July 8, 2014 8:29:07 AM
If our brains are functioning the right way, we can see straight, we have good recall of memories important and trivial, we can express ourselves, and we can do a thousand other important things. That's business as usual (and we ought to take some time every day to think about how astonishing that "usual" is). We take well-functioning brains for granted, partially because the billions of neurons silently send out their billions of signals every second and we have no way of accessing what is going on with them even as they make us "us." It is when things go wrong that we can learn stuff about how brains do their jobs. In fact, before CAT scans and MRIs and EEGs, injured brains that produced particular symptoms were the only way to tell what the mysterious organs were supposed to be doing had they been uninjured. The history of understanding brain injuries and the diverse symptoms that result is the engrossing subject of The Tale of the Dueling Neurosurgeons: The History of the Human Brain as Revealed by True Stories of Trauma, Madness, and Recovery (Little, Brown) by science writer Sam Kean. It is a fine story of centuries of scientific effort, with case histories of bizarre symptoms that ought to make all of us a little more grateful about all our brains can do.
We accept that brains are where the thoughts and feelings come from, the organ that more than any other gives us our "selves." This seems intuitive now, but even this basic idea did not come easily. For far longer than we have considered the brain the seat of the mind (and of the soul, whatever that is), we thought the heart was the headquarters. In their embalming practices, the ancient Egyptians preserved carefully the heart, but they scraped out the brain (which might have been fed to animals) and filled the head with sawdust. Aristotle knew that the heart had plenty of thick vessels leading everywhere in the body, and it was right at the center of things, so it had to be more important than the brain that had wispy wirings and was far removed at the top. Even anatomists knew that in embryos, the heart was the first organ to form, and doctors could measure that heart rate went up in response to emotions. Doctors also, however, increasingly realized that a blow to the head could cause important changes in functioning, even in personality. It wasn't until around the 1600s that most informed thinkers credited the brain with being the center of human nature.
Knowing the brain was the headquarters, though, was much different from knowing how it worked, and to be sure, we are far from understanding the workings even now. A chief argument over the centuries was whether the mass of the brain as a whole did all the work of thinking and acting, or whether the brain had circumscribed, specialized regions to do specific tasks. Even in the nineteenth century, the idea that there was localization to brain functions was frowned upon. After all, the phrenologists had insisted that particular bumps and swellings of the head and brain lobes indicated, say, a tendency toward atheism or toward eating meat. Phrenology had been wildly fashionable, but had been debunked, and a whiff of quackery stuck to the doctors who first started showing that a lesion in a certain brain area could be expected to result in certain symptoms. The cases, however, mounted up: seizures, strokes, diverse diseases, accidents, and the injuries of war all produced awful injuries to the brain, as sometimes did surgery that went awry or had unexpected side effects. We all know now that right brains have functions different from left brains, and we know that vision, speech, hand control, and even emotion have certain centers involved.
The historical case studies here show how this revolution in thinking occurred, and they are the most fascinating parts of this book. Those who know the books by Oliver Sacks will be acquainted with cases like these, only these generally are historic cases that engendered some particular scientific understanding. To be sure Kean includes the story of Phineas Gage, perhaps the most famous tale in neuroscience. He was a reliable and popular railway foreman, but in 1848 an explosion drove a steel rod through his skull. The huge injury didn't kill him, though he did lose an eye. He also lost his calmness, reverence, and thoughtfulness, becoming eccentric, coarse, and foul-mouthed. He had had an artificial lobotomy, and though Gage lived, his friends all agreed he was "no longer Gage." Strangely, he did not even lose consciousness after the injury. Kean contrasts this with the modern case of classical composer Clive Wearing, who had a spell of meningitis which affected his limbic system. As a result, he has no short term memory; every day is new, and he has the experience over and over again that he is just resuming being conscious. When he tried to anchor his past with a diary, the entries were like this:
"8:31 AM. Now I am really, completely awake." He would cross that out, and underneath write:
"9:06 AM. Now I am perfectly, overwhelmingly awake." He would cross that out and underneath write:
"9:34 AM: Now I am superlatively, actually awake."
He perceived each entry in turn as clearly false, so he crossed it out as he resumed consciousness again (although he never lost it, as far as observers could tell), and he filled whole pages this way. Not only does he lose his past like an amnesiac, he is condemned to deny his past even exists.
The book's title comes from an important historical case. King Henri II of France in 1559 recklessly took part in a jousting contest and got a lance through his eye, plus he had some sort of brain injury. (French kings were thereafter prohibited from jousting.) Two of the greatest of physicians at the time were called to attend him, Ambroise Pare and Andreas Vesalius. There was little they could do, as the king had seizures and went in and out of consciousness and blindness, and ten days after the accident he was dead. It is quite astonishing that Queen Catherine allowed the surgeons to do an autopsy, as such research was rare at the time. The surgeons noted with amazement that the king's skull was intact; before this it was thought that if the skull was uninjured, the brain would have to be, too. The king's brain had been battered within the skull, with a hemorrhage at the rear. Kean explains that this revolutionary understanding that a closed skull does not mean an intact brain is still not fully learned; we are only recently, for instance, asking to what degree concussions are damaging the cranial contents of our high school or professional football players.
There are many strange syndromes here. A girl had a normal childhood, but at age ten the cells in her amygdala died off, making it impossible for her to feel fear. Studies on her, Kean says, "are a hoot to read, since they consist of scientists dreaming up ever-more-elaborate ways to scare her." Snakes, haunted houses with monsters in costume, and more have all been tried, but nothing frightens her, although she is pretty normal in all other ways. The famous H. M. had surgery to stop his seizures, and they stopped; his personality originally stayed the same, and all was well, except his ability to remember things was gone. He could not remember if he had eaten or not, or follow instructions to get to the bathroom a second time. He could mow the lawn for his parents; it was obvious to him what part of the lawn had been cut and what remained, but his parents had to tell him every time where they kept the mower. On the other hand, Solomon Shereshevsky could not forget anything, with his mind full of unedited impressions that left him confused and helpless to get on in the world. Toxins and blows to the head can cause Capgras Syndrome, whose sufferers are sure that everyone they know has been replaced by a sinister double. One made a confession of bigamy to his priest, since he had married his wife originally and now was married to her replacement who looked and acted just like the original, but wasn't. A man with normal sexual urges became a pedophile once a brain tumor pressed just so; surgical removal of the tumor reversed the pedophilia.
All of these cases make a reader wonder, "Who is in charge here?" If a little bleeding or an intruding tumor can make such changes, where is the real person? From neurons through neural tracts through brain specialization centers and all the way through to the process of consciousness (that "defining problem of neuroscience"), Kean's storytelling is masterful and his explanations graceful. The best part is that we have barely started. We have only been doing neuroscience for a few centuries, and there are still so many mysteries left within the three pound mass we all carry in our crania.