Download or read book Phase Resolved Optical Coherence Tomography for Label free Detection of Neural Activity written by Minh Quang Tong and published by . This book was released on 2018 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current methods for detection of nervous system activity have been limited to electrophysiology, which requires the electrode to contact the nervous system or optical-based techniques that require incorporation of reporter agents. Both methods are golden standards but have limitations. Optical coherence tomography (OCT) is an imaging technique based on light that measures intrinsic structural changes associated with an action potential. A benefit of using OCT is that it does not require any exogenous agents and is minimally invasive. Phase-resolved OCT detects 1-30 nm swelling of an axon during neural activity. In my studies described here, phase-resolved OCT was used to detect the swelling Drosophila neurons when presented with ecdysis triggering hormone as well as a 1-3 nm swelling of a cockroach axon caused by action. However, since phase imaging is limited to one point, the dissertation ends with development of the line field swept source OCT system that can provide images of a b-line or cross-sectional image without using a scanning device.
Download or read book Progress Towards Detecting Neural Activity in Optical Coherence Tomography Using Phase written by Jasmine Kavan Shah and published by . This book was released on 2017 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) is non-invasive, real time optical imaging method based on low coherence interferometry with high resolution. It is capable of imaging microstructure by measuring the light backscattered from the sample. Under the AGI grant, I have built a Swept Source OCT (SS-OCT) / phase resolved OCT to detect the nanometer(nm) scale changes in the cell membrane that occur during membrane depolarization and Ion influx. This type of small changes can be seen using phase. Intensity is robust but is less sensitive to the small-scale changes whereas phase is highly sensitive. The noise level for phase difference quantification depends on the lateral motion, triggering of the wavelength mismatch and signal to noise ratio (SNR). To detect the nm scale changes phase noise should be minimum. The phase noise is inversely proportional to SNR. The SNR of the system should be maximum. The SS-OCT has swept source with sweep rate 100 kHz and it is not phase stable. It needs post processing algorithm to match the triggering wavelength to stabilize the phase. I wrote the code in GPU to reduce the computation time for post processing algorithm. Due to a few setbacks related to moving the system to a collaborating lab, the biological portion of my thesis work, trying to find the neural activity in the walking leg nerve of the Lobster using phase, was done with a spectral domain OCT (SD-OCT). To see any action potential change in the nerve I realigned the SD-OCT system with center wavelength to increase the SNR of the system and the sample arm with the nerve chamber (3D printed) to stimulate the nerve at one end and take the OCT image at the other end to see the action potential.
Download or read book Optical Coherence Tomography for Structural Neuroimaging and Non contact Recording of Functionally Stimulated Neural Activity written by Md Shahidul Islam and published by . This book was released on 2013 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nerve activity in a biological neural network is mostly characterized by generation and propagation of impulses through the nerves. These impulses, known as action potentials, are generated when the nerves are excited by a stimulus either as an external input or as a means of internal communication between nerves. This project is aimed to develop an optical imaging based minimally invasive technique for neural recording. Existing technologies largely limit the analysis of neuronal processing to a single or small cluster of neurons using different varieties of electrodes or the introduction of exogenous contrast agents and most of these techniques are invasive in some ways. Nerves undergo rapid transient thickness changes during propagation of action potentials. These activity associated structural changes are usually in the order of nanometers which is well beyond the usual limit of resolution of most common imaging technologies, including optical coherence tomography (OCT). However, recent advances in phase-resolved OCT (pr-OCT), a specific modality of OCT, have enabled the measurement of subnanometer changes in optical path length. This study demonstrates pr-OCT's capability to detect and measure rapid transient thickness changes in nerves during activity. Optically detected changes in nerve fiber thickness have timing and duration similar to the propagating electrical signal recorded in electrophysiology. Averaging of 8-10 impulses improves the SNR of detected optical signal. However, most of the results demonstrated here are single shot detections. Since OCT collects data from every depth points within a single A-line simultaneously, the changes in phase at every depth location are examined. Results demonstrate that these transient changes are present at different depths and this allows representing activity as a map of thickness changes. A custom-built cold block system has been used for switchable control of activation and deactivation of action potential propagation through the Limulus nerve. Optical recording has been compared with simultaneous electrical recording at every stages of cold block operation: activated nerve before deactivation, nerve after deactivation and nerve after reactivation. Hopefully, this study will serve as the basic ground work for future experiments and will have an overall significant impact on functional neuroimaging.
