The Mind and the Brain (43 page)

In late 1998 I happened on a paper by Mike Merzenich and Rob
deCharms that fortified my belief that attention is the mechanism by which the mind effects the expression of volition. The two UCSF scientists noted that when an individual pays attention to some stimulus, the neurons in the cerebral cortex that represent this object show increased activation. But Merzenich and deCharms took this observation further. In addition, they noted, “the pattern of activity of neurons in sensory areas can be altered by patterns of attention, leading to measured shifts in receptive fields or tuning of individual neurons.” If individual neurons can be tuned to different stimuli, depending on the mind’s attentional state, they concluded, then “entire spatial maps across the cortical surface are systematically distorted by attention…[which] implies a rapid remapping of the representational functions of the cortex.”

The cortex, that is, is as subject to remapping through attention as it is through the changes in sensory input described in our survey of neuroplasticity. In addition, in all three of the cortical systems where scientists have documented neuroplasticity—the primary auditory cortex, somatosensory cortex, and motor cortex—the variable determining whether or not the brain changes is not the sensory input itself but, crucially, the attentional state of the animal. In 1993 Merzenich showed that passive stimulation alone simply did not cut it. He and his students repeatedly exposed monkeys to specific sound frequencies. When the monkeys were trained to pay attention, the result was the expected tonotopic reorganization of the auditory cortex: the representation of the repeatedly heard frequency expanded. But when the monkeys were distracted by another task, and so were paying little or no attention to the tones piped into their ears, no such tonotopic expansion occurred. Inputs that the monkey does not pay attention to fail to produce long-term cortical changes; closely attended behaviors and inputs do. Let me repeat: when stimuli
identical
to those that induce plastic changes in an attending brain are instead delivered to a nonattending brain, there is no induction of cortical plasticity. Attention, in other words, must be paid.

Since attention is generally considered an internally generated state, it seems that neuroscience has tiptoed up to a conclusion that would be right at home in the canon of some of the Eastern philosophies: introspection, willed attention, subjective state—pick your favorite description of an internal mental state—can redraw the contours of the mind, and in so doing can rewire the circuits of the brain, for it is attention that makes neuroplasticity possible. The role of attention throws into stark relief the power of mind over brain, for it is a mental state (attention) that has the ability to direct neuroplasticity. In so doing, it has the power to alter the very landscape of the brain. “Experience coupled with attention leads to physical changes in the structure and future functioning of the nervous system,” Merzenich and deCharms concluded. “This leaves us with a clear physiological fact…moment by moment we choose and sculpt how our ever-changing minds will work, we choose who we will be the next moment in a very real sense, and these choices are left embossed in physical form on our material selves.”

I had long suspected that attention (especially mindfully directed attention) was the key to the brain changes in OCD patients I was successfully treating with the Four Steps. This was precisely why the Refocusing step was so critical: paying attention to an alternative activity was the means by which the brain changed, quieting activity in the OCD circuit. So it was gratifying to see that Merzenich had collected evidence that focusing attention was the critical action effecting neuroplastic changes in the cortex. And as we saw in Chapter 6, purely mental rehearsal of the kind Alvaro Pascual-Leone and colleagues had volunteers perform with a piano exercise—imagining themselves playing it though not actually doing so—was an early hint of the power of attention. The volunteers may not have been touching the ivories, but their intense concentration on the sequence of notes was enough to increase the representation of those fingers in the motor cortex. They were literally thinking themselves into a new brain.

Similarly, Ed Taub had shown that the more stroke patients
concentrated on their tasks—the more they paid attention—the greater their functional reorganization and recovery. In stroke patients who sustain damage to the prefrontal cortex, and whose attention systems are therefore impaired, recovery is much less likely. Two months after the stroke, a simple measure of attention, such as the patient’s ability to count tones presented through headphones, predicts almost uncannily how well the patient will recover motor function. The power of attention, that is, determines whether a stroke patient will remain incapacitated or not. Ian Robertson’s research group at Trinity College found much the same thing: “How well people can pay attention just after a right-brain stroke predicts how well they can use their left hands two years later.” If the attention circuits in the frontal lobes are damaged by the stroke, the patient recovers less well from injury to other regions of the brain than if the frontal lobes are spared.

