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Dmytriw AA, Hadjinicolaou A, Ntolkeras G, Tamilia E, Pesce M, Berto LF, Grant PE, Pang E, Ahtam B. Magnetoencephalography for the pediatric population, indications, acquisition and interpretation for the clinician. Neuroradiol J 2024:19714009241260801. [PMID: 38864180 DOI: 10.1177/19714009241260801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024] Open
Abstract
Magnetoencephalography (MEG) is an imaging technique that enables the assessment of cortical activity via direct measures of neurophysiology. It is a non-invasive and passive technique that is completely painless. MEG has gained increasing prominence in the field of pediatric neuroimaging. This dedicated review article for the pediatric population summarizes the fundamental technical and clinical aspects of MEG for the clinician. We discuss methods tailored for children to improve data quality, including child-friendly MEG facility environments and strategies to mitigate motion artifacts. We provide an in-depth overview on accurate localization of neural sources and different analysis methods, as well as data interpretation. The contemporary platforms and approaches of two quaternary pediatric referral centers are illustrated, shedding light on practical implementations in clinical settings. Finally, we describe the expanding clinical applications of MEG, including its pivotal role in presurgical evaluation of epilepsy patients, presurgical mapping of eloquent cortices (somatosensory and motor cortices, visual and auditory cortices, lateralization of language), its emerging relevance in autism spectrum disorder research and potential future clinical applications, and its utility in assessing mild traumatic brain injury. In conclusion, this review serves as a comprehensive resource of clinicians as well as researchers, offering insights into the evolving landscape of pediatric MEG. It discusses the importance of technical advancements, data acquisition strategies, and expanding clinical applications in harnessing the full potential of MEG to study neurological conditions in the pediatric population.
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Affiliation(s)
- Adam A Dmytriw
- Department of Radiology, Boston Children's Hospital, Boston, MA, USA
- Division of Neuroradiology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Aristides Hadjinicolaou
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Department of Neurology, Division of Epilepsy and Clinical Neurophysiology, Boston Children's Hospital, Boston, MA, USA
| | - Georgios Ntolkeras
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
| | - Eleonora Tamilia
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
| | - Matthew Pesce
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
| | - Laura F Berto
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
| | - P Ellen Grant
- Department of Radiology, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
| | - Elizabeth Pang
- Division of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Banu Ahtam
- Department of Pediatrics, Division of Newborn Medicine, Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, MA, USA
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Xu Z, Li F, Ma W, Yang K, Luo J, Zhang J, Wang X. The six-degrees-of-freedom attitude measurement instrument for the large aperture mirror using the prepressing sensors and flexible supporting. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:115104. [PMID: 37934037 DOI: 10.1063/5.0167171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/19/2023] [Indexed: 11/08/2023]
Abstract
To achieve precise measurement of a large aperture mirror, a six-degrees-of-freedom (6-DOF) measurement instrument is designed to monitor and calculate the real-time attitude of the mirror. Magnetoelectric displacement sensors are prepressed, and a flexible sensor supporting is designed to achieve high-accuracy measurement. The relationship between 6-DOF displacements of the mirror and the six sensor values can be obtained using the coordinate system transformation and Jacobian matrix. The Newton's iteration method is used to decouple the strong coupling measurement system, and 6-DOF displacements are obtained. The displacements directly measured by using laser sensors are compared with the calculated values in the experiments, the minimum average error of the measured displacement is 1.87%, and the mean difference of the displacement is 0.43 µm.
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Affiliation(s)
- Zhenyuan Xu
- Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
| | - Fei Li
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Wenjing Ma
- Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
| | - Kaike Yang
- Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
| | - Junpeng Luo
- Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
| | - Junwei Zhang
- Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China
| | - Xi Wang
- School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, China
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Zhang Z, He A, Xu Z, Yang K, Kong X. Neuromuscular Magnetic Field Measurement Based on Superconducting Bio-Sensors. MICROMACHINES 2023; 14:1768. [PMID: 37763931 PMCID: PMC10535156 DOI: 10.3390/mi14091768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/08/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023]
Abstract
These years, disease-causing and disabling diseases have caused great concern. Neurological musculoskeletal disorders are diverse and affect people of a wide range of ages. And the lack of comprehensive diagnostic methods places a huge burden on healthcare systems and social economies. In this paper, the current status of clinical research on neuromuscular diseases is introduced, and the advantages of magnetic field measurement compared with clinical diagnostic methods are illustrated. A comprehensive description of the related technology of superconducting quantum interference devices (SQUIDs), magnetic field detection noise suppression scheme, the development trend of the sensor detection system, and the application and model establishment of the neuromuscular magnetic field is also given in this paper. The current research and development trends worldwide are compared simultaneously, and finally the conclusions and outlook are put forward. Based on the description of the existing literature and the ideas of other researchers, the next development trends and my own research ideas are presented in this paper, that is, starting from the establishment of a neuromuscular model, combining medical and industrial work, designing a sensor system that meets clinical needs, and laying the foundation for the clinical application of a bio-magnetic system. This review promotes a combination between medicine and industry, and guides researchers on considering the challenges of sensor development in terms of clinical needs. In addition, in this paper, the development trends are described, including the establishment of the model, the clinical demand for sensors, and the challenges of system development so as to give certain guidance to researchers.
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Affiliation(s)
- Zhidan Zhang
- The Institute for Future Wireless Research (iFWR), Ningbo University, Ningbo 315211, China; (Z.Z.); (A.H.); (K.Y.)
- The Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
| | - Anran He
- The Institute for Future Wireless Research (iFWR), Ningbo University, Ningbo 315211, China; (Z.Z.); (A.H.); (K.Y.)
- The Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
| | - Zihan Xu
- The Institute for Future Wireless Research (iFWR), Ningbo University, Ningbo 315211, China; (Z.Z.); (A.H.); (K.Y.)
- The Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
| | - Kun Yang
- The Institute for Future Wireless Research (iFWR), Ningbo University, Ningbo 315211, China; (Z.Z.); (A.H.); (K.Y.)
- The Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
| | - Xiangyan Kong
- The Institute for Future Wireless Research (iFWR), Ningbo University, Ningbo 315211, China; (Z.Z.); (A.H.); (K.Y.)
- The Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo 315211, China
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Frohlich J, Bayne T, Crone JS, DallaVecchia A, Kirkeby-Hinrup A, Mediano PA, Moser J, Talar K, Gharabaghi A, Preissl H. Not with a “zap” but with a “beep”: measuring the origins of perinatal experience. Neuroimage 2023; 273:120057. [PMID: 37001834 DOI: 10.1016/j.neuroimage.2023.120057] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
When does the mind begin? Infant psychology is mysterious in part because we cannot remember our first months of life, nor can we directly communicate with infants. Even more speculative is the possibility of mental life prior to birth. The question of when consciousness, or subjective experience, begins in human development thus remains incompletely answered, though boundaries can be set using current knowledge from developmental neurobiology and recent investigations of the perinatal brain. Here, we offer our perspective on how the development of a sensory perturbational complexity index (sPCI) based on auditory ("beep-and-zip"), visual ("flash-and-zip"), or even olfactory ("sniff-and-zip") cortical perturbations in place of electromagnetic perturbations ("zap-and-zip") might be used to address this question. First, we discuss recent studies of perinatal cognition and consciousness using techniques such as functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and, in particular, magnetoencephalography (MEG). While newborn infants are the archetypal subjects for studying early human development, researchers may also benefit from fetal studies, as the womb is, in many respects, a more controlled environment than the cradle. The earliest possible timepoint when subjective experience might begin is likely the establishment of thalamocortical connectivity at 26 weeks gestation, as the thalamocortical system is necessary for consciousness according to most theoretical frameworks. To infer at what age and in which behavioral states consciousness might emerge following the initiation of thalamocortical pathways, we advocate for the development of the sPCI and similar techniques, based on EEG, MEG, and fMRI, to estimate the perinatal brain's state of consciousness.
