As long as the brain is a mystery, the universe will also be a mystery.
—Santiago Ramón y Cajal
One of the most misleading representational techniques in our language is the use of the word “I.”
—Ludwig Wittgenstein
When I think of the relationship between the universe and the human brain an image that comes to mind is that of a tree—not just its glorious crown of branches but also its system of roots, which may extend as far into the earth as the branches spread to the sky. To me, the branches symbolize the observed universe, while the roots symbolize the brain. Both systems are constantly growing and evolving, and they depend on each other.
One might object that this makes too much of the roots: The brain, after all, is far less complex and extensive than the universe, which can get along fine without us. But the symmetry of the metaphor is preserved if we think of the branches as referring to the perceived universe. That universe exists only so long as there is someone to perceive it. Moreover, it is the only universe we can ever know. Neither we nor any other thinking beings can comprehend any more of the universe than what we can make of it in our minds. In that sense, roots and branches—mind and cosmos—are mutually dependent and forever equal.
They are symmetrical, too, in that we tend to think of the universe and the brain as each being one thing. Why we should do so intrigues me, and the next chapter investigates the concept of the universe as a unified whole. Here I want to examine the assumption that each of us has but one brain.
Like most people I think of myself as of one mind. I say, “I have made up my mind,” not, “I have made up my minds.” In this I have plenty of company; so universal is the doctrine of “one man, one mind” that it constitutes a hallmark of mental health; to act as if you were of several minds is to risk commitment to a mental ward. As the American brain researcher Michael Gazzaniga writes, “The strong subjective sense we all possess of ourselves is that we are a single, unified, conscious agent controlling life’s events with a singular, integrated purpose.”
And yet, as Gazzaniga adds, “It is not true.” His research and that of many colleagues reveals that the brain is by no means monolithic, but consists of many different modules—Gazzaniga calls them “programs”—that function more or less independently. How many programs are there? Nobody knows. Some estimate the number at a dozen or so. Gazzaniga thinks it may be as high as a hundred or more. Nobody who has studied the brain thinks the number is one.
Now you may have noticed that I am indulging in a bit of sleight of hand here, by saying “mind” when I refer to the sense of personal unity that each mentally healthy person possesses, and “brain” when I claim that we contain multitudes. And this, the mind-brain question, is indeed the crux of the problem.
Brain is easy to define: It is the wet, oatmeal-colored organ, weighing about three pounds, that resides inside the skull, along with such appurtenances (the eye, the spinal cord) as the neurologists see fit to include in their concept of the brain. Its physical multiplicity is unquestionable: Anatomists have identified hundreds of brain parts, on which they have bestowed enough bewildering names to give medical students migraine headaches—the frontal lobes, the parietal and occipital lobes, motor and sensory cortex, Wernicke’s area, Broca’s area, the cingulate gyrus, the pulvinar, the cerebral aqueduct and peduncle, the pineal body, the cerebellorubrothalamic tract, the commissure of fornix, the nucleus of Darkschewitsch, the island of Reil, Ammon’s horn, and the interstitial nucleus of Cajal.
One way to bring order to the complexity of the brain is to study how it has evolved over time, a process that is to some extent recapitulated in the growth of the human embryo. This research has established that the brain stem—the bulb where the brain meets the spine—is the oldest part, with the midbrain and higher brain having been built atop it in something like the way that the newer buildings of an ancient city are constructed on the foundations of the old. This perspective informs the “triune brain” paradigm, propounded by the American neuroscientist Paul MacLean, which divides the brain into three systems: At the base resides the “reptilian complex,” responsible for aggression, territoriality, and ritual; above that is found the limbic system, seat of powerful emotions, sexual instincts, and the sense of smell; and over the top arches the neocortex, the most recent and most distinctly human system, generator of language and geometry, “the mother of invention and father of abstract thought,” in MacLean’s words.
Mind is a slipperier concept. A statement of its various definitions takes up three full pages of the Oxford English Dictionary. For our purposes we can define “mind” as the subject of consciousness—the totality of thoughts, feelings, and sensations presented by the brain to that segment of it that is conscious. But as we will see, consciousness forms a much smaller part of the operations of the brain than was once supposed. Mind is not the all-knowing monarch of the brain, but a little circle of firelight in a dark, Australia-sized continent where the unconscious brain processes carry on.
Freud, the Magellan of the subconscious, was the first to appreciate this. Whatever may have been the limitations of his analysis of the unconscious, Freud appreciated its vast extent and called attention to its veiled influences on the mind. These influences highlight the curious question of how and why, given that the brain is multipartite, it represents itself to the mind as unified. Were our conscious selves perfectly unified, we would feel justified in concluding that the brain for all the disparity of its parts is in truth a fully unified system. But we find, instead, that our sense of personal unity and command over the brain is an imperfect illusion, like the mechanical regent constructed by the Wizard of Oz to impress his subjects. Evidence of an underlying multiplicity keeps peeking from behind the scrim, and what it reveals is that each of us, like the wider universe, is made of many different entities.
This strange circumstance—that one’s mind neither controls nor comprehends most of what goes on in one’s brain—is emphasized in the results of two recent experiments. One was conducted by Benjamin Libet, a neurophysiologist at the School of Medicine of the University of California at San Francisco. The other was pioneered by Roger Sperry and his colleagues at the California Institute of Technology and expanded upon by Sperry’s students, Gazzaniga among them.
Libet asked the subjects of his experiments simply to flex one finger. To do so would seem to be a purely volitional act, one that the conscious mind orders and the rest of the nervous system carries out. But Libet’s results proved otherwise.
Libet wired up his subjects with electrodes that measure brain activity, and seated them in full view of a rapidly rotating clock hand that enabled them to note exactly when they “ordered” their finger to flex. Libet could then mark three events in time: The onset of increased brain activity recorded by the electrodes, the flexing of the finger, and the point at which each subject had consciously willed his finger to flex.
What Libet found was that in each instance, a flurry of brain activity took place a fraction of a second before the “order” to flex the finger was dispatched by the conscious mind. “In other words,” says Libet, “their neurons were firing a third of a second before they were even conscious of the desire to act. Hence, it appeared the brain had begun preparing for movement long before the mind had ‘decided’ to do anything.”
The illusion of conscious control is maintained, Libet notes, because another mechanism in the brain delays the sensation of the finger moving, so that the conscious mind continues to think that it has first decreed the action, then felt the muscles act. Actually, by the time the mind orders the finger to flex, the impulse has already been dispatched. All the mind gets is a last-minute opportunity to veto the decision: I can stop my finger from flexing by sending an intercept command that overtakes and interrupts the original command and thus keeps my finger immobile. (This is what happens when you reach for a plate in the kitchen, then stop yourself upon remembering that the plate is hot.) The mind is thus permitted to sustain the flattering illusion that it controls the game. In actuality it is playing catch-up ball.
It is not difficult to conjecture why we should have evolved the pleasing if illusory conviction that we both control and understand more of the brain than we do: He who hesitates is lost, and I can act more quickly and decisively if I imagine that “I”—my mind—is running the show. But how does the brain so constantly and consistently fool the mind?
Light was shed on this question in experiments conducted by Sperry, Gazzaniga, and others on what are called “split brain” patients. The cerebrum—the seat of thought and voluntary action—is divided into two lobes or hemispheres. In most individuals, the left cerebral hemisphere processes visual information from the right side of each eye’s field of view, and controls the right side of the body, while the right hemisphere performs the same functions for the left side. Communication between the two hemispheres is handled by the corpus callosum, a bundle of over two hundred million nerve fibers. Sufferers from grand mal epilepsy may find relief through a surgical procedure in which the corpus callosum is cut, terminating communication between the right and left sides of the higher brain. Typically these individuals go on to lead normal lives, with few obvious side effects. But careful studies of their perceptions and actions has taught scientists a great deal about how the brain works.
