wollongong Wollongong Australia
- Illawarra Health and Medical Research InstituteUniversity of Wollongong Wollongong Australia
- Australian Centre for Electromagnetic Bioeffects Research Wollongong Australia
- Centre for Population Health Research on Electromagnetic EnergyMonash University Melbourne Australia
| | - Alexandre Legros
- Lawson Health Research InstituteWestern University London Canada
| | - Rodney J. Croft
- School of PsychologyUniversity of Wollongong Wollongong Australia
- Illawarra Health and Medical Research InstituteUniversity of Wollongong Wollongong Australia
- Australian Centre for Electromagnetic Bioeffects Research Wollongong Australia
- Centre for Population Health Research on Electromagnetic EnergyMonash University Melbourne Australia
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Grissonnanche G, Legros A, Badoux S, Lefrançois E, Zatko V, Lizaire M, Laliberté F, Gourgout A, Zhou JS, Pyon S, Takayama T, Takagi H, Ono S, Doiron-Leyraud N, Taillefer L. Giant thermal Hall conductivity in the pseudogap phase of cuprate superconductors. Nature 2019; 571:376-380. [DOI: 10.1038/s41586-019-1375-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/26/2019] [Indexed: 11/09/2022]
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Modolo J, Hassan M, Legros A. Probing brain networks to quantify the consciousness level: which role for ELF brain stimulation? Brain Stimul 2019. [DOI: 10.1016/j.brs.2018.12.364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Legros A, Baker C, Corbacio M, Goulet D, Plante M, Souques M, Cabanes P, Deschamps F, Ostiguy G, Modolo J, Lambrozo J. Acute neurophysiological response to ELF-MF and magnetophosphene perception. Brain Stimul 2019. [DOI: 10.1016/j.brs.2018.12.670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Abstract
We assessed the effects of power-line frequency (60 Hz in North America) magnetic fields (MF) in humans using simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Twenty-five participants were enrolled in a pseudo-double-blind experiment involving "real" or "sham" exposure to sinusoidal 60 Hz MF exposures delivered using the gradient coil of an MRI scanner following two conditions: (i) 10 s exposures at 3 mT (10 repetitions); (ii) 2 s exposures at 7.6 mT (100 repetitions). Occipital EEG spectral power was computed in the alpha range (8-12 Hz, reportedly the most sensitive to MF exposure in the literature) with/without exposure. Brain functional activation was studied using fMRI blood oxygen level-dependent (BOLD, inversely correlated with EEG alpha power) maps. No significant effects were detected on occipital EEG alpha power during or post-exposure for any exposure condition. Consistent with EEG results, no effects were observed on fMRI BOLD maps in any brain region. Our results suggest that acute exposure (2-10 s) to 60 Hz MF from 3 to 7.6 mT (30,000 to 76,000 times higher than average public exposure levels for 60 Hz MF) does not induce detectable changes in EEG or BOLD signals. Combined with previous findings in which effects were observed on the BOLD signal after 1 h exposure to 3 mT, 60 Hz MF, this suggests that MF exposure in the low mT range (<10 mT) might require prolonged durations of exposure to induce detectable effects. Bioelectromagnetics. 38:425-435, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Julien Modolo
- Human Threshold Research and Bioelectromagnetics Group, Imaging Program, Lawson Health Research Institute, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada.,Institut National de la Santé et de la Recherche Médicale (INSERM), Rennes, France.,Laboratoire Traitement du Signal et de l'Image (LTSI), University of Rennes 1, LTSI, Rennes, France
| | - Alex W Thomas
- Human Threshold Research and Bioelectromagnetics Group, Imaging Program, Lawson Health Research Institute, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada
| | - Alexandre Legros
- Human Threshold Research and Bioelectromagnetics Group, Imaging Program, Lawson Health Research Institute, London, Canada.,Department of Medical Biophysics, Western University, London, Canada.,Department of Medical Imaging, Western University, London, Canada.,School of Kinesiology, Western University, London, Canada.,EuroMov, University of Montpellier, Montpellier, France
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Testaert H, Mombrun M, Klein S, Fouquet H, Gérard M, Legros A, Ray A, Auzary C, Jeanjean C, Geffray L. Rémission transitoire sous ibrutinib d’un syndrome de Bing-Neel au cours d’une maladie de Waldenström. Rev Med Interne 2017. [DOI: 10.1016/j.revmed.2017.03.300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Legros A, Modolo J, Corbacio M, Davarpanah Jazi S, Villard S, Goulet D, Plante M, Souques M, Deschamps F, Ostiguy G. Human acute neurophysiological responses to magnetically-induced alternating current densities of up to 100 mA.m-2. Brain Stimul 2017. [DOI: 10.1016/j.brs.2017.01.472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Legros A. Magnetophosphenes: an acute neurophysiological response to ELF-MF exposures. Int J Psychophysiol 2016. [DOI: 10.1016/j.ijpsycho.2016.07.204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Allen A, Corbacio M, Guerraz M, Goulet D, Plante M, Souques M, Deschamps F, Ostiguy G, Lambrozo J, Thomas A, Legros A. Étude des seuils de stimulations vestibulaires électriques et magnétiques modulant le contrôle postural. Neurophysiol Clin 2015. [DOI: 10.1016/j.neucli.2015.10.