Since humans harnessed the power of electricity at the turn of the 19th century, we haven't looked back. But some fish coopted electric fields to their own advantage well before Benjamin Franklin went kite flying in a thunderstorm. Mormyrid fish use electric fields to perceive the world around them. How they interpret distortions in their self-generated electric fields to negotiate their way around has puzzled Angel Caputi and his colleagues for several years. Knowing that Gnathonemus petersii generate their field with an electrically discharging organ, Caputi and his international team decided to measure the fish's electrical activity while simultaneously recording their neurological responses to a variety of objects, to see how Gnathonemus begins to interpret the complex currents resulting from electric field disturbance ().
The team found that metal objects placed in the fish's electric field distorted the current at the fish's surface, increasing the current in the centre of the object's electrical image while depleting the current in the surrounding area. Caputi and his team describe the profile of the current shift as a `Mexican hat' shape, with a high cap and turned up brim.
Recording signals from the receptors that detect the fluctuating surface current, the team describes that the intensity of the electrical stimulus is coded by the amplitude and number of neural responses sent by receptors to the electrosensory lobe where the fish processes the signals. Caputi and his team explain that as `each individual receptor encodes information from the whole scene... the brain must process the electrical image presented over the whole sensory surface'.
