CHAPTER 3
DUELING BODY MAPS
or, Why You Still Feel Fat After Losing Weight
Have you ever seen a fat person who was comfortable in his or her own skin? Think of Jackie Gleason high-stepping across a stage like a tutu-clad hippo on pointe. If you’re too young to visualize the inestimable Gleason, consider the contemporary American comedian Jack Black, who, despite a propensity to chubbiness, moves gracefully, athletically, self-lovingly around a movie set.
And now consider talk show megastar Oprah Winfrey before and after her lionhearted battle with yo-yo dieting. She reveals the whole story in a video, Make the Connection—how for twenty years she lived her life unconsciously, how she felt out of control, ashamed, lonely, filled with self-loathing. Afraid to confront her traumatic past, she ate compulsively to dull the pain. Once, sitting near ringside watching Mike Tyson in a world heavyweight championship fight, she was shocked to realize that they both weighed the same—216 pounds. So she starved herself, dropping 67 pounds. And then ballooned back up to 226 pounds.
Famously, in 1992, Oprah decided she had to take control of her life. With the help of a professional trainer, Bob Greene, she began a daily regimen of intense aerobic exercise plus a low-fat diet. The rest is history. As chronicled on her television shows, books, and videos, Oprah conquered her weight problem, with occasional minor backslides, through vigorous physical conditioning, hard work, and determination.
No doubt the exercise played a major role in Oprah’s weight loss. But there is another explanation for her success that has never been brought to light. Apart from all that time spent in the gym, the 6 A.M. workouts, the sweat and suffering, the weaning from deep-fry and chocolate, her transformation can also be described as a story of dueling body maps, of how she used one body map to remodel a second body map.
To understand how this works, you need to understand the nature of both maps. One, called the body schema, is a felt sense based on physical properties of your body. The second, the body image, stems from learned attitudes about your body.
The Body Schema
You already know about your body maps, à la Penfield, based on touch. You have sensors all over your body surface that are responsive to gentle caresses or pressure or pain or heat or cold. But there are two other ingredients to your body’s felt sense, or body schema, that operate almost entirely outside consciousness. And while scientists have known about these sensory channels for decades, they are only now being traced to specific regions of the brain. One reads signals from inside your body. The other reads signals from your inner ear to give you a sense of balance.
Take a moment to form a mental picture of your body’s muscles, bones, joints, and tendons. These tissues are endowed with specialized receptors that detect tiny movements—the twitch of a muscle fiber, mechanical stress on a bone, angular rotation of a joint, or stretch of a tendon. Whenever they sense change, these sensors send the information up to your brain to update your sense of where you are in space and how your body is configured. The signals are first mapped in your primary touch map, then branch and filter upward through other, higher-order maps in your body mandala. These maps guide your body movements and expectations about those movements.
The weight of your body and its postures are calculated by these sensors, providing what is called proprioception, meaning “perception of one’s own.” If you fail a sobriety test—you can’t walk a straight line or touch your finger to your nose—it’s because your sense of where you and how your limbs are located in space is impaired. During growth spurts, some children and teenagers temporarily lose this body sense and feel as if their feet or legs are missing. When you learn a new skill or sport, you re-hone this body sense through practice.
Your body schema is also informed by a library of what many people call “muscle memories,” although the term is rather inaccurate. These memories actually reside in the brain’s motor maps, not down in the muscles proper, as the term would seem to suggest. These muscle memories give you an intuitive understanding about how your body is able to move and what it is capable of. This implicit knowledge includes things like how far you can bend over, what parts of your back you can reach with your hands, and which objects on the dinner table are within arm’s reach without leaning. The vast majority of these understandings and judgments are unconscious. Your body mandala is constantly computing them and using them to update your schema. (Just to be clear on the distinction, your body mandala is the physical network of body maps in your brain; your body schema is the felt experience of your body constructed by these maps.)
OFF OUR ROCKERS
Of all your body senses, the one you tend to underappreciate most is your sense of balance. You only pay attention to it if you happen to lose it, which for most people is a rare happenstance. Miss that last step, spin yourself around, jump from a dock onto a bouncy boat, and you’ll feel a sudden loss of balance. But then, if all goes well, you’ll regain it in an instant. Of all your senses, balance is the most intangible. You can point to eyes, ears, skin, and other organs to explain the five primary senses, but balance is somehow different. It’s difficult to bring whatever “balance” is into consciousness by thinking about it. You can never switch it off. It’s just there.
Balance is with you constantly because balance is all about dealing with gravity. From the moment you exit the warm floating world of your mother’s womb, you are bathed in the force of gravity. Gravity exerts an attractive force on your body every living, breathing moment of your life.
In the beginning, you are helpless against it. But as you gain control over your limbs, you find that you can roll over and—voilà!—sit up. You start balancing your body. Nobody builds a two-legged chair, because it’s not stable, but you, as a human, learn to walk on two legs by calibrating Earth’s gravity with your head, body, and limbs. Soon you are off and running.
Balance is achieved by integrating numerous brain maps, but one you may not know much about is called the vestibular system. Just as you have eyes for seeing and ears for hearing, you have three little canals, tiny stones, and “hairs” inside your inner ear that specialize in detecting gravity and acceleration.
The canals, or semicircular canals, are fluid-filled tubes that lie on three axes—up and down, left and right, forward and back. As you move your head, the fluid sloshes around in the canals, and tiny sensors, called hair cells, pick up the direction and speed of movement. Your brain uses this information to develop a clear model of the world in three dimensions and to figure out where your head is moving in relation to gravity.
Of course you don’t achieve balance with your head alone. Vestibular signals are integrated with other sensory systems for you to have a functioning whole body schema. For example, vestibular signals go to your eyes. This is why you can shake your head while reading this page and still track the words. Your eyes work with vestibular information to correct for your head movements.
Vestibular signals are intimately tied to touch. Try this little experiment: Stand next to a wall on one leg, let your arms dangle, and close your eyes. See what happens. Now assume the same posture, touch the wall with the tip of one finger, and close your eyes. See what happens this time.
Nothing stabilizes balance better than light touches and contact with the environment.
Vestibular information also goes to vomiting centers in your brain stem and up to higher brain areas involved in body perception, self-motion, the space around your body, and that biggie, self-awareness.
