Download or read book Visual Acuity and Its Dependence Upon Receptor Density and Retinal Ganglion Cell Receptive Field Overlap written by Myron L. Wolbarsht and published by . This book was released on 1981 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The organization of the retina was investigated with regard to visual acuity. In particular, the receptive fields of the ganglion cells were analyzed and described in terms of, primarily, their anatomical relations to each other, i.e., receptor spacing and secondly, the neural organization. In a typical eye (cat) the sensitivity to angular separation on the basis of anatomical makeup has an upper limit of 8 cycles per degree for acuity. On the other hand, it is predicted that, for neural processing of overlapping ganglion cell receptive fields in the retina, the behavioral response should be at least twice as good, i.e., approximately 16 cycles per degree. The different methods of analyzing receptive fields compare the sensitivity of the receptors with a static stimulus (sensitivity profile and Ricco field - area x intensity - test), and displacement sensitivity (the response to a small stimulus spot switched between the two positions just touching each other). Present data, which indicates that in the area of high sensitivity in the cat retina at least 15 receptive field centers must overlap, leads to the conclusion that the retinal visual acuity is not limited by the receptive field size, but rather displacement sensitivity and the processing of the information by higher visual centers.
Download or read book Dependence of Foveal Visual Acuity on the Size of the Receptive Fields of Retinal Ganglion Cells written by Myron L. Wolbarsht and published by . This book was released on 1979 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Visual acuity is analyzed in terms of the retinal ganglion cell response to different stimuluses on the receptor matrix. The antagonism between the central and peripheral responses of the ganglion cell receptive field is shown to effect both the sensitivity profile and the Ricco field (Area X Intensity) response. The difficulties with each method of analyzing the receptive field are discussed and an experimental protocol is formulated which derives information by comparisons between the different approaches. Data is presented to show that the ganglion cell receptive fields comparison many receptors even in the portion of the retina where the visual acuity is highest. The experimental data for a similarity between ganglion cell receptive fields in the central and peripheral portions of the retina in the cat is given and compared with similar data for the monkey. (Author).
Download or read book Webvision written by Helga Kolb and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parallel Processing in the Visual System written by Jonathan Stone and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the mid-sixties, John Robson and Christina Enroth-Cugell, without realizing what they were doing, set off a virtual revolution in the study of the visual system. They were trying to apply the methods of linear systems analysis (which were already being used to describe the optics of the eye and the psychophysical performance of the human visual system) to the properties of retinal ganglion cells in the cat. Their idea was to stimulate the retina with patterns of stripes and to look at the way that the signals from the center and the antagonistic surround of the respective field of each ganglion cell (first described by Stephen Kuffier) interact to generate the cell's responses. Many of the ganglion cells behaved themselves very nicely and John and Christina got into the habit (they now say) of calling them I (interesting) cells. However. to their annoyance, the majority of neurons they recorded had nasty, nonlinear properties that couldn't be predicted on the basis of simple summ4tion of light within the center and the surround. These uncoop erative ganglion cells, which Enroth-Cugell and Robson at first called D (dull) cells, produced transient bursts of impulses every time the distribution of light falling on the receptive field was changed, even if the total light flux was unaltered.
Download or read book Molecular and Cellular Basis of Visual Acuity written by S.R. Hilfer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Seventh Symposium on Ocular and Visual Development was held in October, 1982. The aim of the meeting was to develop a broad perspective on visual acuity. The subject was discussed initially in terms of molecular events of photoreception, and the metabolism of the photoreceptor ele ments. Subsequent papers presented the development and complexity of the neurocircuitry and transmitter systems in the retina that process the visual information prior to transfer to the brain. The meeting concluded with a series of papers on behavioral and physiological methods of mea surement of visual acuity in humans, particularly young children. This volume arose from the papers presented at the meeting. We feel that the juxtaposition of research of broadly differing methodologies will be stim ulating, rather than daunting, and will generate an enhanced understand ing of this complex subject. We are indebted to our colleagues: Dr. M. Mote from Temple University, and Drs. J. Siegfried, P. Dayhaw-Barker, and L. Press from the Pennsylvania College of Optometry for their expertise and assistance in the organization of the meeting; to the speakers for their presentations and contributions to this volume; and to the reviewers of the manuscripts for their helpful comments. This symposium could not have been held without the generous support of the Temple University College of Arts and Sciences and the Pennsyl vania College of Optometry. We also thank Merck, Sharp and Dohme, Inc. for their donation.
