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Encyclopedia > Bipolar cell of the retina
Retinal Bipolar Cells
Retina. Bipolar cells are shown in red.
Location Retina (Inner Nuclear Layer)
Function Convey gradients between photoreceptor cells to retinal ganglion cells
Morphology bipolar
Presynaptic connections Rods , cones and Horizontal Cells
Postsynaptic connections Retinal ganglion cells and Amacrine cells


As a part of the retina, the bipolar cell exists between photoreceptors (rod cells and cone cells) and ganglion cells. They act to, directly or indirectly, transmit signals from the photoreceptors to the ganglion cells. Axial organization of the retina (from Cajal, 1911) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Human eye cross-sectional view. ... The inner nuclear layer or layer of inner granules is made up of a number of closely packed cells, of which there are three varieties, viz. ... In vector calculus, the gradient of a scalar field is a vector field which points in the direction of the greatest rate of change of the scalar field, and whose magnitude is the greatest rate of change. ... A photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eyes retina that is capable of phototransduction. ... The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ... Plan of retinal neurons. ... A ganglion cell (or sometimes called a gangliocyte) is a type of neuron located in the retina that receives visual information from photoreceptors via various intermediate cells such as bipolar cells, amacrine cells, and horizontal cells. ... Amacrine cell Retinal cell interneuron interacting at the Inner Plexiform Layer (IPL), the second synaptic retinal layer where bipolar cells and ganglion cells synapse. ... Human eye cross-sectional view. ... A photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eyes retina that is capable of phototransduction. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ... A ganglion cell (or sometimes called a gangliocyte) is a type of neuron located in the retina that receives visual information from photoreceptors via various intermediate cells such as bipolar cells, amacrine cells, and horizontal cells. ...

Contents

Overview

Bipolar cells are so-named as they have a central body from which two sets of processes arise. They can synapse with either rods or cones (but not both), and they also accept synapses from horizontal cells. The bipolar cells then transmit the signals from the photoreceptors or the horizontal cells, and pass it on to the ganglion cells through Localized Graded Potentials. Plan of retinal neurons. ...


Specification

Bipolar cells Accept synapses from either rods or cones, but not both, and they are designated rod bipolar or cone bipolar cells respectively. 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.



Furthermore, they can be categorized into two different groups, ON and OFF, based on how they react to glutamate released by photoreceptor cells. When light hits a photoreceptor cell, the photoreceptor depolarizes, and releases the glutamate. An ON bipolar cell will react to this change by depolarizing. An OFF bipolar cell will react to this change by hyperpolarizing. Glutamate is the anion of glutamic acid. ... In biology, depolarization is the event a cell undergoes when its membrane potential grows more positive with respect to the extracellular solution. ...


Functionality

Bipolar cells effectively transfer information from rods and cones to ganglion cells. The horizontal cells and the amacrine cells complicate matters somewhat. The horizontal cells introduce lateral inhibition and give rise to the center-surround inhibition which is apparent in retinal receptive fields. The amacrine cells also introduce lateral inhibition, however, its role is not yet well understood. Plan of retinal neurons. ... The receptive field of a sensory neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron. ...



The mechanism for producing the center of a bipolar cell's receptive field is well known: direct innervation of the photoreceptor above it, either through a metabotropic (ON) or ion otropic (OFF) receptor. However, the mechanism for producing the monochromatic surround of the same receptive field is under investigation. While it is known that an important cell in the process is the horizontal cell, the exact sequence of receptors and molecules is as of yet unknown. The receptive field of a sensory neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron. ... A photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eyes retina that is capable of phototransduction. ... Metabotropic receptor is a transmembrane receptor, which starts some intracellular biochemical cascade after its activation by an agonistic ligand. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... Plan of retinal neurons. ... In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of an organism. ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ...


See also

Photoreceptors are light-sensitive proteins involved in the function of photoreceptor cells. ... Plan of retinal neurons. ... Amacrine cell Retinal cell interneuron interacting at the Inner Plexiform Layer (IPL), the second synaptic retinal layer where bipolar cells and ganglion cells synapse. ... A ganglion cell (or sometimes called a gangliocyte) is a type of neuron located in the retina that receives visual information from photoreceptors via various intermediate cells such as bipolar cells, amacrine cells, and horizontal cells. ...

References

Nicholls, John G.; A. Robert Martin, Bruce G. Wallace, Paul A. Fuchs (2001). From Neuron to Brain. Boston, Massachusetts: Sinauer Associates, Inc. ISBN 0-87893-439-1. 


Masland, Richard H (2001). "The Fundamental Plan of the Retina". Nature Neuroscience 4 (9). 


External links

  • MeSH Retinal+bipolar+cells
  • Diagram at mcgill.ca

  Results from FactBites:
 
Eye and Retina (1414 words)
The retina is a seven-layered structure involved in signal transduction.
In the mature retina it is pushed directly up next to the neural retina, which came from the inner layer of the optic cup.
This complex receptive field is created by the interneurons of the retina: the bipolar cells and the horizontal cells, primarily.
Retina - Wikipedia, the free encyclopedia (1949 words)
The retina is a thin layer of cells at the back of the eyeball of vertebrates and some cephalopods; it is the part of the eye which converts light into nervous signals.
The central retina is cone-dominated and the peripheral retina is rod-dominated.
One response, from on cells, is to increase the rate of firing to increases in light intensity in the centre of the receptive field.
  More results at FactBites »

 
 

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