Download or read book Parallelization of the Forward and Inverse Problems of Electro magnetic Source Imaging of the Human Brain written by Can Erkin Acar and published by . This book was released on 2003 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetic Source Imaging of the Human Brain written by Zhong-Lin Lu and published by Taylor & Francis. This book was released on 2003-10-17 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed to acquaint serious students, scientists, and clinicians with magnetic source imaging (MSI)--a brain imaging technique of proven importance that promises even more important advances. The technique permits spatial resolution of neural events on a scale measured in millimeters and temporal resolution measured in milliseconds. Although widely mentioned in literature dealing with cognitive neuroscience and functional brain imaging, there is no single book describing both the foundations and actual methods of magnetoencephalopgraphy and its underlying science, neuromagnetism. This volume fills a long-standing need, as it is accessible to scientists and students having no special background in the field, and makes it possible for them to understand this literature and undertake their own research. A self-contained unit, this book covers MSI from beginning to end, including its relationship to allied technologies, such as electroencephalography and modern functional imaging modalities. In addition, the book: *introduces the field to the non-specialist, providing a framework for the rest of the book; *provides a thorough review of the physiological basis of MSI; *describes the mathematical bases of MSI--the forward and inverse problems; *outlines new signal processing methods that extract information from single-trial MEG; *depicts the early, as well as the most recent versions of MSI technology; *compares MSI with other imaging methodologies; *describes new paradigms and analysis techniques in applying MSI to study human perception and cognition, which are also applicable to EEG; and *reviews some of the most important results in MSI from the most prominent researchers and laboratories around the world.
Download or read book PARALLEL IMPLEMENTATION OF THE BOUNDARY ELEMENT METHOD FOR ELECTROMAGNETIC SOURCE IMAGING OF THE HUMAN BRAIN written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Human brain functions are based on the electrochemical activity and interaction of the neurons constituting the brain. Some brain diseases are characterized by abnormalities of this activity. Detection of the location and orientation of this electrical activity is called electro-magnetic source imaging (EMSI) and is of signicant importance since it promises to serve as a powerful tool for neuroscience. Boundary Element Method (BEM) is a method applicable for EMSI on realistic head geometries that generates large systems of linear equations with dense matrices. Generation and solution of these matrix equations are time and memory consuming due to the size of the matrices and high computational complexity of direct methods. This study presents a relatively cheap and e ective solution the this problem and reduces the processing times to clinically acceptable values using parallel cluster of personal computers on a local area network. For this purpose, a cluster of 8 workstations is used. A parallel BEM solver is implemented that distributes the model eciently to the processors. The parallel solver for BEM is developed using the PETSc library. The performance of the iv solver is evaluated in terms of CPU and memory usage for di erent number of processors. For a 15011 node mesh, a speed-up eciency of 97.5% is observed when computing transfer matrices. Individual solutions can be obtained in 520 ms on 8 processors with 94.2% parallellization eciency. It was observed that workstation clusters is a cost e ective tool for solving complex BEM models in clinically acceptable time. E ect of parallelization on inverse problem is also demonstrated by a genetic algorithm and very similar speed-up is obtained.
Download or read book Electromagnetic Inverse Applications for Functional Brain Imaging written by and published by . This book was released on 1997 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This project addresses an important mathematical and computational problem in functional brain imaging, namely the electromagnetic {open_quotes}inverse problem.{close_quotes} Electromagnetic brain imaging techniques, magnetoencephalography (MEG) and electroencephalography (EEG), are based on measurements of electrical potentials and magnetic fields at hundreds of locations outside the human head. The inverse problem is the estimation of the locations, magnitudes, and time-sources of electrical currents in the brain from surface measurements. This project extends recent progress on the inverse problem by combining the use of anatomical constraints derived from magnetic resonance imaging (MRI) with Bayesian and other novel algorithmic approaches. The results suggest that we can achieve significant improvements in the accuracy and robustness of inverse solutions by these two approaches.
Download or read book Adaptive Spatial Filters for Electromagnetic Brain Imaging written by Kensuke Sekihara and published by Springer Science & Business Media. This book was released on 2008-05-30 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neural activity in the human brain generates coherent synaptic and intracellular currents in cortical columns that create electromagnetic signals which can be measured outside the head using magnetoencephalography (MEG) and electroencephalography (EEG). Electromagnetic brain imaging refers to techniques that reconstruct neural activity from MEG and EEG signals. Electromagnetic brain imaging is unique among functional imaging techniques for its ability to provide spatio-temporal brain activation profiles that reflect not only where the activity occurs in the brain but also when this activity occurs in relation to external and internal cognitive events, as well as to activity in other brain regions. Adaptive spatial filters are powerful algorithms for electromagnetic brain imaging that enable high-fidelity reconstruction of neuronal activity. This book describes the technical advances of adaptive spatial filters for electromagnetic brain imaging by integrating and synthesizing available information and describes various factors that affect its performance. The intended audience include graduate students and researchers interested in the methodological aspects of electromagnetic brain imaging.
