by Sam Kean
18. adult brain cannot grow new neurons: One of the most radioactively controversial topics in neuroscience in the past few decades has been whether the adult brain can in fact grow new neurons, a process called neurogenesis. Neuroscientists would once have said no, never. Today, most accept that new neurons can appear in two places: in the olfactory bulb, which processes smell, and in part of the hippocampus, which is crucial for forming memories. As for whether new neurons grow in other places, there’s no consensus, to say the least.
19. is a disaster: Michael Finkel wrote a fantastic profile of Kish in the March 2011 issue of Men’s Journal. My favorite moment was when Kish made fun of Finkel’s parking job, chiding Finkel for leaving his car too far from the curb. A moment later Kish popped out his prosthetic eyeballs. The article also explains that, while echolocation can revolutionize the lives of some blind people, only 10 percent ever master it.
Chapter Four: Facing Brain Damage
20. provided a cover flap: Medieval and Renaissance surgeons sometimes transplanted skin from one man onto another, as an early sort of plastic surgery. But many people avoided this procedure because they believed that if the donor died before the recipient, the donor’s transplanted skin flap would also die. On the other hand, those who received transplanted skin could supposedly communicate telepathically with the donor, so there was that.
The “arm flap” method used to grow new skin, from the patient’s own body, onto the nose. An early form of rhinoplasty from the 1500s.
21. Francis Bacon portrait: Francis Bacon would tear out pictures of men with diseased gums and other deformities from old textbooks and use them as models for his macabre portraits, including the “screaming popes.” Similarly, the designers of the blockbuster video game BioShock (released in 2007) dug up pictures of men with destroyed faces from a WWI plastic surgery archive and used them to create a race of mutants.
22. into the left hemisphere: Note the careful wording here. It’s not true that everything that your left eye sees ends up in the right brain. Instead, your right brain deals with everything in the left visual field—that is, everything that the left half of your left eye and the left half of your right eye see. Similarly, everything in the right visual field—everything that the right half of your right eye and the right half of your left eye see—ends up in the left brain. In other words, some visual data crosses over. (Some, but not all: because the nose gets in the way, there are slivers of sight to the far right and far left that enter only one half of the brain, a point that will become important in chapter 11, when we encounter “split-brain” patients.) Anatomically, both eyes can send information to both sides of the brain because the optic nerves that lead out of the eyes split at a point called the optic chiasm, directly beneath the brain, and certain nerve fibers cross over.
23. the whole visual field: A quick note on the geometry of the primary visual cortex. I’ve been throwing around the word “column” because neuroscientists do, but don’t take that too literally. Cells in the cortex don’t form perfect stacks, like little Greek pillars. And things get even messier on a macro scale. Hypercolumns function somewhat like the compound eyes of insects, but hypercolumns don’t look like insect eyes at all. That is, they lack the beautiful crystalline regularity of insect eyes, and they don’t have regular, well-defined boundaries, either. Instead, hypercolumns look like parallel slabs of bread in some places, pinwheels in other places—and the primary visual cortex overall looks like the whorls and loops of fingerprints, with no real order or larger pattern. “Columns” and “insect eyes” are useful metaphors, but they’re only metaphors.
24. a Corvette: Following this logic further, you might expect neurons in the what stream to get more and more specific in what they respond to at each step—until you eventually reach one single neuron that lights up, lightbulb-style, only for a certain Corvette-with-dice-in-the-mirror-and-inappropriate-bumper-sticker-that-your-creepy-neighbor-owns. Some neuroscientists did once believe in this step-by-step convergence to a single neuron, which they called a “grandmother cell,” since you’d have to have one dedicated just to her. But the idea now stands in low repute. Again, instead of a single neuron flickering on, the brain almost certainly looks for patterns of neurons that flicker on en masse. You don’t have grandmother cells, but probably do have “grandmother ensembles.”
25. important note: If you forget everything else in this book—the title, my name, all the sex and violence—please, please remember this: nothing in the brain is strictly localized. Everything your brain does depends on many different parts working together—there’s no “language spot,” no “memory spot,” no “fear spot,” no (heaven help us) “God spot.”