As you know from experience, balance is dynamic. Gravity is constant, but you are recalibrating all the time.
When astronauts return from space and do deep knee bends, they get the feeling that the ground is rushing up under their feet. Their brains have adapted to zero gravity and need time to adjust.
When you are on a boat all day, bobbing up and down on the waves, you may feel wobbly back on land because your vestibular system is still tracking the motion. Some people get motion sickness due to a highly sensitive vestibular system.
But people who gradually lose their vestibular organs as a result of injury or disease will never, no matter how hard you try to make them, be motion sick. They can navigate, but must rely on vision and pressure on their feet to calibrate balance, although they have trouble walking on sand or in the dark.
But the most common reason people lose their sense of balance is aging. All brain systems decay with age, along with failing eyes and diminished hearing. But there are ways to reverse wobbly postures: Treat the bottoms of your feet.
The soles of your feet have touch receptors that send signals up to your brain every time you stand and put pressure on the ground. These signals are combined in higher brain maps with vestibular, visual, and other touch information to keep you nimble on your toes.
But these foot signals can blur as receptors become less sharp with age. Diabetes and poor blood flow can deaden the foot. You begin to sway. But as James Collins, a biomedical engineer at Boston University, discovered, if you add a faint vibration to the bottom of the foot—he invented insoles that do just that—your brain will automatically pick up degraded signals from your feet. With his insoles, eighty-year-olds can stand as straight as thirty-year-olds.
You don't necessarily need electronic gadgets to keep your vestibular system in tune, however. Walking on cobblestones is a low-tech, proven route to the same end. Studies in Europe have shown that balance deteriorates more slowly in elderly people who walk regularly on cobblestone than in those who use only modern sidewalks. The Chinese have known about this for centuries. Go to almost any park in any city in China, and you will find thousands of cobblestones laid out in lovely patterns on the ground. People take off their shoes and walk on the stones to achieve better health. The science of body maps explains why it works.
You also have special receptors within each ear that are sensitively attuned to where your head is with respect to gravity, three-dimensional space, and motion. When you walk down the street with your head bobbing up and down, you can still read signs on buildings thanks to this so-called vestibular system. When you feel dizzy or nauseated on a rough boat ride through choppy seas, it’s because signals from these receptors have reached your conscious awareness. In your brain, two small areas combine this gravity-sensing system with input from your eyes and body so that you know where you are at all times.
Your body schema is a physiological construct. Your brain creates it from the interaction of touch, vision, proprioception, balance, and hearing. It even extends it out into the space around your body. You use it to help locate objects in space or on your body—to swat a mosquito on your arm, to grasp a doorknob, or duck out of a dodgeball’s way.
Again in your imagination, put out your hand, palm up, fingers pointed straight ahead. Now rotate your hand until your fingers point to the right. Rotate it again, fingers pointing to the left. You can do these movements without vision because you have an online mental representation of your body. When you reach out to grasp a coffee cup, you don’t have to think about where your hand is or where it is headed. Your body sense automatically plans and directs the movements. When in the middle of the night you grope your way to the bathroom, your body sense guides you there.
Your schema is updated constantly by the flow of sensation from your skin, joints, muscles, and viscera. Your continuous sense of inhabiting a body embedded within a larger world stems in large part from this mental construct.
Moreover, you are rarely aware of sensations from your body. They occur automatically. While you can close your eyes and cover your ears, you can’t turn off your body sense. If you are born blind, other senses can compensate for vision. But if you were born without receptors that map your body, you would not know you had a body.
Loss of proprioception in adulthood is rare, but it has happened. For example, in 1972 a nineteen-year-old Englishman named Ian Waterman contracted a rare disease. While the nerves that carry information from his brain down to his body, instructing it how to move, were intact, the nerves that carry information from his body back up into his brain were destroyed. Imagine how this feels. Waterman can see but not feel where his body is located, whether he is moving or not moving. At first he was a mess, like a living rag doll. Gradually, he taught himself to move again by watching and guiding his actions visually. But the second he closes his eyes, he collapses in a heap.
The idea of the body schema was first proposed in 1911 by two British neurologists, Sir Henry Head and Gordon Holmes. Head and Holmes figured out that, like touch information, signals from your body’s musculoskeletal system are carried into your brain to determine your posture and the position of your limbs. According to Head, we build up internal postural models of ourselves in conjunction with models of the surface of our bodies. He dubbed this the body schemata (now just called body schema), defined as “organized models of ourselves.”
Head and Holmes also realized that, wondrously, your body schema expands with the clothes you wear.
“Anything which participates in the conscious movement of our bodies is added to the model of ourselves and becomes part of the schemata,” Head wrote. Thus, “a woman’s power of localization may extend to the feather in her hat.” In Sir Henry’s day, the Edwardian era, women wore hats with wide brims and large swoopy feathers. The feather, he observed, was incorporated into the woman’s body schema.
The next time you see a person wearing a cowboy hat, watch how he ducks down when he passes through a doorway. Better yet, if you have a Stetson or can borrow one, try it yourself. Walk through a door and notice your posture. Did you stoop down ever so slightly? Unless you are very tall, the hat probably cleared the doorframe with inches to spare. Yet you still felt the need to bend your knees or duck your head. A hat is an inanimate object. Yet you act as if it were a part of your head. As far as your body schema is concerned, it is part of your body. If you wear the hat regularly, you will gain precise though largely unconscious knowledge of its height and width, and will pass through doors with an automatic, tiny tilt of your head that’s just right to miss the doorframe by a hair.
ILLUSIONS OF THE BODY
Your body schema feels reliable and stable most of the time, so you may be surprised at how mutable it can be under the right conditions. Using certain tricks, you can induce somatic illusions to make parts of your body feel like they are growing, shrinking, bending, embodied in foreign objects, or otherwise warped or displaced in impossible ways. Armed with these illusions, you can be the life of the party—but bear in mind, some people are immune to them. They will miss out on the fun.
A whole family of these tricks involves the use of small vibrators, or buzzers, that can be taped or held against your body. (Researchers often use standard 100 Hz physiotherapy vibrators, but many kinds of small personal massagers should work.) The buzzers work by confusing the stretch-sensing fibers, called muscle spindles, in your muscles. Spindles sense the length, and changes in length, of your muscles. Their constant reporting to your brain plays a vital role in your body schema.