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Legros A, Modolo J, Brown S, Roberston J, Thomas AW. Effects of a 60 Hz Magnetic Field Exposure Up to 3000 μT on Human Brain Activation as Measured by Functional Magnetic Resonance Imaging. PLoS One 2015. [PMID: 26214312 PMCID: PMC4516358 DOI: 10.1371/journal.pone.0132024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Several aspects of the human nervous system and associated motor and cognitive processes have been reported to be modulated by extremely low-frequency (ELF, < 300 Hz) time-varying Magnetic Fields (MF). Due do their worldwide prevalence; power-line frequencies (60 Hz in North America) are of particular interest. Despite intense research efforts over the last few decades, the potential effects of 60 Hz MF still need to be elucidated, and the underlying mechanisms to be understood. In this study, we have used functional Magnetic Resonance Imaging (fMRI) to characterize potential changes in functional brain activation following human exposure to a 60 Hz MF through motor and cognitive tasks. First, pilot results acquired in a first set of subjects (N=9) were used to demonstrate the technical feasibility of using fMRI to detect subtle changes in functional brain activation with 60 Hz MF exposure at 1800 μT. Second, a full study involving a larger cohort of subjects tested brain activation during 1) a finger tapping task (N=20), and 2) a mental rotation task (N=21); before and after a one-hour, 60 Hz, 3000 μT MF exposure. The results indicate significant changes in task-induced functional brain activation as a consequence of MF exposure. However, no impact on task performance was found. These results illustrate the potential of using fMRI to identify MF-induced changes in functional brain activation, suggesting that a one-hour 60 Hz, 3000 μT MF exposure can modulate activity in specific brain regions after the end of the exposure period (i.e., residual effects). We discuss the possibility that MF exposure at 60 Hz, 3000 μT may be capable of modulating cortical excitability via a modulation of synaptic plasticity processes.
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Affiliation(s)
- Alexandre Legros
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
- * E-mail:
| | - Julien Modolo
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Samantha Brown
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
| | - John Roberston
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Alex W. Thomas
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- Department of Medical Imaging, Western University, London, Ontario, Canada
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Modolo J, Legros A, Beuter A. The next move in neuromodulation therapy: a question of timing. Front Comput Neurosci 2015; 8:162. [PMID: 25762920 PMCID: PMC4327509 DOI: 10.3389/fncom.2014.00162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 11/24/2014] [Indexed: 11/23/2022] Open
Affiliation(s)
- Julien Modolo
- Human Threshold Research Group, Lawson Health Research Institute London, ON, Canada ; Departments of Medical Biophysics and Medical Imaging, Western University London, ON, Canada
| | - Alexandre Legros
- Human Threshold Research Group, Lawson Health Research Institute London, ON, Canada ; Departments of Medical Biophysics and Medical Imaging, Western University London, ON, Canada ; School of Kinesiology, Western University London, ON, Canada
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Modolo J, Thomas AW, Legros A. Mechanism-based modeling of time-varying magnetic fields effects on cortical activity. BMC Neurosci 2014. [PMCID: PMC4124994 DOI: 10.1186/1471-2202-15-s1-p116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
Understanding the biological mechanisms by which extremely low-frequency (ELF, < 300 Hz) magnetic fields (MFs) interact with human brain activity is an active field of research. Such knowledge is required by international agencies providing guidelines for general public and workers exposure to ELF MFs (such as ICNIRP, the International Commission on Non-Ionizing Radiation Protection). The identification of these interaction mechanisms is extremely challenging, since the effects of ELF MF exposure need to be monitored and understood at very different spatial (from micrometers to centimeters) and temporal (from milliseconds to minutes) scales. One possibility to overcome these issues is to develop biophysical models, based on the systems of mathematical equations describing the electric or metabolic activity of the brain tissue. Biophysical models of the brain activity offer the possibility to simulate how the brain tissue interacts with ELF MFs, in order to gain new insights into experimental data, and to test novel hypotheses regarding interaction mechanisms. This paper presents novel hypotheses regarding the effects of power line (60 Hz in North America) MFs on human brain activity, with arguments from biophysical models. We suggest a hypothetic chain of events that could bridge MF exposure with detectable effects on human neurophysiology. We also suggest novel directions of research in order to reach a convergence of biophysical models of brain activity and corresponding experimental data to identify interaction mechanisms.
