The eye of a zebrafish larva can distinguish between prey and predator
Red or green? Small or large? Fast or slow? Humans and animals rely on their visual organs to classify objects in their environment. Decisions about how we best respond to moving objects in our environment are often made very quickly and unconsciously. The size of a moving object is obviously an important criterion. The rapid speed of a response suggests that specialised neural circuits in the visual system are responsible for recognising important object properties. If they are activated, they trigger the "fight" or "flight" signal in the brain. Scientists at the Max Planck Institute for Medical Research in Heidelberg have now shed light on how such circuits, which are likely to be crucial in classifying objects by size, function in the brain of the zebrafish larva.