Download or read book Temporally Registered Optical Coherence Tomography and Fluorescence Microscopy for in Vitro Detection of Neural Activity written by Md Rezuanul Haque and published by . This book was released on 2014 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current methods for investigating activity in neurons largely rely on different varieties of electrodes, which require direct or very close contact, or fluorescence-based techniques, which require chemical or genetic introduction of a voltage- or calcium-sensitive fluorophore. The primary motivation for this work was to develop an intensity (non-phase) based extension of optical coherence tomography (OCT), an optical technology capable of rapid imaging of subsurface tissue structure with micrometer resolution without the need for exogenous contrast agents, for in vitro detection of neural activity. First, a preliminary study of epileptiform activity in murine hippocampal brain slices was used as an assessment of OCT for in vitro detection of neural activity. Elevated potassium was used to induce seizure-like bursts of activity. Decreases in OCT light intensity were found to be correlated with the initial onset of large-scale activation using simultaneous electrophysiological detection with a multi-electrode array. These results motivated the development of a novel spatiotemporally co-registered OCT and fluorescence microscopy (FM) system capable of observing neural activity simultaneously with both modalities. The combined system was designed to provide sequential OCT volumetric imaging over an extended depth range with fluorescence imaging through a common objective. This allows for the results of analytical methods developed to endogenously detect neural activity based on OCT intensity to be correlated with changes in fluorescence. Finally, the system was used to observe neural circuitry in the brain of Drosophila pupae. The fluorescence response of GCaMP-3 labeled bursicon and kinin cells in response to presentation of ecdysis triggering hormone (ETH) is well-characterized. Time sequences of OCT volumetric data acquired over these neurons in in vitro adolescent Drosophila brain in response to presentation of ETH were analyzed and compared to simultaneously recorded fluorescence data. Changes in the backscattered OCT intensity in both cell types were found to correlate well with neural activity as identified by fluorescence. These results demonstrate the potential of OCT for in vitro detection of neural activity without the need for fluorescence contrast.
Download or read book Quantification of Changes of Intensity and Attenuation Coefficient During Neural Activity Using Optical Coherence Tomography written by Md. Monirul Hasan and published by . This book was released on 2018 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nervous system, which receives information through the electrical signal to coordinate and disseminate information about the body and its environment, is an assembly of neurons. Current methods of detection of neural activity are based on electrophysiology, which requires direct or near direct contact, or fluorescence-based techniques, which require the introduction of reporter molecules, raising a concern of toxicity. Optical coherence tomography (OCT) detects neural activity by taking advantage of intrinsic structural changes that accompany neural activity without any exogenous agents. The phase-resolved OCT detected 10-30 nm swelling of axon during neural activity from the functionally stimulated compound eye of the horseshoe crab (limulus) by utilizing the phase-resolved measurement. There was a decrease of backscattered intensity during propagation of action potential due to change of scattering as well. Further study on in vitro murine brain slice showed the changes of the phase (or thickness change) as well as a decrease of back-reflected intensity during propagation of action potential. Above studies with pr-OCT were performed without scanning because scanning introduced phase noise, and the desired signal was buried under noise for the signal to noise ratio of 25~30 dB. However, spectral domain OCT was used to capture 3D volumetric intensity images during the neural activity in in vitro seizure mouse model after a period of baseline data. The average intensity of the hippocampal brain slice decreased by 10~18% from baseline during neural activity. Although intensity can separate neural activity from non-neural activity with 97.27% specificity and 97.60% sensitivity, it varies from experiment to experiment. Attenuation coefficient (μ), which quantifies how strongly a sample scatters and absorbs light is a constant for a sample, can solve the problem. During neural activities, there was a 10~15% decrease of μ. For both intensity and μ based method, there was a spatial correlation between optical changes and gold standard electrophysiology. Finally, quantified OCT intensity detected a localized action potential from CA1 of the hippocampal brain slice during ripple activation and -1% intensity threshold separated activity from non-activity.
Download or read book Functional Optical Coherence Tomography written by Utku Baran and published by . This book was released on 2016 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a revolutionary imaging technique commonly used in ophthalmology, and on its way to become a major tool in clinical dermatology and neuroscience. In this thesis, the non-invasive imaging capabilities of functional OCT are demonstrated in label-free detection of high-resolution, three-dimensional structural and microvascular features of in vivo human skin and mouse cerebral cortex, with various conditions. Moreover, new label-free methods for tissue injury mapping (TIM) and OCT-based lymphangiography (OLAG) with a clinical prospect are proposed. Based on the results, functional OCT is promising to become an indispensable, yet cost effective tool to monitor changes in tissue morphology and hemodynamics for diagnosis of various diseases or for following pharmacological interventions.
