The Mind and the Brain (3 page)

The heart of the book describes the burgeoning field of neuro
plasticity—how plasticity is induced by changes in the amount of sensory stimulation reaching the brain. Neuroplasticity can result not only in one region of the brain colonizing another—with remarkable effects on mental and physical function—but also in the wholesale remodeling of neural networks, of which the changes in the brains of OCD patients are only one example. The discovery that neuroplasticity can be induced in people who have suffered a stroke demonstrated, more than any other finding, the clinical power of a brain that can rewire itself.

It was through my informal collaboration with the physicist Henry Stapp, a preeminent scholar of the interpretation of quantum mechanics, that my tentative musings on the causal efficacy of attention and will found a firm basis in physics. Stapp’s youthful pursuit of the foundations of quantum physics evolved, in his later years, into an exploration of the mind’s physical power to shape the brain. It has long been Stapp’s contention that the connection between consciousness and the brain is (
pace
, philosophers) primarily a problem in physics and addressable by physics—but only the correct physics. Though you would hardly know it from the arguments of those who appeal to physics to assert that all mental phenomena can be reduced to the electrochemical activity of neurons, physics has progressed from its classical Newtonian form and found itself in the strange land of the quantum. Once, physics dealt only with tangible objects: planets, balls, molecules, and atoms. Today, in the form of quantum mechanics, it describes a very different world, one built out of what Stapp calls “a new kind of stuff,” with properties of both the physical and the mental. The physics that informs the neuroscience I describe is, I think, one of the features that make this book different from those that have come before, for it is in quantum mechanics that the hypotheses born of studies of OCD and the mind find their harmonizing voice. What we now know about quantum physics gives us reason to believe that conscious thoughts and volitions can, and do, play a powerful
causal role in the world, including influencing the activity of the brain. Mind and matter, in other words,
can
interact.

One result of my collaboration with Stapp was a short paper we wrote for the
Journal of Consciousness Studies
. In it, we marshaled evidence from neuroscience and quantum physics to argue for the existence and causal efficacy of volition. In his 1890 masterpiece
The Principles of Psychology
, William James argued that the ability to fix one’s attention on a stimulus or a thought and “hold it fast before the mind” was the act that constituted “the essential achievement of the will.” If the effort to hold an object in one’s attention is determined wholly by the properties of that object and its effects on the nervous system, then the case for free will is weak. If, however, one can make more or less effort, as one chooses, and so willfully “prolong the stay in consciousness of innumerable ideas which else would fade away more quickly,” then free will remains a real scientific possibility.

James struggled throughout his life to find a rigorous alternative to the reductive determinism that ruled science in his day and has persisted down to ours. Although he rejected determinism on ethical grounds, as a working scientist he had to admit that “the utmost a believer in free-will can
ever
do will be to show that the deterministic arguments are not coercive. That they are seductive, I am the last to deny.” But although determinism has indeed seduced both the scientifically sophisticated and the scientifically innocent for well over a century, its arguments are not “coercive.” During the reign of classical physics one could be excused for thinking otherwise. But not anymore. Individuals choose what they will attend to, ignoring all other stimuli in order to focus on one conversation, one string of printed characters, or, in Buddhist mindfulness meditation, one breath in and one breath out.

In the last section of the book, we explore this third rail of neuroscience: the existence, character, and causal efficacy of will. There, I propose that the time has come for science to confront the
serious implications of the fact that directed, willed mental activity can clearly and systematically alter brain function; that the exertion of willful effort generates a
physical force
that has the power to change how the brain works and even its physical structure. The result is directed neuroplasticity. The cause is what I call directed mental force.

Mainstream philosophical and scientific discourse may remain strongly biased toward a materialist perspective. Yet the simple fact is that the materialism of classical physics offers no intuitively meaningful way of explaining the critical role played by the will in the brain changes seen in OCD patients. The striving of the mind to be free of its inner compulsions—what Buddhists call Right Effort—is much more than just the play of electrochemical impulses within a material construct. In this book, I describe experimental data that support an alternative, offering evidence that the brain truly is the child of the mind.

How? Through the mental act of focusing attention, mental effort becomes directed mental force. “[T]he effort to attend,” James believed, may well be a true and genuine “original force.” Modern neuroscience is now demonstrating what James suspected more than a century ago: that attention is a mental state (with physically describable brain state correlates) that allows us, moment by moment, to “choose and sculpt how our ever-changing minds will work, [to] choose who we will be the next moment in a very real sense…. Those choices are left embossed in physical form on our material selves.” If James was speaking metaphorically, he was also speaking with almost eerie prescience. For it is now clear that the attentional state of the brain produces physical change in its structure and future functioning. The seemingly simple act of “paying attention” produces real and powerful physical changes in the brain. In fact, Stapp’s work suggests that there
is
no fully defined brain state until attention is focused. That physical activity within the brain follows the focus of attention offers the clearest explanation to date of how my hypothesized mental force can alter brain
activity. The choice made by a patient—or, indeed, anyone—causes one physical brain state to be activated rather than another. A century after the birth of quantum mechanics, it may at last be time to take seriously its most unsettling idea: that the observer and the way he directs his attention are intrinsic and unavoidable parts of reality.

