Phantoms in the Brain – V.S. Ramachandran, Sandra Blakeslee

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Chapter 3
Chasing the Phantom

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When I gave him the mirror to try that same afternoon, he was able to open his phantom hand instantly. The spasms were eliminated and so too was the “digging sensation” of nails biting into his palm. This is a mind−boggling observation if you think about it. Here is a man with no hand and no fingernails. How does one get nonexistent nails digging into a nonexistent palm, resulting in severe pain? Why would a mirror eliminate the phantom spasm?

Consider what happens in your brain when motor commands are sent from the premotor and motor cortex to make a fist. Once your hand is clenched, feedback signals from muscles and joints of your hand are sent back through the spinal cord to your brain saying, Slow down, enough. Any more pressure and it could hurt. This proprioceptive feedback applies brakes, automatically, with astonishing speed and precision.If the limb is missing, however, this damping feedback is not possible. The brain therefore keeps sending the message, Clench more, clench more. Motor output is amplified even further (to a level that far exceeds anything you or I would ever experience) and the overflow or “sense of effort” may itself be experienced as pain. The mirror may work by providing visual feedback to unclench the hand, so that the clenching spasm is abolished.

But why the sensation of digging fingernails? Just think of the numerous occasions when you actually clenched your fist and felt your nails biting in your palm. These occasions must have created a memory link in your brain (psychologists call it a Hebbian link) between the motor command to clench and the unmistakable sensation of “nails digging,” so you can readily summon up this image in your mind. Yet even though you can imagine the image quite vividly, you don’t actually feel the sensation and say, “Ouch, that hurts.” Why not?

The reason, I believe, is that you have a real palm and the skin on the palm says there is no pain. You can imagine it but you don’t feel it because you have a normal hand sending real feedback and in the clash between reality and illusion, reality usually wins. But the amputee doesn’t have a palm. There are no countermanding signals from the palm to forbid the emergence of these stored pain memories. When Robert imagines that his nails are digging into his hand, he doesn’t get contradictory signals from his skin surface saying, “Robert, you fool, there’s no pain down here.”

Indeed, if the motor commands themselves are linked to the sense of nail digging, it’s conceivable that the amplification of these commands leads to a corresponding amplification of the associated pain signals. This might explain why the pain is so brutal. The implications are radical. Even fleeting sensory associations such as the one between clenching our hands and digging our fingernails into our palms are laid down as permanent traces in the brain and are only unmasked under certain circumstances—experienced in this case as phantom limb pain. Moreover, these ideas imply that pain is an opinion on the organism’s state of health rather than a mere reflexive response to an injury. There is no direct hotline from pain receptors to “pain centers” in the brain. On the contrary, there is so much interaction between different brain centers, like those concerned with vision and touch, that even the mere visual appearance of an opening fist can actually feed all the way back into the patient’s motor and touch pathways, allowing him to feel the fist opening, thereby killing an illusory pain in a nonexistent hand.
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Both these illusions are much more than amusing party tricks to try on your friends. The idea that you can actually project your sensations to external objects is radical and reminds me of phenomena such as out−of−body experiences or even voodoo (prick the doll and “feel” the pain). But how can we be sure the student volunteer isn’t just being metaphorical when she says “I feel my nose out there” or “The table feels like my own hand.” After all, I often have the experience of “feeling” that my car is part of my extended body image, so much so that I become infuriated if someone makes a small dent on it. But would I want to argue from this that the car had become part of my body?

These are not easy questions to tackle, but to find out whether the students really identified with the table surface, we devised a simple experiment that takes advantage of what is called the galvanic skin response or GSR. If I hit you with a hammer or hold a heavy rock over your foot and threaten to drop it, your brain’s visual areas will dispatch messages to your limbic system (the emotional center) to prepare your body to take emergency measures (basically telling you to run from danger). Your heart starts pumping more blood and you begin sweating to dissipate heat. This alarm response can be monitored by measuring the changes in skin resistance—the so−called GSR—caused by the sweat. If you look at a pig, a newspaper or a pen there is no GSR, but if you look at something evocative—a Mapplethorpe photo, a Playboy centerfold or a heavy rock teetering above your foot—you will register a huge GSR.

So I hooked up the student volunteers to a GSR device while they stared at the table. I then stroked the hidden hand and the table surface simultaneously for several seconds until the student started experiencing the table as his own hand. Next I bashed the table surface with a hammer as the student watched. Instantly, there was a huge change in GSR as if I had smashed the student’s own fingers. (When I tried the control experiment of stroking the table and hand out of sync, the subject did not experience the illusion and there was no GSR response.) It was as though the table had now become coupled to the student’s own limbic system and been assimilated into his body image, so much so that pain and threat to the dummy are felt as threats to his own body, as shown by the GSR. If this argument is correct, then perhaps it’s not all that silly to ask whether you identify with your car. Just punch it to see whether your GSR changes. Indeed the technique may give us a handle on elusive psychological phenomena such as the empathy and love that you feel for a child or spouse. If you are deeply in love with someone, is it possible that you have actually become part of that person? Perhaps your souls—and not merely your bodies—have become intertwined.

Now just think about what all this means. For your entire life, you’ve been walking around assuming that your “self is anchored to a single body that remains stable and permanent at least until death. Indeed, the “loyalty” of your self to your own body is so axiomatic that you never even pause to think about it, let alone question it. Yet these experiments suggest the exact opposite—that your body image, despite all its appearance of durability, is an entirely transitory internal construct that can be profoundly modified with just a few simple tricks. It is merely a shell that you’ve temporarily created for successfully passing on your genes to your offspring.
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Chapter 5
The Secret Life of James Thurber

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But if this argument is correct—if the early visual areas are activated each time you imagine something—then why don’t you and I hallucinate all the time or at least occasionally confuse our internally generated images with real objects? Why don’t you see a monkey in the chair when you simply think of one? The reason is that even if you close your eyes, cells in your retina and in early sensory pathways are constantly active—producing a flat, baseline signal. This baseline signal informs your higher visual centers that there is no object (monkey) hitting the retina— thereby vetoing the activity evoked by top−down imagery. But if the early visual pathways are damaged, this baseline signal is removed and so you hallucinate.

It makes good evolutionary sense that even though your internal images can be very realistic, they can never actually substitute for the real thing. You cannot, as Shakespeare said, “cloy the hungry edge of appetite by bare imagination of a feast.” A good thing, too, because if you could satisfy your hunger by thinking about a feast, you wouldn’t bother to eat and would quickly become extinct. Likewise, any creature that could imagine orgasms is unlikely to transmit its genes to the next generation. (Of course, we can do so to a limited extent as when our hearts pound when imagining an amorous encounter—the basis of what is sometimes called visualization therapy.)

Additional support for this interaction between top−down imagery and bottom−up sensory signals in perception comes from what we saw in phantom limb patients who have vivid impressions of clenching their nonexistent fingers and digging imaginary fingernails into their phantom palms, generating unbearable pain. Why do these patients actually feel clenching, “nails digging” and pain, whereas you or I can imagine the same finger position but feel nothing? The answer is that you and I have real input coming in from our hands telling us that there is no pain, even though we have memory traces in our brain linking the act of clenching with nails digging (especially if you don’t often cut your nails). But in an amputee, these fleeting associations and preexisting pain memories can now emerge without contradiction from ongoing sensory input. The same sort of thing might be happening in Charles Bonnet syndrome. But why did Nancy always see cartoons in her scotoma? One possibility is that in her brain the feedback comes mainly from the what pathway in the temporal lobe, which, you will recall, has cells specialized for color and shapes but not for motion and depth, which are handled by the how pathway. Therefore, her scotoma is filled with images that lack depth and motion, having only outlines and shapes, as do cartoons.

If I’m right, all these bizarre visual hallucinations are simply an exaggerated version of the processes that occur in your brain and mine every time we let our imagination run free. Somewhere in the confused welter of interconnecting forward and backward pathways is the interface between vision and imagination We don’t have clear ideas yet about where this interface is or how it works (or even whether there is a single interface), but these patients provide some tantalizing clues about what might be going on. The evidence from them suggests that what we call perception is really the end result of a dynamic interplay between sensory signals and high−level stored information about visual images from the past. Each time any one of us encounters an object, the visual system begins a constant questioning process. Fragmentary evidence comes in and the higher centers say, “Hmmmmm, maybe this is an animal.” Our brains then pose a series of visual questions: as in a twenty−questions game. Is it a mammal? A cat? What kind of cat? Tame? Wild? Big? Small? Black or white or tabby? The higher visual centers then project partial “best fit” answers back to lower visual areas including the primary visual cortex. In this manner, the impoverished image is progressively worked on and refined (with bits “filled in,” when appropriate). I think that these massive feed forward and feedback projections are in the business of conducting successive iterations that enable us to home in on the closest approximation to the truth.  To overstate the argument deliberately, perhaps we are hallucinating all the time and what we call perception is arrived at by simply determining which hallucination best conforms to the current sensory input. But if, as happens in Charles Bonnet syndrome, the brain does not receive confirming visual stimuli, it is free simply to make up its own reality. And, as James Thurber was well aware, there is apparently no limit to its creativity.

Chapter 6
Through the Looking Glass

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When you glance at any visual scene, the image excites receptors in your retina and sets in motion a complex cascade of events that culminate in your perception of the world. As we noted in earlier chapters, the message from the eye is first mapped onto an area in the back of brain called the primary visual cortex. From there it is relayed along two pathways, the how pathway to the parietal lobe and the what pathway to the temporal lobe (see Figure 4.5, Chapter 4). The temporal lobes are concerned with recognizing and naming individual objects and responding to them with the appropriate emotions. The parietal lobes, on the other hand, are concerned with discerning the spatial layout of the external world, allowing you to navigate through space, reach out for objects, dodge missiles and otherwise know where you are. This division of labor between temporal and parietal lobes can explain almost all of the peculiar constellation of symptoms one sees in neglect patients in whom one parietal lobe—especially the right—is damaged, as is the case with Ellen. If you let her wander around by herself, she will not pay attention to the left side of space and anything that happens in it. She will even bump into objects on her left side or stub her left toe on a raised pavement. (I’ll later explain why this doesn’t happen with left parietal damage.) However, because Ellen’s temporal lobes are still intact, she has no difficulty recognizing objects and events as long as her attention is drawn to them.

