Download or read book Temporal Contrast Adaptation in Identified Types of Retinal Ganglion Cells written by Divya Chander and published by . This book was released on 2002 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Encoding Visual Features by Parallel Ganglion Cell Initiated Pathways in the Healthy Diseased and Artificial Retina written by Béla Völgyi and published by Frontiers Media SA. This book was released on 2019-10-16 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photons are sensed by retinal photoreceptors whose matrix-like distribution underlies the transformation of illumination patterns of the visual scene into photoreceptor activity patterns in a visuotopic fashion. Activity of neighboring photoreceptors then are compared by secondary bipolar cells to decipher information regarding luminosity- and color-contrast. Bipolar cells achieve this by comparing signals received directly from their center receptive field with those come from spatially offset surrounding receptive field areas mediated by inhibitory, sign-inverting horizontal cells. This information is ultimately sent to retinal ganglion cells, the output neurons of the retina. In addition to the excitatory bipolar cell inputs, spatial and temporal features of ganglion cell activation are robustly modified by inner retinal amacrine cells through inhibitory chemical and/or excitatory electrical synaptic inputs. Ganglion cells sample various bipolar cell subtypes in their dendritic field and utilize collected inputs to generate a spike output code on luminosity-contrast, color-contrast, object motion, background motion, motion direction, changes in background illumination in a subtype specific manner. Ganglion cells in each subtype cover the retinal surface economically, thus collective information across the population provide a feature pattern and through time a feature movie to the brain. Some of these movies are utilized for image perception, whereas others are sent to accessory visual brain centers to control eye-movement, pupil contraction or circadian entrainment. A large body of information has been revealed in the past decade regarding this field, however much of the details still remain unknown or even enigmatic, including: (i) the precise description of neural circuits that serve each ganglion cell subtype to generate a specific feature movie; (ii) the estimation of the number of various ganglion cell subtypes that partake in image forming and non-image forming signaling towards the brain; (iii) the description of changes in the inputs, morphology and signaling of retinal ganglion cells when the tissue is under stress or undergoes disease related degenerative processes; (iv) the comparison of ganglion cell classes with those of the human retina and finally, (v) the practical use of all the above information to establish retina inspired visual algorithms to suit computer, drone and/or robotic vision. Therefore, research articles in this issue were collected to touch upon each of these topics and highlight recent advances of the related field.
Download or read book Contrast Sensitivity written by R. M. Shapley and published by . This book was released on 1993 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation The seventeen contributions present current research in visual signal processing, inthe retina and central pathways, and in the study of contrast sensitivity in humans.
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 Local Circuits in the Retina written by Solange Stéphanie Pezon Brown and published by . This book was released on 2001 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Linking the Computational Structure of Variance Adaptation to Biophysical Mechanisms written by Yusuf Ozuysal and published by Stanford University. This book was released on 2011 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neurons have a limited dynamic range. To more efficiently encode the large range of natural inputs, neural circuits adapt by dynamically changing their output range as a function of the input statistics. Variance adaptation provides an informative example of this process, whereby neurons change their response characteristics as a function of variance of their input. When their input distribution changes, sensory systems shift and scale their response curves to efficiently cover the new range of input values and they focus on different segments of the frequency spectrum, for example by choosing to average out the noise in a low signal-to-noise ratio environment by low-pass filtering their input and sacrificing resolution. In multiple sensory systems, adaptation to the variance of a sensory input changes the sensitivity, kinetics and average response over timescales ranging from
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 Temporal Properties of the Center Mechanism of Cat X Retinal Ganglion Cells written by Lisa Chang-An Diller and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Retina and its Disorders written by Joseph Besharse and published by Academic Press. This book was released on 2011-04-19 with total page 929 pages. Available in PDF, EPUB and Kindle. Book excerpt: This selection of articles from the Encyclopedia of the Eye covering retina, optics/optic nerve and comparative topics constitutes the first reference for scientists, post docs, and graduate students with an interest beyond standard textbook materials. It covers the full spectrum of research on the retina - from the basic biochemistry of how nerve cells are created to information on neurotransmitters, comparisons of the structure and neuroscience of peripheral vision systems in different species, and all the way through to injury repair and other clinical applications. - The first single volume to integrate comparative studies into a comprehensive resource on the neuroscience of the retina - Chapters are carefully selected from the Encyclopedia of the Eye by one of the world's leading vision researchers - The best researchers in the field provide their conclusions in the context of the latest experimental results
Download or read book Contrast Sensitivity written by Robert Shapley and published by MIT Press. This book was released on 1993 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: The seventeen contributions present current research in visual signal processing, in the retina and central pathways, and in the study of contrast sensitivity in humans. The seventeen contributions present current research in visual signal processing, in the retina and central pathways, and in the study of contrast sensitivity in humans.
