Read Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School Online
Authors: John Medina
Tags: #Self-Help
• We took over the Earth by adapting to change itself, after we were forced from the trees to the savannah when climate swings disrupted our food supply.
• Going from four legs to two to walk on the savannah freed up energy to develop a complex brain.
• Symbolic reasoning is a uniquely human talent. It may have arisen from our need to understand one another’s intentions and motivations, allowing us to coordinate within a group.
In 1994, one of the best basketball players in the world—ESPN’s greatest athlete of the 20
th
century—decided to quit the game and take up baseball instead. Jordan failed miserably, hitting .202 in his only full season, the lowest of any regular player in the league that year. He simultaneously committed 11 errors in the outfield, also the league’s worst. Jordan’s performance was so poor, he couldn’t even qualify for a triple-A farm team. Though it seems preposterous that anyone with his physical ability would fail at any athletic activity he put his mind to, the fact that Jordan did not even make the minor leagues is palpable proof that you can.
His failure was that much more embarrassing because another athletic legend, Ken Griffey Jr., was burning up the baseball diamond that same year. Griffey was excelling at all of the skills Jordan seemed to lack—and doing so in the
majors
, thank you. Griffey, then playing for the red-hot Seattle Mariners, maintained this excellence for most of the decade, batting .300 for seven years in the 1990s and at the same time slugging out 422 home runs. He is, at this printing, sixth on the all-time home-runs list.
Like Jordan, Griffey Jr. played in the outfield but, unlike Jordan, he was known for catches so spectacular he seemed to float in the air. Float in the
air?
Wasn’t that the space Jordan was accustomed to inhabiting? But the sacred atmosphere of the baseball park refused to budge for Jordan, and he eventually went back to what his brains and muscles did better than anyone else’s, creating a legendary sequel to a previously stunning basketball career.
What was going on in the bodies of these two athletes? What is it about their brains’ ability to communicate with their muscles and skeletons that made their talents so specialized? It has to do with how their brains were wired. To understand what that means, we will watch what happens in the brain as it is learning, discuss the enormous role of experience in brain development—including how identical twins having an identical experience will not emerge with identical brains—and discover that we each have a Jennifer Aniston neuron. I am not kidding.
fried eggs and blueberries
You have heard since grade school that living things are made of cells, and for the most part, that’s true. There isn’t much that complex biological creatures can do that doesn’t involve cells. You may have little gratitude for this generous contribution to your existence, but your cells make up for the indifference by ensuring that you can’t control them. For the most part, they purr and hum behind the scenes, content to supervise virtually everything you will ever experience, much of which lies outside your awareness. Some cells are so unassuming, they find their normal function only after they can’t function. The surface of your skin, for example—all 9 pounds of it—literally is deceased. This allows the rest of your cells to support your daily life free of wind, rain, and spilled nacho cheese at a basketball game. It is accurate to say that nearly every inch of your outer physical presentation to the world is dead.
The biological structures of the cells that are alive are fairly easy to understand. Most look just like fried eggs. The white of the egg we call the cytoplasm; the center yolk is the nucleus. The nucleus contains that master blueprint molecule and newly christened patron saint of wrongfully convicted criminals: DNA. DNA possesses genes, small snippets of biological instructions, that guide everything from how tall you become to how you respond to stress. A lot of genetic material fits inside that yolk-like nucleus. Nearly 6 feet of the stuff are crammed into a space that is measured in microns. A micron is 1/25,000
th
of an inch, which means putting DNA into your nucleus is like taking 30 miles of fishing line and stuffing it into a blueberry. The nucleus is a crowded place.
One of the most unexpected findings of recent years is that this DNA, or deoxyribonucleic acid, is not randomly jammed into the nucleus, as one might stuff cotton into a teddy bear. Rather, DNA is folded into the nucleus in a complex and tightly regulated manner. The reason for this molecular origami: cellular career options. Fold the DNA one way and the cell will become a contributing member of your liver. Fold it another way and the cell will become part of your busy bloodstream. Fold it a third way and you get a nerve cell—and the ability to read this sentence.