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Affiliation(s)
- Julien Modolo
- Human Threshold Research Group, Lawson Health Research Institute, London, ON, Canada.
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Modolo J, Thomas AW, Legros A. Neural mass modeling of power-line magnetic fields effects on brain activity. Front Comput Neurosci 2013; 7:34. [PMID: 23596412 PMCID: PMC3622877 DOI: 10.3389/fncom.2013.00034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/25/2013] [Indexed: 11/13/2022] Open
Abstract
Neural mass models are an appropriate framework to study brain activity, combining a high degree of biological realism while being mathematically tractable. These models have been used, with a certain success, to simulate brain electric (electroencephalography, EEG) and metabolic (functional magnetic resonance imaging, fMRI) activity. However, concrete applications of neural mass models have remained limited to date. Motivated by experimental results obtained in humans, we propose in this paper a neural mass model designed to study the interaction between power-line magnetic fields (MFs) (60 Hz in North America) and brain activity. The model includes pyramidal cells; dendrite-projecting, slow GABAergic neurons; soma-projecting, fast GABAergic neurons; and glutamatergic interneurons. A simple phenomenological model of interaction between the induced electric field and neuron membranes is also considered, along with a model of post-synaptic calcium concentration and associated changes in synaptic weights Simulated EEG signals are produced in a simple protocol, both in the absence and presence of a 60 Hz MF. These results are discussed based on results obtained previously in humans. Notably, results highlight that (1) EEG alpha (8-12 Hz) power can be modulated by weak membrane depolarizations induced by the exposure; (2) the level of input noise has a significant impact on EEG power modulation; and (3) the threshold value in MF flux density resulting in a significant effect on the EEG depends on the type of neuronal populations modulated by the MF exposure. Results obtained from the model shed new light on the effects of power-line MFs on brain activity, and will provide guidance in future human experiments. This may represent a valuable contribution to international regulation agencies setting guidelines on MF values to which the general public and workers can be exposed.
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Affiliation(s)
- J Modolo
- Human Threshold Research Group, Lawson Health Research Institute London, ON, Canada ; Department of Medical Biophysics, Western University London, ON, Canada ; Department of Medical Imaging, Western University London, ON, Canada
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Modolo J, Beuter A, Thomas AW, Legros A. Using "smart stimulators" to treat Parkinson's disease: re-engineering neurostimulation devices. Front Comput Neurosci 2012; 6:69. [PMID: 23060781 PMCID: PMC3448062 DOI: 10.3389/fncom.2012.00069] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 08/29/2012] [Indexed: 11/13/2022] Open
Abstract
Let's imagine the cruise control of your car locked at 120 km/h on any road in any condition (city, country, highway, sunny or rainy weather), or your car air conditioner set on maximum cold in any temperature condition (even during a snowy winter): would you find it efficient? That would probably not be the most optimal strategy for a proper and comfortable driving experience. As surprising as this may seem, this is a pretty accurate illustration of how deep brain stimulation is used today to treat Parkinson's disease motor symptoms and other neurological disorders such as essential tremor, obsessive-compulsive disorder, or epilepsy.
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Affiliation(s)
- Julien Modolo
- Bioelectromagnetics, Imaging Program, Lawson Health Research Institute London, ON, Canada ; Department of Medical Biophysics, The University of Western Ontario London, ON, Canada
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Legros A, Corbacio M, Beuter A, Modolo J, Goulet D, Prato FS, Thomas AW. Neurophysiological and behavioral effects of a 60 Hz, 1,800 μT magnetic field in humans. Eur J Appl Physiol 2011; 112:1751-62. [PMID: 21894451 DOI: 10.1007/s00421-011-2130-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 08/12/2011] [Indexed: 11/29/2022]
Abstract
The effects of time-varying magnetic fields (MF) on humans have been actively investigated for the past three decades. One important unanswered question is the potential for MF exposure to have acute effects on human biology. Different strategies have been used to tackle this question using various physiological, neurophysiological and behavioral indicators. For example, researchers investigating electroencephalography (EEG) have reported that extremely low frequency (ELF, <300 Hz) MF can increase resting occipital alpha rhythm (8-12 Hz). Interestingly, other studies have demonstrated that human motricity can be modulated by ELF MF: a reduction of anteroposterior standing balance or a decrease of physiological tremor intensity have been reported as consequences of exposure. However, the main limitation in this domain lies in the lack of results replication, possibly originating from the large variety of experimental approaches employed. Therefore, the present study aimed to investigate the effects of a 60 Hz, 1,800 μT MF exposure on neurophysiological (EEG) and neuromotor (standing balance, voluntary motor function, and physiological tremor) aspects in humans using a single experimental procedure. Though results from this study suggest a reduction of human standing balance with MF exposure, as well as an increase of physiological tremor amplitude within the frequency range associated with central nervous system contribution, no exposure effect appeared on other investigated parameters (e.g., EEG or voluntary motor control). These results suggest that 1 h of 60 Hz, 1,800 μT MF exposure may modulate human involuntary motor control without being detected in the cortical electrical activity.
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Affiliation(s)
- A Legros
- Imaging Division, Lawson Health Research Institute, St Joseph's Health Care, 268 Grosvenor St, London, ON N6A 4V2, Canada.
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Marshall HR, Stodilka RZ, Theberge J, Sabondjian E, Legros A, Deans L, Sykes JM, Thompson RT, Prato FS. A comparison of MR-based attenuation correction in PET versus SPECT. Phys Med Biol 2011; 56:4613-29. [PMID: 21725141 DOI: 10.1088/0031-9155/56/14/024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Attenuation correction (AC) is a critical step in the reconstruction of quantitatively accurate positron emission tomography (PET) and single photon emission computed tomography (SPECT) images. Several groups have proposed magnetic resonance (MR)-based AC algorithms for application in hybrid PET/MR systems. However, none of these approaches have been tested on SPECT data. Since SPECT/MR systems are under active development, it is important to ascertain whether MR-based AC algorithms validated for PET can be applied to SPECT. To investigate this issue, two imaging experiments were performed: one with an anthropomorphic chest phantom and one with two groups of canines. Both groups of canines were imaged from neck to abdomen, one with PET/CT and MR (n = 4) and the other with SPECT/CT and MR (n = 4), while the phantom was imaged with all modalities. The quality of the nuclear medicine reconstructions using MR-based attenuation maps was compared between PET and SPECT on global and local scales. In addition, the sensitivity of these reconstructions to variations in the attenuation map was ascertained. On both scales, it was found that the SPECT reconstructions were of higher fidelity than the PET reconstructions. Further, they were less sensitive to changes to the MR-based attenuation map. Thus, MR-based AC algorithms that have been designed for PET/MR can be expected to demonstrate improved performance when used for SPECT/MR.
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Affiliation(s)
- H R Marshall
- The Lawson Health Research Institute, Imaging Program, London, Ontario, Canada.
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Corbacio M, Brown S, Dubois S, Goulet D, Prato FS, Thomas AW, Legros A. Human cognitive performance in a 3 mT power-line frequency magnetic field. Bioelectromagnetics 2011; 32:620-33. [DOI: 10.1002/bem.20676] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 04/10/2011] [Indexed: 11/07/2022]
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Modolo J, Legros A, Thomas AW, Beuter A. Model-driven therapeutic treatment of neurological disorders: reshaping brain rhythms with neuromodulation. Interface Focus 2010; 1:61-74. [PMID: 22419974 DOI: 10.1098/rsfs.2010.0509] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 10/25/2010] [Indexed: 11/12/2022] Open
Abstract
Electric stimulation has been investigated for several decades to treat, with various degrees of success, a broad spectrum of neurological disorders. Historically, the development of these methods has been largely empirical but has led to a remarkably efficient, yet invasive treatment: deep brain stimulation (DBS). However, the efficiency of DBS is limited by our lack of understanding of the underlying physiological mechanisms and by the complex relationship existing between brain processing and behaviour. Biophysical modelling of brain activity, describing multi-scale spatio-temporal patterns of neuronal activity using a mathematical model and taking into account the physical properties of brain tissue, represents one way to fill this gap. In this review, we illustrate how biophysical modelling is beginning to emerge as a driving force orienting the development of innovative brain stimulation methods that may move DBS forward. We present examples of modelling works that have provided fruitful insights in regards to DBS underlying mechanisms, and others that also suggest potential improvements for this neurosurgical procedure. The reviewed literature emphasizes that biophysical modelling is a valuable tool to assist a rational development of electrical and/or magnetic brain stimulation methods tailored to both the disease and the patient's characteristics.
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Affiliation(s)
- Julien Modolo
- Lawson Health Research Institute, St Joseph Health Care , 268 Grosvenor Street, London , Canada
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Modolo J, Bhattacharya B, Edwards R, Campagnaud J, Legros A, Beuter A. Using a virtual cortical module implementing a neural field model to modulate brain rhythms in Parkinson's disease. Front Neurosci 2010; 4. [PMID: 20730081 PMCID: PMC2920509 DOI: 10.3389/fnins.2010.00045] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 06/08/2010] [Indexed: 11/13/2022] Open
Abstract
We propose a new method for selective modulation of cortical rhythms based on neural field theory, in which the activity of a cortical area is extensively monitored using a two-dimensional microelectrode array. The example of Parkinson's disease illustrates the proposed method, in which a neural field model is assumed to accurately describe experimentally recorded activity. In addition, we propose a new closed-loop stimulation signal that is both space- and time- dependent. This method is especially designed to specifically modulate a targeted brain rhythm, without interfering with other rhythms. A new class of neuroprosthetic devices is also proposed, in which the multielectrode array is seen as an artificial neural network interacting with biological tissue. Such a bio-inspired approach may provide a solution to optimize interactions between the stimulation device and the cortex aiming to attenuate or augment specific cortical rhythms. The next step will be to validate this new approach experimentally in patients with Parkinson's disease.
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Affiliation(s)
- Julien Modolo
- Department of Medical Biophysics, Lawson Health Research Institute, University of Western Ontario London, ON, Canada
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Pavlov AN, Tupitsyn AN, Legros A, Beuter A, Mosekilde E. Using wavelet analysis to detect the influence of low frequency magnetic fields on human physiological tremor. Physiol Meas 2007; 28:321-33. [PMID: 17322595 DOI: 10.1088/0967-3334/28/3/007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The influence of extremely low frequency magnetic fields (ELF-MFs) on human physiological processes and, in particular, on motor activity is still not established with certainty. Using the wavelet-transform approach, changes in the characteristics of human finger micromovement are studied in the presence of a low intensity MF centred at the level of the head. Different approaches to nonstationary signal analysis involving real as well as complex wavelet functions are considered. We find evidence that ELF-MFs lead to more regular postural tremor and more homogeneous energy distribution.
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Affiliation(s)
- A N Pavlov
- Department of Physics, Saratov State University, Astrakhanskaya Str 83, Saratov, Russia.
