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. Author manuscript; available in PMC: 2017 Oct 27.
Published in final edited form as: J Physiol Paris. 2016 Oct 27;110(3 Pt B):200–215. doi: 10.1016/j.jphysparis.2016.10.005

Fig. 6.

Fig. 6

Comparison of harmonic content in the waveform of the EOD and AM (beat) generated by two interacting EODs 10 Hz apart in frequency. Power spectrum of A) an A. albifrons EOD and B) a S. terminalis EOD. Both EODs were stretched and re-sampled to 800 Hz. Representative EODs are shown in the upper-right corner of each panel. F1, F2, F3, and F4 show the power spectrum peaks corresponding to the fundamental frequency, second harmonic, third harmonic, and fourth harmonic, respectively. The height of those peaks (in dB) indicates the power in each harmonic. We calculated F2-F1 and F3-F1 to quantify differences in waveform. The same analysis was done for C) the AM of two A. albifrons EODs combined at a 10 Hz DF and D) the AM of two S. terminalis EODs combined at a 10 Hz DF. The AM is denoted by the top and bottom traces on the combined EODs shown in the upper-right corner of panels C and D. Note the difference in the timescale of the EOD vs. AM traces and in the frequency scale on the X-axis of the power spectra in A vs. C and B vs. D. For A. albifrons, both the EOD waveform and the AM generated by the interacting EODs are relatively sinusoidal, and there was much more power in F1 than in F2 or F3. Conversely, for S. terminalis, the EODs and the AM are both relatively complex, and there was more power in F2 and F3 than in F1. Note that dB is a logarithmic scale. E) Relationship between F2-F1 in the EOD and F2-F1 of the AM of interacting EODs across individuals from twelve apteronotid species. This analysis arranged each fish according to waveform, with the most sinusoidal EODs on the left and the most complex EODs on the right. F2-F1 of the EOD is strongly correlated with F2-F1 of the AM in species with waveforms of intermediate complexity. Insets show representative waveforms for A. albifrons (nearly sinusoidal), A. devenanzii (moderately complex) and S. terminalis (complex). F) Relationship between F3-F1 in the EOD and F3-F1 of the AM of interacting EODs across the same fish from twelve apteronotid species. A pattern similar to that of F2-F1 emerges for the comparison of F3-F1 of the EOD to F3-F1 of the AM.