World's greatest free-solo climber, Alex Honnold, doesn't experience fear like most people do.
Honnold is known for his various feats of scaling natural terrains bare-handed and without any safety measures. His latest achievement----climbing the El Capitán rock formation at Yosemite National Park in roughly 4 hours----is considered a landmark in El Cap's long history of mountain climbers. (1)
Recently, researchers at Medical University of South Carolina, in Charleston requested Honnold to enter a fMRI scan in order to understand how he manages to perform such superhuman feats. The experiment also compared Honnold to a control subject: another free-solo climber who has normal responses to stimulating images. While inside the active MRI's bore, both Honnold and the control subject were shown a series of "disturbing" and "exciting" images such as "corpses with their facial features bloodily reorganized", "invigorating mountain-climbing scenes", and "gruesome burning children". (2) The MRI scan revealed an intact, and even healthy amygdala from Honnold. However, there was virtually no brain activity even as he was shown the images.
Now the question comes down to why Honnold's brain reacted the way it did. His tests results indicate he is a high-sensation seeker, perhaps to compensate for the higher stimulus threshold set by his particularly inactive amygdala.
There are many theories as to whether if Honnold's high tolerance for fear stimuli is genetic or a result of his upbringing. Without going back in time to measure his amygdala activity before he embarked on his free-soloing career, there is no way of knowing how the climbs affected Honnold. However, researchers have hypothesized that habituating to highly-stimulating environments may elevated the threshold for triggering Honnold's amygdala.(3)
Besides becoming acquainted with the dizzying sight of hanging between life and death, Honnold also exhibits high levels of concentration and is a careful planner: he would rehearse his routes up towards the summit, practice moves to ensure peak performance, to name a few precautions. The reconsolidation of memories related to free-soloing may have helped him become a better climber in the process as well as dampened his fear.
Researchers are further looking into how Honnold managed to suppress and overcome his fear as an athlete. The results may provide insight to curing aggression, anxiety, or better understanding risky behaviors such as drug abuse. It may also help others conquer their fear through similar methods as "honnolding".