Like all the senses, proprioception is fallible. The vibrations “fool” your muscle spindles into informing your body maps that the tendon is slackening. At the simplest level of interpretation, this corresponds to the feeling that the joint is bending, even though it isn’t. You have a discrepancy between what you see and the proprioceptively sensed position of your limb.
But simple bending isn’t the only illusory sensation buzzers can fabricate. The brain is a very clever and willing rationalizer. When combined with other sensory signals that don’t jibe with the tendon-stretch information, rather than conclude that that information is faulty, your body mandala will try to come up with an integrated interpretation, even if that interpretation is physically impossible.
Here’s one of the simplest examples. Tape a buzzer to your triceps tendon, lean against a wall with just that arm, and close your eyes. You soon feel that your arm is growing longer, and your head feels as if it’s moving away from the wall! Now tape the buzzer to your biceps tendon (in the crook of your elbow), and you get the opposite sensation: Your arm feels as if it’s shrinking. If you wait long enough, you may even feel your forehead tingle with anticipation as it passes ghostlike through the wall. Of course, in reality, your arm and body are motionless, as you can confirm by opening your eyes at any point.
Or consider the Pinocchio illusion. Tape a buzzer to the biceps tendon, touch your index finger to your nose, and close your eyes. It feels as if your nose is growing two feet long! Here’s why: Your body mandala needs to reconcile two contradictory pieces of data. Your finger is in constant contact with the tip of your nose, and your elbow is extending away from your face. The best-fit rationalization is that your nose is magically lengthening.
Next consider the shrinking waist illusion. Tape a buzzer to each triceps tendon, put your hands around your waist, and look up at the ceiling. After a few moments, you will feel your waist begin to shrink! It draws closer and closer toward a point in the pit of your stomach. You expect your fingers to meet each other in front and your thumbs to touch behind your back, but because your waist isn’t actually shrinking, they never do. (Sorry, miracle diet seekers.)
You get the idea. The list of buzzer-based illusions goes on. If you vibrate both your Achilles tendons, you will feel that you’re pitching forward on rubbery ankles. Vibrate the muscles at the base of your neck, and you’ll feel as if your head is swiveling into an anatomically impossible position, looking back, like a ghoul in a horror film.
And if you don’t mind being in a pitch-black room, you can, with the help of a friend, try this little experiment on yourself. The room must be utterly dark. (Another great place to try this is inside a cave where there are no photons whatsoever.) Stand in a comfortable position and wave your hand in front of your face. You will have the powerful impression that you can see your hand. Now lower your hand and ask your friend to wave his hand in front of your face. You will not be able to see it. The reason? When you move your own hand, the multisensory part of your brain that combines movement and vision is activated. An accurate visual prediction of your hand’s movements percolates through your body mandala into your visual centers, creating the sightlike experience in spite of the darkness. But when your friend moves his hand, your visual areas are not co-stimulated. You may imagine in your mind’s eye what your friend’s hand must be doing out there in the dark, but the experience is not at all the same.
Other illusions don’t require you to close your eyes, such as the doorframe illusion children around the world enjoy at slumber parties. Stand in a doorway and press the backs of your wrists outward against the frame as hard as you dare for thirty seconds or so. Then relax your arms, step forward, and it feels as if your arms are being levitated.
But this is child’s play, a super-low-tech way of fatiguing your proprioceptors. Some of the most interesting somatic illusions involve the combination of vision and somatic sensation, which happens in the posterior parietal lobe. Let’s consider two of them:
First, imagine a periscope tube that hangs from the ceiling and snugs down over your head like a helmet. But unlike the periscope in a submarine, you keep your hands in your lap and can pivot your view simply by turning your neck. Furthermore, this periscope is rigged up in an unusual way: For every one degree your neck turns, your view rotates by two degrees. Thus, at the extreme, if you turn your head all the way to the left or the right, you actually end up seeing the view behind you. What do you experience wearing this thing? It’s called the rubber-neck illusion: It feels as if your neck has become twisty like an owl’s. Building one at home is probably beyond most readers, though it’s entirely possible to do.
Finally, one more great illusion that you can more realistically perform at home is called the rubber-hand illusion. What you need is a fake hand (from a mannequin or a Halloween store, for example), a freestanding cardboard partition, a table, two chairs, and a friend. Sit down and lay the rubber arm facing away from yourself, palm down, on the table in front of you. Lay your real hand palm down next to it, making sure the orientation of both hands is the same. Now place the partition between the two hands, hiding your real hand but leaving the false one in plain sight. Next, have your friend sit down at the other side of the table and gently manipulate both hands in the same way with identical timing while you watch the fake hand. For example, on both hands your friend taps the third knuckle twice, then drums her fingers on the pinky finger joint, then makes a long stroke down the length of the index finger, and so on. Soon, if you’re like the majority of people, you will feel those sensations coming from the false hand!
The kicker is that the fake hand prop is not really needed. You can sometimes get the same illusion—if not always as vivid—using other objects that only vaguely or abstractly resemble a hand, such as a small kitchen broom or a twig from a tree. You may even do it with no fake hand at all, just the table-top.
How does it work? Visual and tactile stimulation converge in combined vision and touch maps in your posterior parietal lobe, and because they are well correlated in time, those maps will accept the interpretation that the tactile sensations are actually coming from the inanimate thing you are watching.
Interestingly, people show different degrees of ability to experience this illusion. Some people feel it vividly and almost instantly, while others take a long time to start experiencing it and may “lose the feel” for it. Neuroscientists are just starting to search for the basis of these individual differences, which may end up having practical implications for prosthetics, virtual reality, neurotherapy and rehabilitation, and anorexia treatment; anorexics are immune to the rubber-hand illusion.
When you work with instructors of dance, yoga, tai chi, Pilates, Alexander Technique, Feldenkrais, or dozens of other kinds of movement training, you are basically working on body schema awareness. These methods teach you to purposefully attend to the many core elements of your schema as a means of self-exploration.
Personal trainers say that they can often identify thin people who were previously overweight, noting that such individuals still have the body language of a fat person, with shoulders forward, head tilted down, legs slightly splayed. Their walk is heavy, their movements cumbersome. On the other hand, a fat person can have the body language of a ballerina, with a straight back, erect shoulders, lightness of step, and fluidity of motion.
