Take cocaine, for example.4 Normally, when dopamine is released into a synapse, it diffuses across to bind with receptors on the second neuron, changing how likely it is to send a signal. Meanwhile, any excess dopamine in the synapse is sucked back up by the first neuron, where it is recycled. This process is known as reuptake and is controlled by dopamine transporters in the membrane of the first neuron, which you can think of as the vacuum cleaners of the synapse. When someone takes cocaine, the drug enters the brain and blocks the dopamine transporters. This means that when dopamine is
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