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 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 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 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 The Fovea written by Andreas Bringmann and published by Academic Press. This book was released on 2021-08-28 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fovea: Structure, Function, Development, and Disease summarizes the current biological knowledge regarding the two types of the vertebrate fovea (and its main structural elements, the Müller cells). This information is then used to explain different aspects of human vision, foveal development, and macular disorders. Sections give an overview of the retinal structure and the different types of retinal glia, survey the structure and function of the primate and non-mammalian fovea types, discuss foveal development—with a focus on the human fovea, cover the roles of Müller cells and astrocytes in the pathogenesis and regeneration of various human macular disorders are described. Using a translational approach, this reference is a valuable text for scientists, clinicians and physicians interested in the fovea. Readers will gain a new understanding of the cellular basics of the fovea, which is the most important part of the eye. Adopts a translational approach, summarizing the biological knowledge regarding the structure and function of the fovea, the roles of Müller cells in mediating the structural integrity, and function of the fovea Provides overviews of both basic types of the vertebrate fovea, countering the popular belief that there is only one type of the vertebrate fovea, the human fovea Thoroughly shows the mechanisms involved in the development of the fovea that explain the rapid improvement of visual acuity in newborns Explains pathological changes in the foveal structure and function with evaluation pointing toward possible prevention and/or cure
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 Foundations of Vision written by Brian A. Wandell and published by Sinauer Associates, Incorporated. This book was released on 1995 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed for students, scientists and engineers interested in learning about the core ideas of vision science, this volume brings together the broad range of data and theory accumulated in this field.
Download or read book The Neural Basis of Early Vision written by A. Kaneko and published by Springer Science & Business Media. This book was released on 2013-03-13 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Researchers in recent decades have elucidated signal transduction in the retina and the function of the visual cortex. The highly flexible nature of neural circuits in the visual cortex especially during the critical period has been an interesting subject for studying neural plasticity and development. Recent advances in the visual neurosciences of the vertebrate retina and the visual cortex were discussed during the 12th Keio International Symposium for Life Science and Medicine, meeting jointly with Vision Forum 2002. Contributions to the symposium collected in this volume reflect the convergence of physiological, cell biological, molecular, mathematical, and clinical approaches. The book covers topics ranging from phototransduction to visual information processing in the primary visual cortex, and includes clinical studies on hereditary night blindness, creating a valuable source of information for researchers and clinicians in the visual neurosciences.
Download or read book Journal of Rehabilitation R D written by and published by . This book was released on 2004 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Spatiotemporal Receptive Field Properties of Rat Retinal Ganglion Cells written by Walter Ferdinand Heine and published by . This book was released on 2011 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The function of the retina is to encode relevant features of the visual world in the form of neural spike trains. These are transmitted to higher visual centers in the brain by retinal ganglion cells (RGCs), which form the neural output of the retina. Little is known about the receptive field properties of these cells in the rat. In vivo recording techniques were used to record from RGC axons while visual stimuli were displayed on a cathode ray tube. Rats have a wide visual field and large receptive fields. In order to capture the majority of the visual field, the monitor was placed in close proximity to the eye of the animal. Visual stimulus patterns such as luminance gratings appear distorted at a close viewing distance. We therefore simulated a spherical screen with the eye at its center. Cells shared many properties with those of other species but also exhibited some notable differences. Some cells exhibited the characteristic linear and nonlinear spatial summation of cat X and Y cells and were therefore labeled as X and Y-like. More rarely encountered cell types included the suppressed by contrast and ON-OFF surround cells. In contrast to their counterparts in the cat, X and Y-like cells in the rat had similar receptive field sizes. In the temporal domain, X-like cells exhibited sustained response dynamics to square wave modulated spots. Y-like cells, on the other hand, displayed both sustained and transient response dynamics. Both cell types responded to full field stimuli by reducing their gain at low temporal frequencies and exhibiting a resonance at higher frequencies. These results question the commonly assigned roles of X-like cells in high acuity vision and Y-like cells in motion detection. Anatomical data on their morphological properties and projection pattern will provide additional insight into their possible functional roles. Photodynamic staining provides a means of targeting cells for electrophysiological recordings that display specific morphological and projection patterns. We found enhanced photodynamic staining in media supplemented with oxygen or hydrogen peroxide. This information will aid future experiments correlating the anatomical and electrophysiological properties of RGC types.