Finally, your shadow binds extrapersonal space to your body, which is why many people are superstitious about stepping on shadows. As far as your brain is concerned, your shadow is a part of your body, as real as skin. If you walk down a path with your eyes down and a shadow looms into your peripheral vision, your brain sounds the alarm. Your space is being invaded. Time to pay attention.
A Paean to the Parietal Lobe
To better understand how your body schema emerges, it is helpful to know a little bit more about your parietal lobe. If you place your hand toward the back of your head and over your ear, your parietal lobe is beneath your hand. This area’s upper rear sector, called the posterior parietal cortex, is chock full of maps of your body and the space around your body. Like the mighty Mississippi, it lies at the confluence of several great tributaries. Highly processed information converges in the posterior parietal from all your major senses—touch, proprioception, vision, hearing, and balance—plus a constant stream of information about movements and action plans flowing in from your frontal motor maps. Probably more than any other region of your brain, this area constitutes the center of your embodied self embedded in a wider world. Here is where your body schema, sense of balance, and feeling of physical wholeness “come together.” Parietal neurons are not concerned with identifying things in terms of their names, identities, or meanings. Rather, they are concerned with the composition of space and your body’s relationship to its surroundings.
Many of the maps in the posterior parietal cortex represent your body in different coordinate systems, or frames of reference. Some maps “think” in head-and-neck-centered coordinates; some are trunk-centered; some are arm-and-shoulder-centered; some are eye-centered; some are hand-centered; some are whole-body-centered. Your parietal lobe juggles these many coordinate systems, all the while keeping them tightly integrated with the activity of your motor maps, to produce the impression that your body is whole and unified in purpose. It creates your (usually) seamless understanding of where you are in the world and how you relate to it. That last point is worth emphasizing: The mental map you keep of the world around you is represented not in dry, referenceless, x-y-z coordinates, but in terms of your bodily relation to it.
It is amazing enough to know that this system works during a mundane action like getting up off your sofa and heading for the kitchen to start dinner. At the height of human skill and talent it is even more astounding. Imagine soccer star Mia Hamm in the thick of a skirmish. She is hurtling toward the other team’s goal just a few meters ahead. She is running and dribbling the ball between her feet. She is so well trained and talented, the ball is at one with her inside her peripersonal space, as integrated into her body mandala as her own feet. She knows the ball’s position and speed each fraction of a second. All around her are other players running in different directions at different speeds. A few of them are closing in fast. She feels it the instant they penetrate her peripersonal space. Her eyes sweep the field. Her head and body pivot, and the balance organs in each inner ear send precise information about the angle, velocity, and acceleration of her head into her vestibular cortex, where it is immediately integrated in her body schema. Her arms arc and twist to keep her balanced. Her legs dance. Her feet sense the texture of the grass beneath her. She hears other people’s footfalls and heavy breathing as well as her own. In a split second she sees an opportunity. For another split second the motor intention forms in her parietal and motor body maps, and with a deft kick the ball rockets off toward its target.
Body Image
So here’s an interesting question. Let’s say you go on a diet and lose twenty-five pounds. You are thinner. Your thighs are less bulky. You don’t feel your legs pinching the seams of your too-snug jeans or that roll of fat over a tight waistband. Your belt is a notch smaller. Given the fact that your body schema arises from the motion of your body as it makes contact with clothes and other objects, shouldn’t it reflect the fact of your hard-won thinness in the way you feel and perceive yourself? Shouldn’t you now be getting constant signals telling you that you are svelte? Shouldn’t you feel less fat?
But as most yo-yo dieters can attest, at some deep level you have not changed. Mysteriously, you still feel fat. As you gaze in the mirror at your newly trimmed-down body, something is giving you a different message.
That something is your body image. In the world of weight loss advice, body image is often mentioned but rarely explained in ways that can help you keep off excess pounds. In contrast to your body schema, which is mostly unconscious, your body image is the more conscious perception of your body: how you see yourself and how you present yourself to the world. It is not about being tall or short, fat or skinny, good-looking or homely. It is about your attitudes toward those traits in yourself, your emotional response to how you experience your body, including how you dress, pose, move, and believe others see you.
Like your body schema, body image has its basis in many of your brain’s body maps. But there are some important differences that explain why diets often fail. Your body schema is more confined to specialized circuits, while the ingredients for your body image—which include the beliefs you have about your body—are spread more widely throughout your brain, wherever memories are stored. Beliefs are ultimately as tangible as the cells in your brain, because that is where beliefs are created, stored, and, with new information, updated or reconsolidated. Beliefs are embedded in the physical interconnections between neurons, which are organized by experience into stable networks. Beliefs are held in brain circuits that fire in response to your expectations and predictions about how the world operates.
To grasp how this works, you need to know a bit more about how the brain is organized. Almost all of your higher mental functions are carried out in the cortex—a thin sheet of tissue that is wrapped around older brain structures. About the size of a formal dinner napkin, it is massively folded so it can fit inside your skull. The entire cortical sheet has six layers of cells, each as thick as a single business card.
FAT
People are overweight for many reasons. They have fat parents, eat terrible diets, and don’t exercise. Their bodies—actually their gut bacteria—are super-adept at absorbing calories. They watch a lot of television with ads that depict heaping portions of high-calorie food and come to see those amounts as normal. They are too poor or overworked to join a gym or buy fresh fruits and vegetables. They overeat because they were abused, physically or emotionally, and food alleviates their pain. They feel an emptiness inside and reach for food to fill it.
Actually, food is addictive in the sense that heroin is addictive. Like drugs of abuse, the sight or smell of food increases levels of a brain pleasure chemical called dopamine. But like drug addicts, many obese people have a relative dearth of dopamine receptors, which makes them more sensitive to the reward properties of food. The brain’s pleasure circuitry can be co-opted by many stimuli, such as cocaine, gambling, sex, or food.
One study of obese people found that a sensory region of the brain devoted to mapping the mouth, lips, and tongue is overactive. Thus they may get extra pleasure from eating.
A study of craving, or an irresistible urge to consume, found a specific pattern of activity in the brain’s frontal lobes. The cravings could be suppressed by zapping these regions with a special magnet.