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Faure D, Maleville X, Hipeaux JC, Legros A. Oxydation des huiles de bases minérales d'origine pétrolière. Relation entre leur composition chimique, l'épaississement et la composition de leur produits de dégradation. ACTA ACUST UNITED AC 2006. [DOI: 10.2516/ogst:1995027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Legros A, Beuter A. Individual subject sensitivity to extremely low frequency magnetic field. Neurotoxicology 2006; 27:534-46. [PMID: 16620992 DOI: 10.1016/j.neuro.2006.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 03/30/2005] [Accepted: 02/16/2006] [Indexed: 11/19/2022]
Abstract
It is becoming important to specify the smallest effects of extremely low frequency (ELF) magnetic fields (MF) on human physiology. One difficulty is that some people seem more sensitive and more responsive than others to MF exposure. Consequently, within- and between-subject differences have to be taken into account when evaluating these effects. As shown in previous work, human postural tremor is sensitive to MF exposure. But data about individual responses have not been examined in detail. Thus, postural tremor of 24 subjects was evaluated under ELF MF "on" and "off" conditions in a double-blind real/sham exposure protocol. The direction of the tremor changes was analyzed individually for three tremor characteristics. Results showed that subjects with high amplitude tremor seem to be more responsive to MF exposure. MF had an instantaneous effect (between "on" and "off" conditions) and also a more delayed and persistent one (between real and sham conditions), but differences were small. Moreover, due to the within- and between-subject variability, no statistical analysis could be done. However, these results do not show any potentially harmful effect of domestic or industrial 50 Hz MF on humans. They provide a starting point to orient future studies and should be taken into account in the establishment of new exposure limits.
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Affiliation(s)
- Alexandre Legros
- Department of Imaging, Lawson Health Research Institute, St. Joseph's Health Care, 268 Grosvenor Street, London, Ont., Canada N6A 4V2.
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Abstract
INTRODUCTION Quantification of motor functions of patients with dystonic syndromes treated by chronic high frequency stimulation of the internal globulus pallidus is a challenge. OBJECTIVE Through a series of clinical examples this paper shows that kinematic analysis of movements in dystonic syndromes treated by deep brain stimulation (DBS) is a complement to clinical evaluation. In addition, it provides valuable information for early detection of improvement or impairment of movements associated with modifications of stimulation parameters. METHOD Thirteen dystonic patients and eleven reference subjects completed three tests (i.e., rest: lying supine; posture: standing with arms held in front (at shoulder height); and alternative movements: bimanual finger-to-nose test). These tests were recorded with an electromagnetic system quantifying movement kinematics (position) in three-dimensional space. RESULTS From the recorded data, several indices were developed and provided a quantitative evaluation of movements during each test. In addition, a clinical evaluation (BMFDRS) was also completed. No correlation between clinical and kinematic evaluations was found. CONCLUSION It is shown that kinematic analysis is a useful complement of clinical evaluation and can assist clinicians in monitoring the evolution of movements in dystonic patients treated by DBS in a simple, reliable and valid fashion.
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Affiliation(s)
- A Legros
- Equipe d'Accueil 2991: Efficience et Déficience Motrices, Montpellier
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Abstract
Extremely low frequency (ELF) magnetic fields (MF) are omnipresent in our modern daily environment, but their effects on humans are still not clearly established. The aim of this study was to determine the effect of a 50 Hz, 1,000 microT MF centered at the level of the head on human index finger micro-displacements. Twenty-four men recruited among the personnel of the French company, Electricité de France (EDF), completed the experiment. Their postural and kinetic tremors were recorded under four "field-on" and four "field-off" conditions, each tested during a real and a sham sequence. Eight postural and four kinetic tremor characteristics were calculated on recorded time series and were used for statistical analysis. No effect of the MF was found for kinetic tremor. Concerning postural tremor, the proportion of oscillations at low frequencies (between 2 and 4 Hz) was higher during the real than during the sham exposure sequence (P<.05). It suggests that MF could have a subtle delayed effect on human behavior, which is clearly not pathological. These results should be taken into account for the establishment of new exposure limits.
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Affiliation(s)
- Alexandre Legros
- UPRES EA 2991, Université de Montpellier I, URMA, Neurochirurgie B, Hopital Gui de Chauliac, Montpellier, France.
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Legros A, Diakonova N, Cif L, Hemm S, Vayssière N, Coubes P, Beuter A. Accelerometric measurement of involuntary movements during pallidal deep brain stimulation of patients with generalized dystonia. Brain Res Bull 2004; 64:363-9. [PMID: 15561472 DOI: 10.1016/j.brainresbull.2004.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2003] [Accepted: 09/13/2004] [Indexed: 10/26/2022]
Abstract
Accelerometric activity during rest and posture was quantified in the upper dominant limb of 14 patients with primary or secondary dystonia and five healthy control subjects. Data were recorded before and after bilateral implantation of the stimulating electrodes in the Globus Pallidus internus. Clinical evaluation was based on the Burke-Marsden-Fahn's Dystonia Rating Scale (BMFDRS). For the patient group, I(t), the integral (i.e. area) of the acceleration power spectrum over the total frequency range (0.6-16 Hz) decreased as the clinical state of the patients improved following deep brain stimulation (p < 0.01) during rest and posture. Ten days after surgery, there were no I(t) differences between control subjects and patients (p > 0.05). A significant correlation was found between the global BMFDRS scores and I(t) for rest (p < 0.01) but not for posture. No significant correlation was found between I(t) and a partial BMFDRS score for the right arm for rest or posture. The integral I(t) provides a valid indicator of the motor activity generated by the arm of the patient but further analyses are needed to monitor patients' progress not only during their hospitalization but also after they are released from the hospital, and to understand why this measure does not correlate with partial BMFDRS scores.