Now, it’s true that some parts of the brain do play a bigger role in language or whatever than other parts. And people do sometimes, as a shorthand, refer to a spot “for” some faculty. (I do it, too!) But talking about one specific spot like that is a deliberate oversimplification.
And be hyperskeptical of news stories that purport to show, with candy-colored brain scans, an anatomical island that “explains” some complicated attribute of the human mind. It ain’t never so simple. Some neuroscientists have criticized the worst brain-scan studies as “brain porn,” “brain voodoo,” and “the new phrenology.”
26. the hang of humans again: This story about the shepherd brings up an interesting question: if this man could recognize individual sheep by looks, could the sheep recognize him? Probably not. Sheep seem to lack the cognitive circuitry. But at least one animal, the crow, can tell human faces apart. Science reporter and radio host extraordinaire Robert Krulwich once did a story about a biologist who harassed crows in the course of his research—to the point that the crows would dive-bomb him (and only him) whenever he passed by. The biologist wondered how they picked him out, and he concluded through a series of experiments that they could recognize his face.
First, he donned a caveman mask and harassed a murder of crows until they learned to hate the masked figure. He then transferred the mask to people of all different shapes, sizes, and gaits—old people, children, limpers, bald people. The crows promptly transferred their loathing to the person with the mask. The kicker was that when he put the mask on upside down, the crows would swoop by upside down to get a look at him. You can hear the story at http://www.npr.org/blogs/krulwich/2009/07/27/106826971/the-crow-paradox.
27. hand gestures in prelanguage communication: Funnily enough, the neuroscientist who discovered hand-loving neurons, Charles Gross, discovered them in a way quite similar to Hubel and Wiesel’s discovery of line-loving neurons. It was 1969, and Gross had wasted hours one night trying to get certain neurons inside a spider-monkey’s visual cortex to respond to something—anything. Desperate, he waved his hand in front of a projection screen near the monkey’s eyes, as if to say, Pay attention, damn it. The neuron did: rat-a-tat-tat-tat-tat-tat. Gross spent the next twelve hours playing shadow puppets and cutting out shapes and holding them up to determine which outlines the neuron liked best. The answer? Slender monkey hands, natch—hands with longer and slimmer fingers than human hands.
While we’re speaking of Gross, I highly recommend his books A Hole in the Head and Brain, Vision, Memory.
28. “Mr. Potato-Head without the features”: The quotes here and below, as well as many more details about Dallas Wiens, can be found in Raffi Khatchadourian’s excellent story in the February 13, 2012, New Yorker.
Chapter Five: The Brain’s Motor
29. the pineal gland: In truth, the pineal gland—a remnant of a third eye that vertebrates used to have (really)—helps detect light and influences our sleep/wake cycle. And yes, because I know you were thinking it, the name of the pineal gland does seem to derive from another body part, since a few early anatomists insisted that it looked just like a penis. That’s far from the only neurostructure that had a ribald name way back when. Gutter-minded anatomists also named various brain bits after the buttocks, testicles, vulva, and anus.
30. ringed every hospital: In these days before antiseptics, doctors themselves also suffered high mortality rates. Florence Nightingale, a nurse during the Crimean War (1853–1856), watched one particularly inept surgeon cut both himself and, somehow, a bystander while blundering about during an amputation. Both men contracted an infection and died, as did the patient. Nightingale commented that it was the only surgery she’d ever seen with 300 percent mortality.
31. tied up with phantoms: No one knows whether the rise in male-to-female sex-change operations in the past few decades has led to a corresponding rise in the number of cases of phantom penis, but perhaps not. Scientists who study phantoms have noted that most male-to-female transsexuals never felt their genitals belonged to them anyway—possibly because their hardwired, internal body scaffolds were anatomically female. If that’s true, phantoms wouldn’t appear. Along these same lines, just as people born without arms or legs can feel phantom limbs, these scientists predict that female-to-male transsexuals should feel phantom penises from an early age.
