The brain is composed of gray and white matter containing millions of nerve cells. These nerve cells, or neurons, communicate through the release of chemicals called neurotransmitters. Once a neuron is stimulated, a neurotransmitter is released from the neuron and it crosses a gap called a synapse; it then binds to a receptor on another neuron, thus passing on a signal.
Parkinson’s disease is a degeneration of the area of the brain responsible for muscle movements, specifically, the pigmented neurons located in the substantia nigra in the midbrain. The destruction of these neurons results in a decreased availability of dopamine, which is a type of neurotransmitter. As a result, nerves in this area cannot send their signal to other nerves in order to direct specific body movements. The result is body tremors, slowness of movement, rigidity and balance problems.