What is more important for the survival of the human species than empathy and compassion—than actually being able to look at another human being, even if they look different than you, even if they have a different belief system than you, what is more important than actually understanding that 98% of your life is very similar?

Truth be told, I have had a bad trip or two in the '70s ... I have no idea what a suicidal depression feels like where you are experiencing such a darkness, such a lack of hope, that a rational decision is to end one's life. And I think the closest I ever came to that experience was a bad trip on LSD.

The addictive liability of a substance is directly correlated with two aspects of dopamine: how much dopamine is released in the accumbens and the kinetics of the dopamine release—as you said, how rapidly it's released.

Yes, a single administration of a drug of abuse, like cocaine, like morphine, can cause relatively—several days, several weeks—of changes in the connections on to dopamine neurons and on to the neurons in the nucleus accumbens. That does not mean these changes are permanent or irreversible.

If you take one mouse, and in an ethical way, you put it in pain... and you let what's known as the bystander mouse just hang out with the mouse that's in pain for one hour, just one hour, the bystander mouse who has experienced no physical injury whatsoever will manifest behaviors indicating it is now in pain.

I think it's perhaps a somewhat over-simplification of how people conceptualize dopamine's role in the brain is even though its major important role is for it to be active and released during highly reinforcing experiences—like sex, like really good food, like drugs of abuse—it also can get activated in subdivisions of this system during painful stimuli and during aversive stimuli.

Your listeners may think that scientists are these geeky individuals wearing white coats with no passion or emotion, and nothing could be further from the truth. The most successful scientists I know are pretty passionate and pretty intense about what they're working on and driven.

What we found was that oxytocin action in the nucleus accumbens was indeed important for promoting sociability, probably for promoting the reinforcing component of a social interaction.

The FDA... may end up approving MDMA for certain uses ... If it gets approved, my personal feeling is that it'll have some addictive liability.