Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School (7 page)

some assembly required

How does this fantastic biology work? Infants provide a front-row seat to one of the most remarkable construction projects on Earth. Every newly born brain should come with a sticker saying “some assembly required.” The human brain, only partially constructed at birth, won’t be fully assembled for years to come. The biggest construction programs aren’t finished until you are in your early 20s, with fine-tuning well into your mid-40s.

When babies are born, their brains have about the same number of connections as adults have. That doesn’t last long. By the time children are 3 years old, the connections in specific regions of their brains have doubled or even tripled. (This has given rise to the popular belief that infant brain development is
the
critical key to intellectual success in life. That’s not true, but that’s another story.) This doubling and tripling doesn’t last long, either. The brain soon takes thousands of tiny pruning shears and trims back a lot of this hard work. By the time children are 8 or so, they’re back to their adult numbers. And if kids never went through puberty, that would be the end of the story. In fact, it is only the middle of the story.

At puberty, the whole thing starts over again. Quite different regions in the brain begin developing. Once again, you see frenetic neural outgrowth and furious pruning back. It isn’t until parents begin thinking about college financial aid for their high schoolers that their brains begin to settle down to their adult forms (sort of). It’s like a double-humped camel. From a connectivity point of view, there is a great deal of activity in the terrible twos and then, during the terrible teens, a great deal more.

Though that might seem like cellular soldiers obeying growth commands in lockstep formation, nothing approaching military precision is observed in the messy world of brain development. And it is at this imprecise point that brain development meets Brain Rule. Even a cursory inspection of the data reveals remarkable variation in growth patterns from one person to the next. Whether examining toddlers or teenagers, different regions in different children develop at different rates. There is a remarkable degree of diversity in the specific areas that grow and prune, and with what enthusiasm they do so.

I’m reminded of this whenever I see the class pictures that captured my wife’s journey through the American elementary-school system. My wife went to school with virtually the same people for her entire K–12 experience (and actually remained friends with most of them). Though the teachers’ dated hairstyles are the subject of much laughter for us, I often focus on what the kids looked like back then. I always shake my head in disbelief.

In the first picture, the kids are all in grade one. They’re about the same age, but they don’t look it. Some kids are short. Some are tall. Some look like mature little athletes. Some look as if they just got out of diapers. The girls almost always appear older than the boys. It’s even worse in the junior-high pictures of this same class. Some of the boys look as if they haven’t developed much since third grade. Others are clearly beginning to sprout whiskers. Some of the girls, flat chested and uncurved, look a lot like boys. Some seem developed enough to make babies.

Why do I bring this up? If we had X-ray eyes capable of penetrating their little skulls, we would find that the brains of these kids are
just as unevenly developed
as their bodies.

the jennifer aniston neuron

We are born into this world carrying a number of preset circuits. These control basic housekeeping functions like breathing, heartbeat, your ability to know where your foot is even if you can’t see it, and so on. Researchers call this “experience independent” wiring. The brain also leaves parts of its neural construction project unfinished at birth, waiting for external experience to direct it. This “experience expectant” wiring is related to areas such as visual acuity and perhaps language acquisition. And, finally, we have “experience dependent” wiring. It may best be explained with a story about Jennifer Aniston. You might want to skip the next paragraph if you are squeamish.

Ready? A man is lying in surgery with his brain partially exposed to the air. He is conscious. The reason he is not crying out in agony is that the brain has no pain neurons. He can’t feel the needle-sharp electrodes piercing his nerve cells. The man is about to have some of his neural tissue removed—resected, in surgical parlance—because of intractable, life-threatening epilepsy. Suddenly, one of the surgeons whips out a photo of Jennifer Aniston and shows it to the patient. A neuron in the man’s head fires excitedly. The surgeon lets out a war whoop.