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Llinás RR, Rykunov S, Walton KD, Boyko A, Ustinin M. Splitting of the magnetic encephalogram into «brain» and «non-brain» physiological signals based on the joint analysis of frequency-pattern functional tomograms and magnetic resonance images. Front Neural Circuits 2022; 16:834434. [PMID: 36092277 PMCID: PMC9458866 DOI: 10.3389/fncir.2022.834434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
The article considers the problem of dividing the encephalography data into two time series, that generated by the brain and that generated by other electrical sources located in the human head. The magnetic encephalograms and magnetic resonance images of the head were recorded in the Center for Neuromagnetism at NYU Grossman School of Medicine. Data obtained at McGill University and Montreal University were also used. Recordings were made in a magnetically shielded room and the gradiometers were designed to suppress external noise, making it possible to eliminate them from the data analysis. Magnetic encephalograms were analyzed by the method of functional tomography, based on the Fourier transform and on the solution of inverse problem for all frequencies. In this method, one spatial position is assigned to each frequency component. Magnetic resonance images of the head were evaluated to annotate the space to be included in the analysis. The included space was divided into two parts: «brain» and «non-brain». The frequency components were classified by the feature of their inclusion in one or the other part. The set of frequencies, designated as «brain», represented the partial spectrum of the brain signal, while the set of frequencies designated as «non-brain», represented the partial spectrum of the physiological noise produced by the head. Both partial spectra shared the same frequency band. From the partial spectra, a time series of the «brain» area signal and «non-brain» area head noise were reconstructed. Summary spectral power of the signal was found to be ten times greater than the noise. The proposed method makes it possible to analyze in detail both the signal and the noise components of the encephalogram and to filter the magnetic encephalogram.
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Affiliation(s)
- Rodolfo R. Llinás
- Department of Neuroscience, Center for Neuromagnetism, New York University Grossman School of Medicine, New York, NY, United States
| | - Stanislav Rykunov
- Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, Russia
- *Correspondence: Stanislav Rykunov,
| | - Kerry D. Walton
- Department of Neuroscience, Center for Neuromagnetism, New York University Grossman School of Medicine, New York, NY, United States
| | - Anna Boyko
- Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, Russia
| | - Mikhail Ustinin
- Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Moscow, Russia
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Affiliation(s)
- Elysa Widjaja
- From the Department of Diagnostic Imaging, Hospital for Sick Children, 555 University Ave, Toronto, ON, Canada M5G 1X8
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7
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Zahran S, Mahmoudzadeh M, Wallois F, Betrouni N, Derambure P, Le Prado M, Palacios-Laloy A, Labyt E. Performance Analysis of Optically Pumped 4He Magnetometers vs. Conventional SQUIDs: From Adult to Infant Head Models. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22083093. [PMID: 35459077 PMCID: PMC9024855 DOI: 10.3390/s22083093] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/30/2022] [Accepted: 04/08/2022] [Indexed: 05/27/2023]
Abstract
Optically pumped magnetometers (OPMs) are new, room-temperature alternatives to superconducting quantum interference devices (SQUIDs) for measuring the brain's magnetic fields. The most used OPM in MagnetoEncephaloGraphy (MEG) are based on alkali atoms operating in the spin-exchange relaxation-free (SERF) regime. These sensors do not require cooling but have to be heated. Another kind of OPM, based on the parametric resonance of 4He atoms are operated at room temperature, suppressing the heat dissipation issue. They also have an advantageous bandwidth and dynamic range more suitable for MEG recordings. We quantitatively assessed the improvement (relative to a SQUID magnetometers array) in recording the magnetic field with a wearable 4He OPM-MEG system through data simulations. The OPM array and magnetoencephalography forward models were based on anatomical MRI data from an adult, a nine-year-old child, and 10 infants aged between one month and two years. Our simulations showed that a 4He OPMs array offers markedly better spatial specificity than a SQUID magnetometers array in various key performance areas (e.g., signal power, information content, and spatial resolution). Our results are also discussed regarding previous simulation results obtained for alkali OPM.
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Affiliation(s)
- Saeed Zahran
- INSERM, U1105, GRAMFC, Université de Picardie Jules Verne, CHU Sud, 80000 Amiens, France; (S.Z.); (M.M.); (F.W.)
| | - Mahdi Mahmoudzadeh
- INSERM, U1105, GRAMFC, Université de Picardie Jules Verne, CHU Sud, 80000 Amiens, France; (S.Z.); (M.M.); (F.W.)
| | - Fabrice Wallois
- INSERM, U1105, GRAMFC, Université de Picardie Jules Verne, CHU Sud, 80000 Amiens, France; (S.Z.); (M.M.); (F.W.)
| | - Nacim Betrouni
- INSERM, U1172, CHU de Lille, Université de Lille, Degenerative & Vascular Cognitive Disorders, 59000 Lille, France; (N.B.); (P.D.)
| | - Philippe Derambure
- INSERM, U1172, CHU de Lille, Université de Lille, Degenerative & Vascular Cognitive Disorders, 59000 Lille, France; (N.B.); (P.D.)
| | - Matthieu Le Prado
- Laboratoire d’Electronique et de Technologies de l’Information, CEA, 38054 Grenoble, France; (M.L.P.); (A.P.-L.)
- Mag4health, 9 Avenue Paul Verlaine, 38000 Grenoble, France
| | - Agustin Palacios-Laloy
- Laboratoire d’Electronique et de Technologies de l’Information, CEA, 38054 Grenoble, France; (M.L.P.); (A.P.-L.)
| | - Etienne Labyt
- Laboratoire d’Electronique et de Technologies de l’Information, CEA, 38054 Grenoble, France; (M.L.P.); (A.P.-L.)
