Acetycholine - A neurotransmitter that seems to play a key role in the development of Alzheimer's disease.

Analgesic drugs - Drugs commonly used to relieve pain caused by headaches or muscle aches and pains. Available over the counter, analgesic drugs include aspirin, acetaminophen and ibuprofen.

Aneurysm - A part of an artery wall that has weakened, causing it to balloon outward with blood. Burst aneurysms in the brain are a common cause of stroke.

Anticoagulants - A type of drug that reduces the blood's clotting ability.

Anticonvulsants - A type of drug that helps control seizures, commonly prescribed for people with epilepsy.

Aphasia - A language problem in which the patient has problems understanding speech and writing.

Autonomic nervous system - Controlled by the brainstem, this system is responsible for vital but unconscious functions such as breathing and circulation.

Axon - The major branching fiber of a neuron.

Bradykinesia - Slowness of movement, characteristic of parkinsonism.

Brainstem - The part of the brain responsible for unconscious vital functions, including breathing and circulation.

Carotid endarterectomy - A surgical procedure to remove the plaque inside the carotid artery, performed to treat TIAs.

Cataplexy - A sudden attack of muscle paralysis brought on by an emotional reaction such as anger, fear or joy.

Central nervous system - The brain and spinal cord, the center for the entire nervous system.

Cerebellum - Located at the base of the skull, the cerebellum is the part of the brain responsible for balance and coordination.

Cerebral arteriography - A type of X-ray test used to map blood vessels in the brain, especially useful in determining whether to treat TIAs or stroke with surgery to remove a blockage in a blood vessel. A dye is injected into the bloodstream and a series of X- rays are taken. This test usually requires a 24-hour hospital stay.

Cerebrum - The portion of the brain responsible for conscious functions such as movement, memory and vision.

Cognitive symptoms - symptoms that relate to problems with thought processes, such as memory, judgment, abstract thought and comprehension.

Computerized tomography (CT) - A type of scanning achieved using an ultra-thin X-ray beam that gives doctors clear pictures of the structure of the brain's soft tissues. CT scans are noninvasive, painless and safe.

Congenital - Present since birth.

Continuous positive airway pressure (C-PAP) - A treatment for sleep apnea, the C-PAP is a machine that helps keep the patient's airways open through air pressure. Air is pumped through a face mask that the patient wears while sleeping.

Corpys callosum - The tissue that connects the right and left hemispheres of the cerebrum.

Crypothalamotomy - A surgical treatment for severe Parkinson's disease.

Dementia - loss of mental capabilities, including memory, judgment and intellectual ability, that interferes with daily life.

Dendrite - The smaller branching fibers of a neuron.

Dopamine - a chemical neurotransmitter necessary to move the body smoothly.

Dysarthia - A problem with language in which the patient knows the right words but has problems saying them aloud.

Dysphagia - Problems swallowing food.

Electroencephalography (EEG) - A type of test performed to measure the electrical activity of the brain, often used in diagnosing or managing epilepsy. EEG tests are noninvasive, painless and safe.

Epileptic foci - Also called "hot spots," these are the parts of the brain where a patient's epileptic seizures originate.

Focal - Affecting only one part of the body.

Hemiparesis - Weakness on one side of the body, a common stroke effect.

Hemiplegia - Paralysis on one side of the body, a common effect of stroke.

Hemisphere - A division of the cerebrum. The cerebrum consists of the left and right hemispheres.

Idiopathic - With no known cause.

Infarct - An area of dead tissue.

Ketogenic diet - A special diet that has been shown to help some people with epilepsy, especially children.

Levadopa or L-dopa - a powerful dopamine-replacement drug used to treat Parkinson's.

Magnetic resonance imaging (MRI) - a type of scanning achieved through the use of a magnetic field, particularly useful in taking pictures of soft tissues and nerve fibers. MRI scans are non-invasive, painless and safe.

Medically infractory - Doesn't respond to treatment.

Neuralgia - A medical problem relating to the nerves.

Neuritic plaque - Abnormal cluster of degenerating brain cells, characteristic of Alzheimer's disease.

Neurodegenerative disease - A disease marked by the loss of nerve cells.

Neurofibrillary tangles - Twisted protein fragments inside nerve cells in the brain, characteristic of Alzheimer's disease.

Neuron - A nerve cell.

Neurotransmitter - A specialized chemical messenger produced by nerve cells that helps nerves send messages to each other.

Palsy - paralysis of a group of muscles.

Parkinsonism - a group of diseases with symptoms similar to Parkinson's disease.

Peripheral nervous system - The nerves that run throughout the body, connecting to the central nervous system at the spinal cord.

Positron emission tomography (PET) - PET scans map the brain's blood flow and metabolic activities, giving a clear picture of its biological functioning. PET scans are non-invasive, painless and safe.

Secondary - Due to some other disorder. For example, a secondary dystonia is a symptom of some other disorder.

Seizure - a disturbance of the brain's normal electrical activity, causing a temporary change in behavior, consciousness, bodily movements or sensation. Seizures are the main symptom of epilepsy, but can be caused by a wide variety of conditions.

Side effect - An unwanted effect of drug therapy. Side effects are generally predictable.

Sleep paralysis - The temporary inability to move when dropping off to sleep or after waking up.

Substantia nigra - A part of the brain that produces dopamine.

Synapse - The junction where a signal is transmitted from one nerve cell to another, usually by a neurotransmitter.

Tacrine - A drug that may temporarily improve memory loss in some patients with mild to moderate Alzheimer's.

Thalamus - A part of the brain that controls movement.

Transient ischemic attacks (TIAs) - A risk factor for stroke, TIAs are caused by temporary interruptions to the blood supply of the brain. TIA symptoms are similar to stroke symptoms but disappear within a few minutes.