What Is the Connection Between Mind and Brain?
When it comes to sensations, emotions, and the ultimate question of consciousness, science still can’t explain the connection between neural patterns and the mind. We can characterize many emotions according to the physiological reactions that accompany them—a blush or change in the electrical conductance of your skin, for example; and we’ve also made progress in understanding what is going on in your brain, both anatomically and chemically, as you experience those emotions. So we understand a lot about how the brain functions. What we understand very little about is the subjective experience of those emotions, the “felt quality” of experience, as philosopher David Chalmers calls it.
What does it mean to “feel bad,” or to experience a burn, or the color blue, or sexual desire?
In 1915 a scientist named Alfred Sturtevant carefully observed what we think of as stereotypical barroom behavior—a couple of males fighting over a female, charging each other, ending up in a chaotic tussle. What made his study noteworthy was that the vertices of this love triangle were fruit flies. Even simpler creatures like nematodes, many species of which are microscopic, also exhibit special behaviors related to mating. Nematodes procreate like crazy—grab a handful of soil humus, and the chances are you’ll have thousands of these prolific roundworms within your grasp. So forget trying to grasp the complexities of the human mind—what does sex “feel like” to a creature of the phylum Nematoda? It might seem silly to ask about feelings in a species so simple it can survive being frozen in liquid nitrogen. But for one nematode species, C. elegans, we have the complete blueprint of its construction—a map of all of its 959 cells, including the wiring of its 302-node neural network (you can find it online)—and there was the hope that the blueprint would help us to understand how sensations arise from its networks of neurons. Alas, even in a creature this simple, it did not.
What is the nature of inner experience, and how can it be the result of neural processes? How do neural processes create the mind? Chalmers termed that “the hard problem.” It’s so hard that philosophers and poets, theologians, scientists, and physicists have been wrestling with the question of the connection between the material and the immaterial worlds for millennia.
Plato, for example, viewed people as having an immortal soul inside a mortal body. Christianity embraced that idea, as did many other faiths, and some early scientists also embraced it. The great seventeenth-century physicist, mathematician, and philosopher René Descartes, like many before him, differentiated between physical substance and mental substance. In his view, the brain was a physical structure, a machine, but the mind—our thoughts and consciousness—was something altogether different, which did not operate according to the laws of physics. Today we call that idea “mind-body dualism.”
For Descartes, as for Deepak, it was philosophical considerations that seemed to drive him. In part Descartes was trying to refute “irreligious” people who put their faith solely in mathematics, and would not accept the immortality of the soul unless it could be mathematically and scientifically demonstrated. But Descartes was also grappling with the problem of how to account for physical phenomena in a way that was consistent with his underlying worldview. In this he differed from the Aristotelian tradition, which was the reigning philosophical belief at the time. The Aristotelian worldview holds, as Deepak does, that there is purpose in the universe. In Aristotle’s version of purpose, all objects in nature, both animate and inanimate, behave as they do for the sake of some end or goal, sometimes called a “final cause.” For example, a stone tossed into the air would be said to fall back to the Earth because it is striving to reach the Earth’s center. Unlike most scientists and scholars of his era, Descartes opposed this idea, and its apparent implication that stones can have knowledge of a goal, and of how to attain it. Instead, Descartes took a mechanistic approach, maintaining that nonhuman objects follow physical laws. His theory of mind-body dualism was in part an attempt to dissuade people from assigning mental properties to inanimate objects and nonhuman animals, and thereby to distinguish the human world, which he did see as being guided, ultimately, by mind and purpose, from the inanimate and nonhuman.
Descartes was aware of certain difficulties that plague mind-body dualism from the scientific viewpoint. For example, through what physical mechanism does the mind control the brain? An accomplished anatomist, Descartes eventually came to the conclusion that the interface between mind and brain was a physical structure called the pineal gland, tucked deep between the two hemispheres of the brain. As it is one of the only structures of the brain that does not exist in two mirror-image parts, one in the left hemisphere and one in the right, Descartes thought it was where mind and brain communicated, and he called it “the principal seat of the soul.”