But “attention” is a loaded word, and we know even less about it than we do about neglect. So the statement that the neglect arises from a “failure to pay attention” doesn’t really tell us very much unless we have a clear notion of what the underlying neural mechanisms might be. (It’s a bit like saying that illness results from a failure of health.) In particular, one would like to know how a normal person—you or I—is able to attend selectively to a single sensory input, whether you are trying to listen to a single voice amid the background din of voices at a cocktail party or just trying to spot a familiar face in a baseball stadium. Why do we have this vivid sense of having an internal searchlight, one that we can direct at different objects and events around us?

We now know that even so basic a skill as attention requires the participation of many far−flung regions of the brain. We’ve already talked about the visual, auditory and somatosensory systems, but other special brain regions carry out equally important tasks. The reticular activating system—a tangle of neurons in the brain stem that projects widely to vast regions of the brain-activates the entire cerebral cortex, leading to arousal and wakefulness, or-when needed-a small portion of the cortex, leading to selective attention. The limbic system is concerned with emotional behavior and evaluation of the emotional significance and potential value of events in the external world. The frontal lobes are concerned with more abstract processes like judgment, foresight and planning. All of these areas are interconnected in a positive feedback loop—a recursive, echolike reverberation—that takes a stimulus from the outside world, extracts its salient features and then bounces it from region to region, before eventually figuring out what it is and how to respond to it. Should I fight, flee, eat or kiss? The simultaneous deployment of all these mechanisms culminates in perception.

When a large, threatening stimulus—say, an image of a menacing figure, perhaps a mugger looming toward me on the street in Boston— first comes into my brain, I haven’t the slightest idea of what it is. Before I can determine, aha, perhaps that’s a dangerous person, the visual information is evaluated by both the frontal lobes and the limbic system for relevance and sent on to a small portion of the parietal cortex, which, in conjunction with appropriate neural connections in the reticular formation, enables me to direct my attention to the looming figure. It forces my brain to swivel my eyeballs toward something important out there in the visual scene, pay selective attention to it and say, “Aha!”

But imagine what would happen if any part of this positive feedback loop were interrupted so that the whole process was compromised. You would then no longer notice what was happening on one side of the world. You would be a neglect patient.

But we still have to explain why neglect occurs primarily after injury to the right parietal lobe and not to the left. Why the asymmetry? Though the real reason continues to elude us, Marcel Mesulam of Harvard University has proposed an ingenious theory. We know that the left hemisphere is specialized for many aspects of language and the right hemisphere for emotions and “global” or holistic aspects of sensory processing. But Mesulam suggests there is another fundamental difference. Given its role in holistic aspects of vision, the right hemisphere has a broad “searchlight” of attention that encompasses both the entire left and entire right visual fields. The left hemisphere, on the other hand, has a much smaller searchlight, which is confined entirely to the right side of the world (perhaps because it is so busy with other things, such as language). As a result of this rather odd arrangement, if the left hemisphere is damaged, it loses its searchlight, but the right can compensate because it casts a searchlight on the entire world. When the right hemisphere is damaged, on the other hand, the global searchlight is gone but the left hemisphere cannot fully compensate for the loss because its searchlight is confined only to the right side. This would explain why neglect is only seen in patients whose right hemisphere is damaged.
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Normal adults rarely confuse a mirror reflection for a real object. When you spot a car fast approaching you in your rearview mirror, you don’t jam on your brakes. You accelerate forward even though it appears that the image of the car is approaching rapidly from the front. Likewise, if a burglar opened the door behind you as you were shaving in the bathroom, you’d spin around to confront him—not attack the reflection in the mirror.Some part of your brain must be making the needed correction: The real object is behind me even though the image is in front of me.

But like Alice in Wonderland, patients like Ellen and Steve seem to inhabit a strange no−man’s−land between illusion and reality—a “warped world,” as Steve called it, and there is no easy way to predict how they will react to a mirror. Even though all of us, neglect patients and normal people alike, are familiar with mirrors and take them for granted, there is something inherently surrealistic about mirror images. The optics are simple enough, but no one has any inkling of what brain mechanisms are activated when we look at a mirror reflection, of what brain processes are involved in our special ability to comprehend the paradoxical juxtaposition of a real object and its optical “twin.” Given the right parietal lobe’s important role in dealing with spatial relationships and “holistic” aspects of vision, would a neglect patient have special problems dealing with mirror reflections?
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After a half−hour break, we returned to the lab to try out the mirror. She sat in her wheelchair, fluffing up her hair with her good hand, and smiled sweetly. I stood on her right holding a mirror on my chest so that when Ellen faced straight forward in the chair, the mirror was parallel to the right arm of the wheelchair (and her profile) and about two feet away from her nose. I then asked her to turn her head about sixty degrees and look into the mirror.

From this vantage point Ellen can clearly see the neglected side of the world reflected in the mirror. She is looking to her right, into her good side, so to speak, and she knows perfectly well what a mirror is, so she knows that it is reflecting objects on her left side. Since the information about the left side of the world is now coming from the right side—the nonneglected side—would the mirror help her “overcome” her neglect so that she correctly reached for the objects on the left, just as a normal person might? Or would she say to herself, “Oops, that object is really in my neglected field, so let me ignore it.” The answer, as so often happens in science, was that she did neither. In fact, she did something completely outlandish.

Ellen looked in the mirror and blinked, curious about what we were up to. It ought to have been obvious to her that it was a mirror since it had a wooden frame and dust on its surface, but to be absolutely sure, I asked, “What is this I am holding?” (Remember I was behind the mirror, holding it.)

She replied without hesitating, “A mirror.”

I asked her to describe her eyeglasses, lipstick and clothing while looking straight into the mirror. She did so with no trouble. On receiving a cue, one of my students standing on Ellen’s left side held out a pen so that it was well within the reach of her good right hand but entirely within the neglected left visual field. (This turned out to be about eight inches below and to the left of her nose.) Ellen could see my student’s arm as well as the pen clearly in the mirror, as there was no intent to deceive her about the presence of a mirror.

“Do you see the pen?”

“Yes.”

“Okay, please reach out and grab it and write your name on this pad of paper I’ve placed in your lap.”

Imagine my astonishment when Ellen lifted her right hand and without hesitation went straight for the mirror and began banging on it repeatedly. She literally clawed at it for about twenty seconds and said, obviously frustrated, “It’s not in my reach.”

When I repeated the same process ten minutes later, she said, “It’s behind the mirror,” and reached around and began groping with my belt buckle.

A little later she even tried peeking over the edge of the mirror to look for the pen.

So Ellen was behaving as though the reflection were a real object that she could reach out and grab. In my fifteen−year career, I’d never seen anything like this—a perfectly intelligent, levelheaded adult making the absurd blunder of thinking that an object was actually inside the mirror.

We wanted to make sure that Ellen’s behavior did not arise from some clumsiness of her arm movements or a failure to understand what mirrors are. So we simply tried placing the mirror at arm’s length in front of her, just like a bathroom mirror at home. This time the pen appeared just behind and above her right shoulder (but just outside her visual field). She saw it in the mirror and her hand went straight back behind her to grab it. So her failure in the earlier task could not be explained by claiming that she was disoriented, clumsy or confused as a result of her stroke.

We decided to give a name to Ellen’s condition—”mirror agnosia” or “the looking glass syndrome” in honor of Lewis Carroll. Indeed, Lewis Carroll is known to have suffered from migraine attacks caused by arterial spasms. If they affected his right parietal lobe, he may have suffered momentary confusion with mirrors that might not only have inspired him to write Through the Looking Glass but may help explain his general obsession with mirrors, mirror writing and left−right reversal. One wonders whether Leonardo da Vinci’s preoccupation with left−right reversed writing had a similar origin.
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Therapy aside, the scientist in me is equally intrigued by mirror agnosia—the patient’s failure to reach correctly for the real object. Even my two−year−old son, when shown candy only visible in the mirror, giggled, turned around and snatched the sweet. Yet the much older and wiser Ellen could not do this.

I can think of at least two interpretations of why she might lack this ability. First, it’s possible that the syndrome is caused by her neglect. It’s as though the patient was saying to herself, unconsciously, “Since the reflection is in the mirror, the object must be on my left. But the left does not exist on my planet—therefore, the object must be inside the mirror.” However absurd this interpretation may seem to us with our intact brains, it’s the only one that would make any sense to Ellen, given her “reality.”

Second, the looking glass syndrome may not be a direct consequence of neglect, even though it is usually accompanied by neglect. We know that when the right parietal lobe is damaged, patients have all kinds of difficulties with spatial tasks, and the looking glass syndrome may simply be an especially florid manifestation of such deficits. Responding correctly to a mirror image requires you simultaneously to hold in your mind the reflection as well as the object that is producing it and then perform the required mental gymnastics to locate correctly the object that produced the reflection. This very subtle ability may be compromised by lesions in the right parietal lobe, given the important role of that structure in dealing with spatial attributes of the world. If so, mirror agnosia might provide a new bedside test for detecting right parietal lesions. In an age of escalating costs of brain imaging, any simple new test would be a useful addition to the neurologist’s diagnostic kit.

The strangest aspect of the looking glass syndrome, however, is listening to patients’ reactions.

“Doctor, why can’t I reach the pen?”

“The darn mirror is in the way.”

“The pen is inside the mirror and I can’t reach it!”

“Ellen, I want you to grab the real object, not the reflection. Where is the real object?” She replied, “The real object is out there behind the mirror, doctor.”

It’s astonishing that the mere confrontation with a mirror flips these patients into the twilight zone so that they are unable—or reluctant— to draw the simple logical inference that since the reflection is on the right, the object producing it must be on the left. It’s as though for these patients even the laws of optics have changed, at least for this small corner of their universe. We ordinarily think of our intellect and “high−level” knowledge—such as laws concerning geometrical optics—as being immune to the vagaries of sensory input. But these patients teach us that this is not always true. Indeed, for them it’s the other way around. Not only is their sensory world warped, but their knowledge base is twisted to accommodate the strange new world they inhabit. Their attention deficits seem to permeate their whole outlook, rendering them unable to tell whether a mirror reflection is a real object or not, even though they can carry on normal conversations on other topics—politics, sports or chess—just as well as you or I.  Asking these patients what is the “true location” of the object they see in the mirror is like asking a normal person what is north of the North Pole. Or whether an irrational number (like the square root of 2 or pi with a never−ending string of decimals) really exists or not. This raises profound philosophical questions about how sure we can be that our own grasp on reality is all that secure. An alien four−dimensional creature watching us from his four−dimensional world might regard our behavior to be just as perverse, inept and absurdly comical as we regard the bumblings of neglect patients trapped in their strange looking−glass world.

