4. The ABCs of Drug Action in the Brain

The patient told his counselor that he had fallen into addiction by taking more and more drugs over several months. “I used to be able to stop, but now, if I don’t have the stuff, I go crazy. They say it’s in my head, my brain. Somehow it’s changed...” The patient is right. The brain is changed, and to understand that, we need to know how the brain works at the basic level.

The Nerve Cell

Our brain directs our body and its behavior by using its basic functional unit, the nerve cell. The nerve cell, or neuron, has a cell body with branching arms called dendrites, a longer thread-like part known as an axon, and nerve terminals that are found at the ends of the axon (see Figure 4-1, left). The nerve terminal ...

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