Build a Better Brain

Learning, the process by which we acquire information about our world, may actually change our brains for the better.

By Beth Livermore, published on September 01, 1992 - last reviewed on October 02, 2009

Sometime near the high-school prom age—around 18 years old—networks stop forming. We are hard-wired by the end of adolescence. Each of us is left with a "brainprint," or network system, which like a fingerprint, is unique to each one of us. This is the hardware that processes our thoughts.

Once it's in place, certain opportunities are no longer available to us. If, for example, we learn a second language after adolescence, it comes out sounding something like the first one. "We are incapable of acquiring new languages without an accent after adolescence," reports Mark Konishi, a biologist at California Institute of Technology who studies bird-song development. During development the connections form that process sound. But once our brains are so shaped, Konishi says, "we probably use the same neural substrate to process new sounds."

However, the brain is an enormously adaptive organ: The connections between neurons proliferate and shrink depending upon use. The links between them can be strengthened or weakened. "Brain networks can always be fine-tuned," says neurobiologist Stevens, of the Howard Hughes Medical Institute at Salk Institute in La Jolla. The more synapses between cells, the more avenues for information transmission. The better your cells communicate with one another, the more information you can likely digest, understand and recall efficiently.

"Smarter" people—those who can consume and regurgitate facts with the efficiency of machines—may in fact have a greater number of neural networks more intricately woven together. And recall of any one part seems to summon up a whole web of information.

Pictures of the brain in action confirm this model of efficiency of information flow. Researchers scanning human brains by positron emission tomography (PET)—which highlights the regions that work hardest during various tasks—found that "smarter" brains consume less energy than other brains; to do the same tasks they require less glucose, their favored fuel. "It maybe that once the brain becomes really well grooved you don't need as much energy," explains Eric Kandel, M.D., a neurobiologist at the Howard Hughes Medical Institute at Columbia University in New York.

Perhaps that explains why rats raised in enriched environments later learn faster than counterparts kept in barren cages. And perhaps it will help researchers to understand a recent controversial study showing a significant correlation between low levels of education and the incidence of Alzheimer's disease. According to neuroscientist Robert Katzman, Ph.D., of the University of California at San Diego, individuals who lack formal education may develop fewer synapses, or junctures between neurons, than individuals who have routinely stretched their minds. Then, when disease occurs, there is less brain reserve to call on, he says. When Alzheimer's disease strikes them, the loss of synapses is dramatic and quick to show.

Katzman hopes to directly investigate whether the number of synapses in uneducated people is actually different from that of educated people. In the meantime, neurobiologist Richard Mayeux, Ph.D., of Columbia University, appears to have confirmed part of what Katzman is getting at. He has shown that people with high IQs can withstand more brain scarring than less gifted people before they show a noticeable loss of intellect.

So managing large amounts of information throughout your life—as well as keeping your mind active into old age—doesn't just make you smarter, it also appears to buy you some time should you be stricken with a degenerative brain disease. And it can also help you withstand the more everyday ravages of age.

What makes it possible to change our brains to work faster and smarter? Human studies show that there are two kinds of learning. Declarative—or factual-learning consists of the acquisition of details about people, places, and things; it is presumed to be highly associative, drawing on rich neural interconnections. Procedural learning, on the other hand, involves information on how to do things that utilize motor skills and perceptual strategies, such as driving a car.

Each relies on different neural systems in the brain. Procedural learning, more narrow-channel, involves the specific sensory and motor systems underlying the particular skill. Declarative learning is processed in the hippocampus—a small, seahorse-shaped structure located at the base of the temporal lobe of the cerebral cortex. Not only is the hippocampus central to the formation and retrieval of lasting memories, it is part of the limbic system, or emotional brain.

The details of the still-unfolding story of the hippocampus and its role in the flow of information started with amnesiacs and are spun increasingly from nonhuman sources. Sophisticated as the new imaging technology is, it does not go far enough to pin down the complex doings of the human brain at work. For this, scientists have turned to the simpler systems of the sea snail Aplysia, and to rats and cats, among other creatures.

The bet is that the basic cellular processes in these neurons are similar to ours; that the same kinds of changes that animate the brains of "lower" animals animate ours as well. Even as this article goes to press, the various models are producing vast amounts of information that provide an increasingly complete idea of how brains input the newspaper stories, the lectures, the exhibits, the news, and the noise we want to remember.

At the start of this chain, the sensory organs—eyes, ears, nose, mouth, fingertips—transform stimuli into rhythmic patterns of electrical impulses. Then, one by one, millions of neurons pass the charge on to their neighbors. This process is accomplished by chemical as well as electrical means.