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Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina.A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
In physiology, transduction is the translation of arriving stimulus into an action potential by a sensory receptor. It begins when stimulus changes the membrane potential of a sensory receptor . A sensory receptor converts the energy in a stimulus into an electrical signal. [ 1 ]
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Proteins responsible for detecting stimuli are generally termed receptors , although in some cases the term sensor is used. [ 1 ]
Five classical groups of opsins are involved in vision, mediating the conversion of a photon of light into an electrochemical signal, the first step in the visual transduction cascade. Another opsin found in the mammalian retina, melanopsin, is involved in circadian rhythms and pupillary reflex but not in vision. Humans have in total nine opsins.
The path of a visual signal is described by the phototransduction cascade, the mechanism by which the energy of a photon signals a mechanism in the cell that leads to its electrical polarization. This polarization ultimately leads to either the transmittance or inhibition of a neural signal that will be fed to the brain via the optic nerve. The ...
The amacrine cells also introduce lateral inhibition to the axon terminal, serving various visual functions including efficient signal transduction with high signal-to-noise ratio. [ 3 ] The mechanism for producing the center of a bipolar cell's receptive field is well known: direct innervation of the photoreceptor cell above it, either through ...
An opsin absorbs a photon (a particle of light) and transmits a signal to the cell through a signal transduction pathway, resulting in hyper-polarization of the photoreceptor. Rods and cones differ in function. Rods are found primarily in the periphery of the retina and are used to see at low levels of light. Each human eye contains 120 million ...
Transduction is the process through which energy from environmental stimuli is converted to neural activity. The retina contains three different cell layers: photoreceptor layer, bipolar cell layer, and ganglion cell layer. The photoreceptor layer where transduction occurs is farthest from the lens.