Research article beyond the Jamming Avoidance Response: Weakly electric fish respond to the envelope of social electrosensory signals

Ent studies have shown that central nervous system neurons in weakly electric fish respond to artificially constructed ctrosensory envelopes, but the behavioral relevance of such stimuli is unclear. Here we investigate the possibility that social text creates envelopes that drive behavior. When Eigenmannia virescens are in groups of three or more, the interactions ween their pseudo-sinusoidal electric fields can generate 'social envelopes'. We developed a simple mathematical prediction how fish might respond to such social envelopes. To test this prediction, we measured the responses of E. virescens to stimuli sisting of two sinusoids, each outside the range of the Jamming Avoidance Response (JAR), that when added to the fish's n electric field produced low-frequency (below 10 Hz) social envelopes. Fish changed their electric organ discharge (EOD) quency in response to these envelopes, which we have termed the Social Envelope Response (SER). In 99% of trials, the ction of the SER was consistent with the mathematical prediction. The SER was strongest in response to the lowest initial elope frequency tested (2 Hz) and depended on stimulus amplitude. The SER generally resulted in an increase of the envelope quency during the course of a trial, suggesting that this behavior may be a mechanism for avoiding low-frequency social elopes. Importantly, the direction of the SER was not predicted by the superposition of two JAR responses: the SER was ensitive to the amplitude ratio between the sinusoids used to generate the envelope, but was instead predicted by the sign of difference of difference frequencies.