query: where are cone cells located in the eye

pos: Cone cell Cone cell Cone cells, or cones, are one of 3 types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye). They are responsible for color vision and function best in relatively bright light, as opposed to rod cells, which work better in dim light. Cone cells are densely packed in the fovea centralis, a 0.3 mm diameter rod-free area with very thin, densely packed cones which quickly reduce in number towards the periphery of the retina. There are about six to seven million cones in a human eye and are most concentrated towards the macula. The

pos: Cone cell Cone cell Cone cells, or cones, are one of 3 types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye). They are responsible for color vision and function best in relatively bright light, as opposed to rod cells, which work better in dim light. Cone cells are densely packed in the fovea centralis, a 0.3 mm diameter rod-free area with very thin, densely packed cones which quickly reduce in number towards the periphery of the retina. There are about six to seven million cones in a human eye and are most concentrated towards the macula. The

pos: Foveola Foveola The foveola is located within a region called the macula, a yellowish, cone photo receptor filled portion of the human retina. The foveola is approximately 0.35 mm in diameter and lies in the center of the fovea and contains only cone cells, and a cone-shaped zone of Müller cells. In this region the cone receptors are found to be longer, slimmer and more densely packed than anywhere else in the retina, thus allowing that region to have the potential to have the highest visual acuity in the eye. The centre of the foveola is sometimes referred to as the

pos: Cone cell white or have white spots. A white glow in the eye is often seen in photographs taken with a flash, instead of the typical "red eye" from the flash, and the pupil may appear white or distorted. Other symptoms can include crossed eyes, double vision, eyes that do not align, eye pain and redness, poor vision or differing iris colors in each eye. If the cancer has spread, bone pain and other symptoms may occur. Cone cell Cone cells, or cones, are one of 3 types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye). They

pos: Outer plexiform layer Outer plexiform layer The outer plexiform layer (external plexiform layer) is a layer of neuronal synapses in the retina of the eye. It consists of a dense network of synapses between dendrites of horizontal cells from the inner nuclear layer, and photoreceptor cell inner segments from the outer nuclear layer. It is much thinner than the inner plexiform layer, where amacrine cells synapse with retinal ganglion cells. The synapses in the outer plexiform layer are between the rod cell endings or cone cell branched foot plates and horizontal cells. Unlike in most systems, rod and cone cells release neurotransmitters when

pos: Scotopic vision Scotopic vision Scotopic vision is the vision of the eye under low-light levels. The term comes from Greek "skotos", meaning "darkness", and "-opia", meaning "a condition of sight". In the human eye, cone cells are nonfunctional in low visible light. Scotopic vision is produced exclusively through rod cells, which are most sensitive to wavelengths of around 498 nm (green–blue) and are insensitive to wavelengths longer than about 640 nm (red). This condition is called the Purkinje effect. Scotopic vision is dominated by retina amacrine cells, specifically AII-amacrine cells. AII-amacrine cells capture rod bipolar cell input and redistribute it to cone

pos: Cone cell commonly cited figure of six million cone cells in the human eye was found by Osterberg in 1935. Oyster's textbook (1999) cites work by Curcio et al. (1990) indicating an average close to 4.5 million cone cells and 90 million rod cells in the human retina. Cones are less sensitive to light than the rod cells in the retina (which support vision at low light levels), but allow the perception of color. They are also able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods. Cones are

pos: Spectral sensitivity Spectral sensitivity Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience, spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye. It is known that the rod cells are more suited to scotopic vision and cone cells to photopic vision, and that they differ in their sensitivity to different wavelengths of light. It has been established that the maximum spectral sensitivity of the human eye under daylight

pos: Rod cell Rod cell Rod cells are photoreceptor cells in the retina of the eye that can function in less intense light than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 90 million rod cells in the human retina. Rod cells are more sensitive than cone cells and are almost entirely responsible for night vision. However, rods have little role in color vision, which is the main reason why colors are much less apparent in dim light, and not

pos: Rod cell the rods' peak sensitivity (blue-green). Rod cell Rod cells are photoreceptor cells in the retina of the eye that can function in less intense light than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 90 million rod cells in the human retina. Rod cells are more sensitive than cone cells and are almost entirely responsible for night vision. However, rods have little role in color vision, which is the main reason why colors are much less apparent

pos: Retinal precursor cells Retinal precursor cells Retinal precursor cells are biological cells that differentiate into the various cell types of the retina during development. In the vertebrate, these retinal cells differentiate into seven cell types, including retinal ganglion cells, amacrine cells, bipolar cells, horizontal cells, rod photoreceptors, cone photoreceptors, and Müller glia cells. During embryogenesis, retinal cells originate from the anterior portion of the neural plate termed the eye field. Eye field cells with a retinal fate express several transcription factor markers including Rx1, Pax6, and Lhx2. The eye field gives rise to the optic vesicle and then to the optic cup. The

pos: Trichromacy Trichromacy Trichromacy or trichromatism is the possessing of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats. The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different absorption spectra. In actuality the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the rod cells may contribute to color

pos: Blue cone monochromacy Blue cone monochromacy Blue cone monochromacy (BCM) is an inherited eye disease that causes severely impaired color discrimination, low vision, nystagmus and photophobia due to the absence of functionality of red (L) and green (M) cone photoreceptor cells in the retina. This form of retinal disorder is a recessive X-linked disease and manifests its symptoms in early infancy. Blue cone monochromacy is considered a stationary (non-progressive) disease, although there is evidence of disease progression with macular degeneration in many patients. Cone photoreceptor cells in the retina are responsible for day-light vision, color vision, visual acuity and sight in the central

pos: RGB color model spaces for more details. The choice of primary colors is related to the physiology of the human eye; good primaries are stimuli that maximize the difference between the responses of the cone cells of the human retina to light of different wavelengths, and that thereby make a large color triangle. The normal three kinds of light-sensitive photoreceptor cells in the human eye (cone cells) respond most to yellow (long wavelength or L), green (medium or M), and violet (short or S) light (peak wavelengths near 570 nm, 540 nm and 440 nm, respectively). The difference in the signals received from