So what does one of those nerve cells look like? Take that fried egg and smash it with your foot, splattering it across the floor. The resulting mess may look like a many-pointed star. Now take one tip of that star and stretch it out. Way out. Using your thumb, now squish the farthest region of the point you just stretched. This creates a smaller version of that multipronged shape. Two smashed stars separated by a long, thin line. There’s your typical nerve. Nerve cells come in many sizes and shapes, but most have this basic framework. The foot-stomped fried-egg splatter is called the nerve’s cell body. The many points on the resulting star are called dendrites. The region you stretched out is called an axon, and the smaller, thumb-induced starburst at the farther end of the axon is called the axon terminal.
These cells help to mediate something as sophisticated as human thought. To understand how, we must journey into the Lilliputian world of the neuron, and to do that, I would like to borrow from a movie I saw as a child. It was called
Fantastic Voyage
, written by Harry Kleiner and popularized afterward in a book by legendary science-fiction writer Isaac Asimov. Using a premise best described as
Honey, I Shrunk the Submarine
, the film follows a group of researchers exploring the internal workings of the human body—in a submersible reduced to microscopic size. We are going to enter such a submarine, which will allow us to roam around the insides of a typical nerve cell and the watery world in which it is anchored. Our initial port of call is to a neuron that resides in the hippocampus.
When we arrive at this hippocampal neuron, it looks as if we’ve landed in an ancient, underwater forest. Somehow it has become electrified, which means we are going to have to be careful. Everywhere there are submerged jumbles of branches, limbs, and large, trunk-like objects. And everywhere sparks of electric current run up and down those trunks. Occasionally, large clouds of tiny chemicals erupt from one end of the tree trunks, after the electricity has convulsed through them.
These are not trees. These are neurons, with some odd structural distinctions. Hovering close to one of them, for example, we realize that the “bark” feels surprisingly like grease. That’s because it
is
grease. In the balmy interior of the human body, the exterior of the neuron, the phospholipid bilayer, is the consistency of Mazola oil. It’s the interior structures that give a neuron its shape, much as the human skeleton gives the body its shape. When we plunge into the interior of the cell, one of the first things we will see is this skeleton.
So let’s plunge.
It’s instantly, insufferably overcrowded, even hostile, in here. Everywhere we have to navigate through a dangerous scaffolding of spiky, coral-like protein formations: the neural skeleton. Though these dense formations give the neuron its three-dimensional shape, many of the skeletal parts are in constant motion—which means we have to do a lot of dodging. Millions of molecules still slam against our ship, however, and every few seconds we are jolted by electrical discharges. We don’t want to stay long.
swimming laps
We escape from one end of the neuron. Instead of perilously winding through sharp thickets of proteins, we now find ourselves free-floating in a calm, seemingly bottomless watery canyon. In the distance, we can see another neuron looming ahead.
We are in the space between the two neurons, called a synaptic cleft, and the first thing we notice is that we are not alone. We appear to be swimming with large schools of tiny molecules. They are streaming out of the neuron we just visited and thrashing helter-skelter toward the one we are facing. In a few seconds, they reverse themselves, swimming back to the neuron we just left. It instantly gobbles them up. These schools of molecules are called neurotransmitters, and they come in a variety of molecular species. They function like tiny couriers, and neurons use these molecules to communicate information across the canyon (or, more properly, the synaptic cleft). The cell that lets them escape is called the pre-synaptic neuron, and the cell that receives them is called the post-synaptic neuron.
Neurons release these chemicals into the synapse usually in response to being electrically stimulated. The neuron that receives them can react negatively or positively when it encounters these chemicals. Working something like a cellular temper tantrum, the neuron can turn itself off to the rest of the neuroelectric world (a process termed inhibition). Or, the neuron can become electrically stimulated. That allows a signal to be transferred from the pre-synaptic neuron to the post: “I got stimulated and I am passing on the good news to you.” Then the neurotransmitters return to the cell of origin, a process appropriately termed re-uptake. When that cell gobbles them up, the system is reset and ready for another signal.