Download or read book Visual Acuity and Retinal Organization written by Myron L. Wolbarsht and published by . This book was released on 1978 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Visual acuity depends upon three components: the image upon the retina, the dissection of this image by the retina, and the processing of the signals from the receptors by the visual system. The limitations upon the image on the retina imposed by the optical system of the eye and the wave nature of light are summarized. The receptor mosaic is related to the retinal image by point spread functions for both monochromatic and white light. The image on the retina and receptor mosaic are reviewed as the accepted ultimate limitations on visual acuity. The neural organization of the retina as epitomized in the ganglion cell receptive field is introduced as a mechanism for extending the limits imposed by the optics and receptors. Two types of retinal organization--point-to-point and converging--are developed. The point-to-point representation is shown inadequate from the standpoint of retinal anatomy. The performance of eagle and hawk eyes with ganglion cell-to-receptor ratios of 1:4 and 1:10 are used to illustrate possible mechanisms operating in the human fovea. Suggestions are made for future experimental investigations to choose between alternative models. (Author).
Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1982 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Retinal Development written by Evelyne Sernagor and published by Cambridge University Press. This book was released on 2012-11-29 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This advanced text, first published in 2006, takes a developmental approach to the presentation of our understanding of how vertebrates construct a retina. Written by experts in the field, each of the seventeen chapters covers a specific step in the process, focusing on the underlying molecular, cellular, and physiological mechanisms. There is also a special section on emerging technologies, including genomics, zebrafish genetics, and stem cell biology that are starting to yield important insights into retinal development. Primarily aimed at professionals, both biologists and clinicians working with the retina, this book provides a concise view of vertebrate retinal development. Since the retina is 'an approachable part of the brain', this book will also be attractive to all neuroscientists interested in development, as processes required to build this exquisitely organized system are ultimately relevant to all other parts of the central nervous system.
Download or read book Anatomy Ocular physiology Biochemistry and genetics Pathology Microbiology Immunology Growth and senescence Optics Therapeutics Lasers and instrument technology Basic biostatistical and epidemiological terms written by Louise Bye and published by OUP Oxford. This book was released on 2013-05-23 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: An indispensable and fully comprehensive textbook, this covers the basic sciences in ophthalmology and is the only book you need to pass the FRCOphth Part 1 exam.
Download or read book Duplicity Theory of Vision written by Bjørn Stabell and published by Cambridge University Press. This book was released on 2009-08-13 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book chronicles the development of three classic theories within vision research, from the 17th century to today, focusing on duplicity theory.
Download or read book Understanding Vision written by Li Zhaoping and published by Oxford University Press, USA. This book was released on 2014 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vision science has grown hugely in the past decades, but there have been few books showing readers how to adopt a computional approach to understanding visual perception, along with the underlying mechanisms in the brain. This book explains the computational principles and models of biological visual processing, and in particular, primate vision.
Download or read book The Visual Neurosciences written by John Simon Werner and published by MIT Press. This book was released on 2004 with total page 975 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference book for visual science.
Download or read book Pediatric Neuro Ophthalmology written by Michael C. Brodsky and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pediatric Neuroophthalmology details the diagnostic criteria, current concepts of pathogenesis, neuroradiological correlates, and clinical management of a large group of neuroophthalmic disorders that present in childhood. Surprisingly distinct from neuroophthalmic disorders afflicting adults, this set of diseases falls between the cracks of most ophthalmology training, and thus, warrants a practical, clinical guide for the practitioner in ophthalmology - the neuroophthalmologist, pediatric ophthalmologist, general ophthalmologist - as well as neurologists and for residents. The authors, leading pediatric ophthalmologists, have taken this difficult subject matter and developed an accessible, user-friendly manual with a detailed approach to the recognition, differential diagnosis, and management of pediatric neuroophthalmologic disorders.
