Summary: 1128 nature neuroscience · volume 3 no 11 · november 2000
Zebrafish larvae innately begin responding to moving stimuli short-
ly after hatching. In their optomotor response, which is elicited by
large moving stimuli presented from below or the side1,2, larvae
swim in the direction of perceived motion. The distance they trav-
el in a given time indicates the effectiveness of the stimulus. By
observing the response of many larvae to computer-animated dis-
plays, we could determine which attributes of a moving stimulus
the zebrafish visual system detects.
If luminance-defined features drift smoothly or jump in space,
they can produce strong sensations of motion. A number of pro-
posed models explain how motion information can be extracted.
In a simple model, a point-to-point comparison is made between
the luminance pattern and a spatially displaced copy of the pattern
that was seen a short time before3. The displacement that gives the
best fit tells the brain the direction and speed of movement. A more
complex strategy is to look at the Fourier motion energy in the visu-
al scene4. A number of biologically plausible methods of calculating
this motion energy have been proposed4,5,6.