Related topics: nerve cells , blindness
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.
For more information about Retina, read the full article at
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News tagged with retina
Stem-cell activators switch function, repress mature cells
Dec 16, 2009 |
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In a developing animal, stem cells proliferate and differentiate to form the organs needed for life. A new study shows how a crucial step in this process happens and how a reversal of that step contributes to cancer.
Myopia appears to have become more common
Dec 14, 2009 |
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Myopia (nearsightedness) may have been more common in Americans from 1999 to 2004 than it was 30 years ago, according to a report in the December issue of Archives of Ophthalmology.
Coaxing injured nerve fibers to regenerate by disabling 'brakes' in the system
Medicine & Health / Neuroscience
Dec 09, 2009 |
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Brain and spinal-cord injuries typically leave people with permanent impairment because the injured nerve fibers (axons) cannot regrow. A study from Children's Hospital Boston, published in the December 10 ...
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 ...
Scientists rescue visual function in rats using induced pluripotent stem cells
Dec 03, 2009 |
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An international team of scientists has rescued visual function in laboratory rats with eye disease by using cells similar to stem cells. The research shows the potential for stem cell-based therapies to treat ...
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 ...
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. ...
Eye floaters and flashes of light linked to retinal tear, detachment
Nov 24, 2009 |
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Suddenly seeing floaters or flashes of light may indicate a serious eye problem that - if untreated - could lead to blindness, a new study shows.
Discoveries shed new light on how the brain processes what the eye sees
Medicine & Health / Neuroscience
Jun 02, 2009 |
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Researchers at the Center for Molecular and Behavioral Neuroscience (CMBN) at Rutgers University in Newark have identified the need to develop a new framework for understanding "perceptual stability" and how ...
Scientists Find First Creature With Eyes That Use Both Refractive and Reflective Optics
Jan 27, 2009 |
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Florida Atlantic University researcher and member of the Center for Ocean Exploration and Deep-Sea Research at Harbor Branch Oceanographic Institute, Dr. Tamara Frank, was part of an international research ...
How the retina works: Like a multi-layered jigsaw puzzle of receptive fields
Apr 07, 2009 |
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About 1.25 million neurons in the retina -- each of which views the world only through a small jagged window called a receptive field -- collectively form the seamless picture we rely on to navigate our environment. ...
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 ...
Researchers develop camera for the blind
Jan 12, 2009 |
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(PhysOrg.com) -- Elizabeth Goldring smiles as she shows a visitor photos she's taken — and can see — with her blind eye.
Researchers' vision: restoring sight through artificial retinas
Dec 30, 2008 |
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Scientists are testing artificial retinas that they hope can restore partial sight to people who've lost their vision to the most common causes of blindness.
Bright lights, not-so-big pupils
Dec 31, 2008 |
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A team of Johns Hopkins neuroscientists has worked out how some newly discovered light sensors in the eye detect light and communicate with the brain. The report appears online this week in Nature.
