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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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Magnetotrichography: Measuring the dc magnetic field produced by hair follicles. Sci Rep 2019; 9:15624. [PMID: 31666670 PMCID: PMC6821812 DOI: 10.1038/s41598-019-52110-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 10/02/2019] [Indexed: 11/28/2022] Open
Abstract
We here describe the dc magnetic field over the human head produced by healthy hair follicles when the scalp is lightly pressed. This phenomenon was briefly reported decades earlier, where a double-planar SQUID (Superconducting Quantum Interference Devices) gradiometer at a single location was used. We here perform a larger study, using the dcMEG containing 102 double-planar gradiometers covering the whole scalp. The field is displayed as an on-line arrow map over the head, showing the approximate flow of direct current (dc) in the scalp. Standard sets of five arrow maps per subject were measured, where the subject successively pressed parts of their head against the inside of the helmet. These maps were made for 15 normal subjects (5 females), and 2 with alopecia (non-functioning follicles). The directions of “pressed” generating arrows always followed the natural tilt of the follicles, verifying the follicles as generators, with a time constant of about one second. The maximum generator dipole strength was about 24 µA-cm. Scalp electric potentials corresponding to the magnetic signals were masked by much larger electrodermal potentials. Therefore, this magnetic method, called magnetotrichography, is unique in measuring this follicular electrical activity, with possible applications in studying baldness and hair diseases.
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Carrette E, Stefan H. Evidence for the Role of Magnetic Source Imaging in the Presurgical Evaluation of Refractory Epilepsy Patients. Front Neurol 2019; 10:933. [PMID: 31551904 PMCID: PMC6746885 DOI: 10.3389/fneur.2019.00933] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/12/2019] [Indexed: 12/03/2022] Open
Abstract
Magnetoencephalography (MEG) in the field of epilepsy has multiple advantages; just like electroencephalography (EEG), MEG is able to measure the epilepsy specific information (i.e., the brain activity reflecting seizures and/or interictal epileptiform discharges) directly, non-invasively and with a very high temporal resolution (millisecond-range). In addition MEG has a unique sensitivity for tangential sources, resulting in a full picture of the brain activity when combined with EEG. It accurately allows to perform source imaging of focal epileptic activity and functional cortex and shows a specific high sensitivity for a source in the neocortex. In this paper the current evidence and practice for using magnetic source imaging of focal interictal and ictal epileptic activity during the presurgical evaluation of drug resistant patients is being reviewed.
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Affiliation(s)
- Evelien Carrette
- Reference Centre for Refractory Epilepsy, Ghent University Hospital, Ghent, Belgium
| | - Hermann Stefan
- Department of Neurology-Biomagnetism, University Hospital Erlangen, Erlangen, Germany
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Khan S, Cohen D. Using the magnetoencephalogram to noninvasively measure magnetite in the living human brain. Hum Brain Mapp 2018; 40:1654-1665. [PMID: 30457688 PMCID: PMC6587731 DOI: 10.1002/hbm.24477] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/04/2018] [Accepted: 11/06/2018] [Indexed: 12/03/2022] Open
Abstract
During the past several decades there has been much interest in the existence of magnetite particles in the human brain and their accumulation with age. These particles also appear to play an important role in neurodegenerative diseases of the brain. However, up to now the amount and distribution of these particles has been measured only in post‐mortem brain tissue. Although in‐vivo MRI measurements do show iron compounds generally, MRI cannot separate them according to their magnetic phases, which are associated with their chemical interactions. In contrast, we here offer a new noninvasive, in‐vivo method which is selectively sensitive only to particles which can be strongly magnetized. We magnetize these particles with a strong magnetic field through the head, and then measure the resulting magnetic fields, using the dcMagnetoencephalogram (dcMEG). From these data, the mass and locations of the particles can be estimated, using a distributed inverse solution. To test the method, we measured 11 healthy male subjects (ages 19–89 year). Accumulation of magnetite, in the hippocampal formation or nearby structures, was observed in the older men. These in‐vivo findings agree with reports of post‐mortem measurements of their locations, and of their accumulation with age. Thus, our findings allow in‐vivo measurement of magnetite in the human brain, and possibly open the door for new studies of neurodegenerative diseases of the brain.