Chapter 7
The Sound of One Hand Clapping

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Watching these patients is like observing human nature through a magnifying lens; I’m reminded of all aspects of human folly and of how prone to self−deception we all are. For here, embodied in one elderly woman in a wheelchair, is a comically exaggerated version of all those psychological defense mechanisms that Sigmund and Anna Freud talked about at the beginning of the twentieth century—mechanisms used by you, me and everyone else when we are confronted with disturbing facts about ourselves. Freud claimed that our minds use these various psychological tricks to “defend the ego.” His ideas have such intuitive appeal that many of the words he used have infiltrated popular parlance, although no one thinks of them as science because he never did any experiments. (We shall return to Freud later in this chapter to see how anosognosia may give us an experimental handle on these elusive aspects of the mind.)

In the most extreme cases, a patient will not only deny that the arm (or leg) is paralyzed, but assert that the arm lying in the bed next to him, his own paralyzed arm, doesn’t belong to him! There’s an unbridled willingness to accept absurd ideas.
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Anosognosia is an extraordinary syndrome about which almost nothing is known. The patient is obviously sane in most respects yet claims to see her lifeless limb springing into action—clapping or touching my nose—and fails to realize the absurdity of it all. What causes this curious disorder? Not surprisingly, there have been dozens of theories to explain anosognosia. Most can be classified into two main categories. One is a Freudian view, that the patient simply doesn’t want to confront the unpleasantness of his or her paralysis.

The second is a neurological view, that denial is a direct consequence of the neglect syndrome, discussed in the previous chapter—the general indifference to everything on the left side of the world. Both categories of explanation have many problems, but they also contain nuggets of insight that we can use to build a new theory of denial.

One problem with the Freudian view is that it doesn’t explain the difference in magnitude of psychological defense mechanisms between patients with anosognosia and what is seen in normal people—why they are generally subtle in you and me and wildly exaggerated in denial patients. For example, if I were to fracture my left arm and damage certain nerves and you asked me whether I could beat you in a game of tennis, I might tend to play down my injury a little, asserting, “Oh, yes, I can beat you. My arm is getting much better now, you know.” But I certainly wouldn’t take a bet that I could arm wrestle you. Or if my arm were completely paralyzed, hanging limp at my side, I would not say, “Oh, I can see it touching your nose” or “It belongs to my brother.”

The second problem with the Freudian view is that it doesn’t explain the asymmetry of this syndrome. The kind of denial seen in Mrs. Dodds and others is almost always associated with damage to the right hemisphere of the brain, resulting in paralysis of the body’s left side. When people suffer damage to the left brain hemisphere, with paralysis on the body’s right side, they almost never experience denial. Why not? They are as disabled and frustrated as people with right hemisphere damage, and presumably there is just as much “need” for psychological defense, but in fact they are not only aware of the paralysis, but constantly talk about it. Such asymmetry implies that we must look not to psychology but to neurology for an answer, particularly in the details of how the brain’s two hemispheres are specialized for different tasks. Indeed, the syndrome seems to straddle the border between the two disciplines, one reason it is so fascinating.

Neurological theories of denial reject the Freudian view completely. They argue instead that denial is a direct consequence of neglect, which also occurs after right hemisphere damage and leaves patients profoundly indifferent to everything that goes on within the left side of the world, including the left side of their own bodies. Perhaps the patient with anosognosia simply doesn’t notice that her left arm is not moving in response to her commands, and hence the delusion.

I find two main problems with this approach. One is that neglect and denial can occur independently—some patients with neglect do not experience denial and vice versa. Second, neglect does not account for why denial usually persists even when the patient’s attention is drawn to the paralysis. For instance, if I were to force a patient to turn his head and focus on his left arm, to demonstrate to him that it’s not obeying his command, he may adamantly continue to deny that it’s paralyzed—or even that it belongs to him. It is this vehemence of the denial—not a mere indifference to paralysis—that cries out for an explanation. Indeed, the reason anosognosia is so puzzling is that we have come to regard the “intellect” as primarily propositional in character-that is, certain conclusions follow incontrovertibly from certain premises—and one ordinarily expects propositional logic to be internally consistent. To listen to a patient deny ownership of her arm and yet, in the same breath, admit that it is attached to her shoulder is one of the most perplexing phenomena that one can encounter as a neurologist.

So neither the Freudian view nor the neglect theory provides an adequate explanation for the spectrum of deficits that one sees in anosog−nosia. The correct way to approach the problem, I realized, is to ask two questions: First, why do normal people engage in all these psychological defense mechanisms? Second, why are the same mechanisms so exaggerated in these patients? Psychological defenses in normal people are especially puzzling because at first glance they seem detrimental to survival. Why would it enhance my survival to cling tenaciously to false beliefs about myself and the world? If I were a puny weakling who believed that I was as strong as Hercules, I’d soon get into serious trouble with the “alpha male” in my social group—my chairman, the president of my company or even my next−door neighbor. But, as Charles Darwin pointed out, if one sees something apparently maladaptive in biology, then look more deeply, because there is often a hidden agenda.

The key to the whole puzzle, I suggest, lies in the division of labor between our two cerebral hemispheres and in our need to create a sense of coherence and continuity in our lives. Most people are familiar with the fact that the human brain consists of two mirror image halves—like the two halves of a walnut—with each half, or cerebral hemisphere, controlling movements on the opposite side of the body. A century of clinical neurology has shown clearly that the two hemispheres are specialized for different mental capacities and that the most striking asymmetry involves language. The left hemisphere is specialized not only for the actual production of speech sounds but also for the imposition of syntactic structure on speech and for much of what is called semantics—comprehension of meaning. The right hemisphere, on the other hand, doesn’t govern spoken words but seems to be concerned with more subtle aspects of language such as nuances of metaphor, allegory and ambiguity—skills that are inadequately emphasized in our elementary schools but that are vital for the advance of civilizations through poetry, myth and drama. We tend to call the left hemisphere the major or “dominant” hemisphere because it, like a chauvinist, does all the talking (and maybe much of the internal thinking as well), claiming to be the repository of humanity’s highest attribute, language. Unfortunately, the mute right hemisphere can do nothing to protest.

Other obvious specializations involve vision and emotion. The right hemisphere is concerned with holistic aspects of vision such as seeing the forest for the trees, reading facial expressions and responding with the appropriate emotion to evocative situations. Consequently, after right hemisphere strokes, patients tend to be blissfully unconcerned about their predicament, even mildly euphoric, because without the “emotional right hemisphere” they simply don’t comprehend the magnitude of their loss. (This is true even of those patients who are aware of their paralysis.)

In addition to these obvious divisions of labor, I want to suggest an even more fundamental difference between the cognitive styles of the two hemispheres, one that not only helps explain the amplified defense mechanisms of anosognosia but may also help account for the more mundane forms of denial that people use in daily life—such as when an alcoholic refuses to acknowledge his drinking problem or when you deny your forbidden attraction to a married colleague.

At any given moment in our waking lives, our brains are flooded with a bewildering array of sensory inputs, all of which must be incorporated into a coherent perspective that’s based on what stored memories already tell us is true about ourselves and the world. In order to generate coherent actions, the brain must have some way of sifting through this superabundance of detail and of ordering it into a stable and internally consistent “belief system”—a story that makes sense of the available evidence. Each time a new item of information comes in we fold it seamlessly into our preexisting worldview. I suggest that this is mainly done by the left hemisphere.

But now suppose something comes along that does not quite fit the plot. What do you do? One option is to tear up the entire script and start from scratch: completely revise your story to create a new model about the world and about yourself. The problem is that if you did this for every little piece of threatening information, your behavior would soon become chaotic and unstable; you would go mad.

What your left hemisphere does instead is either ignore the anomaly completely or distort it to squeeze it into your preexisting framework, to preserve stability. And this, I suggest, is the essential rationale behind all the so−called Freudian defenses—the denials, repressions, confabulations and other forms of self−delusion that govern our daily lives. Far from being maladaptive, such everyday defense mechanisms prevent the brain from being hounded into directionless indecision by the “combinatorial explosion” of possible stories that might be written from the material available to the senses. The penalty, of course, is that you are “lying” to yourself, but it’s a small price to pay for the coherence and stability conferred on the system as a whole.

Imagine, for example, a military general about to wage war on the enemy. It is late at night and he is in the war room planning strategies for the next day. Scouts keep coming into the room to give him information about the lay of the land, terrain, light level and so forth. They also tell him that the enemy has five hundred tanks and that he has six hundred tanks, a fact that prompts the general to decide to wage war. He positions all of his troops in strategic locations and decides to launch battle exactly at 6:00 a.m. with sunrise.

Imagine further that at 5:55 A.M. one little scout comes running into the war room and says, “General! I have bad news.” With minutes to go until battle, the general asks, “What is that?” and the scout replies, “I just looked through binoculars and saw that the enemy has seven hundred tanks, not five hundred!”

What does the general—the left hemisphere—do? Time is of the essence and he simply can’t afford the luxury of revising all his battle plans. So he orders the scout to shut up and tell no one about what he saw. Denial! Indeed, he may even shoot the scout and hide the report in a drawer labeled “top secret” (repression). In doing so, he relies on the high probability that the majority opinion—the previous information by all the scouts—was correct and that this single new item of information coming from one source is probably wrong. So the general sticks to his original position. Not only that, but for fear of mutiny, he might order the scout actually to lie to the other generals and tell them that he only saw five hundred tanks (confabulation). The purpose of all of this is to impose stability on behavior and to prevent vacillation because indecisiveness doesn’t serve any purpose. Any decision, so long as it is probably correct, is better than no decision at all. A perpetually fickle general will never win a war!

In this analogy, the general is the left hemisphere (Freud’s “ego,” perhaps?), and his behavior is analogous to the kinds of denials and repressions you see in both healthy people and patients with anosognosia. But why are these defense mechanisms so grossly exaggerated in the patients? Enter the right hemisphere, which I like to call the Devil’s Advocate. To see how this works, we need to push the analogy a step further. Supposing the single scout comes running in, and instead of saying the enemy has more tanks, he declares, “General, I just looked through my telescope and the enemy has nuclear weapons.” The general would be very foolish indeed to adhere to his original plan. He must quickly formulate a new one, for if the scout were correct, the consequences would be devastating.

Thus the coping strategies of the two hemispheres are fundamentally different. The left hemisphere’s job is to create a belief system or model and to fold new experiences into that belief system. If confronted with some new information that doesn’t fit the model, it relies on Freudian defense mechanisms to deny, repress or confabulate—anything to preserve the status quo. The right hemisphere’s strategy, on the other hand, is to play “Devil’s Advocate,” to question the status quo and look for global inconsistencies. When the anomalous information reaches a certain threshold, the right hemisphere decides that it is time to force a complete revision of the entire model and start from scratch. The right hemisphere thus forces a “Kuhnian paradigm shift” in response to anomalies, whereas the left hemisphere always tries to cling tenaciously to the way things were.

Now consider what happens if the right hemisphere is damaged. The left hemisphere is then given free rein to pursue its denials, confabulations and other strategies, as it normally does. It says, “I am Mrs. Dodds, a person with two normal arms that I have commanded to move.” But her brain is insensitive to the contrary visual feedback that would ordinarily tell her that her arm is paralyzed and that she’s in a wheelchair. Thus Mrs. Dodds is caught in a delusional cul−de−sac. She cannot revise her model of reality because her right hemisphere, with its mechanisms for detecting discrepancies, is out of order. And in the absence of the counterbalance or “reality check” provided by the right hemisphere, there is literally no limit to how far she will wander along the delusional path. Patients will say, “Yes, I’m touching your nose, Dr. Ramachandran,” or “All of the medical students have been prodding me and that’s why I don’t want to move my arm.” Or even, “What is my brother’s hand doing in my bed, doctor?”

The idea that the right hemisphere is a left−wing revolutionary that generates paradigm shifts, whereas the left hemisphere is a die−hard conservative that clings to the status quo, is almost certainly a gross oversimplification, but, even if it turns out to be wrong, it does suggest new ways of doing experiments and goads us into asking novel questions about the denial syndrome. How deep is the denial? Does the patient really believe he’s not paralyzed? What if you were to confront patients directly: Could you then force them to admit the paralysis? Would they deny only their paralysis, or would they deny other aspects of their illness as well? Given that people often think of their car as part of their extended “body image”(especially here in California), what would happen if the front left fender of their car were damaged? Would they deny that? Anosognosia has been known for almost a century, yet there have been very few attempts to answer these questions. Any light we could shed on this strange syndrome would be clinically important, of course, because the patients’ indifference to their predicament not only is an impediment to rehabilitation of the weak arm or leg, but often leads them to unrealistic future goals. (For example, when I asked one man whether he could go back to his old occupation of repairing telephone lines—a job that requires two hands for climbing poles and splicing wires—he said, “Oh, yes, I don’t see a problem there.”) What I didn’t realize, though, when I began these experiments, was that they would take me right into the heart of human nature. For denial is something we do all our lives, whether we are temporarily ignoring the bills accumulating in our “to do” tray or defiantly denying the finality and humiliation of death.
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Freud bashing is a popular intellectual pastime these days (although he still has his fans in New York and London). But, as we have seen in this chapter, he did have some valuable insights into the human condition, and, when talking about psychological defenses, he was right on target, although he had no idea why they evolved or what neural mechanisms might mediate them. A less well known, but equally interesting idea put forward by Freud was his claim that he had discerned the single common denominator of all great scientific revolutions: Rather surprisingly, all of them humiliate or dethrone “man” as the central figure in the cosmos.

The first of these, he said, was the Copernican revolution, in which a geocentric or earth−centered view of the universe was replaced with the idea that earth is just a speck of dust in the cosmos. The second was the Darwinian revolution, which holds that we are puny, hairless neotenous apes that accidentally evolved certain characteristics that have made us successful, at least temporarily.

The third great scientific revolution, he claimed (modestly), was his own discovery of the unconscious and the corollary notion that the human sense of “being in charge” is illusory. He claimed that everything we do in life is governed by a cauldron of unconscious emotions, drives and motives and that what we call consciousness is just the tip of the iceberg, an elaborate post hoc rationalization of all our actions.

I believe Freud correctly identified the common denominator of great scientific revolutions. But he doesn’t explain why this is so—why would human beings actually enjoy being “humiliated” or dethroned? What do they get in return for accepting the new worldview that belittles humankind?

Here we can turn things around and provide a Freudian interpretation of why cosmology, evolution and brain science are so appealing, not just to specialists but to everyone. Unlike other animals, humans are acutely aware of their own mortality and are terrified of death. But the study of cosmology gives us a sense of timelessness, of being part of something much larger. The fact that your own personal life is finite is less frightening when you know you are part of an evolving universe—an ever−unfolding drama. This is probably the closest a scientist can come to having a religious experience.

The same goes for the study of evolution, for it gives you a sense of time and place, allowing you to see yourself as part of a great journey. And likewise for the brain sciences. In this revolution, we have given up the idea that there is a soul separate from our minds and bodies. Far from being terrifying, this idea is very liberating. If you think you’re something special in this world, engaging in a lofty inspection of the cosmos from a unique vantage point, your annihilation becomes unacceptable. But if you’re really part of the great cosmic dance of Shiva, rather than a mere spectator, then your inevitable death should be seen as a joyous reunion with nature rather than as a tragedy.

Brahman is all. From Brahman come appearances, sensations, desires, deeds. But all these are merely name and form. To know Brahman one must experience the identity between him and the Self, or Brahman dwelling within the lotus of the heart. Only by so doing can man escape from sorrow and death and become one with the subtle essence beyond all knowledge.
—Upanishads, 500 b.c.

Chapter 8
“The Unbearable Lightness of Being”

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Arthur was suffering from Capgras’ delusion, one of the rarest and most colorful syndromes in neurology. The patient, who is often mentally quite lucid, comes to regard close acquaintances—usually his parents, children, spouse or siblings—as impostors. As Arthur said over and over, “That man looks identical to my father but he really isn’t my father. That woman who claims to be my mother? She’s lying. She looks just like my mom but it isn’t her.” Although such bizarre delusions can crop up in psychotic states, over a third of the documented cases of Capgras’ syndrome have occurred in conjunction with traumatic brain lesions, like the head injury that Arthur suffered in his automobile accident. This suggests to me that the syndrome has an organic basis. But because a majority of Capgras’ patients appear to develop this delusion “spontaneously,” they are usually dispatched to psychiatrists, who tend to favor a Freudian explanation of the disorder.
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A better approach for studying Capgras’ syndrome involves taking a closer look at neuroanatomy, specifically at pathways concerned with visual recognition and emotions in the brain. Recall that the temporal lobes contain regions that specialize in face and object recognition (the what pathway described in Chapter 4). We know this because when specific portions of the what pathway are damaged, patients lose the ability to recognize faces, even those of close friends and relatives—as immortalized by Oliver Sacks in his book The Man Who Mistook His Wife for a Hat. In a normal brain, these face recognition areas (found on both sides of the brain) relay information to the limbic system, found deep in the middle of the brain, which then helps generate emotional responses to particular faces (Figure 8.1). I may feel love when I see my mother’s face, anger when I see the face of a boss or a sexual rival or deliberate indifference upon seeing the visage of a friend who has betrayed me and has not yet earned my forgiveness. In each instance, when I look at the face,my temporal cortex recognizes the image—mother, boss, friend—and passes on the information to my amygdala (a gateway to the limbic system) to discern the emotional significance of that face. When this activation is then relayed to the rest of my limbic system, I start experiencing the nuances of emotion—love, anger, disappointment—appropriate to that particular face. The actual sequence of events is undoubtedly much more complex, but this caricature captures the gist of it.

After thinking about Arthur’s symptoms, it occurred to me that his strange behavior might have resulted from a disconnection between these two areas (one concerned with recognition and the other with emotions). Maybe Arthur’s face recognition pathway was still completely normal, and that was why he could identify everyone, including his mother and father, but the connections between this “face region” and his amygdala had been selectively damaged. If that were the case, Arthur would recognize his parents but would not experience any emotions when looking at their faces. He would not feel a “warm glow” when looking at his beloved mother, so when he sees her he says to himself, “If this is my mother, why doesn’t her presence make me feel like I’m with my mother?” Perhaps his only escape from this dilemma—the only sensible interpretation he could make given the peculiar disconnection between the two regions of his brain—is to assume that this woman merely resembles Mom. She must be an impostor.
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In the undergraduates, I found that there was a big jolt in the GSR in response to photos of their parents—as expected—but not to photos of strangers. In Arthur, on the other hand, the skin response was uniformly low. There was no increased response to his parents, or at times there would be a tiny blip on the screen after a long delay, as if he were doing a double take. This result provided direct proof that our theory was correct. Clearly Arthur was not responding emotionally to his parents, and this may be what led to the loss of his galvanic skin response. But how could we be sure that Arthur was even seeing the faces?
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We were now sure that Arthur had no problem in recognizing faces and telling them apart. But could his failure to produce a strong galvanic skin response to his parents be part of a more global disturbance in his emotional abilities? How could we be certain that the head injury had not also damaged his limbic system? Maybe he had no emotions, period. This seemed improbable because throughout the months I spent with Arthur, he showed a full range of human emotions. He laughed at my jokes and offered his own funny stories in return. He expressed frustration, fear and anger, and on rare occasions I saw him cry. Whatever the situation, his emotions were appropriate. Arthur’s problem, then, was neither his ability to recognize faces nor his ability to experience emotions; what was lost was his ability to link the two. So far so good, but why is the phenomenon specific to close relatives? Why not call the mailman an impostor, since his, too, is a familiar face? It may be that when any normal person (including Arthur, prior to his accident) encounters someone who is emotionally very close to him— a parent, spouse or sibling—he expects an emotional “glow,” a warm fuzzy feeling, to arise even though it may sometimes be experienced only very dimly. The absence of this glow is therefore surprising and Arthur’s only recourse then is to generate an absurd delusion—to rationalize it or to explain it away. On the other hand, when one sees the mailman, one doesn’t expect a warm glow and consequently there is no incentive for Arthur to generate a delusion to explain his lack of “warm fuzzy” response. A mailman is simply a mailman (unless the relationship has taken an amorous turn).

Although the most common delusion among Capgras’ patients is the assertion that a parent is an impostor, even more bizarre examples can be found in the older medical literature. Indeed, in a case on record the patient was convinced that his stepfather was a robot, proceeded to decapitate him and opened his skull to look for microchips. Perhaps in this patient, the dissociation from emotions was so extreme that he was forced into an even more absurd delusion than Arthur’s: that his stepfather was not even a human being, but was a mindless android!