pos: Cone cell short. The three types have peak wavelengths near 564–580 nm, 534–545 nm, and 420–440 nm, respectively, depending on the individual. While it has been discovered that there exists a mixed type of bipolar cells that bind to both rod and cone cells, bipolar cells still predominantly receive their input from cone cells. Cone cells are somewhat shorter than rods, but wider and tapered, and are much less numerous than rods in most parts of the retina, but greatly outnumber rods in the fovea. Structurally, cone cells have a cone-like shape at one end where a pigment filters incoming light, giving

pos: Outer plexiform layer not receiving a light signal. Outer plexiform layer The outer plexiform layer (external plexiform layer) is a layer of neuronal synapses in the retina of the eye. It consists of a dense network of synapses between dendrites of horizontal cells from the inner nuclear layer, and photoreceptor cell inner segments from the outer nuclear layer. It is much thinner than the inner plexiform layer, where amacrine cells synapse with retinal ganglion cells. The synapses in the outer plexiform layer are between the rod cell endings or cone cell branched foot plates and horizontal cells. Unlike in most systems, rod and

pos: Spectral sensitivity spectral sensitivity may be expressed as a spectral responsivity, with units such as amperes per watt. Spectral sensitivity Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal. In visual neuroscience, spectral sensitivity is used to describe the different characteristics of the photopigments in the rod cells and cone cells in the retina of the eye. It is known that the rod cells are more suited to scotopic vision and cone cells to photopic vision, and that they differ in their sensitivity to different wavelengths of

pos: Eye main phyla. In most vertebrates and some molluscs, the eye works by allowing light to enter and project onto a light-sensitive panel of cells, known as the retina, at the rear of the eye. The cone cells (for colour) and the rod cells (for low-light contrasts) in the retina detect and convert light into neural signals for vision. The visual signals are then transmitted to the brain via the optic nerve. Such eyes are typically roughly spherical, filled with a transparent gel-like substance called the vitreous humour, with a focusing lens and often an iris; the relaxing or tightening of

pos: Zebrafish how the cone cells of the retina become arranged into the so-called 'cone mosaic'. Zebrafish, in addition to certain other teleost fish, are particularly noted for having extreme precision of cone cell arrangement. This study of the zebrafish's retinal characteristics has also extrapolated into medical enquiry. In 2007, researchers at University College London grew a type of zebrafish adult stem cell found in the eyes of fish and mammals that develops into neurons in the retina. These could be injected into the eye to treat diseases that damage retinal neurons—nearly every disease of the eye, including macular degeneration, glaucoma, and

pos: Eagle eye who weighs . Although the size of the eagle eye is about the same as of a human being, the back side shape of the eagle eye is flatter. An eagle's retina allows for a higher Nyquist limit. Its retina is more pronounced with rod cells and cone cells. In the eagle, the retina's fovea has one million cells per mm as compared to 200,000 per mm in humans. Eagles have a second fovea and three eyelids (two of which are visible). The second fovea in eagles gives them better and sharper vision while the long, narrow ribbon-shaped area that

pos: Stiles–Crawford effect to the Stiles–Crawford effect. Due to the complexity of a single cone photoreceptor and the layers of the retina which lie ahead of the cone photoreceptor on the light path, as well as the randomness associated with the distribution and orientation of cone photoreceptors, it is extremely difficult to fully model all of the factors which may affect the production of the visual stimulus in an eye. Unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. It has been proposed that these unique Müller cells caused angle dependent light reflection and thereby

pos: Retinal ganglion cell layer, reducing the quality of vision. There are human eye diseases where this does, in fact, happen. In some vertebrates, for example the chicken, the ganglion cell axons "are" myelinated inside the retina. [[Category:Histology]] [[Category:Human eye anatomy]] [[Category:Visual system]] [[Category:Human cells]] [[Category:Neurons]] Retinal ganglion cell A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and retina amacrine cells. Retina amacrine cells, particularly narrow field cells, are important for creating functional subunits

pos: Eye three types of cones, maximally sensitive to long-wavelength, medium-wavelength, and short-wavelength light (often referred to as red, green, and blue, respectively, though the sensitivity peaks are not actually at these colours). The colour seen is the combined effect of stimuli to, and responses from, these three types of cone cells. Cones are mostly concentrated in and near the fovea. Only a few are present at the sides of the retina. Objects are seen most sharply in focus when their images fall on the fovea, as when one looks at an object directly. Cone cells and rods are connected through intermediate

pos: Disc shedding Disc shedding Disc shedding is the process by which photoreceptors in the eye are renewed. The retina contains two types of photoreceptor – rod cells and cone cells. There are about 6-7 million cones that provide color vision to the eye, and they are very concentrated in a central spot in the retina, called the macula. However, the rods are much more numerous – about 120 million – and are also more sensitive than the cones. These rods are responsible for scotopic (night) vision, our most sensitive motion detection, and our peripheral vision. Vertebrate photoreceptors are composed of a photosensitive

pos: Opsin opsins are a subset of C-opsins (ciliary). They are expressed in the vertebrate retina and mediate vision. They can be further subdivided into rod opsins and four types of cone opsin. Rod opsins (rhodopsins, usually denoted Rh), are used in dim-light vision, are thermally stable, and are found in the rod photoreceptor cells. Cone opsins, employed in color vision, are less-stable opsins located in the cone photoreceptor cells. Cone opsins are further subdivided according to their absorption maxima ("λ"), the wavelength at which the highest light absorption is observed. Evolutionary relationships, deduced using the amino acid sequence of the opsins,

pos: Trichromacy not very intense yellowish light would produce a stronger response from M cones than from other cones. Thus trichromatic color vision is accomplished by using combinations of cell responses. It is estimated that the average human can distinguish up to seven million different colors. Trichromacy Trichromacy or trichromatism is the possessing of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats. The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different

pos: Young–Helmholtz theory and Mollon, who obtained microspectrophotopic readings of single eye cone cells. Earlier evidence for the theory had been obtained by looking at light reflected from the retinas of living humans, and absorption of light by retinal cells removed from corpses. Young–Helmholtz theory Hermann von Helmholtz developed the theory further in 1850: that the three types of cone photoreceptors could be classified as short-preferring (blue), middle-preferring (green), and long-preferring (red), according to their response to the wavelengths of light striking the retina. The relative strengths of the signals detected by the three types of cones are interpreted by the brain as

pos: Scotopic vision scotopic and photopic efficacies is only around 2.5 counted at peak sensitivity the ratio increases strongly below 500 nm. Another reason that vision is poor under scotopic vision is that rods, which are the only cells active under scotopic vision, converge to a smaller number of neurons in the retina. This many-to-one ratio leads to poor spatial frequency sensitivity. Scotopic vision Scotopic vision is the vision of the eye under low-light levels. The term comes from Greek "skotos", meaning "darkness", and "-opia", meaning "a condition of sight". In the human eye, cone cells are nonfunctional in low visible light. Scotopic

pos: Muller glia cell can then divide and differentiate into a number of retinal cell types, including photoreceptor cells, that may have been damaged during injury. Additionally, further research has shown that Müller glia act as light collectors in the mammalian eye, analogous to the fiber optic plate, funneling light to the rod and cone photoreceptors. Aquaporin-4 in Müller cell in rat, transfer water to vitreous body. Muller glia Müller glia, or Müller cells, are a type of retinal glial cells, first recognized and described by Heinrich Müller. They are found in the vertebrate retina, which serve as support cells for the neurons,

pos: Human eye Human eye The human eye is an organ which reacts to light and pressure. As a sense organ, the mammalian eye allows vision. Human eyes help to provide a three dimensional, moving image, normally coloured in daylight. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can differentiate between about 10 million colors and is possibly capable of detecting a single photon. Similar to the eyes of other mammals, the human eye's non-image-forming photosensitive ganglion cells in the retina receive light signals which affect adjustment

pos: Retinal summation to low light levels, where the signal is summed before reaching the brain—presumably advantageous when the signals reaching individual photoreceptor cells are weak. High retinal summation is an adaptation to low light levels, and low retinal summation to high light levels (thus sharpening the images). Retinal summation Retinal summation describes the relationship between different types of cells in the retina: cone photoreceptor cells, bipolar cells, and ganglion cells. With high retinal summation, a large number of photoreceptor cells converge on a smaller number of bipolar cells in transferring their signals to ganglion cells. Zero summation occurs when each cone photoreceptor

pos: Tuatara of photoreceptive cells, all with fine structural characteristics of retinal cone cells used for both day and night vision, and a tapetum lucidum which reflects onto the retina to enhance vision in the dark. There is also a third eyelid on each eye, the nictitating membrane. The tuatara has a third eye on the top of its head called the parietal eye. It has its own lens, a parietal plug which resembles a cornea, retina with rod-like structures, and degenerated nerve connection to the brain. The parietal eye is only visible in hatchlings, which have a translucent patch at the

pos: Flicker fusion threshold on the retina where the perceived image falls: the rod cells of the human eye have a faster response time than the cone cells, so flicker can be sensed in peripheral vision at higher frequencies than in foveal vision. This is essentially the concept known as the Ferry-Porter law, where it may take some increase in brightness, by powers of ten, to require as many as 60 flashes to achieve fusion, while for rods, it may take as little as four flashes, since in the former case each flash is easily cut off, and in the latter it lasts long

pos: Blue cone monochromacy restore colour vision through an AAV gene therapy that introduced a new opsin in the primate retina. A mouse model of blue cone monochromacy has been treated with gene-based therapy. Blue cone monochromacy Blue cone monochromacy (BCM) is an inherited eye disease that causes severely impaired color discrimination, low vision, nystagmus and photophobia due to the absence of functionality of red (L) and green (M) cone photoreceptor cells in the retina. This form of retinal disorder is a recessive X-linked disease and manifests its symptoms in early infancy. Blue cone monochromacy is considered a stationary (non-progressive) disease, although there is

pos: Dopamine and periventricular nuclei, projects to several areas of the hypothalamus, and participates in the control of gonadotropin-releasing hormone, which is necessary to activate the development of the male and female reproductive systems, following puberty. An additional group of dopamine-secreting neurons is found in the retina of the eye. These neurons are amacrine cells, meaning that they have no axons. They release dopamine into the extracellular medium, and are specifically active during daylight hours, becoming silent at night. This retinal dopamine acts to enhance the activity of cone cells in the retina while suppressing rod cells—the result is to increase sensitivity

pos: Visual processing The retina is where a group of light-sensing cells, called photoreceptors are located. There are two types of photoreceptors: rods and cones. Rods are sensitive to dim light and cones are better able to transduce bright light. Photoreceptors connect to bipolar cells, which induce action potentials in retinal ganglion cells. These retinal ganglion cells form a bundle at the optic disc, which is a part of the optic nerve. The two optic nerves from each eye meet at the optic chiasm, where nerve fibers from each nasal retina cross which results in the right half of each eye's visual field

pos: Tetrachromacy the brain would respond if presented with a new color channel. Mice, which normally have only two cone pigments, can be engineered to express a third cone pigment, and appear to demonstrate increased chromatic discrimination, arguing against some of these obstacles; however, the original publication's claims about plasticity in the optic nerve have also been disputed. Humans cannot see ultraviolet light directly because the lens of the eye blocks most light in the wavelength range of 300–400 nm; shorter wavelengths are blocked by the cornea. The photoreceptor cells of the retina are sensitive to near ultraviolet light, and people lacking

pos: Optics which are sensitive to different aspects of light. Rod cells are sensitive to the intensity of light over a wide frequency range, thus are responsible for black-and-white vision. Rod cells are not present on the fovea, the area of the retina responsible for central vision, and are not as responsive as cone cells to spatial and temporal changes in light. There are, however, twenty times more rod cells than cone cells in the retina because the rod cells are present across a wider area. Because of their wider distribution, rods are responsible for peripheral vision. In contrast, cone cells are

pos: Retina horizontal cell However, when recordings are made from parts of the cone that are distant from the cone terminals that synapse onto bipolar cells, center-surround antagonism seems to be less reliable in cones than in bipolar cells. As the invaginating synapses from horizontal cells are made onto cone terminals, the center-surround antagonism of cones is thought to be more reliably present in cone terminals. Retina horizontal cell Horizontal cells are the laterally interconnecting neurons having cell bodies in the inner nuclear layer of the retina of vertebrate eyes. They help integrate and regulate the input from multiple photoreceptor cells. Among their functions,