In the 1950s, Sperry and his colleagues flashed pictures on a screen in such a way that their subjects could see them on only one side of their field of view. This apparatus could, for example, show a picture to the right brain while keeping the left brain in the dark. In a normal individual this would make little difference; the corpus callosum, a high-bandwidth transmission channel that shuttles information back and forth between lobes, would inform the left brain of what the right brain had seen. But a split-brain patient has lost the use of the corpus callosum; consequently his left brain has little or no way of knowing what the right brain has seen.
This made it possible, by studying split-brain patients, to identify certain functions as localized in one or the other hemisphere. Language, for instance, turned out to be a function primarily of the left brain. When a word is flashed to the right hemisphere of a split-brain patient, she cannot tell the researcher what the word was. The left brain, which handles speech, does not know what to say, because it has not seen the word. The right brain knows, but cannot speak. It can, however, answer questions in other ways. In one experiment, a subject’s right brain was shown a picture of an apple; he could not say what he had been shown, but when his left hand (the hand controlled by the right brain) was given several hidden objects to choose from, it picked the apple.
Generalizations about the proclivities of the right and left cerebral hemispheres—adept, respectively, at patterns and words—spread from Sperry’s laboratories to become part of the broader culture, where they were sometimes put to rather facile uses. Writers were declared to be “left-brain” types, painters to be “right-brain” dominated. Golfers and tennis players were trained to engage their right brain functions in order to play more naturally and gracefully. School administrators endeavored to address the supposedly neglected right brain by putting more stress on arts and crafts.
But the implications of localized brain functions can also help us understand the unity of mind. The split-brain experiments indicate that the brain is made up of many modules that operate more or less independently, and that the function of the mind is not so much to tell the other units what to do as to try to make some coherent sense out of what they already have chosen to do.
This was where Gazzaniga came in. He worked with split-brain patients whose right hemispheres had sufficient linguistic facility to understand simple commands. (Some people, especially the left-handed, distribute part of their language processing to the right hemisphere.) When a command—”Walk!”—was flashed to such a patient’s right brain, he got up and began to walk out of the room. The remarkable thing is that when asked, the patient invariably came up with a rational though bogus explanation for his actions. Asked, “Where are you going?” a typical response was something like, “Uh, I’m going to get a Coke.”
This behavior calls to mind a similar phenomenon often observed in connection with hypnosis. “Under hypnosis the patient is given a post-hypnotic suggestion,” writes the philosopher John Searle, of the University of California, Berkeley. “You can tell him, for example, to do some fairly trivial, harmless thing, such as, let’s say, crawl around on the floor. After the patient comes out of hypnosis, he might be engaging in conversation, sitting, drinking coffee, when suddenly he says something like, ‘What a fascinating floor in this room!’ or ‘I want to check out this rug, ’or I’m thinking of investing in floor coverings and I’d like to investigate this floor.’ He then proceeds to crawl around on the floor.
“Now the interest of these cases,” Searle notes, “is that the patient always gives some more or less adequate reason for doing what he does.” We rationalize our actions, explaining them in terms we ourselves accept as true, even when our conscious mind is ignorant of the motives behind them. The posthypnotic subject does not know why he is crawling around on the floor; this knowledge was blocked from him under hypnosis. Gazzaniga’s split-brain patients do not know, either, why they suddenly get up and walk away, communications having been severed between the right hemisphere, which received the command, and the left hemisphere, which is called upon to account for it. Yet all these subjects readily explain their behavior. And evidently they believe the explanation, even though the experimenter can tell that it’s a fabrication.
The implication seems clear that there is a program in the brain responsible for presenting the mind with plausible explanations for actions, and that it acts, so to speak, unscrupulously, blithely explaining matters about which it is uninformed. Gazzaniga calls this program “the interpreter,” and he notes that its functioning accounts for the embarrassing fact that we all from time to time hear ourselves saying something patently false. “The realization that the mind has a modular organization suggests that some of our behavior might have no origins in our conscious thought process,” Gazzaniga writes. “For example, we just happen to eat frogs’ legs for the first time…. While the interpreter does not actually know why there was an impulse to consume frogs’ legs it might hypothesize, ‘Because I want to learn about French food.’” Who among us has not uttered such a lame, silly phrase, and wondered where it came from? Gazzaniga’s answer is that it comes from the interpreter program.
