News tagged with retina

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

Bionic eyes offering better sight to blind

A brighter ray of hope is on the horizon for the blind, as scientists improve electronic hardware that creates sight - making it possible, they predict, to read printed text, recognize faces and lead normal, independent lives.

Feb 15, 2015
popularity 234 comments 0

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
popularity 1 comments 0

Temporal processing in the olfactory system

The neural machinery underlying our olfactory sense continues to be an enigma for neuroscience. A recent review in Neuron seeks to expand traditional ideas about how neurons in the olfactory bulb might encode information about ...

May 17, 2013
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New nanotechnology drug to control blindness

The Mexican company "Medical and Surgical Center for Retina" has created a way to deliver drugs in order to avoid risks and painful treatments in people with secondary blindness due to chronic degenerative ...

Jun 25, 2015
popularity 108 comments 0

Mystery of the reverse-wired eyeball solved

From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

Feb 27, 2015
popularity 86 comments 4

Why human eyes are wired backwards

The human eye is optimised to have good colour vision at day and high sensitivity at night. But until recently it seemed as if the cells in the retina were wired the wrong way round, with light travelling ...

Mar 16, 2015
popularity 129 comments 1

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