News tagged with retina

Related topics: cells , brain , eye , neurons , stem cells

New function for rods in daylight

(Medical Xpress)—Vision – so crucial to human health and well-being – depends on job-sharing by just a few cell types, the rod cells and cone cells, in our retina. Botond Roska and his group have identified ...

Nov 19, 2014
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Seven US-based researchers share $1.3M eyesight prize

Seven U.S.-based researchers are sharing a €1 million ($1.3 million) prize from a Portuguese foundation for their work developing treatment for angiogenic diseases of the retina, the leading cause of blindness in the developed ...

Sep 10, 2014
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How to build a brain-machine interface

Devices that tap directly into the nervous system can restore sensation, movement or cognitive function. These technologies, called brain-machine interfaces or BMIs, are on the rise, increasingly providing ...

Apr 25, 2014
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Distribution of photoreceptors in the retina of mice

Guppies, hyenas and mice share one particular retinal specialization in their eye: Photoreceptors ("cones") sensitive to 'green' light are largely located in the top half of the eye, whereas cones sensitive to 'blue' light ...

Dec 05, 2013
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Retina

The 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.

This text uses material from Wikipedia licensed under CC BY-SA