A Compass in the Dark (IMAGE) Helmholtz Munich (Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)) Caption Analyzing zebrafish and medaka fish allowed the researchers to measure brain activity during magnetic stimulation. Credit © Westmeyer/Helmholtz Zentrum München Usage Restrictions None License Licensed content 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.