- CEA Tech Hauts de France, 59000 Lille, France
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8
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Clarke MD, Larson E, Peterson ER, McCloy DR, Bosseler AN, Taulu S. Improving Localization Accuracy of Neural Sources by Pre-processing: Demonstration With Infant MEG Data. Front Neurol 2022; 13:827529. [PMID: 35401424 PMCID: PMC8983818 DOI: 10.3389/fneur.2022.827529] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 01/31/2022] [Indexed: 11/25/2022] Open
Abstract
We discuss specific challenges and solutions in infant MEG, which is one of the most technically challenging areas of MEG studies. Our results can be generalized to a variety of challenging scenarios for MEG data acquisition, including clinical settings. We cover a wide range of steps in pre-processing, including movement compensation, suppression of magnetic interference from sources inside and outside the magnetically shielded room, suppression of specific physiological artifact components such as cardiac artifacts. In the assessment of the outcome of the pre-processing algorithms, we focus on comparing signal representation before and after pre-processing and discuss the importance of the different components of the main processing steps. We discuss the importance of taking the noise covariance structure into account in inverse modeling and present the proper treatment of the noise covariance matrix to accurately reflect the processing that was applied to the data. Using example cases, we investigate the level of source localization error before and after processing. One of our main findings is that statistical metrics of source reconstruction may erroneously indicate that the results are reliable even in cases where the data are severely distorted by head movements. As a consequence, we stress the importance of proper signal processing in infant MEG.
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Affiliation(s)
- Maggie D. Clarke
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
| | - Eric Larson
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
| | - Erica R. Peterson
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
| | - Daniel R. McCloy
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
| | - Alexis N. Bosseler
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
| | - Samu Taulu
- Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, United States
- Department of Physics, University of Washington, Seattle, WA, United States
- *Correspondence: Samu Taulu
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Bosch-Bayard J, Biscay RJ, Fernandez T, Otero GA, Ricardo-Garcell J, Aubert-Vazquez E, Evans AC, Harmony T. EEG effective connectivity during the first year of life mirrors brain synaptogenesis, myelination, and early right hemisphere predominance. Neuroimage 2022; 252:119035. [PMID: 35218932 DOI: 10.1016/j.neuroimage.2022.119035] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/25/2021] [Accepted: 02/22/2022] [Indexed: 10/19/2022] Open
Abstract
INTRODUCTION The maturation of electroencephalogram (EEG) effective connectivity in healthy infants during the first year of life is described. METHODS Participants: A cross-sectional sample of 125 healthy at-term infants, from 0 to 12 months of age, underwent EEG in a state of quiet sleep. PROCEDURES The EEG primary currents at the source were described with the sLoreta method. An unmixing algorithm was applied to reduce the leakage, and the isolated effective coherence, a direct and directed measurement of information flow, was calculated. RESULTS AND DISCUSSION Initially, the highest indices of connectivity are at the subcortical nuclei, continuing to the parietal lobe, predominantly the right hemisphere, then expanding to temporal, occipital, and finally the frontal areas, which is consistent with the myelination process. Age-related connectivity changes were mostly long-range and bilateral. Connections increased with age, mainly in the right hemisphere, while they mainly decreased in the left hemisphere. Increased connectivity from 20 to 30 Hz, mostly at the right hemisphere. These findings were consistent with right hemisphere predominance during the first three years of life. Theta and alpha connections showed the greatest changes with age. Strong connectivity was found between the parietal, temporal, and occipital regions to the frontal lobes, responsible for executive functions and consistent with behavioral development during the first year. The thalamus exchanges information bidirectionally with all cortical regions and frequency bands. CONCLUSIONS The maturation of EEG connectivity during the first year in healthy infants is very consistent with synaptogenesis, reductions in synaptogenesis, myelination, and functional and behavioral development.
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Affiliation(s)
- Jorge Bosch-Bayard
- McGill Center for Integrative Neuroscience (MCIN), Ludmer Center for Neuroinformatics and Mental Health, Montreal Neurological Institute (MNI), McGill University, Montreal H3A2B4, Canada
| | - Rolando J Biscay
- Centro de Investigación en Matemáticas, Guanajuato 36023, Mexico
| | - Thalia Fernandez
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Boulevard Juriquilla 3001, Querétaro 76230, Mexico
| | - Gloria A Otero
- Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca de Lerdo 50180, Mexico
| | - Josefina Ricardo-Garcell
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Boulevard Juriquilla 3001, Querétaro 76230, Mexico
| | | | - Alan C Evans
- McGill Center for Integrative Neuroscience (MCIN), Ludmer Center for Neuroinformatics and Mental Health, Montreal Neurological Institute (MNI), McGill University, Montreal H3A2B4, Canada
| | - Thalia Harmony
- Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México Campus Juriquilla, Boulevard Juriquilla 3001, Querétaro 76230, Mexico.
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10
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Tierney TM, Alexander N, Mellor S, Holmes N, Seymour R, O'Neill GC, Maguire EA, Barnes GR. Modelling optically pumped magnetometer interference in MEG as a spatially homogeneous magnetic field. Neuroimage 2021; 244:118484. [PMID: 34418526 DOI: 10.1016/j.neuroimage.2021.118484] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/19/2021] [Accepted: 08/18/2021] [Indexed: 11/24/2022] Open
Abstract
Here we propose that much of the magnetic interference observed when using optically pumped magnetometers for MEG experiments can be modeled as a spatially homogeneous magnetic field. We show that this approximation reduces sensor level variance and substantially improves statistical power. This model does not require knowledge of the underlying neuroanatomy nor the sensor positions. It only needs information about the sensor orientation. Due to the model's low rank there is little risk of removing substantial neural signal. However, we provide a framework to assess this risk for any sensor number, design or subject neuroanatomy. We find that the risk of unintentionally removing neural signal is reduced when multi-axis recordings are performed. We validated the method using a binaural auditory evoked response paradigm and demonstrated that removing the homogeneous magnetic field increases sensor level SNR by a factor of 3. Considering the model's simplicity and efficacy, we suggest that this homogeneous field correction can be a powerful preprocessing step for arrays of optically pumped magnetometers.
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Affiliation(s)
- Tim M Tierney
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK.
| | - Nicholas Alexander
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
| | - Stephanie Mellor
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
| | - Niall Holmes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Robert Seymour
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
| | - George C O'Neill
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
| | - Eleanor A Maguire
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
| | - Gareth R Barnes
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, 12 Queen Square, London WC1N 3AR, UK
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11
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Chen Y, Slinger M, Edgar JC, Bloy L, Kuschner ES, Kim M, Green HL, Chiang T, Yount T, Liu S, Lebus J, Lam S, Stephen JM, Huang H, Roberts TPL. Maturation of hemispheric specialization for face encoding during infancy and toddlerhood. Dev Cogn Neurosci 2021; 48:100918. [PMID: 33571846 PMCID: PMC7876542 DOI: 10.1016/j.dcn.2021.100918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 12/28/2020] [Accepted: 01/08/2021] [Indexed: 11/30/2022] Open
Abstract
Using infant magnetoencephalography (MEG), study findings show maturational changes to fusiform gyrus (FFG) activity when viewing faces. Earlier right FFG activity to face stimuli is associated with better social and cognitive ability. Stronger right- than left-hemisphere FFG responses to face stimuli are most evident after 1 year of age.
