Take crack cocaine. Particularly in the early days of the policy, ninety percent of the people being arrested were black, even though they didn't use the drug at higher rates and even though their numbers in the general population are so low. How could that be? The thing is, you place all your resources in communities of color. And if you do that, you're going to arrest black people.

Much of the early work focused on dopamine and we were really looking for rewarding sorts of effects and sure enough, we only found that. But you can destroy the main dopamine-producing structures of the brain and you can still get an animal to self-administer drugs like cocaine.

I am glad that people are trying to have a rational conversation about drugs.

The policy that received more attention particularly in the past decade and a half or so has been the US cocaine policy, the differential treatment of crack versus powder cocaine and question is how my research impacted my view on policy. Clearly that policy is not based on the weight of the scientific evidence. That is when the policy was implemented, the concern about crack cocaine was so great that something had to be done and congress acted in the only way they knew how, they passed policy and that's what a responsible society should do.

One of the things that has happened is that our drug laws have been institutionalized now. If you want to say that somebody's a bad person in a movie or in a television show or something about that, you say they sell drugs or they use drugs.

Dopamine makes up less than one percent of the brain's neurotransmitters. It's a small portion. Dopamine is released when people are happy, angry, stressed. So it's really hard to call this specific neurotransmitter "the pleasure neurotransmitter."

If you're a member of a despised group, look out! They'll find a drug and associate you with its use. There are a lot of people in the gay community using methamphetamine and paying taxes and going to work and doing well.