Answer:
Drugs affect the way signals are sent in the brain’s reward
circuit, which is a network of structures that is activated
when you do something pleasurable.
Dopamine is a chemical that helps signals pass between
nerve cells in the brain. When you do something enjoyable,
such as eating chocolate, dopamine levels increase in
the brain (see top diagram). Receptors detect the rise in
dopamine, which helps your brain remember the pleasurable
behavior so that you are more likely to want to do it again.
Using drugs, including opioids, causes a rise in
dopamine levels that is far greater than the increase from
other enjoyable activities (see bottom diagram). When
drugs are misused over time, the brain becomes used to the
extreme surge of dopamine that drugs deliver. This leads
to powerful cravings that make it very difficult to stop. The
state of being ruled by these cravings is addiction.
Explanation:
