Comparison of Discharges Among Fishes With and Without the Evolved Brain (image) Washington University in St. Louis Share Print E-Mail Caption In the top group of fishes, species in the genus Paramoryrops that has the complex signal-processing brain, discharges have changed quickly, resulting in dramatically different pulses among closely related species. In the bottom group of fishes, species in the genus Petrocephalus whose midbrain is more simply structured, all of the species have similar pulses. The difference arises because the top group has the anatomical features needed to exploit the signal space -- such as the anatomy needed to make different pulses and the sensory and analytical ability to perceive small differences in pulse shape. Credit Sebastien Lavoue, Carl Hopkins, John Sullivan and Matthew Arnegard Usage Restrictions Please credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.