Download or read book Optical Coherence Tomography written by Wolfgang Drexler and published by Springer Science & Business Media. This book was released on 2008-12-10 with total page 1346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is emerging as a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue. This book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from biomedical and clinical perspectives. The chapters are written by leading research groups, in a style comprehensible to a broad audience.
Download or read book Emerging Imaging Technologies in Medicine written by Mark A. Anastasio and published by CRC Press. This book was released on 2012-12-06 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the discovery of x-rays in 1895 through the emergence of computed tomography (CT) in the 1970s and magnetic resonance imaging (MRI) in the 1980s, non-invasive imaging has revolutionized the practice of medicine. While these technologies have thoroughly penetrated clinical practice, scientists continue to develop novel approaches that promise to push imaging into entirely new clinical realms, while addressing the issues of dose, sensitivity, or specificity that limit existing imaging approaches. Emerging Imaging Technologies in Medicine surveys a number of emerging technologies that have the promise to find routine clinical use in the near- (less than five years), mid- (five to ten years) and long-term (more than ten years) time frames. Each chapter provides a detailed discussion of the associated physics and technology, and addresses improvements in terms of dose, sensitivity, and specificity, which are limitations of current imaging approaches. In particular, the book focuses on modalities with clinical potential rather than those likely to have an impact mainly in preclinical animal imaging. The last ten years have been a period of fervent creativity and progress in imaging technology, with improvements in computational power, nanofabrication, and laser and detector technology leading to major new developments in phase-contrast imaging, photoacoustic imaging, and optical imaging.
Download or read book Neuroimmune Pharmacology written by Tsuneya Ikezu and published by Springer. This book was released on 2016-12-22 with total page 1045 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Neuroimmune Pharmacology bridges the disciplines of neuroscience, immunology and pharmacology from the molecular to clinical levels with particular thought made to engage new research directives and clinical modalities. Bringing together the foremost field authorities from around the world, Neuroimmune Pharmacology will serve as an invaluable resource for the basic and applied scientists of the current decade and beyond.
Download or read book High Resolution Imaging in Microscopy and Ophthalmology written by Josef F. Bille and published by Springer. This book was released on 2019-08-13 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book provides a comprehensive overview of the application of the newest laser and microscope/ophthalmoscope technology in the field of high resolution imaging in microscopy and ophthalmology. Starting by describing High-Resolution 3D Light Microscopy with STED and RESOLFT, the book goes on to cover retinal and anterior segment imaging and image-guided treatment and also discusses the development of adaptive optics in vision science and ophthalmology. Using an interdisciplinary approach, the reader will learn about the latest developments and most up to date technology in the field and how these translate to a medical setting. High Resolution Imaging in Microscopy and Ophthalmology – New Frontiers in Biomedical Optics has been written by leading experts in the field and offers insights on engineering, biology, and medicine, thus being a valuable addition for scientists, engineers, and clinicians with technical and medical interest who would like to understand the equipment, the applications and the medical/biological background. Lastly, this book is dedicated to the memory of Dr. Gerhard Zinser, co-founder of Heidelberg Engineering GmbH, a scientist, a husband, a brother, a colleague, and a friend.
Download or read book Imaging in Dermatology written by Michael R. Hamblin and published by Academic Press. This book was released on 2016-07-29 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imaging in Dermatology covers a large number of topics in dermatological imaging, the use of lasers in dermatology studies, and the implications of using these technologies in research. Written by the experts working in these exciting fields, the book explicitly addresses not only current applications of nanotechnology, but also discusses future trends of these ever-growing and rapidly changing fields, providing clinicians and researchers with a clear understanding of the advantages and challenges of laser and imaging technologies in skin medicine today, along with the cellular and molecular effects of these technologies. Outlines the fundamentals of imaging and lasers for dermatology in clinical and research settings Provides knowledge of current and future applications of dermatological imaging and lasers Coherently structured book written by the experts working in the fields covered
Download or read book OCT Atlas written by Nagahisa Yoshimura and published by Springer. This book was released on 2014-06-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: OCT provided a great advantage over other diagnostic modalities, as it could noninvasively provide tomographic images of the retina of a living eye. As a result, a number of new findings in retinal diseases were made using the time-domain OCT. OCT has now become an essential medical equipment OCT has now become an essential medical equipment in ophthalmic care and quality textbooks describing the functionality of OCT are very important in the education of young ophthalmologists and eye care personnel. In this book are chosen high quality OCT images of rather common diseases as well as images of several rare diseases.
