Fig. 7. Results of two methods for characterizing tuning properties of Knollenorgan electroreceptors. Frequency responses are shown for a single Knollenorgan in either type I (A; specimen 3) or type II (B; specimen 5). Red plots show threshold tuning curves. Black plots show magnitude spectra of revcor filters (computed for the same units; plotted upside down; not smoothed in these cases). Each spectrum is aligned vertically to the corresponding tuning curve for comparison.