As we look 360 degrees around our synaptic environment, we notice that the neural forest, large and seemingly distant, is surprisingly complicated. Take the two neurons between which we are floating. We are between just two connection points. If you can imagine two trees being uprooted by giant hands, turned 90 degrees so the roots face each other, and then jammed together, you can visualize the real world of two neurons interacting with each other in the brain. And that’s just the simplest case. Usually, thousands of neurons are jammed up against one another, all occupying a single small parcel of neural real estate. The branches form connections to one another in a nearly incomprehensible mass of branching confusion. Ten thousand points of connection is typical, and each connection is separated by a synapse, those watery canyons in which we are now floating.
Gazing at this underwater hippocampal forest, we notice several disturbing developments. Like snakes swaying to the rhythm of some chemical flute, some of these branches appear to be moving. Occasionally, the end of one neuron swells up, greatly increasing in diameter. The terminal ends of other neurons split down the middle like a forked tongue, creating two connections where there was only one. Electricity crackles through these moving neurons at a blinding 250 miles per hour, some quite near us, with clouds of neurotransmitters filling the spaces between the trunks as the electric current passes by.
What we should do now is take off our shoes and bow low in the submarine, for we are on Holy Neural Ground. What we are observing is the process of the human brain
learning
.
extreme makeover
Eric Kandel is the scientist mostly responsible for figuring out the cellular basis of this process. For it, he shared the Nobel Prize in 2000, and his most important discoveries would have made inventor Alfred Nobel proud. Kandel showed that when people learn something, the wiring in their brains changes. He demonstrated that acquiring even simple pieces of information involves the physical alteration of the structure of the neurons participating in the process. Taken broadly, these physical changes result in the functional organization and reorganization of the brain. This is astonishing. The brain is constantly learning things, so the brain is constantly rewiring itself.
Kandel first discovered this fact not by looking at humans but by looking at sea slugs. He soon found, somewhat insultingly, that human nerves learn things in the same way slug nerves learn things. And so do lots of animals in between slugs and humans. The Nobel Prize was awarded in part because his careful work described the thought processes of virtually every creature with the means to think.
We saw these physical changes while our submarine was puttering around the synaptic space between two neurons. As neurons learn, they swell, sway, and split. They break connections in one spot, glide over to a nearby region, and form connections with their new neighbors. Many stay put, simply strengthening their electrical connections with each other, increasing the efficiency of information transfer. You can get a headache just thinking about the fact that deep inside your brain, at this very moment, bits of neurons are moving around like reptiles, slithering to new spots, getting fat at one end or creating split ends. All so that you can remember a few things about Eric Kandel and his sea slugs.
But before Kandel, in the 18
th
century, the Italian scientist Vincenzo Malacarne did a surprisingly modern series of biological experiments. He trained a group of birds to do complex tricks, killed them all, and dissected their brains. He found that his trained birds had more extensive folding patterns in specific regions of their brains than his untrained birds. Fifty years later, Charles Darwin noted similar differences between the brains of wild animals and their domestic counterparts. The brains in wild animals were 15 to 30 percent larger than those of their tame, domestic counterparts. It appeared that the cold, hard world forced the wild animals into a constant learning mode. Those experiences wired their heads much differently.
It is the same with humans. This can be observed in places ranging from New Orleans’s Zydeco beer halls to the staid palaces of the New York Philharmonic. Both are the natural habitat of violin players, and violin players have really strange brains when compared with non-violin players. The neural regions that control their left hands, where complex, fine motor movement is required on the strings, look as if they’ve been gorging on a high-fat diet. These regions are enlarged, swollen and crisscrossed with complex associations. By contrast, the areas controlling the right hand, which draws the bow, looks positively anorexic, with much less complexity.
The brain acts like a muscle: The more activity you do, the larger and more complex it can become. Whether that leads to more intelligence is another issue, but one fact is indisputable: What you do in life physically changes what your brain looks like. You can wire and rewire yourself with the simple choice of which musical instrument—or professional sport—you play.