Phantoms in the Brain: Probing the Mysteries of the Human Mind (44 page)

Seen this way, filling in is a kind of treating and "preparing" of qualia to enable them to interact properly with limbic executive structures. Qualia may need to be filled in because gaps interfere with the proper working of these executive structures, reducing their efficiency and their ability to select an appropriate response. Like our general who ignores gaps in data given to him by scouts to avoid making a wrong decision, the control structure also finds a way to avoid gaps—by filling them in.15

Where in the limbic system are these control processes? It might be a system involving the amygdala and the anterior cingulate gyrus, given the amygdala's central role in emotion and the anterior cingulate's apparent executive role. We know that when these structures are disconnected, disorders of "free will" occur, such as akinetic mutism16 and alien hand syndrome. It is not difficult to see how such processes could give rise to the mythology of a self as an active presence in the brain—a "ghost in the machine."

The vigilant self:
A vital clue to the neural circuitry underlying qualia and consciousness comes from two other neurological disorders—pen−duncular hallucinosis and "vigilant coma" or akinetic mutism.

The anterior cingulate and other limbic structures also receive projections from the intralaminar thalamic nuclei (cells in the thalamus), which in turn are driven by clusters of cells in the brain stem (including the cholinergic lateral tegmental cells and the pendunculopontine cells).

peractivity of these cells can lead to visual hallucinations (penduncular hallucinosis), and we also know that schizophrenics have a doubling of cell number in these very same brain stem nuclei—which may contribute to their hallucinations.

Conversely, damage to the intralaminar nucleus or to the anterior cin−gulate results in coma vigilance or akinetic mutism. Patients with this curious disorder are immobile and mute and react sluggishly, if at all, to painful stimuli. Yet they are apparently awake and alert, moving their eyes around and tracking objects. When the patient comes out of this state, he may say, "No words or thoughts would come to my mind. I just didn't want to do or think or say anything." (This raises a fascinating question: Can a brain stripped of all motivation record any memories at all? If so, how much detail does the patient remember? Does he recall the neurologist's pinprick? Or the cassette tape that his girlfriend played for him?) Clearly these brain stem and thalamic circuits play an important role in consciousness and qualia. But it remains to be seen whether they merely play a "supportive" role for qualia (as indeed the liver and heart do!) or whether they are an integral part of the circuitry that embodies qualia and consciousness. Are they analogous to the power supply of a VCR or TV set or to the actual magnetic recording head and the electron gun in the cathode−ray tube?

The conceptual self and the social self:
In a sense, our concept of self is not fundamentally different from any other abstract concept we have— such as "happiness" or "love." Therefore, a careful examination of the different ways in which we use the word "I" in ordinary social discourse can provide some clues as to what the self is and what its function might be.

For instance, it is clear that the abstract self−concept also needs to have access to the "lower" parts of the system, so that the person can acknowledge or claim responsibility for different self−related facts: states of the body, body movements and so on (just as you claim to "control" your thumb when hitching a ride but not your knee when I tap the tendon with my rubber hammer). Information in autobiographical memory and information about one's body image need to be accessible to the self−concept, so that thought and talk about 171

self are possible. In the normal brain there are specialized pathways that allow such access to occur, but when one or more of these pathways is damaged, the system tries to do it anyway, and confabulation results. For instance, in the denial syndrome discussed in Chapter 7, there is no access channel between information about the left side of the body and the patient's self−

concept. But the self−concept is set up to try automatically to include that information. The net result of this is anosognosia or denial syndrome; the self "assumes" that the arm is okay and "fills in" the movements of that arm.

One of the attributes of the self−representation system is that the person will confabulate to try to cover up deficits in it. The main purposes of doing this, as we saw in Chapter 7, are to prevent constant indeci−siveness and to confer stability on behavior. But another important function may be to support the sort of created or narrative self that the philosopher Dan Dennett talks about—that we present ourselves as unified in order to achieve social goals and to be understandable to others. We also present ourselves as acknowledging our past and future identity, enabling us to be seen as part of society. Acknowledging and taking credit or blame for things we did in the past help society (usually kin who share our genes) incorporate us effectively in its plans, thereby enhancing the survival and perpetuation of our genes.17

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. In our discussion on denial, I suggested that confabulation and self−deception evolved mainly as by−products of the need to impose stability, internal consistency and coherence on behavior. But an added important function might stem from the need to conceal the truth from other people.