Descartes’s anatomically grounded theory is not accepted today, even by those who believe in mind-body dualism. The “hard problem”—the question of where inner experience comes from—remains unsolved. But scientists feel no shame in not yet having arrived at the answers. They may come in the next century, or in the next millennium. Or if they are too complex for human understanding, they may never come. In any case, even on the basis of our limited knowledge today, it is difficult to maintain the distinction between an immaterial mind and a material brain. For one, if a realm that obeys physical laws were to interact with a realm that doesn’t, wouldn’t the interaction cause noticeable exceptions to the laws of nature in the physical realm? Today we can routinely measure physical phenomena, including those inside living human brains, to enormous degrees of accuracy, but we have seen no evidence of such exceptions. If they do exist, why don’t we see them? On the other hand, evidence that thoughts and even subjective feelings are manifestations of the physical state of connected neurons abounds.
For example, in the course of treating epilepsy patients, neurosurgeons sometimes implant tiny electrodes in their brains and stimulate the tissue with brief pulses of electrical current. What they observe goes far beyond the mechanical responses high school biology students used to observe when they applied electricity to make a frog’s leg twitch. Depending on where they place the electrode, the surgeons can cause patients to hear identifiable sounds, like a doorbell or the chirping of birds (when there are no such sounds in the vicinity); to suddenly recall an event from childhood; or to feel urges, such as the desire to move an arm or a leg. These feelings and experiences, which I think we would all agree occur in the “mind,” can be traced directly to the physical stimulation of the brain, persuasive evidence that the brain controls the experiences of mind, and not vice versa.
Even more dramatic evidence comes from patients with epilepsy so severe that to bring relief surgeons sever a nerve bundle called the corpus callosum. Such patients are called “split-brain” patients because severing the corpus callosum divides the brain into its two nearly mirror-image hemispheres, with nothing to connect them. Without the corpus callosum bridge between them, the left and right hemispheres can for the most part no longer communicate, coordinate, or integrate information. What does dividing the brain in two do to a patient’s mind? If the mind exists in an immaterial realm, the surgery should not affect it. But if the mind arises solely from the physical brain, splitting the brain should also split the mind.
Neuroscientist Christof Koch wrote about one such case, a split-brain patient who was asked how many seizures she had recently experienced. Her right hand went up, showing two fingers. Then her left hand, controlled by her brain’s opposite hemisphere, reached over and forced the fingers on her right hand down. After a pause, her right hand went back up and indicated three, but her left hand went up and indicated only one. The patient seemed to be of two minds, and they were having a spat. Eventually the patient complained verbally that her maverick left hand often “did things on its own.” Language, it turns out, is one of the few functions that resides on just one side of the brain, usually the left side, which controls the right hand. But though her right hemisphere could not speak, it could hear the remark. Apparently it didn’t like what it heard, because at that point a fight broke out between the two hands. If the mind were not reducible to the brain, there is no reason that splitting the brain into two should also split a single conscious mind into, as Koch wrote, “two conscious minds in one skull.”
Deepak writes, “It doesn’t matter if you track a brain cell back to the atoms that make it up, then farther back to subatomic particles.… No one can point to a specific physical process and say, ‘Aha, that’s where thinking comes from.’ ” Though it’s true that we still have a lot to learn about the connection between our neurons and our thoughts, not knowing “where thinking comes from” does not prove that the source of thought lies in an immaterial realm. Scientists don’t deny what seems special about human experience, but they try to avoid explanations of it that are contrary to the evidence. There are currently an estimated fifty thousand scientists worldwide studying the brain, and none of them, nor any of their predecessors, has ever found credible, replicable scientific evidence that people’s mental experiences are the result of anything other than physical processes that obey the same laws as every other assemblage of molecules.
