“In addiction, this means that because being addicted escalates wanting more than liking, the drug experience gets deeply carved into your memory. Anything you can associate with achieving a drug high, you will. As a result, when you try to quit, everything from a spoon (you could use it to prepare drugs) to a street (this is where the dealer lives!) to stress (when I feel like this, I need drugs) can come to drive craving. Desire fuels learning, whether it is normal learning or the pathological “overlearning” that occurs in addiction. You learn what interests you with ease because desire motivates. In contrast, it’s far more difficult to learn something you don’t want to understand or care to comprehend. Berridge and Robinson’s research also helps resolve another paradox: If dopamine signifies pleasure, then the brain should become less and less responsive to it as tolerance to a drug develops. But while tolerance clearly does occur, the opposite result is also seen in the brain. As I took cocaine, paranoia began to set in at lower and lower doses—not higher ones. The summer of 1988, it also took increasingly less drug to achieve the state of heart-pounding anxiety and mortal dread that I experienced so frequently. Neuroscientist Marc Lewis described his experience of this effect in his addiction memoir this way: “I kept pumping [cocaine] into my vein, this non-sterile solution, until my reeling consciousness, nausea, racing heart, and bloated capillaries told me that death was near. Later that night, I begged myself to stop.… But the urge would not relent.”