Download or read book Brain Signals written by Risto J. Ilmoniemi and published by MIT Press. This book was released on 2019-05-28 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unified treatment of the generation and analysis of brain-generated electromagnetic fields. In Brain Signals, Risto Ilmoniemi and Jukka Sarvas present the basic physical and mathematical principles of magnetoencephalography (MEG) and electroencephalography (EEG), describing what kind of information is available in the neuroelectromagnetic field and how the measured MEG and EEG signals can be analyzed. Unlike most previous works on these topics, which have been collections of writings by different authors using different conventions, this book presents the material in a unified manner, providing the reader with a thorough understanding of basic principles and a firm basis for analyzing data generated by MEG and EEG. The book first provides a brief introduction to brain states and the early history of EEG and MEG, describes the generation of electromagnetic fields by neuronal activity, and discusses the electromagnetic forward problem. The authors then turn to EEG and MEG analysis, offering a review of linear and matrix algebra and basic statistics needed for analysis of the data, and presenting several analysis methods: dipole fitting; the minimum norm estimate (MNE); beamforming; the multiple signal classification algorithm (MUSIC), including RAP-MUSIC with the RAP dilemma and TRAP-MUSIC, which removes the RAP dilemma; independent component analysis (ICA); and blind source separation (BSS) with joint diagonalization.
Download or read book Magnetoencephalography An Issue of Neuroimaging Clinics of North America written by Roland Lee and published by Elsevier Health Sciences. This book was released on 2020-06-21 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: This issue of Neuroimaging Clinics of North America focuses on Magnetoencephalography (MEG), and is edited by Drs. Roland Lee and Mingxiong Huang. Articles will include: MEG signal processing, forward modeling, MEG inverse source imaging, and Coherence analysis; Magnetoencephalography for pre-surgical functional mapping; Magnetoencephalography for mild TBI and PTSD; Magnetoencephalography for autism; Magnetoencephalography for schizophrenia; Magnetoencephalography for Alzheimer's disease; Pediatric Magnetoencephalography; The MEG Measurement Techniques; MEG and Language/Linguistics; MEG for Epilepsy; Integration of MEG results into the patient workup – Merging multiple modalities; and more!
Download or read book Towards Electromagnetic Source Imaging Methods for Developing Brain computer Interface Neurotherapeutics written by Alejandro Ojeda and published by . This book was released on 2019 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite several decades of research, most mental health treatments are based on pharmacological manipulations that globally affect the nervous system. Such treatments often lead to undesired side effects and short term symptomatic relief. The difficulty of diagnosing and treating mental health illnesses stems from the overwhelming complexity of the brain and is exacerbated by the fact that our ability to probe, simultaneously, the activity of dynamic and distributed brain networks is limited. In this dissertation, I propose an alternative way to tackle the mental health problem by using high-resolution imaging-based brain-computer interface (BCI) neurotechnology. I focus on new neuroimaging technology that allows us to monitor the electrical activity of cortical networks at low-cost and high spatiotemporal resolution using noninvasive electroencephalographic (EEG) measurements. This technology will serve as the "neural decoder" component of yet to come imaging-based closed-loop systems that can effectively restore impaired cognition. The decoder allows a BCIs to dynamically probe specific cognitive abilities of the subject in search for signatures of circuit dysfunctions. Then, various types of feedback can be designed to induce the engagement of neural populations that can compensate for the detected aberrant neuronal activity. In this dissertation, first, I develop the mathematical framework to efficiently map scalp EEG responses back into the cortical space, and by doing so, I show that the biological mechanisms responsible for the neurocognitive processes of interest are easy to study. Of theoretical and practical relevance, I demonstrate that this framework successfully unifies three of the most common problems in EEG analysis: data cleaning, source separation, and imaging. Then, I develop the algorithmic and software machinery necessary to implement high-resolution imaging-based BCIs. Finally, I analyze data from healthy adults performing a self-paced unconstrained schoolwork-like computerized task and show that within the proposed framework, I can identify brain network correlates of attention switches at a millisecond time scale. Since attention-related dysfunctions are linked to several psychiatric disorders, these results represent a step forward towards developing BCI interventions to treat several mental health illnesses.
Download or read book Magnetic source imaging of visually evoked and oscillatory electrical activity of the human brain written by Seppo Ahlfors and published by . This book was released on 1994 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recent Advances in Human Brain Mapping written by International Society for Brain Electromagnetic Topography. World Congress and published by . This book was released on 2002 with total page 966 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings cover a wide range of topics in the field of brain function mapping; from basic neuroscience to clinical applications. It provides an important overview of brain mapping research and will be useful reading for the neuroscientist who intends to clarify the brain function using physiological or imaging techniques. Techniques used include EEG, ERP, PET, SPECT, MEG, MRI, MRS, fMRI and optic topography.