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Affiliation(s)
- Sheraz Khan
- Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts
| | - David Cohen
- Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.,Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts.,Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts
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Bastany ZJ, Askari S, Dumont GA, Speckmann EJ, Gorji A. Non-invasive monitoring of spreading depression. Neuroscience 2016; 333:1-12. [DOI: 10.1016/j.neuroscience.2016.06.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/30/2016] [Accepted: 06/30/2016] [Indexed: 10/21/2022]
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Leiken KA, Xiang J, Curry E, Fujiwara H, Rose DF, Allen JR, Kacperski JE, O'Brien HL, Kabbouche MA, Powers SW, Hershey AD. Quantitative neuromagnetic signatures of aberrant cortical excitability in pediatric chronic migraine. J Headache Pain 2016; 17:46. [PMID: 27113076 PMCID: PMC4844586 DOI: 10.1186/s10194-016-0641-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/15/2016] [Indexed: 11/24/2022] Open
Abstract
Background Reports have suggested that abnormal cortical excitability may be associated with acute migraines. The present study quantitatively assesses the degree of cortical excitability in chronic migraine as compared to acute migraine and healthy controls within the pediatric population. Methods We investigated 27 children suffering from chronic migraine, 27 children suffering from acute migraine, and 27 healthy controls using a magnetoencephalography (MEG) system, recording at a sampling rate of 6000 Hz. All groups were age-matched and gender-matched. Neuromagnetic brain activation was elicited by a finger-tapping motor task. The spatiotemporal and spectral signatures of MEG data within a 5–2884 Hz range were analyzed using Morlet wavelet transform and beamformer analyses. Results Compared with controls, the chronic migraine group showed (1) significantly prolonged latencies of movement-elicited magnetic fields (MEFs) between 5 and 100 Hz; (2) increased spectral power between 100 and 200 Hz, and between 2200 and 2800 Hz; and (3) a higher likelihood of neuromagnetic activation in the ipsilateral sensorimotor cortices, supplementary motor area, and occipital regions. Compared with acute migraine group, chronic migraine patients showed (1) significantly higher odds of having strong MEFs after 150 ms; and (2) significantly higher odds of having neuromagnetic activation from the deep brain areas. Conclusions Results demonstrated that chronic migraine subjects were not only different from the healthy controls, but also different from acute migraine subjects. The chronification of migraines may be associated with elevated cortical excitability, delayed and spread neural response, as well as aberrant activation from deep brain areas.
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Affiliation(s)
- Kimberly A Leiken
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.
| | - Jing Xiang
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Emily Curry
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA
| | - Hisako Fujiwara
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA
| | - Douglas F Rose
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Janelle R Allen
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Joanne E Kacperski
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Hope L O'Brien
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Marielle A Kabbouche
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
| | - Scott W Powers
- Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA.,Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Andrew D Hershey
- Division of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 2015, Cincinnati, OH, 45220, USA.,Department of Pediatrics, University of Cincinnati, College of Medicine, Cincinnati, OH, USA
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Leiken K, Xiang J, Zhang F, Shi J, Tang L, Liu H, Wang X. Magnetoencephalography detection of high-frequency oscillations in the developing brain. Front Hum Neurosci 2014; 8:969. [PMID: 25566015 PMCID: PMC4264504 DOI: 10.3389/fnhum.2014.00969] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/13/2014] [Indexed: 11/13/2022] Open
Abstract
Increasing evidence from invasive intracranial recordings suggests that the matured brain generates both physiological and pathological high-frequency signals. The present study was designed to detect high-frequency brain signals in the developing brain using newly developed magnetoencephalography (MEG) methods. Twenty healthy children were studied with a high-sampling rate MEG system. Functional high-frequency brain signals were evoked by electrical stimulation applied to the index fingers. To determine if the high-frequency neuromagnetic signals are true brain responses in high-frequency range, we analyzed the MEG data using the conventional averaging as well as newly developed time-frequency analysis along with beamforming. The data of healthy children showed that very high-frequency brain signals (>1000 Hz) in the somatosensory cortex in the developing brain could be detected and localized using MEG. The amplitude of very high-frequency brain signals was significantly weaker than that of the low-frequency brain signals. Very high-frequency brain signals showed a much earlier latency than those of a low-frequency. Magnetic source imaging (MSI) revealed that a portion of the high-frequency signals was from the somatosensory cortex, another portion of the high-frequency signals was probably from the thalamus. Our results provide evidence that the developing brain generates high-frequency signals that can be detected with the non-invasive technique of MEG. MEG detection of high-frequency brain signals may open a new window for the study of developing brain function.
