I always have been interested in the visual system, first as an orthoptist and later as a psychophysiologist. One of the functions of the visual system I am especially interested in is color vision. I have investigated color discrimination behaviorally in goldfish as well as in men. Those studies confirmed, among other things, that goldfish is a good model for investigating the human visual system.
To understand what kind of information processing takes place in the visual system, one has to distinguish the processing in the eye from the one in the brain. At this moment, my work in the Retinal Signal Processing Unit consists in characterizing the way in which horizontal cells communicate with cones. This communication is thought to play a role in color constancy, an aspect of color vision. Iris Fahrenfort performs patch-clamp measurements on cone photoreceptors and I measure the characteristics of the horizontal cells using intracellular sharp electrodes. Together, these measurements give a quantitative and qualitative description of the communication between cones and horizontal cells.
Recently I have started to study the optokinetic nystagmus of zebrafish. We use the optokinetic response to test color and contrast vision in normal zebrafish and in zebrafish with defects in their retinal wiring.