Parkinson's disease, neurons and dopamine. Illustration of the difference in dopamine levels at a synapse between neurons in a healthy person (left) and a patient with Parkinson's disease (right). Dopamine (pale blue spheres) is a neurotransmitter that is released as part of the process of transmitting nerve impulses between nerve cells across gaps called synapses. The dopamine attaches to receptors (pink) on the nerve cells on the other side of the synaptic gap. Levels of dopamine are reduced (shown at left) in specific brain areas in cases of Parkinson's disease. This results in tremors and movement disorders. Dopamine replacement therapy (DRT) can be used to treat the symptoms. For this artwork without labels, see C030/3215.