Little is known about the neural processes associated with attending to social stimuli during infancy and toddlerhood. Using infant magnetoencephalography (MEG), fusiform gyrus (FFG) activity while processing Face and Non-Face stimuli was examined in 46 typically developing infants 3 to 24 months old (28 males). Several findings indicated FFG maturation throughout the first two years of life. First, right FFG responses to Face stimuli decreased as a function of age. Second, hemispheric specialization to the face stimuli developed somewhat slowly, with earlier right than left FFG peak activity most evident after 1 year of age. Right FFG activity to Face stimuli was of clinical interest, with an earlier right FFG response associated with better performance on tests assessing social and cognitive ability. Building on the above, clinical studies examining maturational change in FFG activity (e.g., lateralization and speed) in infants at-risk for childhood disorders associated with social deficits are of interest to identify atypical FFG maturation before a formal diagnosis is possible.
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Affiliation(s)
- Yuhan Chen
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
| | - Michelle Slinger
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - J Christopher Edgar
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Luke Bloy
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Emily S Kuschner
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mina Kim
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Heather L Green
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Taylor Chiang
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Tess Yount
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Song Liu
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Jill Lebus
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Samantha Lam
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Julia M Stephen
- The Mind Research Network and Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA
| | - Hao Huang
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Timothy P L Roberts
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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12
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Lew S, Hämäläinen MS, Ahlfors SP, Okada Y. Influence of unfused cranial bones on magnetoencephalography signals in human infants. Clin Neurophysiol 2020; 132:708-719. [PMID: 33571879 DOI: 10.1016/j.clinph.2020.11.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 11/12/2020] [Accepted: 11/17/2020] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To clarify the effects of unfused cranial bones on magnetoencephalography (MEG) signals during early development. METHODS In a simulation study, we compared the MEG signals over a spherical head model with a circular hole mimicking the anterior fontanel to those over the same head model without the fontanel for different head and fontanel sizes with varying skull thickness and conductivity. RESULTS The fontanel had small effects according to three indices. The sum of differences in signal over a sensor array due to a fontanel, for example, was < 6% of the sum without the fontanel. However, the fontanel effects were extensive for dipole sources deep in the brain or outside the fontanel for larger fontanels. The effects were comparable in magnitude for tangential and radial sources. Skull thickness significantly increased the effect, while skull conductivity had minor effects. CONCLUSION MEG signal is weakly affected by a fontanel. However, the effects can be extensive and significant for radial sources, thicker skull and large fontanels. The fontanel effects can be intuitively explained by the concept of secondary sources at the fontanel wall. SIGNIFICANCE The minor influence of unfused cranial bones simplifies MEG analysis, but it should be considered for quantitative analysis.
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Affiliation(s)
- Seok Lew
- Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Matti S Hämäläinen
- Harvard Medical School, Boston, MA 02115, USA; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Seppo P Ahlfors
- Harvard Medical School, Boston, MA 02115, USA; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA
| | - Yoshio Okada
- Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA.
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13
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Zhu B, Sevick-Muraca EM, Nguyen RD, Shah MN. Cap-Based Transcranial Optical Tomography in an Awake Infant. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:3300-3308. [PMID: 32356740 DOI: 10.1109/tmi.2020.2990823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although Blood Oxygenation Level Dependent (BOLD) functional MRI (fMRI) is widely used to examine brain function in adults, the need for general anesthesia limits its practical utility in infants and small children. Functional Near-Infrared Spectroscopy - Diffuse Optical Tomography (fNIRS-DOT) imaging promises to be an alternative brain network imaging technique. Yet current versions of continuous-wave fNIRS-DOT systems are restricted to the cortical surface measurements and do not probe deep structures that are frequently injured especially in premature infants. Herein we report a transcranial near infrared optical imaging system, called Cap-based Transcranial Optical Tomography (CTOT) able to image whole brain hemodynamic activity with 3 seconds of data acquisition time. We show the system is capable of whole brain oxygenation mapping in an awake child, and that tomographically reconstructed static CTOT-derived oxy- and deoxygenated blood volumes are spatially correlated with the time-averaged BOLD fMRI volumes. By removing time bottlenecks in the current system, dynamic CTOT mapping should be possible, which would then enable evaluation of functional connectivity in awake infants.
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14
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Auditory Mapping With MEG: An Update on the Current State of Clinical Research and Practice With Considerations for Clinical Practice Guidelines. J Clin Neurophysiol 2020; 37:574-584. [DOI: 10.1097/wnp.0000000000000518] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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15
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Abstract
Concise history of fascinating magnetoencephalography (MEG) technology and catalog of very selected milestone preclinical and clinical MEG studies are provided as the background. The focus is the societal context defining a journey of MEG to and through clinical practice and formation of the American Clinical MEG Society (ACMEGS). We aspired to provide an objective historic perspective and document contributions of many professionals while focusing on the role of ACMEGS in the growth and maturation of clinical MEG field. The ACMEGS was born (2006) out of inevitability to address two vital issues-fair reimbursement and proper clinical acceptance. A beacon of accountable MEG practice and utilization is now an expanding professional organization with the highest level of competence in practice of clinical MEG and clinical credibility. The ACMEGS facilitated a favorable disposition of insurances toward MEG in the United States by combining the national replication of the grassroots efforts and teaming up with the strategic partners-particularly the American Academy of Neurology (AAN), published two Position Statements (2009 and 2017), the world's only set of MEG Clinical Practice Guidelines (CPGs; 2011) and surveys of clinical MEG practice (2011 and 2020) and use (2020). In addition to the annual ACMEGS Course (2012), we directly engaged MEG practitioners through an Invitational Summit (2019). The Society remains focused on the improvements and expansion of clinical practice, education, clinical training, and constructive engagement of vendors in these issues and pivotal studies toward additional MEG indications. The ACMEGS not only had the critical role in the progress of Clinical MEG in the United States and beyond since 2006 but positioned itself as the field leader in the future.
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16
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Okada Y, Khan S, Curran A, Ahtam B, Hämäläinen MS, Traub RD, Pearl PL. Epileptic Activity Intrinsically Generated in the Human Cerebellum. Ann Neurol 2020; 88:418-422. [PMID: 32421204 DOI: 10.1002/ana.25779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 04/21/2020] [Accepted: 05/10/2020] [Indexed: 11/06/2022]
Abstract
Neoplastic or dysplastic neuronal tissue in the brain stem and cerebellum can become epileptogenic in pediatric patients. However, it is unknown whether such tissue may transform intrinsic properties of the human cerebellum, making it capable of generating epileptic population activity. We noninvasively detected epileptiform signals unaveraged in a pediatric patient with epilepsy due to a tumor in the middle cerebellar peduncle. Analysis of generators of the signals revealed that the cerebellum ipsilateral and contralateral to the tumor was the dominant interictal spike generator and could initiate ictal activity, suggesting that human cerebellum may become capable of intrinsically generating epileptic activity. ANN NEUROL 2020;88:418-422.
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Affiliation(s)
- Yoshio Okada
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Sheraz Khan
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
| | - Ashley Curran
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Banu Ahtam
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Matti S Hämäläinen
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA
| | - Roger D Traub
- AI Foundations, IBM T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Phillip L Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
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17
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Pfeiffer C, Ruffieux S, Jonsson L, Chukharkin ML, Kalaboukhov A, Xie M, Winkler D, Schneiderman JF. A 7-Channel High-${T}_\text{c}$ SQUID-Based On-Scalp MEG System. IEEE Trans Biomed Eng 2020; 67:1483-1489. [DOI: 10.1109/tbme.2019.2938688] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Abstract
Magnetoencephalography (MEG) is a noninvasive neuroimaging technique that measures the electromagnetic fields generated by the human brain. This article highlights the benefits that pediatric MEG has to offer to clinical practice and pediatric research, particularly for infants and young children; reviews the existing literature on adult MEG systems for pediatric use; briefly describes the few pediatric MEG systems currently extant; and draws attention to future directions of research, with focus on the clinical use of MEG for patients with drug-resistant epilepsy.
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19
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Borna A, Carter TR, Colombo AP, Jau YY, McKay J, Weisend M, Taulu S, Stephen JM, Schwindt PDD. Non-Invasive Functional-Brain-Imaging with an OPM-based Magnetoencephalography System. PLoS One 2020; 15:e0227684. [PMID: 31978102 PMCID: PMC6980641 DOI: 10.1371/journal.pone.0227684] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/25/2019] [Indexed: 12/14/2022] Open
Abstract
A non-invasive functional-brain-imaging system based on optically-pumped-magnetometers (OPM) is presented. The OPM-based magnetoencephalography (MEG) system features 20 OPM channels conforming to the subject's scalp. We have conducted two MEG experiments on three subjects: assessment of somatosensory evoked magnetic field (SEF) and auditory evoked magnetic field (AEF) using our OPM-based MEG system and a commercial MEG system based on superconducting quantum interference devices (SQUIDs). We cross validated the robustness of our system by calculating the distance between the location of the equivalent current dipole (ECD) yielded by our OPM-based MEG system and the ECD location calculated by the commercial SQUID-based MEG system. We achieved sub-centimeter accuracy for both SEF and AEF responses in all three subjects. Due to the proximity (12 mm) of the OPM channels to the scalp, it is anticipated that future OPM-based MEG systems will offer enhanced spatial resolution as they will capture finer spatial features compared to traditional MEG systems employing SQUIDs.
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Affiliation(s)
- Amir Borna
- Sandia National Laboratories, Albuquerque, NM, United States of America
- * E-mail:
| | - Tony R. Carter
- Sandia National Laboratories, Albuquerque, NM, United States of America
| | | | - Yuan-Yu Jau
- Sandia National Laboratories, Albuquerque, NM, United States of America
| | - Jim McKay
- Candoo Systems Inc., Coquitlam, BC, Canada
| | | | - Samu Taulu
- University of Washington Seattle, Seattle, WA, United States of America
| | - Julia M. Stephen
- The Mind Research Network and Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, United States of America
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20
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Johnson B, Jobst C, Al-Loos R, He W, Cheyne D. Individual differences in motor development during early childhood: An MEG study. Dev Sci 2020; 23:e12935. [PMID: 31869490 DOI: 10.1111/desc.12935] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 12/15/2019] [Accepted: 12/16/2019] [Indexed: 11/28/2022]
Abstract
In a previous study, we reported the first measurements of pre-movement and sensorimotor cortex activity in preschool age children (ages 3-5 years) using a customized pediatric magnetoencephalographic system. Movement-related activity in the sensorimotor cortex differed from that typically observed in adults, suggesting that maturation of cortical motor networks was still incomplete by late preschool age. Here we compare these earlier results to a group of school age children (ages 6-8 years) including seven children from the original study measured again two years later, and a group of adults (mean age 31.1 years) performing the same task. Differences in movement-related brain activity were observed both longitudinally within children in which repeated measurements were made, and cross-sectionally between preschool age children, school age children, and adults. Movement-related mu (8-12 Hz) and beta (15-30 Hz) oscillations demonstrated linear increases in amplitude and mean frequency with age. In contrast, movement-evoked gamma synchronization demonstrated a step-like transition from low (30-50 Hz) to high (70-90 Hz) narrow-band oscillations, and this occurred at different ages in different children. Notably, pre-movement activity ('readiness fields') observed in adults was absent in even the oldest children. These are the first direct observations of brain activity accompanying motor responses throughout early childhood, confirming that maturation of this activity is still incomplete by mid-childhood. In addition, individual children demonstrated markedly different developmental trajectories in movement-related brain activity, suggesting that individual differences need to be taken into account when studying motor development across age groups.
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Affiliation(s)
- Blake Johnson
- Department of Cognitive Science, Macquarie University, Sydney, NSW, Australia
| | - Cecilia Jobst
- Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Rita Al-Loos
- Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Wei He
- Department of Cognitive Science, Macquarie University, Sydney, NSW, Australia
| | - Douglas Cheyne
- Program in Neurosciences and Mental Health, Hospital for Sick Children Research Institute, Toronto, ON, Canada.,Department of Medical Imaging, University of Toronto, Toronto, ON, Canada
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21
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Yokosawa K. Overview of Magnetoencephalography—Brief History of its Sensors and Hardware. ADVANCED BIOMEDICAL ENGINEERING 2020. [DOI: 10.14326/abe.9.217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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22
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A decade of infant neuroimaging research: What have we learned and where are we going? Infant Behav Dev 2019; 58:101389. [PMID: 31778859 DOI: 10.1016/j.infbeh.2019.101389] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 10/10/2019] [Accepted: 10/10/2019] [Indexed: 12/15/2022]
Abstract
The past decade has seen the emergence of neuroimaging studies of infant populations. Incorporating imaging has resulted in invaluable insights about neurodevelopment at the start of life. However, little has been enquired of the experimental specifications and study characteristics of typical findings. This review systematically screened empirical studies that used electroencephalography (EEG), magnetoencephalography (MEG), functional near-infrared spectroscopy (fNIRS), and functional magnetic resonance imaging (fMRI) on infants (max. age of 24 months). From more than 21,000 publications, a total of 710 records were included for analyses. With the exception of EEG studies, infant studies with MEG, fNIRS, and fMRI were most often conducted around birth and at 12 months. The vast majority of infant studies came from North America, with very few studies conducted in Africa, certain parts of South America, and Southeast Asia. Finally, longitudinal neuroimaging studies were inclined to adopt EEG, followed by fMRI, fNIRS, and MEG. These results show that there is compelling need for studies with larger sample sizes, studies investigating a broader range of infant developmental periods, and studies from under- and less-developed regions in the world. Addressing these shortcomings in the future will provide a more representative and accurate understanding of neurodevelopment in infancy.
