Amacrine cells differentially balance zebrafish color circuits in the central and peripheral retina

• Published in: Cell reports (Cambridge) Vol. 42; no. 2; p. 112055
• Main Authors: Wang, Xinwei, Roberts, Paul A., Yoshimatsu, Takeshi, Lagnado, Leon, Baden, Tom
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.02.2023; Elsevier
• Subjects: amacrine cell; bipolar cell; color vision; CP: Neuroscience; inhibition; retina; zebrafish; amacrine cell; retina; CP: Neuroscience; inhibition; bipolar cell; zebrafish; color vision
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2023.112055

The vertebrate inner retina is driven by photoreceptors whose outputs are already pre-processed; in zebrafish, outer retinal circuits split “color” from “grayscale” information across four cone-photoreceptor types. It remains unclear how the inner retina processes incoming spectral information while also combining cone signals to shape grayscale functions. We address this question by imaging the light-driven responses of amacrine cells (ACs) and bipolar cells (BCs) in larval zebrafish in the presence and pharmacological absence of inner retinal inhibition. We find that ACs enhance opponency in some bipolar cells while at the same time suppressing pre-existing opponency in others, so that, depending on the retinal region, the net change in the number of color-opponent units is essentially zero. To achieve this “dynamic balance,” ACs counteract intrinsic color opponency of BCs via the On channel. Consistent with these observations, Off-stratifying ACs are exclusively achromatic, while all color-opponent ACs stratify in the On sublamina. [Display omitted] •Zebrafish bipolar cells inherit color-opponent signals from the outer retina•ACs destroy this opponency in some BCs but simultaneously rebuild it in others•On balance, ACs do therefore not notably alter color processing in BCs•Some ACs therefore preserve incoming information that would otherwise be lost Wang et al. reveal how zebrafish retinal amacrine cells simultaneously destroy and rebuild color information in bipolar cells so that the net change is essentially zero. The authors posit that the role of some inhibitory networks is not to sharpen neural representation but to rebuild information that would otherwise be lost.