Courtship communication and hearing in an African electric fish

Abstract

Among sound‐producing fishes, Pollimyrus isidori is of particular interest because of its unusually large repertoire of sounds (5), and because its ears (sacculi) are specialized for sound pressure detection. Males use temporally patterned sounds for courting females, and the male's sonic behavior is elicited by electric signals from the female. The courtship sounds are composed of trains of clicks, and inter‐click interval (ICI) distinguishes the different sounds. The processing of these temporal features is being explored in the brain (mesencephalon) with single unit electrophysiology. The P. isidori auditory system is most sensitive to sounds in the region where amplitude spectrum for the communication sounds peaks (235 Hz), and at a distance of a meter from a sound‐producing male (i.e., about 20 body lengths) many neurons would be at least 20–30 dB above threshold. Most neurons are broadly tuned (Q10dB⩽2), and precisely represent temporal periodicities in their phase‐locked activity. A subpopulation of neurons shows an increased probability of response when the ICI is close to that of one of the courtship sounds. These neurons probably play an important role in the brain's analysis of temporal features of communication sounds. [Work supported by NIH NRSA DC00020‐02 and CDR P50 DC00293‐06.]