Magnetoencephalography in the study of brain dynamics (original) (raw)
Related papers
Magnetoencephalography: From Signals to Dynamic Cortical Networks
Published in 2014, 2014
The existence of a structured pattern of neuronal activity in the brain at rest has been consistently reported in the neuroscience literature. Multiple techniques, such as fMRI, MEG, and EEG, showed that spontaneous, slow fluctuations of cerebral activity are temporally coherent within distributed functional networks resembling those evoked by sensory, motor, and cognitive paradigms. Among these networks, the Default Mode network gained large interest because of its anatomical and functional architecture. In fact, this network seems to reflect the
Magnetoencephalography as a research tool in neuroscience: state of the art
The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry, 2006
Magnetoencephalography (MEG) is a noninvasive neuroimaging method for detecting, analyzing, and interpreting the magnetic field generated by the electrical activity in the brain. Modern hardware can capture the MEG signal at hundreds of points around the head in a snapshot lasting only a fraction of a millisecond. The sensitivity of modern hardware is high enough to permit the extraction of a clean signal generated by the brain well above the noise level of the MEG hardware. It is possible to identify signatures of superficial and often deep generators in the raw MEG signal, even in snapshots of data. In a more quantitative way, tomographic images of the electrical current density in the brain can be extracted from each snapshot of MEG signal, providing a direct correlate of coherent collective neuronal activity. A number of recent studies have scrutinized brain function in the new spatiotemporal window that real-time tomographic analysis of MEG signals has opened. The results have ...
A new approach to neuroimaging with magnetoencephalography
Human Brain Mapping, 2005
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.
Magnetoencephalography in studies of human cognitive brain function
Trends in Neurosciences, 1994
Magnetoencephalography provides a new dimension to the functional imaging of the brain. The cerebral magnetic fields recorded noninvasively enable the accurate determination of locations of cerebral activ@ with an uncompromized time resolution. The first whole-scalp sensor arrays have just recently come into operation, and significant advances are to be expected in both neurophysiological and cognitive studies, as well as in clinical practice. However, although the accuracy of locating isolated sources of brain activity has improved, identification of multiple simultaneous sources can still be a problem. Therefore, attempts are being made to combine magnetoencephalography with other brainimaging methods to improve spatial localization of multiple sources and, simultaneously, to achieve a more complete characterization of different aspects qf brain activi& during cognitive processing. Owing to its good time resolution and considerably better spatial accuracy than that provided by E E G, magnetoencephalography holds great promise as a tool for revealing informationprocessing sequences of the human brain.
Information processing in the human brain: magnetoencephalographic approach
Proceedings of the National Academy of Sciences, 1996
Rapid progress in effective methods to image brain functions has revolutionized neuroscience. It is now possible to study noninvasively in humans neural processes that were previously only accessible in experimental animals and in brain-injured patients. In this endeavor, positron emission tomography has been the leader, but the superconducting quantum interference device-based magnetoencephalography (MEG) is gaining a firm role, too. With the advent of instruments covering the whole scalp, MEG, typically with 5-mm spatial and 1-ms temporal resolution, allows neuroscientists to track cortical functions accurately in time and space. We present five representative examples of recent MEG studies in our laboratory that demonstrate the usefulness of whole-head magnetoencephalography in investigations of spatiotemporal dynamics of cortical signal processing.
Synchronous dynamic brain networks revealed by magnetoencephalography
Proceedings of the National Academy of Sciences of the United States of America, 2006
We visualized synchronous dynamic brain networks by using prewhitened (stationary) magnetoencephalography signals. Data were acquired from 248 axial gradiometers while 10 subjects fixated on a spot of light for 45 s. After fitting an autoregressive integrative moving average model and taking the residuals, all pairwise, zero-lag, partial cross-correlations (PCC(ij)(0)) between the i and j sensors were calculated, providing estimates of the strength and sign (positive and negative) of direct synchronous coupling between neuronal populations at a 1-ms temporal resolution. Overall, 51.4% of PCC(ij)(0) were positive, and 48.6% were negative. Positive PCC(ij)(0) occurred more frequently at shorter intersensor distances and were 72% stronger than negative ones, on the average. On the basis of the estimated PCC(ij)(0), dynamic neural networks were constructed (one per subject) that showed distinct features, including several local interactions. These features were robust across subjects an...
Journal of Neural Engineering, 2007
We report on a test to assess the dynamic brain function at high temporal resolution using magnetoencephalography (MEG). The essence of the test is the measurement of the dynamic synchronous neural interactions, an essential aspect of the brain function. MEG signals were recorded from 248 axial gradiometers while 142 human subjects fixated a spot of light * Contribution by the authors: Designed research (APG); acquired data (AAA, IGK, FJPL, ACL, SML,
Magnetoencephalography as a Tool in Psychiatric Research: Current Status and Perspective
Biological psychiatry : cognitive neuroscience and neuroimaging, 2017
The application of neuroimaging to provide mechanistic insights into circuit dysfunctions in major psychiatric conditions and the development of biomarkers are core challenges in current psychiatric research. We propose that recent technological and analytic advances in magnetoencephalography (MEG), a technique that allows measurement of neuronal events directly and noninvasively with millisecond resolution, provides novel opportunities to address these fundamental questions. Because of its potential in delineating normal and abnormal brain dynamics, we propose that MEG provides a crucial tool to advance our understanding of pathophysiological mechanisms of major neuropsychiatric conditions, such as schizophrenia, autism spectrum disorders, and the dementias. We summarize the mechanisms underlying the generation of MEG signals and the tools available to reconstruct generators and underlying networks using advanced source-reconstruction techniques. We then surveyed recent studies tha...