Through genetic tweaking, researchers at the School of Medicine have made fruit flies walk, jump and fly on command—by flashing a light at them. The scientists inserted rat ion channels into nerve cells that control flies’ escape movements, then injected the flies with a chemical that would activate the ion channels when exposed to light. Gero A. Miesenböck, M.D., associate professor of cell biology at the medical school, who led the study that appeared in the journal Cell in April, said that the research offers a new way to learn how nerve cells govern behavior.