Dopamine

Dopamine (C8H11NO2)

Dopamine is a neurotransmitter, a chemical that communicates signals from a neuron to a specific cell. As such, It is involved in many neural processes including movement control, emotions, sleep, attention and the experience of pain or pleasure. Although research regarding dopamine and its role in human psychology is not yet extensive, preliminary research and hypotheses suggest that dopamine concentrations effect an individual's personality.

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Sbrools on Wikimedia Commons