Starburst Amacrine Cell
Starburst amacrine cells, also referred to as SAC, SBAC, or cholinergic neurons, are a specific subset of amacrine cells present in the retina. Generally speaking, amacrine cells function by affecting the output from bipolar cells. Each of the ~40 subtypes of amacrine cells connects with a particular type of bipolar cell and secretes a particular neurotransmitter. Starburst amacrine cells are noteworthy for being the only cells in the retina to secrete two different kinds of neurotransmitter: the inhibitory neurotransmitter GABA (gamma-aminobutyric acid) as well as the excitatory neurotransmitter acetylcholine (ACh).[2]
Starburst amacrine cells have been shown to preferentially connect to direction-selective ganglion cells (DSGCs), where they provide the main source of inhibition and are essential in the computation of direction selectivity.[3] The asymmetry of the connections between starburst amacrine cells and DSGCs is the prevailing model for how direction selectivity is computed. At least some asymmetry in the connections between these two cell types has been demonstrated,[4] but the exact mechanism of direction selective computation has yet to be determined.
Contents
Physiology
Visual response properties
Cellular biophysics
Anatomy
Location
Shape
Connections
Molecules
History
In 1976, it was first discovered that there were cells in the rabbit retina that secreted acetylcholine. The most likely candidates were bipolar cells and amacrine cells. Later that same year, it was shown that ganglion cells formed the postsynaptic component of that connection.
Open Questions
References
- ↑ Keeley,P.W.etal.Dendriticspreadandfunctionalcoverageofstarburstamacrine cells. J. Comp. Neurol. 505, 539–546 (2007).
- ↑ O’Malley, D. M., Sandell, J. H. & Masland, R. H. Co-release of acetylcholine and GABA by the starburst amacrine cells. J. Neurosci. 12, 1394–1408 (1992).
- ↑ Yoshida, K. et al. A key role of starburst amacrine cells in originating retinal directional selectivity and optokinetic eye movement. Neuron 30, 771–780 (2001).
- ↑ Briggman, K.L., Helmstaedter, M. & Denk, W. Wiring specificity in the direction-selectivity circuit of the retina. Nature (in the press) (2011).
- ↑ reference 1976
