ical to the reward process. Drugs such as amphetamine and cocaine that enhance the release of dopamine also augment the rate of self -stimulation. Drugs that block dopamine release or its ability to bind to its receptor decrease the rate of self-stimulation.
The reward system may therefore play a role in the process of addiction to certain abused drugs.
At a purely chemical level, every experience humans find enjoyable- whether listening to music, embracing a lover or sayoring chocolate- amounts to little more than an explosion of dopamine in the nucleus accumbens, as exhilarating and ephemeral as a firecracker.
Too little dopamine in certain areas of the brain triggers the tremors and paralysis of Parkinson¡¯s disease. Too much causes the hallucinations and bizarre thoughts of schizophrenia.
Dopamine, however, is more than just a feel-good molecule. It also exercises extraordinary power over learning and memory.Indeed, the brain has many devious tricks for ensuring that the irrational act of taking drugs, deemed ¡°good¡± because it enhances dopamine, will be repeated.
The addicts¡¯ neurons, assaulted by abnormally high levels of dopamine, have responded defensively and reduced the number of sites (or receptors) to which dopamine can bind.
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