| Different types of cells secrete different neurotransmitters. Each brain chemical works in widely spread but fairly specific brain locations and may have a different effect according to where it is activated. All of the major neurotransmitters are made from amino acids except acetycholine. Some 60 neurotransmitters have been identified, but the most important, listed top to bottom, seem to be: |
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Dopamine
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Controls arousal levels in many parts of the brain and is vital for giving physical motivation. When levels are severely depleted, as in Parkinson's disease, people may find it impossible to move forward voluntarily. Low dopamine may also be implicated in mental stasis. LSD and other hallucinogenic drugs are thought to work on the dopamine system. |
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Serotonin
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This is the neurotransmitter enhanced by Prozac, and has thus become known as the 'feel-good' chemical. It has a profound effect on mood and anxiety -- high levels of it, or sensitivity to it, are associated with serenity and optimism. |
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Acetylcholine (ACh)
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Controls activity in brain areas connected with attention, learning and memory. People with Alzheimer's disease typically have low levels of ACh in the cerebral cortex, and drugs that boost its action may improve memory in such patients. |
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Noradrenaline
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Mainly an excitatory chemical that induces physical and mental arousal and elevated mood. Production is centered in an area of the brain called the locus coreuleus, which is one of several putative candidates for the brain's 'pleasure' centre. |
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Glutamate
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The brain's major excitatory neurotransmitter, vital for forging the links between neurons that are the basis of learning and long-term memory. |
| Enkephalins and Endorphins |
These are opioids that, like the drugs heroine and morphine, modulate pain, reduce stress and promote a sensation of floaty, oceanic calm. They also depress physical functions like breathing and may produce physical dependence. |
Excerpts from
"Mapping the Mind", Rita Carter
Weidenfeld & Nicolson, 1998
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