Phantoms in the Brain: Probing the Mysteries of the Human Mind (43 page)

What are these characteristics that define the self? William Hirstein, a postdoctoral fellow in my lab, and I came up with the following list:

The embodied self:
My Self is anchored within a single body. If I close my eyes, I have a vivid sense of different body parts occupying space (some parts more felt than others)—the so−called body image. If you pinch my toe, it is "I" who experiences the pain, not "it." And yet the body image, as we have seen, is 167

extremely malleable, despite all its appearance of stability. With a few seconds of the right type of sensory stimulation, you can make your nose three feet long or project your hand onto a table (Chapter 3)! And we know that circuits in the parietal lobes, and the regions of the frontal lobes to which they project, are very much involved in constructing this image. Partial damage to these structures can cause gross distortions in body image; the patient may say that her left arm belongs to her mother or (as in the case of the patient I saw with Dr. Riita Hari in Helsinki) claim that the left half of her body is still sitting in the chair when she gets up and walks! If these examples don't convince you that your "ownership" of your body is an illusion, then nothing will.

The passionate self:
It is difficult to imagine the self without emotions—or what such a state could even mean. If you don't see the meaning or significance of something—if you cannot apprehend all its implications—in what sense are you really aware of it consciously? Thus your emotions—mediated by the limbic system and amygdala—are an essential aspect of self, not just a "bonus." (It is a moot point whether a purebred Vulcan, like Spock's father in the original
Star Trek,
is really conscious or whether he is just a zombie—unless he is also tainted by a few human genes as Spock is.) Recall that the "zombie" in the "how"

pathway is unconscious, whereas the "what" pathway is conscious, and I suggest that the difference arises because only the latter is linked to the amygdala and other limbic structures (Chapter 5).

The amygdala and the rest of the limbic system (in the temporal lobes) ensures that the cortex—indeed, the entire brain—serves the organism's basic evolutionary goals. The amygdala monitors the highest level of perceptual representations and "has its fingers on the keyboard of the autonomic nervous system"; it determines whether or not to respond emotionally to something and what kinds of emotions are appropriate (fear in response to a snake or rage to your boss and affection to your child). It also receives information from the insular cortex, which in turn

is driven partially by sensory input not only from the skin but also from the viscera—heart, lung, liver, stomach—so that one can also speak of a "visceral, vegetative self or of a "gut reaction" to something. (It is this "gut reaction," of course, that one monitors with the GSR machine, as we showed in Chapter 9, so that you could argue that the visceral self isn't, strictly speaking, part of the conscious self at all. But it can nevertheless profoundly intrude on your conscious self; just think of the last time you felt nauseous and threw up.)

Pathologies of the emotional self include temporal lobe epilepsy, Cap−gras' syndrome and Klüver−Bucy syndrome. In the first, there may be a heightened sense of self that may arise partly through a process that Paul Fedio and D. Bear call "hyperconnectivity"—a strengthening of connections between the sensory areas of the temporal cortex and the amygdala. Such hyperconnectivity may result from repeated seizures that cause a permanent enhancement (kindling) of these pathways, leading the patient to ascribe deep significance to everything around him (including himself!). Conversely, people with Capgras' syndrome have reduced emotional response to certain categories of objects (faces) and people with Klüver−Bucy or Cotard's syndrome have more pervasive problems with emotions (Chapter 8). A Cotard's patient feels so emotionally remote from the world and from himself that he will actually make the absurd claim that he is dead or that he can smell his flesh rotting.

Interestingly, what we call "personality"—a vital aspect of your self that endures for life and is notoriously impervious to "correction" by other people or even by common sense—probably also involves the very same limbic structures and their connections with the ventromedial frontal lobes. Damage to the frontal lobes produces no obvious, immediate disturbance in consciousness, but it can profoundly alter your personality.

When a crowbar pierced the frontal lobes of a railway worker named Phineas Gage, his close friends and relatives remarked, "Gage wasn't Gage anymore." In this famous example of frontal lobe damage, Gage was transformed from a stable, polite, hardworking young man into a lying, cheating vagabond who could not hold down a job.14

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Temporal lobe epilepsy patients like Paul in Chapter 9 also show striking personality changes, so much so that some neurologists speak of a "temporal lobe epilepsy personality." Some of them (the patients, not the neurologists) tend to be pedantic, argumentative, egocentric and garrulous. They also tend to be obsessed with

"abstract thoughts." If these traits are a result of hyperfunctioning of certain parts of the temporal lobe, what exactly is the normal function of these areas? If the

limbic system is concerned mainly with emotions, why would seizures in these areas cause a tendency to generate abstract thought? Are there areas in our brains whose role is to produce and manipulate abstract thoughts? This is one of the many unsolved problems of temporal lobe epilepsy.15

The executive self:
Classical physics and modern neuroscience tell us that you (including your mind and brain) inhabit a deterministic billiard ball universe. But you don't ordinarily experience yourself as a puppet on a string; you feel that you are in charge. Yet paradoxically, it is always obvious to you that there are some things you can do and others you cannot given the constraints of your body and of the external world. (You know you can't lift a truck; you know you can't give your boss a black eye, even if you'd like to.) Somewhere in your brain there are
representations
of all these possibilities, and the systems that plan commands (the cingulate and supplementary motor areas in the frontal lobes) need to be aware of this distinction between things they can and cannot command you to do. Indeed, a "self that sees itself as completely passive, as a helpless spectator, is no self at all, and a self that is hopelessly driven to action by its impulses and urgings is equally effete. A self needs free will—what Deepak Chopra calls "the universal field of infinite possibilities"—even to exist. More technically, conscious awareness has been described as a "conditional readiness to act."