pos: Macula of retina is seen when viewed from the pupil, as in ophthalmoscopy or retinal photography. The anatomical macula is defined histologically in terms of having two or more layers of ganglion cells. The umbo is the center of the foveola which in turn is located at the center of the fovea. The fovea is located near the center of the macula. It is a small pit that contains the largest concentration of cone cells. The retina contains two types of photosensitive cells, the rod cells and the cone cells. Because the macula is yellow in colour it absorbs excess blue and ultraviolet

pos: Oilbird eyes are small, but the pupils are relatively large, allowing the highest light-gathering capacity of any bird (f-number of 1.07). The retina is dominated by rod cells, 1,000,000 rods per mm, the highest density of any vertebrate eye, which are organised in layers, an arrangement unique among birds but shared by deep-sea fish. They have low numbers of cone cells, and the whole arrangement would allow them to capture more light in low light conditions but probably have poor vision in daylight. Although they have specially adapted vision to forage by sight, they are among the few birds known to

pos: Optics and vision conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. The human eye's non-image-forming photosensitive ganglion cells in the retina receive the light signals which affect adjustment of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock. Visual acuity is acuteness or clearness of vision, especially form vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity

pos: Colour centre This is more important for perceiving the colour of objects and pictures. The double-opponent cells are receptive to opposite inputs from different cone cells in the retina. This is ideal for identifying contrasting colours, such as red and green. [1] Double-opponent cells are particularly important in computing local cone ratios from visual information from their receptive fields. Single opponent colour-sensitive neurons can be divided into two categories depending on the signals they receive from the cone cells: L-M neurons and S/(L+M) neurons. The three types of cone cells, small (S), medium (M), and long (L), detect different wavelengths across the

pos: Barreleye the genera "Opisthoproctus" and "Macropinna", the extremely slender and elongated spookfishes of the genera "Dolichopteryx" and "Bathylychnops", and the intermediate fusiform spookfishes of the genera "Rhynchohyalus" and "Winteria". All species have large, telescoping eyes, which dominate and protrude from the head, but are enclosed within a large transparent dome of soft tissue. These eyes generally gaze upwards, but can also be directed forwards. The opisthoproctid eye has a large lens and a retina with an exceptionally high complement of rod cells and a high density of rhodopsin (the "visual purple" pigment); no cone cells are present. To better serve their

pos: Scanning laser ophthalmoscopy differentiate tissues within the eye and create a cross section of a living patients’ retina non-invasively. It actually has greater axial resolution than AOSLO. However, AOSLO represents a method with much greater translational resolution than OCT and can thus be used to track minor lateral physical changes such as the effects of eye movements on the retina. A combination of AOSLO and OCT has recently been attempted in one apparatus to produce the first three-dimensional images of individual cone cells and illustrate the overall cone mosaic near the fovea at high speeds. Scanning laser ophthalmoscopy Scanning laser ophthalmoscopy (SLO) is

pos: Color space types of photoreceptors (now known as cone cells) in the eye, each of which was sensitive to a particular range of visible light. Hermann von Helmholtz developed the Young–Helmholtz theory further in 1850: that the three types of cone photoreceptors could be classified as short-preferring (blue), middle-preferring (green), and long-preferring (red), according to their response to the wavelengths of light striking the retina. The relative strengths of the signals detected by the three types of cones are interpreted by the brain as a visible color. But it's not clear that they thought of colours as being points in color space.

pos: RGS9 RGS9 Regulator of G-protein signalling 9, also known as RGS9, is a human gene, which codes for a protein involved in regulation of signal transduction inside cells. Members of the RGS family, such as RGS9, are signaling proteins that suppress the activity of G proteins by promoting their deactivation.[supplied by OMIM] There are two splice isoforms of RGS9 with quite different properties and patterns of expression. RGS9-1 is mainly found in the eye and is involved in regulation of phototransduction in rod and cone cells of the retina, while RGS9-2 is found in the brain, and regulates dopamine and opioid

pos: Color television still the standard elsewhere. The human eye's detection system, which is in the retina, consists primarily of two types of light detectors: rod cells that capture light, dark, and shapes/figures, and the cone cells that detect color. A typical retina contains 120 million rods and 4.5 million to 6 million cones, which are divided among three groups that are sensitive to red, green, and blue light. This means that the eye has far more resolution in brightness, or "luminance", than in color. However, post-processing of the optic nerve and other portions of the human visual system combine the information from

pos: Gene therapy for color blindness of 2018 there is no medical entity offering this treatment, and no clinical trials available for volunteers. The retina of the human eye contains photoreceptive cells called cones that allow color vision. A normal trichromat individual possesses three different types of cones to distinguish different colors within the visible spectrum from 380 nm to 740 nm. The three types of cones are designated L, M, and S cones, and each type is sensitive to a certain range of wavelength of light depending on what photopigment it contains. More specifically, the L cone absorbs around 560 nm, the M cone absorbs

pos: Pupil and thus attain their expected acuity; in the dark this is not necessary, so it is chiefly concerned with admitting sufficient light into the eye. When bright light is shone on the eye, light sensitive cells in the retina, including rod and cone photoreceptors and melanopsin ganglion cells, will send signals to the oculomotor nerve, specifically the parasympathetic part coming from the Edinger-Westphal nucleus, which terminates on the circular iris sphincter muscle. When this muscle contracts, it reduces the size of the pupil. This is the pupillary light reflex, which is an important test of brainstem function. Furthermore, the pupil

pos: Photoreceptor cell amacrine cells in the retina. The final result is differing populations of ganglion cells in the retina, a sub-population of which is also intrinsically photosensitive, using the photopigment melanopsin. A non-rod non-cone photoreceptor in the eyes of mice, which was shown to mediate circadian rhythms, was discovered in 1991 by Foster "et al." These neuronal cells, called intrinsically photosensitive retinal ganglion cells (ipRGC), are a small subset (≈1–3%) of the retinal ganglion cells located in the inner retina, that is, in front of the rods and cones located in the outer retina. These light sensitive neurons contain a photopigment, melanopsin,

