Research studies indicate that sites and pathways located in the limbic system and focused on appetite drive states appear to be responsible for normal and pathological craving for alcohol and other addicting drugs. Animal studies have identified neurosubstrates and neurotransmitterers associated with behavioral models of addiction and have substantiated pathological craving for alcohol and drugs in humans. Repetitive administration of alcohol and drugs appears to affect hedonic homeostasis of the appetitive drives leading to the hedonic alleostasis where negative reinforcement exceeds positive returns despite continued drug use. Neuroimaging studies have concentrated on areas in the brain related to reward or reinforcement of alcohol and drug use, but the technique can be used to find support for a neurosubstrate to distinguish normal craving or liking from pathological craving or wanting a drug. Identifying the neurobasis of wanting a drug long after not liking it is central to understanding pathological craving and loss over control over drug use in addiction in humans. Neuroimaging is currently the only method directly to visualize sites for craving in the human brain. The analysis concludes that neuroimaging techniques will provide methods not possible in animals for studying addiction in humans. 75 references (Author abstract modified)