Neuroscience

Protein tenascin-C important in retinal blood flow disorders

Many eye diseases are associated with a restricted blood supply, known as ischaemia, which can lead to blindness. The role of the protein tenascin-C, an extracellular matrix component, in retinal ischaemia was investigated ...

Neuroscience

Diverse neural signals are key to rich visual information

Visual sensation begins at the retina, which is the neural tissue located at the back of eyeballs. It has been known that the retina detects light using photoreceptors which are light-sensitive nerve cells.In case of retinal ...

Medical research

A rift in the retina may help repair the optic nerve

In experiments in mouse tissues and human cells, Johns Hopkins Medicine researchers say they have found that removing a membrane that lines the back of the eye may improve the success rate for regrowing nerve cells damaged ...

Medical research

Scientists create functional human retinas in a dish

Scientists have generated accurate replications of human retinas in culture that can be used to pinpoint the specific types of cells affected by genetic eye diseases. The culmination of a six-year effort, this achievement ...

page 1 from 30

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