Download or read book Sites and Mechanisms of Temporal Contrast Adaptation in the Salamander Retina written by Kerry Justin Kim and published by . This book was released on 2002 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neural Engineering written by Chris Eliasmith and published by MIT Press. This book was released on 2003 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: A synthesis of current approaches to adapting engineering tools to the study of neurobiological systems.
Download or read book Contrast Sensitization written by David B. Kastner and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptation provides a ubiquitous strategy for neural circuits to encode their inputs using their limited dynamic range within the variety of sensory environments that they encounter. However, because of the inherent timescale necessary to optimize the response properties of a cell to its environment, any form of adaptive plasticity can cause a neuron to fail to encode the stimulus when the environment changes. Many ganglion cells, the output neurons of the retina, adapt so as to lower their sensitivity in an environment of high contrast, but if the contrast subsequently decreases the cell will fall below threshold and fail to signal. I have found a distinct form of plasticity within the retina that acts in coordination with the process of adaptation. Cells using this new form of plasticity elevate their sensitivity after a transition to low contrast. This process, called sensitization, occurs in retinas from multiple species. Multielectrode recordings from sensitizing and adapting cells indicate that both populations encode the same visual signals. The complementary action of the two populations helps the retina encode its input over a broader range of signals and environmental changes, with one population continuing to respond when the other fails. The threshold placement of these two cell types further enhances their coordination because sensitizing cells maintain lower thresholds, while adapting cells maintain higher thresholds. Using a theoretical model, I was able to show that this behavior maximized the amount of information that the two populations can provide about their input. I have further studied the spatiotemporal region that controlled the sensitivity of a cell--the adaptive field. Just as retinal circuitry uses excitation and inhibition to form biphasic center-surround receptive fields, the retina can also use adaptation and sensitization to form biphasic adaptive fields in both the spatial and temporal domains. Since visual statistics are correlated across time and space, center-surround biphasic receptive fields more efficiently encode the input by subtracting a prediction of the stimulus so as to just encode the deviation from that prediction. Biphasic adaptive fields appear to perform an opposite function, transmitting a prediction of the stimulus at the transition of a stimulus environment to weaker signals. This assists in the encoding of an uncertain environment by storing features of a predictable input. A model indicates that sensitization within the adaptive field can be produced by adapting inhibition, a form of plasticity whose function was previously unknown. Using pharmacology, I confirmed this prediction, showing that GABAergic inhibition is necessary for sensitization. Using simultaneous intracellular recording from inhibitory amacrine cells and multielectrode recording from ganglion cells, I show that transmission from a single amacrine cell is sucient to cause sensitization. Using a novel approach to analyze a circuit, I quantitatively describe the changes in amacrine cell transmission that underlie sensitization thus elucidating how the retina performs this sophisticated computation.