About a year ago, when I gave a lecture on Arthur at the Veterans Administration Hospital in La Jolla, a neurology resident raised an astute objection to my theory. What about people who are born with a disease in which their amygdalas (the gateway to the limbic system) calcify and atrophy or those who lose their amygdalas (we each have two of them) completely in surgery or through an accident? Such people do exist, but they do not develop Capgras’ syndrome, even though their GSRs are flat to all emotionally evocative stimuli. Likewise, patients with damage to their frontal lobes (which receive and process information from the limbic system for making elaborate future plans) also often lack a GSR. Yet they, too, do not display Capgras’ syndrome. Why not? The answer may be that these patients experience a general blunting of all their emotional responses and therefore do not have a baseline for comparison. Like a purebred Vulcan or Data on Star Trek, one could legitimately argue, they don’t even know what an emotion is, whereas Capgras’ patients like Arthur enjoy a normal emotional life in all other respects. This idea teaches us an important principle about brain function, namely, that all our perceptions—indeed, maybe all aspects of our minds—are governed by comparisons and not by absolute values. This appears to be true whether you are talking about something as obvious as judging the brightness of print in a newspaper or something as subtle as detecting a blip in your internal emotional landscape. This is a far−reaching conclusion, and it also helps illustrate the power of our approach—indeed of the whole discipline that now goes by the name cognitive neuroscience. You can discover important general principles about how the brain works and begin to address deep philosophical questions by doing relatively simple experiments on the right patients. We started with a bizarre condition, proposed an outlandish theory, tested it in the lab and—in meeting objections to it—learned more about how the healthy brain actually works.

Taking these speculations even further, consider the extraordinary disorder called Cotard’s syndrome, in which a patient will assert that he is dead, claiming to smell rotten flesh or worms crawling all over his skin. Again, most people, even neurologists, would jump to the conclusion that the patient was insane. But that wouldn’t explain why the delusion takes this highly specific form. I would argue instead that Cotard’s is simply an exaggerated form of Capgras’ syndrome and probably has a similar origin. In Capgras’, the face recognition area alone is disconnected from the amygdala, whereas in Cotard’s perhaps all the sensory areas are disconnected from the limbic system, leading to a complete lack of emotional contact with the world. Here is another instance in which an outlandish brain disorder that most people regard as a psychiatric problem can be explained in terms of known brain circuitry. And once again, these ideas can be tested in the laboratory. I would predict that Cotard’s syndrome patients will have a complete loss of GSR for all external stimuli—not just faces—and this leaves them stranded on an island of emotional desolation, as close as anyone can come to experiencing death.

Arthur seemed to enjoy his visits to our laboratory. His parents were pleased that there was a logical explanation for his predicament, that he wasn’t just “crazy.” I never revealed the details to Arthur because I wasn’t sure how he’d react. Arthur’s father was an intelligent man, and at one point, when Arthur wasn’t around, he asked me, “If your theory is correct, doctor—if the information doesn’t get to his amygdala—then how do you explain how he has no problems recognizing us over the phone? Does that make sense to you?”

“Well,” I replied, “there is a separate pathway from the auditory cortex, the hearing area of the temporal lobes, to the amygdala. One possibility is that this hearing route has not been affected by the accident— only the visual centers have been disconnected from Arthur’s amygdala.” This conversation got me wondering about the other well−known functions of the amygdala and the visual centers that project to it. In particular, scientists recording cell responses in the amygdala found that, in addition to responding to facial expression and emotions, the cells also respond to the direction of eye gaze. For instance, one cell might fire if another person is looking directly at you, whereas a neighboring cell will fire only if that person’s gaze is averted by a fraction of an inch. Still other cells fire when the gaze is way off  to the left or the right. This phenomenon is not surprising, given the important role that gaze direction plays in primate social communications — the averted gaze of guilt, shame or embarrassment; the intense, direct gaze of a lover or the threatening stare of an enemy. We tend to forget that emotions, even though they are privately experienced, often involve interactions with other people and that one way we interact is through eye contact. Given the links among gaze direction, familiarity and emotions, I wondered whether Arthur’s ability to judge the direction of gaze, say, by looking at photographs of faces, would be impaired.

To find out, I prepared a series of images, each showing the same model looking either directly at the camera lens or at a point an inch or two to the right or left of the lens. Arthur’s task was simply to let us know whether the model was looking straight at him or not. Whereas you or I can detect tiny shifts in gaze with uncanny accuracy, Arthur was hopeless at the task. Only when the model’s eyes were looking way off to one side was he able to discern correctly that she wasn’t looking at him.
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As we continued testing Arthur, we noticed that he had certain other quirks and eccentricities. For instance, Arthur sometimes seemed to have a general problem with visual categories. All of us make mental taxonomies or groupings of events and objects: Ducks and geese are birds but rabbits are not. Our brains set up these categories even without formal education in zoology, presumably to facilitate memory storage and to enhance our ability to access these memories at a moment’s notice. Arthur, on the other hand, often made remarks hinting that he was confused about categories. For example, he had an almost obsessive preoccupation with Jews and Catholics, and he tended to label a disproportionate number of recently encountered people as Jews.

This propensity reminded me of another rare syndrome called Fregoli, in which a patient keeps seeing the same person everywhere. In walking down the street, nearly every woman’s face might look like his mother’s or every young man might resemble his brother. (I would predict that instead of having severed connections from face recognition areas to the amygdala, the Fregoli patient may have an excess of such connections. Every face would be imbued with familiarity and “glow,” causing him to see the same face over and over again.) Might such Fregoli−like confusion occur in otherwise normal brains? Could this be a basis for forming racist stereotypes? Racism is so often directed at a single physical type (Blacks, Asians, Whites and so forth). Perhaps a single unpleasant episode with one member of a visual category sets up a limbic connection that is inappropriately generalized to include all members of that class and is notoriously impervious to “intellectual correction” based on information stored in higher brain centers. Indeed one’s intellectual views may be colored (no pun intended) by this emotional knee−jerk reaction; hence the notorious tenacity of racism.

We began our journey with Arthur trying to explain his strange delusions about impostors and uncovered some new insights into how memories are stored and retrieved in the human brain. His story offers insights into how each of us constructs narratives about our life and the people who inhabit it. In a sense your life—your autobiography—is a long sequence of highly personal episodic memories about your first kiss, prom night, wedding, birth of a child, fishing trips and so on. But it is also much more than that. Clearly, there is a personal identity, a sense of a unified “self” that runs like a golden thread through the whole fabric of our existence. The Scottish philosopher David Hume drew an analogy between the human personality and a river—the water in the river is ever−changing and yet the river itself remains constant. What would happen, he asked, if a person were to dip his foot into a river and then dip it in again after half an hour – would it be the same river or a different one? If you think this is a silly semantic riddle, you’re right, for the answer depends on your definition of “same” and “river.”

But silly or not, one point is clear. For Arthur, given his difficulty with linking successive episodic memories, there may indeed be two rivers! To be sure, this tendency to make copies of events and objects was most pronounced when he encountered faces—Arthur did not often duplicate objects. Yet there were occasions when he would run his fingers through his hair and call it a “wig,” partly because his scalp felt unfamiliar as a result of scars from the neurosurgery he had undergone. On rare occasions, Arthur even duplicated countries, claiming at one point that there were two Panamas (he had recently visited that country during a family reunion).

Most remarkable of all, Arthur sometimes duplicated himself! The first time this happened, I was showing Arthur pictures of himself from a family photo album and I pointed to a snapshot of him taken two years before the accident.

“Whose picture is this?” I asked.

“That’s another Arthur,” he replied. “He looks just like me but it isn’t me.” I couldn’t believe my ears. Arthur may have detected my surprise since he then reinforced his point by saying, “You see? He has a mustache. I don’t.”

This delusion, however, did not occur when Arthur looked at himself in a mirror. Perhaps he was sensible enough to realize that the face in the mirror could not be anyone else’s. But Arthur’s tendency to “duplicate” himself—to regard himself as a distinct person from a former Arthur — also sometimes emerged spontaneously during conversation. To my surprise, he once volunteered, “Yes, my parents sent a check, but they sent it to the other Arthur.”

Arthur’s most serious problem, however, was his inability to make emotional contact with people who matter to him most—his parents— and this caused him great anguish. I can imagine a voice inside his head saying, “The reason I don’t experience warmth must be because I’m not the real Arthur.” One day Arthur turned to his mother and said, “Mom, if the real Arthur ever returns, do you promise that you will still treat me as a friend and love me?” How can a sane human being who is perfectly intelligent in other respects come to regard himself as two people? There seems to be something inherently contradictory about splitting the Self, which by its very nature is unitary. If I started to regard myself as several people, which one would I plan for? Which one is the “real” me? This is a real and painful dilemma for Arthur.

Philosophers have argued for centuries that if there is any one thing about our existence that is completely beyond question, it is the simple fact that “I” exist as a single human being who endures in space and time. But even this basic axiomatic foundation of human existence is called into question by Arthur.

Chapter 9
God and the Limbic System

Imagine you had a machine, a helmet of sorts that you could simply put on your head and stimulate any small region of your brain without causing permanent damage. What would you use the device for?

This is not science fiction. Such a device, called a transcranial magnetic stimulator, already exists and is relatively easy to construct. When applied to the scalp, it shoots a rapidly fluctuating and extremely powerful magnetic field onto a small patch of brain tissue, thereby activating it and providing hints about its function. For example, if you were to stimulate certain parts of your motor cortex, different muscles would contract. Your finger might twitch or you’d feel a sudden involuntary, puppetlike shrugging of one shoulder.

So, if you had access to this device, what part of your brain would you stimulate? If you happened to be familiar with reports from the early days of neurosurgery about the septum — a cluster of cells located near the front of the thalamus in the middle of your brain—you might be tempted to apply the magnet there. Patients “zapped” in this region claim to experience intense pleasure, “like a thousand orgasms rolled into one.” If you were blind from birth and the visual areas in your brain had not degenerated, you might stimulate bits of your own visual cortex to find out what people mean by color or “seeing.” Or, given the well−known clinical observation that the left frontal lobe seems to be involved in feeling “good,” maybe you’d want to stimulate a region over your left eye to see whether you could induce a natural high.

