Retina
hideThe vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centers of the brain through the fibers of the optic nerve.
In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, so the retina is considered part of the central nervous system (CNS).. It is the only part of the CNS that can be imaged non-invasively in the living organism.
The retina is a complex, layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are mainly of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of colour. A third, much rarer type of photoreceptor, the photosensitive ganglion cell, is important for reflexive responses to bright daylight.
Neural signals from the rods and cones undergo complex processing by other neurons of the retina. The output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve. Several important features of visual perception can be traced to the retinal encoding and processing of light.
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News tagged with retina
Engineers Will Create Planetary Rover From Retinal Implant Test Robot
Nov 11, 2009 |
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(PhysOrg.com) -- The research, led by Wolfgang Fink, will aid both people with visual impairments and scientists involved in planetary exploration.
Study finds lack of VEGF can cause defects similar to dry macular degeneration
Nov 02, 2009 |
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Scientists at Schepens Eye Research Institute have found that when the eye is missing a diffusible form of vascular endothelial growth factor (VEGF), i.e. one that when secreted can reach other cells at a distance, the retina ...
Sight gone, but not necessarily lost? Researchers find life in blood-starved retinas
Oct 30, 2009 |
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Like all tissues in the body, the eye needs a healthy blood supply to function properly. Poorly developed blood vessels can lead to visual impairment or even blindness. While many of the molecules involved in guiding the ...
Two Retinal Imaging Display Devices at Prototype Stage
Electronics / Consumer & Gadgets
Oct 30, 2009 |
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(PhysOrg.com) -- NEC and Brother are both developing wearable prototype devices that use Retinal Imaging Display (RID) technology to project images directly on the wearer's retina. NEC's gadget is designed ...
Alzheimer's lesions found in the retina
Oct 21, 2009 |
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(PhysOrg.com) -- The eyes may be the windows to the soul, but new research indicates they also may mirror a brain ravaged by Alzheimer's disease.
Caltech scientists create robot surrogate for blind persons in testing visual prostheses
Technology / Computer Sciences
Oct 19, 2009 |
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Scientists at the California Institute of Technology (Caltech) have created a remote-controlled robot that is able to simulate the "visual" experience of a blind person who has been implanted with a visual ...
A master mechanism for regeneration?
Medicine & Health / Neuroscience
Oct 19, 2009 |
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ANN ARBOR, Mich.---Biologists long have marveled at the ability of some animals to re-grow lost body parts. Newts, for example, can lose a leg and grow a new one identical to the original. Zebrafish can re-grow fins.
Researchers discover mechanism that helps humans see in bright and low light
Medicine & Health / Neuroscience
Oct 13, 2009 |
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Ever wonder how your eyes adjust during a blackout? When we go from light to near total darkness, cells in the retina must quickly adjust. Vision scientists at Washington University School of Medicine in St. ...
Nerve cells live double lives
Medicine & Health / Neuroscience
Oct 06, 2009 |
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(PhysOrg.com) -- Scientists at the Friedrich Miescher Institute for Biomedical Research (part of the Novartis Research Foundation) have identified a new neural circuit in the retina responsible for the detection ...
Babies see it coming
Medicine & Health / Psychology & Psychiatry
Sep 24, 2009 |
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Do infants only start to crawl once they are physically able to see danger coming? Or is it that because they are more mobile, they develop the ability to sense looming danger? According to Ruud van der Weel and Audrey van ...
Visual detection: new neural circuits identified in the retina
Medicine & Health / Neuroscience
Sep 14, 2009 |
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The detection of approaching objects, such as looming predators, is necessary for survival. Which neurons and nerve circuits mediate this function? A new type of nerve cell, sensitive to approaching motion, has recently been ...
New study suggests the brain predicts what eyes in motion will see
Medicine & Health / Neuroscience
Aug 25, 2009 |
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When the eyes move, objects in the line of sight suddenly jump to a different place on the retina, but the mind perceives the scene as stable and continuous. A new study reports that the brain predicts the consequences of ...
Vision researchers see unexpected gain a year into blindness trial
Aug 12, 2009 |
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Scientists have discovered that even in adults born with extremely impaired sight, the brain can rewire itself to recognize sections of the retina that have been restored by gene therapy.
An 'eye catching' vision discovery
Medicine & Health / Neuroscience
Jul 26, 2009 |
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Nearly all species have some ability to detect light. At least three types of cells in the retina allow us to see images or distinguish between night and day. Now, researchers at the Johns Hopkins School of ...
Technology to Treat Blindness Earns Award
Jul 23, 2009 |
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Research performed at Caltech as part of a collaborative U.S. Department of Energy-funded artificial-retina project designed to restore sight to the blind has received one of R&D Magazine's 2009 R&D 100 Awards. ...
