Bistratified ganglion cell can refer to either of two kinds of retinal ganglion cells whose cell body is located in the ganglion cell layer of the retina, the small-field bistratified ganglion cell, also known as small bistratified cell (SBC), and the large-field bistratified ganglion cell or large bistratified cell (LBC). [1] [2]
Bistratified cells receive their input from bipolar cells and amacrine cells. The bistratified cells project their axons through the optic nerve and optic tract to the koniocellular layers in the lateral geniculate nucleus (LGN), synapsing with koniocellular cells. Koniocellular means "cells as small as dust"; their small size 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.
The macula or macula lutea is an oval-shaped pigmented area near the center of the retina of the human eye and some other animalian eyes. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
Color vision is the ability of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit. Colors can be measured and quantified in various ways; indeed, a person's perception of colors is a subjective process whereby the brain responds to the stimuli that are produced when incoming light reacts with the several types of cone cells in the eye. In essence, different people see the same illuminated object or light source in different ways.
The visual system is the part of the central nervous system which gives organisms the ability to process visual detail as sight, as well as enabling the formation of several non-image photo response functions. It detects and interprets information from visible light to build a representation of the surrounding environment. The visual system carries out a number of complex tasks, including the reception of light and the formation of monocular representations; the buildup of a nuclear binocular perception from a pair of two dimensional projections; the identification and categorization of visual objects; assessing distances to and between objects; and guiding body movements in relation to the objects seen. The psychological process of visual information is known as visual perception, a lack of which is called blindness. Non-image forming visual functions, independent of visual perception, include the pupillary light reflex (PLR) and circadian photoentrainment.
The lateral geniculate nucleus is a relay center in the thalamus for the visual pathway. It receives a major sensory input from the retina. The LGN is the main central connection for the optic nerve to the occipital lobe, particularly the primary visual cortex. In humans, each LGN has six layers of neurons alternating with optic fibers.
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.
The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina.
The receptive field of an individual sensory neuron is the particular region of the sensory space in which a stimulus will modify the firing of that neuron. This region can be a hair in the cochlea or a piece of skin, retina, tongue or other part of an animal's body. Additionally, it can be the space surrounding an animal, such as an area of auditory space that is fixed in a reference system based on the ears but that moves with the animal as it moves, or in a fixed location in space that is largely independent of the animal's location. Receptive fields have been identified for neurons of the auditory system, the somatosensory system, and the visual system.
Magnocellular cells, also called M-cells, are neurons located within the Adina magnocellular layer of the lateral geniculate nucleus of the thalamus. The cells are part of the visual system. They are termed "magnocellular" since they are characterized by their relatively large size compared to parvocellular cells.
As a part of the retina, bipolar cells exist between photoreceptors and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells.
The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye.
A koniocellular cell is a neuron with a small cell body that is located in the koniocellular layer of the lateral geniculate nucleus (LGN) in primates, including humans.
Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye. The presence of ipRGCs were first noted in 1923 when rodless, coneless mice still responded to a light stimulus through pupil constriction, suggesting that rods and cones are not the only light sensitive neurons in the retina. It wasn't until the 1980s that advancements in research on these cells began. Recent research has shown that these retinal ganglion cells, unlike other retinal ganglion cells, are intrinsically photosensitive due to the presence of melanopsin, a light sensitive protein. Therefore they constitute a third class of photoreceptors, in addition to rod and cone cells.
The retinohypothalamic tract (RHT) is a photic neural input pathway involved in the circadian rhythms of mammals. The origin of the retinohypothalamic tract is the intrinsically photosensitive retinal ganglion cells (ipRGC), which contain the photopigment melanopsin. The axons of the ipRGCs belonging to the retinohypothalamic tract project directly, monosynaptically, to the suprachiasmatic nuclei (SCN) via the optic nerve and the optic chiasm. The suprachiasmatic nuclei receive and interpret information on environmental light, dark and day length, important in the entrainment of the "body clock". They can coordinate peripheral "clocks" and direct the pineal gland to secrete the hormone melatonin.
Mammals normally have a pair of eyes. Although mammalian vision is not so excellent as bird vision, it is at least dichromatic for most of mammalian species, with certain families possessing a trichromatic color perception.