That the origin of mind lies in the physical substance of the brain has been repeatedly demonstrated in biology, but it is also demanded by physics. It is of course obvious that if some immaterial entity from another realm knocks a lamp off a table, the laws of physics have been violated. You don’t need to study Newtonian mechanics to know that natural law doesn’t allow things to jump around without a physical cause. But the immaterial mind, as envisioned by Deepak, doesn’t go tossing lamps off tables. Deepak sees it as being a more subtle mover and shaker. And yet one of its chief activities is actually not subtle at all: the immaterial mind, according to Deepak, processes knowledge. In his view, it is this nonphysical mind that is the essence of who we are; it knows what we know, feels what we feel, and makes our judgments and decisions. But according to the laws of physics, the existence of knowledge, thoughts, feelings, or any other kind of information in an immaterial mind—that is, in a realm that has no physical substance—is an impossibility.
The kind of trouble one can run into if one allows for the existence of immaterial information is illustrated by a famous thought experiment conceived by physicist James Clerk Maxwell in 1867. Imagine, as we did in chapter 8, a box of gas with a partition down the middle. This time instead of a hole in the partition, imagine a tiny door in it—a door so small it can be opened and closed without expending an appreciable amount of energy. When the door is shut, the molecules on either side are in a constant state of motion, bouncing off the partition as well as off the walls of the box, but always remaining on the side of the box on which they started. Next, picture a creature, also of insignificant size and mass, standing at the door, observing the molecules and letting them pass one way or the other at his whim. As Maxwell imagined it, this creature has free will and intelligence, but negligible substance. In other words, it resides in an immaterial realm, just as Deepak believes our consciousness does. William Thomson, a contemporary of Maxwell’s, nicknamed it “Maxwell’s Demon.”
Suppose this Demon decides to let only fast-moving, high-energy molecules transit from left to right, and only slow-moving, low-energy molecules move from right to left. Since the temperature of the gas is a measure of the speed of its molecules, over time the gas on the right side of the box will become hot, and the gas on the left side, cool. In chapter 8, I explained why gas molecules in a box will never spontaneously gather on one side, but one can equally well say that they will never sort themselves into hot and cold. If such a scenario were really possible, it would be revolutionary. For example, you could use the temperature differential to drive an engine, which means you’d be able to power a vehicle without consuming any fuel. But that would violate the second law of thermodynamics, which dictates that the entropy—or disorder—of a closed system never decreases. The entropy of the gases in Maxwell’s box, however, is decreasing, as the Demon arranges them in such a well-ordered fashion.
This violation of the second law, which leaves the physicist wondering where the missing entropy could have gone, occurs because the Demon has been posited as having an immaterial mind. If, on the other hand, the Demon’s mind has a material basis, then the “closed system” I described would include not just the box of gas, but also the Demon’s mind. Let’s look at how that would change the entropy equation. In order for the Demon to do its work, it has to note and remember information about the velocity of the molecules. As that information accumulates in the Demon’s mind (or in a notebook, or in a computer’s memory if the Demon is a robot), the mind’s entropy increases. To understand why, compare an empty room to a room containing furniture. However you arrange the tables, chairs, and other odds and ends, the room will not be as orderly as when there is simply nothing in it. The tables and chairs are like the bits of information cluttering the Demon’s mind: as you add information, you increase entropy. The end result: the decrease in the entropy of the gas molecules in the box is offset by the increase in entropy caused by the information buildup in the Demon’s physical mind. With that, we understand where the missing entropy went, and we find that the second law has not been violated. (To those clever readers wondering why one can’t simply periodically erase the Demon’s memory, it turns out that all that does is transfer the entropy elsewhere through the erasing process!)
