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Author: Chin-Chak Ho
Publisher: Open Dissertation Press
ISBN: 9781361042250
Category : Technology & Engineering
Languages : en
Pages : 258
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Book Description
This dissertation, "Multimodal MRI Investigation of Eye and Visual Brain" by Chin-chak, Ho, 何阡澤, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Although the eyes are physically isolated from the visual brain, the physiology and integrity of the eye are central to several eye diseases and neurodegeneration in the visual brain. MRI provides non-invasive, longitudinal and multi-parametric assessments of the visual system without depth limitation. The objective of this doctoral work is to develop and apply multimodal MRI for the assessment of aqueous humor dynamics, ocular fibrous tissue and visual pathway integrity in the visual system. The functional response in neural systems were further explored with BOLD and diffusion fMRI. Firstly, dynamic Gd-MRI was applied to visualize and assess aqueous humor dynamics upon sustained intraocular pressure elevation and pharmacological interventions. The results reflect the reduced gadolinium clearance upon microbead occlusion and respective drug actions after ocular hypotensive drug treatment. Abnormal gadolinium leakage into the vitreous was found in compromised aqueous-vitreous or blood-ocular barrier integrity. Gd-MRI allows spatiotemporal and quantitative evaluation of altered aqueous humor dynamics and ocular tissue permeability. Secondly, MAMRI was employed to reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure elevation. At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and collagen fiber crimps. Loaded sclera and cornea possessed significantly higher T2 and T2* than unloaded tissues at magic angle, suggestive of the changes in collagen fiber crimp and alignment. MAMRI can detect ocular fibrous microstructures without contrast agents, and can reveal their MR tissue property changes with IOP loading. Thirdly, multimodal MRI was utilized to investigate the effects of biomechanical or biochemical modulation on the sclera and cornea tissues. T2 in corneoscleral shell increased non-linearly with IOP loading and remained longer than unloaded tissues after being unpressurized. Biomechanical loading increased fractional anisotropy in the corneoscleral shell, while increasing glyceraldehyde and chondroitinase-ABC concentrations decreased diffusivities and increased magnetization transfer in cornea. Glyceraldehyde also increased magnetization transfer in sclera. The changes in MRI contrast mechanisms upon various modulation of the eye provide insight to the pathophysiological mechanisms in the corneoscleral shell and the efficacy of corneoscleral treatments. Fourthly, the effects of excitotoxic retinal injury on the retinal thickness, microstructual integrity and anterograde transport was evaluated in vivo by DTI, MEMRI and OCT. Directional diffusivities in the visual pathway and their correlations with retinal thickness suggested anterograde axonal degeneration and delayed demyelination along the visual pathway. The splenium of corpus callosum was reorganized at 4 weeks post injury. Furthermore, the NMDA-injured visual pathway showed reduced anterograde manganese transport. These results characterized the spatiotemporal changes in white matter integrity, the eye-brain relationships and structural-physiological relationships in the visual system. Lastly, BOLD and diffusion fMRI were used to explore the functional responses of neural systems. The efficacy of using unisensory stimuli to elicit cross-modal activation was examined by BOLD fMRI improving the understanding to cortical cross-modal activity and its influence
Author: Chin-Chak Ho
Publisher: Open Dissertation Press
ISBN: 9781361042250
Category : Technology & Engineering
Languages : en
Pages : 258
Get Book Here
Book Description
This dissertation, "Multimodal MRI Investigation of Eye and Visual Brain" by Chin-chak, Ho, 何阡澤, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Although the eyes are physically isolated from the visual brain, the physiology and integrity of the eye are central to several eye diseases and neurodegeneration in the visual brain. MRI provides non-invasive, longitudinal and multi-parametric assessments of the visual system without depth limitation. The objective of this doctoral work is to develop and apply multimodal MRI for the assessment of aqueous humor dynamics, ocular fibrous tissue and visual pathway integrity in the visual system. The functional response in neural systems were further explored with BOLD and diffusion fMRI. Firstly, dynamic Gd-MRI was applied to visualize and