The powers of attention being reported by neuroscientists around the world in the late 1990s made me suspect that the process of self-directed brain reorganization I continued to document in my OCD patients might also reflect the workings of attention. In particular, I wondered whether the power of attention to bias brain function might also account for an OCD patient’s ability to suppress the neuronal activation caused by obsessive thoughts and strengthen the neuronal activation caused by healthy ones. But even hypothesizing that the specific action an OCD patient chooses to focus attention on (washing hands versus tinkering with the car engine) determines which neuronal representation becomes stronger and which fades away threatens to plunge us down the rabbit hole of Cartesian dualism. In the simplest formulation, do OCD patients—indeed, does any of us?—have a choice about what to pay attention to? Or is attention fully determined by passive brain mechanisms? William James, in the passages I read to Henry Stapp on Christmas Eve, recognized that either was logically possible. If attention is fully determined by a stimulus, then if you knew the
precise neuronal wiring and the trillions of synapses in a human brain you could predict precisely what—which stimulus in the environment, or which of the countless thoughts percolating just below the radar of consciousness—a person would pay attention to. The materialist reductionists believe that, under those conditions, we could indeed make such a prediction.

But although we can predict with confidence some of the stimuli that will catch our attention, like the snake that leaps onto the forest path we are hiking or the
boom!
of a building being demolished, we cannot predict others. The
meaning
of experience—how the product of those trillions of synapses will be interpreted by the mind—is inexplicable if you use only materialistic terms. In the case of my OCD patients, whether they attend to the insistent inner voice telling them they left the stove on, or to the voice of mindfulness telling them that message is nothing more (or less) than the manifestation of faulty brain wiring, is
not
predictable. In this case, the ego-dystonic nature of OCD symptoms (the fact that the characteristic intrusive thoughts and urges are experienced as extraneous and alien to the self) enables most patients to distinguish clearly between the competing calls. OCD symptoms can therefore be viewed as painfully amplified versions of the mental events that pass through the mind innumerable times in the course of a day. Most of these mental events are experienced passively, and as outside volitional control; they are often described as “popping into your head.” They are thoughts and ideas that may have an identifiable trigger, perhaps a melody that triggers a memory or a sight that prompts a related thought, but feel as if they arise through deterministic mental circuitry over which we have little if any control. They arise unbidden; fleeting, transitory, evanescent, they differ from the thoughts that beset OCD sufferers only in that the latter are much more insistent, discomfiting, and intrusive. OCD thoughts grab the sufferer’s attention so insistently that it takes great effort to ignore them. In this way, OCD obsessions illuminate
critical differences between mental events that we experience passively and with no apparent effort and those that require significant effort to focus attention on. This aspect of the disease, as I noted earlier, is what attracted me to its study: the hope that such a condition would shed light on the relationship between the mind and the brain and, in particular, on whether mind is causally efficacious in its actions on the brain.

James’s dictum “Volitional effort is effort of attention” captures the way OCD patients manage to shift their brain out of pathological thought patterns and into healthy ones. In OCD, two different neural systems compete for attention. One, generated passively and by the pathological brain circuitry underlying the disease, insists you wash your hands again. The other, generated by the active, willful effort characteristic of the Four Steps, beckons to an alternative, healthy behavior, such as gardening. It is the choice of which one to allow into one’s attention, which one to hold “steadily before the mind until it
fills
the mind,” that shapes subsequent actions. (Even in James’s time, OCD was considered a powerful model of when and how something goes wrong with the will. He himself used it as a prime example of a disease of the will.) When my OCD patients succeed in ignoring the siren call of their obsessions, they do so through the power of their attention to hold fast before the mind the image of the healthy alternative to a compulsive act. No one with an ounce of empathy would deny that this requires tremendous effort.

