A new approach to neuroimaging with magnetoencephalography

We discuss the application of beamforming techniques to the field of magnetoencephalography (MEG). We argue that beamformers have given us an insight into the dynamics of oscillatory changes across the cortex not explored previously with traditional analysis techniques that rely on averaged evoked responses. We review several experiments that have used beamformers, with special emphasis on those in which the results have been compared to those observed in functional magnetic resonance imaging (fMRI) and on those studying induced phenomena. We suggest that the success of the beamformer technique, despite the assumption that there are no linear interactions between the mesoscopic local field potentials across distinct cortical areas, may tell us something of the balance between functional integration and segregation in the human brain. What is more, MEG beamformer analysis facilitates the study of these complex interactions within cortical networks that are involved in both sensory‐motor and cognitive processes. Hum. Brain Mapp 25:199–211, 2005. © 2005 Wiley‐Liss, Inc.

[1]  H. Schimmel.  The (�) Reference: Accuracy of Estimated Mean Components in Average Response Studies , 1967, Science.

[2]  Mardi J. Horowitz,et al.  States of Mind , 1979, Critical Issues in Psychiatry.

[3]  L. Kaufman,et al.  Modulation transfer functions of the human visual system revealed by magnetic field measurements , 1982, Vision Research.

[4]  M. Singh,et al.  Reconstruction of Images from Neuromagnetic Fields , 1984, IEEE Transactions on Nuclear Science.

[5]  R. Ilmoniemi,et al.  Selective localization of alpha brain activity with neuromagnetic measurements. , 1984, Electroencephalography and clinical neurophysiology.

[6]  M. Scherg,et al.  Two bilateral sources of the late AEP as identified by a spatio-temporal dipole model. , 1985, Electroencephalography and clinical neurophysiology.

[7]  M. Scherg,et al.  Evoked dipole source potentials of the human auditory cortex. , 1986, Electroencephalography and clinical neurophysiology.

[8]  D K Prasher,et al.  Latency variability and temporal interrelationships of the auditory event-related potentials (N1, P2, N2, and P3) in normal subjects. , 1986, Electroencephalography and clinical neurophysiology.

[9]  B.D. Van Veen,et al.  Beamforming: a versatile approach to spatial filtering , 1988, IEEE ASSP Magazine.

[10]  Karl J. Friston,et al.  The colour centre in the cerebral cortex of man , 1989, Nature.

[11]  Karl J. Friston,et al.  The Relationship between Global and Local Changes in PET Scans , 1990, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[12]  Karl J. Friston,et al.  Comparing Functional (PET) Images: The Assessment of Significant Change , 1991, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[13]  A Z Snyder,et al.  Dipole source localization in the study of EP generators: a critique. , 1991, Electroencephalography and clinical neurophysiology.

[14]  J.C. Mosher,et al.  Multiple dipole modeling and localization from spatio-temporal MEG data , 1992, IEEE Transactions on Biomedical Engineering.

[15]  S. Supek,et al.  Simulation studies of multiple dipole neuromagnetic source localization: model order and limits of source resolution , 1993, IEEE Transactions on Biomedical Engineering.

[16]  D. Lehmann,et al.  Low resolution electromagnetic tomography: a new method for localizing electrical activity in the brain. , 1994, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[17]  Karl J. Friston,et al.  Statistical parametric maps in functional imaging: A general linear approach , 1994 .

[18]  L. C. Liu,et al.  Magnetic field tomography of cortical and deep processes: examples of "real-time mapping" of averaged and single trial MEG signals. , 1995, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[19]  A. Opstal.  Dynamic Patterns: The Self-Organization of Brain and Behavior , 1995 .

[20]  S Micheloyannis,et al.  Generators for human P300 elicited by somatosensory stimuli using multiple dipole source analysis , 1996, Neuroscience.

[21]  A. Grinvald,et al.  Dynamics of Ongoing Activity: Explanation of the Large Variability in Evoked Cortical Responses , 1996, Science.

[22]  Gavan Lintern,et al.  Dynamic patterns: The self-organization of brain and behavior , 1997, Complex.

