Fifty Years Of Magnetoencephalography

"In the fifty years since magnetoencephalography (MEG) was invented, various clinical and research applications of it have been attempted with considerable success. This is most notable in the area of epilepsy and pre-surgical functioning mapping. However, the best way to apply MEG and interpret the findings still remains conjectural. As such, this book assesses the new clinical and research applications of MEG, especially for markers of neuropsychiatric and other disorders. It also evaluates the new instruments and analytic procedures that have been recently developed. Ultimately, the book may serve as a standard of clinical practice and as a source of ideas for expanding the applications of MEG"--

"In the fifty years since magnetoencephalography (MEG) was invented, various clinical and research applications of it have been attempted with considerable success. This is most notable in the area of epilepsy and pre-surgical functioning mapping. However, the best way to apply MEG and interpret the findings still remains conjectural. As such, this book assesses the new clinical and research applications of MEG, especially for markers of neuropsychiatric and other disorders. It also evaluates the new instruments and analytic procedures that have been recently developed. Ultimately, the book may serve as a standard of clinical practice and as a source of ideas for expanding the applications of MEG"--

Fifty Years of Magnetoencephalography celebrates the first half century of research in and clinical applications of magnetoencephalography (MEG). It catalogs and documents its evolution as a means of imaging the ongoing activity of the brain and the activation of particular neuronal networks within it that mediate sensory motor and higher functions like language. The volume's first section looks at the discovery of MEG and its first tentative applications by three of its founders. The following sections detail the rapid progress in the development of the instrumentation necessary for recording noninvasively the magnetic signals on the head that are associated with the brain activity; improvements in the techniques for analyzing the magnetic signals and reconstructing, on their basis, the functional images of brain activity; and improvements in our understanding of the nature and significance of those signals. Subsequent sections of the book detail the main clinical applications of MEG in localizing brain areas that contain sources of epileptiform activity and areas encompassing parts of functional networks essential for motor and sensory function as well as for language that have become an essential part of planning for brain surgery in many epilepsy and tumor surgery centers around the world. In addition, several chapters describe the most current efforts aiming at expanding the utility of MEG in clinical diagnosis and theoretical research.

Magnetoencephalography (MEG) is an exciting brain imaging technology that allows real-time tracking of neural activity, making it an invaluable tool for advancing our understanding of brain function. In this comprehensive introduction to MEG, Peter Hansen, Morten Kringelbach, and Riitta Salmelin have brought together the leading researchers to provide the basic tools for planning and executing MEG experiments, as well as analyzing and interpreting the resulting data. Chapters on the basics describe the fundamentals of MEG and its instrumentation, and provide guidelines for designing experiments and performing successful measurements. Chapters on data analysis present it in detail, from general concepts and assumptions to analysis of evoked responses and oscillatory background activity. Chapters on solutions propose potential solutions to the inverse problem using techniques such as minimum norm estimates, spatial filters and beamformers. Chapters on combinations elucidate how MEG can be used to complement other neuroimaging techniques. Chapters on applications provide practical examples of how to use MEG to study sensory processing and cognitive tasks, and how MEG can be used in a clinical setting. These chapters form a complete basic reference source for those interested in exploring or already using MEG that will hopefully inspire them to try to develop new, exciting approaches to designing and analyzing their own studies. This book will be a valuable resource for researchers from diverse fields, including neuroimaging, cognitive neuroscience, medical imaging, computer modelling, as well as for clinical practitioners.

Research on the human brain development has seen an upturn in the past years mostly due to novel neuroimaging tools that became available to study the anatomy and function of the developing brain. Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI) are beginning to be used more frequently in children to determine the gross anatomy and structural connectivity of their brain. Functional MRI and Near-Infrared Spectroscopy (NIRS) determine the hemodynamics and electroencephalography (EEG) the electrophysiological functions of the developing human brain. Magnetoencephalography (MEG) complements EEG as the only other technique capable of directly measuring the developing brain electrophysiology. Although MEG is still being used relatively rarely in pediatric studies, the recent development in this technology is beginning to demonstrate its utility in both basic and clinical neurosciences. MEG seems to be quite attractive for pediatric use, since it measures the human brain activity in an entirely passive manner without possessing any conceivable risk to the developing tissue. MEG sessions generally require minimal patient preparation, and the recordings are extremely well tolerated from children. Biomagnetic techniques also offer an indirect way to assess the functional brain and heart activity of fetuses in humans in utero by measuring the magnetic field outside the maternal abdomen. Magnetic field produced by the electrical activity in the heart and brain of the fetus is not attenuated by the vernix, a waxy film covering its entire skin. A biomagnetic instrument specifically designed for fetal studies has been developed for this purpose. Fetal MEG studies using such a system have shown that both spontaneous brain activity and evoked cortical activity can be measured from outside the abdomen of pregnant mothers. Fetal MEG may become clinically very useful for implementation and evaluation of intervention programs in at-risk populations. Biomagnetic instruments have also been developed for specifically measuring the brain activity in newborns, infants and older children. MEG studies have shown the usefulness of MEG for localizing active regions in the brain and also for tracking the longitudinal maturation of various sensory systems. Studies of pediatric patients are beginning to show interesting functional pathology in autism spectrum disorder, cerebral palsy, epilepsy and other types of neurological and psychiatric disorders (Down syndrome, traumatic brain injury, Tourette syndrome, hearing deficits, childhood migraine). In this eBook, we compile the state of the art MEG and other neuroimaging studies focused on pediatric population in both health and disease. We believe a review of the recent studies of human brain development using MEG is quite timely, since we are witnessing advances not only in the instrumentation optimized for the pediatric population, but also in the research based on various types of MEG systems designed for both human fetuses in utero and neonates and older children.