Download or read book OCT and Imaging in Central Nervous System Diseases written by and published by . This book was released on 2020 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of OCT and Imaging in Central Nervous System Diseases offers updated state-of-the-art advances using optical coherence tomography (OCT) regrading neuronal loss within the retina. Detailed information on the OCT imaging and interpretation is provided for the evaluation of disease progression in numerous neurodegenerative disorders and as a biological marker of neuroaxonal injury. Covering disorders like multiple sclerosis, Parkinson's disease, Alzheimer's disease, intracranial hypertension, Friedreich's ataxia, schizophrenia, hereditary optic neuropathies, glaucoma, and amblyopia, readers will given insights into effects on the retina and the and optic nerve. Individual chapters are also devoted to OCT technique, new OCT technology in neuro-ophthalmology, OCT and pharmacological treatment, and the use of OCT in animal models. Similar to the first edition, this book is an excellent and richly illustrated reference for diagnosis of many retinal diseases and monitoring of surgical and medical treatment. OCT allows to study vision from of the retina to the optic tracts. Retinal axons in the retinal nerve fiber layer (RNFL) are non-myelinated until they penetrate the lamina cribrosa. Hence, the RNFL is an ideal structure for visualization of any process of neurodegeneration, neuroprotection, or regeneration. By documenting the ability of OCT to provide key information on CNS diseases, this book illustrates convincingly that the eye is indeed the "window to the brain".
Download or read book Optics Letters written by and published by . This book was released on 2004 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book OCT Angiography in Retinal and Macular Diseases written by F. Bandello and published by Karger Medical and Scientific Publishers. This book was released on 2016-03-21 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: In only a short period of time, the innovative procedure of OCT angiography has become an essential macula imaging technique. Now that it is routinely used in clinical practice, the investigation of retinal and choroidal circulation is non-invasive, which significantly changes the professional’s approach to patients. In this volume, retina specialists and renowned experts share their experience with OCT angiography. They have included numerous color images and presented current ideas to form a base for further research and discussion. This book provides retina specialists, ophthalmologists, and researchers with a first glance at original research and clinical reports on this new methodology.
Download or read book Angiogenesis Lymphangiogenesis and Clinical Implications written by G. Marone and published by Karger Medical and Scientific Publishers. This book was released on 2013-10-21 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Angiogenesis, the formation of new blood vessels, is fundamental for physiological processes such as embryonic and postnatal development, wound repair, and reproductive functions. Angiogenesis plays a major role in tumor growth and in several autoimmune and allergic disorders. Lymphangiogenesis, the formation of new lymphatic vessels, is also important for tumor growth, the formation of metastasis, and chronic inflammatory diseases. Judah Folkman, a pioneer in the study of angiogenesis, first proposed that macrophages and mast cells could be a relevant source of angiogenic factors. Since then, much effort has gone into the elucidation of the role of immune cells in the modulation of angiogenesis and lymphangiogenesis. There is now compelling evidence that several components of the innate and adaptive immune system are implicated in inflammatory and neoplastic angiogenesis and lymphangiogenesis. Articles in this volume deal with the emerging, intriguing possibility that immune cells are both a source and a target of angiogenic and lymphangiogenic factors. Therefore, cells of the immune system might play a role in inflammatory and neoplastic angiogenesis/lymphangiogenesis through the expression of several angiogenic factors and their receptors and co-receptors. The important new findings in this volume will be of special interest to vascular biologists, basic and clinical immunologists, oncologists and to specialists in allergic and immune disorders.
Download or read book Quantitative Phase Imaging of Cells and Tissues written by Gabriel Popescu and published by McGraw Hill Professional. This book was released on 2011-03-14 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cutting-edge quantitative phase imaging techniques and their applications Filled with unique, full-color images taken by advanced quantitative phase imaging (QPI), Quantitative Phase Imaging of Cells and Tissues thoroughly explores this innovative technology and its biomedical applications. An introductory background on optical imaging and traditional optical microscopy is included to illustrate concept development. The book explains how various visualization modalities can be obtained by numerical calculations. This authoritative resource reveals how to take full advantage of the unprecedented capabilities of QPI, such as rendering scattering properties of minute subcellular structures and nanoscale fluctuations in live cells. Coverage includes: Groundwork Spatiotemporal field correlations Image characteristics Light microscopy Holography Point scanning QPI methods Principles of full-field QPI Off-axis full-field methods Phase-shifting techniques Common-path methods White light techniques Fourier transform light scattering (FTLS) Current trends in QPI
