| Amacrine cell | |
|---|---|
 |
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| Location | INL of the retina |
| Function | inhibitory or neuromodulatory interneurons |
| Neurotransmitter | GABA, glycine, DA, or 5-HT |
| Morphology | Varies |
| Presynaptic connections | Bipolar cells |
| Postsynaptic connections | Bipolar cells and Ganglion cells |
Amacrine cells are interneurons in the retina. An interneuron (also called association neuron, local circuit neuron or relay neuron) is a neuron which connects Afferent neurons and Efferent The vertebrate retina is a light sensitive part inside the inner layer of the Eye. Amacrine cells are responsible for 70% of input to retinal ganglion cells. Bipolar cells, which are responsible for the other 30% of input to retinal ganglia, are regulated by amacrine cells.
Contents |
Overview
Amacrine cells operate at the inner plexiform layer (IPL), the second synaptic retinal layer where bipolar cells and ganglion cells synapse. The inner plexiform layer is made up of a dense reticulum of minute Fibrils formed by the interlacement of the Dendrites of the Ganglion cells with those A bipolar cell is a type of Neuron which has two extensions Bipolar cells are specialized sensory neurons for the transmission of special senses A ganglion cell (more correctly a retinal ganglion cell or RGC) is a type of Neuron typically located near the inner surface of the Retina Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands There are about 40 different types of amacrine cells, most lacking axons. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell Like horizontal cells, amacrine cells work laterally affecting the output from bipolar cells, however, their tasks are often more specialized. Each type of amacrine cell connects with a particular type of bipolar cell, and generally has a particular type of neurotransmitter. See Chemical synapse for an introduction to concepts and terminology used in this article One such population, AII, 'piggybacks' rod bipolar cells onto the cone bipolar circuitry. It connects rod bipolar cell output with cone bipolar cell input, and from there the signal can travel to the respective ganglion cells.
They are 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 GABA or glycine as neurotransmitters. Gamma-aminobutyric acid (GABA is the chief inhibitory Neurotransmitter in the Mammalian Central nervous system. Glycine (abbreviated as Gly or G) is the Organic compound with the formula NH2CH2COOH See Chemical synapse for an introduction to concepts and terminology used in this article
Functionality
Relatively little is known of the functional roles of the Amacrine cells. Amacrine cells with extensive dendritic trees are thought to contribute to inhibitory surrounds by feedback at both the bipolar cell, and ganglion cell levels. In this role they are considered to supplement the action of the horizontal cells. Amacrine cells give much more input to M (Magnocellular) ganglion cells than to P (Parvocellular) ganglion cells.
Other forms of Amacrine cell are likely to play modulatory roles, allowing adjustment of sensitivity for photopic and scotopic vision. The AII Amacrine cell (also known as the Rod amacrine cell) is a mediator of signals from rod cells under scotopic conditions.
See also
References
- Nicholls, John G. A photoreceptor, or photoreceptor cell, is a specialized type of Neuron (nerve cell found in the Eye 's Retina that is capable of Horizontal cells are the laterally interconnecting neurons in the outer plexiform layer of the Retina of mammalian eyes As a part of the Retina, the bipolar cell exists between photoreceptors ( Rod cells and Cone cells and Ganglion cells They act to A ganglion cell (more correctly a retinal ganglion cell or RGC) is a type of Neuron typically located near the inner surface of the Retina ; 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 RH (2001). "The fundamental plan of the retina". Nat. Neurosci. 4 (9): 877–86. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 11528418.
External links
- Webvision amacrine cell article
- MeSH A08.663.358.050
- Eye Brain and vision book Hubel D (1988) Eye Brain and Vision, whole book available online. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books
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