To achieve all this, I need to have in my brain not only a representation of the world and various objects in it but also a representation of myself, including my own body within that representation—and it is this peculiar recursive aspect of the self that makes it so puzzling. In addition, the representation of the external object has to interact with my self−representation (including the motor command systems) in order to allow me to make a choice. (He's your boss; don't sock him. It's a cookie; it's within your reach to grab it.) Derangements in this mechanism can lead to syndromes like anosognosia or somatoparaphrenia (Chapter 7) in which a patient will with a perfectly straight face claim that her left arm belongs to her brother or to the physician.

What neural structure is involved in representing these "embodied" and "executive" aspects of the self?

Damage to the anterior cingulate gyrus results in a bizarre condition called "akinetic mutism"—the patient simply lies in bed unwilling to do or incapable of doing anything even though he appears to be fully aware of his surroundings. If there's such a thing as absence of free will, this is it.

Sometimes when there is partial damage to the anterior cingulate, the very opposite happens: The patient's hand is uncoupled from her conscious thoughts and intentions and attempts to grab things or even perform relatively complex actions without her permission. For example, Dr. Peter Halligan and I saw a patient at Rivermead Hospital in Oxford whose left hand would seize the banister as she walked down the steps and she would have to use her other hand forcibly to unclench the fingers one by one, so she could continue walking.

Is the alien left hand controlled by an unconscious zombie, or is it controlled by parts of her brain that have qualia and consciousness? We can now answer this by applying our three criteria. Does the system in her brain that moves her arm create an irrevocable representation? Does it have short−term memory? Can it make a choice?

Both the executive self and the embodied self are deployed while you are playing chess and assume you're the queen as you plan "her" next move. When you do this, you can almost feel momentarily that you are inhabiting the queen. Now one could argue that you're just using a figure of speech here, that you're not literally assimilating the chess piece into your body image. But can you really be all that sure that the loyalty of your mind to your
own
body is not equally a "figure of speech"? What would happen to your GSR if I 169

suddenly punched the queen? Would it shoot up as though I were punching your own body? If so, what is the justification for a hard−and−fast distinction between her body and yours? Could it be that your tendency normally to identify with your "own" body rather than with the chess piece is also a matter of convention, albeit an enduring one? Might such a mechanism also underlie the empathy and love you feel for a close friend, a spouse or−a child who is literally made from your own body?

The mnemonic self:
Your sense of personal identity—as a single person who endures through space and time—depends on a long string of highly personal recollections: your autobiography. Organizing these memories into a coherent story is obviously vital to the construction of self.

We know that the hippocampus is required for acquiring and consolidating new memory traces. If you lost your hippocampi ten years ago, then you will not have any memories of events that occurred after that date.

You are still fully conscious, of course, because you have all the memories prior to that loss, but in a very real sense your existence was frozen at that time.

Profound derangement to the mnemonic self can lead to multiple personality disorder or MPD. This disorder is best regarded as a malfunction of the same coherencing principle I alluded to in the discussion of denial in Chapter 7. As we saw, if you have two sets of mutually incompatible beliefs and memories about yourself, the only way to prevent anarchy and endless strife may be to create two personalities within one body—the so−called multiple personality disorder. Given the obvious relevance of this syndrome to understanding the nature of self, it is astonishing how little attention it has received from mainstream neurology.

Even the mysterious trait called hypergraphia—the tendency of temporal lobe epilepsy patients to maintain elaborate diaries—may be an exaggeration of the same general tendency: the need to create and sustain a coherent worldview or autobiography. Perhaps kindling in the amygdala causes every external event and internal belief to acquire deep significance for the patient, so there is an enormous proliferation of spuriously self−relevant beliefs and memories in his brain. Add to this the compelling need we all have from time to time to take stock of our lives, see where we stand; to review the significant episodes of our lives periodically—and you have hypergraphia, an exaggeration of this natural tendency. We all have random thoughts during our day−to−day musings, but if these were sometimes accompanied by miniseizures—producing euphoria—then the musings themselves might evolve into obsessions and entrenched beliefs that the patient would keep returning to whether in his speech or in his writing. Could similar phenomena provide a neural basis for zealotry and fanatacism?

The unified self
—
imposing coherence on consciousness, filling in and confabulation:
Another important attribute of self is its unity—the internal coherence of its different attributes. One way to approach the question of how our account of qualia relates to the question of the self is to ask why something like filling in of the blind spot with qualia occurs. The original motive many philosophers had for arguing that the blind spot is
not
filled in was that there is no person in the brain to fill it in for—that no little homunculus is watching.

Since there's no little man, they argued, the antecedent is also false: Qualia are not filled in, and thinking so is a logical fallacy. Since I argue that qualia are in fact filled in, does this mean that I believe they are filled in for a homunculus? Of course not. The philosopher's argument is really a straw man. The line of reasoning should run, If qualia are filled in, they are filled in for
something
and what is that "something"? There exists in certain branches of psychology the notion of an executive, or a control process, which is generally thought to be located in the prefrontal and frontal parts of the brain. I would like to suggest that the

"something" that qualia are filled in for is not a "thing" but simply another brain process, namely, executive processes associated with the limbic system including parts of the anterior cingulate gyrus. This process connects your perceptual qualia with specific emotions and goals, enabling you to make choices—very much the sort of thing that the self was traditionally supposed to do. (For example, after having lots of tea, I have the 170

sensation or urge—the qualia—to urinate but I'm giving a lecture so I choose to delay action until the talk is finished but also choose to excuse myself at the end instead of taking questions.) An executive process is not something that has all the properties of a full human being, of course. It is not a homunculus. Rather, it is a process whereby some brain areas such as those concerned with perception and motivation influence the activities of other brain areas such as ones dealing with the planning of motor output.