COMPASSIONATE HEALTHCARE NETWORK (C H N )
Thursday, Jan. 18, 2007
When it came to moral "reasoning," David Hume emphasized the quotation marks. We like to think our views on right and wrong are rational, he said, but ultimately they are grounded in emotion.
Philosophers have argued over this claim for a quarter of a millennium without resolution. Time's up! Now scientists armed with brain scanners are stepping in to settle the matter. So far it looks like Hume was onto something; though reason can shape moral judgment, emotion is often decisive, and that explains some strange quirks in our moralizing.
Harvard psychologist Joshua Greene does brain scans of people as they ponder the so-called trolley problem. Suppose a trolley is rolling down the track toward five people who will die unless you pull a lever that diverts it onto another track--where, unfortunately, lies one person who will die instead. An easy call, most people say: minimizing the loss of life--a "utilitarian" goal, as philosophers put it--is the right thing to do.
But suppose the only way to save the five people is to push someone else onto the track--a bystander whose body will bring the trolley to a halt before it hits the others. It's still a one-for-five swap, and you still initiate the action that dooms the one--but now you are more directly implicated; most people say it would be wrong to do this deal. Why? According to Greene's brain scans, the second scenario--the "up close and personal" intervention, he calls it--more thoroughly excites parts of the brain linked to emotion than does the lever-pulling scenario. Apparently the intuitive aversion to giving someone a lethal push is stronger than the aversion to a lethal lever pull.
Further studies suggest that in both cases the emotional aversion competes for control with more rational parts of the brain that take a utilitarian view, emphasizing the net savings of four lives. In the up-close-and-personal scenario the emotions are usually strong enough to win.
And when they lose, it is only after a tough wrestling match. The few people who approve of pushing an innocent man onto the tracks take longer to reach their decision. So too with people who approve of smothering a crying baby rather than catching the attention of enemy troops who would then kill the baby along with other innocents.
These cranial wrestling matches could be televised. As people ponder a moral dilemma, brain scans show changing activity levels in a part of the brain linked to abstract reasoning and cognitive control. In brains that take the utilitarian path, this part strengthens until dominant; in brains that refuse to kill one innocent to save many, it weakens until emotion has won.
Greene explains his findings in Darwinian terms. Back in the hunter-gatherer environment of human evolution, you killed people directly, not by the triple bank shot of pulling a lever that shifted a plate that rerouted a train. So an evolved aversion to the killing of an innocent might be especially sensitive to visions of direct physical assault. Imagining the triple bank shot impacts us less viscerally, causing a weaker aversion that is more easily outweighed by calculation.
Princeton philosopher Peter Singer cites Greene's work in arguing that we should re-examine our moral intuitions and ask not just whether these impulses still serve their original evolutionary logic, but whether that logic merits respect in the first place. Why obey moral impulses that evolved to serve what Richard Dawkins calls the "selfish gene"--such as sympathy that gravitates toward kin and friends? Why not worry more about people an ocean away whose suffering we could cheaply alleviate? Isn't it better to save 10 starving African babies than to keep your 90-year-old father on life support?
Singer's radically utilitarian brand of moral philosophy has its work cut out for it. In the absence of arduous cranial wrestling matches, reason may indeed be, as Hume famously put it, "slave of the passions."
Wright is a Schwartz senior fellow at the New America Foundation and author of Nonzero and The Moral Animal
Friday, Jan. 19, 2007
The young women had survived the car crash, after a fashion. In the five months since parts of her brain had been crushed, she could open her eyes but didn't respond to sights, sounds or jabs. In the jargon of neurology, she was judged to be in a persistent vegetative state. In crueler everyday language, she was a vegetable.
So picture the astonishment of British and Belgian scientists as they scanned her brain using a kind of MRI that detects blood flow to active parts of the brain. When they recited sentences, the parts involved in language lit up. When they asked her to imagine visiting the rooms of her house, the parts involved in navigating space and recognizing places ramped up. And when they asked her to imagine playing tennis, the regions that trigger motion joined in. Indeed, her scans were barely different from those of healthy volunteers. The woman, it appears, had glimmerings of consciousness.
Try to comprehend what it is like to be that woman. Do you appreciate the words and caresses of your distraught family while racked with frustration at your inability to reassure them that they are getting through? Or do you drift in a haze, springing to life with a concrete thought when a voice prods you, only to slip back into blankness? If we could experience this existence, would we prefer it to death? And if these questions have answers, would they change our policies toward unresponsive patients--making the Terri Schiavo case look like child's play?
The report of this unusual case last September was just the latest shock from a bracing new field, the science of consciousness. Questions once confined to theological speculations and late-night dorm-room bull sessions are now at the forefront of cognitive neuroscience. With some problems, a modicum of consensus has taken shape. With others, the puzzlement is so deep that they may never be resolved. Some of our deepest convictions about what it means to be human have been shaken.