When the Canadian psychologist Dr. Michael Persinger got hold of a similar device a few years ago, he chose instead to stimulate parts of his temporal lobes. And he found to his amazement that he experienced God for the first time in his life.
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If religious beliefs are merely the combined result of wishful thinking and a longing for immortality, how do you explain the flights of intense religious ecstasy experienced by patients with temporal lobe seizures or their claim that God speaks directly to them? Many a patient has told me of a “divine light that illuminates all things,” or of an “ultimate truth that lies completely beyond the reach of ordinary minds who are too immersed in the hustle and bustle of daily life to notice the beauty and grandeur of it all.” Of course, they might simply be suffering from hallucinations and delusions of the kind that a schizophrenic might experience, but if that’s the case, why do such hallucinations occur mainly when the temporal lobes are involved? Even more puzzling, why do they take this particular form? Why don’t these patients hallucinate pigs or donkeys?
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The limbic system gets its input from all sensory systems—vision, touch, hearing, taste and smell. The latter sense is in fact directly wired to the limbic system, going straight to the amygdala (an almond−shaped structure that serves as a gateway into the limbic system). This is hardly surprising given that in lower mammals, smell is intimately linked with emotion, territorial behavior, aggression and sexuality.

The limbic system’s output, as Papez realized, is geared mainly toward the experience and expression of emotions. The experience of emotions is mediated by back−and−forth connections with the frontal lobes, and much of the richness of your inner emotional life probably depends on these interactions. The outward expression of these emotions, on the other hand, requires the participation of a small cluster of densely packed cells called the hypothalamus, a control center with three major outputs of its own. First, hypothalamic nuclei end hormonal and neural signals to the pituitary gland, which is often described as the “conductor” of the endocrine orchestra. Hormones released through this system influence almost every part of the human body, a biological tour de force we shall consider in the analysis of mind−body interactions (Chapter 11). Second, the hypothalamus sends commands to the autonomic nervous system, which controls various vegetative or bodily functions, including the production of tears, saliva and sweat and the control of blood pressure, heart rate, body temperature, respiration, bladder function, defecation and so on. The hypothalamus can be regarded, then, as the “brain” of this archaic, ancillary nervous system. The third output drives actual behaviors, often remembered by the mnemonic the “four F’s”— fighting, fleeing, feeding and sexual behavior. In short, the hypothalamus is the body’s “survival center,” preparing the body for dire emergencies or, sometimes, for the passing on of its genes.

Much of our knowledge about the functions of the limbic system comes from patients who have epileptic seizures originating in this part of the brain. When you hear the word “epilepsy,” you usually think of someone having fits or a seizure—the powerful involuntary contraction of all muscles of the body—and falling to the ground. Indeed, these symptoms characterize the most well−known form of epilepsy, called a grand mal seizure. Such seizures usually arise because a tiny cluster of neurons somewhere in the brain is misbehaving, firing chaotically until activity spreads like wildfire to engulf the entire brain. But seizures can also be “focal”; that is, they can remain confined largely to a single small patch of the brain. If such focal seizures are mainly in the motor cortex, the result is a sequential march of muscle twitching—or the so−called jacksonian seizures. But if they happen to be in the limbic system, then the most striking symptoms are emotional. Patients say that their “feelings are on fire,” ranging from intense ecstasy to profound despair, a sense of impending doom or even fits of extreme rage and terror. Women sometimes experience orgasms during seizures, although for some obscure reason men never do. But most remarkable of all are those patients who have deeply moving spiritual experiences, including a feeling of divine presence and the sense that they are in direct communion with God. Everything around them is imbued with cosmic significance. They may say, “I finally understand what it’s all about. This is the moment I’ve been waiting for all my life. Suddenly it all makes sense.” Or, “Finally I have insight into the true nature of the cosmos.” I find it ironic that this sense of enlightenment, this absolute conviction that Truth is revealed at last, should derive from limbic structures concerned with emotions rather than from the thinking, rational parts of the brain that take so much pride in their ability to discern truth and falsehood.
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Once, when Paul was reminiscing about his flashbacks, I interjected, “Paul, do you believe in God?”

He looked puzzled. “But what else is there?” he said.

But why do patients like Paul have religious experiences? I can think of four possibilities. One is that God really does visit these people. If that is true, so be it. Who are we to question God’s infinite wisdom?

Unfortunately, this can be neither proved nor ruled out on empirical grounds. The second possibility is that because these patients experience all sorts of odd, inexplicable emotions, as if a cauldron had boiled over, perhaps their only recourse is to seek ablution in the calm waters of religious tranquility. Or the emotional hodgepodge may be misinterpreted as mystical messages from another world. I find the latter explanation unlikely for two reasons. First, there are other neurological and psychiatric disorders such as frontal lobe syndrome, schizophrenia, manic depressive illness or just depression in which the emotions are disturbed, but one rarely sees religious preoccupations in such patients to the same degree. Even though schizophrenics may occasionally talk about God, the feelings are usually fleeting; they don’t have the same intense fervor or the obsessive and stereotyped quality that one sees in temporal lobe epileptics. Hence emotional changes alone cannot provide a complete explanation for religious preoccupation.

The third explanation invokes connections between sensory centers (vision and hearing) and the amygdala, that part of the limbic system specialized in recognizing the emotional significance of events in the external world. Obviously, not every person or event you encounter throughout a typical day sets off alarm bells; that would be maladaptive and you’d soon go mad. To cope with the world’s uncertainties, you need a way of gauging the salience of events before you relay a message to the rest of the limbic system and to the hypothalamus telling them to assist you in fighting or fleeing. But consider what might happen if spurious signals stemming from limbic seizure activity were to travel these pathways. You’d get the sort of kindling I described earlier. These “salience” pathways would become strengthened, increasing communication between brain structures. Sensory brain areas that see people and events and hear voices and noises would become more closely linked to emotional centers. The result? Every object and event—not just salient ones—would become imbued with deep significance, so that the patient would see “the universe in a grain of sand” and “hold[s] infinity in the palm of his hand.” He would float on an ocean of religious ecstasy, carried by a universal tide to the shores of Nirvana.

The fourth hypothesis is even more speculative. Could it be that human beings have actually evolved specialized neural circuitry for the sole purpose of mediating religious experience? The human belief in the supernatural is so widespread in all societies all over the world that it’s tempting to ask whether the propensity for such beliefs might have a biological basis. If so, you’d have to answer a key question: What sorts of Darwinian selection pressures could lead to such a mechanism? And if there is such a mechanism, is there a gene or set of genes concerned mainly with religiosity and spiritual leanings—a gene that atheists might lack or have learned to circumvent (just kidding!)?
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So we now have several competing hypotheses of why temporal lobe epileptics have such experiences. Even though all these theories invoke the same neural structures, they postulate very different mechanisms and it would be nice to find a way to distinguish among them. One of the ideas—the notion that kindling has indiscriminately strengthened all connections from the temporal cortex to the amygdala—can be addressed directly by studying the patient’s galvanic skin response. Ordinarily an object is recognized by the visual areas of the temporal lobes. Its emotional salience—is it a friendly face or a fierce lion?—is signaled by the amygdala and transmitted to the limbic system so that you become emotionally aroused and start sweating.

But if the kindling has strengthened all the connections within these pathways, then everything becomes salient. No matter what you look at—a nondescript stranger, a chair or a table—it should activate the limbic system strongly and make you perspire. So unlike you and me, who should display a heightened GSR response only for our moms, dads, spouses or lions, or even a loud thud or bang, the patient with temporal lobe epilepsy should show an increased galvanic skin response to everything under the sun.

To test this possibility, I contacted two of my colleagues who specialize in the diagnosis and treatment of epilepsy—Dr. Vincent Iragui and Dr. Evelyn Tecoma. Given the highly controversial nature of the whole concept of “temporal lobe personality” (not everyone agrees that these personality traits are seen more frequently in epileptics), they were quite intrigued by my ideas. A few days later, they recruited two of their patients who manifested obvious “symptoms” of this syndrome—hyper−graphia, spiritual leanings and an obsessive need to talk about their feelings and about religious and metaphysical topics. Would they want to volunteer in a research study?

Both were eager to participate. In what may turn out to be the very first scientific experiment ever done on religion directly, I sat them in comfortable chairs and attached harmless electrodes to their hands. Once settled in front of a computer screen, they were shown random samples of several types of words and images—for example, words for ordinary inanimate objects (a shoe, vase, table and the like), familiar faces (parents, siblings), unfamiliar faces, sexually arousing words and pictures (erotic magazine pinups), four−letter words involving sex, extreme violence and horror (an alligator eating a person alive, a man setting himself afire) and religious words and icons (such as the word “God”).

If you and I were to undergo this exercise, we would show huge GSR responses to the scenes of violence and to the sexually explicit words and pictures, a fairly large response to familiar faces and usually nothing at all to other categories (unless you have a shoe fetish, in which case you’d respond to one).

What about the patients? The kindling hypothesis would predict a uniform high response to all categories. But to our amazement what we found in the two patients tested was a heightened response mainly to religious words and icons. Their responses to the other categories, including the sexual words and images, which ordinarily evoke a powerful response, was strangely diminished compared to what is seen in normal individuals.
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I want to emphasize that not every temporal lobe epilepsy patient becomes religious. There are many parallel neural connections between the temporal cortex and the amygdala. Depending on which particular ones are involved, some patients may have their personalities skewed in other directions, becoming obsessed with writing, drawing, arguing philosophy or, rarely, being preoccupied with sex. It’s likely that their GSR responses would shoot upward in response to these stimuli rather than to religious icons, a possibility that is being studied in our laboratory and others.
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Darwin believed that his principle of natural selection could account not only for the emergence of morphological traits like fingers or noses, but also for the structure of the brain and therefore our mental capacities. In other words, natural selection could explain our talents for music, art, literature and other human intellectual achievements. Wallace disagreed. He conceded that Darwin’s principle might explain fingers and toes and maybe even some simple mental traits, but that certain quintessentially human abilities like mathematical and musical talent could not possibly have arisen through the blind workings of chance.

Why not? According to Wallace, as the human brain evolved, it encountered a new and equally powerful force called culture. Once culture, language and writing emerged, he argued, human evolution became Lamarckian—that is, you could pass on the accumulated wisdom of a lifetime to your offspring. These progeny will be much wiser than the offspring of illiterates not because your genes have changed but simply because this knowledge—in the form of culture—has been transferred from your brain to your child’s brain. In this way, the brain is symbiotic with culture; the two are as interdependent as the naked hermit crab and its shell or the nucleated cell and its mitochondria. For Wallace, culture propels human evolution, making us absolutely unique in the animal kingdom. Isn’t it extraordinary, he said, that we are the only animal in which the mind is vastly more important than any bodily organ, assuming a tremendous significance because of what we call “culture.” Moreover, our brain actually helps us avoid the need for further specialization. Most organisms evolve to become more and more specialized as they take up new environmental niches, be it a longer neck for the giraffe or sonar for the bat. Humans, on the other hand, have evolved an organ, a brain, that gives us the capacity to evade specialization. We can colonize the Arctic without evolving a fur coat over millions of years like the polar bear because we can go kill one, take its coat and drape it on ourselves. And then we can give it to our children and grandchildren.

