so the dopamine neurons projected to the preparental cortex, the amygdala and a few other brain structures, these the most important ones. it turned out that the manipulation of the dopamine neurotransmission by giving dopamine antagonists and other substances would modify reward-seeking behavior. and in particular it was found out like by people like roy wise and associates and other people that the electrical stimulation for brain reward was partly related to the dopamine neurons. in fact stimulating the dopamine neurons meant the animal would repeat that electrical stimulation. it was like getting a reward. >> rose: tell us about addiction. >> at the essence, of course, of addiction is why do people take drugs? and they take drugs because they want to feel good. and drugs make you feel good. and they make you feel good because they hijack these reward systems. all of the drugs of abuse that we know that can make people... that increase dopamine in the pleasure centers of the brain and that is believed to actually be crucial for producing the rewarding effects and to ultimately lead to t