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Stress Test
The Science of Fear
Tim Bauer
October 2008
Can a person's behavior in the face of danger be predicted? What will prevail—courage or cowardice? The attempt to answer this eternal question gave birth to an entire discipline: the science of stress.
Nerves extending from the brain and spinal cord are classified, depending on their functions, as either the somatic ("bodily") nervous system, which coordinates skeletal muscle reactions, or the autonomic ("vegetative") system, consisting of two functional divisions: the sympathetic and parasympathetic. They provide involuntary regulation of all body organs, occurring without conscious participation.
My God! I would give anything just to be anywhere else right now. A cool, clear morning at a remote little airfield on the eastern end of Long Island. Against a piercingly blue sky, bright green trees growing along the runway stand out sharply. Duncan Shaw, an instructor at the parachute school, hands me a jumpsuit, gloves, and a leather helmet. In a few more minutes, a Cessna 207 will carry us to an altitude of four kilometers, and then... then I'll have to jump out of it. A beautiful day is beginning, and I realize that in purely rational terms, I have nothing to fear. And yet, I am filled with an all-encompassing sense of terror.
Shaw repeats the actions I must perform during the jump one last time, and we climb into the plane. The aircraft climbs steeply; I try to focus on my own breathing, but instead, I experience the full standard set of symptoms characteristic of fear syndrome: my heart pounds uncontrollably, my mouth is dry, the contents of my stomach want to come out... But then the plane levels off, and the door in front of me is slid aside, leaving only a roaring void. The ground is somewhere below, terribly far away. A stereotypically comical image of a novice parachutist flashes before my eyes—frozen with fear, clinging to the doorframe with whitened hands using every last bit of strength. Will the same thing happen to me?
I have more than just a personal interest in this question—after all, I am participating in experimental research on how people react to acute mental stress. The experiments are conducted by Liliana Mujica-Parodi, director of the Laboratory for the Study of Emotions and Cognitive Abilities at Stony Brook University. And so here I stand in the hatch opening, wrapped in wires extending from various sensors, with a chance in the coming minutes to become either another point on experimental diagrams or a large red blotch on the bright green airfield grass.
A few weeks before this jump, I had already visited the research wing of Stony Brook University Hospital. First, I had to undergo a two-day examination so that Liliana could get a general idea of the threshold levels characterizing my psychological excitability. She is particularly interested in areas of the temporal lobes of the brain called "amygdalae," or simply amygdala (Lat. amygdala). It is this element in the overall system of nervous activity that controls the fear response. The researcher believes that if she can understand how the amygdala functions, she will be able to revolutionize the study of stress—by examining a person in advance, in laboratory silence, she could predict their behavior in extraordinary conditions. Such capabilities are of particular interest to the military—which is why this research is funded by the Department of the Navy. In any case, such knowledge is useful whenever personnel must be recruited for activities involving regular dangers.
At the hospital, I was entwined with wires from sensors monitoring my heart; periodically, blood and saliva samples were taken for analysis. The next morning, I underwent a functional magnetic resonance imaging (fMRI) procedure, during which, lying inside the scanner, I stared up for 45 minutes at a monitor showing images of various faces. Some expressed nothing; others looked quite angry. In my conscious mind, I didn't track any particular emotions—faces were just faces. But then there is the electrical activity of my brain—which is exactly what interested Liliana—specifically, the interaction between the irrational, easily excited amygdala and the prefrontal cortex of the cerebral own, which generates conscious thoughts and intentional actions. "The brain acts as a kind of negative feedback control system, similar to a thermostat in your home's heating system," the researcher says. "When I show you a face without a specific expression, the amygdala asks: is there danger hidden here? Then a prudent participant (the cerebral cortex) joins the conversation and demands that everyone calm down because no one is threatening anyone. However, if there is a real threat, the cortex will undoubtedly support the fearful reaction of the amygdala."
Liliana believes that the question of who can better withstand an acute sense of danger is largely determined by how this feedback is utilized. In a home heating system with tight regulations, the heat turns on as soon as the temperature in the house drops slightly. The furnace brings the temperature back to normal and then returns to standby mode. But if the feedback slack is too great, everyone in the house will have frozen through before the heating finally kicks in. After that, the furnace makes up for lost time and, before turning off, makes everyone sweat.
Based on the results of the tomogram, Liliana concluded that negative feedback in my brain works quite clearly. The "furnace" in the amygdala flares up quickly when needed but continues to heat no longer than necessary. If this interpretation is correct, I should exhibit sufficient composure in frightening situations. In simple terms, I should act as a brave man. However, until it came time for the actual parachute jump, all these arguments sounded not very convincing.
And so we are back in the cabin of the Cessna. I am tightly strapped to the instructor's chest; we are on the threshold of the hatch, and the wind howls past. I stick my head directly into this resilient same airflow; the cold wind flattens, presses, and pulls at my cheeks. Below us there is nothing but air, and no amount of psychological theorizing can push away the terror that has seized me. Scientifically speaking, nothing can help the brain curb the raging amygdala.
From behind, I hear the instructor's voice: "Tuck your legs... Tilt your head back... Ready... Go!" We pushed off from the fuselage and are tumbling, falling through the air. My consciousness is overloaded with emotions, so I am unable to process them. Out of the corner of my eye, I notice a little plane somewhere in the distance. A few more seconds, and we reach terminal velocity. Our bodies stop tumbling, freezing in a horizontal position. The view—for many kilometers in all directions. Beautiful!
Five more minutes, and I am standing firmly on the ground. I enter the laboratory set up right on the airfield and take off my jumpsuit. Two lab assistants in all white peel electrodes from my bare torso. A stout male nurse enters the laboratory with a pack of sharp needles—they are about to draw my blood. I have no complaints. To be honest, I am simply obsessed with euphoria. How wonderful it is to be alive!
A bit later, Liliana will email me a couple of diagrams and graphs and explain what they mean. As it turned out, one graph shows the heart rate before, during, and after the jump, while the accompanying diagram records so-called "sympathetic dominance."
There are obvious symptoms of stress reaction—trembling, dry mouth, rapid breathing, and heartbeat. This involuntary reaction is set by those circuits in our brain that choose between panic flight and confronting danger, and these circuits, in turn, act in direct dependence on the feedback loop between the amygdala and the prefrontal zone of the cortex. The clarity of this connection can be characterized by a parameter called "sympathetic dominance." When I was examined in a calm, safe environment in the hospital laboratory and hadn't even thought about parachute jumps, this parameter was 4.9—roughly the same value as all other experiment participants. More interesting is that when the plane was gaining altitude and I was preparing for the jump, this parameter rose to five (which is significantly lower than the average value for such a situation—it should be approximately 6.5). In the moments I spent in free fall, it jumped sharply to 13.4, meaning it more than doubled the average indicators. And finally, when I was back on the ground, in just 15 minutes, it fell from a maximum of 13.4 to a respectable indicator of 8.4.
"This indicates that you have good selectivity in your reaction to threat," Liliana explains. "Your psyche has rubber-like elasticity; it yields to excitation but then easily returns to normal, and the 'sympathetic dominance' parameter comes into play only when there is a real need for it."
These graphs mirror the results of the preliminary tomographic examination. It cannot be said that I maintained complete composure while plummeting toward the ground. "The danger was quite real," the researcher explains, "so strong excitation can be considered an adequate reaction." But then, when the fall ended, my brain easily suppressed the panic and stopped the waste of energy. The result—I am capable of maintaining composure in the face of mortal danger, so I'm well-suited to be a firefighter or police officer. But here is the most important thing—the experiments conducted on me seem to confirm Mujica-Parodi's hypothesis, which means that in the future, when selecting personnel for military and law enforcement service, certain methodologies could be used to prescribe the most suitable training programs and job responsibilities for candidates.
Our conversation returned to discussing the parachute jump. "Well, will you jump again?" Liliana asked. "Perhaps, yes," I answered. Of course, but not right now. Maybe in a month or two. For now, I am incredibly glad that my amygdala has gone back into hibernation.
Taken from Popular Mechanics magazine.
Freud