Although the cortex physically resembles a thin sheet, it is functionally organized into regions that specialize in different tasks, such as vision, hearing, touch, movement, and making plans. Furthermore, these regions are organized in hierarchies. Imagine a deck of cards laid out, faceup, side by side. Functionally the ace is higher than the jack, which is functionally higher than the eight, which is functionally higher than the two. The functional hierarchies in your brain are far more complex than playing cards, but the analogy should give you an idea of how hierarchies can exist in a nearly two-dimensional plane.
In the cortex, so-called lower areas absorb raw sensory information and pass it over to higher areas where it is processed and then passed over to still higher areas. But there is no ultimate top area where everything “comes together” (remember the “homunculus fallacy” from chapter 2). On the contrary. Once information reaches higher regions, it is fed back down the hierarchy. Anatomists have found that in most areas of the cortex, for every fiber carrying information up the hierarchy, there are as many as ten fibers carrying processed information back down the hierarchy.
Researchers are still exploring the meaning of this massive feedback architecture, but one function is now clear: Your mind operates via prediction. Perception is not a process of passive absorption, but of active construction. When you see, hear, or feel something, the incoming information is always fragmentary and ambiguous. As it percolates up the cortical hierarchy, each area asks: “Is this what I expect? Is this what I predict? Does this conform to what I already know is the case?” So your brain is constantly comparing incoming information to what it already knows or expects or believes. As higher areas make sense of the input—“Yes, this is something I have seen before”—the information is fed back to lower areas to confirm that what you believe is happening really is happening.
But in many cases it goes beyond mere confirmation, and the back-fed prediction or belief actually alters the upward-flowing information to make it conform. The fact that the information travels “backward” down the cortical hierarchy all the way from higher, mentally sophisticated regions into lower levels of basic sensory processing means your predictions and beliefs can work against you. They do this by interfering with your ability to see things afresh, or even notice major contradictions between your expectations and what is actually present to your senses. For example, pity the ubiquitous husband who totally fails to notice that his wife has come home with a new hairstyle.
In other words, your understanding of reality is a far cry from reality itself. Your understanding of reality is constructed in large part according to your expectations and beliefs, which are based on all your past experiences, which are held in the cortex as predictive memory. This is worth repeating: Many of your perceptions—what you see, hear, feel, and think is real—are profoundly shaped and influenced by your beliefs and expectations. And this includes beliefs about your body.
The term “body image” was introduced in 1935 by Paul Schilder, an Austrian American neurologist who felt that the body schema concept did not capture the full nature of bodily experience. The body image, Schilder said, refers to the mental pictures we have of our bodies or the way our bodies appear to us. If you added a pair of cowboy boots and a turquoise belt buckle to that Stetson, you would have a distinctive body image. As a psychological construct, it is the set of beliefs you hold about yourself. (Maybe this is why Halloween is such a popular event in our culture. You get to dress up in outrageous costumes and change your body image, if only for one night a year.)
Your body schema and your body image both evolve as you grow up. The changes in the schema are pretty universal. Your arms get longer. Your reach is greater. Your legs lengthen. Your center of mass rises. Your stride increases. Your proportions fall into place. Hormones kick in. Girls grow breasts. Boys bulk up.
But while the schema is largely a function of body parts in motion, your body image draws on a larger web involving your lifetime’s library of personal experiences and memories. Your body image is an amalgam of beliefs—attitudes, assumptions, expectations, with an occasional delusion thrown in—that are likewise embedded both in your body maps and in the parts of your cortex that store your autobiographical memories and social attitudes. Your family, peers, and culture provide the content; you provide the interpretation.
For most people, important beliefs about the body begin to bubble into consciousness in early adolescence. By the end of the teenage years, these beliefs have congealed into a coherent body image, right along with religious beliefs, political attitudes, and stereotypes. All are highly resistant to change later in life.
Now, it would be great if typical adolescents had body image experiences that resulted in boys and girls saying to themselves, “I am lovable. I have a very nice body that encompasses the real me. I am happy with the way I look.” But teens hold all sorts of unhealthy beliefs about their bodies: “I am too fat.” “I am not muscular.” “My ears are freakishly huge.” “I am flat-chested.”
And for people like Oprah, who experienced sexual abuse in childhood, the body image can be drenched in shame. Such wounds are deeply buried and soothed by comfort foods far into the night.
BODY IMAGE AND CULTURE
Not all cultures promote thinness for women. In Belize, there are two ideal body types for women. You can be shaped like a bottle of Coke with hourglass curves, or you can resemble a bottle of Fanta with less at the top and more at the bottom. For women in Belize, shape is more important than size, and it’s shape, not size, that they dress to accentuate. Little girls are given these words of advice: “Never leave yourself.”
Similarly, not all cultures promote muscularity for men. A Harvard psychiatrist, Dr. Harrison Pope, recently developed a computerized measure of body image perception called a somatomorphic matrix. A subject sees an image of a male body that he can adjust on a computer screen through ten levels of muscularity and ten levels of fat, for a total of one hundred images. He is asked to choose the images that best match his own body, the body of an average man his age in his own country, and the body he thinks that women would prefer.
American, French, and Austrian men picked an ideal body image that was twenty-eight pounds more muscular than themselves. In fact, the women preferred a male body size that was much closer to that of the average man, with little added muscle. Taiwanese men, on the other hand, rarely wanted to be more muscular. Asked what women like, they said, “Someone who looks like me.”
If you lose weight and still feel fat, it may be because of a gaping mismatch between your body image and your body schema, which is a reflection of the body proper. Your body schema has drifted remarkably out of touch with your body image, and you experience an internal psychic disconnect. Your body image is dueling with your body schema. Your beliefs about your body are out of sync with what your body maps or even your eyes are reporting to you. And being at war with yourself, even when it is all happening beneath the level of your conscious awareness, is a miserable experience.
Like your political and religious beliefs, your attitudes about your body are obstinate, headstrong, all but immutable. When you learn that a trusted politician has been lying to you for years, you don’t switch parties. When you find out that intercessory prayer does not make people heal faster, you don’t stop praying or give up religion. And when your body schema gives you different, thinner signals about your body size, you don’t give up your beliefs about your body.
