Ido Perlman, Helga Kolb and Ralph Nelson 1. Introduction Horizontal cells are the interneurons of distal vertebrate retina. They provide the pathways for both local and long range interactions between photoreceptors. These interactions are called feedback signals. Feedback signals adjust the gain of photoreceptor synaptic output, both as seen in the horizontal cells themselves …
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Helga Kolb Two or three types of cone photoreceptor and a single type of rod photoreceptor are present in the normal mammalian retina. Some non-mammalian retinas have even more cone types (see later). 1. Light microscopy and ultrastructure of rods and cones. In vertical sections of retina prepared for light microscopy with …
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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 …
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What is glaucoma? David Križaj Abstract Glaucoma, a leading cause of blindness in the world, can be challenging to diagnose because symptoms often appear at late stage of the disease, and challenging to treat because of the irreversible loss of retinal neurons. The term encompasses a heterogenous group of diseases that are characterized by altered …
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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 …
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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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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 …
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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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Donnell J. Creel Introduction The terms visually evoked potential (VEP), visually evoked response (VER) and visually evoked cortical potential (VECP) are equivalent. They refer to electrical potentials, initiated by brief visual stimuli, which are recorded from the scalp overlying visual cortex, VEP waveforms are extracted from the electro-encephalogram (EEG) by signal averaging. VEPs are …
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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 …
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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 …
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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 …
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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 …
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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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