Neural Circuit Contributing to the Formation of the Receptive Surround
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Formation of the center-surround organization of the receptive field is one of the most important functions of the vertebrate retina, and many studies have been reported on its mechanism. Since the historical finding of  in turtle cones, it has been widely accepted that the feedback signal from the horizontal cell (HC) is responsible for the formation of the antagonistic surround response of cone photoreceptors. Accumulating evidence has suggested that the feedback from HC to cones is mediated by y-aminobutyric acid (GABA); HCs are GABAergic, they release GABA upon depolarization, and GABA receptors are concentrated at the cone terminal. On the other hand, there are number of reports criticizing the GABA hypothesis of HC-cone feedback.