A chemical that is released by neurons (nerve cells) in the brain. Neurotransmitters work as chemical messengers; they transmit information from one neuron to another. Neurotransmitters may either stimulate or inhibit activity in the receiving neuron.
Examples of neurotransmitters include serotonin, dopamine, GABA, and norepinephrine.
Source: Friedel RO. Dopamine Dysfunction in Borderline Personality Disorder: A Hypothesis. Neuropsychopharmacology. 29:1029-1039, 2004.

