Ectopic retinal ON bipolar cell synapses in the OFF inner plexiform layer: contacts with dopaminergic amacrine cells and melanopsin ganglion cells.

ABSTRACT: A key principle of retinal organization is that distinct ON and OFF channels are relayed by separate populations of bipolar cells to different sublaminae of the inner plexiform layer (IPL). ON bipolar cell axons have been thought to synapse exclusively in the inner IPL (the ON sublamina) onto dendrites of ON-type amacrine and ganglion cells. However, M1 melanopsin-expressing ganglion cells and dopaminergic amacrine (DA) cells apparently violate this dogma. Both are driven by ON bipolar cells, but their dendrites stratify in the outermost IPL, within the OFF sublamina. Here, in the mouse retina, we show that some ON cone bipolar cells make ribbon synapses in the outermost OFF sublayer, where they costratify with and contact the dendrites of M1 and DA cells. Whole-cell recording and dye fill

SUBMITTER: Dumitrescu ON 

PROVIDER: S-EPMC3296562 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature