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On The Brain

Extracts from an article by Marian Diamond

The 1990s 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.

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.


Increases in cortical growth as a consequence of stimulating environmental input have been demonstrated at every age, including very old age. 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.


About the author: Marian Diamond is a professor of neuroscience and anatomy at Berkeley and a pioneer in research on brain enrichment.