Neuroimaging and behavioral research in humans also provide evidence of the addictive potential of sweet foods. Palatable foods (including high-sugar foods) and drugs of abuse activate similar brain systems (e.g., dopamine and opioid systems). Obese and substance-dependent participants exhibit similar patterns of neural response to cues (i.e., increased activation in motivation and reward areas) and consumption (i.e., decreased activation in control and reward areas) of palatable foods and drugs, respectively. Furthermore, healthy-weight individuals who consume ice cream more frequently display in the fMRI scanner a lower reward-related response in the brain when consuming a milkshake. This may reflect the development of tolerance to the hedonic effects of ice cream analogous to the way that people develop tolerance to the rewarding effects of drugs of abuse.