Electrical synapses between AII amacrine cells in the retina: Function and modulation. 2012

Espen Hartveit, and Margaret Lin Veruki
University of Bergen, Department of Biomedicine, Bergen, Norway. espen.hartveit@biomed.uib.no

Adaptation enables the visual system to operate across a large range of background light intensities. There is evidence that one component of this adaptation is mediated by modulation of gap junctions functioning as electrical synapses, thereby tuning and functionally optimizing specific retinal microcircuits and pathways. The AII amacrine cell is an interneuron found in most mammalian retinas and plays a crucial role for processing visual signals in starlight, twilight and daylight. AII amacrine cells are connected to each other by gap junctions, potentially serving as a substrate for signal averaging and noise reduction, and there is evidence that the strength of electrical coupling is modulated by the level of background light. Whereas there is extensive knowledge concerning the retinal microcircuits that involve the AII amacrine cell, it is less clear which signaling pathways and intracellular transduction mechanisms are involved in modulating the junctional conductance between electrically coupled AII amacrine cells. Here we review the current state of knowledge, with a focus on the recent evidence that suggests that the modulatory control involves activity-dependent changes in the phosphorylation of the gap junction channels between AII amacrine cells, potentially linked to their intracellular Ca(2+) dynamics. This article is part of a Special Issue entitled Electrical Synapses.

UI MeSH Term Description Entries
D009415 Nerve Net A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction. Neural Networks (Anatomic),Nerve Nets,Net, Nerve,Nets, Nerve,Network, Neural (Anatomic),Networks, Neural (Anatomic),Neural Network (Anatomic)
D012160 Retina The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent. Ora Serrata
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000221 Adaptation, Ocular The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed) Light Adaptation,Adaptation, Light,Adaptations, Light,Adaptations, Ocular,Light Adaptations,Ocular Adaptation,Ocular Adaptations
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014794 Visual Fields The total area or space visible in a person's peripheral vision with the eye looking straightforward. Field, Visual,Fields, Visual,Visual Field
D017629 Gap Junctions Connections between cells which allow passage of small molecules and electric current. Gap junctions were first described anatomically as regions of close apposition between cells with a narrow (1-2 nm) gap between cell membranes. The variety in the properties of gap junctions is reflected in the number of CONNEXINS, the family of proteins which form the junctions. Gap Junction,Junction, Gap,Junctions, Gap
D017630 Connexins A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions. Connexin,Connexin Complex Proteins,Gap Junction Proteins,Gap Junction Channel Proteins,Gap Junction Protein,Junction Protein, Gap,Junction Proteins, Gap
D054351 Electrical Synapses Specialized junctions between NEURONS which connect the cytoplasm of one neuron to another allowing direct passage of an ion current. Gap Junctions, Neuronal,Neuronal Gap Junctions,Synapses, Electrical,Synapses, Electrotonic,Electrotonic Synapses,Electrical Synapse,Electrotonic Synapse,Gap Junction, Neuronal,Junction, Neuronal Gap,Junctions, Neuronal Gap,Neuronal Gap Junction,Synapse, Electrical,Synapse, Electrotonic
D017948 Retinal Rod Photoreceptor Cells Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination. Photoreceptors, Rod,Retinal Rod Cells,Rod Photoreceptors,Rods (Retina),Retinal Rod,Retinal Rod Cell,Retinal Rod Photoreceptor,Retinal Rod Photoreceptors,Rod Photoreceptor Cells,Cell, Retinal Rod,Cell, Rod Photoreceptor,Cells, Retinal Rod,Cells, Rod Photoreceptor,Photoreceptor Cell, Rod,Photoreceptor Cells, Rod,Photoreceptor, Retinal Rod,Photoreceptor, Rod,Photoreceptors, Retinal Rod,Retinal Rods,Rod (Retina),Rod Cell, Retinal,Rod Cells, Retinal,Rod Photoreceptor,Rod Photoreceptor Cell,Rod Photoreceptor, Retinal,Rod Photoreceptors, Retinal,Rod, Retinal,Rods, Retinal

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