Cone cell

A light-sensitive photoreceptor in the retina that supports color vision and high-acuity vision in bright conditions. Its three human types differ in the wavelengths of light to which they are most sensitive.

Phototransduction: The conversion of light into electrical signals by photoreceptor cells. Cone cells use this cascade to turn absorbed photons into changes in membrane voltage.
Retina: The light-sensitive neural tissue lining the back of the eye. Cone cells are one of the retina’s two main classes of photoreceptor.
Color vision: The visual capacity to distinguish light by its spectral composition. Comparisons among cone responses provide the basis for human color vision.
Rod cell: A retinal photoreceptor specialized for sensitive vision in dim light, with little role in color discrimination. Rods outperform cones in darkness, while cones provide color and fine detail in brighter conditions.
Photopsin: A light-sensitive pigment found in cone cells, formed from an opsin protein and a retinal molecule. Different photopsins give cone types their distinct spectral sensitivities.
Fovea centralis: A small central retinal region with the highest density of cone cells and the sharpest visual acuity. Its cone-rich center supports detailed central vision.
Photopic vision: Vision under bright-light conditions, mediated chiefly by cone photoreceptors. Cone cells dominate sight when illumination is high.
Mesopic vision: Vision under intermediate illumination, when both rods and cones contribute to sight. This lighting range falls between cone-dominated daylight and rod-dominated darkness.
Trichromacy: Color vision based on comparing signals from three classes of photoreceptors with different spectral sensitivities. The three human cone classes provide the inputs for ordinary trichromatic color vision.
Retinal ganglion cell: A retina neuron whose axon carries visual signals toward the brain through the optic nerve. Cone-derived signals reach the optic nerve through retinal circuits that include these cells.

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