Arts & Sciences

Hormone alters electric fish’s signal-canceling trick

African fish called mormyrids communicate using pulses of electricity. (Photo: Tsunehiko Kohashi)

During the rainy breeding season, the underwater “conversation” among electric fish changes. Fish revved up to make a match broadcast slightly different signals to advertise their presence and identify compatible mates.

New research from Washington University in St. Louis shows that the hormone testosterone — which naturally triggers male electric fish to elongate the electric pulses they send out during the breeding season — also alters a system in the fish’s brain that enables the fish to ignore its own electric signals. The study by biologists Matasaburo Fukutomi, PhD and Bruce Carlson, PhD in Arts & Sciences is published in Current Biology.

All animals, from electric fish to elephants, need to have ways to discriminate between the signals that they share themselves versus signals or stimuli from others. Accurately perceiving and acting upon information from others can make all the difference for reproduction and survival.

The electric fish known as mormyrids send out electric pulses as signals; they also have developed a way to ignore or block their own messages. A system called corollary discharge inhibits the fish’s sensory perception for a brief, well-defined period of time after it releases an electric pulse — allowing it to prioritize messages from others, such as potential mates.

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