[23]  W. Drongelen,et al.  Localization of brain electrical activity via linearly constrained minimum variance spatial filtering , 1997, IEEE Transactions on Biomedical Engineering.

[24]  Sylvain Baillet,et al.  A Bayesian approach to introducing anatomo-functional priors in the EEG/MEG inverse problem , 1997, IEEE Transactions on Biomedical Engineering.

[25]  N Forss,et al.  Effects of stimulus intensity on signals from human somatosensory cortices , 1998, Neuroreport.

[26]  W Singer,et al.  Consciousness and the structure of neuronal representations. , 1998, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[27]  G. Edelman,et al.  Consciousness and Complexity , 1998 .

[28]  J Vieth,et al.  Responses to silent Kanji reading of the native Japanese and German in task subtraction magnetoencephalography. , 1998, Brain research. Cognitive brain research.

[29]  R. Llinás,et al.  The neuronal basis for consciousness. , 1998, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[30]  F. L. D. Silva,et al.  Event-related EEG/MEG synchronization and desynchronization: basic principles , 1999, Clinical Neurophysiology.

[31]  T. Inouye,et al.  Medial prefrontal cortex generates frontal midline theta rhythm. , 1999, Neuroreport.

[32]  T Imada,et al.  Dynamic cortical activation in mental image processing revealed by biomagnetic measurement. , 1999, Neuroreport.

[33]  S. Yoshizawa,et al.  A new method for magnetoencephalography: a three-dimensional magnetometer-spatial filter system , 1999, Neuroscience.

[34]  G. Berns.  Functional neuroimaging. , 1999, Life sciences.

[35]  Se Robinson,et al.  Functional neuroimaging by Synthetic Aperture Magnetometry (SAM) , 1999 .

[36]  Olaf Sporns,et al.  Connectivity and complexity: the relationship between neuroanatomy and brain dynamics , 2000, Neural Networks.

[37]  C Pantev,et al.  Magnetic brain activity evoked and induced by visually presented words and nonverbal stimuli. , 2000, Psychophysiology.

[38]  E. Halgren,et al.  Dynamic Statistical Parametric Mapping Combining fMRI and MEG for High-Resolution Imaging of Cortical Activity , 2000, Neuron.

[39]  D. Poeppel,et al.  Latency of the auditory evoked neuromagnetic field components: stimulus dependence and insights toward perception. , 2000, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[40]  Norihiko Fujita,et al.  Movement-Related Desynchronization of the Cerebral Cortex Studied with Spatially Filtered Magnetoencephalography , 2000, NeuroImage.

[41]  R. Cabeza,et al.  Imaging Cognition II: An Empirical Review of 275 PET and fMRI Studies , 2000, Journal of Cognitive Neuroscience.

[42]  Karl J. Friston,et al.  Variability in fMRI: An Examination of Intersession Differences , 2000, NeuroImage.

[43]  J. Xiong,et al.  Intersubject Variability in Cortical Activations during a Complex Language Task , 2000, NeuroImage.

[44]  E Başar,et al.  A new strategy involving multiple cognitive paradigms demonstrates that ERP components are determined by the superposition of oscillatory responses , 2000, Clinical Neurophysiology.

[45]  Karl J. Friston.  The labile brain. I. Neuronal transients and nonlinear coupling. , 2000, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[46]  R. Hari,et al.  Timing of human cortical functions during cognition: role of MEG , 2000, Trends in Cognitive Sciences.

[47]  A. Ioannides.  Real Time Human Brain Function: Observations and Inferences from Single Trial Analysis of Magnetoencephalographic Signals , 2001, Clinical EEG.

[48]  A. Schnitzler,et al.  Dynamic imaging of coherent sources: Studying neural interactions in the human brain. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[49]  K Sekihara,et al.  Dynamic activation of distinct cytoarchitectonic areas of the human SI cortex after median nerve stimulation , 2001, Neuroreport.

[50]  K Sekihara,et al.  Serial activation of distinct cytoarchitectonic areas of the human S1 cortex after posterior tibial nerve stimulation , 2001, Neuroreport.

[51]  J. Kelso,et al.  Cortical coordination dynamics and cognition , 2001, Trends in Cognitive Sciences.

[52]  W. Singer,et al.  Dynamic predictions: Oscillations and synchrony in top–down processing , 2001, Nature Reviews Neuroscience.

[53]  E. Basar,et al.  Gamma, alpha, delta, and theta oscillations govern cognitive processes. , 2001, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

[54]  David Poeppel,et al.  Reconstructing spatio-temporal activities of neural sources using an MEG vector beamformer technique , 2001, IEEE Transactions on Biomedical Engineering.

[55]  S. Morand,et al.  Electric source imaging of human brain functions , 2001, Brain Research Reviews.

[56]  N. Logothetis,et al.  Neurophysiological investigation of the basis of the fMRI signal , 2001, Nature.

[57]  G. Pfurtscheller,et al.  Evidence for distinct beta resonance frequencies in human EEG related to specific sensorimotor cortical areas , 2001, Clinical Neurophysiology.

[58]  Functional neuroimaging of cognition: state-of-the-art. , 2001, Scandinavian journal of psychology.

[59]  E Stern,et al.  Advances in Functional Neuroimaging Methodology for the Study of Brain Systems Underlying Human Neuropsychological Function and Dysfunction , 2001, Journal of clinical and experimental neuropsychology.

[60]  J. Vrba,et al.  Signal processing in magnetoencephalography. , 2001, Methods.

[61]  J Vieth,et al.  New approach to localize speech relevant brain areas and hemispheric dominance using spatially filtered magnetoencephalography , 2001, Human brain mapping.

[62]  H. Otsubo,et al.  Neuromagnetic spectral distribution of implicit processing of words , 2001, Neuroreport.

[63]  Richard M. Leahy,et al.  Electromagnetic brain mapping , 2001, IEEE Signal Process. Mag..

[64]  Joachim Gross,et al.  Cortical representation of first and second pain sensation in humans , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[65]  Olivier David,et al.  Estimation of neural dynamics from MEG/EEG cortical current density maps: application to the reconstruction of large-scale cortical synchrony , 2002, IEEE Transactions on Biomedical Engineering.

[66]  R. Leahy,et al.  On MEG forward modelling using multipolar expansions. , 2002, Physics in medicine and biology.

[67]  Hae-Jeong Park,et al.  Statistical parametric mapping of LORETA using high density EEG and individual MRI: Application to mismatch negativities in Schizophrenia , 2002, Human brain mapping.

[68]  Claudio Babiloni,et al.  Comparison between SI and SII responses as a function of stimulus intensity , 2002, Neuroreport.

[69]  Adrian L. Williams,et al.  Task-Related Changes in Cortical Synchronization Are Spatially Coincident with the Hemodynamic Response , 2002, NeuroImage.

[70]  T. Sejnowski,et al.  Dynamic Brain Sources of Visual Evoked Responses , 2002, Science.

[71]  Christo Pantev,et al.  MEG study of long-term cortical reorganization of sensorimotor areas with respect to using chopsticks , 2002, Neuroreport.

[72]  Scott T. Grafton,et al.  Extensive Individual Differences in Brain Activations Associated with Episodic Retrieval are Reliable Over Time , 2002, Journal of Cognitive Neuroscience.

[73]  J. Vrba.  Magnetoencephalography: the art of finding a needle in a haystack , 2002 .

[74]  Toshiki Yoshimine,et al.  Frequency-dependent spatial distribution of human somatosensory evoked neuromagnetic fields , 2002, Neuroscience Letters.

[75]  G Pfurtscheller,et al.  Visualization of significant ERD/ERS patterns in multichannel EEG and ECoG data , 2002, Clinical Neurophysiology.

[76]  Anders M. Dale,et al.  N400-like Magnetoencephalography Responses Modulated by Semantic Context, Word Frequency, and Lexical Class in Sentences , 2002, NeuroImage.

[77]  David Poeppel,et al.  Application of an MEG eigenspace beamformer to reconstructing spatio‐temporal activities of neural sources , 2002, Human brain mapping.

[78]  Ryouhei Ishii,et al.  Parallel distributed processing neuroimaging in the Stroop task using spatially filtered magnetoencephalography analysis , 2002, Neuroscience Letters.

