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- Glossary
Cornea
The cornea is the transparent front part of the outer layer of the eye. It is involved in refracting light, ensuring that the image of a distant object falls on the point of sharpest vision on the retina.
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- Glossary
Convergence
Convergence of neurons occurs when several neurons are connected synaptically to a single transmitting neuron. In the eye, for example, information received by up to 130 receptors is transmitted to only one neuron in the retina. The opposite is divergence, when one neuron transmits signals to several other neurons.
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- Glossary
Lateral inhibition
Lateral inhibition is a principle of neural stimulus processing, according to which the retina, among other things, is structured. There, the nerve cells of an area are interconnected in such a way that when they are excited, they inhibit the activity of the surrounding neurons.
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- Glossary
Opsin
Opsins are light-sensitive proteins in the retina that, together with the chromophore retinal, absorb light and convert it into electrical signals. The following opsins occur in humans: rhodopsin in rods, for twilight vision, S-opsin → short-wave cones (blue), M-opsin → medium-wave cones (green), L-opsin → long-wave cones (red). These three cone opsins enable color vision.
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- Glossary
Papilla
The optic nerve leaves the eye at the papilla, the optic disc. Since there are no photoreceptors at this point on the retina, the optic disc creates a blind spot.
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- Glossary
Rhodopsin
A specific opsin found in the rods of the retina.
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- Glossary
Rods
The rods are light-sensitive cells with high light sensitivity. They react even to weak light and are therefore responsible for scotopic vision, black-and-white vision, and vision at dusk. The rods are concentrated in the outer areas of the retina and therefore do not provide high visual acuity.
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- Glossary
Transducin
A G protein found in the photoreceptors of the retina. It is activated when a photon hits a photopigment and causes the cation channels in the photoreceptor to close. It is therefore an important component of the visual signal transduction cascade.
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- Glossary
Vestibulo-ocular reflex
When we turn our head, our eyes automatically move in the opposite direction. This reflex ensures that a stable image is formed on the retina even when the head moves quickly. This is made possible by the connection between the semicircular canals of the vestibular system and the nerve nuclei of the eye muscles in the brain stem.
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- Glossary
Cones
The cones are a type of photoreceptor in the retina. The three different types of cones – S, M, and L – are each stimulated by short, medium, and long wavelengths of visible light, enabling color vision. They are highly concentrated in the fovea and enable sharp vision.
