Parkinson’s disease is a chronic progressive neurological disease that affects nerve cells (neurons) in an area of the brain near the neck, known as the substantia nigra. These cells normally produce dopamine, a chemical (neurotransmitter) that transmits signals between areas in the brain. These signals, when working normally, coordinate smooth and balanced muscle movement. Parkinson’s disease, however, causes neurons in the substantia nigra cells to die, leading to a lack of dopamine in the brain, especially in the part of the brain known as the basal ganglia. The basal ganglia are responsible for organizing movement commands from other parts of the brain. The loss of dopamine causes patients to lose the ability to control their body movements.