Читать книгу Proust Was a Neuroscientist - Jonah Lehrer - Страница 13

Modern neuroscience is now discovering the anatomy underlying Whitman’s poetry. It has taken his poetic hypothesis — the idea that feelings begin in the flesh — and found the exact nerves and brain regions that make it true. Antonio Damasio, a neuroscientist who has done extensive work on the etiology of feeling, calls this process the body loop. In his view, the mind stalks the flesh; from our muscles we steal our moods.

How does the brain generate our metaphysical feelings from the physical body? According to Damasio, after an “emotive stimulus” (such as a bear) is seen, the brain automatically triggers a wave of changes in the “physical viscera,” as the body prepares for action. The heart begins to pound, arteries dilate, the intestines contract, and adrenaline pours into the bloodstream. These bodily changes are then detected by the cortex, which connects them to the scary sensation that caused the changes in the first place. The resulting mental image — an emulsion of thought and flesh, body and soul — is what we feel. It is an idea that has passed through the vessel of the body.

Over the course of his distinguished career, Damasio has chronicled the lives of patients whose brains have been injured and who, as a result, are missing this intricate body-brain connection. Although they maintain full sensory awareness, these patients are unable to translate their sensations into emotions. The pounding of the heart never becomes a feeling of fear. Because the mind is divorced from the flesh, the patient lives in a cocoon of numbness — numb even to his or her own tragedy.

Damasio’s research has elaborated on the necessity of our carnal emotions. His conclusions are Whitmanesque. “The body contributes more than life support,” Damasio writes. “It contributes a content that is part and parcel of the workings of the normal mind.” In fact, even when the body does not literally change, the mind creates a feeling by hallucinating a bodily change. Damasio calls this the asif body loop, since the brain acts as if the body were experiencing a real physical event. By imagining a specific bodily state — like a fast heartbeat, or a surge of adrenaline — the mind can induce its own emotions.

One of Damasio’s most surprising discoveries is that the feelings generated by the body are an essential element of rational thought. Although we typically assume that our emotions interfere with reason, Damasio’s emotionless patients proved incapable of making reasonable decisions. After suffering their brain injuries, all began displaying disturbing changes in behavior. Some made terrible investments and ended up bankrupt; others became dishonest and antisocial; most just spent hours deliberating over irrelevant details. According to Damasio, their frustrating lives are vivid proof that rationality requires feeling, and feeling requires the body. (As Nietzsche put it, “There is more reason in your body than in your best wisdom.”)

Of course, it’s hard to make generalizations about the brain based on a few neurological patients. In order to understand how the body loop functions in the normal mind, Damasio devised an ingenious experiment he called the gambling task. The experiment went as follows: a subject — the player — was given four decks of cards, two black and two red, and $2,000 worth of play money. Each card told the player that he had either won or lost money. The subject was instructed to turn over a card from one of the four decks and to make as much money as possible.

But the cards weren’t distributed at random. Damasio rigged the game. Two of the decks were full of high-risk cards. These decks had bigger payouts ($100), but also contained extravagant monetary punishments ($1,250). The other two decks, by comparison, were staid and conservative. Although they had smaller payouts ($50), they rarely punished the player. If the gamblers only drew from these two decks, they would come out way ahead.

At first, the card-selection process was entirely random. The player had no reason to favor any specific deck, and so they sampled from each pile, searching for money-making patterns. On average, people had to turn over about fifty cards before they began to only draw from the profitable decks. It took about eighty cards before the average experimental subject could explain why they favored those decks. Logic is slow.

But Damasio wasn’t interested in logic. He was interested in the body. He attached electrodes to the subjects’ palms and measured the electrical conductance of their skin. (As Whitman noted in “I Sing the Body Electric,” the body is electric, our nerves singing with minor voltages.)* In general, higher levels of conductance in the skin signal nervousness. What Damasio found was that after drawing only ten cards, the hand of the experimental subject got “nervous” whenever it reached for one of the negative decks. While the brain had yet to completely understand the game (and wouldn’t for another forty cards), the subject’s hand “knew” what deck to draw from. Furthermore, as the hand grew increasingly electric, the subject started drawing more and more frequently from the advantageous decks. The unconscious feelings generated by the body preceded the conscious decision. The hand led the mind.

Whitman would have loved this experiment. In the same poem where he declares the body electric, he also exclaims about “the curious sympathy one feels when feeling with the hand.” Long before Damasio, Whitman understood that “the spirit receives from the body just as much as it gives to the body.” This is why he listened so closely to his flesh: it was the place where his poetry began.

But Whitman also knew that his poems were not simply odes to the material body. This was the mistake that his Victorian critics made: by taking his references to orgasms and organs literally, they missed his true poetic epiphany. The moral of Whitman’s verse was that the body wasn’t merely a body. Just as leaves of grass grow out of the dirt, feelings grow out of the flesh. What Whitman wanted to show was how these two different substances — the grass and the dirt, the body and the mind — were actually inseparable. You couldn’t write poems about one without acknowledging the presence of the other. As Whitman declared, “I will make the poems of materials, for I think they are to be the most spiritual poems.”

This faith in the holiness of everything, even the low things, ultimately led Whitman to dispute the facts of science. When the materialists of his time announced that the body was nothing but an evolved machine — there was no soul inside — Whitman reacted with characteristic skepticism. He believed that no matter how much we knew about our physical anatomy, the ineffable would always remain. This is why he wrote poetry. “Hurray for positive science,” Whitman wrote. “Gentlemen, to you the first honors always! / Your facts are useful, and yet they are not my dwelling, / I but enter them to an area of my dwelling.”

