The reward system is an important part of the brain, but it
often receives scant attention in medical school. This
neurological system is activated when we feel pleasure and it
motivates us to work for and to seek out food, sex, water and
other rewards. It developed early in evolution and is present in
modern humans, essentially unchanged from our early ancestors.
Unfortunately, certain plant products such as opioids or cocaine
are, by coincidence, able to fit perfectly into receptors in the
reward circuits where they can directly produce a sensation of
reward or euphoria. Normally a sense of pleasure is earned
through constructive behaviors and natural drives. But even a
tiny amount of cocaine can directly activate this same pleasure
system without the need for the usual work. Cocaine’s chemical
structure blocks the normal mechanism of the neurotransmitter
dopamine, with the result that, instead of the nerve cell
releasing dopamine and taking it back up again after its signal
is sent, cocaine blocks the reup