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Affiliation(s)
- Kimberly Leiken
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA
| | - Jing Xiang
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA
| | - Fawen Zhang
- Department of Communication Sciences and Disorders, University of Cincinnati , Cincinnati, OH , USA
| | - Jingping Shi
- Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Lu Tang
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Hongxing Liu
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Xiaoshan Wang
- Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
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Xiang J, Korman A, Samarasinghe KM, Wang X, Zhang F, Qiao H, Sun B, Wang F, Fan HH, Thompson EA. Volumetric imaging of brain activity with spatial-frequency decoding of neuromagnetic signals. J Neurosci Methods 2014; 239:114-28. [PMID: 25455340 DOI: 10.1016/j.jneumeth.2014.10.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 10/07/2014] [Accepted: 10/09/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND The brain generates signals in a wide frequency range (∼2840 Hz). Existing magnetoencephalography (MEG) methods typically detect brain activity in a median-frequency range (1-70 Hz). The objective of the present study was to develop a new method to utilize the frequency signatures for source imaging. NEW METHOD Morlet wavelet transform and two-step beamforming were integrated into a systematic approach to estimate magnetic sources in time-frequency domains. A grid-frequency kernel (GFK) was developed to decode the correlation between each time-frequency representation and grid voxel. Brain activity was reconstructed by accumulating spatial- and frequency-locked signals in the full spectral data for all grid voxels. To test the new method, MEG data were recorded from 20 healthy subjects and 3 patients with verified epileptic foci. RESULTS The experimental results showed that the new method could accurately localize brain activation in auditory cortices. The epileptic foci localized with the new method were spatially concordant with invasive recordings. COMPARISON WITH EXISTING METHODS Compared with well-known existing methods, the new method is objective because it scans the entire brain without making any assumption about the number of sources. The novel feature of the new method is its ability to localize high-frequency sources. CONCLUSIONS The new method could accurately localize both low- and high-frequency brain activities. The detection of high-frequency MEG signals can open a new avenue in the study of the human brain function as well as a variety of brain disorders.
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Affiliation(s)
- Jing Xiang
- MEG Center, Department of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, USA.
| | - Abraham Korman
- MEG Center, Department of Neurology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, USA
| | - Kasun M Samarasinghe
- Department of Electrical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Xiaopei Wang
- Department of Mathematical Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Fawen Zhang
- Department of Communication Sciences and Disorders, University of Cincinnati, OH, USA
| | - Hui Qiao
- MEG Laboratory, Beijing Tiantan Hospital, Beijing, People's Republic of China
| | - Bo Sun
- MEG Laboratory, Beijing Tiantan Hospital, Beijing, People's Republic of China
| | - Fengbin Wang
- MEG Laboratory, Beijing Tiantan Hospital, Beijing, People's Republic of China
| | - Howard H Fan
- Department of Electrical Engineering, University of Cincinnati, Cincinnati, OH, USA
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