Sensitization is the increase in sensitivity to a drug or natural reward after continued use. Sensitization is a manifestation of neuroplastic changes in response to repeated exposure, and some researchers have hypothesized that it is a behavioral correlate of increased craving and development of dependence. Put simply: continused use creates powerful, motivating memories related to one's addiction. When activated by cues these memories stir cravings while increasing dopamine. Sensitized pathways remain long after the addict quits using.