Download or read book Clinical Magnetoencephalography and Magnetic Source Imaging written by Andrew C. Papanicolaou and published by Cambridge University Press. This book was released on 2009-08-13 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first volume on clinical magnetoencephalography and magnetic source imaging, measuring the magnetic fields generated by neuronal activity in the brain.
Download or read book Emerging Electromagnetic Technologies for Brain Diseases Diagnostics Monitoring and Therapy written by Lorenzo Crocco and published by Springer. This book was released on 2018-03-10 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: This timely book presents innovative technologies for use in the diagnosis, monitoring, and treatment of brain disease. These technologies offer exciting possibilities in the medical field owing to their low-cost, portability and safety. The authors address cerebrovascular diseases such as stroke, ischemia, haemorrhage, and vasospasm, these diseases having an ever-increasing societal relevance due to the global ageing population. The authors describe the potential of novel techniques such as microwave imaging and present innovative modalities for treatment of brain tumours using electromagnetic fields and nano-composites, as well as for monitoring brain temperature during surgery. Finally, Emerging Electromagnetic Technologies for Brain Diseases Diagnostics, Monitoring and Therapy addresses the perspectives which arise from multi-modal multi-spectral EM modalities, which make a synergic use of the different portions of the electromagnetic spectrum. This text will be of interest to readers from various different areas, given the fundamental interdisciplinarity of the subject matter. This includes researchers or practitioners in the field of electrical engineering, applied physicists, and applied mathematicians working on imaging applications for biomedical and electromagnetic technologies. Neurologists and radiologists may also find this book of interest, as may graduate students in these areas.
Download or read book Working with MEG written by Gavin Perry and published by Taylor & Francis. This book was released on 2022-10-14 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1968 at the University of Illinois, David Cohen made scientific history when he measured a neuronal oscillation known as the alpha rhythm from the brains of four human volunteers. The measurement of the alpha rhythm was not in itself a breakthrough: the German psychiatrist, Hans Berger, had discovered the rhythm decades earlier during his first recordings of human electroencephalography (EEG). What was novel about Cohen’s experiment was that it did not measure electrical potentials on the scalp as is the case for EEG. Instead, the measurements were made using a metal coil built to measure magnetic fields. Cohen had become the first person to measure the brain’s magnetic field and in doing so had pioneered an entirely new method for measuring the brain’s activity: magnetoencephalograpy (MEG). In the intervening decades MEG has grown from a highly specialised method practiced by a small number of researchers to a routine method of human neuroscience available at laboratories across the world. However, as the use of MEG has increased, so too has the number of people encountering MEG for the first time, and this has created a growing need for materials that aid the understanding of MEG for those with no prior experience.
Download or read book Biomag 2004 written by Eric Halgren and published by . This book was released on 2004 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parallel Transmission for Magnetic Resonance Imaging of the Human Brain at Ultra High Field written by Martijn Anton Hendrik Cloos and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this thesis lies on the development, and implementation, of parallel transmission (pTx) techniques in magnetic resonance imaging for flip-angle homogenization throughout the human brain at ultra-high field. In order to allow in-vivo demonstrations, a conservative yet viable safety concept is introduced to control the absorbed radiofrequency (RF) power . Subsequently, novel methods for local SAR control and non-selective RF pulse-design are investigated. The impact of these short and energy-efficient waveforms, referred to as kT-points, is first demonstrated in the context of the small-tip-angle domain. Targeting a larger scope of applications, the kT-points design is then generalized to encompass large flip angle excitations and inversions. This concept is applied to one of the most commonly used T1-weighted sequences in neuroimaging. Results thus obtained at 7 Tesla are compared to images acquired with a clinical setup at 3 Tesla, validating the principles of the kT-points method and demonstrating that pTx-enabled ultra-high field systems can also be competitive in the context of T1-weighted imaging. Finally, simplifications in the global design of the pTx-implementation are studied in order to obtain a more cost-effective solution.
Download or read book Functional Brain Imaging written by Gert Pfurtscheller and published by Hogrefe & Huber Publishing. This book was released on 1988 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a unique and richly illustrated book that concisely explains topographic mapping of electrical and magnetic brain activity, and relates this technique to metabolic and regional blood flow studies. Also addressed are important results of experimental and clinical investigations, as well as problems of electrical magnetic data and topographic display.
Download or read book Electromagnetic Brain Imaging written by Kensuke Sekihara and published by Springer. This book was released on 2016-10-06 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This graduate level textbook provides a coherent introduction to the body of main-stream algorithms used in electromagnetic brain imaging, with specific emphasis on novel Bayesian algorithms. It helps readers to more easily understand literature in biomedical engineering and related fields and be ready to pursue research in either the engineering or the neuroscientific aspects of electromagnetic brain imaging. This textbook will not only appeal to graduate students but all scientists and engineers engaged in research on electromagnetic brain imaging.
