Possible involvement of the ampullary electroreceptor system in detection of frequency-modulated electrocommunication signals in Eigenmannia.
Behavioral and electrophysiological experiments were conducted to examine whether frequency-modulated electrocommunication signals are detected by the ampullary electroreceptor system in Eigenmannia. First, frequency-modulated electric organ discharges were found to contain a low-frequency component that could be detected by the ampullary system. Second, fish were successfully trained to distinguish a frequency-modulated signal, which contained a low-frequency component as in natural signals, from an artificial signal in which the low-frequency component was eliminated but still modulated in frequency. Subsequently, the trained fish responded without reinforcement to a low-frequency sinusoidal signal which mimicked the low-frequency component in the frequency-modulated signal, suggesting that the fish used the ampullary system to detect frequency modulation. Finally, physiological recording from ampullary afferent fibers demonstrated that they respond to frequency-modulated signals as predicted from the signal's low-frequency component. Electrophysiological study also showed that detection of frequency modulation by the ampullary system is immune to the presence of other constant electric organ discharges.
Naruse
M
M
Department of Biology, University of Virginia, Charlottesville 22903, USA.
Kawasaki
M
M
D000200:Action Potentials / Q000502:physiology; D000819:Animal Communication; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000166:cytology / Q000294:innervation / Q000502:physiology*; D004594:Electrophysiology; D009420:Nervous System / Q000166:cytology; D009424:Nervous System Physiological Phenomena; D009475:Neurons, Afferent / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology