The Organization of the Retina and Visual System
Donnell J. Creel Introduction One of the evolutionary characteristics of the mammalian visual system is the increase of binocular overlap of vision as eyes progress from being located on side of the head such as the guinea pig to the frontal position in Haplorrhine primates. Concomitantly as the proportion of temporal retina …
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1 Introduction “Nothing in biology makes sense except in the light of evolution” (1). Theodosius Dobzhansky’s insight is especially apposite in trying to comprehend the nature of our rod and cone photoreceptors, and the organization of our retina. Unless we understand how these cells and structures arose, through hundreds of millions of years of evolution, …
By Silke Haverkamp Glycine is a major inhibitory neurotransmitter in the mammalian central nervous system (CNS). Its receptors, the inhibitory glycine receptors (GlyRs), are ligand-gated chloride channels composed of ligand-binding α and β subunits (Betz and Laube, 2006; Lynch, 2009). In mature neurons, the activation of GlyRs allows for an influx of chloride ions …
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Helga Kolb When looking into someone’s eyes, we can easily see several structures: Fig. 1. View of the human eye A black-looking aperture, the pupil,that allows light to enter the eye (it appears dark because of the absorbing pigments in the retina). A colored circular muscle, the iris, which is beautifully pigmented giving us our …
By Gregory S. Hageman, Karen Gaehrs, Lincoln V. Johnson and Don Anderson 1. Introduction. Age-related macular degeneration (AMD), the leading cause of worldwide blindness in the elderly, is a bilateral ocular condition that affects the central area of retina known as the macula. The macula lutea, which derives its name from the deposition of yellow …
Steve Fisher, Geoffrey P. Lewis, Kenneth A Linberg, Edward Barawid and Mark V. Verardo 1. Introduction. What is retinal detachment? The retina is firmly attached to the apical surface of the retinal pigmented epithelium, or RPE (see earlier retinal anatomy sections). When the retina is separated from its normal position apposed to the …
Donnell J. Creel 1. Introduction Electrophysiological testing of patients with retinal disease began in clinical departments in the late nineteen forties. Under the influence of the Swedish pioneers, Holmgren (1865) and Granit (1933), the electroretinogram was being dissected into component parts and early intraretinal electrode studies were beginning to tell which cells or cell …
Ido Perlman 1. Historical view. As early as 1865 Holmgren found that a light stimulus could cause a change in the electrical potential of the amphibian eye. Shortly afterwards, similar findings were reported by Dewar from Scotland. He showed that light illumination through the pupil, which had previously been covered, caused a …
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Frederic Gaillard and Yves Sauve 1. Introduction Injury to the brain areas concerned with vision can cause a variety of disorders ranging from visual field defects to much more complex deficits like visual agnosia. It all depends on the location and the extent of the damage. Injury to the occipital striate cortex results in corresponding …
Yves Sauve and Frederic Gallard 1. Introduction “…once development was ended, the founts of growth and regeneration of the axons and dendrites dried up irrevocably. In adult centres the nerve paths are something fixed, ended, immutable. Everything may die, nothing may be regenerated. It is for the science of the future to change, if possible, …
Sam Nona 1. Overview. The visual system of the goldfish has been the subject of intensive studies for over a quarter of a century. It differs from the visual system of most other vertebrates, including mammals, in that it continues to grow by the addition of new neurons throughout much of the animal’s …
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Matthew Schmolesky The human visual system can detect and discriminate between an incredibly diverse assortment of stimuli that may be chromatic or achromatic, in motion or not, pattered or unpatterned, two-dimensional or three. Remarkably, the neural end-product of visual stimuli impacting upon the retina is, in one sense, always the same. After the complexities …
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Michael Kalloniatis and Charles Luu 1. Introduction. Visual acuity is the spatial resolving capacity of the visual system. This may be thought of as the ability of the eye to see fine detail. There are various ways to measure and specify visual acuity, depending on the type of acuity task used. Visual acuity is …
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Ralph Nelson and Victoria Connaughton 1. Introduction. Retinal ganglion cells are typically only two synapses distant from retinal photoreceptors, yet ganglion cell responses are far more diverse than those of photoreceptors. The most direct pathway from photoreceptors to ganglion cells is through retinal bipolar cells. Thus, it is of great interest to understand how bipolar …
Victoria Connaughton 1. General overview of synaptic transmission. Cells communicate with each other electrically, through gap junctions, and chemically, using neurotransmitters. Chemical synaptic transmission allows nerve signals to be exchanged between cells which are electrically isolated from each other. The chemical messenger, or neurotransmitter, provides a way to send the signal across the extracellular space, …