The Brain . . . Use It or Lose It
Marian Cleeves Diamond

The l990s have been declared the Decade of the Brain and the Decade of Education. The human brain receives all education and is the source of all behavior. It is the most complex mass of protoplasm on Earth, and perhaps in our galaxy. A simple essay can only begin to describe its magnificence on the one hand and its malice on the other. By offering a few facts about the development of the brain, I hope to emphasize its role in providing the substrate for education before and after birth.

Various parts of the brain develop at various rates. The part constituting the outer layers of the cerebral hemispheres, called the cerebral cortex (cortex means "bark"), deals with higher cognitive processing. The cerebral cortex is a likely target for a study of the effects of education on the brain. The cortex ranges from 1.5 to 4.5 millimeters thick, with nerve cells accounting for most of the thickness. How do these cells respond to their external environment or, in more specific terms, to education?

The most recently evolved part of the cerebral cortex. the neocortex, has its full complement of nerve cells at a person's birth. Even if an individual lives more than one hundred years, no new nerve cells are formed in this part of the brain. Yet the most rapid growth of the neocortex occurs during the first ten years or so of life.

What, then, is growing? The receptive branches of the nerve cells, called dendrites, are responsible for most of this postnatal neocortical growth, and the neural network they form becomes the "hardware" of intelligence. Dendrites are extensions of the nerve cell membrane that receive the input from other nerve cells. These branches are very responsive to such input, increasing in number with use and decreasing with disuse. The phrase "use it or lose it" definitely applies to this process.

Though most of the research providing information on the plasticity of the brain comes from animal studies, recent experiments from the Brain Research Institute at UCLA have shown similar results in human brains. In Wernicke's area, which deals with word understanding, the nerve cells have more dendrites in college-educated people than in people with only a high school education.

Increases in cortical growth as a consequence of stimulating environmental input have been demonstrated at every age, including very old age. The greatest changes, however-as much as 16 percent increases-have been noted during the period when the cerebral cortex is growing most rapidly --the first ten years. By providing children with challenging experiences through enriched education and environments, those dendrites cannot help but be off to a good start!

Since no two human brains are exactly alike, no one enriched environment will completely satisfy all learners for an extended period. The range of enriched environments for human beings is endless. For some, interacting physically with objects is gratifying; for others, finding and processing information is rewarding; and for still others, working with creative ideas is most enjoyable. But no matter what form enrichment takes, it is the challenge to the nerve cells that is important. Data indicate that passive observation is not enough; one must interact with the environment. One way to be certain of continued enrichment is to stimulate and maintain curiosity throughout a lifetime.

Dr. Marian C. Diamond is professor of anatomy and one of the world's foremost neuroanatomists. She is author of more than 100 scientific articles and three books, including Enriching Heredity (Free Press/Simon and Schuster, 1988). You can reach Marian Diamond at the University of California at Berkeley, Department of Biology, Berkeley, CA 94720.

This article first appeared in Mindshift Connection (vol. 1, no.1), a Zephyr Press publication edited by Dee Dickinson. To subscribe to Mindshift Connection and join the Zephyr network, call (520) 322-5090 or visit the Zephyr website.