Download or read book Development and Organization of the Retina written by Leo M. Chalupa and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development and Organization of the Retina offers an invaluable survey of contemporary research issues and methods dealing with the retina and retinal projections. The book's 19 chapters report on investigations into two areas: research into the organization of the mature retina and work on developmental issues. A sampling of chapter topics includes -- embryonic patterning of cone subtypes in the mammalian retina -- synaptic transmission between retinal neurons -- scaling the retina, macro and micro -- retinal ganglion cell axonal transport, and more.
Download or read book Machine Vision Handbook written by Bruce G. Batchelor and published by Springer. This book was released on 2012-02-14 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The automation of visual inspection is becoming more and more important in modern industry as a consistent, reliable means of judging the quality of raw materials and manufactured goods . The Machine Vision Handbook equips the reader with the practical details required to engineer integrated mechanical-optical-electronic-software systems. Machine vision is first set in the context of basic information on light, natural vision, colour sensing and optics. The physical apparatus required for mechanized image capture – lenses, cameras, scanners and light sources – are discussed followed by detailed treatment of various image-processing methods including an introduction to the QT image processing system. QT is unique to this book, and provides an example of a practical machine vision system along with extensive libraries of useful commands, functions and images which can be implemented by the reader. The main text of the book is completed by studies of a wide variety of applications of machine vision in inspecting and handling different types of object.
Download or read book Connectome written by Sebastian Seung and published by HMH. This book was released on 2012-02-07 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: “Accessible, witty . . . an important new researcher, philosopher and popularizer of brain science . . . on par with cosmology’s Brian Greene and the late Carl Sagan” (The Plain Dealer). One of the Wall Street Journal’s 10 Best Nonfiction Books of the Year and a Publishers Weekly “Top Ten in Science” Title Every person is unique, but science has struggled to pinpoint where, precisely, that uniqueness resides. Our genome may determine our eye color and even aspects of our character. But our friendships, failures, and passions also shape who we are. The question is: How? Sebastian Seung is at the forefront of a revolution in neuroscience. He believes that our identity lies not in our genes, but in the connections between our brain cells—our particular wiring. Seung and a dedicated group of researchers are leading the effort to map these connections, neuron by neuron, synapse by synapse. It’s a monumental effort, but if they succeed, they will uncover the basis of personality, identity, intelligence, memory, and perhaps disorders such as autism and schizophrenia. Connectome is a mind-bending adventure story offering a daring scientific and technological vision for understanding what makes us who we are, as individuals and as a species. “This is complicated stuff, and it is a testament to Dr. Seung’s remarkable clarity of exposition that the reader is swept along with his enthusiasm, as he moves from the basics of neuroscience out to the farthest regions of the hypothetical, sketching out a spectacularly illustrated giant map of the universe of man.” —TheNew York Times “An elegant primer on what’s known about how the brain is organized and how it grows, wires its neurons, perceives its environment, modifies or repairs itself, and stores information. Seung is a clear, lively writer who chooses vivid examples.” —TheWashington Post
Download or read book Handbook of Geometric Computing written by Eduardo Bayro Corrochano and published by Springer Science & Business Media. This book was released on 2005-12-06 with total page 773 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many computer scientists, engineers, applied mathematicians, and physicists use geometry theory and geometric computing methods in the design of perception-action systems, intelligent autonomous systems, and man-machine interfaces. This handbook brings together the most recent advances in the application of geometric computing for building such systems, with contributions from leading experts in the important fields of neuroscience, neural networks, image processing, pattern recognition, computer vision, uncertainty in geometric computations, conformal computational geometry, computer graphics and visualization, medical imagery, geometry and robotics, and reaching and motion planning. For the first time, the various methods are presented in a comprehensive, unified manner. This handbook is highly recommended for postgraduate students and researchers working on applications such as automated learning; geometric and fuzzy reasoning; human-like artificial vision; tele-operation; space maneuvering; haptics; rescue robots; man-machine interfaces; tele-immersion; computer- and robotics-aided neurosurgery or orthopedics; the assembly and design of humanoids; and systems for metalevel reasoning.
