The Science of your Mind in Danger
By Jeff Wise
Palgrave Macmillan Copyright © 2009 Jeff Wise
All rights reserved.
THE PERSON THAT FEAR MAKES YOU
THE PLANE IS at twelve thousand feet when the door slides open, and all at once the cabin is filled with a chill and the sound of roaring wind. Outside, the clear blue light of an autumn afternoon bathes the North and South Forks of Long Island. Without pausing, a man in a red jumpsuit crawls to the edge of the doorway and tumbles out, followed by a woman in yellow, then another man in blue. The tail of the plane bumps upward each time a jumper's weight leaves the sill of the door.
Now my instructor and I are alone here in the bare, seatless cabin. "Okay," he says. "Let's scoot forward."
I think: Ugh.
He starts to scramble forward, crab-like, and I have no choice but to follow suit, because we're strapped tightly together, his chest to my back, his pelvis against mine. I feel numb. My chest feels tight, my mouth is dry. I wish I were anyplace but here. My mind is racing as I try to keep control. I think of that hoary cliché of skydiving, the petrified first-timer clinging white-knuckled to the edge of the door. Am I going to be like that? Am I going to lose it? Or am I going to keep it together?
I feel weak, barely able to move my own weight. As we reach the door, a whole uninterrupted panorama of Long Island opens up before me, the forests dappled with the oranges and reds of early autumn. To the south, the arc of the Atlantic Ocean merges into the paler blue of the sky. Everything looks so crisp, so crystalline, with a beauty that would be stunning if I had the least interest in looking at it. The wind howls past as we put our feet over the edge. There's nothing below us but air, thousands and thousands of feet of empty air.
I think: What the hell am I doing here?
Actually, the answer is very simple. I've volunteered to take part in an experiment in the nature of fear. It's a decision that, at the moment, I'm regretting deeply.
Duncan makes one final check of the equipment. The electronic recorder strapped to my waist is on and collecting data from the sensor vest around my torso. Duncan's voice comes from behind me, the words that he'd explained on the ground would be our final signal to push away from the airplane: "Head back—ready—set—arch!"
GOING UP IN a skydiving plane for the first time taught me the lesson all over again: In the grip of fear, our minds work differently. Our bodies and brains simply don't respond the way we expect them to. Tasks that are very simple when undertaken in a state of calm become intensely challenging, or even impossible, when the adrenaline is pumping. Conversely, we might rise to the occasion and perform much better than we would have any reason to suspect. It's impossible to know beforehand which way we'll break.
The question of who will rally in the face of danger, and who will crumble, is an imponderable that has fascinated people since time immemorial. Some who talk tough turn into cowards in the face of battle; others who seem meek prove fearless. As the eighteenth-century French aristocrat François de La Rochefoucauld put it: "One cannot answer for his courage when he has never been in danger."
Twentieth-century psychologists, eager to figure out how to extract maximum usefulness out of service personnel like soldiers and firemen, attacked the problem with renewed vigor. During World War II, the Air Force tried to use the new science of psychometrics to determine who would "endure the stresses of flying and combat," but had no luck, ultimately concluding that "the only valid test for endurance of combat is combat itself." In the 1980s, Canadian psychologist Stanley Rachman tried again, conducting a study of British Army bomb disposal experts. Despite running numerous tests on these men, he found it impossible to correlate their psychological profiles with their performance under pressure. It had begun to seem as though the mystery might remain unsolved.
In the last decade, though, technology has tilted the game in scientists' favor. Functional magnetic resonance imaging (fMRI) brain-scanning machines allow neuroscientists to peer directly into the activity of the living brain. These machines use strong magnetic fields to induce changes in the orientation of hydrogen atoms, which then respond differently to pulses of electromagnetic radiation depending on the chemical environment. Since active regions of the brain use more oxygen, an fMRI scanner can pinpoint which areas are busiest at a given moment with a lag of just a few seconds. These areas of activation are correlated with anatomical understanding generated through past research, such as brain-lesion studies, which have already provided a rough atlas of what functions are carried out where. With fMRI, then, researchers can see how different functional areas of the brain work together, without any danger or discomfort to the test subject.
Dr. Lilliane R. Mujica-Parodi thinks she can use fMRI technology to crack the mystery of fear. As director of the Laboratory for the Study of Emotion and Cognition at the State University of New York at Stony Brook, on Long Island, she wants to find out if there's a way to test someone in a normal setting that will identify how they will behave in a perilous one. She wants, in other words, to overturn Rochefoucauld's dictum.
What struck me about Mujica-Parodi's work, when I first came across it, was the unusual lengths to which she goes in order to elicit a vigorous fear response. For the last few years, Mujica-Parodi and her team have been examining human test subjects not only in the laboratory but also in the field. First, her subjects are hospitalized for several days, during which time they're asked to run on a treadmill and to provide blood, saliva, and urine samples. Then they're exposed to mild stressors—for instance, they're shown pictures of emotionally upsetting crime scenes. Finally, their brains are scanned in an fMRI machine.