Physics defines not just knowledge of the kind the Demon possesses as information, but all our ideas, memories, thoughts, and feelings, which means, according to the laws of physics, that they must reside somewhere in the physical universe—whether embodied in the neural patterns in our brains, encoded in a computer circuit, or printed as letters on a page. Even our experiences of beauty, hope, love, and pain arise in a brain that obeys the ordinary laws of physics. Unfortunately, accepting that a mind that harbors information cannot exist in some immaterial realm does not mean that we understand the workings of consciousness. The challenges we face in trying to understand how a neural system that obeys the ordinary laws of physics can give rise to subjective experience make this one of the great scientific projects of our time. Although Deepak would probably call the attempt to locate the mind in the material world a reductionist’s pointless dream, many scientists are at work on just that project, complex and impossible as it may seem. And they are making real progress.
Koch wrote that when he started doing research on the question of consciousness in the late 1980s, it was practically considered a sign of cognitive decline—ill-advised as a career path for a young professor, and likely to make graduate students roll their eyes. But he and a few others did work on it, and today those attitudes have changed. There is a whole new science of consciousness. It is legitimate science, and it has helped us understand which structures in the brain produce emotions, sensations, and thoughts, and how they are chemically regulated and electrically connected. We still aren’t close to discovering the basis of “mind,” or consciousness, as an emergent phenomenon based on interactions among neurons. But every day more evidence emerges to support the idea that mental experiences like beauty, love, hope, and pain are produced by the physical brain. Researchers in Koch’s lab, for instance, have developed a way for subjects to activate individual nerve cells deep inside their own brains—concept cells like those I mentioned in chapter 1—enabling them to control the content of an image on an external computer screen by simply thinking about the image they want to see. Experiments like this one, and work that is being done in many other settings around the globe, encourage us to think we are on the right path, though we are far nearer to the beginning of the road than to the end of it.
Some years ago black colleges in America wanted to raise much-needed funds, and they came up with a brilliant ad campaign. Its slogan was “A mind is a terrible thing to waste.” It would be even more terrible to throw the mind away entirely. Leonard does that when he claims that love is understandable as essentially a brain process. This would be a bizarre statement in any case, although it seems somewhat more reasonable when the exact phrasing is pieced back together: “Beauty, hope, love, and pain arise in a brain that obeys the ordinary laws of physics.” Love and beauty are core experiences in spiritual life. We need to get to the bottom of where they come from. There is an answer, but to accept it, you have to see the difference between love and the products of a chemistry set.
Leonard calls for backup from fifty thousand brain researchers, and he presents their position fairly. In the field of neuroscience the mind is considered to be a by-product of the brain, the way sweat is a by-product of burning calories or flushed cheeks a by-product of sexual excitement. But thoughts are not readily broken down into data. Love and beauty aren’t reducible to data, either. As the eminent British physicist Russell Stannard writes, “There is no way we can see concepts like hope, fear, and pain being quantified.” In order to follow Christ’s injunction to seek the kingdom of heaven within, or the Greek ideal to know thyself, the road lies only through the mind. And so spirituality puts mind first, where it belongs.
So how did the brain manage to dethrone the mind? Twenty or thirty years ago the human brain was still poorly understood. One neurologist quipped that we knew so little about memory that the skull might as well be filled with sawdust. But the advent of new technologies shot brain research forward, and today a scan with an fMRI (functional magnetic resonance imaging) machine not only reveals the brain’s memory centers; it can show them lighting up in real time, or going dark if a patient is suffering from Alzheimer’s disease. Hope, pain, and fear may not be quantifiable, but at least we can film images of them as brain activity.
The logic that places brain before mind is amazingly weak, however. Let me give an analogy: I’m sure you would agree that you can’t play “Twinkle, Twinkle, Little Star” on a piano without a piano. That’s obvious, just as obvious as the fact that you can’t have a thought without a brain. But if somebody told you that the piano composed “Twinkle, Twinkle, Little Star,” the statement would make no sense. A piano is only a machine; it doesn’t create new music. You can’t overturn this fact by examining the molecules inside each ivory key under an electron microscope to explain where Mozart comes from, but brain researchers do just that when they probe the molecular structure of neurons for the hidden origin of thoughts and feelings. Before a piano can produce music, a mind must write the notes. Before a brain can register a thought, a mind must think it.
