Psychophysics And Genetics Of Zebrafish Visual Behavior

A central goal of neuroscience is to understand the neural basis of behavior. The zebrafish is a vertebrate model system that allows behavior to be studied using both systems and molecular genetic approaches. Here we present a psychophysical and genetic analysis of optomotor behavior in zebrafish larvae. By applying psychophysical methods developed for primates to zebrafish we have demonstrated than motion detection in zebrafish uses mechanisms that are broadly similar to humans. The larvae are susceptible to visual illusions that indicate that they detect Fourier motion energy in visual scenes. They also respond to non-Fourier motion, an ability that is believed to depend on visual cortex in humans. Different visual behaviors in the fish use different chromatic information. The optomotor response, in particular, is colorblind and pools signals from longer wavelength cones, while excluding shorter wavelength inputs. Motion processing seems to be functionally similar between higher and lower vertebrates despite large differences in neuroanatomy. Using an automated assay, we have conducted a large-scale genetic screen for recessive mutants affecting the optomotor response. Testing these mutants with a battery of behavioral assays allows us to categorize them into motor and visual system mutants, as well as some that are specific to the optomotor response. Many have normal visual system anatomy, but some are missing specific cell-types or have defects in axon target selection.