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 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 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 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 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 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 Medical Imaging Systems written by Andreas Maier and published by Springer. This book was released on 2018-08-02 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book gives a complete and comprehensive introduction to the fields of medical imaging systems, as designed for a broad range of applications. The authors of the book first explain the foundations of system theory and image processing, before highlighting several modalities in a dedicated chapter. The initial focus is on modalities that are closely related to traditional camera systems such as endoscopy and microscopy. This is followed by more complex image formation processes: magnetic resonance imaging, X-ray projection imaging, computed tomography, X-ray phase-contrast imaging, nuclear imaging, ultrasound, and optical coherence tomography.
Download or read book Optical Measurements of Neural Activity Using Spectral domain Optical Coherence Tomography written by Aarthi Sivaprakasam and published by . This book was released on 2008 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Optical Coherence Tomography in Age Related Macular Degeneration written by Gabriel Coscas and published by Springer Science & Business Media. This book was released on 2009-07-25 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid or even dramatic progress has been made in the field of AMD over recent years, leading to a constant revision of basic concepts. A wide range of fundus imaging modalities are now available, and this book explains the respective value of each technique. The information provided by OCT is presented logically by comparison with plain films, autofluorescence, fluorescein angiography, or indocyanine green angiography. Meticulous biomicroscopic examination of macular changes and the essential value of fluorescein angiography for the detection of anatomical alterations of the macula and for precise evaluation of lesions and their course by indocyanine green angiography have naturally led the author Gabriel Coscas to analyze the new data provided by OCT.
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 Optical Coherence Tomography in Multiple Sclerosis written by Axel Petzold and published by Springer. This book was released on 2018-02-21 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a clinical context to optical coherence tomography (OCT) findings, while considering the differential diagnosis and providing patient management guidance. Relevant anatomical and technical aspects are discussed, followed by a pragmatic illustration of the use of OCT for the clinical spectrum of multiple sclerosis and optic neuritis, and finishing with information on monitoring ocular side effects of recently approved disease-modifying treatments in multiple sclerosis. Optical Coherence Tomography in Multiple Sclerosis: Clinical Applications is aimed at clinical neurologists working with patients suffering from MS and general neurologists who see patients with visual symptoms in their daily practice. Ophthalmologists sharing clinical responsibilities with neurologists for patients under disease-modifying treatments will also find the book of interest.
Download or read book Biochemical Sensors In 2 Volumes written by Huangxian Ju and published by World Scientific. This book was released on 2021-06-08 with total page 997 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the full scope of biochemical sensors and offers a survey of the principles, design and applications of the most popular types of biosensing devices. It is presented in 19 chapters, written by 20 distinguished scientists as well as their co-workers. The topics include the design of signal transducers, signal tags and signal amplification strategies, the structure of biosensing interfaces with new biorecognition elements such as aptamers and DNAzymes, and different newly emerging nanomaterials such as Au nanoclusters, carbon nitride, silicon, upconversion nanoparticles and two-dimensional materials, and the applications in wearable detections, biofuel cells, biomarker analyses, bioimaging, single cell analysis and in vivo sensing.By discussing recent advances, it is hoped this book will bridge the common gap between research literature and standard textbooks. Research into biochemical sensors and their biomedical applications is proceeding in a number of exciting directions, as reflected by the content. This book is published in honor of the 90th birthday of Professor Shaojun Dong, who performed many pioneering studies on modified electrodes and biochemical sensors.
Download or read book Optical Coherence Tomography in Neurologic Diseases written by Peter A. Calabresi and published by Cambridge University Press. This book was released on 2015-05-14 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) provides tissue morphology imagery at much higher resolution than other imaging modalities such as MRI or ultrasound, and the machines are comparatively cheaper. It is an easy technique to perform; is non-ionizing, and therefore safe. These benefits are driving a rapid transformation of OCT, from its principal application as a research tool, into an extension of the 'neurological examination' in routine office practice. Originally used in assessing the severity of tissue damage and prognosis of multiple sclerosis and various neuro-ophthalmic conditions, OCT is increasingly used in other neurological disorders such as Parkinson's disease, ALS, and Alzheimer's disease. This book is the first comprehensive review of the use of OCT in neurological diseases. The coverage includes a description of the technique and its utilization in a variety of neurologic conditions. Essential reading for neurologists, neuro-ophthalmologists, and neuroradiologists wanting an introductory account of the clinical applications of OCT.
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 Optical Coherence Tomography of Ocular Diseases written by Joel S. Schuman and published by CRC Press. This book was released on 2024-06-01 with total page 1093 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most comprehensive text and definitive guide for nearly 30 years about optical coherence tomography (OCT) imaging in ophthalmology, Optical Coherence Tomography of Ocular Diseases, Fourth Edition covers a range of subjects, from principles and operation techniques to clinical interpretation and the latest innovations in OCT. Written by the pioneers of OCT technologies and the world-renowned OCT researchers Drs. Joel S. Schuman, James G. Fujimoto, Jay S. Duker, Hiroshi Ishikawa, and Gadi Wollstein, Optical Coherence Tomography of Ocular Diseases, Fourth Edition is an essential text for imaging technology. OCT now occupies a dominant role as a diagnostic tool for retinal conditions and glaucoma. At the same time, the technology continues to show potential for emerging clinical and research applications across all the ophthalmological subspecialties. To reflect these rapid advances, this new edition of Optical Coherence Tomography of Ocular Diseases features a complete and thorough revision of the existing text as well as the addition of cutting-edge content to bring this classic resource completely up to date. New content in the Fourth Edition includes: • OCT angiography • Swept-source OCT • OCT in multimodal imaging • Clinical utility of OCT in glaucoma prediction and progression detection • OCT for neuro-ophthalmology Optical Coherence Tomography of Ocular Diseases, Fourth Edition is the one and only book needed by practitioners who use OCT for clinical eye care.
Download or read book Pathologic Myopia written by Richard F. Spaide and published by Springer Nature. This book was released on 2021-07-28 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pathologic Myopia is a major cause of severe vision loss worldwide. The mechanisms for vision loss include cataract, glaucoma, retinal detachment, and above all, myopic maculopathy within the posterior staphyloma. The first edition of Pathologic Myopia is one of the only current books to specifically address this disease and discusses recent developments in imaging technologies and various approaches to treatments, such as laser photocoagulation, photodynamic therapy, pharmaco-therapeutic injections in the vitreous, and surgery. This new edition is a timely update to the standard reference in the field, with new chapters on advanced refractive error correction, genetics, developing a classification system, and special surgical approaches for pathologic myopia. Complete with even more high-quality color images and informative tables, this book is written and edited by leaders in the field and is geared towards ophthalmologists, including residents and fellows in training, glaucoma and cataract specialists, and vitreoretinal macula experts.
