Electropathic residue was a reading that could be present in humanoid brains. It characterized Iresine Syndrome when accompanied by depressed histamine counts; when unaccompanied by such counts and localized in the thalamus, it could indicate Ullian telepathic memory invasion. It could also be caused by some twenty-two non-medical agents, including ferrazene, hylanatine, dardilion, chrysimite, and manzene, all of which could be scanned by ships' sensors. (TNG: "Violations" )