Vision to action

Prey capture and looming-evoked escape

A small object moving in the visual field of larval zebrafish is perceived as a potential prey target. This primitive stimulus triggers a well-defined sequence of behavioral responses in the fish, composed of coordinated eye, fin and tail movements, which finally lead to a prey capture strike. How are such simple, but behaviorally relevant stimuli processed in the brain to result in a stereotyped motor output? How do fish navigate in a complex and rich environment and how do they respond to the most salient stimulus to survive?

To answer these questions, we are following the visual pathway from the retina (red) to the tectum (green), the visual processing center in the fish brain, and its output neurons (orange) to premotor regions in the hindbrain. We are combining functional imaging, optogenetics and single cell reconstructions to identify circuit components along this path, which are responsible for sensorimotor transformations.

Optomotor and optokinetic response

A set of space-filling black-and-white stripes that move around the fish evoke two characteristic behaviors. When the stripes move around the fish, the animal’s eyes make jerky movements from side to side in pursuit of the drifting grating (optokinetic response). When the stripes drift alongside the fish, then the fish swim with the perceived direction of movement (optomotor response). We have discovered that the brain distinguishes between these types of motion with the help of specialized neurons in the pretectum (the fish’s accessory optic system). The aim of the optic flow group is to understand the wiring diagram of the pretectal area serving this task.