Finally, in the Epilogue, we attempt to come to terms with why any of this matters. One important answer is that the materialist-determinist model of the brain has profound implications for notions like moral responsibility and personal freedom. The interpretation of mind that dominates neuroscience is inimical to both. For if we truly believe, when the day is done, that our mind and all that term entails—the choices we make, the reactions we have, the emotions we feel—are nothing but the expression of a machine governed by the rules of classical physics and chemistry, and that our behavior follows ineluctably from the workings of our neurons, then we’re forced to conclude that the subjective sense of freedom is a “user illusion.” Our sense that we are free to make moral decisions is a cruel joke, and society’s insistence that individuals (with exceptions for the very young and the mentally ill) be held responsible for their actions is no more firmly rooted in reason than a sand castle is rooted in the beach. In stark contrast to the current paradigm, however, the emerging research on neuroplasticity, attention, and the causal efficacy of will supports the opposite view—one that demands the recognition of moral responsibility.

And it does something more. The implications of directed neuroplasticity combined with quantum physics cast new light on the question of humankind’s place, and role, in nature. At its core, the new physics combined with the emerging neuroscience suggests that the natural world evolves through an interplay between two causal processes. The first includes the physical processes we are all familiar with—electricity streaming, gravity pulling. The second includes the contents of our consciousness, including volition. The importance of this second process cannot be overstated, for it
allows human thoughts to make a difference in the evolution of physical events.

Because the question of mind—its existence and its causal efficacy—is central to our thesis, let us turn first to an exploration of a problem as ancient as philosophy and as modern as the latest discovery of genes that “cause” risk taking, or shyness, or happiness, or impulsivity—or any of the dozens of human behavioral traits that are now being correlated with the chemical messages encoded on our twisting strands of DNA.

Let us turn to the duality of mind and brain.

Of all the thousands of pages and millions of words devoted to the puzzle of the mind and the brain, to the mystery of how something as sublime and insubstantial as thought or consciousness can emerge from three pounds of gelatinous pudding inside the skull, my favorite statement of the problem is not that of one of the great philosophers of history, but of a science fiction writer. In a short story first published in the science and sci-fi magazine
Omni
in 1991, the Hugo-winning author Terry Bisson gets right to the heart of the utter absurdity of the situation: that an organ made from basically the same material ingredients (nucleated, carbon-based, mitochondria-filled cells) as, say, a kidney, is able to generate this ineffable thing called mind. Bisson’s story begins with this conversation between an alien commander and a scout who has just returned from Earth to report the results of his reconnaissance:

“They’re made out of meat.”

“Meat?”

“There’s no doubt about it. We picked several from different parts of the planet, took them aboard our recon vessels, probed them all the way through. They’re completely meat.”

“That’s impossible. What about the radio signals? The messages to the stars?”

“They use the radio waves to talk, but the signals don’t come from them. The signals come from machines.”

“So who made the machines? That’s who we want to contact.”

“They made the machines. That’s what I’m trying to tell you. Meat made the machines.”

“That’s ridiculous. How can meat make a machine? You’re asking me to believe in sentient meat.”

“I’m not asking you, I’m telling you. These creatures are the only sentient race in the sector and they’re made of meat.”

“Maybe they’re like the Orfolei. You know, a carbon-based intelligence that goes through a meat stage.”

“Nope. They’re born meat and they die meat. We studied them for several of their lifespans, which didn’t take too long. Do you have any idea of the lifespan of meat?”

“Spare me. Okay, maybe they’re only part meat. You know, like the Weddilei. A meat head with an electron plasma brain inside.”

“Nope, we thought of that, since they do have meat heads like the Weddilei. But I told you, we probed them. They’re meat all the way through.”

“No brain?”

“Oh, there is a brain all right. It’s just that the brain is made out of meat.”

“So…what does the thinking?”

“You’re not understanding, are you? The brain does the thinking. The meat.”

“Thinking meat! You’re asking me to believe in thinking meat!”

“Yes, thinking meat! Conscious meat! Loving meat. Dreaming meat. The meat is the whole deal! Are you beginning to get the picture, or do I have to start all over?”

It was some 2,500 years ago that Alcmaeon of Croton, an associate of the Pythagorean school of philosophy who is regarded as the founder of empirical psychology, proposed that conscious experience originates in the stuff of the brain. A renowned medical and physiological researcher (he practiced systematic dissection), Alcmaeon further theorized that all sensory awareness is coordinated by the brain. Fifty years later, Hippocrates adopted this notion of the brain as the seat of sensation, writing in his treatise on seizures: “I consider that the brain has the most power for man…. The eyes and ears and tongue and hands and feet do whatsoever the brain determines…it is the brain that is the messenger to the understanding [and] the brain that interprets the understanding.” Although Aristotle and the Stoics rejected this finding (seating thought in the heart instead), today scientists know, as much as they know anything, that all of mental life springs from neuronal processes in the brain. This belief has dominated studies of mind-brain relations since the early nineteenth century, when phrenologists attempted to correlate the various knobs and bumps on the skull with one or another facet of personality or mental ability. Today, of course, those correlations are a bit more precise, as scientists, going beyond the phrenologists’ conclusion that thirty-seven mental faculties are represented on the surface of the skull, do their mapping with brain imaging technologies such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), which pinpoint which brain neighborhoods are active during any given mental activity.

This has been one of the greatest triumphs of modern neuroscience, this mapping of whole worlds of conscious experience—from recognizing faces to feeling joy, from fingering a violin string to
smelling a flower—onto a particular cluster of neurons in the brain. It began in the 1950s, when Wilder Penfield, a pioneer in the neurosurgery of epilepsy, electrically stimulated tiny spots on the surface of patients’ brains (a painless procedure, since neurons have no feeling). The patients were flooded with long-forgotten memories of their grandmother or heard a tune so vividly that they asked the good doctor why a phonograph was playing in the operating theater. But it is not merely the precision of the mental maps that has increased with the introduction of electrodes—and later noninvasive brain imaging—to replace the skull-bump cartography beloved of phrenologists. So has neuroscientists’ certainty that tracing different mental abilities to specific regions in the brain—verbal working memory to a spot beneath the left temple, just beside the region that encodes the unpleasantness of pain and just behind the spot that performs exact mathematical calculations—is a worthy end in itself. So powerful and enduring has been Alcmaeon’s hypothesis about the seat of mental life, and his intellectual descendants’ equating of brain and mind, that most neuroscientists today take for granted that once you have correlated activity in a cluster of neurons with a cognitive or emotional function—or, more generally, with any mental state—you have solved the problem of the origin of mental events. When you trace depression to activity in a circuit involving the frontal cortex and amygdala, you have—on the whole—explained it. When you link the formation of memories to electrochemical activities in the hippocampus, you have learned everything worth knowing about it. True, there are still plenty of details to work out. But the most deeply puzzling question—whether that vast panoply of phenomena encompassed by the word
mind
can actually arise from nothing but the brain—is not, in the view of most researchers, a legitimate subject for scientific inquiry. Call it the triumph of materialism.

To the mainstream materialist way of thinking, only the physical is real. Anything nonphysical is at best an artifact, at worst an
illusion. In this school of philosophy, at least among those who don’t dismiss the reality of mind entirely, the mind is the software running on the brain’s hardware. Just as, if you got right down to the level of logic gates and speeding electrons, you could trace out how a computer told to calculate 7 x 7 can spit out 49, so you could, in principle, determine in advance the physical, neural correlates in the brain of any action the mind will ever carry out. In the process, every nuance of every mental event would be explained, with not even the smallest subtlety left as a possibly spontaneous (from the Latin
sponte
, meaning “of one’s free will, voluntarily”) occurrence.

A friend of mine, the neurosurgeon Joseph Bogen, recalled to me a remark that the Nobelist David Hubel made to him in 1984: “The word Mind is obsolete.” Hubel was stating exactly the conclusion of researchers who equate their brain scans and neuronal circuit diagrams with a full understanding of mental processes. Now that we understand so much about the brain, this reasoning holds, there’s no longer any need to appeal to such a naïve term, with its faint smack of folk psychology. As Hubel said to Bogen, the very word
mind
“is like the word
sky
for astronomers.” It’s only fair to note that this view has not been unanimous. In fact, no sooner had brain imaging technology produced its neat maps than neuroscientists began to question whether we will “understand the brain when the map…is completely filled with blobs,” as the neurobiologists M. James Nichols and William Newsome asked in a 1999 paper. “Obviously not,” they answered. Still, in many sophisticated quarters,
mind
was becoming not merely an obsolete word but almost an embarrassing one.