pos: AII amacrine cells small proportion of rods contact the cone bipolar cells directly." AII amacrine cells AII amacrine cells are a subtype of amacrine cells present in the retina of mammals. AII amacrine cell serve the critical role of transferring light signals from rod photoreceptors to the retinal ganglion cells (which contain the axons of the optic nerve) The Classical Rod Pathway described the role of AII amacrine cells in the mammalian retina. This can be summarised as follows: (Once activated, the AII amacrine cell then modulates the cone ON and OFF channels): The ON- and OFF- cone bipolar cells in turn contact

pos: Adaptation (eye) opsin photopigment. The various cone cells are maximally sensitive to either short wavelengths (blue light), medium wavelengths (green light), or long wavelengths (red light). Rod photoreceptors only contain one type of photopigment, rhodopsin, which has a peak sensitivity at a wavelength of approximately 530 nanometers which corresponds to blue-green light. A minor mechanism of adaptation is the pupillary light reflex, adjusting the amount of light that reaches the retina. In response to varying ambient light levels, rods and cones of eye function both in isolation and in tandem to adjust the visual system. Changes in the sensitivity of rods and

pos: Eye tests can this be deduced. Most organisms with colour vision are able to detect ultraviolet light. This high energy light can be damaging to receptor cells. With a few exceptions (snakes, placental mammals), most organisms avoid these effects by having absorbent oil droplets around their cone cells. The alternative, developed by organisms that had lost these oil droplets in the course of evolution, is to make the lens impervious to UV light – this precludes the possibility of any UV light being detected, as it does not even reach the retina. The retina contains two major types of light-sensitive photoreceptor

pos: Bird vision the lens which controls the amount of light entering the eye. At the centre of the iris is the pupil, the variable circular area through which the light passes into the eye. The retina is a relatively smooth curved multi-layered structure containing the photosensitive rod and cone cells with the associated neurons and blood vessels. The density of the photoreceptors is critical in determining the maximum attainable visual acuity. Humans have about 200,000 receptors per mm, but the house sparrow has 400,000 and the common buzzard 1,000,000. The photoreceptors are not all individually connected to the optic nerve, and the

pos: Photopsin absorb light at different wavelengths as retinal-bound pigments. Humans have three different photoreceptor proteins ("photopsin" or "cone opsins") which are found in cone cells and which are responsible for colour vision: George Wald received the 1967 Nobel Prize in Physiology or Medicine for his experiments in the 1950s that showed the difference in absorbance by these photopsins (see image). Photopsin Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the "visual

neg: Mammalian eye cannot see dim stars, or other celestial objects, using central vision because the light from these is not enough to stimulate cone cells. Because cone cells are all that exist directly in the fovea, astronomers have to look at stars through the "corner of their eyes" (averted vision) where rods also exist, and where the light "is" sufficient to stimulate cells, allowing an individual to observe faint objects. Rods and cones are both photosensitive, but respond in different ways to different frequencies of light. They contain different pigmented photoreceptor proteins. Rod cells contain the protein rhodopsin and cone cells contain

neg: Mammalian eye ganglion cells involved in adjusting circadian rhythms and pupil size but probably not involved in vision. Though structurally and metabolically similar, the functions of rods and cones are quite different. Rod cells are highly sensitive to light, allowing them to respond in dim light and dark conditions; however, they cannot detect color differences. These are the cells that allow humans and other animals to see by moonlight, or with very little available light (as in a dark room). Cone cells, conversely, need high light intensities to respond and have high visual acuity. Different cone cells respond to different wavelengths of

neg: Adaptation (eye) the rods taking over after five or more minutes. Cone cells are able to regain maximum retinal sensitivity in 9–10 minutes of darkness whereas rods require 30–45 minutes to do so. Dark adaptation is far quicker and deeper in young people than the elderly. The human eye contains two types of photoreceptors, rods and cones, which can be easily distinguished by their structure. Cone photoreceptors are conical in shape and contain cone opsins as their visual pigments. There exist three types of cone photoreceptors, each being maximally sensitive to a specific wavelength of light depending on the structure of their

neg: Cone cell report the ability to see into the ultraviolet range. At moderate to bright light levels where the cones function, the eye is more sensitive to yellowish-green light than other colors because this stimulates the two most common (M and L) of the three kinds of cones almost equally. At lower light levels, where only the rod cells function, the sensitivity is greatest at a blueish-green wavelength. Cones also tend to possess a significantly elevated visual acuity because each cone cell has a lone connection to the optic nerve, therefore, the cones have an easier time telling that two stimuli are

neg: Impossible color eye in normal circumstances seeing any possible light spectrum. Thus, no object can have an imaginary color. But such imaginary colors are useful as mathematical abstractions for defining color spaces. The spectral sensitivity curve of medium-wavelength ("M") cone cells overlaps those of short-wavelength ("S") and long-wavelength ("L") cone cells. Light of any wavelength that interacts with M cones also interacts with S or L cones, or both, to some extent. Therefore, no wavelength (except perhaps a bit of the far red), and no non-negative spectral power distribution, excites only one sort of cone. If, for example, M cones could be

neg: Adaptation (eye) Adaptation (eye) In ocular physiology, adaptation is the ability of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher illumination levels. Night vision is of a much poorer quality than day vision because it is limited by a reduced resolution and therefore provides the ability to only discriminate between shades of black and white. In order for humans to transition from day to night vision they

neg: Gordon Lynn Walls cells and cone cells in the animal world. He detected the communalities of photoreceptor cells in the vertebrate eye and was first in describing the cone cell as a specialized cell, obviously evolved from an early rod cell. He described the nocturnal bottleneck hypothesis which states that placental mammals were mainly or even exclusively nocturnal through most of their evolutionary story, starting with their origin 225 million years ago, and only ending with the demise of the dinosaurs 66 million years ago. 1958 Walls wrote a chapter in "The eye in evolution", the first volume (780 pages) of Stewart Duke-Elder's

neg: Green the dark-adapted human eye is greatest at about 507nm, a blue-green color, while the light-adapted eye is most sensitive about 555nm, a yellow-green; these are the peak locations of the rod and cone (scotopic and photopic, respectively) luminosity functions. The perception of greenness (in opposition to redness forming one of the opponent mechanisms in human color vision) is evoked by light which triggers the medium-wavelength "M" cone cells in the eye more than the long-wavelength "L" cones. Light which triggers this greenness response more than the yellowness or blueness of the other color opponent mechanism is called green. A green