It shouldn't be surprising that research on consciousness is alternately exhilarating and disturbing. No other topic is like it. As René Descartes noted, our own consciousness is the most indubitable thing there is. The major religions locate it in a soul that survives the body's death to receive its just deserts or to meld into a global mind. For each of us, consciousness is life itself, the reason Woody Allen said, "I don't want to achieve immortality through my work. I want to achieve it by not dying." And the conviction that other people can suffer and flourish as each of us does is the essence of empathy and the foundation of morality.
To make scientific headway in a topic as tangled as consciousness, it helps to clear away some red herrings. Consciousness surely does not depend on language. Babies, many animals and patients robbed of speech by brain damage are not insensate robots; they have reactions like ours that indicate that someone's home. Nor can consciousness be equated with self-awareness. At times we have all lost ourselves in music, exercise or sensual pleasure, but that is different from being knocked out cold.
THE "EASY" AND "HARD" PROBLEMS
WHAT REMAINS IS NOT ONE PROBLEM ABOUT CONSCIOUSNESS BUT two, which the philosopher David Chalmers has dubbed the Easy Problem and the Hard Problem. Calling the first one easy is an in-joke: it is easy in the sense that curing cancer or sending someone to Mars is easy. That is, scientists more or less know what to look for, and with enough brainpower and funding, they would probably crack it in this century.
What exactly is the Easy Problem? It's the one that Freud made famous, the difference between conscious and unconscious thoughts. Some kinds of information in the brain--such as the surfaces in front of you, your daydreams, your plans for the day, your pleasures and peeves--are conscious. You can ponder them, discuss them and let them guide your behavior. Other kinds, like the control of your heart rate, the rules that order the words as you speak and the sequence of muscle contractions that allow you to hold a pencil, are unconscious. They must be in the brain somewhere because you couldn't walk and talk and see without them, but they are sealed off from your planning and reasoning circuits, and you can't say a thing about them.
The Easy Problem, then, is to distinguish conscious from unconscious mental computation, identify its correlates in the brain and explain why it evolved.
The Hard Problem, on the other hand, is why it feels like something to have a conscious process going on in one's head--why there is first-person, subjective experience. Not only does a green thing look different from a red thing, remind us of other green things and inspire us to say, "That's green" (the Easy Problem), but it also actually looks green: it produces an experience of sheer greenness that isn't reducible to anything else. As Louis Armstrong said in response to a request to define jazz, "When you got to ask what it is, you never get to know."
The Hard Problem is explaining how subjective experience arises from neural computation. The problem is hard because no one knows what a solution might look like or even whether it is a genuine scientific problem in the first place. And not surprisingly, everyone agrees that the hard problem (if it is a problem) remains a mystery.
Although neither problem has been solved, neuroscientists agree on many features of both of them, and the feature they find least controversial is the one that many people outside the field find the most shocking. Francis Crick called it "the astonishing hypothesis"--the idea that our thoughts, sensations, joys and aches consist entirely of physiological activity in the tissues of the brain. Consciousness does not reside in an ethereal soul that uses the brain like a PDA; consciousness is the activity of the brain.
THE BRAIN AS MACHINE
SCIENTISTS HAVE EXORCISED THE GHOST FROM THE MACHINE NOT because they are mechanistic killjoys but because they have amassed evidence that every aspect of consciousness can be tied to the brain. Using functional MRI, cognitive neuroscientists can almost read people's thoughts from the blood flow in their brains. They can tell, for instance, whether a person is thinking about a face or a place or whether a picture the person is looking at is of a bottle or a shoe.
And consciousness can be pushed around by physical manipulations. Electrical stimulation of the brain during surgery can cause a person to have hallucinations that are indistinguishable from reality, such as a song playing in the room or a childhood birthday party. Chemicals that affect the brain, from caffeine and alcohol to Prozac and LSD, can profoundly alter how people think, feel and see. Surgery that severs the corpus callosum, separating the two hemispheres (a treatment for epilepsy), spawns two consciousnesses within the same skull, as if the soul could be cleaved in two with a knife.
And when the physiological activity of the brain ceases, as far as anyone can tell the person's consciousness goes out of existence. Attempts to contact the souls of the dead (a pursuit of serious scientists a century ago) turned up only cheap magic tricks, and near death experiences are not the eyewitness reports of a soul parting company from the body but symptoms of oxygen starvation in the eyes and brain. In September, a team of Swiss neuroscientists reported that they could turn out-of-body experiences on and off by stimulating the part of the brain in which vision and bodily sensations converge.
