Dopamine is a neurotransmitter that is found throughout the human body. It acts as a chemical messenger to affect movement, emotions and the ability to experience both pleasure and pain. Additionally, dopamine plays a large role in addiction.
Dopamine also has many medical effects. The neurotransmitter is found in greatest concentration in the substania nigra in the brain. It is here that many neurons containing dopamine are clustered together to help the brain process many types of stimuli. However, if the dopamine neurons in the substania nigra begin to die, a person may develop Parkinson's disease due to a lack of dopamine in the bloodstream.