Figure 1. Larval swimming speed depends on OMR grating speed.

Relevant kinematic variables which describe larval zebrafish swimming are plotted against grating speed over a range of 0-40 mm/s. (A) Schematic of experimental rig for freely-swimming larvae. High-speed video was acquired from above with drifting gratings projected on a screen below the arena, and larvae illuminated with IR light. (B) Image processing involved background subtraction, determination of the global maxima (green point), and tail curvature (Experimental Procedures, Supplemental Materials). Scale bar = 2 mm. (C) Instantaneous swimming speed vs. grating speed. Traces are aligned such that zero on the x-axis is the initiation of the first bout in the direction of the stimulus motion. For data to the right of the black line (left of this line indicates orienting maneuvers the larva uses to align its body with the axis of motion of the grating), we see the difference in swimming speed as a function of grating speed, but also the timing during which this swimming speed varies with respect to initiation of grating motion. Panels (D-I) represent data from 52,938 bouts from 45 freely swimming larvae. (D) Average swimming speed during trial (mm/s) vs. grating speed. (E) Average bout distance (mm) vs. grating speed. (F) Average bout duration (ms) vs. grating speed. (G) Average tail-beat frequency (TBF) elicited during a bout (Hz) vs. grating speed. (H) Average interbout duration (ms) vs. grating speed. (I) Latency (ms) vs. grating speed. Error bars indicate SEM.