To Henry Stapp, the idea of attention as the motive force behind volition suggested how mind might interact with the quantum brain—how an act of mental effort could focus a stream of consciousness that would otherwise quickly become defocused. Now, for the first time since we began our informal collaboration, Stapp began contemplating a place in his theory for the notion of mental effort. To produce what he would come to call a
quantum theory of consciousness
, he had to reach back through the decades, to his stu
dent days at Berkeley in the 1950s. After earning his undergraduate degree in physics from the University of Michigan in 1950, Stapp began work on his Ph.D. thesis at the University of California, Berkeley. His aim was to erect a theoretical framework to analyze the proton-proton scattering experiments being conducted on the cyclotron by Emilio Segrè and Owen Chamberlain (who shared the 1959 Nobel Prize in physics for their discovery of the antiproton). In these experiments, incoming
protons
(the positively charged components of atomic nuclei) caromed off other protons. At first the incoming protons were
polarized
(that is, had their spin vectors aligned) in a certain, known direction. Once they hit the stationary protons they scattered away, with a different polarization. It was logical to expect that this final polarization would have something to do with the initial polarization—or as physicists say, that the polarizations would be correlated. One of Segrè and Chamberlain’s bright graduate students, Tom Ypsilantis, happened to be Stapp’s roommate. One day, he asked Stapp for help analyzing the scattering result. The work eventually turned into Stapp’s thesis and made him familiar with particle correlations.
Correlated particles
—those separated in space or time but sharing a common origin—were soon to trigger a revolution in our understanding of reality.

Through his thesis work, Stapp became one of the first physicists to appreciate what has now become known as Bell’s Theorem. John Bell worked at CERN, the sprawling physics lab outside Geneva, Switzerland, designing particle accelerators. He was not paid to do theoretical physics. Yet the soft-spoken, red-bearded Irishman produced what Stapp would, years later, call “the most profound discovery of science.” In a 1964 paper, Bell addressed a seeming paradox that had bedeviled physics since 1935. In that year, Albert Einstein and two younger colleagues, Boris Podolsky and Nathan Rosen, had published a paper that had grown out of Einstein’s decade-long debate with Niels Bohr about the meaning of the quantum theories that emerged in the 1920s and 1930s. Einstein was convinced that quantum theory was merely a statistical
description of a deeper reality that scientists should strive to uncover. He devised countless
thought experiments
(what would happen if…?) to persuade Bohr that quantum theory was inadequate. The paper he wrote with Podolsky and Rosen (the trio became known as EPR) in 1935 proposed one of the most famous thought experiments in modern physics.

“Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” is about a quality of physical reality called locality.
Locality
means that physical reality in one place cannot be influenced instantaneously by what someone chooses to do at the same time in some faraway place. The core of all classical notions of physical causation, locality holds that all physical effects are caused by local interactions among discrete material particles and their associated fields. Thus if two regions, each bounded in space and time, are separated by a distance so great that even light cannot travel from one to the other, then an action in one region cannot affect anything in the second.

The protagonist of the EPR paper (I am using the simplification offered by the American theoretical physicist David Bohm) is a single quantum particle called a pi meson. It decays into one electron and one positron, which speed off in opposite directions. Quantum mechanics, recall, holds that until an observer observes a property such as the location, momentum, or spin direction of a particle, that property remains undefined. But, as EPR noted, because the positron and electron originated in a single quantum state, their properties remain (according to quantum theory) forever correlated, in a curious and nonclassical state of affairs called
entanglement
. The reality of entanglement has been empirically validated numerous times, but its implications represent one of quantum mechanics’ deepest mysteries. Indeed, Schrödinger called entanglement the very essence, “the essential characteristic,” of quantum physics. Through entanglement, the spins of two entangled particles, for instance, are not independent. If the spin of the parent particle is, say, 3 up, then the spin of the daughter particles must be
something like 1 up and 2 up, or 5 up and 2 down—anything that adds up to the original particle’s spin. There is another way of looking at this. If you know the spin of the original particle, and you measure the spin of one of the daughter particles, then you can infer the spin of the other daughter particle. This is the simplest expression of entanglement.