So far, none of this is particularly extraordinary. Neuroscientists have been performing this kind of experiment for years. "Researchers have already shown that it's possible to predict with some efficacy, based on fMRI experiments, how people behave in response to a mild laboratory-induced stressor," Mujica-Parodi told me, when I called her on the phone to ask her about her work. "What we want to do is take it one step further and see if these measures that we see in the fMRI are actually predictive of a real-world stressor."
By "real-world stressor," what she meant was an experience that's intensely, grippingly frightening. For researchers, finding a way to explore how such a thing affects real people poses something of a challenge, as it's considered unethical to put people in actual mortal danger for the sake of psychological research. So Mujica-Parodi has come up with the next best thing. She recruits people who, of their own free will, have decided to go for their first-ever parachute jump at Skydive Long Island, a small operation about twenty miles east of the university. She does this by putting up a sign on the wall inside the jump center's office next to the airfield. The sign explains what she's doing and offers a small fee for volunteers. Anyone who takes her up on her offer is fair game, by ethics-review-board standards, for extreme fear research. And so Mujica-Parodi can run them through her tests, and compare their response to mild, laboratory-induced stressors with their physiological reaction to the sheer terror of freefall from twelve thousand feet.
As she told me this over the phone, I realized that I had stumbled on a rare opportunity: There couldn't be a better way to learn about cutting-edge fear research than to actually take part.
A FEW WEEKS LATER, I check myself into the research wing of Stony Brook Hospital for the first of the two-part experiment—the low stress-level part. I'll be at the hospital for two days, eating hospital food and sleeping on an adjustable hospital bed equipped with automatically inflating pouches in the mattress, the kind designed to prevent bedsores. It's important for me to stay in a controlled environment, Mujica-Parodi explains, so that her team can get an accurate measure of my body's baseline—a sense of what my hormones, heart rate, and other measures of stress are like when I'm in resting mode. I wear electrodes that measure my heart rate, and periodically the staff collects blood and saliva samples.
On the final morning, I lie down on a sliding table and am rolled inside an fMRI scanner, a donut-shaped machine that throbs and hums as its magnetic fields invisibly probe my brain. I remain motionless for forty-five minutes, staring up at a screen that displays pictures of different faces. Some are angry, others laughing, others wear blank or neutral expressions. It's my response to these latter faces that Mujica-Parodi is most interested in.
As I lie there looking at these faces, I'm not aware that I'm feeling any emotion one way or another. They're just pictures of faces. But deep inside my three pounds of gray matter, my fear centers are doing their thing. While I'm lying in the scanner, Mujica-Parodi is sitting inside a nearby control booth with a technician, looking at a cross-section of my brain on a computer monitor.
Later, she shows me some of the images. The most highly activated regions are lit up in red, orange, and yellow. The first region she points out is the thalamus, located in the middle of my head, at the top of my brain stem. A pair of bulb-shaped lobes, the thalamus operates as a kind of routing center in the brain's information superhighway, taking sensory data from the eyes and ears and body and shunting it off to the various parts of the brain. When I looked at the pictures of the faces, the light entered my eye, triggering neurons to fire in my retina, which sent a flow of information through the optic nerve to the thalamus. There the data stream split in two. What happened in the course of these two pathways lay at the heart of the mystery of fear.
The first route led to the amygdala, a pair of almond-shaped nerve centers located just in front of the thalamus and on either side. The second route headed to the neocortex, the deeply grooved and wrinkled tissue that lies on the surface of the brain. Specifically, it wound up at an area that lies just below the forehead, the frontal cortex.
I tell her that this is a region that I'm already familiar with. The frontal cortex is the part of the brain associated with the higher mental functions. It's a newcomer, in evolutionary terms. The main difference between human beings and closely related animals like chimpanzees and gorillas is that, in the last few million years, our frontal cortex has grown significantly bigger. It's not too much of an oversimplification to say that many of the higher faculties that we think of as uniquely human—our ability to reason and to plan ahead—are centered in the frontal cortex.
The amygdala, though, is less familiar to me. Mujica-Parodi explains that it's part of a much older region of a brain called the limbic system, which lies deep below the neocortex and handles many of the brain's more primitive processes, including emotion and memory. In particular, the amygdala is the key center for evaluating threat. As the visual information flows in from the thalamus, the amygdala scans it for any signs of danger.
