Book Excerpt 1 Keep Sharp Build a Better Brain at Any Age By Sanjay Gupta, MD Chapter 1: What Makes You You t was 1992 when I first saw a liv- ing human brain, a powerful and Ilife-changing experience for me. ABOUT THE It was, and still is, hard for me to be- AUTHOR Sanjay Gupta, M.D., lieve that so much of what we are, is a neurosurgeon and who we will become, and how we CNN’s Emmy Award– winning chief medical interpret the world resides in that correspondent. Keep Sharp, published by intricately woven bundle of tissue. Simon & Schuster in cooperation with When I am describing a neurosur- AARP, is based in part on the work of gery procedure, most people try the Global Council on to visualize what the human brain Brain Health convened by AARP. looks like, and they typically are a little off base. For starters, it doesn’t look like a dull and bland gray mass Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 2 KEEP SHARP Build a Better Brain at Any Age on the outside, despite being referred to as gray matter. It is more pinkish with whit- ish yellow patches and large blood vessels coursing on and through it. It has deep cre- vasses, known as sulci, and moun- tainous peaks, known as gyri. Deep fissures separate the brain BRAIN FACT into the various lobes in a surpris- Created by Grégory Montigny ingly consistent way. During an from the Noun Project The typical operation, the brain pulsates gen- human brain tly out of the skull’s borders and comprises looks very much alive. Consisten- about 2 to 2.5 percent of the cy wise, it is not so much rubbery body’s total as squishy, more like gelatin. It weight but has always amazed me how frag- uses 20 per- ile the brain is despite its incredi- cent of its total energy and ble function and versatility. Once oxygen intake. you see the brain, you very much want to protect it and take care of it. To me, the brain has always been a bit mystical. Weighing in at a little over three Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 3 KEEP SHARP Build a Better Brain at Any Age pounds, it comprises all the circuitry we need to do just about everything. Think about that for a moment: It weighs less than most laptop computers, yet it can perform in a way that no computer can or will ever rival. In fact, the oft-cited meta- phor of brains being like computers fails in oh-so-many ways. We may speak in terms of the brain’s pro- cessing speed, its storage capacity, its cir- cuitry, and its encodings and encryptions. But the brain doesn’t have a fixed memory capacity that is waiting to be filled up, and it doesn’t calculate in the manner a com- puter does. Even how we each see and perceive the world is an active interpretation and re- sult of what we pay attention to and antic- ipate—not a passive receiving of inputs. It is true that our eyes see the world upside down. The brain then takes the input and Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 4 KEEP SHARP Build a Better Brain at Any Age converts it into a coherent image. In addition, the back of the eye, the reti- na, provides the brain with two-dimension- al images from each eye, which the brain then converts into beautiful, tex- tured three-dimensional images, providing depth perception. BRAIN FACT And we all have blind spots in Created by Grégory Montigny our vision that our brain con- from the Noun Project Your brain is stantly fills in using constant data roughly 73 per- you probably didn’t even realize cent water and you were collecting. No matter it takes only 2 percent how sophisticated artificial intelli- dehydration to gence becomes, there will always affect your be some things the human brain cognitive skills, can do that no computer can. so drinking just a few ounces Compared to other mammals, of water can our brain’s size relative to the rest reverse that. of our body is astonishingly large. Consider the brain of an elephant: It takes up 1/550 of the animal’s total weight. Our Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 5 KEEP SHARP Build a Better Brain at Any Age brain, on the other hand, is about 1/40 of our body weight. But the feature that most sets us apart from all other species is our amazing ability to think in ways that reach far beyond mere survival. Fish, amphibians, reptiles, and birds, for instance, are assumed not to do much “thinking,” at least in the way we conceive of it. But all animals concern themselves with the everyday business of eating, sleep- ing, reproducing, and surviving—automatic instinctual processes under the control of what’s called the “reptilian brain.” We have our own inner primitive reptilian brain that performs the same functions for us, and in fact it drives much of our behavior (perhaps more than we’d like to admit). It is the com- plexity and large size of our outer cerebral cortex that allows us to perform more so- phisticated tasks than, say, cats and dogs. Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 6 KEEP SHARP Build a Better Brain at Any Age We can more successfully use language, acquire complex skills, create tools, and live in social groups thanks to that bark-like lay- er of our brain. Cortex means bark in Latin, and in this case, it is the outer lay- er of the brain, full of folds, ridg- es, and valleys. Because the brain BRAIN FACT folds back on itself over and over Created by Grégory Montigny again, its surface area is far larger from the Noun Project Your brain than you might guess—a little over weighs a two square feet on average, though little over 3 exact calculations do vary (e.g., it pounds. Sixty percent of the would spread out over a page or dry weight is two of a standard newspaper). And fat, making the probably somewhere deep in those brain the crevasses is likely the seat of con- fattiest organ sciousness. Heady stuff! in the body. The human brain contains an estimated (give or take) 100 billion brain cells, or neurons, and billions of nerve fi- bers (although nobody knows these num- Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 7 KEEP SHARP Build a Better Brain at Any Age bers exactly for sure—because exact cal- culations are impossible as of yet). These neurons are linked by trillions of connec- tions called synapses. It is through these connections that we are able to think abstractly, feel angry or hungry, remember, rationalize, make de- cisions, be creative, form language, remi- nisce about the past, plan the future, hold moral convictions, communicate our inten- tions, contemplate complex stories, pass judgment, respond to nuanced social cues, coordinate dance moves, know which way is up or down, solve complex problems, tell a lie or a joke, walk on our tiptoes, notice a scent in the air, breathe, sense fear or dan- ger, engage in passive-aggressive behav- ior, learn to build spaceships, sleep well at night and dream, express and experience deeply felt emotions such as love, analyze information and stimuli in an exceptionally Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 8 KEEP SHARP Build a Better Brain at Any Age sophisticated fashion, and so on. We can do many of these tasks at the same time, too. Perhaps you’re reading this book, drinking a beverage, digesting your lunch, plotting when you’ll get to your cluttered garage this year, thinking about your week- BRAIN FACT end plans (“in the back of your Created by Grégory Montigny mind”), and breathing, among from the Noun Project All brain cells many other things. are not alike. Each part of the brain serves There are many a special, defined purpose, and different types of neurons in these parts link together to func- the brain, tion in a coordinated manner. each serving That last part is key to our new an important understanding of the brain. function. When I was in middle school, the brain was thought to be segment- ed by purpose—one area was for abstract thought, another for coloring within the lines, yet another for forming language. Excerpted from Keep Sharp: Build a Better Brain at Any Age by Sanjay Gupta, MD (Simon & Schuster), an AARP-branded book 9 KEEP SHARP Build a Better Brain at Any Age If you took high school biology, you may have heard the story of Phineas Gage, one of the most famous survivors of a serious brain injury. You may not know, however, just how much his unfortunate accident il- luminated for scientists the inner workings of the brain at a time long before we had advanced techniques to measure, test, and examine brain functions.