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Role of ACh-GABA Cotransmission in Detecting Image Motion and Motion Direction

2010; Cell Press; Volume: 68; Issue: 6 Linguagem: Inglês

10.1016/j.neuron.2010.11.031

1097-4199

Seung‐Hoon Lee, Kyongmin Kim, Zhimin Zhou,

Neuroinflammation and Neurodegeneration Mechanisms

Summary Starburst amacrine cells (SACs) process complex visual signals in the retina using both acetylcholine (ACh) and gamma-aminobutyric acid (GABA), but the synaptic organization and function of ACh-GABA corelease remain unclear. Here, we show that SACs make cholinergic synapses onto On-Off direction-selective ganglion cells (DSGCs) from all directions but make GABAergic synapses onto DSGCs only from the null direction. ACh and GABA were released differentially in a Ca 2+ level-specific manner, suggesting the two transmitters were released from different vesicle populations. Despite the symmetric cholinergic connection, the light-evoked cholinergic input to a DSGC, detected at both light onset and offset, was motion- and direction-sensitive. This input was facilitated by two-spot apparent motion in the preferred direction but supressed in the null direction, presumably by a GABAergic mechnism. The results revealed a high level of synaptic intricacy in the starburst circuit and suggested differential, yet synergistic, roles of ACh-GABA cotransmission in motion sensitivity and direction selectivity.