What Emerson said of Montaigne is true of Whitman too: if you cut his words, they will bleed, “for they are vascular and alive.” Whitman’s poetry describes our anatomical reality. In the mirror of his art, we see the stark fact of our own improbability. Feeling from flesh? Soul from body? Body from soul? Our existence makes no sense. We live inside a contradiction. Whitman exposes this truth, and then, in the very next sentence, accepts it. His only answer is that there is no answer. “I and this mystery, here we stand,” Whitman once said, and that pretty much says it all.

A photograph of Walt Whitman in 1891, just a few months before he died. The photograph was taken by the painter Thomas Eakins.

Yet the acceptance of contradiction has its own consequences. As Randall Jarrell wrote in an essay on Whitman, “When you organize one of the contradictory elements out of your work of art, you are getting rid not just of it, but of the contradiction of which it was a part; and it is the contradictions in works of art which make them able to represent us — as logical and methodical generalizations cannot — our world and our selves, which are also full of contradictions.” By trusting his experience, no matter how paradoxical it might seem, Whitman discovered our anatomical reality. Despite the constant calls for his censure, he never doubted the wisdom of his art. “Now I see it is true, what I guess’d at,” Whitman wrote in “Song of Myself.” What he guessed at, of course, is that the soul is made of flesh.

For a self-described poet of the body, Whitman’s own body was in dreadful shape. Although he often bragged about “the exquisite realization of his health,” by the time Whitman died, in the early spring of 1892, his health had been damaged by years of neglect and disease. The doctors who performed his autopsy — they began cutting as soon as Thomas Eakins finished making Whitman’s death mask — were startled at the state of his insides. His left lung had collapsed, and only an eighth of his right lung seemed to be in workable condition. Tuberculosis, which he had gotten while serving as a nurse during the Civil War, had chronically inflamed his stomach, liver, and kidneys. He had pneumonia. His heart was swollen. In fact, the only organ which still seemed to be functional was Whitman’s brain. Just two months earlier, he had finished compiling his final edition of Leaves of Grass, which became the “Death-Bed” edition. As usual, he had revised his old poems and continued to write new ones.

What could Whitman have been thinking as he felt his flesh — his trusted muse — slowly abandon him? He began this last Leaves of Grass with a new epigraph, written in death’s shadow:

Come, said my soul,

Such verses for my Body let us write, (for we are one).

These two poignant lines, the first lines in the last version of his only book of poetry, represent the distilled essence of Whitman’s philosophy. We are the poem, his poem says, that emerges from the unity of the body and the mind. That fragile unity — this brief parenthesis of being — is all we have. Celebrate it.

* The single biggest failing of phrenology was its inability to assimilate data that didn’t conform to its predictions. For example, when phrenologists measured Descartes’s skull, they found an extremely small forehead, which implied “limited logical and rational faculties.” But instead of doubting their original hypothesis, the phrenologists lampooned Descartes and declared “that he was not so great a thinker as he was held to be.”

† Although Whitman loved learning about science, he never accepted its findings uncritically. In his notebook, Whitman reminded himself to always question the veracity of its experiment: “Remember in scientific and similar allusions that the theories of Geology, History, Language, &c., &c., are continually changing. Be careful to put in only what must be appropriate centuries hence.”

* Whitman was not alone; everyone from Mark Twain to Edgar Allan Poe underwent phrenological exams. George Eliot shaved her head so that her phrenologist could make a more accurate diagnosis of her cranial bumps.

* One of the reasons that Whitman seems to have moderated his views on phrenology was that he had a very favorable skull. He scored nearly perfect on virtually every possible phrenological trait. Oddly enough, two of his lowest scores were for the traits of tune and language.

* “The lung sponges, the stomach-sac, the bowels sweet and clean, The brain in its folds inside the skull frame, Sympathies, heart-valves, palate valves, sexuality, maternity …” [129]

* Later on in his life, Weir Mitchell would abandon medicine entirely and devote himself to writing novels and poetry. His novel Hugh Wynne (1897) — about the experiences of a Quaker during the American Revolution — was particularly popular.

* Sadly, it would take another thirty years — and another brutal war — before sensory ghosts were rediscovered. In 1917, confronted by the maimed soldiers of WWI, the neurologist J. Babinski described his own version of sensory ghosts. He makes no mention of Herman Melville, William James, or Weir Mitchell.

* As a pragmatist, James also believed that feelings — and not some sort of pure Cartesian reason — were the motivation behind most of our beliefs. In “The Will to Believe,” James remarked that “these feelings of our duty about either truth or error are in any case only expressions of our passional life … Objective evidence and certitude are doubtless very fine ideals to play with, but where on this moonlit and dream-visited planet are they found?” Although James’s essay sparked a firestorm of controversy, he was really just taking David Hume’s claim that “reason is, and ought to be, the slave of the passions” to its logical conclusion.

* A year after James’s article was published, the Danish psychologist Carl Lange published a similar theory about body and emotion, leading scientists to refer to the theory as the James-Lange hypothesis.

* At the time of Whitman’s writing, there was very little evidence that the body pulsated with charged ions. Luigi Galvani’s discovery in the 1780s that frogs’ legs twitched when shocked remained hotly disputed. In fact, it was not until 1875, twenty years after Whitman first sang of electric bodies, that Richard Caton, a Liverpool physician, discovered that Whitman was right, the nervous system actually conveys electric current. Caton demonstrated this improbable fact by probing directly on the exposed brains of animals with a reflecting galvanometer (a newly invented device that was able to sense the low voltages of neurons).