The amygdala is also responsible for learning emotional associations. If I'm walking along the street and a dog bites my leg, I'll not only form a conscious memory of the event, but my amygdala will form a separate, subconscious one. Since I have no awareness of what memories are stored by the amygdala, if I don't have a conscious memory of an event, I might later find myself having an emotional reaction to something and not understanding why. For example, as infants, we're able to form long-term emotional memories long before we can form conscious ones. Leading fear researcher Joseph LeDoux of New York University has proposed that some phobias might arise when a person experiences something traumatic as a young child—a bee sting, say—that remains potent in the amygdala and thus able to inspire fear even without a conscious awareness of the cause.
When the amygdala identifies something in the environment as a potential threat, it triggers a series of alarms that result in all the outward signs of fear: trembling, sweating, blanching, and so forth. It also activates the insula, a region midway between the limbic system and the neocortex that's responsible for the conscious sensation of fear.
The amygdala sends numerous projections to the frontal cortex, and vice versa. From Mujica-Parodi's perspective, it's the nature of the dynamic between these two regions that's essential in understanding how a person responds to stress. If the amygdala detects a potential threat but the frontal cortex analyzes the data in more detail and determines that no threat is present, the cortex will tell the amygdala to quiet down.
Mujica-Parodi chooses a scan of my brain that was taken while I was looking at a neutral face, and points to a subregion of the frontal cortex called the ventromedial prefrontal cortex, or vmPFC. "The amygdala always responds to novelty," she explains. "When I show you a neutral face, the amygdala says: 'Oops, what's that: Is it dangerous?' And then the inhibitory component"—the frontal cortex—"kicks in and says, 'You know what, it's not. Calm down.'"
Because the faces I looked at weren't scary, my frontal cortex shut down the amygdala's response before I could become aware of it. The entire response was taking place automatically, outside of my consciousness. As far as I knew, nothing was happening at all. I was simply remaining calm. But while all this was going on, Mujica-Parodi was measuring the interactions between the two and testing the dynamic between the amygdala and the frontal cortex. From her analysis, she believes that she can predict how a person—me, in this case—will respond when they're well and truly terrified.
Now, to test this hypothesis, we have to move on to phase two. Real terror.
ON A CRISP CLEAR MORNING in early October I wake up before dawn in a motel room in eastern Long Island; shower, pack up my bags, and check out. I've slept poorly, troubled by uneasy thoughts that kept my mind skittering over the surface of sleep. As I drive along the Long Island Expressway I not only feel tired but also vaguely ill.
I drive past the abandoned Northrop Grumman factory where the F-14s featured in Top Gun once were built. It's just then, as I make a left-hand turn, that my anxiety spikes, and I wonder if I am going to make it through the morning. An awful sense of helplessness sweeps over me. I feel woozy and short of breath, but I decide to drive on, and tell myself that if I feel substantially worse, I'll stop. That idea calms me down a bit, and soon I'm at the edge of the airfield, where a small white building houses the office of Skydive Long Island.
To get the full measure of a test subject's response, Mujica-Parodi's assistants conduct a battery of tests before, during, and after each skydiving session. As soon as I arrive, two graduate students in white lab coats usher me inside a trailer, where a burly phlebotomist extracts several vials of blood. I also give urine and saliva samples. Next, I strip down to my waist so that the research assistants can fasten electrodes to my chest. Then they help me into a special vest that will measure my lung volume. A satchel contains an altimeter to show when my jump starts and a digital recorder to carry all the data. Over that I don my shirt, a fleece, and a flight suit.
Then I'm led into another room in which I watch a mandatory video explaining the basics of tandem skydiving. It reiterates forcefully several times that, due to the multiply redundant waiver I've just signed, there's absolutely no way my heirs will be able to sue Skydive Long Island, regardless of the circumstances.
As I watch I feel acutely conscious of the gear strapped to my body. It's intended to monitor, I know, not the activity of my brain directly, but rather the effects of one particular subsystem, the autonomic nervous system (ANS), which is responsible for producing the symptoms of arousal in the body.
In evolutionary terms, the ANS is an ancient structure, even older than the amygdala. It dates back to a time when our ancestors were no more than primitive fish swimming in the Paleozoic sea. Back in those long-ago times, our ancestors' main concerns were fairly simple: eating, reproducing, and not being eaten. Evolution had furnished them with a nervous system that was commensurately simple; really nothing more than a network of neurons stretched out along the spinal column. Today, that's what our ANS still looks like: a ladder of knot- like nerve centers, or ganglia, stretching along the spine.
This system is divided into two opposing and complementary parts, the parasympathetic and the sympathetic nervous systems. When conditions are benign, the parasympathetic nervous system, PNS, comes to the fore, sending out impulses from the ganglia to organs throughout the body, encouraging them to do the sorts of things that one does when it's summertime and the living is easy. We relax. The heart rate slows down. Glands release saliva in the mouth and bile in the gut to assist in digestion. In the right context, the PNS helps generate an erection. (Continues...)
Excerpted from Extreme Fear by Jeff Wise. Copyright © 2009 Jeff Wise. Excerpted by permission of Palgrave Macmillan.
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