Retina

The retina is light-sensitive neural tissue lining the back of the eye. Its photoreceptors convert light into electrical signals that retinal circuits process and send toward the brain.

Photoreceptor cell: A sensory neuron that detects light using photopigments and converts it into changes in electrical activity. Rods and cones initiate retinal responses by detecting incoming photons.
Rods and cones: The two classes of retinal photoreceptors, specialized respectively for dim-light sensitivity and color vision in brighter light. Their different sensitivities define major limits on retinal vision.
Visual acuity: The ability to resolve fine spatial detail, commonly measured with standardized visual tests. The foveal arrangement of retinal cones largely determines high-acuity vision.
Camera obscura: A lightproof chamber that projects an external scene through an aperture onto an interior surface. Unlike a camera obscura’s passive projection, the retina actively transforms and processes light.
Phototransduction: The biochemical process by which light changes a photoreceptor’s membrane potential. It explains how photon absorption becomes an electrical signal in the retina.
Bipolar cell: A retinal neuron that relays signals between photoreceptors and ganglion cells. Bipolar cells provide the main vertical pathways through retinal circuitry.
Color vision: The perception of differences in light wavelength enabled by comparing signals from different cone types. Retinal cone classes provide the signals underlying color discrimination.
Compound eye: An eye composed of many repeated optical units, each with its own light-sensitive elements. Its many facets differ from the vertebrate retina’s continuous neural sheet behind a lens.
Retinal ganglion cell: A retinal neuron whose axon carries visual information out of the eye. Ganglion cells collect processed retinal signals and form the optic nerve.
Horizontal cell: A retinal interneuron that connects photoreceptors and bipolar cells across neighboring retinal regions. Horizontal cells contribute to lateral interactions and center-surround organization.

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