For thousands of years humans have been aware that certain chemical substances can change people’s behavior
by influencing their muscular coordination, their perceptions, their mood, or even their thoughts.
We now call these mind-altering substances psychoactive drugs.
Some cultures used drugs during religious rituals;
other cultures used them to control pain or boost energy during war.
But as more people became aware of these substances, a familiar pattern emerged:
People began using these drugs simply to induce a pleasurable experience.
Archeologists tell us that the recreational use of alcohol in the form of beer dates back at least 10,000 years!
To help us understand how psychoactive drugs impacts us the way we do,
we need to look at the basic principles of drug action on the brain.