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23
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Sun L, Okada Y. Vibrotactile piezoelectric stimulation system with precise and versatile timing control for somatosensory research. J Neurosci Methods 2019; 317:29-36. [PMID: 30738105 DOI: 10.1016/j.jneumeth.2019.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 02/05/2019] [Accepted: 02/05/2019] [Indexed: 11/15/2022]
Abstract
BACKGROUND Tactile stimulations systems are useful for studying the somatosensory system in children because they are innocuous and safe. Stimulators based on piezoelectric actuator are useful, but there is still a need for such systems capable of providing accurate and versatile control of timing and pattern of activation. NEW METHOD We have implemented a vibrotactile stimulating system useful for behavioral and electroencephalography (EEG) and magnetoencephalography (MEG) research. Our design goal was to create a system capable of providing up to five independently controlled mechanical stimulations with precise timing. We developed a Graphic User Interface (GUI) in LabVIEW, which controls a commercially available piezoelectric braille stimulator using an Arduino based controller. We made a customized braille stimulator based on the Metec Braille device. RESULTS Our system can control up to five tactile stimulators with independent timing control and negligible errors. Although it can be directly used for behavioral and EEG research, the piezoelectric stimulators in our system generate stimulus artifacts that interfere with MEG recordings. A moving averaging subtraction algorithm we developed can remove the artifact. The stimulator can be used to measure somatic evoked magnetic fields from the somatosensory cortex of a child without the artifact. COMPARISON TO EXISTING METHODS Our system provides an accurate independent control of one or more piezoelectric actuators using a GUI-based easy-to-control programming approach based on recent advances in embedded systems and software. Versatility and precise stimulation timing distinguish our system compared to existing somatic stimulators. CONCLUSIONS Our system may be useful for somatic research.
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Affiliation(s)
- Limin Sun
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
| | - Yoshio Okada
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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24
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Vasung L, Abaci Turk E, Ferradal SL, Sutin J, Stout JN, Ahtam B, Lin PY, Grant PE. Exploring early human brain development with structural and physiological neuroimaging. Neuroimage 2019; 187:226-254. [PMID: 30041061 PMCID: PMC6537870 DOI: 10.1016/j.neuroimage.2018.07.041] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 07/16/2018] [Accepted: 07/16/2018] [Indexed: 12/11/2022] Open
Abstract
Early brain development, from the embryonic period to infancy, is characterized by rapid structural and functional changes. These changes can be studied using structural and physiological neuroimaging methods. In order to optimally acquire and accurately interpret this data, concepts from adult neuroimaging cannot be directly transferred. Instead, one must have a basic understanding of fetal and neonatal structural and physiological brain development, and the important modulators of this process. Here, we first review the major developmental milestones of transient cerebral structures and structural connectivity (axonal connectivity) followed by a summary of the contributions from ex vivo and in vivo MRI. Next, we discuss the basic biology of neuronal circuitry development (synaptic connectivity, i.e. ensemble of direct chemical and electrical connections between neurons), physiology of neurovascular coupling, baseline metabolic needs of the fetus and the infant, and functional connectivity (defined as statistical dependence of low-frequency spontaneous fluctuations seen with functional magnetic resonance imaging (fMRI)). The complementary roles of magnetic resonance imaging (MRI), electroencephalography (EEG), magnetoencephalography (MEG), and near-infrared spectroscopy (NIRS) are discussed. We include a section on modulators of brain development where we focus on the placenta and emerging placental MRI approaches. In each section we discuss key technical limitations of the imaging modalities and some of the limitations arising due to the biology of the system. Although neuroimaging approaches have contributed significantly to our understanding of early brain development, there is much yet to be done and a dire need for technical innovations and scientific discoveries to realize the future potential of early fetal and infant interventions to avert long term disease.
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Affiliation(s)
- Lana Vasung
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Esra Abaci Turk
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Silvina L Ferradal
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Jason Sutin
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Jeffrey N Stout
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Banu Ahtam
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Pei-Yi Lin
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - P Ellen Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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25
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Borna A, Carter TR, DeRego P, James CD, Schwindt PDD. Magnetic Source Imaging Using a Pulsed Optically Pumped Magnetometer Array. IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2019; 68:493-501. [PMID: 31777404 PMCID: PMC6880808 DOI: 10.1109/tim.2018.2851458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We have developed a pulsed optically pumped magnetometer (OPM) array for detecting magnetic field maps originated from an arbitrary current distribution. The presented magnetic source imaging (MSI) system features 24 OPM channels, has a data rate of 500 S/s, a sensitivity of 0.8 p T / H z , and a dynamic range of 72 dB. We have employed our pulsed- OPM MSI system for measuring the magnetic field map of a test coil structure. The coils are moved across the array in an indexed fashion to measure the magnetic field over an area larger than the array. The captured magnetic field maps show excellent agreement with the simulation results. Assuming a 2D current distribution, we have solved the inverse problem, using the measured magnetic field maps, and the reconstructed current distribution image is compared to that of the simulation.
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Affiliation(s)
- Amir Borna
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, USA
| | - Tony R Carter
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, USA
| | - Paul DeRego
- Kansas City National Security Campus, 2450 Alamo Ave SE, Albuquerque, NM 87106
| | - Conrad D James
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, USA
| | - Peter D D Schwindt
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, USA
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26
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Chen YH, Saby J, Kuschner E, Gaetz W, Edgar JC, Roberts TPL. Magnetoencephalography and the infant brain. Neuroimage 2019; 189:445-458. [PMID: 30685329 DOI: 10.1016/j.neuroimage.2019.01.059] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/10/2019] [Accepted: 01/22/2019] [Indexed: 12/12/2022] Open
Abstract
Magnetoencephalography (MEG) is a non-invasive neuroimaging technique that provides whole-head measures of neural activity with millisecond temporal resolution. Over the last three decades, MEG has been used for assessing brain activity, most commonly in adults. MEG has been used less often to examine neural function during early development, in large part due to the fact that infant whole-head MEG systems have only recently been developed. In this review, an overview of infant MEG studies is provided, focusing on the period from birth to three years. The advantages of MEG for measuring neural activity in infants are highlighted (See Box 1), including the ability to assess activity in brain (source) space rather than sensor space, thus allowing direct assessment of neural generator activity. Recent advances in MEG hardware and source analysis are also discussed. As the review indicates, efforts in this area demonstrate that MEG is a promising technology for studying the infant brain. As a noninvasive technology, with emerging hardware providing the necessary sensitivity, an expected deliverable is the capability for longitudinal infant MEG studies evaluating the developmental trajectory (maturation) of neural activity. It is expected that departures from neuro-typical trajectories will offer early detection and prognosis insights in infants and toddlers at-risk for neurodevelopmental disorders, thus paving the way for early targeted interventions.