32. greater pleasure: Neuroscientist V. S. Ramachandran has suggested that one common sexual fetish, a foot fetish, might result from cross-wiring between the brain map’s foot areas and genital areas. He admits he’s speculating here, but argues that this idea is at least as plausible as Freud’s explanation—that to our nearsighted subconscious, the foot resembles a penis. By the way, Ramachandran is one of the most brilliant and creative neuroscientists out there, and I highly recommend his books The Tell-Tale Brain and Phantoms in the Brain.
33. take phantom limbs seriously: Just to be clear, Mitchell did not believe in spiritualism and intended the ending of “The Case of George Dedlow” to be a farce. He loved exposing mediums as frauds, in fact, and was bemused when spiritualists seized upon the story as “proof” that séances worked. Also, it’s not clear why people clamored to visit Dedlow in Stump Hospital, since the story clearly (albeit briefly) states that he got transferred to another hospital later.
And in case you’re wondering, the U.S. Army Medical Museum (now the National Museum of Health and Medicine) does have two specimens numbered 3486 and 3487, but they’re not legs. The first is a cranium fragment from an Illinois private wounded near Atlanta; the second is a left humeral fragment from a Michigan private also wounded near Atlanta. The latter survived.
Chapter Six: The Laughing Disease
34. mini-brain all by itself: Odd fact: the cerebellum contains something like three-quarters of all the neurons in the brain. There are two possible ways to interpret this. One, despite what we might think—that movement is a “low-level” brain function, and cognition a “high-level” brain function—movement actually requires plenty of sophisticated brainware. Two, perhaps the cerebellum plays a bigger role in cognition than scientists traditionally give it credit for.
35. barbaric “bushman” stereotypes: Gajdusek always felt protective of the Fore. Besides defending them against “bushman” stereotypes, he seethed when an Australian tabloid dubbed kuru “the laughing disease,” which he found derogatory and flip. On the other hand, when Gajdusek wanted to shock people, he was not above indulging in stereotypes himself. In a letter to his mother he once bragged, “[My hosts] were still spearing each other as of a few days ago.”
36. dead neurons and spongy holes: No one knows whether prions kill neurons directly or indirectly. Perhaps the buildup of prion plaques simply creates a toxic by-product, or disrupts some key process in a roundabout way. But it’s clear that there’s a strong correlation between prion plaques and neuron damage. One complicating factor is that scientists still don’t know what the normal, healthy prion protein does. Different experiments have linked it to the production of myelin sheaths, the birth of new brain cells, the plastic rewiring of circuits (especially in young brains), and the transport of copper ions. And while it’s especially active in brain cells, all cells seem to manufacture it.
By the by, Kurt Vonnegut fans might have noticed an analogy between prions and the “ice-nine” of Cat’s Cradle, a special form of ice that turns solid at room temperature and that creates more of itself by latching onto and corrupting other water molecules. Prusiner had read the book and enjoyed drawing the comparison.
37. in subsequent interviews: Those who knew and loved Gajdusek continue to debate his guilt or innocence. Many details of his life look like classic signs of pedophilia, not least his decision to go into pediatrics. On the other hand, he supposedly pled guilty to the molestation charges only to avoid a lengthy trial that would have bankrupted him. Friends also alleged that the FBI promised to support the first accuser financially if he accused Gajdusek—which doesn’t invalidate his testimony but does make it more suspect. That the allegations emerged in the 1990s—when the U.S. went hysterical over child abuse—raises suspicions as well. And lord knows that cops have railroaded people into false confessions before.
That said, at least four allegations of sexual abuse and inappropriate touching emerged against Gajdusek before the FBI got involved; all were dismissed for lack of evidence, but the pattern looks disturbing. Plus, in the heartbreaking BBC documentary The Genius and the Boys, Gajdusek claimed on camera to have had sexual contact with hundreds of boys across the world. That’s probably an exaggeration: Gajdusek loved provoking people and mugging for the camera. (At one point in the movie he also speaks out in favor of “intergenerational” incest, and says that children should enter their parents’ bedrooms at night and assist with sex.) But the documentary claims that at least seven men have now accused Gajdusek of having sexual contact with them as boys, and one, an American, does so on camera in the film.