But if you equate the sequential activation of neurons in the visual pathway, say, with the perception of a color, you quickly encounter two mysteries. The first is the one that befuddled our alien commander. Just as the human brain is capable of differentiating light from dark, so is a photodiode. Just as the brain is capable of differentiating colors, so is a camera. It isn’t hard to rig up a
photodiode to emit a beep when it detects light, or a camera to chirp when it detects red. In both cases, a simple physical device is registering the same perception as a human brain and is announcing that perception. Yet neither device is conscious of light or color, and neither would become so no matter how sophisticated a computer we rigged it up to. There is a difference between a programmed, deterministic mechanical response and the mental process we call consciousness. Consciousness is more than perceiving and knowing; it is
knowing
that you know.

If it seems ridiculous even to consider why a handful of wires and transistors fails to generate subjective perceptions, then ask the same question about neurons outside the brain. Why is it that no neurons other than those in a brain are capable of giving the owner of that brain a qualitative, subjective sensation—an inner awareness? The activity of neurons in our fingertips that distinguish hot from cold, for example, is not associated in and of itself with conscious perception. But the activity of neurons in the brain, upstream of the fingertips’ sensory neurons, is. If the connection linking the fingers to the brain through the spinal cord is severed, all sensation in those fingers is lost. What is it about the brain that has granted to its own neurons the almost magical power to create a felt, subjective experience from bursts of electrochemical activity little different from that transpiring downstream, back in the fingertips? This represents one of the central mysteries of how matter (meat?) generates mind.

The second mystery is that the ultimate result of a rain of photons falling on the retina is…well, a sense. A sense of crimson, or navy blue. Although we can say that
this
wavelength of light stimulates
this
photosensitive cone in the retina to produce
this
sense of color—650 nanometers makes people with normal color vision see red, for instance—science is silent on the genesis of the feeling of red, or cerulean, or other
qualia
. This is the term many philosophers have adopted for the qualitative, raw, personal, subjective feel that we get from an experience or sensation. Every conscious state has a
certain feel to it, and possibly a unique one: when you bite into a hamburger, it feels different from the experience of chewing a steak. And any taste sensation feels different from the sound of a Chopin étude, or the sight of a lightning storm, or the smell of bourbon, or the memory of your first kiss. Identifying the locus where red is generated, in the visual cortex, is a far cry from explaining our sense of redness, or why seeing red
feels
different from tasting fettuccine Alfredo or hearing “Für Elise”—especially since all these experiences reflect neuronal firings in one or another sensory cortex. Not even the most detailed fMRI gives us more than the physical basis of perception or awareness; it doesn’t come close to explaining what it feels like from the inside. It doesn’t explain the first-person feeling of red. How do we know that it is the same for different people? And why would studying brain mechanisms, even down to the molecular level, ever provide an answer to those questions?

It is, when you think about it, a little peculiar to believe that when you have traced a clear causal chain between molecular events inside our skull and mental events, you have explained them sufficiently, let alone explained the mind in its entirety. If nothing else, there’s a serious danger of falling into a category error here, ascribing to particular clusters of neurons properties that they do not possess—in this case, consciousness. The philosopher John Searle, who has probed the mysteries of mind and brain as deeply as any contemporary scholar, has described the problem this way: “As far as we know, the fundamental features of [the physical] world are as described by physics, chemistry and the other natural sciences. But the existence of phenomena that are not in any obvious way physical or chemical gives rise to puzzlement…. How does a mental reality, a world of consciousness, intentionality and other mental phenomena, fit into a world consisting entirely of physical particles in fields of force?” If the answer is that it doesn’t—that mental phenomena are different in kind from the material world of particles—then what we have here is an
explana
tory gap
, a term first used in this context by the philosopher Joseph Levine in his 1983 paper “Materialism and Qualia: The Explanatory Gap.”

And so, although correlating physical brain activity with mental events is an unquestionable scientific triumph, it has left many students of the brain unsatisfied. For neither neuroscientist nor philosopher has adequately explained how the behavior of neurons can give rise to subjectively felt mental states. Rather, the puzzle of how patterns of neuronal activity become transformed into subjective awareness, the neurobiologist Robert Doty argued in 1998, “remains the cardinal mystery of human existence.” Yet there is no faster way to discomfit a room of neuroscientists than to confront them with this mind-body problem, or mind-matter problem, as it is variously called. To avoid it, cellular neurophysiologists position their blinders so their vision falls on little but the particulars of nerve conduction—ions moving in and out, electrical pulses traveling along an axon, neurotransmitters flowing across a synapse. As the evolutionary biologist Richard Lewontin puts it, “One restricts one’s questions to the domain where materialism is unchallenged.”