Color Processing in Zebrafish Retina

Abstract

Zebrafish (Danio rerio) is a model organism for vertebrate developmental processes and, through a variety of mutant and transgenic lines, various diseases and their complications. Some of these diseases relate to proper function of the visual system. In the US, the National Eye Institute indicates >140 million people over the age of 40 have some form of visual impairment. The causes of the impairments range from refractive error to cataract, diabetic retinopathy and glaucoma, plus heritable diseases such as retinitis pigmentosa and color vision deficits. Most impairments directly affect the retina, the nervous tissue at the back of the eye. Zebrafish with long or short-wavelength color blindness, altered retinal anatomy due to hyperglycemia, high intraocular pressure, and reduced pigment epithelium are all used, and directly applicable, to study how these symptoms affect visual function. However, many published reports describe only molecular/anatomical/structural changes or behavioral deficits. Recent work in zebrafish has documented physiological responses of the different cell types to colored (spectral) light stimuli, indicating a complex level of information processing and color vision in this species. The purpose of this review article is to consolidate published morphological and physiological data from different cells to describe how zebrafish retina is capable of complex visual processing. This information is compared to findings in other vertebrates and relevance to disorders affecting color processing is discussed.

What the Zebrafish’s Eye Tells the Zebrafish’s Brain: Retinal Ganglion Cells for Prey Capture and Colour Vision

“…Colour opponency in the retinal output is often taken as a hallmark of circuits for colour vision (Baden and Osorio, 2019). Previous behavioural and physiological experiments have clearly demonstrated tetrachromatic colour vision including colour constancy in species of cyprinids (Dörr and Neumeyer, 2000;Krauss and Neumeyer, 2003;Neumeyer, 1992) including key aspects in zebrafish (Meier et al, 2018). This implies that there should be at least three spectrally distinct mechanisms of opponency in the visual system.…”

“…Third, most investigations into the function of zebrafish visual circuits have relied on long-wavelength light stimulation to limit interference with fluorescence imaging systems (Bollmann, 2019). However, like many surface-dwelling teleost fish (Baden and Osorio, 2019;Champ et al, 2016;Neumeyer, 1992), zebrafish have rich tetrachromatic colour vision (Krauss and Neumeyer, 2003;Meier et al, 2018;Orger and Baier, 2005), and spectrally diverse functions dominate both their outer (Klaassen et al, 2016) and inner retinal circuits (Connaughton and Nelson, 2010;Meier et al, 2018;Zimmermann et al, 2018). In fact, wavelength is strongly associated with specific behaviours in zebrafish.…”

Modality-specific circuits for skylight orientation in the fly visual system

“…Identifying the cellular elements forming these circuits and understanding how their synaptic connections enable these circuits to perform their specific computational function remains a major challenge 1 . Both in mammals and invertebrate models, the visual system has long served as a powerful system for investigating the neuronal basis of specific computations covering different aspects of visual perception, like color vision [2][3][4] , the detection of looming [5][6][7] or moving stimuli 8 . In recent years, the quickly growing arsenal of molecular-genetic tools available in Drosophila has been used to dissect the neuronal circuits underlying specific visual behaviors via the cell type-specific visualization and/or manipulation of neuronal activity.…”

<strong>&shy;</strong>The Retinal Basis of Vertebrate Color Vision

“…In goldfish, spectrophotometry of cone outer segments gives respective sensitivity maxima of 623 nm 537 nm 447 nm and 356 nm (Palacios et al 1998). Zebrafish have shorter wavelength peaks at about 565 nm, 477 nm, 415 nm and 360 nm (Meier et al 2018), but gene duplication allows these fishlike many othersto express different variants in a given cone (Bowmaker 2008, Chinen et al 2003, Parry et al 2005).…”

“…As a result, different cone types receive different spectral-contrast surround inhibition. For example, zebrafish have at least three cone-selective and one rod-selective HCs with spectrally mono-, bi-and triphasic response properties (Meier et al 2018) (Fig. 3c).…”