Chapter Seven: Sex and Punishment
38. a morphine addict: Society had a higher tolerance for addicts back then, especially among gentleman professionals. The morphine junkie, William Halsted, also had a taste for cocaine. And William Sharpe told a disturbing story about seeing one eminent surgeon gulp a slug of whiskey right before an operation. Five minutes later the surgeon tried to punch a hole in the back of a patient’s skull to access the brain, but he pushed too hard, puncturing the brainstem and killing the patient instantly. He muttered to a few visiting doctors, “It seems that the operation is over,” then slunk off. Sharpe found him in the doctors’ changing room drinking more whiskey, his hands shaking.
39. hands, feet, and facial bones thicken: Synthetic growth hormone makes an excellent performance-enhancing drug, and professional athletes who dope with it often develop a form of acromegaly. In short, their skulls and jawbones swell, and their hat and helmet sizes increase markedly.
40. his two thousandth brain tumor: Eleven of those two thousand tumors came from the noggin of one man, Tim Donovan. Cushing eventually removed 47 ounces of cancerous tissue from Donovan’s skull—the equivalent of a full extra brain.
41. pings the hypothalamus: On March 29, 1916, a Mr. O. in north-central Iowa shot himself through the right temple. Someone discovered him a dozen hours later, and a doctor revived him at a local hospital. The bullet severed O.’s optic nerves and he woke up blind, but the complication that made his case memorable didn’t start until a few days later. During the first two days of convalescence O. urinated just 14 ounces total (0.1 gallons). On day five the floodgates opened, and he began peeing, and peeing—and peeing. By April 10 he was peeing 1.2 gallons daily, three times what an average male should. And that doesn’t include the three times he wet his bed. On April 12 he peed 1.5 gallons, again not counting accidents.
His doctor eventually traced this Niagara to the hypothalamus, which scientists now know manufactures a neurotransmitter called vasopressin. Vasopressin, after seeping into the bloodstream, turns on pumps in the kidneys that reabsorb H2O and keep it out of the bladder. O.’s shot hadn’t hit the hypothalamus directly, but brain tissue along the bullet’s path swelled and slowly crushed it. When vasopressin production shut down, his rapidly filling bladder had no choice but bail and bail and bail some more. O. spent the rest o
f his sad life in an asylum.
As another example of the limbic circuit interacting with the wider body, consider the case of Rita Hoefling, a forty-year-old white South African housewife. Surgeons removed Hoefling’s adrenal glands in the early 1970s after diagnosing her with Cushing’s syndrome, which occurs when the adrenals release too much cortisol. The surgery stopped that problem but stirred up other trouble. The adrenals check the activity of the pituitary gland, and with nothing holding the pituitary back now, it began to churn out hormones that increase the production of melanin inside skin cells. Melanin changes the color of skin, and Hoefling began to turn bronze, then light brown, as a result. This well-known side effect of removing the adrenals (Nelson’s syndrome) wouldn’t have caused much of a stir—except in apartheid South Africa. Hoefling started getting thrown off whites-only buses. Her husband and son abandoned her. She was even barred from her father’s funeral. After her ostracism, the colored community magnanimously embraced Hoefling, and she later spoke out against the evils of apartheid.
42. yawns: Yawns are a rich neuroscientific subject. As with smiles, some people who are paralyzed due to a stroke in the motor area can still reach out and stretch their arms if induced to yawn. That’s because the yawn reflex originates in the brainstem and can therefore bypass the damaged neurons and access the arm muscles through different channels. The origin in the brainstem also implies that yawning is an ancient reflex, far older than humanity. And sure enough, many other mammals yawn, as do snakes, birds, and turtles. Humans born with only a brainstem (i.e., without the higher parts of the brain) can also yawn, as can fetuses in the womb.