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Practical Neurology Oct 2014
Review
Topics: Brain; Brain Mapping; Humans; Magnetoencephalography; Neurodegenerative Diseases; Neuroimaging
PubMed: 24647614
DOI: 10.1136/practneurol-2013-000768 -
Journal of Clinical Neurophysiology :... Nov 2020Normal variants, although not occurring frequently, may appear similar to epileptic activity. Misinterpretation may lead to false diagnoses. In the context of... (Review)
Review
Normal variants, although not occurring frequently, may appear similar to epileptic activity. Misinterpretation may lead to false diagnoses. In the context of presurgical evaluation, normal variants may lead to mislocalizations with severe impact on the viability and success of surgical therapy. While the different variants are well known in EEG, little has been published in regard to their appearance in magnetoencephalography. Furthermore, there are some magnetoencephalography normal variants that have no counterparts in EEG. This article reviews benign epileptiform variants and provides examples in EEG and magnetoencephalography. In addition, the potential of oscillatory configurations in different frequency bands to appear as epileptic activity is discussed.
Topics: Action Potentials; Brain; Electroencephalography; Epilepsy; Humans; Magnetoencephalography
PubMed: 33165225
DOI: 10.1097/WNP.0000000000000484 -
Nature Neuroscience Feb 2017We review the aspects that uniquely characterize magnetoencephalography (MEG) among the techniques available to explore and resolve brain function and dysfunction. While... (Review)
Review
We review the aspects that uniquely characterize magnetoencephalography (MEG) among the techniques available to explore and resolve brain function and dysfunction. While emphasizing its specific strengths in terms of millisecond source imaging, we also identify and discuss current practical challenges, in particular in signal extraction and interpretation. We also take issue with some perceived disadvantages of MEG, including the misconception that the technique is redundant with electroencephalography. Overall, MEG contributes uniquely to our deeper comprehension of both regional and large-scale brain dynamics: from the functions of neural oscillations and the nature of event-related brain activation, to the mechanisms of functional connectivity between regions and the emergence of modes of network communication in brain systems. We expect MEG to play an increasing and pivotal role in the elucidation of these grand mechanistic principles of cognitive, systems and clinical neuroscience.
Topics: Brain; Brain Mapping; Electroencephalography; Electrophysiological Phenomena; Humans; Image Processing, Computer-Assisted; Magnetoencephalography
PubMed: 28230841
DOI: 10.1038/nn.4504 -
Trends in Neurosciences Aug 2022Magnetoencephalography (MEG) measures human brain function via assessment of the magnetic fields generated by electrical activity in neurons. Despite providing... (Review)
Review
Magnetoencephalography (MEG) measures human brain function via assessment of the magnetic fields generated by electrical activity in neurons. Despite providing high-quality spatiotemporal maps of electrophysiological activity, current MEG instrumentation is limited by cumbersome field sensing technologies, resulting in major barriers to utility. Here, we review a new generation of MEG technology that is beginning to lift many of these barriers. By exploiting quantum sensors, known as optically pumped magnetometers (OPMs), 'OPM-MEG' has the potential to dramatically outperform the current state of the art, promising enhanced data quality (better sensitivity and spatial resolution), adaptability to any head size/shape (from babies to adults), motion robustness (participants can move freely during scanning), and a less complex imaging platform (without reliance on cryogenics). We discuss the current state of this emerging technique and describe its far-reaching implications for neuroscience.
Topics: Adult; Brain; Functional Neuroimaging; Humans; Magnetoencephalography
PubMed: 35779970
DOI: 10.1016/j.tins.2022.05.008 -
Handbook of Clinical Neurology 2019Magnetoencephalography (MEG) is the noninvasive measurement of the miniscule magnetic fields produced by electrical currents flowing in the brain-the same neuroelectric... (Review)
Review
Magnetoencephalography (MEG) is the noninvasive measurement of the miniscule magnetic fields produced by electrical currents flowing in the brain-the same neuroelectric activity that produces the EEG. MEG is one of several diagnostic tests employed in the evaluation of patients with epilepsy, but without the need to expose the patient to any potentially harmful agents. MEG is especially important in those being considered for epilepsy surgery, in whom accurate localization of the epileptic focus is paramount. While other modalities infer brain function indirectly by measuring changes in blood flow, metabolism, oxygenation, etc., MEG, as well as EEG, measures neuronal and synaptic function directly and, like EEG, MEG enjoys submillisecond temporal resolution. The measurement of magnetic fields provides information not only about the amplitude of the current but also its orientation. MEG picks up the magnetic field from neuromagnetometers surrounding the head in a helmet-shaped array of sensors. Clinical whole-head systems currently have 200-300 magnetic sensors, thereby offering very high resolution. The magnetic signals are not distorted by anatomy, because magnetic susceptibility is the same for all tissues, including the skull. Hence, MEG allows for a more accurate measurement and localization of brain activities than does EEG. Because one of its primary strengths is the ability to precisely localize electromagnetic activity within brain areas, MEG results are always coregistered to the patient's MRI. When combined in this way with structural imaging, it has been called magnetic source imaging (MSI), but MEG is properly understood as a clinical neurophysiologic diagnostic test. Signal processing and clinical interpretation in magnetoencephalography require sophisticated noise reduction and computerized mathematical modeling. Technological advances in these areas have brought MEG to the point where it is now part of routine clinical practice. MEG has become an indispensable part of the armamentarium at epilepsy centers where MEG laboratories are located, especially when patients are MRI-negative or where results of other structural and functional tests are not entirely concordant.