[79]  Henry Markram,et al.  Real-Time Computing Without Stable States: A New Framework for Neural Computation Based on Perturbations , 2002, Neural Computation.

[80]  Thomas E. Nichols,et al.  Nonparametric permutation tests for functional neuroimaging: A primer with examples , 2002, Human brain mapping.

[81]  Wilkin Chau,et al.  Current source density distribution of sleep spindles in humans as found by synthetic aperture magnetometry , 2003, Neuroscience Letters.

[82]  Dario L. Ringach,et al.  States of mind , 2003, Nature.

[83]  F. Varela,et al.  Neuromagnetic imaging of cortical oscillations accompanying tactile stimulation. , 2003, Brain research. Cognitive brain research.

[84]  G. Barnes,et al.  Statistical flattening of MEG beamformer images , 2003, Human brain mapping.

[85]  Toshiki Yoshimine,et al.  Neuromagnetic gamma-band activity in the primary and secondary somatosensory areas , 2003, Neuroreport.

[86]  L. Pylkkänen,et al.  Tracking the time course of word recognition with MEG , 2003, Trends in Cognitive Sciences.

[87]  D. Cheyne,et al.  Localization of human somatosensory cortex using spatially filtered magnetoencephalography , 2003, Neuroscience Letters.

[88]  H. Semlitsch,et al.  Non-invasive localization of P300 sources in normal aging and age-associated memory impairment , 2003, Neurobiology of Aging.

[89]  R. Leahy,et al.  Equivalence of linear approaches in bioelectromagnetic inverse solutions , 2004, IEEE Workshop on Statistical Signal Processing, 2003.

[90]  Daniel Gounot,et al.  The BOLD response and the gamma oscillations respond differently than evoked potentials: an interleaved EEG-fMRI study , 2003, BMC Neuroscience.

[91]  Gareth R. Barnes,et al.  The use of anatomical constraints with MEG beamformers , 2003, NeuroImage.

[92]  J Gross,et al.  Properties of MEG tomographic maps obtained with spatial filtering , 2003, NeuroImage.

[93]  Wilkin Chau,et al.  Determination of activation areas in the human auditory cortex by means of synthetic aperture magnetometry , 2003, NeuroImage.

[94]  Hiroshi Otsubo,et al.  Volumetric localization of somatosensory cortex in children using synthetic aperture magnetometry , 2003, Pediatric Radiology.

[95]  R Ishii,et al.  Neuroimaging evidence for cortical involvement in the preparation and in the act of swallowing , 2003, NeuroImage.

[96]  Gareth R. Barnes,et al.  Group imaging of task-related changes in cortical synchronisation using nonparametric permutation testing , 2003, NeuroImage.

[97]  A. Grinvald,et al.  Spontaneously emerging cortical representations of visual attributes , 2003, Nature.

[98]  G. Barnes,et al.  Realistic spatial sampling for MEG beamformer images , 2004, Human brain mapping.

[99]  M-X Huang,et al.  Commonalities and Differences Among Vectorized Beamformers in Electromagnetic Source Imaging , 2003, Brain Topography.

[100]  Arjan Hillebrand,et al.  The temporal frequency tuning of human visual cortex investigated using synthetic aperture magnetometry , 2004, NeuroImage.

[101]  Gareth R. Barnes,et al.  Dissociating the spatio-temporal characteristics of cortical neuronal activity associated with human volitional swallowing in the healthy adult brain , 2004, NeuroImage.

[102]  Arjan Hillebrand,et al.  Spatio‐temporal Imaging of Cortical Desynchronization in Migraine Visual Aura: A Magnetoencephalography Case Study , 2004, Headache.

[103]  G. Barnes,et al.  Assessing interactions of linear and nonlinear neuronal sources using MEG beamformers: a proof of concept , 2005, Clinical Neurophysiology.

[104]  P. Berg,et al.  Use of prior knowledge in brain electromagnetic source analysis , 2005, Brain Topography.

[105]  Gareth R. Barnes,et al.  The missing link: analogous human and primate cortical gamma oscillations , 2005, NeuroImage.

[106]  W. Drongelen,et al.  A spatial filtering technique to detect and localize multiple sources in the brain , 1996, Brain Topography.