The interpreter may be seen at work in the phenomenon of cognitive dissonance. Long remarked upon by psychologists, cognitive dissonance occurs when we find ourselves acting in ways that contradict our moral precepts, and seek to explain away the disparity. In one oft-cited study, students who said they deplored cheating were given an examination under conditions in which it was easy to cheat; those who succumbed to temptation and cheated, when queried anew about their ethical precepts, expressed less condemnatory attitudes toward cheating than they had before. Gazzaniga’s explanation is that since much of our behavior is not controlled by the conscious mind in the first place, the interpreter program often is called upon to put a good face on dissonant behavior, and does so by presenting the conscious mind with a self-serving rationale for what we have done.
Gazzaniga’s results indicate that the interpreter is located in the left cerebral hemisphere, near the speech center. This makes sense, in that language is the great explainer—and counterfeiter—of human motives and actions. In the twentieth century we have seen the interpreter working overtime, turning out reams of Orwellian doublespeak, from the Nazis who put a sign above the death camp gates reading “Obedience to the Law is Freedom,” to the military publicist who coined the term “preemptive response” to describe the bombing of Vietnamese cities. Gazzaniga’s research suggests that sophistry and propaganda succeed because they employ techniques that the interpreter has been using all along to preen and persuade our vain and limited minds. “Language,” says Gazzaniga, “is merely the press agent for these other variables of cognition.”
We are confronted, then, with the prospect that the sense of unity and control that the conscious mind presents to each mentally healthy individual is an illusion. (In this sense, the crazy person who hears a multitude of competing voices in his mind is saner than the rest of us, just as poets have been saying for centuries.) The brain is not unified, nor is the mind in control; it only seems that way, thanks to the ceaseless public relations efforts of the interpreter—and, perhaps, of other similar programs not yet identified. The mind may rule the self, but it is a constitutional monarch; presented with decisions already made elsewhere in the brain, it must try somehow to put on a good show of their adding up to some coordinated, sensible pattern. Functionally it resembles Ronald Reagan’s presidency: It acts as if it were in control, and thinks it is in control, and believes it has good reasons for what it does, when in actuality it is often just mouthing soothing rationalizations while obeying the orders of unseen agencies hidden offstage.
The brain is analogous to a computer in that it disguises a multiplicity of operations behind a unified facade. The computer on which I am typing this sentence is busy doing many things at once—one part of it is keeping track of time, another is searching sectors in one of its disc drives, another is moving blocks of data here and there in its memory—but the image it paints on the screen is coherent and unitary, like the picture presented to the mind by the brain. At the moment, that image replicates black letters inked on white paper. If I press a few keys to access another program, the image will change to replicate a chess board, the stars over Padua on a summer night in the year 1692, or an air battle over the Pacific in 1942. In every instance the unified image is a scrim, presented by a program that in turn interfaces with other programs. The brain similarly renders the multiple functions of its several programs into a pleasing if illusory unity.
And this, I suspect, could describe the psychology of the galaxy-wide computer network I was describing earlier in this book. The network might regard itself as intelligent, but most of what it knows would have come from agencies that it could never really understand—the living, thinking beings on the many worlds that had contributed knowledge to the network. In much the same way, our minds rely upon entities within the brain that we do not understand. Though the network might think it wanted to bring new worlds into contact and to establish communications links with other galaxies, in reality it merely had been programmed to do so—just as we, for all we know, are carrying out instructions coded in our genes, their message and intent a mystery to us.
Perhaps that is the fate of all intelligence, everywhere—to act in ways it thinks are volitional, while never knowing whether instead it actually is playing a role in some unglimpsed master plan. I wonder how many minds, from here to the galaxies of the Hydra Supercluster, have asked themselves the same question: Are we free agents who seek to learn about the universe, or are we a means by which the universe seeks to learn about itself?