Download or read book Advances in Natural Computation written by Licheng Jiao and published by Springer. This book was released on 2006-09-28 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is volume I of the proceedings of the Second International Conference on Natural Computation, ICNC 2006. After a demanding review process 168 carefully revised full papers and 86 revised short papers were selected from 1915 submissions for presentation in two volumes. This first volume includes 130 papers related to artificial neural networks, natural neural systems and cognitive science, neural network applications, as well as evolutionary computation: theory and algorithms.
Download or read book Annual Report National Eye Institute written by National Eye Institute and published by . This book was released on 1987 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Attention in Foveal and Peripheral Vision written by Lisa Marie Isenberg and published by . This book was released on 1992 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1979 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Visual Perception written by Lothar Spillmann and published by Elsevier. This book was released on 2012-12-02 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an interdisciplinary overview of the main facts and theories that guide contemporary research on visual perception. While the chapters cover virtually all areas of visual science, from philosophical foundations to computational algorithms, and from photoreceptor processes to neuronal networks, no attempt has been made to provide an exhaustive treatment of these topics. Rather, researchers from such diverse disciplines as psychology, neurophysiology, anatomy, and clinical vision sciences have worked together to review some of the most important correlations between perceptual phenomena and the underlying neurophysiological processes and mechanisms. The book is thus intended to serve as an advanced text for graduate students and as a guide for all vision researchers to understanding current progress outside their specialized fields of interest.ï Examines parallel processing of visual informationï Discusses links between physiologically-measured receptive fields and psychophysically-measured perceptive fieldsï Presents a spatial sampling by the retina and cortical modulesï Covers signal transduction and the sites of adaptationï Describes a single-cell analysis of attentionï Discusses computational models of vision
Download or read book The First Steps in Seeing written by Robert W. Rodieck and published by Sinauer Associates Incorporated. This book was released on 1998-01-01 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: The First Steps in Seeing is about the eyes, and how they capture an image and convert it to the neural messages that ultimately result in visual experience. A full appreciation of how the eyes work is rooted in diverse areas of science-optics; biochemistry and photochemistry; molecular biology, cell biology, neurobiology, and evolutionary biology; psychology and psychophysics. The findings related to vision from any one of these fields are not difficult to understand in themselves, but, in order to be clear and precise, each discipline has developed its own set of words and conceptual relations-in effect, its own language-and for those wanting a broad introduction to vision these separate languages can present more of an impediment to understanding than an aid. However, what lies beneath these words usually has a beautiful simplicity, and it is the aim of The First Steps in Seeing to describe how we see in a manner that is understandable to all. In this book, the use of technical terms is restricted, and several hundred full-color illustrations ensure that the terms that are used are associated with a picture, icon, or graph that visually expresses their meaning. Experimental findings have been recast in terms of the natural world whenever possible, and broad themes bring together lines of thought that are often treated separately. Fourteen main chapters form a "thread" that tells the main scientific story and can be read without specialized knowedge or reliance on other sources. This thread is linked to fourteen discussions which explore certain crucial topics in greater depth. Notes link the material presented in the thread and in the special topics discussions to important review articles and seminal research papers. The First Steps in Seeing is an innovative, authoritative work that belongs in the library of anyone with an interest in visual perception.
Download or read book Prenatal Development of Regional Specialization in the Ganglion Cell Layer of the Retina written by Barry Donald Obodov Lia and published by . This book was released on 1989 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