assess aqueous humor dynamics upon sustained intraocular pressure elevation and pharmacological interventions. The results reflect the reduced gadolinium clearance upon microbead occlusion and respective drug actions after ocular hypotensive drug treatment. Abnormal gadolinium leakage into the vitreous was found in compromised aqueous-vitreous or blood-ocular barrier integrity. Gd-MRI allows spatiotemporal and quantitative evaluation of altered aqueous humor dynamics and ocular tissue permeability. Secondly, MAMRI was employed to reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure elevation. At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and collagen fiber crimps. Loaded sclera and cornea possessed significantly higher T2 and T2* than unloaded tissues at magic angle, suggestive of the changes in collagen fiber crimp and alignment. MAMRI can detect ocular fibrous microstructures without contrast agents, and can reveal their MR tissue property changes with IOP loading. Thirdly, multimodal MRI was utilized to investigate the effects of biomechanical or biochemical modulation on the sclera and cornea tissues. T2 in corneoscleral shell increased non-linearly with IOP loading and remained longer than unloaded tissues after being unpressurized. Biomechanical loading increased fractional anisotropy in the corneoscleral shell, while increasing glyceraldehyde and chondroitinase-ABC concentrations decreased diffusivities and increased magnetization transfer in cornea. Glyceraldehyde also increased magnetization transfer in sclera. The changes in MRI contrast mechanisms upon various modulation of the eye provide insight to the pathophysiological mechanisms in the corneoscleral shell and the efficacy of corneoscleral treatments. Fourthly, the effects of excitotoxic retinal injury on the retinal thickness, microstructual integrity and anterograde transport was evaluated in vivo by DTI, MEMRI and OCT. Directional diffusivities in the visual pathway and their correlations with retinal thickness suggested anterograde axonal degeneration and delayed demyelination along the visual pathway. The splenium of corpus callosum was reorganized at 4 weeks post injury. Furthermore, the NMDA-injured visual pathway showed reduced anterograde manganese transport. These results characterized the spatiotemporal changes in white matter integrity, the eye-brain relationships and structural-physiological relationships in the visual system. Lastly, BOLD and diffusion fMRI were used to explore the functional responses of neural systems. The efficacy of using unisensory stimuli to elicit cross-modal activation was examined by BOLD fMRI improving the understanding to cortical cross-modal activity and its influence
Author: Chin-Chak Ho
Publisher:
ISBN: 9781361042274
Category :
Languages : en
Pages :
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Book Description
This dissertation, "Multimodal MRI Investigation of Eye and Visual Brain" by Chin-chak, Ho, 何阡澤, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Although the eyes are physically isolated from the visual brain, the physiology and integrity of the eye are central to several eye diseases and neurodegeneration in the visual brain. MRI provides non-invasive, longitudinal and multi-parametric assessments of the visual system without depth limitation. The objective of this doctoral work is to develop and apply multimodal MRI for the assessment of aqueous humor dynamics, ocular fibrous tissue and visual pathway integrity in the visual system. The functional response in neural systems were further explored with BOLD and diffusion fMRI. Firstly, dynamic Gd-MRI was applied to visualize and assess aqueous humor dynamics upon sustained intraocular pressure elevation and pharmacological interventions. The results reflect the reduced gadolinium clearance upon microbead occlusion and respective drug actions after ocular hypotensive drug treatment. Abnormal gadolinium leakage into the vitreous was found in compromised aqueous-vitreous or blood-ocular barrier integrity. Gd-MRI allows spatiotemporal and quantitative evaluation of altered aqueous humor dynamics and ocular tissue permeability. Secondly, MAMRI was employed to reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure elevation. At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and collagen fiber crimps. Loaded sclera and cornea possessed significantly higher T2 and T2* than unloaded tissues at magic angle, suggestive of the changes in collagen fiber crimp and alignment. MAMRI can detect ocular fibrous microstructures without contrast agents, and can reveal their MR tissue property changes with IOP loading. Thirdly, multimodal MRI was utilized to investigate the effects of