Phantoms in the Brain: Probing the Mysteries of the Human Mind (30 page)

remember ever having met Joe before. He will simply not recognize him. He will insist each time that Joe is a complete stranger, no matter how many times they have interacted, talked, exchanged stories and so forth.

But is Joe really a complete stranger? Rather surprisingly, experiments show that such amnesia patients actually retain the ability to form new categories that transcend successive Joe episodes. If our patient met Joe ten times and each time Joe made him laugh, he'd tend to feel vaguely jovial or happy on the next encounter but still would not know who Joe is. There would be no sense of familiarity whatsoever—no memory of each Joe episode—and yet the patient would acknowledge that Joe makes him happy. This means that the amnesia patient, unlike Arthur, can link successive episodes to create a new concept (an unconscious expectation of joy) even though he forgets each episode, whereas Arthur remembers each episode but fails to link them.

Thus Arthur is in some respects the mirror image of our amnesia patient. When he meets a total stranger like Joe, his brain creates a file for Joe and the associated experiences he has with Joe. But if Joe leaves the room for thirty minutes and returns, Arthur's brain—instead of retrieving the old file and adding to it—sometimes creates a completely new one.

Why does this happen in Capgras' syndrome? It may be that to link successive episodes the brain relies on signals from the limbic system— the "glow" or sense of familiarity associated with a known face and set of memories—and if this activation is missing, the brain cannot form an enduring category through time. In the absence of this glow, the brain simply sets up separate categories each time; that is why Arthur asserts that he is meeting a new person who simply resembles the person he met thirty minutes ago. Cognitive psychologists and philosophers often make a distinction between tokens and types—that all our experiences can be classified into general categories or tokens (people or cars) versus specific exemplars or types (Joe or my car).

Our experiments with Arthur suggest that this distinction is not merely academic; it is embedded deep in the architecture of the brain.

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 121

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.

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It is very difficult to elucidate this [cosmic religious] feeling to anyone who is entirely without it. . . . The
religious geniuses of all ages have been distinguished by this kind of religious feeling, which knows no
dogma. . . . In my view, it is the most important function of art and science to awaken this feeling and keep it
alive in those who are receptive to it.

—
Albert Einstein

[God] is the greatest democrat the world knows, for He leaves us "unfettered" to make our own choice
between evil and good. He is the greatest tyrant ever known, for He often dashes the cup from our lips and
under cover of free will leaves us a margin so wholly inadequate as to provide only mirth for Himself at our
expense. Therefore it is that Hinduism calls it all His sport (Lila), or calls it all an illusion (Maya). . . . Let us
dance to the tune of his bansi (flute), and all would be well.

—
Mohandas K. Gandhi

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.1 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.

I first heard about Dr. Persinger's strange experiment from my colleague, Patricia Churchland, who spotted an account of it in a popular Canadian science magazine. She phoned me right away. "Rama, you're not going to believe this. There's a man in Canada who stimulated his temporal lobe and experienced God. What do you make of it?"

"Does he have temporal lobe seizures?" I asked.

"No, not at all. He's a normal guy."

"But he stimulated his own temporal lobes?"

"That's what the article said."

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"Hmmmm, I wonder what would happen if you tried stimulating an atheist's brain. Would he experience God?" I smiled to myself and said, "Hey, maybe we should try the device on Francis Crick."

Dr. Persinger's observation was not a complete surprise as I've always suspected that the temporal lobes, especially the left lobe, are somehow involved in religious experience. Every medical student is taught that patients with epileptic seizures originating in this part of the brain can have intense, spiritual experiences during the seizures and sometimes become preoccupied with religious and moral issues even during the seizure−free or interictal periods.

But does this syndrome imply that our brains contain some sort of circuitry that is actually specialized for religious experience? Is there a "God module" in our heads? And if such a circuit exists, where did it come from? Could it be a product of natural selection, a human trait as natural in the biological sense as language or stereoscopic vision? Or is

there a deeper mystery at play, as a philosopher, epistemologist or theologian might argue?

Many traits make us uniquely human, but none is more enigmatic than religion—our propensity to believe in God or in some higher power that transcends mere appearances. It seems very unlikely that any creature other than humans can ponder the infinite or wonder about "the meaning of it all." Listen to John Milton in
Paradise Lost:

For who would lose, though full of pain

This intellectual being

Those thoughts that wander through eternity to be swallowed up
and lost In the wide womb of uncreated night.

But where do such feelings come from? It may be that any intelligent sentient being that can look into its own future and confront its own mortality will sooner or later begin to engage in such disquieting ruminations.

Does my little life have any real significance in the grand scheme of things? If my father's sperm had not fertilized that particular egg on that fateful night, would I not have existed, and in what real sense then would the universe have existed? Would it not then, as Erwin Schrö−dinger said, have been a mere "play before empty benches"? What if my dad had coughed at that critical moment so that a different sperm had fertilized the ovum? Our minds start reeling when pondering such possibilities. We are bedeviled by paradox: On the one hand our lives seem so important—with all those cherished highly personal memories—and yet we know that in the cosmic scheme of things, our brief existence amounts to nothing at all. So how do people make sense of this dilemma? For many the answer is straightforward: They seek solace in religion.

But surely there's more to it than that. 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