Further Analysis of Sensory Coding in Electroreceptors of Electric Fish

Abstract

A new category of sensory transducers, electroreceptors, was to be inferred from the work of Lissmann^l and Lissmann and Machine^2,3 and was directly demonstrated by Hagiwara et al.,⁴⁻⁸ Szabo and Fessard,^9,10 and Szabo^ll in electric fish. Three fresh-water families, the Gymnotidae from tropical America and the Gymnarchidae and Mormyridae from tropical Africa, with many species, all discharge low-voltage pulses from small electric organs more or less continuously into the water, apparently useful in detecting objects, cavities, other fish, and as social signals to each other. The diversity of form of discharge is important. Some gymnotids and perhaps all mormyrids discharge at low (ca. 0–5/sec), irregular frequencies, rising (to 30–100/sec) with excitement. Other gymnotids and the only known gymnarchid discharge at high (300–>1000/sec), regular, species-characteristic, and nearly invariant frequencies. Several gymnotids are intermediate, including the subject of this communication.

Aided by grants from the National Institutes of Health, National Science Foundation, Office of Naval Research, and Air Force Office of Scientific Research.