Inner Space: The Brain

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Traveling to the moon may have been much easier than exploring the space inside our heads.

Astronomers send signals across billions of miles of space, changing the course of a space probe so it will fly by Neptune. Physicists smash nearly invisible particles in order to peek back at matter and energy as they existed when the universe was a few trillionths of a second old.

When you read about such spectacular feats, you may get the impression that scientists are well on their way to figuring out everything there is to know about the world. But if you listen to scientists, you hear a very different story. For scientists, the world is still full of mystery. In fact, what we don't know about the world is much greater than what we do know.

For example, how does the brain work? No scientific puzzle has been more difficult to solve. You might think brains would be easy to study — after all, they're not far away, like Neptune, or incredibly small, like the particles physicists study. But the closer scientists look, the more they see that ordinary brains are among the most puzzling objects in the universe.

To begin with, brains are surprisingly complex — much more complex, and much more powerful, than the most advanced computers. Remember the exercises in your kindergarten workbooks? What's wrong with this picture? Which snowman is different? Which object doesn't belong? The smartest computers in the world can't do these as well as you could when you were 5.

Scientists have been studying brains seriously for about 70 years — but not necessarily human brains. They've used microelectrodes to measure electrical activity in the brain cells of animals such as squid, snails, insects, and rodents. They've gathered enough information about brain cells to fill several encyclopedias. But they still don't know why brains are so good at getting and using information.

"Neurobiologists" (scientists who study brains) have learned a lot about the complicated cells that make up brains — they're called "neurons." The human brain is made of some 10 trillion neurons; each neuron branches out to communicate with as many as 150,000 other neurons; neurons pass along information in the form of small electrical charges — these things we know.

Animal brains, including ours, are composed of networks of fantastically complex cells called " neurons " (also known as nerve cells). Each neuron has an axon, a fiber that sends messages to other neurons. Individual neurons can't think, but networks of neurons can.

But how does your brain turn electrical signals into vision. Where do you "see" the images that enter your eyes? Which parts of your brain do algebra? Which parts allow you to play the guitar, tap your foot, and sing, all at the same time? How do we form beliefs, ideas, decisions?

A lot of people would like to know, including medical researchers who want to solve health problems; people in business and industry who want to better computers and robots; and military planners who want smarter weapons.

In 1997, the U.S. Department of Defense announced it would spend millions of dollars on brain research in the next decade. One spokesperson said he hoped that within five years scientists would be able to build a missile that could find its way around as well as a bumblebee.

"No way," says James Bower, a leading neurobiologist. Not in our lifetime.

In the summer of 1997, President Bush declared the 1990s The Decade of the Brain — a pledge that calls to mind President Kennedy's vow to put an American on the moon by the end of the 1960s. But traveling to the moon may have been much easier than exploring the space inside our heads. Certainly most neurobiologists expect to be scratching their heads over brains long after the end of the 1990s.