Introduction
Addiction is a disorder of the brain's reward and learning systems. At its core, it involves the hijacking of neural circuits that evolved to motivate survival behaviors -- eating, social bonding, reproduction -- by substances or activities that produce supranormal dopamine signals. Understanding the pharmacology of addiction means understanding how drugs change the brain at the molecular, cellular, and circuit levels, and why these changes are so resistant to reversal. This understanding also reveals why psychedelics and other novel compounds may offer fundamentally different therapeutic approaches.
