Abstract
Purpose:
The aim of the study was to investigate the spatio-temporal contrast sensitivity functions (CSFs) of adult zebrafish (Danio rerio) under photopic and scotopic conditions by assessing the optokinetic reflex. To date, in zebrafish, CSFs were only measured cursory at photopic light levels. Detailed CSFs help to better understand the visual system of zebrafish, e.g. whether it is tuned to spatial frequency, speed or temporal frequency. Furthermore, CSFs allow the identification of ideal test conditions for visual functions.
Methods:
Contrast sensitivity threshold was measured using a modified commercially available optomotor device (OptoMotry, Cerebral Mechanics, Lethbridge, AB, Canada). After dark-adaption, contrast was changed several times in a stair case procedure to identify the threshold. Spatio-temporal CSFs were performed at luminance levels between 1.8 log cd m-2 and -6.3 log cd m-2.
Results:
We present detailed CSFs of adult zebrafish, both at photopic and scotopic light levels. Contrast sensitivity of adult zebrafish increased with increasing luminance. The vision of adult zebrafish is tuned to speed and spatial frequencies but not to temporal frequencies.
Conclusions:
Zebrafish are often used as an animal model in visual research, amongst others because of its cone-rich retina and easy accessible visual system. We present the first measurements of spatio-temporal CSFs in zebrafish under photopic and scotopic conditions. In contrast to mice - but not to humans - vision is tuned to spatial frequency and speed under both conditions. The CSFs will facilitate the analysis of genetically modified fish or pharmacological effects on the visual system.
Keywords: 478 contrast sensitivity •
641 perception •
524 eye movements: recording techniques