Brain Health Article

The cerebellum

The cerebellum is located below the cerebrum and behind the brain stem. It is butterfly-shaped, with the "wings" known as the cerebellar hemispheres. The cerebellum controls many subconscious activities, such as balance and muscular coordination. Disorders related to damage of the cerebellum are ataxia (problems with coordination), dysarthria (unclear speech resulting from problems controlling the muscles used in speaking), and nystagmus (uncontrollable jerking of the eyeballs). A brain tumor that is relatively common in children known as medullablastoma grows in the cerebellum.

Studying the brain

Researchers have discovered that neurons carry information through the nervous system in the form of brief electrical impulses called action potentials. When an impulse reaches the end of an axon, neurotransmitters are released at junctions called synapses. The neurotransmitters are chemicals that bind to receptors on the receiving neurons, triggering the continuation of the impulse. Fifty different neurotransmitters have been discovered since the first one was identified in 1920. By studying the chemical effects of neurotransmitters in the brain, scientists are developing treatments for mental disorders and are learning more about how drugs affect the brain.

Scientists once believed that brain cells do not regenerate, thereby making brain injuries and brain diseases untreatable. Since the late 1990s, researchers have been testing treatment for such patients with neuron transplants, introducing nerve tissue into the brain. They have also been studying substances, such as nerve growth factor (NGF), that someday could be used to help regrow nerve tissue.

Technology provides useful tools for researching the brain and helping patients with brain disorders. An electroencephalogram (EEG) is a record of brain waves, electrical activity generated in the brain. An EEG is obtained by positioning electrodes on the head and amplifying the waves with an electroencephalograph and is valuable in diagnosing brain diseases such as epilepsy and tumors.

Scientists use three other techniques to study and understand the brain and diagnose disorders:

(1) Magnetic resonance imaging (MRI) uses a magnetic field to display the living brain at various depths as if in slices. (2) Positron emission tomography (PET) results in color images of the brain displayed on the screen of a monitor. During this test, a technician injects a small amount of a substance, such as glucose, that is marked with a radioactive tag. The marked substance shows where glucose is consumed in the brain. PET is used to study the chemistry and activity of the normal brain and to diagnose abnormalities such as tumors.

(3) Magnetoencephalography (MEG) measures the electromagnetic fields created between neurons as electrochemical information is passed along. When under the machine, if the subject is told, "wiggle your toes," the readout is an instant picture of the brain at work. Concentric colored rings appear on the computer screen that pinpoint the brain signals even before the toes are actually wiggled.

Using an MRI along with MEG, physicians and scientists can look into the brain without using surgery. They foresee that these techniques could help paralysis victims move by supplying information on how to stimulate their muscles or indicating the signals needed to control an artificial limb.

Books

Bear, Mark F., Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. Baltimore: Williams &Wilkins, 1996.

Burstein, John. The Mind by Slim Goodbody. Minneapolis, MN: Fairview Press, 1996.

Carey, Joseph, ed. Brain Facts. Washington, D.C.: Society for Neuroscience, 1993.

Greenfield, Susan A. ed. The Human Mind Explained: An Owner's Guide to the Mysteries of the Mind. New York: Henry Holt, 1996.

Howard, Pierce J. The Owner's Manual for the Brain: Everyday Applications from Mind-Brain Research. Austin, TX: Leornian Press, 1994.

Jackson, Carolyn, ed. How Things Work: The Brain. Alexandria, VA: Time-Life Books, 1990.

Audiovisual recordings

The Mind. Alexandria, VA: PBS Video, 1988. (Series of nine 1-hour videocassettes.)

The Nature of the Nerve Impulse. Films for the Humanities and Sciences, 1994-95. (Videocassette.)