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Affiliation(s)
- A Legros
- Efficience et Déficience Motrice (EA 2991) and Department of Pediatric Neurosurgery (Research Unit on Movement Disorders in Children), University Hospital Gui de Chauliac, Montpellier, France
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Abstract
Quantifying movement disorders is becoming crucially important in neurosurgery units to evaluate the efficacy of new therapeutic interventions such as deep brain stimulation. Kinematic analysis, available for more than a century, may represent an adequate solution to this problem. However, quantifying movement disorders poses a number of technical problems. To help clinicians quantify movement disorders, the authors present data recorded in patients with dystonic syndromes and explore the question of movement "normality" in these patients when they receive deep brain stimulation of the internal globus pallidus. In particular, they show that when one control group (n = 11) and a group of dystonic patients (n = 11) are compared, it is possible to detect subtle changes in the performance of a double-handed finger to nose test. These differences persist in the absence of differences in the clinical evaluation of these patients. Suggestions regarding the compromises to make and pitfalls to avoid when quantifying movement disorders are discussed.
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Affiliation(s)
- Anne Beuter
- Movement Disorder Research Unit, Hòpital Gui de Chauliac, Université de Montpellier I, Montpellier, France.
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Delignières D, Deschamps T, Legros A, Caillou N. A methodological note on nonlinear time series analysis: is the open- and closed-loop model of Collins and De Luca (1993) a statistical artifact? J Mot Behav 2003; 35:86-97. [PMID: 12724102 DOI: 10.1080/00222890309602124] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The authors reexamined, theoretically and empirically, the method proposed by J. J. Collins and C. D. De Luca (1993) for the analysis of center-of-pressure trajectories. The main argument in this article is that Collins and De Luca's approach is not adapted to the analysis of bounded time series and leads to statistical artifacts such as underestimation of the diffusion process for long-term intervals. The open- and closed-loop model developed by Collins and De Luca is a direct consequence of those statistical problems. Applying more classical methods, such as rescaled range analysis or detrended fluctuation analysis, the authors show that center-of-pressure trajectories can be modeled as continuous, antipersistent fractional Brownian motion. More specifically, those trajectories behave like 1/f noise, a ubiquitous feature in adaptive biological systems.
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Affiliation(s)
- Didier Delignières
- Sport-Performance-Santé, Faculty des Sciences du Sport et de l'Education Physique, Université Montpellier, Montpellier, France.
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Faure D, Hipeaux JC, Guevellou Y, Legros A. Oxidation stability of gasoline engine lubricants: Effect of base-oil chemistry in laboratory and engine tests. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/tt.3020050402] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Legros A, Carreau P, Favis B, Michel A. Morphology modification by interfacial chemical reaction in a polyester/ethylene vinyl acetate/polyethylene blend. POLYMER 1997. [DOI: 10.1016/s0032-3861(97)00033-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Donandieu AM, Idee JM, Doucet D, Legros A, Penati S, Nain-Dit-Ducret M, Marmion F, Bonnemain B. Toxicologic profile of iobitridol, a new nonionic low-osmolality contrast medium. Acta Radiol Suppl 1996; 400:17-24. [PMID: 8619348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
PURPOSE The toxicologic profile of iobitridol, a new nonionic low-osomolality contrast medium, was evaluated in compliance with the current regulatory requirements in Europe, the USA and Canada. MATERIAL AND METHODS The toxicity of iobitridol was tested following acute or repeated i.v. administration in several different species (mouse, rat, dog); single oral administration in the mouse and intracisternal injection in the rat. Furthermore, teratogenicity and mutagenicity were evaluated in the rat and rabbit. Local perivenous toxicity was assessed in the rabbit. RESULTS The acute toxicity of iobitridol in the mouse is equivalent to that of iohexol, a reference product tested under the same conditions. Chronic administration (daily injections i.v. injection over 4 weeks) in the rat and dog did not demonstrate any particular toxicity for iobitridol. It should be noted that, unlike iohexol, iobitridol did not provoke any vacuolization of the renal tubular cells in the rat following repeated injections. Furthermore, this contrast agent did not show any teratogenic or mutagenic potential. The typical local inflammatory signs observed following perivenous injection in the rabbit were low in intensity and reversible. CONCLUSION The toxicologic profile of iobitridol appears to be favorable and does not show any particular risk for clinical use under the usual indications of water soluble iodinated contrast agents.
