An internal current source yields immunity of electrosensory information processing to unusually strong jamming in electric fish.
The electric organ of a fish represents an internal current source, and the largely isopotential nature of the body interior warrants that the current associated with the fish's electric organ discharges (EODs) recruits all electroreceptors on the fish's body surface evenly. Currents associated with the EODs of a neighbor, however, will not penetrate all portions of the fish's body surface equally and will barely affect regions where the neighbor's current flows tangentially to the skin surface. The computational mechanisms of the jamming avoidance response (JAR) in Eigenmannia exploit the uneven effects of a neighbor's EOD current to calculate the correct frequency difference between the two interfering EOD signals even if the amplitude of a neighbor's signal surpasses that of the fish's own signal by orders of magnitude. The particular geometry of the fish's own EOD current thus yields some immunity against the potentially confusing effects of unusually strong interfering EOD currents of neighbors.
Heiligenberg
W
W
Neurobiology Unit, Scripps Institution of Oceanography, UCSD, La Jolla 92093-0202.
Kawasaki
M
M
D000818:Animals; D004555:Electric Fish / Q000502:physiology*; D004557:Electric Organ / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology; D008465:Mechanoreceptors / Q000502:physiology; D009949:Orientation / Q000502:physiology; D011712:Pyramidal Tracts / Q000166:cytology / Q000502:physiology; D012867:Skin / Q000294:innervation; D012879:Skin Physiological Phenomena