title: Role of ACh-GABA cotransmission in detecting image motion and motion direction.
abstract: 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 mechanism. 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.
authors.affiliation: Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT 06510, USA.
authors.forename: Seunghoon
authors.initials: S
authors.lastname: Lee
authors.forename: Kyongmin
authors.initials: K
authors.lastname: Kim
authors.forename: Z Jimmy
authors.initials: ZJ
authors.lastname: Zhou
mesh_terms: D000109:Acetylcholine / Q000502:physiology*; D025042:Amacrine Cells / Q000502:physiology; D000818:Animals; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011817:Rabbits; D012160:Retina / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine