Dopamine in Humans

Dopamine is a chemical found in humans---most notably in the brain---discovered by Arvid Carlsson in 1958. It is well known for its effect on high-level cognitive functions, and its excess or deficiency in the body can cause a wide range of illnesses.

Neurotransmitter

• Dopamine is produced from L-DOPA, a precursor chemical, within the brain itself. It acts as a chemical messenger between neurons, particularly those associated with reward and goal-seeking behavior.

Neurohormone

• While dopamine is most well known---and studied---for its role as a neurotransmitter, it is also present outside of the brain. It acts on the sympathetic nervous system as a stimulant during stressful situations and is responsible for humans' fight or flight response.

Rewards and Goal-Seeking Behavior

• Dopamine is the primary neurotransmitter controlling motivation and reward, affecting the pleasure system of the brain.

Drug Abuse

• Dopamine is used in the brain to associate behavior with reward. This natural mechanism can be bypassed with chemicals such as cocaine and amphetamines, such that a powerful "reward" reaction is artificially induced, resulting in compulsion to seek the drug.

Medical Conditions

• Dopamine is implicated in a number of medical conditions. When it is deficient it can cause attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), anhedonia (inability to experience pleasure) and Parkinson's disease. Excess dopamine can cause mania, obsessive compulsive disorder (OCD) and psychosis.