The Organization of the Retina and Visual System
By Helga Kolb, Ralph Nelson, Peter Ahnelt, Isabel Ortuño-Lizarán and Nicolas Cuenca Abstract We summarize the development, structure, different neural types and neural circuitry in the human fovea. The foveal pit is devoid of rod photoreceptors and of secondary and tertiary neurons, allowing light to directly stimulate cones and give us maximal visual acuity. The …
Stuart Trenholm1 and Gautam B. Awatramani2 1Assistant Professor, Montreal Neurological Institute, McGill University, Montreal, Canada: stuart.trenholm@mcgill.ca 2Associate Professor, Department of Biology, University of Victoria, Victoria, Canada: gautam@uvic.ca Abstract Gap junctions are recognized in the electron microscope as dense starchy areas of opposed membrane between two cells. Small tracer molecules such as Neurobiotin pass through the …
The Science Behind Myopia Brittany J. Carr and William K. Stell INTRODUCTION Myopia (near-sightedness) is the most common refractive vision disorder in children. It is characterized by blurring of objects viewed at a distance, and is commonly the result of abnormal elongation of the eyeball – which causes the refractive image formed by the cornea …
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Bryan William Jones, Robert E. Marc and Rebecca L. Pfeiffer 1. Introduction Retinal degeneration and remodeling encompasses a group of pathologies at the molecular, cellular and tissue levels that are initiated by inherited retinal diseases like retinitis pigmentosa (RP), genetic and environmental diseases like age-related macular degeneration (AMD) and other insults to the eye/retina …
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, …
Ning Tian Introduction The neuronal information of the visual scene that is processed by the retina is conducted to the brain by a set of separate spatio-temporal synaptic pathways. The morphological basis for the formation of these parallel synaptic pathways is the laminar-specific structure of the retina, in which specific subtypes of retinal neurons …
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 …
Michael Kalloniatis and Charles Luu Overview. Colour vision processing in the primate visual system is initiated by absorption of light by three different spectral classes of cones. Consequently, colour vision is described as being trivariant or trichromatic, and initial psychophysical studies demonstrated that colours could be matched by the use of three different primaries. In …
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Josh Morgan and Rachel Wong 1. Introduction. Synaptic connections of the vertebrate retina are organized into distinct laminae (Figure 1). In the outer retina, photoreceptors contact horizontal cells and bipolar cells within a single lamina, the outer plexiform layer (OPL). Within the inner retina, synapses between retinal ganglion cells and their presynaptic partners, the …
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, …
Yingbin Fu 1. Introduction. Vertebrates rely on retinal rods and cones for the conventional, image-forming vision while non-image-forming vision is mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) (see Part II Chapter 7). Rods are specialized for low-light vision. They are extremely sensitive and can signal the absorption of single photons. Cones mediate …
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Helga Kolb 1. General characteristics. The specialized cone pathways of the central fovea of human and monkey retinas have the least convergence and the greatest resolution capabilities of the visual system. This is accomplished by making the connections as “private” as possible and narrowing them to a one to one relationship in the …