Download or read book Maintained Discharge and Adaptation Properties of Rat Retinal Ganglion Cells written by Daniel Kenneth Freeman and published by . This book was released on 2009 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Visual information is relayed from the eye to the brain by retinal ganglion cells whose axons make up the optic nerve. An experimental system was developed to allow in vivo recordings of action potentials from rat retinal ganglion cell fibers in response to visual stimuli of interest. In the presence of a uniformly illuminated receptive field, ganglion cells fire an irregular pattern of action potentials referred to as the maintained discharge. We characterized the statistics of the maintained discharge using interval distributions and power spectral densities. While spike trains collected under ketaminexylazine anesthesia were generally stationary, spike trains under urethane anesthesia were unstable, producing slow, unpredictable, quasi-periodic fluctuations in firing rate. Under both anesthetic conditions, high frequency (28.9-41.4Hz) oscillations were present in the spike trains, as evidenced by multi-modal interspike interval distributions and a clear peak in the power spectral density. Oscillations were present in the dark, but at a slightly lower frequency, indicating that the oscillations were generated independent of light, but can be modulated by light level. An integrate-and-fire model with input current consisting of Gaussian noise plus a sinusoidal drive described the oscillations well. Next, the light adaptive properties of ganglion cells were studied. Ganglion cells are known to decrease their sensitivity in inverse proportion to the light input, but the contrast levels required to induce adaptation has been given little attention. This brings in to question the degree to which ganglion cells exhibit luminance adaptation as the eyes scan a typical natural scene. Using a probed-sinewave paradigm, we found that even low contrast (15%) stimuli can induce adaptation, yielding both increases and decreases of ganglion cell sensitivity relative to baseline. Ganglion cell firing rate does not appear to be the direct cause for the adaptation, as a given modulation depth can produce a large range of sensitivities. Adaptation is still seen when the frequency of the sinewave was increased from 0.25Hz to 1Hz, indicating the timescale of adaptation is in the range of
Download or read book The New Visual Neurosciences written by John S. Werner and published by MIT Press. This book was released on 2013-10-25 with total page 1693 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of contemporary research in the vision sciences, reflecting the rapid advances of recent years. Visual science is the model system for neuroscience, its findings relevant to all other areas. This essential reference to contemporary visual neuroscience covers the extraordinary range of the field today, from molecules and cell assemblies to systems and therapies. It provides a state-of-the art companion to the earlier book The Visual Neurosciences (MIT Press, 2003). This volume covers the dramatic advances made in the last decade, offering new topics, new authors, and new chapters. The New Visual Neurosciences assembles groundbreaking research, written by international authorities. Many of the 112 chapters treat seminal topics not included in the earlier book. These new topics include retinal feature detection; cortical connectomics; new approaches to mid-level vision and spatiotemporal perception; the latest understanding of how multimodal integration contributes to visual perception; new theoretical work on the role of neural oscillations in information processing; and new molecular and genetic techniques for understanding visual system development. An entirely new section covers invertebrate vision, reflecting the importance of this research in understanding fundamental principles of visual processing. Another new section treats translational visual neuroscience, covering recent progress in novel treatment modalities for optic nerve disorders, macular degeneration, and retinal cell replacement. The New Visual Neurosciences is an indispensable reference for students, teachers, researchers, clinicians, and anyone interested in contemporary neuroscience. Associate Editors Marie Burns, Joy Geng, Mark Goldman, James Handa, Andrew Ishida, George R. Mangun, Kimberley McAllister, Bruno Olshausen, Gregg Recanzone, Mandyam Srinivasan, W.Martin Usrey, Michael Webster, David Whitney Sections Retinal Mechanisms and Processes Organization of Visual Pathways Subcortical Processing Processing in Primary Visual Cortex Brightness and Color Pattern, Surface, and Shape Objects and Scenes Time, Motion, and Depth Eye Movements Cortical Mechanisms of Attention, Cognition, and Multimodal Integration Invertebrate Vision Theoretical Perspectives Molecular and Developmental Processes Translational Visual Neuroscience
Download or read book Encyclopedia of the Eye written by Joseph Besharse and published by Academic Press. This book was released on 2010-05-27 with total page 2352 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the first comprehensive reference for the eye, its support structures, diseases, and treatments, Encyclopedia of the Eye is an important resource for all visual scientists, ophthalmologists, and optometrists, as well as researchers in immunology, infectious disease, cell biology, neurobiology and related disciplines. This four-volume reference is unique in its coverage of information on all tissues important for vision, including the retina, cornea and lens. It also covers the physiological and pathophysiologic processes that affect all eye tissues. This Encyclopedia is invaluable for graduate students and postdoctoral fellows who are seeking an introduction to an area of eye research. Each chapter explains the basic concepts and provides references to relevant chapters within the Encyclopedia and more detailed articles across the wider research literature. The Encyclopedia is also particularly useful for visual scientists and practitioners who are researching a new area, seeking deeper understanding of important research articles in fields adjacent to their own, or reviewing a grant outside their immediate area of expertise. Written by experts at a level that permits students to grasp key elements of a specific subject Provides an entryway into the major features of current eye research No other source puts this much information, so well-indexed and with so many helpful full color figures and graphics, in the hands of the ophthalmic scientist