neg: CIE 1931 color space and John Guild. The experimental results were combined into the specification of the CIE RGB color space, from which the CIE XYZ color space was derived. The CIE 1931 color spaces are still widely used, as is the 1976 CIELUV color space. The human eye with normal vision has three kinds of cone cells that sense light, having peaks of spectral sensitivity in short ("S", – ), middle ("M", – ), and long ("L", – ) wavelengths. These cone cells underlie human color perception in conditions of medium and high brightness; in very dim light color vision diminishes, and the

neg: Mammalian eye the high visual acuity, or the high ability to distinguish detail, of cone cells compared to rods. If a ray of light were to reach just one rod cell, the cell's response may not be enough to hyperpolarize the connected bipolar cell. But because several "converge" onto a bipolar cell, enough transmitter molecules reach the synapses of the bipolar cell to hyperpolarize it. Furthermore, color is distinguishable due to the different iodopsins of cone cells; there are three different kinds, in normal human vision, which is why we need three different primary colors to make a color space. A small

neg: Oil droplet Oil droplet Oil droplets are found in the eyes of some animals, being located in the photoreceptor cells. They are especially common in the eyes of diurnal (active during the day) reptiles (e.g. lizards, turtles) and birds (see bird vision), though are present in other taxa such as lungfish. They are found in cone cells far more often than in rods, suggesting a role in colour vision. Occurrence in rod cells may imply that they have been modified from a cone cell ancestor. They occasionally occur in double cones/double rods. Some oil droplets are coloured, while others appear colourless. They

neg: Parietal eye or pineal gland if mostly endocrine) and the parietal organ (often called the parietal eye, or third eye if it is photoreceptive). It arises as an anterior evagination of the pineal organ or as a separate outgrowth of the roof of the diencephalon. In some species, it protrudes through the skull. The parietal eye uses a different biochemical method of detecting light from that of rod cells or cone cells in a normal vertebrate eye. Many of the oldest fossil vertebrates, including ostracoderms, placoderms, crossopterygians, and even early tetrapods, had a socket in the skull that appears to have held

neg: Oil droplet the hypothesis that this is of net benefit. Oil droplet Oil droplets are found in the eyes of some animals, being located in the photoreceptor cells. They are especially common in the eyes of diurnal (active during the day) reptiles (e.g. lizards, turtles) and birds (see bird vision), though are present in other taxa such as lungfish. They are found in cone cells far more often than in rods, suggesting a role in colour vision. Occurrence in rod cells may imply that they have been modified from a cone cell ancestor. They occasionally occur in double cones/double rods. Some oil

neg: Eye can tweak the peak response by a few nm; pigments in the lens can also filter incoming light, changing the peak response. Many organisms are unable to discriminate between colours, seeing instead in shades of grey; colour vision necessitates a range of pigment cells which are primarily sensitive to smaller ranges of the spectrum. In primates, geckos, and other organisms, these take the form of cone cells, from which the more sensitive rod cells evolved. Even if organisms are physically capable of discriminating different colours, this does not necessarily mean that they can perceive the different colours; only with behavioural

neg: Adaptation (eye) must undergo a dark adaptation period in which each eye adjusts from a high luminescence setting to a low luminescence setting. This adaptation period is different for both rod and cone cells and results from the regeneration of photopigments to restore retinal sensitivity. The human eye can function from very dark to very bright levels of light; its sensing capabilities reach across nine orders of magnitude. This means that the brightest and the darkest light signal that the eye can sense are a factor of roughly 1,000,000,000 apart. However, in any given moment of time, the eye can only sense

neg: Vision span Vision span Vision span or perceptual span is a controversial concept referring to the angular span (vertically and horizontally), within which the human eye has sharp enough vision to perform an action accurately (reading or face recognition). The visual field of the human eye spans approximately 120 degrees of arc. However, most of that arc is peripheral vision. The human eye has much greater resolution in the macula, where there is a higher density of cone cells. The field of view that is observed with sufficient resolution to read text typically spans about 6 degrees of arc, which is wide

neg: Hydrodynamic trapping cells, which are more deformable than healthy cells from the same part of the body. Another method is vorticity induced trapping. This is especially useful for high throughput situations and situations where there is a large difference between the target cells or particles and the other particles in a solution. The vortices can be created by modifying the geometry of channels. Hydrodynamic trapping can also be used to trap and study molecules in lipid bilayers. This is done using hydrodynamic drag forces that are created by a fluid flow through a very small cone shaped pipet located about one micrometer

neg: Transsaccadic memory been found to be involved in initiating and executing saccadic eye movements, which includes the desired speed and direction of the saccade. The cells in these layers are organized in a way that forms a map of the visual field. They are organized according to what direction each cell moves the eye. It has been found that activation of specific cells is directed by where objects in the environment are located in the visual field. Once a new object is detected, the cells that fire the strongest to stimuli within this specific area of the visual field will fire, causing

neg: Tetrachromacy a lens (a condition known as aphakia) see near ultraviolet light (down to 300 nm) as whitish blue, or for some wavelengths, whitish violet, probably because all three types of cones are roughly equally sensitive to ultraviolet light; however, blue cone cells are slightly more sensitive. Tetrachromacy may also enhance vision in dim lighting, or when looking at a screen. Tetrachromacy Tetrachromacy is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye. Organisms with tetrachromacy are called tetrachromats. In tetrachromatic organisms, the sensory color space is four-dimensional, meaning

neg: Intraocular schwannoma including Schwann cells and mast cells among others. In contrast, Neurofibromatosis type II is characterized by schwannomas located on the eighth cranial nerve. This unfortunate placement leads to disruptions in balance, hearing and sometimes even vision. While schwannomas in a general sense can be found in a variety of places where Schwann cells are located, intraocular schwannomas are a rare but serious condition that specifically targets the eye. These tumors are thought to come from Schwann cells of the ciliary nerves and have also been called "pseudomelanomas" and for good reason. They are given this name due to the fact

