Surgeons take pains to avoid injuring nerves in and around surgical sites—a stray cut could lead to muscle weakness, pain, numbness, or even paralysis. In delicate operations like prostate removal, for instance, accidentally damaging nerves can lead to incontinence or erectile dysfunction. Scientists at University of California San Diego have announced a new method for lighting up nerves in the body with fluorescent peptides, which could act as markers to keep surgeons away.