CULTURAL EFFECTS
Cultural beliefs can also produce pathological changes in body maps. For example, koro is seen in parts of Asia and Africa. It begins when a man who is emotionally upset goes to urinate and observes that his penis is becoming smaller. He grabs his genitals before they can retract into his body and he runs for help. Those afflicted with koro believe that their penis is shrinking, and that when it disappears, they will die. Epidemics have occurred in Singapore, Indonesia, and China. In Senegal, foreigners have been accused of being penis shrinkers. A handshake is all it takes.
In Japan, people suffer from a syndrome of intense fear that one’s body, body parts, or bodily functions are displeasing, embarrassing, or offensive to other people in appearance, odor, facial expressions, or movements. It is a motivation for suicide.
Koreans can suffer from hwabyung, in which victims complain of a periodically rising abdominal mass and sense of dying from asphyxiation. Nigerians complain of extreme heat in their heads when they feel anxious, whereas Cambodians suffer painful neck tension, ringing in the ears, and body weakness, called “wind overload,” when they are stressed. Such symptoms are related to cultural beliefs about which body systems are most vulnerable in a person.
Recall that your body schema is composed of dynamic sensory signals flowing through your body mandala, plus a database of muscle memories distributed among your body maps. As your skin rubs against your clothes in a smaller size, you have a new set of information about your proportions. You have to work less hard to lug your body around your house, which also testifies to the changes you’ve achieved. But your belief-ridden body image has not changed. Beliefs can be enormously potent, potent enough to drown out your new-felt body sense. If only the “thin person screaming to get out” of the fat body could triumph. But the reverse is more often the reality: A fat body image trapped inside a slimmed-down body wins the conflict. Being thinner hasn’t solved your problems. All the psychological reasons you have for overeating have not gone away. You overeat because you hate yourself and you hate yourself because you overeat. Such is the recipe for yo-yo dieting.
Fortunately, there are ways to break the cycle. The thin person screaming to get out of the fat person is actually your body schema, masked and muted beneath a rubble pile of false belief. The trick is to find ways to listen to that person.
The Wisdom of Wobble Boards
Now, you could spend years in talk therapy, Woody Allen style, combing through your past, getting to the bottom of your painful feelings, poking holes in your self-hatred. But talking about your problems is not a good way to get in touch with a body schema that has been trumped by die-hard beliefs. You need to try something more direct, more dynamic, more tactile, more proprioceptive, more vestibular. More to do with body maps than with strolls down memory lane.
Jeff Della Penna, a personal trainer in Santa Fe, New Mexico, has two primary goals for his clients. One is for them to get in touch with their body schema—to learn to feel their muscles without straining, sense the movement of their joints, and balance while standing on a wobbly board. Second, have fun. Enjoyment is essential to a good workout, he says, and so Della Penna often takes his clients on hikes and adventure trips where they get constructive aerobic exercise.
Many of Della Penna’s clients are overweight. They come for help, he says, because they’ve hit three hundred pounds, have dangerously high blood pressure, or can no longer walk up their front steps. They are very frightened. Most of them tell Della Penna that they can trace their weight problem to some traumatic event in their lives—a death, an accident, an abusive childhood, or the like. For many years they have felt dissociated, as if body and brain inhabit mutually exclusive worlds.
Della Penna’s first task is to try to bring his clients’ bodies and minds back together—to fire up their body schemas. But he is more often than not astonished by the extent to which his clients are not in touch with their physical bodies. He’ll gently tap a major muscle in the back, arm, or abdomen and ask the client to contract it. They cannot. He puts them in front of a mirror and they won’t look. He asks them to twist at the waist so their shoulders are at a right angle to the mirror. They cannot perform the motion. He asks them to throw their shoulders back by flexing the muscles that pull the scapula together. They have no idea of how to begin. When they try to stand on one leg, they cannot do it. They are completely unable to perform many of the basic skills that so many of us take for granted, he says.
Della Penna focuses on overcoming this body-blindness by getting his clients to experience their bodies from the inside out. He has created a series of proprioception and balance exercises designed to trigger minute neuromuscular responses. After establishing an initial contraction, he builds on the exercise program until his clients are connecting their entire body to the required movement. One method is to have them lift very light weights, very slowly, with many repetitions while pretending they are lifting hundreds of pounds.
“I want them to feel each muscle fiber and each neuromuscular response,” he says. “I tell them that their muscles don’t have a dimmer switch, that we want to trigger all of the neuro-senders and that they need to learn to fire all their muscle fibers while lifting light weights to tone the muscle. Lifting big weights will just make big muscles. I get them to concentrate on their abdominal muscles hundreds of times a day to retrain their bodies to use core muscles in every movement they make. The slower they go, the better they do.”
And then Della Penna brings out the wobble board. His is a homemade affair consisting of an 18-inch-square board mounted on a two-by-two piece of wood, like the blade on an ice skate. You stand on it and try to keep it from wobbling. Your task is simply to maintain your balance the best you can. In terms of body maps, the wobble board provides a powerful entry into body schema repair via stimulation of the vestibular cortex. By putting balance at the center of attention, your body schema cannot be ignored.
When Della Penna’s clients first step onto his wobble board, they have a difficult time keeping it centered. But, he says, “people adapt to it very quickly. After a while, I toss them a ball and have them toss it back. Then I toss two balls simultaneously, which they catch and throw back. As they begin to relax and maintain balance, some get really, really scared. They are getting in touch with their body schema.” Some people become so frightened, they leave the training, he says. Others use the newfound sense to begin to transform their relationship with their body image. It can go either way.
If you have lost weight or toned up, consider ways to broker a truce between your dueling body maps. By getting in touch with your slimmed-down schema, you may be able to keep the pounds off for good.
Waking the Tiger
In 1969, the somatic psychotherapist and stress researcher Peter A. Levine met a woman named Nancy whose experience captures other ways the body can become trapped in past trauma. Nancy, a graduate student, was not battling a weight problem. Her problem was severe, crippling, and, to her mind, completely inexplicable panic attacks.
As Levine recalls in his book Waking the Tiger, he began their session with the standard approach of relaxation training. Nancy sat in a chair, quietly listening, but she did not respond. As Levine pressed on, trying to help her relax, Nancy suddenly imploded, gripped by a full-blown anxiety attack—paralyzed, pallid, unable to breathe, heart pounding.
Levine remembers being drawn into her nightmarish attack. It was palpable, contagious. Then, without warning, he had the fleeting vision of a tiger, crouched, ready to leap toward them. It just appeared in his imagination. Swept along by the experience, he commanded, “Nancy! You are being attacked by a large tiger! See the tiger as it comes toward you! Run toward that tree! Run, Nancy, run! Climb up! Escape!”
To Levine’s astonishment, Nancy’s legs started trembling in running movements. She stayed in her chair, but her legs shook as if in full escape. She let out a primitive scream that brought in a passing police officer. Then Nancy began to tremble, shake, and sob in full-bodied convulsive waves. The shaking went on for an hour and ended with soft trembling.
This event was an epiphany for Levine. Nancy told him that she had, for the first time in her life, recalled a terrifying memory from her childhood. At age three, she had been held down and strapped to an operating table for a tonsillectomy.
Under the anesthesia, which might have been incomplete, Nancy felt she was suffocating. Terrifying hallucinations gripped her mind. The event, etched deeply in her being, was not subject to conscious recall. Like other traumatized people, Nancy felt threatened, overwhelmed, and psychologically stuck. Her body had resigned itself to a state where she could not escape. Hence the panic attacks.
At the time, Levine was studying animal predator-prey behaviors, which may explain the tiger image. He observed that when prey animals are captured—say, an impala is brought down by a cheetah—they drop to the ground and freeze. In the moments before death, prey animals are entirely immobilized and their brains are flooded with natural painkillers. But if they are lucky enough to escape—say, the cheetah does not kill instantly and the impala gets away—the animals will run to safety and then literally shake off the residual effects of the immobility response. Their bodies convulse with paroxysmal spasms.
Looking at Nancy, Levine realized that her shaking was an instinctive and long-overdue response to her being immobilized and terrified as a little girl. He also understood that her panic attacks were not caused by the triggering event itself. Rather, they stemmed from the frozen residue of “energy” that had not been resolved and discharged from her body. After a few more visits and further gentle shaking, Nancy’s panic attacks vanished.
With this insight, Levine, a pioneer in the field of what has come to be called “somatic psychology,” went on to develop a method called Somatic Experiencing. The method helps people access their bound-up energy and release it in a gradual, titrated way by tracking felt sensations in the body. Unlike conventional talk therapy, which can sometimes retraumatize a person, somatic psychology gradually delves into the body state moment by moment. In a way it amounts to turning psychotherapy inside out and upside down. The treatment does not directly address beliefs about the body, or body image. Instead, it focuses on fluctuating internal sensations as embedded in the body schema. If the patient’s posture or body language changes while talking about her past, the therapist makes her aware of it. Or he may ask her to note what visceral sensations she is having while she talks about herself. As her awareness of the connections between her thoughts, memories, emotions, and body states grows, so does her self-possession. In short, somatic psychotherapy uses body sensation as the key to healing trauma. Like the wobble board, it recalibrates your body maps so that you can feel yourself from the inside out.
The Stolen Cat Suit
When the psychologist Martin Grunwald lived in Jena, East Germany, working at Friedrich Schiller University, he kept his experiments simple. Grunwald is interested in the sense of touch—how it is processed in the brain and how it interacts with other senses. So as part of his doctoral dissertation, he blindfolded people and asked them to trace sunken figures with their index fingers. Imagine a triangle or an X or a more complicated squiggle carved into a piece of wood. That is what his sunken figures look like. After the subjects ran their fingers over each shape, they opened their eyes and drew it on a piece of paper.
It’s an extremely easy task, Grunwald says. You simply have to transform what you feel into what you see. You do this all the time without thinking, as when plunging your hand into your car’s glove compartment in search of a hairbrush or sunglasses. A quick slide of the fingertips usually identifies objects immediately.
While the subjects touched the sunken figures or drew them on paper, Grunwald measured the electrical activity in their brains. “I just wanted to observe the kinds of brain signals associated with the understanding of active touch,” he says. Nothing fancy. Just basic curiosity.
With one exception, every person in the experiment drew the shapes accurately, Grunwald says. While their X’s might be a little crooked or their wavy lines a bit off center, they could easily draw what they had touched. The exception was a young woman from Jena University’s psychology department. She was a total, abject failure at the task. Her cramped, tortured drawings bore little or no resemblance to the actual shapes. She seemed incapable of understanding the structure of even the simplest sunken figures.
Grunwald was intrigued. What was with this young lady? As a university student, she was undoubtedly literate and probably quite intelligent. Might she have some odd physical disability that prevented her from being able to feel the sunken figures? Nothing made sense. The mystery deepened when Grunwald tried to set up an interview with the student and she flatly refused to return to the lab. She would have nothing more to do with the experiment, period.
That would have been the end of it, except for an astute observation made by Grunwald’s laboratory assistant. Her notes indicated that the woman’s skin was a very pale gray color and covered with fine soft hairs. And she was extremely thin. Grunwald went to the library and checked the research literature. What kind of illness, he wondered, could produce abnormal touch and such strange skin? He found the answer in a paper on the physical characteristics of women with eating disorders. Her skin was the giveaway. The young woman was profoundly anorexic.
The experts agree that biological and cultural factors are involved in anorexia nervosa, a mental disorder of self-starvation that kills up to 18 percent of its victims. But beyond that, the consensus frays. A leading explanation for the disorder is similar to what people used to say about autism and homosexuality, namely, that it is a learned behavior. In the case of self-starvation, they say, young women do not build a strong identity early in life. That leaves them feeling uncertain, confused, or dissatisfied about who they are. To feel valuable, they fixate on being thin. The oversexed popular culture of billboards and Cosmo covers and taut-midriffed teen pop divas serves to reinforce the fixation. The explanation is entirely cultural and psychological.
But that theory fails to explain one of the most intriguing observations about these sad women who willingly starve themselves to the brink of death. If you give a pair of calipers to an anorexic woman and ask her to estimate the size of her upper arm, she’ll look straight into the mirror and open the pinchers wide enough to encompass Popeye’s biceps. She literally sees her upper arm as grossly fat when it is frightfully thin. Her eyes—or more accurately, her misperceiving brain—tell her what no one else sees.
And she is not making it up.
