Production of aggressive electrocommunication signals to progressively realistic social stimuli in male Apteronotus leptorhynchus.

Kent D. Dunlap and Jonah Larkins-Ford

Department of Biology, Trinity College, Hartford, CT 06106

Brown ghost knife fish, Apteronotus leptorhynchus, produce a continuous electric organ discharge (EOD) that they use for communication. While interacting aggressively, males also emit brief EOD modulations termed chirps. The simplicity of this behavior and its underlying neural circuitry has made it an important model system in neuroethology. Chirping is typically assayed by confining fish in a tube ("chirp chamber") and presenting them with sine wave electrical stimuli that partially mimic EODs of other fish. We presented male fish with progressively more realistic social stimuli to examine whether some of the stimulus complexities during dyadic interaction influence the production of chirps. In a chirp chamber, fish chirped less to a recording of an EOD containing chirps than to a recording of an EOD alone and to sine wave stimuli. Free-swimming fish chirped more to stimulus fish than to sine wave stimuli presented through electrodes. Fish chirped more when interacting directly than when interacting across a perforated barrier. Together, these studies demonstrate that the presence of chirps, electric field complexity, and/or non-electric social stimuli are important in eliciting chirp production in brown ghosts.