Topics: Brain; Electroencephalography; Epilepsy; Humans; Magnetoencephalography
PubMed: 31277848
DOI: 10.1016/B978-0-444-64032-1.00013-8 -
Lancet (London, England) Mar 1990
Comparative Study Review
Topics: Electroencephalography; Evaluation Studies as Topic; Evoked Potentials; Humans; Magnetoencephalography
PubMed: 1968579
DOI: No ID Found -
Journal of Neurophysiology Mar 2021Magnetoencephalography (MEG) is a technique used to measure the magnetic fields generated from neuronal activity in the brain. MEG has a high temporal resolution on the... (Review)
Review
Magnetoencephalography (MEG) is a technique used to measure the magnetic fields generated from neuronal activity in the brain. MEG has a high temporal resolution on the order of milliseconds and provides a more direct measure of brain activity when compared with hemodynamic-based neuroimaging methods such as magnetic resonance imaging and positron emission tomography. The current review focuses on basic features of MEG such as the instrumentation and the physics that are integral to the signals that can be measured, and the principles of source localization techniques, particularly the physics of beamforming and the techniques that are used to localize the signal of interest. In addition, we review several metrics that can be used to assess functional coupling in MEG and describe the advantages and disadvantages of each approach. Lastly, we discuss the current and future applications of MEG.
Topics: Action Potentials; Animals; Biophysical Phenomena; Brain; Humans; Magnetoencephalography; Neurosciences; Physics
PubMed: 33567968
DOI: 10.1152/jn.00530.2020 -
Arquivos de Neuro-psiquiatria Sep 2003
Review
Topics: Brain Mapping; Epilepsy; Humans; Language; Magnetoencephalography
PubMed: 15104394
DOI: No ID Found -
International Review of Neurobiology 2012Magnetoencephalography (MEG) is a noninvasive method which allows recordings of human brain activity with excellent temporal and good spatial resolution. In this... (Review)
Review
Magnetoencephalography (MEG) is a noninvasive method which allows recordings of human brain activity with excellent temporal and good spatial resolution. In this chapter, we review applications of MEG in neuromodulation. We provide an overview of studies which used MEG to optimize parameters for neuromodulation and to characterize the electrophysiological effects of brain stimulation. In particular, we discuss how MEG may be employed to study deep brain stimulation. In this context, we describe the problems arising from stimulation artifacts and present approaches to solve them.
Topics: Animals; Brain; Deep Brain Stimulation; Humans; Magnetoencephalography; Neurotransmitter Agents; Transcranial Magnetic Stimulation
PubMed: 23206680
DOI: 10.1016/B978-0-12-404706-8.00007-3 -
Advances in Neurobiology 2023Magnetoencephalography (MEG) detects synchronized activity within a neuronal network by measuring the magnetic field changes generated by intracellular current flow.... (Review)
Review
Magnetoencephalography (MEG) detects synchronized activity within a neuronal network by measuring the magnetic field changes generated by intracellular current flow. Using MEG data, we can quantify brain region networks with similar frequency, phase, or amplitude of activity and thereby identify patterns of functional connectivity seen with specific disorders or disease states. In this review, we examine and summarize MEG-based literature on functional networks in dystonias. Specifically, we inspect literature evaluating the pathogenesis of focal hand dystonia, cervical dystonia, embouchure dystonia, the effects of sensory tricks, treatment with botulinum toxin and deep brain stimulation, and rehabilitation approaches. This review additionally highlights how MEG has potential for application to clinical care of patients with dystonia.
Topics: Humans; Magnetoencephalography; Dystonia; Brain; Dystonic Disorders
PubMed: 37338700
DOI: 10.1007/978-3-031-26220-3_8