neg: Bistratified cell made them hard to find. About 8 to 10% of retinal ganglion cells are bistratified cells. They receive inputs from intermediate numbers of rods and cones. They have moderate spatial resolution, moderate conduction velocity, and can respond to moderate-contrast stimuli. They may be involved in color vision. They have very large receptive fields that only have centers (no surrounds) and are always ON to the blue cone and OFF to both the red and green cone. Bistratified cell Bistratified ganglion cell can refer to either of two kinds of retinal ganglion cells whose cell body is located in the ganglion

neg: Fish anatomy Their retinas generally have both rod cells and cone cells (for scotopic and photopic vision), and most species have colour vision. Some fish can see ultraviolet and some can see polarized light. Amongst jawless fish, the lamprey has well-developed eyes, while the hagfish has only primitive eyespots. The ancestors of modern hagfish, thought to be the protovertebrate were evidently pushed to very deep, dark waters, where they were less vulnerable to sighted predators, and where it is advantageous to have a convex eye-spot, which gathers more light than a flat or concave one. Unlike humans, fish normally adjust focus by

neg: Rod cell at all at night. Rods are a little longer and leaner than cones but have the same basic structure. Opsin-containing disks lie at the end of the cell adjacent to the retinal pigment epithelium, which in turn is attached to the inside of the eye ball. The stacked-disc structure of the detector portion of the cell allows for very high efficiency. Rods are much more common than cones, with about 100 million rod cells compared to 7 million cone cells. Like cones, rod cells have a synaptic terminal, an inner segment, and an outer segment. The synaptic terminal forms a

neg: Metamerism (color) Metamerism (color) In colorimetry, metamerism is a perceived matching of the colors with different (nonmatching) spectral power distributions. Colors that match this way are called metamers. A spectral power distribution describes the proportion of total light given off (emitted, transmitted, or reflected) by a color sample at each visible wavelength; it defines the complete information about the light coming from the sample. However, the human eye contains only three color receptors (three types of cone cells), which means that all colors are reduced to three sensory quantities, called the tristimulus values. Metamerism occurs because each type of cone responds to

neg: Retina bipolar cell on to the ganglion cells directly or indirectly (via amacrine cells). Unlike most neurons, bipolar cells communicate via graded potentials, rather than action potentials. Bipolar cells receive synaptic input from either rods or cones, or both rods and cones, though they are generally designated rod bipolar or cone bipolar cells. There are roughly 10 distinct forms of cone bipolar cells, however, only one rod bipolar cell, due to the rod receptor arriving later in the evolutionary history than the cone receptor. In the dark, a photoreceptor (rod/cone) cell will release glutamate, which inhibits (hyperpolarizes) the ON bipolar cells and excites

neg: Adaptation (eye) dark because channels would re-open and allow for the cell to slightly depolarize. Inhibition by neurons also affects activation in synapses. Together with the bleaching of a rod or cone pigment, merging of signals on ganglion cells are inhibited, reducing convergence. Alpha adaptation, "i.e.", rapid sensitivity fluctuations, is powered by nerve control. The merging of signals by virtue of the diffuse ganglion cells, as well as horizontal and amacrine cells, allow a cumulative effect. Thus that area of stimulation is inversely proportional to intensity of light, a strong stimulus of 100 rods equivalent to a weak stimulus of 1,000 rods.

neg: European mole one would expect to see. Instead they all have one uniform shape with three distinct features: Studies have shown that "T. europaea" does have photopic vision, contrary to popular belief that all moles are blind. Two cone opsins have been found in the eyes of "T. europaea" but their function is still under investigation. In a study of the mole eyes it was found that "Talpa" withdraws when exposed to a flashlight and it can also perform light/dark discrimination tasks. The cone cells in the eye are unlikely to provide high-resolution vision but they could allow a detection of movement

neg: Optics less sensitive to the overall intensity of light, but come in three varieties that are sensitive to different frequency-ranges and thus are used in the perception of colour and photopic vision. Cone cells are highly concentrated in the fovea and have a high visual acuity meaning that they are better at spatial resolution than rod cells. Since cone cells are not as sensitive to dim light as rod cells, most night vision is limited to rod cells. Likewise, since cone cells are in the fovea, central vision (including the vision needed to do most reading, fine detail work such as

neg: Mammalian eye synapse. Differences between the rhodopsin and the iodopsins is the reason why cones and rods enable organisms to see in dark and light conditions — each of the photoreceptor proteins requires a different light intensity to break down into the constituent products. Further, synaptic convergence means that several rod cells are connected to a single bipolar cell, which then connects to a single ganglion cell by which information is relayed to the visual cortex. This convergence is in direct contrast to the situation with cones, where each cone cell is connected to a single bipolar cell. This divergence results in

neg: Rattlesnake to more accurately visualize their surroundings in low levels of light. Research conducted recently on the molecular mechanism of this ability suggests the temperature sensitivity of these pit organs is closely linked to the activity of transient receptor potential ankyrin 1, a temperature-sensitive ion channel saturated in the pit membrane. Rattlesnake eyes, which contain a large number of rod cells, are well adapted to nocturnal use. However, rattlesnakes are not exclusively nocturnal, and their vision is more acute during daylight conditions. Rattlesnakes also possess cone cells, which means they are capable of some form of color vision. The rattlesnake eye

neg: Light light with wavelength weighted with respect to a standardised model of human brightness perception. Photometry is useful, for example, to quantify Illumination (lighting) intended for human use. The SI units for both systems are summarised in the following tables. The photometry units are different from most systems of physical units in that they take into account how the human eye responds to light. The cone cells in the human eye are of three types which respond differently across the visible spectrum, and the cumulative response peaks at a wavelength of around 555 nm. Therefore, two sources of light which produce

neg: Scanning laser ophthalmoscopy these cells can also be calculated to determine the axial orientation of retinal cells in the living subject. This represents a major benefit over typical histological examination of small numbers of donated human eyes. AOSLO has also revealed significant decreases in foveal cone packing density for myopic eyes in comparison to emmetriopic eyes. This difference has been hypothesized to originate from a natural decrease in cone density with the increase in eye axial length associated with myopia. Abnormalities in photoreceptor structure in regions damaged by macular dystrophy have additionally been imaged by AOSLO. In these subjects, a dark area has