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Affiliation(s)
- Yu-Han Chen
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Joni Saby
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Emily Kuschner
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - William Gaetz
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - J Christopher Edgar
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Timothy P L Roberts
- Lurie Family Foundations MEG Imaging Center, Dept. of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
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27
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Sun L, Hämäläinen MS, Okada Y. Noise cancellation for a whole-head magnetometer-based MEG system in hospital environment. Biomed Phys Eng Express 2018; 4. [PMID: 30174830 DOI: 10.1088/2057-1976/aad627] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We describe a strategy of removing magnetic field interference for a whole-head pediatric magnetoencephalography (MEG) system ("babyMEG") installed in a hospital. The 375-channel sensor array of babyMEG consists entirely of magnetometers in two layers to maximize the sensitivity for detecting MEG signals from infants, toddlers, and young children. It is equipped with a continuously operating closed-cycle helium recycler to reduce the operating costs. These two features pose special challenges for noise cancellation. Our strategy uses a combination of several methods. The system is installed in a light-weight, magnetically shielded room (MSR) equipped with an active external shielding. In addition we employ two software-based techniques - a signal space projection (SSP) technique and a synthetic gradiometer (SG) method - for removing the environmental magnetic noise in real time and displaying the output online. The shielding effects are: passive shielding - 36 dB, active shielding - 12 dB, SSP - 40 dB and SG - 40 dB, for a combined maximum shielding of about 90 dB at 0.1 Hz. We evaluated the performance of the babyMEG after applying the noise cancellation techniques. The dipole localization errors were <3 mm after averaging 50 epochs with empty room noise in a simulation study for dipoles >10 nAm, which is in the low range of empirically observed dipole moments. In a phantom study with realistic environmental noise, we could clearly recover an evoked cortical magnetic field produced by a 20 nAm dipole after averaging 50 epochs. The localization error was ~6 mm after averaging 20 epochs. In infants, we could clearly detect a somatic evoked field after averaging ~20 responses. The unique two-layer sensor design combined with the SSP or SG provides effective noise suppression for a magnetometer-based pediatric MEG system in hospital environment with the closed-cycle helium recycler operating continuously during MEG measurements.
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Affiliation(s)
- Limin Sun
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Matti S Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Massachusetts 02129, USA.,Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Yoshio Okada
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Harvard Medical School, Boston, Massachusetts 02115, USA
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Hari R, Baillet S, Barnes G, Burgess R, Forss N, Gross J, Hämäläinen M, Jensen O, Kakigi R, Mauguière F, Nakasato N, Puce A, Romani GL, Schnitzler A, Taulu S. IFCN-endorsed practical guidelines for clinical magnetoencephalography (MEG). Clin Neurophysiol 2018; 129:1720-1747. [PMID: 29724661 PMCID: PMC6045462 DOI: 10.1016/j.clinph.2018.03.042] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 03/18/2018] [Accepted: 03/24/2018] [Indexed: 12/22/2022]
Abstract
Magnetoencephalography (MEG) records weak magnetic fields outside the human head and thereby provides millisecond-accurate information about neuronal currents supporting human brain function. MEG and electroencephalography (EEG) are closely related complementary methods and should be interpreted together whenever possible. This manuscript covers the basic physical and physiological principles of MEG and discusses the main aspects of state-of-the-art MEG data analysis. We provide guidelines for best practices of patient preparation, stimulus presentation, MEG data collection and analysis, as well as for MEG interpretation in routine clinical examinations. In 2017, about 200 whole-scalp MEG devices were in operation worldwide, many of them located in clinical environments. Yet, the established clinical indications for MEG examinations remain few, mainly restricted to the diagnostics of epilepsy and to preoperative functional evaluation of neurosurgical patients. We are confident that the extensive ongoing basic MEG research indicates potential for the evaluation of neurological and psychiatric syndromes, developmental disorders, and the integrity of cortical brain networks after stroke. Basic and clinical research is, thus, paving way for new clinical applications to be identified by an increasing number of practitioners of MEG.
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Affiliation(s)
- Riitta Hari
- Department of Art, Aalto University, Helsinki, Finland.
| | - Sylvain Baillet
- McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Gareth Barnes
- Wellcome Centre for Human Neuroimaging, University College of London, London, UK
| | - Richard Burgess
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Nina Forss
- Clinical Neuroscience, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Joachim Gross
- Centre for Cognitive Neuroimaging, University of Glasgow, Glasgow, UK; Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Germany
| | - Matti Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Harvard Medical School, Boston, MA, USA; NatMEG, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ole Jensen
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Ryusuke Kakigi
- Department of Integrative Physiology, National Institute of Physiological Sciences, Okazaki, Japan
| | - François Mauguière
- Department of Functional Neurology and Epileptology, Neurological Hospital & University of Lyon, Lyon, France
| | | | - Aina Puce
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Gian-Luca Romani
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. D'Annunzio, Chieti, Italy
| | - Alfons Schnitzler
- Institute of Clinical Neuroscience and Medical Psychology, and Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Samu Taulu
- Institute for Learning & Brain Sciences, University of Washington, Seattle, WA, USA; Department of Physics, University of Washington, Seattle, WA, USA
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Esch L, Sun L, Klüber V, Lew S, Baumgarten D, Grant PE, Okada Y, Haueisen J, Hämäläinen MS, Dinh C. MNE Scan: Software for real-time processing of electrophysiological data. J Neurosci Methods 2018; 303:55-67. [PMID: 29621570 PMCID: PMC5940556 DOI: 10.1016/j.jneumeth.2018.03.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 03/31/2018] [Accepted: 03/31/2018] [Indexed: 12/29/2022]
Abstract
BACKGROUND Magnetoencephalography (MEG) and Electroencephalography (EEG) are noninvasive techniques to study the electrophysiological activity of the human brain. Thus, they are well suited for real-time monitoring and analysis of neuronal activity. Real-time MEG/EEG data processing allows adjustment of the stimuli to the subject's responses for optimizing the acquired information especially by providing dynamically changing displays to enable neurofeedback. NEW METHOD We introduce MNE Scan, an acquisition and real-time analysis software based on the multipurpose software library MNE-CPP. MNE Scan allows the development and application of acquisition and novel real-time processing methods in both research and clinical studies. The MNE Scan development follows a strict software engineering process to enable approvals required for clinical software. RESULTS We tested the performance of MNE Scan in several device-independent use cases, including, a clinical epilepsy study, real-time source estimation, and Brain Computer Interface (BCI) application. COMPARISON WITH EXISTING METHOD(S) Compared to existing tools we propose a modular software considering clinical software requirements expected by certification authorities. At the same time the software is extendable and freely accessible. CONCLUSION We conclude that MNE Scan is the first step in creating a device-independent open-source software to facilitate the transition from basic neuroscience research to both applied sciences and clinical applications.
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Affiliation(s)
- Lorenz Esch
- Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA; Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA; Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff- Str. 2, 98693 Ilmenau, Germany.