Sound like a grade B movie? This experiment really happened. The neuron in question responded to seven photographs of actress Jennifer Aniston, while it practically ignored the 80 other images of everything else, including famous and non-famous people. Lead scientist Quian Quiroga said, “The first time we saw a neuron firing to seven different pictures of Jennifer Aniston—and nothing else—we literally jumped out of our chairs.” There is a neuron lurking in your head that is stimulated only when Jennifer Aniston is in the room.

A Jennifer Aniston
neuron
? How could this be? Surely there is nothing in our evolutionary history suggesting that Jennifer Aniston is a permanent denizen of our brain wiring. (Aniston wasn’t even born until 1969, and there are regions in our brain whose designs are millions of years old). To make matters worse, the researchers also found a Halle Berry-specific neuron, a cell in the man’s brain that wouldn’t respond to pictures of Aniston or anything else. Just Berry. He also had a neuron specific to Bill Clinton. It no doubt was helpful to have a sense of humor while doing this kind of brain research.

Welcome to the world of experience-dependent brain wiring, where a great deal of the brain is hard-wired
not
to be hard-wired. Like a beautiful, rigorously trained ballerina, we are hard-wired to be flexible.

We can immediately divide the world’s brains into those who know of Jennifer Aniston or Halle Berry and those who don’t. The brains of those who do are not wired the same way as those who don’t. This seemingly ridiculous observation underlies a much larger concept. Our brains are so sensitive to external inputs that their physical wiring depends upon the culture in which they find themselves.

Even identical twins do not have identical brain wiring. Consider this thought experiment: Suppose two adult male twins rent the Halle Berry movie
Catwoman
, and we in our nifty little submarine are viewing their brains while they watch. Even though they are in the same room, sitting on the same couch, the twins see the movie from slightly different angles. We find that their brains are encoding visual memories of the video differently, in part because it is impossible to observe the video from the same spot. Seconds into the movie, they are already wiring themselves differently.

One of the twins earlier in the day read a magazine story about panned action movies, a picture of Berry figuring prominently on the cover. While watching the video, this twin’s brain is simultaneously accessing memories of the magazine. We observe that his brain is busy comparing and contrasting comments from the text with the movie and is assessing whether he agrees with them. The other twin has not seen this magazine, so his brain isn’t doing this. Even though the difference may seem subtle, the two brains are creating different memories of the same movie.

That’s the power of the Brain Rule. Learning results in physical changes in the brain, and these changes are unique to each individual. Not even identical twins having identical experiences possess brains that wire themselves exactly the same way. And you can trace the whole thing to experience.

on the street where you live

Perhaps a question is now popping up in your brain: If every brain is wired differently from every other brain, can we know
anything
about the organ?

Well, yes. The brain has billions of cells whose collective electrical efforts make a loving, wonderful you or, perhaps with less complexity, Kandel’s sea slug. All of these nerves work in a similar fashion. Every human comes equipped with a hippocampus, a pituitary gland, and the most sophisticated thinking store of electrochemistry on the planet: a cortex. These tissues function the same way in every brain.

How then can we explain the individuality? Consider a highway. The United States has one of the most extensive and complex ground transportation systems in the world. There are lots of variations on the idea of “road,” from interstate freeways, turnpikes, and state highways to residential streets, one-lane alleys, and dirt roads. Pathways in the human brain are similarly diverse. We have the neural equivalents of large interstate freeways, turnpikes, and state highways. These big trunks are the same from one person to the next, functioning in yours about the same way they function in mine. So a great deal of the structure and function of the brain is predictable, a property that allows the word “science” to be attached to the end of the word “neuro” and keeps people like me employed. Such similarity may be the ultimate fruit of the double-humped developmental program we talked of previously. That’s the experience-independent wiring.

It’s when you get to the smaller routes—the brain’s equivalent of residential streets, one-laners and dirt roads—that individual patterns begin to show up. Every brain has a lot of these smaller paths, and in no two people are they identical. The individuality is seen at the level of the very small, but because we have so much of it, the very small amounts to a big deal.