THE ILLUSION OF CONTROL
ANOTHER STARTLING CONCLUSION FROM the science of consciousness is that the intuitive feeling we have that there's an executive "I" that sits in a control room of our brain, scanning the screens of the senses and pushing the buttons of the muscles, is an illusion. Consciousness turns out to consist of a maelstrom of events distributed across the brain. These events compete for attention, and as one process outshouts the others, the brain rationalizes the outcome after the fact and concocts the impression that a single self was in charge all along.
Take the famous cognitive-dissonance experiments. When an experimenter got people to endure electric shocks in a sham experiment on learning, those who were given a good rationale ("It will help scientists understand learning") rated the shocks as more painful than the ones given a feeble rationale ("We're curious.") Presumably, it's because the second group would have felt foolish to have suffered for no good reason. Yet when these people were asked why they agreed to be shocked, they offered bogus reasons of their own in all sincerity, like "I used to mess around with radios and got used to electric shocks."
It's not only decisions in sketchy circumstances that get rationalized but also the texture of our immediate experience. We all feel we are conscious of a rich and detailed world in front of our eyes. Yet outside the dead center of our gaze, vision is amazingly coarse. Just try holding your hand a few inches from your line of sight and counting your fingers. And if someone removed and reinserted an object every time you blinked (which experimenters can simulate by flashing two pictures in rapid sequence), you would be hard pressed to notice the change. Ordinarily, our eyes flit from place to place, alighting on whichever object needs our attention on a need-to-know basis. This fools us into thinking that wall-to-wall detail was there all along--an example of how we overestimate the scope and power of our own consciousness.
Our authorship of voluntary actions can also be an illusion, the result of noticing a correlation between what we decide and how our bodies move. The psychologist Dan Wegner studied the party game in which a subject is seated in front of a mirror while someone behind him extends his arms under the subject's armpits and moves his arms around, making it look as if the subject is moving his own arms. If the subject hears a tape telling the person behind him how to move (wave, touch the subject's nose and so on), he feels as if he is actually in command of the arms.
The brain's spin doctoring is displayed even more dramatically in neurological conditions in which the healthy parts of the brain explain away the foibles of the damaged parts (which are invisible to the self because they are part of the self). A patient who fails to experience a visceral click of recognition when he sees his wife but who acknowledges that she looks and acts just like her deduces that she is an amazingly well-trained impostor. A patient who believes he is at home and is shown the hospital elevator says without missing a beat, "You wouldn't believe what it cost us to have that installed."
Why does consciousness exist at all, at least in the Easy Problem sense in which some kinds of information are accessible and others hidden? One reason is information overload. Just as a person can be overwhelmed today by the gusher of data coming in from electronic media, decision circuits inside the brain would be swamped if every curlicue and muscle twitch that was registered somewhere in the brain were constantly being delivered to them. Instead, our working memory and spotlight of attention receive executive summaries of the events and states that are most relevant to updating an understanding of the world and figuring out what to do next. The cognitive psychologist Bernard Baars likens consciousness to a global blackboard on which brain processes post their results and monitor the results of the others.
BELIEVING OUR OWN LIES
A SECOND REASON THAT INFORMATION MAY BE SEALED OFF FROM consciousness is strategic. Evolutionary biologist Robert Trivers has noted that people have a motive to sell themselves as beneficent, rational, competent agents. The best propagandist is the one who believes his own lies, ensuring that he can't leak his deceit through nervous twitches or self-contradictions. So the brain might have been shaped to keep compromising data away from the conscious processes that govern our interaction with other people. At the same time, it keeps the data around in unconscious processes to prevent the person from getting too far out of touch with reality.
What about the brain itself? You might wonder how scientists could even begin to find the seat of awareness in the cacophony of a hundred billion jabbering neurons. The trick is to see what parts of the brain change when a person's consciousness flips from one experience to another. In one technique, called binocular rivalry, vertical stripes are presented to the left eye, horizontal stripes to the right. The eyes compete for consciousness, and the person sees vertical stripes for a few seconds, then horizontal stripes, and so on.
A low-tech way to experience the effect yourself is to look through a paper tube at a white wall with your right eye and hold your left hand in front of your left eye. After a few seconds, a white hole in your hand should appear, then disappear, then reappear.
Monkeys experience binocular rivalry. They can learn to press a button every time their perception flips, while their brains are impaled with electrodes that record any change in activity. Neuroscientist Nikos Logothetis found that the earliest way stations for visual input in the back of the brain barely budged as the monkeys' consciousness flipped from one state to another. Instead, it was a region that sits further down the information stream and that registers coherent shapes and objects that tracks the monkeys' awareness. Now this doesn't mean that this place on the underside of the brain is the TV screen of consciousness. What it means, according to a theory by Crick and his collaborator Christof Koch, is that consciousness resides only in the "higher" parts of the brain that are connected to circuits for emotion and decision making, just what one would expect from the blackboard metaphor.
WAVES OF BRAIN
CONSCIOUSNESS IN THE BRAIN CAN BE TRACKED NOT JUST IN SPACE but also in time. Neuroscientists have long known that consciousness depends on certain frequencies of oscillation in the electroencephalograph (EEG). These brain waves consist of loops of activation between the cortex (the wrinkled surface of the brain) and the thalamus (the cluster of hubs at the center that serve as input-output relay stations). Large, slow, regular waves signal a coma, anesthesia or a dreamless sleep; smaller, faster, spikier ones correspond to being awake and alert. These waves are not like the useless hum from a noisy appliance but may allow consciousness to do its job in the brain. They may bind the activity in far-flung regions (one for color, another for shape, a third for motion) into a coherent conscious experience, a bit like radio transmitters and receivers tuned to the same frequency. Sure enough, when two patterns compete for awareness in a binocular-rivalry display, the neurons representing the eye that is "winning" the competition oscillate in synchrony, while the ones representing the eye that is suppressed fall out of synch.
So neuroscientists are well on the way to identifying the neural correlates of consciousness, a part of the Easy Problem. But what about explaining how these events actually cause consciousness in the sense of inner experience--the Hard Problem?
TACKLING THE HARD PROBLEM
TO APPRECIATE THE HARDNESS OF THE HARD PROBLEM, CONSIDER how you could ever know whether you see colors the same way that I do. Sure, you and I both call grass green, but perhaps you see grass as having the color that I would describe, if I were in your shoes, as purple. Or ponder whether there could be a true zombie--a being who acts just like you or me but in whom there is no self actually feeling anything. This was the crux of a Star Trek plot in which officials wanted to reverse-engineer Lieut. Commander Data, and a furious debate erupted as to whether this was merely dismantling a machine or snuffing out a sentient life.
No one knows what to do with the Hard Problem. Some people may see it as an opening to sneak the soul back in, but this just relabels the mystery of "consciousness" as the mystery of "the soul"--a word game that provides no insight.
Many philosophers, like Daniel Dennett, deny that the Hard Problem exists at all. Speculating about zombies and inverted colors is a waste of time, they say, because nothing could ever settle the issue one way or another. Anything you could do to understand consciousness--like finding out what wavelengths make people see green or how similar they say it is to blue, or what emotions they associate with it--boils down to information processing in the brain and thus gets sucked back into the Easy Problem, leaving nothing else to explain. Most people react to this argument with incredulity because it seems to deny the ultimate undeniable fact: our own experience.
The most popular attitude to the Hard Problem among neuroscientists is that it remains unsolved for now but will eventually succumb to research that chips away at the Easy Problem. Others are skeptical about this cheery optimism because none of the inroads into the Easy Problem brings a solution to the Hard Problem even a bit closer. Identifying awareness with brain physiology, they say, is a kind of "meat chauvinism" that would dogmatically deny consciousness to Lieut. Commander Data just because he doesn't have the soft tissue of a human brain. Identifying it with information processing would go too far in the other direction and grant a simple consciousness to thermostats and calculators--a leap that most people find hard to stomach. Some mavericks, like the mathematician Roger Penrose, suggest the answer might someday be found in quantum mechanics. But to my ear, this amounts to the feeling that quantum mechanics sure is weird, and consciousness sure is weird, so maybe quantum mechanics can explain consciousness.
And then there is the theory put forward by philosopher Colin McGinn that our vertigo when pondering the Hard Problem is itself a quirk of our brains. The brain is a product of evolution, and just as animal brains have their limitations, we have ours. Our brains can't hold a hundred numbers in memory, can't visualize seven-dimensional space and perhaps can't intuitively grasp why neural information processing observed from the outside should give rise to subjective experience on the inside. This is where I place my bet, though I admit that the theory could be demolished when an unborn genius--a Darwin or Einstein of consciousness--comes up with a flabbergasting new idea that suddenly makes it all clear to us.
Whatever the solutions to the Easy and Hard problems turn out to be, few scientists doubt that they will locate consciousness in the activity of the brain. For many nonscientists, this is a terrifying prospect. Not only does it strangle the hope that we might survive the death of our bodies, but it also seems to undermine the notion that we are free agents responsible for our choices--not just in this lifetime but also in a life to come. In his millennial essay "Sorry, but Your Soul Just Died," Tom Wolfe worried that when science has killed the soul, "the lurid carnival that will ensue may make the phrase 'the total eclipse of all values' seem tame."
TOWARD A NEW MORALITY
MY OWN VIEW IS THAT THIS IS backward: the biology of consciousness offers a sounder basis for morality than the unprovable dogma of an immortal soul. It's not just that an understanding of the physiology of consciousness will reduce human suffering through new treatments for pain and depression. That understanding can also force us to recognize the interests of other beings--the core of morality.
As every student in Philosophy 101 learns, nothing can force me to believe that anyone except me is conscious. This power to deny that other people have feelings is not just an academic exercise but an all-too-common vice, as we see in the long history of human cruelty. Yet once we realize that our own consciousness is a product of our brains and that other people have brains like ours, a denial of other people's sentience becomes ludicrous. "Hath not a Jew eyes?" asked Shylock. Today the question is more pointed: Hath not a Jew--or an Arab, or an African, or a baby, or a dog--a cerebral cortex and a thalamus? The undeniable fact that we are all made of the same neural flesh makes it impossible to deny our common capacity to suffer.
And when you think about it, the doctrine of a life-to-come is not such an uplifting idea after all because it necessarily devalues life on earth. Just remember the most famous people in recent memory who acted in expectation of a reward in the hereafter: the conspirators who hijacked the airliners on 9/11.
Think, too, about why we sometimes remind ourselves that "life is short." It is an impetus to extend a gesture of affection to a loved one, to bury the hatchet in a pointless dispute, to use time productively rather than squander it. I would argue that nothing gives life more purpose than the realization that every moment of consciousness is a precious and fragile gift.
Steven Pinker is Johnstone Professor of Psychology at Harvard and the author of The Language Instinct, How the Mind Works and The Blank Slate
Friday, Jan. 19, 2007
It was a fairly modest experiment, as these things go, with volunteers trooping into the lab at Harvard Medical School to learn and practice a little five-finger piano exercise. Neuroscientist Alvaro Pascual-Leone instructed the members of one group to play as fluidly as they could, trying to keep to the metronome's 60 beats per minute. Every day for five days, the volunteers practiced for two hours. Then they took a test.
At the end of each day's practice session, they sat beneath a coil of wire that sent a brief magnetic pulse into the motor cortex of their brain, located in a strip running from the crown of the head toward each ear. The so-called transcranial-magnetic-stimulation (TMS) test allows scientists to infer the function of neurons just beneath the coil. In the piano players, the TMS mapped how much of the motor cortex controlled the finger movements needed for the piano exercise. What the scientists found was that after a week of practice, the stretch of motor cortex devoted to these finger movements took over surrounding areas like dandelions on a suburban lawn.
The finding was in line with a growing number of discoveries at the time showing that greater use of a particular muscle causes the brain to devote more cortical real estate to it. But Pascual-Leone did not stop there. He extended the experiment by having another group of volunteers merely think about practicing the piano exercise. They played the simple piece of music in their head, holding their hands still while imagining how they would move their fingers. Then they too sat beneath the TMS coil.
When the scientists compared the TMS data on the two groups--those who actually tickled the ivories and those who only imagined doing so--they glimpsed a revolutionary idea about the brain: the ability of mere thought to alter the physical structure and function of our gray matter. For what the TMS revealed was that the region of motor cortex that controls the piano-playing fingers also expanded in the brains of volunteers who imagined playing the music--just as it had in those who actually played it.
"Mental practice resulted in a similar reorganization" of the brain, Pascual-Leone later wrote. If his results hold for other forms of movement (and there is no reason to think they don't), then mentally practicing a golf swing or a forward pass or a swimming turn could lead to mastery with less physical practice. Even more profound, the discovery showed that mental training had the power to change the physical structure of the brain.
OVERTHROWING THE DOGMA
FOR DECADES, THE PREVAILING DOGMA IN neuroscience was that the adult human brain is essentially immutable, hardwired, fixed in form and function, so that by the time we reach adulthood we are pretty much stuck with what we have. Yes, it can create (and lose) synapses, the connections between neurons that encode memories and learning. And it can suffer injury and degeneration. But this view held that if genes and development dictate that one cluster of neurons will process signals from the eye and another cluster will move the fingers of the right hand, then they'll do that and nothing else until the day you die. There was good reason for lavishly illustrated brain books to show the function, size and location of the brain's structures in permanent ink.
The doctrine of the unchanging human brain has had profound ramifications. For one thing, it lowered expectations about the value of rehabilitation for adults who had suffered brain damage from a stroke or about the possibility of fixing the pathological wiring that underlies psychiatric diseases. And it implied that other brain-based fixities, such as the happiness set point that, according to a growing body of research, a person returns to after the deepest tragedy or the greatest joy, are nearly unalterable.
But research in the past few years has overthrown the dogma. In its place has come the realization that the adult brain retains impressive powers of "neuroplasticity"--the ability to change its structure and function in response to experience. These aren't minor tweaks either. Something as basic as the function of the visual or auditory cortex can change as a result of a person's experience of becoming deaf or blind at a young age. Even when the brain suffers a trauma late in life, it can rezone itself like a city in a frenzy of urban renewal. If a stroke knocks out, say, the neighborhood of motor cortex that moves the right arm, a new technique called constraint-induced movement therapy can coax next-door regions to take over the function of the damaged area. The brain can be rewired.
The first discoveries of neuroplasticity came from studies of how changes in the messages the brain receives through the senses can alter its structure and function. When no transmissions arrive from the eyes in someone who has been blind from a young age, for instance, the visual cortex can learn to hear or feel or even support verbal memory. When signals from the skin or muscles bombard the motor cortex or the somatosensory cortex (which processes touch), the brain expands the area that is wired to move, say, the fingers. In this sense, the very structure of our brain--the relative size of different regions, the strength of connections between them, even their functions--reflects the lives we have led. Like sand on a beach, the brain bears the footprints of the decisions we have made, the skills we have learned, the actions we have taken.
SCRATCHING A PHANTOM LIMB
AN EXTREME EXAMPLE OF HOW CHANGES IN the input reaching the brain can alter its structure is the silence that falls over the somatosensory cortex after its owner has lost a limb. Soon after a car crash took Victor Quintero's left arm from just above the elbow, he told neuroscientist V.S. Ramachandran of the University of California at San Diego that he could still feel the missing arm. Ramachandran decided to investigate. He had Victor sit still with his eyes closed and lightly brushed the teenager's left cheek with a cotton swab.
Where do you feel that? Ramachandran asked. On his left cheek, Victor answered--and the back of his missing hand. Ramachandran stroked another spot on the cheek. Where do you feel that? On his absent thumb, Victor replied. Ramachandran touched the skin between Victor's nose and mouth. His missing index finger was being brushed, Victor said. A spot just below Victor's left nostril caused the boy to feel a tingling on his left pinkie. And when Victor felt an itch in his phantom hand, scratching his lower face relieved the itch. In people who have lost a limb, Ramachandran concluded, the brain reorganizes: the strip of cortex that processes input from the face takes over the area that originally received input from a now missing hand. That's why touching Victor's face caused brain to "feel" his missing hand.
Similarly, because the regions of cortex that handle sensations from the feet abut those that process sensations from the surface of the genitals, some people who have lost a leg report feeling phantom sensations during sex. Ramachandran's was the first report of a living being knowingly experiencing the results of his brain rewiring.
THINKING ABOUT THINKING
AS SCIENTISTS PROBE the limits of neuroplasticity, they are finding that mind sculpting can occur even without input from the outside world. The brain can change as a result of the thoughts we think, as with Pascual-Leone's virtual piano players. This has important implications for health: something as seemingly insubstantial as a thought can affect the very stuff of the brain, altering neuronal connections in a way that can treat mental illness or, perhaps, lead to a greater capacity for empathy and compassion. It may even dial up the supposedly immovable happiness set point.
In a series of experiments, for instance, Jeffrey Schwartz and colleagues at the University of California, Los Angeles, found that cognitive behavior therapy (CBT) can quiet activity in the circuit that underlies obsessive-compulsive disorder (OCD), just as drugs do. Schwartz had become intrigued with the therapeutic potential of mindfulness meditation, the Buddhist practice of observing one's inner experiences as if they were happening to someone else.
When OCD patients were plagued by an obsessive thought, Schwartz instructed them to think, "My brain is generating another obsessive thought. Don't I know it is just some garbage thrown up by a faulty circuit?" After 10 weeks of mindfulness-based therapy, 12 out of 18 patients improved significantly. Before-and-after brain scans showed that activity in the orbital frontal cortex, the core of the OCD circuit, had fallen dramatically and in exactly the way that drugs effective against OCD affect the brain. Schwartz called it "self-directed neuroplasticity," concluding that "the mind can change the brain."
The same is true when cognitive techniques are used to treat depression. Scientists at the University of Toronto had 14 depressed adults undergo CBT, which teaches patients to view their own thoughts differently--to see a failed date, for instance, not as proof that "I will never be loved" but as a minor thing that didn't work out. Thirteen other patients received paroxetine (the generic form of the antidepressant Paxil). All experienced comparable improvement after treatment. Then the scientists scanned the patients' brains. "Our hypothesis was, if you do well with treatment, your brain will have changed in the same way no matter which treatment you received," said Toronto's Zindel Segal.
But no. Depressed brains responded differently to the two kinds of treatment--and in a very interesting way. CBT muted overactivity in the frontal cortex, the seat of reasoning, logic and higher thought as well as of endless rumination about that disastrous date. Paroxetine, by contrast, raised activity there. On the other hand, CBT raised activity in the hippocampus of the limbic system, the brain's emotion center. Paroxetine lowered activity there. As Toronto's Helen Mayberg explains, "Cognitive therapy targets the cortex, the thinking brain, reshaping how you process information and changing your thinking pattern. It decreases rumination, and trains the brain to adopt different thinking circuits." As with Schwartz's OCD patients, thinking had changed a pattern of activity--in this case, a pattern associated with depression--in the brain.
HAPPINESS AND MEDITATION
COULD THINKING ABOUT THOUGHTS IN A new way affect not only such pathological brain states as OCD and depression but also normal activity? To find out, neuroscientist Richard Davidson of the University of Wisconsin at Madison turned to Buddhist monks, the Olympic athletes of mental training. Some monks have spent more than 10,000 hours of their lives in meditation. Earlier in Davidson's career, he had found that activity greater in the left prefrontal cortex than in the right correlates with a higher baseline level of contentment. The relative left/right activity came to be seen as a marker for the happiness set point, since people tend to return to this level no matter whether they win the lottery or lose their spouse. If mental training can alter activity characteristic of OCD and depression, might meditation or other forms of mental training, Davidson wondered, produce changes that underlie enduring happiness and other positive emotions? "That's the hypothesis," he says, "that we can think of emotions, moods and states such as compassion as trainable mental skills."
With the help and encouragement of the Dalai Lama, Davidson recruited Buddhist monks to go to Madison and meditate inside his functional magnetic resonance imaging (fMRI) tube while he measured their brain activity during various mental states. For comparison, he used undergraduates who had had no experience with meditation but got a crash course in the basic techniques. During the generation of pure compassion, a standard Buddhist meditation technique, brain regions that keep track of what is self and what is other became quieter, the fMRI showed, as if the subjects--experienced meditators as well as novices--opened their minds and hearts to others.
More interesting were the differences between the so-called adepts and the novices. In the former, there was significantly greater activation in a brain network linked to empathy and maternal love. Connections from the frontal regions, so active during compassion meditation, to the brain's emotional regions seemed to become stronger with more years of meditation practice, as if the brain had forged more robust connections between thinking and feeling.
But perhaps the most striking difference was in an area in the left prefrontal cortex--the site of activity that marks happiness. While the monks were generating feelings of compassion, activity in the left prefrontal swamped activity in the right prefrontal (associated with negative moods) to a degree never before seen from purely mental activity. By contrast, the undergraduate controls showed no such differences between the left and right prefrontal cortex. This suggests, says Davidson, that the positive state is a skill that can be trained.
For the monks as well as the patients with depression or OCD, the conscious act of thinking about their thoughts in a particular way rearranged the brain. The discovery of neuroplasticity, in particular the power of the mind to change the brain, is still too new for scientists, let alone the rest of us, to grasp its full meaning. But even as it offers new therapies for illnesses of the mind, it promises something more fundamental: a new understanding of what it means to be human.
Friday, Jan. 19, 2007
David's head was literally stuffed with lung cancer. I was called in to take care of his hip and pelvic bones broken by the growing metastases. His seeming nonchalance about the pain and the surgery was clearly out of concern for his beautiful, young family--his wife Carol, a nurse, and his three kids, who were there every night. He couldn't keep up the carefree charade over the next two weeks, though, as his speech slurred, then became incoherent. He stopped speaking, then moving.
I dreaded making rounds on a patient for whom there was no good news, no good plan. When his doctors rescanned his head, there was barely any brain left. The cerebral machine that talked and wondered, winked and sang, the machine that remembered jokes and birthdays and where the big fish hid on hot days, was nearly gone, replaced by lumps of haphazardly growing gray stuff. Gone with that machine seemed David as well. No expression, no response to anything we did to him. As far as I could tell, he was just not there.
It was particularly bad in the room that Friday when I made evening rounds. The family was there, sad, crying faces on all of them. I fussed with the hip a bit. His respirations had become agonal--the gulping kind of breathing movement that immediately precedes death. I knew Carol had seen this and that she knew what it meant. I said something inane and slid out the door fast, looking importantly at the papers in my hand, striving for the nice, empty corridor. But Carol came after me, needing to catch me away from the kids. Her eyes red-rimmed, she asked me where her husband was. I had noticed the cross around her neck. I said I wasn't sure where he was, but I was pretty sure where he was going. She wanted to believe me, and I think she did.
Saturday morning the sun poured in as I checked the room. The bed was at chest height, made up and empty, with clean, fresh sheets over the vinyl mattress. As I turned to leave, I was blocked by a nurse, an older Irish lady with a doleful look on her face. She had taken care of David last night.
"He woke up, you know, doctor--just after you left--and said goodbye to them all. Like I'm talkin' to you right here. Like a miracle. He talked to them and patted them and smiled for about five minutes. Then he went out again, and he passed in the hour." My eyebrows went up.
Two weeks later I saw Carol in the lobby. It was busy and very public. But before her last "God bless you," I couldn't help asking, "Uh. Carol, did ...?"
She knew my question. With a wide, knowing smile, she nodded and said, "Oh, yes, he sure did." And I believed her.