Wallace’s second argument against “blind chance giving rise to the talents of a Mozart” involves what might be called potential intelligence (a phrase used by Richard Gregory). Say, you take a barely literate young tribesman from a contemporary aboriginal society (or even use a time machine to garner a Cro−Magnon man) and give him a modern public school education in Rio or New York or Tokyo. He will, of course, be no different from any other child reared in those cities. According to Wallace, this means that the aborigine or Cro−Magnon possesses a potential intelligence that vastly exceeds anything that he might need for coping with his natural environment. This kind of potential intelligence can be contrasted with kinetic intelligence, which is realized through formal education. But why the devil did this potential intelligence evolve? It couldn’t have arisen for learning Latin in English schools. It couldn’t have evolved for learning the calculus, even though almost anyone who tries hard enough can master it. What was the selection pressure for the emergence of these latent abilities? Natural selection can only explain the emergence of actual abilities that are expressed by the organism—never potential ones. When they are useful and promote survival, they are passed on to the next generation. But what to make of a gene for latent mathematical ability? What benefit does that confer on a nonliterate person? It seems like overkill.

Wallace wrote, “The lowest savages with the least copious vocabularies [have] the capacity of uttering a variety of distinct articulate sounds and of applying them to an almost infinite amount of modulation and inflection [which] is not in any way inferior to that of the higher [European] races. An instrument has been developed in advance of the needs of its possessor.” And the argument holds, with even greater force, for other esoteric human abilities such as mathematics or musical talent. There’s the rub. An instrument has been developed in advance of the needs of its possessor, but we know that evolution has no foresight! Here is an instance in which evolution appears to have foreknowledge. How is this possible?

Wallace wrestled mightily with this paradox. How can improvement in esoteric mathematical skills—in latent form—affect the survival of one race that has this latent ability and the extinction of another that doesn’t ? “It is a somewhat curious fact,” he wrote, “that when all modern writers admit the great antiquity of man, most of them maintain the very recent development of intellect, and will hardly contemplate the possibility of men, equal in mental capacity to ourselves, having existed in prehistoric times.” But we know they did. Both the Neanderthal and Cro−Magnon cranial capacities were actually larger than ours, and it’s not inconceivable that their latent potential intelligence may have been equal to or even greater than that of Homo sapiens. So how is it possible that these astonishing, latent abilities emerged in the prehistoric brain but have only been realized in the last one thousand years? Wallace’s answer: It was done by God! “Some higher intelligence must have directed the process by which the human nature was developed.” Thus human grace is an earthly expression of “divine grace.”

This is where Wallace parted company with Darwin, who resolutely maintained that natural selection was the prime force in evolution and could account for the emergence of even the most esoteric mental traits, without the helping hand of a Supreme Being. How would a modern biologist resolve Wallace’s paradox? She would probably argue that esoteric and “advanced” human traits like musical and mathematical ability are specific manifestations of what is usually called “general intelligence”—itself the culmination of a “runaway” brain that exploded in size and complexity within the last three million years. General intelligence evolved, the argument goes, so that one can communicate, hunt game, hoard food in granaries, engage in elaborate social rituals and do the myriad things that humans enjoy and that help them survive. But once this intelligence was in place, you could use it for all sorts of other things, like the calculus, music and the design of scientific instruments to extend the reach of our senses. By way of analogy, consider the human hand: Even though it evolved its amazing versatility for grasping at tree branches, it can now be used to count, write poetry, rock the cradle, wield a scepter and make shadow puppets.

But with respect to the mind, this argument doesn’t make much sense to me. I’m not saying it’s wrong, but the idea that the ability to spear antelope was then somehow used for the calculus is a bit dubious. I’d like to suggest another explanation, one that takes us back not only to the savant syndrome that I mentioned earlier but also to the more general question of the sporadic emergence of talent and genius in the normal population.
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These examples show that specialized esoteric talents do not emerge spontaneously from general intelligence, for if that were true, how can an “idiot” display them? Nor do we have to invoke the extreme pathological example of savants to make this point, for there is an element of this syndrome in every talented person or indeed in every genius. “Genius,” contrary to popular misconception, is not synonymous with superhuman intelligence. Most of the geniuses whom I have had the privilege of knowing are more like idiot savants than they would care to admit—extraordinarily talented in a few domains but quite ordinary in other respects.
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Chapter 10
The Woman Who Died Laughing

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I find great irony in the fact that every time someone smiles at you she is in fact producing a half threat by flashing her canines. When Darwin published On the Origin of Species he delicately hinted in his last chapter that we too may have evolved from apelike ancestors. The English statesman Benjamin Disraeli was outraged by this and at a meeting held in Oxford he asked a famous rhetorical question: “Is man a beast or an angel?” To answer this, he need only have looked at his wife’s canines as she smiled at him, and he’d have realized that in this simple universal human gesture of friendliness lies concealed a grim reminder of our savage past.

As Darwin himself concluded in The Descent of Man:
But we are not here concerned with hopes and fears, only with truth. We must acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which he feels for the most debased, with benevolence which extends not only to other men but to the humblest creature, with his Godlike intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers—man still bears in his bodily frame the indelible stamp of his lowly origin.

Chapter 11
“You Forgot to Deliver the Twin”

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So what causes pseudocyesis? Cultural factors undoubtedly play a major role and may explain the decline of pseudocyesis from an incidence of one in two hundred in the late 1700s to about one in ten thousand pregnancies today. In the past, many women felt extreme social pressure to have a baby, and when they felt they were pregnant, there was no ultrasound to disprove the diagnosis. No one could say with certainty, “Look here, there’s no fetus.” Conversely, pregnant women today submit to round after round of evaluations leaving little room for ambiguity; confronting the patient with physical evidence of an ultrasound is usually sufficient to dispel the delusion and associated physical changes.

The influence of culture on the incidence of pseudocyesis cannot be denied, but what causes the actual physical changes? According to the few studies carried out on this curious affliction of mind and body, the abdominal swelling itself is usually caused by a combination of five factors: an accumulation of intestinal gas, a lowering of the diaphragm, a pushing forward of the pelvic portion of the spine, a dramatic growth of the greater omentum—a pendulous apron of fat that hangs loose in front of the intestines—and in rare cases an actual uterine enlargement. The hypothalamus—a part of the brain that regulates endocrine secretions— may also go awry, producing profound hormonal shifts that mimic nearly all the signs of pregnancy. Furthermore, it’s a two−way street: The body’s effects on the mind are just as profound as those of the mind on the body, giving rise to complex feedback loops involved in generating and maintaining false pregnancy. For instance, the abdominal distension produced by gas and the woman’s “pregnant body posture” might be explained, in part, by classic operant conditioning. When Mary, who wants to be pregnant, sees her abdomen enlarge and feels her diaphragm fall, she learns unconsciously that the lower it falls, the more pregnant she looks. Likewise, a combination of air swallowing (aerophagia) and autonomic constriction of the gastrointestinal sphincters that would increase gas retention could also probably be learned unconsciously. In this manner, Mary’s “baby” and its “missing twin” are literally conjured out of thin air through a process of
unconscious learning.
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Pseudocyesis is dramatic. But is it an isolated, exceptional example of mind−body medicine? I think not. Other stories come to mind, including one I first heard in medical school. A friend said, “Did you know that according to Lewis Thomas you can hypnotize someone and eliminate their warts?”

“Rubbish,” I scoffed.

“No, it’s true,” she said. “There are documented cases. You get hypnotized and the warts disappear in a few days or sometimes overnight.”

Now on the face of it this sounds very silly, but if it’s true, it would have far−reaching implications for modern science. A wart is essentially a tumor (a benign cancer) produced by the papilloma virus. If that can be eliminated by hypnotic suggestion, why not cancer of the cervix, which is also produced by the papilloma virus (albeit a different strain)? I am not claiming that this will work—perhaps nerve pathways influenced by hypnosis reach the skin but not the lining of the cervix—but unless we do the relevant experiment, we will never know.

Assuming, for the sake of argument, that warts can be eliminated by hypnosis, the question arises, How can a person simply “think away” a tumor? There are at least two possibilities. One involves the autonomic nervous system—the pathways of nerves that help control blood pressure, sweating, heart rate, urine output, erections and other physiological phenomena not under direct control of conscious thought. These nerves form specialized circuits that service distinct functions in various body segments. Thus some nerves control hair standing on end, others cause sweating and some generate the local constriction of blood vessels. Is it possible that the mind, acting through the autonomic nervous system, could literally asphyxiate the wart by constricting blood vessels in its immediate vicinity, making it shrivel up and wither away? This explanation implies an unexpected degree of precise control by the autonomic nervous system and also implies that the hypnotic suggestion can be “understood” by the autonomic nervous system and transferred to the region of the wart.

The second possibility is that the hypnotic suggestion somehow kick starts the immune system, thereby eliminating the virus. But this would not explain at least one recorded case involving a hypnotized person whose warts vanished on just one side of his body. Why or how the immune system could selectively eliminate warts on one side over another is a mystery that invites further flights of speculation. A more common example of mind−body interaction involves the interplay between the immune system and perceptual cues from the world around us. Over three decades ago, medical students were often told that an asthmatic attack could be provoked not only by inhaling pollen from a rose but sometimes by merely seeing a rose, even a plastic rose, prompting a so−called conditioned allergic response. In other words, exposure to a real rose and pollen sets up a “learned” association in the brain between the mere visual appearance of a rose and bronchial constriction. How exactly does this conditioning work? How does the message get from the brain’s visual areas all the way down to the mast cells lining the bronchi of the lungs? What are the actual pathways involved? Despite three decades of mind−body medicine, we still have no clear answers.
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Chapter 12
Do Martians See Red?

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The central mystery of the cosmos, as far as I’m concerned, is the following: Why are there always two parallel descriptions of the universe—the first−person account (“I see red”) and the third−person account (“He says that he sees red when certain pathways in his brain encounter a wavelength of six hundred nanometers”)?