biomechanical or biochemical modulation on the sclera and cornea tissues. T2 in corneoscleral shell increased non-linearly with IOP loading and remained longer than unloaded tissues after being unpressurized. Biomechanical loading increased fractional anisotropy in the corneoscleral shell, while increasing glyceraldehyde and chondroitinase-ABC concentrations decreased diffusivities and increased magnetization transfer in cornea. Glyceraldehyde also increased magnetization transfer in sclera. The changes in MRI contrast mechanisms upon various modulation of the eye provide insight to the pathophysiological mechanisms in the corneoscleral shell and the efficacy of corneoscleral treatments. Fourthly, the effects of excitotoxic retinal injury on the retinal thickness, microstructual integrity and anterograde transport was evaluated in vivo by DTI, MEMRI and OCT. Directional diffusivities in the visual pathway and their correlations with retinal thickness suggested anterograde axonal degeneration and delayed demyelination along the visual pathway. The splenium of corpus callosum was reorganized at 4 weeks post injury. Furthermore, the NMDA-injured visual pathway showed reduced anterograde manganese transport. These results characterized the spatiotemporal changes in white matter integrity, the eye-brain relationships and structural-physiological relationships in the visual system. Lastly, BOLD and diffusion fMRI were used to explore the functional responses of neural systems. The efficacy of using unisensory stimuli to elicit cross-modal activation was examined by BOLD fMRI improving the understanding to cortical cross-modal activity and its influence
Author: Yan Tong
Publisher: Frontiers Media SA
ISBN: 2832516041
Category : Science
Languages : en
Pages : 153
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Book Description
Author: Bin Jing
Publisher: Frontiers Media SA
ISBN: 2832547591
Category : Science
Languages : en
Pages : 197
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Book Description
Nowadays, exploring the brain-behavior relationship via MRI, EEG, fNIRS, and MEG has become a research hotspot further accelerated by the emergence of large-sample open-source datasets, such as UK Biobank, Human Connectome Project, the Adolescent Brain Cognitive Development, the National Institute of Mental Health (NIMH) Intramural Healthy Volunteer Dataset, the TUH EEG CORPUS, and many other multimodal datasets. Many prior studies have conducted various prediction tasks in different populations (from infants to adults; from healthy subjects to patients) with miscellaneous imaging modalities, however, to construct a precise, generalizable, and reproducible brain-behavior relationship is still facing many challenges, for example, individual variability, multi-site heterogeneity, imaging result interpretability, model generalization, low prediction performance, and lack of clinical applications
Author: Xin Huang
Publisher: Frontiers Media SA
ISBN: 2832536107
Category : Science
Languages : en
Pages : 202
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Book Description
Author: Hyder Fahmeed
Publisher: Humana Press
ISBN: 9781934115749
Category : Medical
Languages : en
Pages : 0
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Book Description
If a picture is worth a thousand words, then dynamic images of brain activity certainly warrant many, many more. This book will help users learn to decipher the dynamic imaging data that will be critical to our future understanding of complex brain functions. In recent years, there have been unprecedented methodological advancements in the imaging of brain activity. These techniques allow the measurement of everything from neural activity (e.g., membrane potential, ion ?ux, neurotransmitter ?ux) to energy metabolism (e.g., glucose consumption, oxygen consumption, creatine kinase ?ux) and functional hyperemia (e.g., blood ?ow, volume, oxygenation). This book deals with a variety of magnetic resonance, electrophysiology, and optical methods that are often used to measure some of these dynamic processes. All chapters were written by leading experts, spanning three continents, specializing in state-of-the-art methods. Brie?y, the book has ?ve sections. In the introductory section, there are two chapters; the ?rst one contains a brief pre- ble to dynamic brain imaging and the other presents a novel, analytical approach to processing of dynamically acquired data. The second section has four chapters and delves into a wide range of optical imaging methods. I am privileged to include a chapter from Lawrence B. Cohen, considered by many to be the authority on optical imaging and spectroscopy, both in vitro and in vivo [Cohen LB (1973) Physiol Rev.
