Behavioral Evidence and Supporting Electrophysiological Observations for Electroreception in the Blind Cave Salamander, <i>Proteus anguinus </i>(Urodela)

Conditioning experiments revealed that Proteus perceives a back-and-forth moving (approximately 1 Hz) direct-current field and its polarity. Minimum behavioral thresholds occurred at a current density of 0.15 microA/cm2, corresponding to a voltage gradient of 0.5 mV/cm. Recordings from afferent nerve fibers showed that ampullary electroreceptors in Proteus respond as do other nonteleost receptors, i.e. with an increase in discharge rate to cathodal current and a decrease to anodal current (threshold: approximately 1 mV/cm).