The Molecule of More

THE MOLECULE OF MORE

are  perfectly logical. If someone offered you  a  choice between a  meal 
at a nice restaurant, even the nicest restaurant in town, and a check
for million dollars, it’s ridiculous to think you’d choose dinner. That’s
exactly how an addict feels when choosing between, say, paying the
rent and buying crack. He chooses the one that will lead to the bigger
dopamine hit. The euphoria of crack cocaine is bigger than just about
any experience you can name. That’s rational from the point of view of
desire dopamine, which is what drives the behavior of addicts.
Drugs are  fundamentally different from natural dopamine triggers. 
When we’re starving, there’s nothing more motivating than getting
food. But after we eat, the motivation for getting food declines because
satiety circuits become active and shut down the desire circuit. There
are checks and balances in place to keep everything stable. But there’s
no satiety circuit for crack. Addicts take drugs until they pass out, get
sick, or run out of money. If you ask an addict how much crack he
wants, there is only one answer: more.
Let’s look at it from another angle. The goal of the dopamine sys-
tem is to predict the future and, when an unexpected reward occurs, to
send a signal that says, “Pay attention. It’s time to learn something new
about the world.” In this way, circuits bathed in dopamine become mal-
leable. They morph into new patterns. New memories are laid down,
new connections are established. “Remember what happened,” says
the dopamine circuit. “This may be useful in the future.”
What’s the end result? You don’t get surprised the next time the
reward occurs. When you discovered the website that streamed your
favorite music, it was exciting. But the next time you visited the site it
wasn’t. There’s no longer any reward prediction error. Dopamine is not
meant to be an enduring reservoir of joy. By shaping the brain to make
surprising events predictable, dopamine maximizes resources, as  it  is 
supposed to do, but in the process, by eliminating surprise and extin-
guishing reward-prediction error, it suppresses its own activity.
But addictive drugs are so powerful that they bypass the compli-
cated circuitry of  surprise and  prediction and  artificially ignite the 
dopamine system. In this way, they scramble everything up. All that’s
left is a gnawing craving for more.