neg: Toothed whale and cone cells, meaning they can see in both dim and bright light. They do, however, lack short wavelength-sensitive visual pigments in their cone cells, indicating a more limited capacity for colour vision than most mammals. Most toothed whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas, and a tapetum lucidum; these adaptations allow for large amounts of light to pass through the eye, and, therefore, a very clear image of the surrounding area. In water, a whale can see around ahead of itself, but they have a smaller range above

neg: Chromostereopsis axis, red will appear closer. The reverse effect is observed when the pupillary center is nasal to the visual axis. Recent research has attempted to extend the basis for the traditional chromostereoptic theory, including work done by Stiles and Crawford. In 1933, Stiles and Crawford accidentally discovered that the light sensitivity differed for rays entering through center versus those entering from peripheral regions of the eye. The efficiency of the rays is less when the rays enter via the peripheral region because the shape of the cone cells that collect the incident quanta are different from cone receptors in the

neg: Color photography physicist James Clerk Maxwell. It is based on the Young-Helmholtz theory that the normal human eye sees color because its inner surface is covered with millions of intermingled cone cells of three types: in theory, one type is most sensitive to the end of the spectrum we call "red", another is more sensitive to the middle or "green" region, and a third which is most strongly stimulated by "blue". The named colors are somewhat arbitrary divisions imposed on the continuous spectrum of visible light, and the theory is not an entirely accurate description of cone sensitivity. But the simple description

neg: Mammalian eye light, which allows an organism to see color. The shift from cone vision to rod vision is why the darker conditions become, the less color objects seem to have. The differences between rods and cones are useful; apart from enabling sight in both dim and light conditions, they have further advantages. The fovea, directly behind the lens, consists of mostly densely packed cone cells. The fovea gives humans a highly detailed central vision, allowing reading, bird watching, or any other task which primarily requires staring at things. Its requirement for high intensity light does cause problems for astronomers, as they

neg: Averted vision technique is called scope rocking, which is done by simply moving the telescope back and forth slightly to move the object around in the field of view. This technique is based on the fact that the visual system is more sensitive to motion than to static objects. Averted vision works because there are virtually no rods (cells which detect dim light in black and white) in the fovea: a small area in the center of the eye. The fovea contains primarily cone cells, which serve as bright light and color detectors and are not as useful during the night. This

neg: Primary color The Natural Color System is also directly inspired by the psychological primaries. There are numerous competing primary colour systems throughout history. Scholars and scientists engaged in debate over which hues best describe the primary color sensations of the eye. Thomas Young proposed red, green, and violet as the three primary colors, while James Clerk Maxwell favoured changing violet to blue. Hermann von Helmholtz proposed "a slightly purplish red, a vegetation-green, slightly yellowish, and an ultramarine-blue" as a trio. In modern understanding, human cone cells do not correspond precisely to a specific set of primary colors, as each cone type responds

neg: Double cone (biology) the double cones. Double cone (biology) Double cones (DCs), known as twin cones when the two members are the same, are two cone cells (colour detecting photoreceptors) joined together that may also be coupled optically/electrically. They are the most common type of cone cells in fish, reptiles and birds, and are present in most vertebrates, though they have been noted as absent in placental mammals (including humans), elasmobranches and catfish. There are many gap junctions between the cells of fish double cones. Their function, if they have any unique function compared to single cones, is largely unknown; proposed uses include

neg: Double cone (biology) Double cone (biology) Double cones (DCs), known as twin cones when the two members are the same, are two cone cells (colour detecting photoreceptors) joined together that may also be coupled optically/electrically. They are the most common type of cone cells in fish, reptiles and birds, and are present in most vertebrates, though they have been noted as absent in placental mammals (including humans), elasmobranches and catfish. There are many gap junctions between the cells of fish double cones. Their function, if they have any unique function compared to single cones, is largely unknown; proposed uses include achromatic (non-colour vision)

neg: National Eye Institute that looked at the bacteria in the gut and how it protects the natural flora. Findings from studies suggest that this characteristic may be similar to how immune cells attack the eye in autoimmune eye diseases such as uveitis. Autoimmune uveitis is an inflammatory eye disease where the immune cells attack proteins in the eye. By studying how immune cells, also known as T cells, attack other parts of the body, researchers may gain further information on how the T cells are activated in the eye. It will also allow researchers to understand the disease better and develop treatments or

neg: White all the buildings of contemporary architect Richard Meier, such as his museum in Rome to house the ancient Roman Ara Pacis, or Altar of Peace, are stark white, in the tradition of Le Corbusier. Light is perceived by the human visual system as white when the incoming light to the eye stimulates all three types of color sensitive cone cells in the eye in roughly equal amounts. Materials that do not emit light themselves appear white if their surfaces reflect back most of the light that strikes them in a diffuse way. In 1666, Isaac Newton demonstrated that white light

neg: Amacrine cell amacrine cells though, are marked by the glycine transporter GlyT1. One very well characterized glycinergic amacrine cell is the AII amacrine cells. These cells are present in the INL. One importance function of the AII amacrine cells is that they capture cellular input from rod bipolar cells and redistribute it to cone bipolar cells using the synaptic endings of cone bipolar cells as adaptors Around 15% of amacrine cells are neither GABAergic or glycinergic. These amacrine cells are sometimes known as nGnG amacrine cells, and it is thought that transcription factors that act on progenitors decide the fate of amacrine

neg: Tawny owl is probably inaccurate by at least a factor of 10. The owl's actual visual acuity is only slightly greater than that of humans, and any increased sensitivity is due to optical factors rather than to greater retinal sensitivity; both humans and owl have reached the limit of resolution for the retinas of terrestrial vertebrates. Adaptations to night vision include the large size of the eye, its tubular shape, large numbers of closely packed retinal rods, and an absence of cone cells, since rod cells have superior light sensitivity. There are few coloured oil drops, which would reduce the light intensity.

neg: Amacrine cell stratification. Like horizontal cells, amacrine cells work laterally, but whereas horizontal cells are connected to the output of rod and cone cells, amacrine cells affect the output from bipolar cells, and are often more specialized. Each type of amacrine cell releases one or several neurotransmitters where it connects with other cells. They are often classified by the width of their field of connection, which layer(s) of the stratum in the IPL they are in, and by neurotransmitter type. Most are inhibitory using either gamma-Aminobutyric acid or glycine as neurotransmitters. As mentioned above, there are several different ways to divide the