• Neurotransmitter: Neurotransmitter is a chemical substances that allows the brain cells to communicate with each other and send information throughout the body.
• Neurodegenerative disorder: It is a general term used for diseases that cause progressive deterioration of nerve cells, and a corresponding affection of body movements and mental functions. Parkinson's Disease, Alzheimer's disease, Huntington's disease, Motor Neurone Diseases, etc. are included under this category.
• Hallucination: A sensory experience which the patient has but is not actually present. They appear real to the person experiencing it, but are only created by the mind.