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Affiliation(s)
- A M Donandieu
- Research Center, Laboratoire Guerbet, Aulnay-sous-Bois, France
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Legros A, Carreau P, Favis B, Michel A. Reactive compatibilization of polyester/vinyl acetate copolymer blends: rheological, morphological and mechanical properties. POLYMER 1994. [DOI: 10.1016/0032-3861(94)90873-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Reux I, Legros A, Le Hoang P. [Preparation of the patient for ophthalmologic surgery]. Rev Infirm 1992; 42:30-3. [PMID: 1561518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Levy E, Parc R, Bloch P, Legros A, Hannoun L, Nordlinger B, Huguet C, Loygue J. [Transorificial intubation with direct neutralization of the digestive juices in cases of gastric or duodenal lesions. Principle and application of a new treatment for severe postoperative peritonitis of a gastric or duodenal origin (twenty-one cases) ]. Ann Chir 1982; 36:419-423. [PMID: 7125555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Legros A, Baux D, Leclère J, Malafosse M. [Echotomographic diagnosis of multiple abscesses of the kidney]. Nouv Presse Med 1981; 10:912. [PMID: 7208301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Benomar S, Bouziane M, Legros A, Ohayon V. [A new case of Dubin-Johnson disease]. Maghrib Tibbi 1980; 2:451-5. [PMID: 7345237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Legros A, Leconte D, Huguet C. [Intestinal pseudo-obstruction due to ganglioneuromatosis (author's transl)]. Gastroenterol Clin Biol 1980; 4:333-7. [PMID: 7399200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Loygue J, Michot F, Legros A. [Repair of perineal eventration following excision of the rectum, using the lumbo-ovarian ligaments]. Nouv Presse Med 1979; 8:3897. [PMID: 548919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Parc R, Legros A, Huguet C, Malafosse M, Bloch P, Gallot D, Loygue J. [Hepatic embolizations and dearterializations. Apropos of 32 cases]. Ann Chir 1978; 32:713-9. [PMID: 749657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Malafosse M, Legros A. [Treatment and prognosis of gastric adenocarcinoma]. Rev Prat 1978; 28:3485-92. [PMID: 82992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Blondeau P, Legros A, René L. [Is unilateral total lobectomy adequate treatment for a single malignant thyroid nodule? 67 patients operated upon between 5 and 18 years age (author's transl)]. Nouv Presse Med 1977; 6:2583-7. [PMID: 333385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the treatment of thyroid carcinoma, there is still some discussion about the best operation for a solitary and well encapsulated nodule. 18 years ago, it was decided to treat every case of "cold" thyroid nodule by total lobectomy and isthmectomy. 56 patients were reevaluated 5 to 18 years after such limited operation for malignant nodules. 8 of them died between the 19 th month and the 14 th year after surgery, the death being possibly related to the thyroid cancer in only 4 patients, but without any clinical evidence of local recurrence. Among 50 surviving patients, only one controlateral recurrence was observed, two years after lobectomy; it was treated by surgical totalisation of thyroidectomy, without any new recurrence after 10 more years. These results (although the small number of cases, and too short follow-up exclude definitive conclusions) are comparable to those obtained by a more aggresive surgical approach, but have the great advantage of total absence of any functional sequellae. So are we encouraged to go further in the experience of a rather conservative surgery in the treatment of uninodular thyroid carcinoma.
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Blondeau P, Legros A, Rene L. [The hemorrhagic risk in surgery of the thyroid gland]. Ann Chir 1975; 29:519-27. [PMID: 1163967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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