It is one thing to demonstrate that every brain is wired differently from every other brain. It is another to say that this affects intelligence. Two scientists, a behavioral theorist and a neurosurgeon, offer differing perspectives on the subject. The theorist believes in seven to nine categories of multiple intelligence. The neurosurgeon also believes in multiple categories. He thinks there may be billions.

Meet Howard Gardner, psychologist, author, educator, and father of the so-called Multiple Intelligences movement. Gardner had the audacity to suggest that the competency of the human mind is too multifaceted to be boiled down to simplistic numerical measures. He threw out the idea of IQ tests, and then he attempted to reframe the question of human intellectual skill. Like a cognitive Jane Goodall in an urban jungle, Gardner and his colleagues observed real people in the act of learning—at school, at work, at play, at
life
. He began to notice categories of intellectual talent that people used every day that were not always identified as being “intelligent” and certainly were not measurable by IQ tests. After thinking about things for a long time, he published his findings in a book called
Frames of Mind: The Theory of Multiple Intelligences
. It set off a firestorm of debate that burns unabated to this day.

Gardner believes he has observed at least seven categories of intelligence: verbal/linguistic, musical/ rhythmic, logical/mathemati-cal, spatial, bodily/ kinesthetic, interpersonal, and intrapersonal. He calls these “entry points” into the inner workings of the human mind. The categories don’t always intersect with one another, and Gardner has said, “If I know you’re very good in music, I can predict with just about zero accuracy whether you’re going to be good or bad in other things.”

Some researchers think Gardner is resting on his opinion, not on his data. But none of his critics attack the underlying thesis that the human intellect is multifaceted. To date, Gardner’s efforts represent the first serious attempt to provide an alternative to numerical descriptions of human cognition.

mapping the brain

But categories of intelligence may number more than 7 billion—roughly the population of the world. You can get a sense of this by watching skilled neurosurgeon George Ojemann examine the exposed brain of a 4-year-old girl. Ojemann has a shock of white hair, piercing eyes, and the quiet authority of someone who for decades has watched people live and die in the operating room. He is one of the great neurosurgeons of our time, and he is an expert at a technique called electrical stimulation mapping.

He is hovering over a girl with severe epilepsy. She is fully conscious, her brain exposed to the air. He is there to remove some of her misbehaving brain cells. Before Ojemann takes out anything, however, he has to make a map. He wields a slender white wand attached to a wire, a cortical stimulator, which sends out small, unobtrusive electrical shocks to anything it touches. If it brushed against your hand, you would feel only a slight tingly sensation.

Ojemann gently touches one end of the wand to an area of the little girl’s brain and then asks her, “Did you feel anything?” She says dreamily, “Somebody just touched my hand.” He puts a tiny piece of paper on the area. He touches another spot. She exclaims, “Somebody just touched my cheek!” Another tiny piece of paper. This call and response goes on for hours. Like a neural cartographer, Ojemann is mapping the various functions of his little patient’s brain, with special attention paid to the areas close to her epileptic tissue.

These are tests of the little girl’s motor skills. For reasons not well understood, however, epileptic tissues are often disturbingly adjacent to critical language areas. So Ojemann also pays close attention to the regions involved in language processing, where words and sentences and grammatical concepts are stored. This child happens to be bilingual, so language areas essential for both Spanish and English will need to be mapped. A paper dot marked “S” is applied to the regions where Spanish exists, and a small “E” where English is stored. Ojemann does this painstaking work with every single patient who undergoes this type of surgery. Why? The answer is a stunner. He has to map each individual’s critical function areas because
he doesn’t know where they are.

Ojemann can’t predict the function of very precise areas in advance of the surgery because no two brains are wired identically. Not in terms of structure. Not in terms of function. For example, from nouns to verbs to aspects of grammar, we each store language in different areas, recruiting different regions for different components. Bilingual people don’t even store their Spanish and their English in similar places.