Figure 8. Stability of group motor activity.

The graphs show group mean instantaneous velocity (y-axis) against time (x-axis). The mean displacement of 48 zebrafish was plotted for each successive frame transition (grey line). The average of this value over a moving 30-frame window was superimposed (black line) to illustrate the underlying trend. A: Consistent motor activity over an hour of recording; stable recordings facilitate numerical analysis and comparison of experimental groups. B: Insufficient habituation at the start of the assay results in changes to baseline activity as zebrafish acclimatize to experimental conditions. C: Extraneous stimuli such as temperature variations, noise, and visual stimuli cause instability in baseline activity that can obscure responses to experimental stimuli or differences between experimental samples. D: Group mean velocity/time graphs are also helpful for illustrating responses to stimuli, such as motor responses to changes in ambient illumination shown here. Approval to conduct these experiments was obtained from the University of Pittsburgh Institutional Animal Care and Use Committee.