| | - Limin Sun
- Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA; Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Viktor Klüber
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff- Str. 2, 98693 Ilmenau, Germany; Institute of Nuclear and Energy Technologies, KIT - Karlsruher Institut für Technologie, 76344 Eggenstein-Leopoldshafen, Germany
| | - Seok Lew
- Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA; Department of Engineering, Olivet Nazarene University, 1 University Ave, Bourbonnais, 60914 IL, USA
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT - University of Health Sciences, Medical Informatics and Technology, 6060 Hall in Tirol, Austria
| | - P Ellen Grant
- Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA; Boston Children's Hospital, Division of Neuroradiology, Department of Radiology, Harvard Medical School, Boston, MA 02115 USA
| | - Yoshio Okada
- Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Jens Haueisen
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff- Str. 2, 98693 Ilmenau, Germany; Biomagnetic Center, Clinic for Neurology, Jena University Hospital, Erlanger Allee 101, 07743 Jena, Germany
| | - Matti S Hämäläinen
- Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA; Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
| | - Christoph Dinh
- Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA; Boston Children's Hospital, Division of Newborn Medicine, Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
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Borna A, Carter TR, Goldberg JD, Colombo AP, Jau YY, Berry C, McKay J, Stephen J, Weisend M, Schwindt PDD. A 20-channel magnetoencephalography system based on optically pumped magnetometers. Phys Med Biol 2017; 62:8909-8923. [PMID: 29035875 DOI: 10.1088/1361-6560/aa93d1] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We describe a multichannel magnetoencephalography (MEG) system that uses optically pumped magnetometers (OPMs) to sense the magnetic fields of the human brain. The system consists of an array of 20 OPM channels conforming to the human subject's head, a person-sized magnetic shield containing the array and the human subject, a laser system to drive the OPM array, and various control and data acquisition systems. We conducted two MEG experiments: auditory evoked magnetic field and somatosensory evoked magnetic field, on three healthy male subjects, using both our OPM array and a 306-channel Elekta-Neuromag superconducting quantum interference device (SQUID) MEG system. The described OPM array measures the tangential components of the magnetic field as opposed to the radial component measured by most SQUID-based MEG systems. Herein, we compare the results of the OPM- and SQUID-based MEG systems on the auditory and somatosensory data recorded in the same individuals on both systems.
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Affiliation(s)
- Amir Borna
- Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1082, United States of America
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Ouyang M, Kang H, Detre JA, Roberts TPL, Huang H. Short-range connections in the developmental connectome during typical and atypical brain maturation. Neurosci Biobehav Rev 2017; 83:109-122. [PMID: 29024679 DOI: 10.1016/j.neubiorev.2017.10.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 09/09/2017] [Accepted: 10/06/2017] [Indexed: 01/10/2023]
Abstract
The human brain is remarkably complex with connectivity constituting its basic organizing principle. Although long-range connectivity has been focused on in most research, short-range connectivity is characterized by unique and spatiotemporally heterogeneous dynamics from infancy to adulthood. Alterations in the maturational dynamics of short-range connectivity has been associated with neuropsychiatric disorders, such as autism and schizophrenia. Recent advances in neuroimaging techniques, especially diffusion magnetic resonance imaging (dMRI), resting-state functional MRI (rs-fMRI), electroencephalography (EEG) and magnetoencephalography (MEG), have made quantification of short-range connectivity possible in pediatric populations. This review summarizes findings on the development of short-range functional and structural connections at the macroscale. These findings suggest an inverted U-shaped pattern of maturation from primary to higher-order brain regions, and possible "hyper-" and "hypo-" short-range connections in autism and schizophrenia, respectively. The precisely balanced short- and long-range connections contribute to the integration and segregation of the connectome during development. The mechanistic relationship among short-range connectivity maturation, the developmental connectome and emerging brain functions needs further investigation, including the refinement of methodological approaches.
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Affiliation(s)
- Minhui Ouyang
- Radiology Research, Children's Hospital of Philadelphia, PA, United States
| | - Huiying Kang
- Radiology Research, Children's Hospital of Philadelphia, PA, United States; Department of Radiology, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - John A Detre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, PA, United States; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, United States
| | - Timothy P L Roberts
- Radiology Research, Children's Hospital of Philadelphia, PA, United States; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, United States
| | - Hao Huang
- Radiology Research, Children's Hospital of Philadelphia, PA, United States; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, United States.
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Toward noninvasive monitoring of ongoing electrical activity of human uterus and fetal heart and brain. Clin Neurophysiol 2017; 128:2470-2481. [PMID: 29100065 PMCID: PMC5697525 DOI: 10.1016/j.clinph.2017.08.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 08/01/2017] [Accepted: 08/12/2017] [Indexed: 11/23/2022]
Abstract
Evaluated a fetal-maternal scanner for monitoring electrical maternal and fetal organ activity. The simulated scanner can monitor the uterine and fetal heart and brain activity online. Biomagnetic monitors similar to this instrument should be useful in clinical neurophysiology.
Objective To evaluate whether a full-coverage fetal-maternal scanner can noninvasively monitor ongoing electrophysiological activity of maternal and fetal organs. Methods A simulation study was carried out for a scanner with an array of magnetic field sensors placed all around the torso from the chest to the hip within a horizontal magnetic shielding enclosure. The magnetic fields from internal organs and an external noise source were computed for a pregnant woman with a 35-week old fetus. Signal processing methods were used to reject the external and internal interferences, to visualize uterine activity, and to detect activity of fetal heart and brain. Results External interference was reduced by a factor of 1000, sufficient for detecting signals from internal organs when combined with passive and active shielding. The scanner rejects internal interferences better than partial-coverage arrays. It can be used to estimate currents around the uterus. It clearly detects spontaneous activity from the fetal heart and brain without averaging and weaker evoked brain activity at all fetal head positions after averaging. Conclusion The simulated device will be able to monitor the ongoing activity of the fetal and maternal organs. Significance This type of scanner may become a novel tool in fetal medicine.
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Sun L, Han M, Pratt K, Paulson D, Dinh C, Esch L, Okada Y, Hämäläinen M. Versatile synchronized real-time MEG hardware controller for large-scale fast data acquisition. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:055110. [PMID: 28571426 DOI: 10.1063/1.4983080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Versatile controllers for accurate, fast, and real-time synchronized acquisition of large-scale data are useful in many areas of science, engineering, and technology. Here, we describe the development of a controller software based on a technique called queued state machine for controlling the data acquisition (DAQ) hardware, continuously acquiring a large amount of data synchronized across a large number of channels (>400) at a fast rate (up to 20 kHz/channel) in real time, and interfacing with applications for real-time data analysis and display of electrophysiological data. This DAQ controller was developed specifically for a 384-channel pediatric whole-head magnetoencephalography (MEG) system, but its architecture is useful for wide applications. This controller running in a LabVIEW environment interfaces with microprocessors in the MEG sensor electronics to control their real-time operation. It also interfaces with a real-time MEG analysis software via transmission control protocol/internet protocol, to control the synchronous acquisition and transfer of the data in real time from >400 channels to acquisition and analysis workstations. The successful implementation of this controller for an MEG system with a large number of channels demonstrates the feasibility of employing the present architecture in several other applications.
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Affiliation(s)
- Limin Sun
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Menglai Han
- Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA
| | - Kevin Pratt
- Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA
| | - Douglas Paulson
- Tristan Technologies, Inc., 6191 Cornerstone Court East, Suite 107, San Diego, California 92121, USA
| | - Christoph Dinh
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 2, 98693, Ilmenau, Germany
| | - Lorenz Esch
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Gustav-Kirchhoff-Str. 2, 98693, Ilmenau, Germany
| | - Yoshio Okada
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Matti Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA
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Magnetoencephalography for brain electrophysiology and imaging. Nat Neurosci 2017; 20:327-339. [DOI: 10.1038/nn.4504] [Citation(s) in RCA: 418] [Impact Index Per Article: 59.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/17/2017] [Indexed: 12/18/2022]
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