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Encyclopedia > Photosensitive ganglion cell

The Photosensitive Ganglion Cell is an output cell of the retina whose axons make up the optic nerve. a labratory in Rhode Island is labelling retinal ganglion cells by retrograde transport from the brain; analyzing in vitro their light responses, intrinsic membrane properties and synaptic pharmacology using the whole-cell patch clamp method; and revealing their morphology with intracellular dyes. A cell is a single unit or compartment, enclosed by a border or wall. ... Human eye cross-sectional view. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, which conducts electrical impulses away from the neurons cell body or soma. ... The optic nerve is the nerve that transmits visual information from the retina to the brain. ... In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. ... Wiktionary has a definition of: In vitro In vitro (Latin: within glass) means within a test tube, or, more generally, outside a living organism or cell. ...


Recently, a novel ganglion cell in the rat retina has been discovered that is intrinsically photosensitive. These ganglion cells exhibit robust light responses even when all influences from classical photoreceptors (rods and cones) are blocked, either by applying pharmacological agents or by dissociating the ganglion cell from the retina. These photosensitive ganglion cells seem likely to serve as photoreceptors for the photic synchronization of circadian rhythms, the mechanism that allows us to overcome jet lag. They project to the circadian pacemaker of the brain, the suprachiasmatic nucleus of the hypothalamus. Their temporal kinetics, threshold, dynamic range, and spectral tuning all match known properties of the synchronization or "entrainment" mechanism. These photosensitive ganglion cells innervate various other brain targets, such as the midbrain pupillary control center, and apparently contribute to a host of behavioral responses to ambient lighting conditions. These findings help to explain why circadian and pupillary light responses persist in mammals, including humans, with profound disruption of rod and cone function. Ongoing experiments are designed to elucidate the phototransduction mechanism, including the identity of the photopigment and the nature of downstream signaling pathways. Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... Human eye cross-sectional view. ... Photosensitivity is the amount to which an object reacts upon receiving photons of light. ... A Ganglion Cell (or sometimes called a gangliocyte) is a type of Neuron located in the retina that receives visual information from bipolar cells; its axons give rise to the optic nerve. ... Human eye cross-sectional view. ... Photosensitivity is the amount to which an object reacts upon receiving photons of light. ... The circadian rhythm is a name given to the internal body clock that regulates the (roughly) 24 hour cycle (Determined by the light input from Photosensitive Ganglion Cell[s]) of biological processes in animals and plants. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... The word Rod may have one of the following meanings. ... A cone is a basic geometrical shape: see cone (geometry). ...


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