Author: Stefan Blüml
Publisher: Springer Science & Business Media
ISBN: 1441958649
Category : Medical
Languages : en
Pages : 405
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Book Description
Magnetic resonance spectroscopy (MRS) is a modality available on most clinical MR scanners and readily integrated with standard MR imaging (MRI). For the brain in particular, MRS has been a powerful research tool providing additional clinically relevant information for several disease families such as brain tumors, metabolic disorders, and systemic diseases. The most widely-available MRS method, proton (1H; hydrogen) spectroscopy, is FDA approved for general use in the US and can be ordered by clinicians for patient studies if indicated. There are several books available that describe applications of MRS in adults. However, to the best of our knowledge there is currently no book available that focuses exclusively on applications in pediatrics. MR spectroscopy in the pediatric population is different from adults for two main reasons. Particularly in the newborn phase the brain undergoes biochemical maturation with dramatic changes of the "normal" biochemical fingerprint. Secondly, brain diseases in the pediatric population are different from adult disorders. For example, brain tumors, which are mostly gliomas in the adults, often originate from different cell types and are also more diverse even within the same type and grade of tumor. This diversity of diseases and its implications for MR spectroscopy has not been addressed sufficiently in the literature, we believe. The target audience for "MR Spectroscopy of Pediatric Brain Disorders" are thus both clinicians and researchers involved with pediatric brain disorders. This includes radiologists, neurologists, neurooncologists, neurosurgeons, and more broadly the neuroscience and neurobiology community. This book will provide the necessary background information to understand the basics of MR spectroscopy. This will be followed by a detailed discussion of the normal biochemical maturation which will highlight the metabolic differences between the pediatric and adult brain. Thereafter, in SECTION I individual chapters will address various pediatric brain disease families. Of particular importance for pediatrics are case studies. For that reason, SECTION II will contain a large number of case studies. This will be particularly important for clinicians who may want to see examples of MRS for various conditions. A standardized format will be used for case reports that allow the reader to quickly understand the history of each case presented and the significance of the findings. The case reports will also include information from other imaging modalities to point out any added value of MRS in addition to conventional studies and clinical information. This section is necessary because the format of providing more complete information about individual patients is not practical for the chapters in SECTION I.
Author: R. John Leigh
Publisher: Oxford University Press, USA
ISBN: 0199969280
Category : Medical
Languages : en
Pages : 1137
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Book Description
"lt is a tremendous achievement to have provided this highly comprehensive but readable text, which informs such a large group of researchers and clinicians." Christopher Kennard, PhD, FRCP, FMedSci, Professor of Clinical Neurology, Head, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom. "A monograph written with deep knowledge, understanding, wisdom, clarity, intelligibility - the superlatives could go on and on... A remarkable achievement and a great gift to all of us from the two modern giants of eye movement disorders." Michael Halmagyi, MD, Eye and Ear Research Unit, Neurology Department, Royal Prince Alfred Hospital, The University of Sydney, Australia. "The fifth edition of The Neurology of Eye Movements is a must for all neurologists and neuroscientists interested in how the human vestibular and oculomotor systems adapt to movement in space and to optimally viewing the world and its contents." Louis R. Caplan, MD, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
Author:
Publisher: Academic Press
ISBN: 0123973163
Category : Science
Languages : en
Pages : 2668
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Book Description
Brain Mapping: A Comprehensive Reference, Three Volume Set offers foundational information for students and researchers across neuroscience. With over 300 articles and a media rich environment, this resource provides exhaustive coverage of the methods and systems involved in brain mapping, fully links the data to disease (presenting side by side maps of healthy and diseased brains for direct comparisons), and offers data sets and fully annotated color images. Each entry is built on a layered approach of the content – basic information for those new to the area and more detailed material for experienced readers. Edited and authored by the leading experts in the field, this work offers the most reputable, easily searchable content with cross referencing across articles, a one-stop reference for students, researchers and teaching faculty. Broad overview of neuroimaging concepts with applications across the neurosciences and biomedical research Fully annotated color images and videos for best comprehension of concepts Layered content for readers of different levels of expertise Easily searchable entries for quick access of reputable information Live reference links to ScienceDirect, Scopus and PubMed
Author: Christoph Klein
Publisher: Springer Nature
ISBN: 303020085X
Category : Psychology
Languages : en
Pages : 1017
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Book Description
This edited volume presents fundamentals as well as applications of oculomotor methods in industrial and clinical settings. The topical spectrum covers 1.) basics and background material, 2.) methods such as recording techniques, markov models, Lévy flights, pupillometry and many more, as well as 3.) a broad range of applications in clinical and industrial settings. The target audience primarily comprises research experts and practitioners, but the book may also be beneficial for graduate students.
