This news release is available in German.
Our eyes not only enable us to recognise objects; they also provide us with a continuous stream of information about our own movements. Whether we run, turn around, fall or sit still in a car the world glides by us and leaves a characteristic motion trace on our retinas. Seemingly without effort, our brain calculates self-motion from this "optic flow". This way, we can maintain a stable position and a steady gaze during our own movements. Together with biologists from the University of Freiburg, scientists from the Max Planck Institute of Neurobiology in Martinsried near Munich have now discovered an array of new types of neurons, which help the brain of zebrafish to perceive, and compensate for, self-motion.
When we jog through a forest, the image of the trees appears to move backwards across our retina. This occurs for both eyes in the same direction. If, however, we turn about our own axis, the trees appear to rotate around us. For one eye, this rotation goes from the outside in, and for the other one it goes from the inside out. Our brain processes such large-scale movements in the visual environment, the "optic flow", so that when jogging, for example, we can estimate our speed correctly and do not constantly stumble.
The human brain is, of course, not unique in being able to perceive optic flow. Fish that live in rivers and streams use this capability, for example, to prevent themselves from drifting in the current. Based on the optic flow, the fish corrects its passive drifting through its own swimming. How and where the fish brain carries out these calculations was not previously known.
"We wanted to know how the compensatory movements are triggered and by which neurons," explains Herwig Baier. Together
|Contact: Dr. Herwig Baier|