How can these two accounts be so utterly different yet complementary? Why isn’t there only a third−person account, for according to the objective worldview of the physicist and neuroscientist, that’s the only one that really exists? (Scientists who hold this view are called behaviorists.) Indeed, in their scheme of “objective science,” the need for a first−person account doesn’t even arise—implying that consciousness simply doesn’t exist. But we all know perfectly well that can’t be right. I’m reminded of the old quip about the behaviorist who, just having made passionate love, looks at his lover and says, “Obviously that was good for you, dear, but was it good for me?” This need to reconcile the first−person and third−person accounts of the universe (the “I” view versus the “he” or “it” view) is the single most important unsolved problem in science. Dissolve this barrier, say the Indian mystics and sages, and you will see that the separation between self and nonself is an illusion—that you are really One with the cosmos.

Philosophers call this conundrum the riddle of qualia or subjective sensation. How can the flux of ions and electrical currents in little specks of jelly—the neurons in my brain—generate the whole subjective world of sensations like red, warmth, cold or pain? By what magic is matter transmuted into the invisible fabric of feelings and sensations? This problem is so puzzling that not everyone agrees it is even a problem.
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As a second example, imagine a species of Amazonian electric fish that is very intelligent, in fact, as intelligent and sophisticated as you or I. But it has something we lack—namely, the ability to sense electrical fields using special organs in its skin. Like the superscientist in the previous example, you can study the neurophysiology of this fish and figure out how the electrical organs on the sides of its body transduce electrical current, how this information is conveyed to the brain, what part of the brain analyzes this information and how the fish uses this information to dodge predators, find prey and so on. If the fish could talk, however, it would say, “Fine, but you’ll never know what it feels like to sense electricity.”

These examples clearly state the problem of why qualia are thought to be essentially private. They also illustrate why the problem of qualia is not necessarily a scientific problem. Recall that your scientific description is complete. It’s just that the your account is incomplete epistemologically because the actual experience of electric fields or redness is something you never will know. For you, it will forever remain a “third−person” account.

For centuries philosophers have assumed that this gap between brain and mind poses a deep epistemological problem—a barrier that simply cannot be crossed. But is this really true? I agree that the barrier hasn’t yet been crossed, but does it follow that it can never be crossed? I’d like to argue that there is in fact no such barrier, no great vertical divide in nature between mind and matter, substance and spirit. Indeed, I believe that this barrier is only apparent and that it arises as a result of language. This sort of obstacle emerges when there is any translation from one language to another.

How does this idea apply to the brain and the study of consciousness? I submit that we are dealing here with two mutually unintelligible languages. One is the language of nerve impulses—the spatial and temporal patterns of neuronal activity that allow us to see red, for example. The second language, the one that allows us to communicate what we are seeing to others, is a natural spoken tongue like English or German or Japanese—rarefied, compressed waves of air traveling between you and the listener. Both are languages in the strict technical sense, that is, they are information−rich messages that are intended to convey meaning, across synapses between different brain parts in one case and across the air between two people in the other.

The problem is that I can tell you, the color−blind superscientist, about my qualia (my experience of seeing red) only by using a spoken language. But the ineffable “experience” itself is lost in the translation. The actual “redness” of red will remain forever unavailable to you.

But what if I were to skip spoken language as a medium of communication and instead hook a cable of neural pathways (taken from tissue culture or from another person) from the color−processing areas in my brain directly into the color−processing regions of your brain (remember that your brain has the machinery to see color even though your eyes cannot discriminate wavelengths because they have no color receptors)? The cable allows the color information to go straight from my brain to neurons in your brain without intermediate translation. This is a farfetched scenario, but there is nothing logically impossible about it.

Earlier when I said “red,” it didn’t make any sense to you because the mere use of the word “red” already involves a translation. But if you skip the translation and use a cable, so that the nerve impulses themselves go directly to the color area, then perhaps you’ll say, “Oh, my God, I see exactly what you mean. I’m having this wonderful new experience.”

This scenario demolishes the philosophers’ argument that there is an insurmountable logical barrier to understanding qualia. In principle, you can experience another creature’s qualia, even the electric fish’s. If you could find out what the electroceptive part of the fish brain is doing and if you could somehow graft it onto the relevant parts of your brain with all the proper associated connections, then you would start experiencing the fish’s electrical qualia. Now, we could get into a philosophical debate over whether you need to be a fish to experience it or whether as a human being you could experience it, but the debate is not relevant to my argument. The logical point I am making here pertains only to the electrical qualia—not to the whole experience of being a fish.

The key idea here is that the qualia problem is not unique to the mind−body problem. It is no different in kind from problems that arise from any translation, and thus there is no need to invoke a great division in nature between the world of qualia and the material world. There is only one world with lots of translation barriers. If you can overcome them, the problems vanish.
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Now you might ask, “Does any of this yield clues as to where in the brain qualia might be?” It is surprising that many people think that the seat of consciousness is the frontal lobes, because nothing dramatic happens to qualia and consciousness per se if you damage the frontal lobes— even though the patient’s personality can be profoundly altered (and he may have difficulty switching attention). I would suggest instead that most of the action is in the temporal lobes because lesions and hyperactivity in these structures are what most often produce striking disturbances in consciousness. For instance, you need the amygdala and other parts of the temporal lobes for seeing the significance of things, and surely this is a vital part of conscious experience. Without this structure you are a zombie (like the fellow in the famous Chinese room thought experiment proposed by the philosopher John Searle) capable only of giving a single correct output in response to a demand, but with no ability to sense the meaning of what you are doing or saying.

Everyone would agree that qualia and consciousness are not associated with the early stages of perceptual processing as at the level of the retina. Nor are they associated with the final stages of planning motor acts when behavior is actually carried out. They are associated, instead, with the intermediate stages of processing—a stage where stable perceptual representations are created (yellow, dog, monkey) and that have meaning (the infinite implications and possibilities for action from which you can choose the best one). This happens mainly in the temporal lobe and associated limbic structures, and, in this sense, the temporal lobes are the interface between perception and action.

The evidence for this comes from neurology; brain lesions that produce the most profound disturbances in consciousness are those that generate temporal lobe seizures, whereas lesions in other parts of the brain only produce minor disturbances in consciousness. When surgeons electrically stimulate the temporal lobes of epileptics, the patients have vivid conscious experiences. Stimulating the amygdala is the surest way to “replay” a full experience, such as an autobiographical memory or a vivid hallucination. Temporal lobe seizures are often associated not only with alterations in consciousness in the sense of personal identity, personal destiny and personality, but also with vivid qualia—hallucinations such as smells and sounds. If these are mere memories, as some claim, why would the person say, “I literally feel like I’m reliving it”? These seizures are characterized by the vividness of the qualia they produce. The smells, pains, tastes and emotional feelings—all generated in the temporal lobes—suggest that this brain region is intimately involved in qualia and conscious awareness.

Another reason for choosing the temporal lobes—especially the left one—is that this is where much of language is represented. If I see an apple, temporal lobe activity allows me to apprehend all its implications almost simultaneously. Recognition of it as a fruit of a certain type occurs in the inferotemporal cortex, the amygdala gauges the apple’s significance for my well−being and Wernicke’s and other areas alert me to all the nuances of meaning that the mental image—including the word “apple”—evokes; I can eat the apple, I can smell it; I can bake a pie, remove its pith, plant its seeds; use it to “keep the doctor away,” tempt Eve and on and on. If one enumerates all of the attributes that we usually associate with the words “consciousness” and “awareness,” each of them, you will notice, has a correlate in temporal lobe seizures, including vivid visual and auditory hallucinations, “out of body” experiences and an absolute sense of omnipotence or omniscience. Any one of this long list of disturbances in conscious experience can occur individually when other parts of the brain are damaged (for instance, disturbances of body image and attention in parietal lobe syndrome), but it’s only when the temporal lobes are involved that they occur simultaneously or in different combinations; that again suggests that these structures play a central role in human consciousness.

Until now we have discussed what philosophers call the “qualia” problem—the essential privacy and noncommunicability of mental states—and I’ve tried to transform it from a philosophical problem into a scientific one. But in addition to qualia (the “raw feel” of sensations), we also have to consider the self—the “I” inside you who actually experiences these qualia. Qualia and self are really two sides of the same coin; obviously there is no such thing as free−floating qualia not experienced by anyone and it’s hard to imagine a self devoid of all qualia.

But what exactly is the self? Unfortunately, the word “self” is like the word “happiness” or “love”; we all know what it is and know that it’s real, but it’s very hard to define it or even to pinpoint its characteristics. As with quicksilver, the more you try to grasp it the more it tends to slip away.
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If you doubt the reality of the social self, ask yourself the following question: Imagine that there is some act you’ve committed about which you are extremely embarrassed (love letters and Polaroid photographs from an illicit affair). Assume further that you now have a fatal illness and will be dead in two months. If you know that people rummaging through your belongings will discover your secrets, will you do your utmost to cover your tracks? If the answer is yes, the question arises, Why bother? After all, you know you won’t be around, so what does it matter what people think of you after you’re gone? This simple thought experiment suggests that the idea of the social self and its reputation is not just an abstract yarn. On the contrary, it is so deeply ingrained in us that we want to protect it even after death. Many a scientist has spent his entire life yearning obsessively for posthumous fame—sacrificing everything else just to leave a tiny scratchmark on the edifice.

So here is the greatest irony of all: that the self that almost by definition is entirely private is to a significant extent a social construct—a story you make up for others.

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2 responses to “Phantoms in the Brain – V.S. Ramachandran, Sandra Blakeslee

  1. hi Pankaj,

    Are you quoting from the book? Can you say something about why these ideas, in particular, are of interest to you?

    I found you while searching out a quote that I plan to use in a blogentry on paradigm consciousness.

    This excerpt from chapter 3 caught my attention.

    “…pain is an opinion on the organism’s state of health rather than a mere reflexive response to an injury.”

    I’m wondering as well about emotional pain (which is sometimes felt in the body), and the ways in which these ‘phantoms’ (to borrow Ramachadran’s term) may represent dynamics occurring socially within a group.

    best,
    steph

    • Dear Stephanie,

      Thanks for your interest in the blog.

      What you have read is a verbatim extract of the book. Nothing has been added or removed by me.

      About your interest in “the ways in which [emotional pain] and phantoms may represent dynamics occurring socially within a group” I would say that it is best explained in terms of “Mirror Neurons”. If that is shallow or insufficient then you can consider visiting
      http://www.intuition.co.in . The concept expounded there is “Intuitive Algorithm”. Difficult to understand the crux but if you can, then it explains a lot.

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