Such drastic misperception looks suspiciously like a mismatch between body maps. With this clue, neuropsychologists are now starting to investigate anorexia along these new lines.
In 1996, Grunwald moved to the University of Leipzig, where he decided to investigate abnormal touch perception in anorexia patients. Since touch is integrated with vision and other senses in the parietal lobe, he wondered if anorexics have abnormalities in this region of the brain.
When Grunwald repeated his earlier experiment with ten anorexia patients, not one of them could draw the shapes correctly after feeling them. Looking closely at their brains’ electrical activity, he saw that each person’s right parietal cortex was working hard but without success. Sensory information was not being integrated. Could this be why they did not perceive their bodies as appearing skinny in the mirror?
Grunwald believes that anorexia is fundamentally a body pattern disturbance. And he has some ideas as to its source. The disease is seen almost exclusively in women and girls, which points to the effects of sex hormones on the developing brain. It is known that testosterone plays a role in the enhanced spatial abilities of males, which are located in the right parietal lobe. Female brains, by contrast, show subtly different patterns of organization; the right parietal lobe is less specialized for spatial awareness. This trait may be more pronounced in anorexia patients.
Added to this anatomical variation is the fact that early brain development is dependent on human touch—possibly more so in girls than in boys. It could be a genetic trait linked to the female X chromosome. It could have to do with basic sex differences in how emotion develops in the brains of each sex. There are other proposed explanations as well, including insecure attachment. The jury is still very much out. But the final effect, in Grunwald’s view, is unhealthy or incomplete map integration in the right parietal lobe of a disproportionate number of girls. Hence as they grow up, their body schemas are unreliable, while their body images become more and more distorted by social influences.
Anorexia patients hate to be touched, Grunwald says. They do not like physical therapy or massage, and they leave situations in which they are expected to have body contact with others. But what if he could flood their brains with full-body stimulation? Could a powerful input of touch sensation help overcome their distorted body image?
Grunwald, who is thin and gets easily chilled in cold water, had begun using a neoprene diving suit while on holiday with his family. “My daughter is an enthusiastic swimmer and loves to romp and play with me in the waves,” he says. The suit allowed Grunwald to spend many hours with her in the sea water. But in wearing the suit, he noticed distinct bodily perceptions. On land, the suit pressed on his skin and muscles as he moved. In water, he felt less compression. After thinking about these sensations for a few years, Grunwald wondered if a diving suit could help anorexics who have an abnormal response to touch. When he mentioned the idea to a friend, he learned that full-body latex suits are popular among some people for enhancing sexual experience.
And that is how Grunwald got the idea of putting an anorexic patient into a full-body neoprene suit—a cat suit—to see if it would send new, perhaps corrective, signals to her brain.
The patient was a nineteen-year-old artist who agreed to wear the cat suit three times a day, for an hour each time, for fifteen weeks. It fit under her clothes as she went about her normal activities. She liked the idea, Grunwald says. She was relieved that the treatment did not make her talk about her childhood or deal with other psychological issues. Anorexia, in Grunwald’s view, is a disorder rooted in a brain anomaly and not in mommy-daddy issues.
During the experiment, the researchers recorded the artist’s body weight thirty-nine times and assessed the quality of her body representation using several measuring techniques. They also recorded the electrical activity of her brain. Before she wore the suit, when she was starving, her left hemisphere was dominant. After she wore the suit—and had gained several pounds—brain activity shifted to her right hemisphere, particularly to the parietal lobe. She said she loved wearing the suit, Grunwald says, and felt some panic when summer arrived and she had to take it off.
Unfortunately, the effect of the cat suit was not permanent. A few months after the student stopped wearing it, her brain asymmetry returned. She lost weight. Tests showed that she once again failed to represent and evaluate her body realistically. Not long afterward, the woman moved to France and took the cat suit with her, Grunwald says. The suit was expensive and he has asked her to give it back, but she has refused. And for the time being he does not have funding to carry out more tests with other patients.
What Is Wrong with Michael Jackson?
If Grunwald is right, many so-called psychiatric disorders stem from an unhealthy or inadequate representation of body feeling. Anorexia is one. Another is bulimia, which also involves an overestimation of body size. Men suffer from a related condition called reverse anorexia, also known as “bigorexia” or muscle dysmorphia. These are guys who work out obsessively in gyms to the exclusion of a social life. They gaze at themselves in the mirror dozens of times a day, and guess what they report seeing? Instead of recognizing the incredible hulk in front of them, they see someone who looks scrawny and underdeveloped. Could there be a similar brain abnormality causing their perceptual errors?
Men and women with body dysmorphic disorder, or BDD, are painfully focused on the belief that certain parts of their bodies are grotesque. They are tormented by the notion that some piece of them—nose, ears, mouth, jaw, eyebrows, chin, rear end, genitals, you name it—is ugly, abnormal, and deformed. Like having a really bad hair day, they can’t stop thinking about the defect and spend hours secretively looking in the mirror and trying to camouflage it with makeup, hats, wrappings.
Body dysmorphic disorder afflicts one to two percent of American men and women. A quarter of them have had plastic surgery. It can easily spiral to extremes. Think Michael Jackson.
Like anorexics, when people with body dysmorphic disorder look in a mirror, they literally see the exaggerated defect. Their rear end is disproportionately huge. Their chin is completely missing. They have gorilla-like hair on their faces. Their hands and fingers blow up in size, then shrink, before their eyes. Again, they are not making this up. They truly see themselves this way.
Neuroscientists recently discovered an area of the brain, with connections to the parietal region, where body parts—legs, hands, arms, trunks without heads—are visually recognized. Could defects of this region of the brain (the extrastriate body area) be involved in body dysmorphic disorder? There are, in addition, other visually dominant body maps in the parietal lobe itself. The mind uses these maps to recognize its own body and tell its own body parts and movements apart from those of others.
But in anorexics, bulimics, even in many normal dieters, and perhaps in those with body dysmorphic disorder as well, somehow top-down beliefs and expectations (from the body image) cannot get in harmony with the bottom-up flow of unbiased sensory information from the body and eyes. The parietal lobe, with its gaggle of visual body maps, may be the bottleneck where the communication is breaking down. But while the clues are tantalizing, neuroscience research on the question has just begun.