 - Relapse to drug abuse often happens in the presence of stimuli that are associated with previous drug use, also known as cues. Drug-taking behavior appears to be partly controlled by such cues. Some research suggests that cue-induced craving states are responsible for drug use and relapse, but other research suggests that cues can control drug taking without conscious craving or even awareness. Researchers are interested in using functional magnetic resonance imaging fMRI to study how individuals respond to drug-related cues and how these cues affect craving on a conscious or unconscious level. 