| Akinesia | The absence of movement |
| Basal Ganglia | A large group of nuclei deep within the brain that affects movement. The basal ganglia include the caudate nucleus, putamen, globus pallidus, subthalamic nucleus, and substantia nigra. |
| Blood Brain Barrier | A protective barrier that allows only certain substances to enter the brain from blood vessels |
| Bradykinesia | Slowness in performing movements |
| Chorea | Ongoing, rapid, and irregular flitting movements of the body that appear willful, but are involuntary |
| Dopamine Agonist | A drug that binds primarily with dopamine receptors and mimics the action of dopamine |
| Dyskinesia | Abnormal involuntary movements that typically are medication induced |
| Dystonia | Involuntary twisting of the body due to abnormal muscle contractions |
| Enzyme | Proteins that serve as catalysts for biochemical reactions within the brain |
| Essential Tremor | The most common form of tremor, which typically begins in adolescence and young adulthood and becomes more pronounced in middle to advanced years, i.e., after age 50. It comprises a single symptom such as uncontrollable shaking of the head, hands, arms, or other part of the body, which stops when at rest. The condition is often hereditary. |
| Festinating Gait | Involuntary acceleration of one's gait |
| Hypomimia | A mask-like face with little expression |
| Levodopa (L-Dopa) | The chemical precursor to dopamine in the brain; also the most common and most effective agent for managing symptoms of Parkinson's disease. |
| Lewy Bodies | Eosinophilic structures with a dense protein core found in the cytoplasm of pigmented neurons; a pathological marker of Parkinson's disease when found within the substantia nigra. |
| Micrographia | Handwriting that decreases in size |
| Neurotransmitters | Chemicals that transmit nerve impulses across a space (or synapse) from one nerve to another |
| Receptor | A structure on the surface of a cell that selectively binds with substances such as neurotransmitters and hormones |
| Striatum | A mass of grey matter that includes the putamen and caudate |
| Substantia Nigra | Dopamine-producing nerve cells located in the brain stem that control voluntary movement |
| Synapse | The junction between two nerve cells, or neurons |