Communication in the weakly electric fish Sternopygus macrurus. I. The neural basis of conspecific EOD detection.
There is a sexual dimorphism in the frequency of the quasi-sinusoidal electric organ discharge (EOD) of Sternopygus macrurus, with males, on average, an octave lower. EODs are detected by tuberous electroreceptor organs, which exhibit V-shaped frequency tuning with maximal sensitivity near the fish's own EOD frequency. This would seem to limit the ability of a fish to detect the EODs of opposite-sex conspecifics. However, electroreceptor tuning has always been based on single-frequency stimulation, while actual EOD detection involves the addition of a conspecific EOD to the fish's own. In the present study, recordings were made from single electroreceptive units while the fish were stimulated with pairs of sine waves: one (S1) representing the fish's own EOD added to a second (S2) representing a conspecific EOD. T unit response was easily predicted by assuming that the electroreceptor acts as a linear filter in series with a threshold-sensitive spike initiator. P unit response was more complex, and unexpectedly high sensitivity was found for frequencies of S2 well displaced from the fish's EOD frequency. For both P and T units, detection thresholds for S2 were much lower when added to S1, than when presented alone.
Fleishman
L J
LJ
Department of Zoology, University of Texas, Austin 78712.
D000819:Animal Communication; D000818:Animals; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000294:innervation / Q000502:physiology*; D005260:Female; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D009474:Neurons / Q000502:physiology*