But it wasn't David's brain that woke him up to say goodbye that Friday. His brain had already been destroyed. Tumor metastases don't simply occupy space and press on things, leaving a whole brain. The metastases actually replace tissue. Where that gray stuff grows, the brain is just not there.
What woke my patient that Friday was simply his mind, forcing its way through a broken brain, a father's final act to comfort his family. The mind is a uniquely personal domain of thought, dreams and countless other things, like the will, faith and hope. These fine things are as real as rocks and water but, like the mind, weightless and invisible, maybe even timeless. Material science shies from these things, calling them epiphenomena, programs running on a computer, tunes on a piano. This understanding can't be ignored; not too much seems to get done on earth without a physical brain. But I know this understanding is not complete, either.
I see the mind have its way all the time when physical realities challenge it. In a patient stubbornly working to rehab after surgery, in a child practicing an instrument or struggling to create, a mind or will, clearly separate, hovers under the machinery, forcing it toward a goal. It's wonderful to see, such tangible evidence of that fine thing's power over the mere clumps of particles that, however pretty, will eventually clump differently and vanish.
Neuroanatomy is largely concerned with which spots in the brain do what; which chemicals have which effects at those spots is neurophysiology. Plan on feeding those chemicals to a real person's brain, and you're doing neuropharmacology. Although they are concerned with myriad, complex, amazing things, none of these disciplines seem to find the mind. Somehow it's "smaller" than the tracts, ganglia and nuclei of the brain's gross anatomy--but "bigger" than the cells and molecules of the brain's physiology. We really should have bumped into it on the way down. Yet we have not. Like our own image in still water, however sharp, when we reach to grasp it, it just dissolves.
But many think the mind is only in there--existing somehow in the physical relationship of the brain's physical elements. The physical, say these materialists, is all there is. I fix bones with hardware. As physical as this might be, I cannot be a materialist. I cannot ignore the internal evidence of my own mind. It would be hypocritical. And worse, it would be cowardly to ignore those occasional appearances of the spirits of others--of minds uncloaked, in naked virtue, like David's goodbye.
Dr. Haig is an assistant clinical professor of orthopedic surgery at the Columbia University College of Physicians and Surgeons
Thursday, Jan. 18, 2007
Trying to map the brain has always been cartography for fools. Most of the other parts of the body reveal their workings with little more than a glance. The heart is self-evidently a pump; the lungs are clearly bellows. But the brain, which does more than any organ, reveals least of all. The 3-lb. lump of wrinkled tissue--with no moving parts, no joints or valves--not only serves as the motherboard for all the body's other systems but also is the seat of your mind, your thoughts, your sense that you exist at all. You have a liver; you have your limbs. You are your brain.
The struggle of the mind to fathom the brain it inhabits is the most circular kind of search--the cognitive equivalent of M.C. Escher's lithograph of two hands drawing one another. But that has not stopped us from trying. In the 19th century, German physician Franz Joseph Gall claimed to have licked the problem with his system of phrenology, which divided the brain into dozens of personality organs to which the skull was said to conform. Learn to read those bony bumps, and you could know the mind within. The artificial--and, ultimately, racist--field of craniometry made similar claims, relying on the overall size and shape of the skull to try to determine intelligence and moral capacity.
Modern scientists have done a far better job of things, dividing the brain into multiple, discrete regions with satisfyingly technical names--hypothalamus, caudate nucleus, neocortex--and mapping particular functions to particular sites. Here lives abstract thought; here lives creativity; here is emotion; here is speech. But what about here and here and here and here--all the countless places and ways the brain continues to baffle us? Here still be dragons.
Slowly, that is changing. As 21st century science and technology open the brain to us as never before, accepted truths are becoming less true. The brain, we're finding, is indeed a bordered organ, subdivided into zones and functions. But the lines are blurrier than we ever imagined. Lose your vision, and the lobe that processed light may repurpose itself for other senses. Suffer a stroke in the area that controls your right arm, and another area may take over at least some of the job.
Specialized neurons are being found that allow us to mirror the behavior of people around us, helping us learn such primal skills as walking and eating as well as how to become social, ethical beings. The mystery of memory is being teased apart, exposing the way we store facts and experiences in addition to the emotional flavors associated with them. Magnetic resonance imaging is probing the brain as it operates, essentially--if crudely--reading our minds, and raising all the attendant ethical questions.
Finally and most elusively, we are learning something about consciousness itself--the ghost in the neural machine that gives you the sense of being in the moment, peering out at the world from the control room behind your eyes. If we can identify that cognitive kernel, can we one day endow a machine with it? But by isolating such a thing, do we in some way annihilate it too?
Human beings have always been brash enough to ask such questions but lacked the necessary gifts to answer them. At last, we are acquiring that ability. What we can't yet know is whether we will wisely use the remarkable things we're slowly learning.
Friday, Jan. 19, 2007