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Type 2 wide‐field amacrine cells in TH :: GFP mice show a homogenous synapse distribution and contact small ganglion cells
Author(s) -
Brüggen Bianca,
Meyer Arndt,
Boven Franziska,
Weiler Reto,
Dedek Karin
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12813
Subject(s) - inhibitory postsynaptic potential , excitatory postsynaptic potential , amacrine cell , neuroscience , postsynaptic potential , inner plexiform layer , synapse , biology , microbiology and biotechnology , parasol cell , green fluorescent protein , retina , chemistry , giant retinal ganglion cells , retinal ganglion cell , biochemistry , gene , receptor
In vertebrate retinas, wide‐field amacrine cells represent a diverse class of interneurons, important for the extraction of selective features, like motion or objects, from the visual scene. Most types of wide‐field amacrine cells lack dedicated output processes, whereas some types spatially segregate outputs from inputs. In the tyrosine hydroxylase ( TH )::green fluorescent protein ( GFP ) mouse line, two types of GFP ‐expressing wide‐field amacrine cells have been described: dopaminergic type 1 and γ‐aminobutyric acid‐ergic type 2 cells ( TH 2). TH 2 cells possess short and long radial processes stratifying in the middle of the inner plexiform layer, where they collect excitatory and inhibitory inputs from bipolar cells and other amacrine cells, respectively. Although it was shown that these inputs lead to ON – OFF light responses, their spatial distribution along TH 2 cell processes is unknown. Also, the postsynaptic targets of TH 2 cells have not been identified so far. Here, we analysed the synapse distribution of these cells in TH :: GFP mice and show that they form a weakly coupled network. Electrical synapses (made of connexin36) and chemical (excitatory and inhibitory) synapses are uniformly distributed along TH 2 dendrites, independent of dendrite length or distance from soma. Moreover, we reveal that TH 2 cells contact at least two types of small ganglion cells; one of them is the W3 cell, a ganglion cell sensitive to object motion. Contacts were often associated with markers of inhibitory synapses. Thus, TH 2 wide‐field amacrine cells likely provide postsynaptic inhibition to W3 ganglion cells and may contribute to object‐motion detection in the mouse retina.