The evolutionary biologist Robert Trivers18 has proposed the ingenious argument that self−deception evolved mainly to allow you to lie with

complete conviction, as a car salesman can. After all, in many social situations it might be useful to lie—in a job interview or during courtship ("I'm not married"). But the problem is that your limbic system often gives the game away and your facial muscles leak traces of guilt. One way to prevent this, Trivers suggests, may be to deceive yourself first. If you actually believe your lies, there's no danger your face will give you away. And this need to lie efficiently provided the selection pressure for the emergence of self−deception.

I don't find Trivers's idea convincing as a
general
theory of self−deception, but there is one particular class of lies for which the argument carries special force: lying about your abilities or boasting. Through boasting about your assets you may enhance the likelihood of getting more dates, thereby disseminating your genes more effectively. The penalty you pay for self−deception, of course, is that you may become delusional. For example, telling your girlfriend that you're a millionaire is one thing; actually believing it is a different thing altogether, for you may start spending money you don't have! On the other hand, the advantages of boasting successfully (reciprocation of courtship gestures) may outweigh the disadvantage of delusion—at least up to a point. Evolutionary strategies are always a matter of compromsie.

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So can we do experiments to prove that self−deception evolved in a social context? Unfortunately, these are not easy ideas to test (as with all evolutionary arguments), but again our patients with denial syndrome whose defenses are grossly amplified may come to our rescue. When questioned by the physician, the patient denies that he is paralyzed, but would he deny his paralysis to
himself
'as well? Would he do it when nobody was watching? My experiments suggest that he probably would, but I wonder whether the delusion is amplified when others are present. Would his skin register a galvanic response as he confidently asserted that he could arm wrestle? What if we showed him the word "paralysis"? Even though he denies the paralysis, would he be disturbed by the word and register a strong GSR? Would a normal child show a skin change when confabulating (children are notoriously prone to such behavior)? What if a neurologist were to develop anosognosia (the denial syndrome) as the result of a stroke? Would he continue to lecture on this topic to his students—blissfully unaware that he himself was suffering from denial? Indeed, how do I know that I am not such a person? It's only through raising questions such as these that we can begin to approach the greatest scientific and philosophical riddle of all—the nature of the self.

Our revels now are ended. These our actors,

As I foretold you, were all spirits and

Are melted into air, into thin air.
...

We are such stuff

As dreams are made on,

And our little life

Is rounded with a sleep.

−−−−−−
William Shakespeare

During the last three decades, neuroscientists throughout the world have probed the nervous system in fascinating detail and have learned a great deal about the laws of mental life and about how these laws emerge from the brain. The pace of progress has been exhiliarating, but—at the same time—the findings make many people uncomfortable. It seems somehow disconcerting to be told that your life, all your hopes, triumphs and aspirations simply arise from the activity of neurons in your brain. But far from being humiliating, this idea is ennobling, I think. Science— cosmology, evolution and especially the brain sciences—is telling us that we have no privileged position in the universe and that our sense of having a private nonmaterial soul "watching the world" is really an illusion (as has long been emphasized by Eastern mystical traditions like Hinduism and Zen Buddhism). Once you realize that far from being a spectator, you are in fact part of the eternal ebb and flow of events in the cosmos, this realization is very liberating. Ultimately this idea also allows you to cultivate a certain humility—the essence of all authentic religious experience. It is not an idea that's easy to translate into words but comes very close to that of the cosmologist Paul Davies, who said: Through science, we human beings are able to grasp at least some of nature's secrets. We have cracked part of the cosmic code. Why this should be, just why
Homo sapiens
should carry the spark of rationality that provides the key to the universe, is a deep enigma. We, who are children of the universe— animated Stardust—can nevertheless reflect on the nature ofnthat same universe, even to the extent of glimpsing the rules on which it runs. How we have become linked into this cosmic dimension is a mystery. Yet the linkage cannot be denied.

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What does it mean? What is Man that we might be party to such privilege? I cannot believe that our existence in this universe is a mere quirk of fate, an accident of history, an incidental blip in the great cosmic drama.

Our involvement is too intimate. The physical species
Homo
may count for nothing, but the existence of mind in some organism on some planet in the universe is surely a fact of fundamental significance. Through conscious beings the

universe has generated self−awareness. This can be no trivial detail, no minor by−product of mindless, purposeless forces. We are truly meant to be here.

Are we? I don't think brain science alone, despite all its triumphs, will ever answer that question. But that we can ask the question at all is, to me, the most puzzling aspect of our existence.

(scanner: notes not scanned)

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