Fig. 8
Power spectra density curves show that an intact lateral line allowed fish to make fewer yet more temporally variable changes in relative linear and angular movement.
Because frequency and period are inversely related, the low frequency peaks to left of the periodograms indicate cycles with longer periods, and vice versa The amplitude of the peaks indicates the spectral density, or the number of movement events at a given frequency that occurred during the experiment. The peaks with the greatest amplitude indicate the fundamental or dominant frequencies of fluctuation in the periodicity data. The frequency and amplitude of three most dominant peaks were summed to calculate the net shifts in frequency and power. Relative to controls (gray, n = 248 fish), lesioned fish (blue = CuSO4, n = 204 fish; green = neomycin, n = 222 fish) had a net downshift in the three dominant frequencies of a relative movement, b velocity, and c acceleration and a net upshift in d mean body angle of larval zebrafish during rheotaxis. For the dominant frequencies of e mean resultant length, there was a net downshift and upshift for CuSO4- and neomycin-treated fish, respectively. Furthermore, relative to lateral line intact fish, the peaks of lesioned fish are clustered into fewer peaks of greater amplitude over a relatively narrow range, which indicates that lateral line ablation increased the number yet reduced the temporal variation of changes in movement. |