For centuries the mystery of how the mind relates to the body has been a philosophical question, not a practical one. So far as ordinary life goes, brain versus mind isn’t a pressing debate. We say, “I’ve made up my mind,” not “I’ve made up my brain.” The average person goes through life never questioning that it takes a mind to be human. But this seemingly ivory-tower issue has incredibly practical implications. You cannot be indifferent to the question of mind versus brain if the mind serves as a portal to a deeper reality; if reaching that reality can transform your life, mind versus brain turns into the most urgent question of all.
We don’t lack for inner voyagers. Neuroscience has already shown that the brain scans of advanced Buddhist monks are very different from the norm. (Earlier I mentioned the finding that the monks’ brains operated at twice the frequency of normal brains in the gamma wave region.) The biggest discovery was that general activity in the prefrontal cortex was very intense—more intense, in fact, than ever observed before—a change that came about after years of meditation on compassion. As it happens, the prefrontal cortex is the brain’s center for compassion, among other higher functions. In this case, it would be inaccurate to say that the brain changed itself. First the monks had the intention to be compassionate; they meditated upon it for years, and their brains followed suit.
This is the opposite of what science expected. One much-publicized view among Western doctors has been that visionaries like Saint Teresa of Avila and Saint Bernadette, figures who have had mystical experiences, might have suffered from brain lesions, epilepsy, or some other malady that fooled them into thinking they were experiencing God. (Among confirmed atheists, the way to explain a holy vision comes down to a choice between hoax, delusion, and brain disease. The last is actually the most compassionate explanation.) Skeptics can argue all they want about how an unbalanced brain fools mental patients into believing in illusions. Some schizophrenics with grandiose delusions believe that they can make a locomotive stop by standing in front of it and willing it to stop. Faith healers believe that they can cure cancer by asking God’s help. Scoffers call such beliefs magical thinking. Everyone knows that you can’t move objects with your mind. Yet that is precisely what you do when you make a fist or throw a ball: not only does your mind move thousands of molecules in the brain, but your intention spreads throughout the nervous system, reaching the muscles and bones—every step of the way is mind over matter. As for equating saintliness with mental disease, such a judgment is insulting and foolish on the very face of it.
What does matter is a strong desire to be close to God. As we saw with Tibetan monks, intention translates itself into new brain functioning. Why is that so incredible? Nobody can explain why we have any thoughts, so it’s not that experiencing God is more mysterious than experiencing orange juice or the World Series. We can’t shift in a spiritual direction unless the brain shifts, too, and it’s our desire that alters the material landscape of the brain, not vice versa.
In many ways neurology is a red herring when deciding what a valid experience amounts to, since the visual cortex lights up when you actually see a horse and when you dream of one. An image is an image is an image, to paraphrase Gertrude Stein. Spirituality embraces a wider perspective. The cosmos didn’t have to wait billions of years before the human brain evolved. The cosmos was behaving mindfully long before that. Here’s eminent physicist Freeman Dyson: “It appears that mind, as manifested by the capacity to make choices, is to some extent inherent in every electron.”
So which came first, mind or brain? Science is used to solving hard problems, but this one, as Leonard notes, is considered the hard problem. I’d like to propose that pitting mind versus brain is a no-win proposition. The hard problem can be settled without either side losing. Why must we claim that mind creates matter—or vice versa—in the first place? Such a need disappears once we concede that there is no entry point in the last 13.7 billion years when matter suddenly learned to think and feel. When we stop futilely searching for that fictitious moment, a better answer appears: mind has always been here, if not eternally, then as long as gravity and the laws of Nature have been here.
In this alternate view, the cosmic mind surrounds us so completely that no matter what we do it won’t go away. It exists in our heart, liver, and gut cells as much as in our brain, providing intelligence, organizing power, creativity, and everything else. Even if you lose your mind through psychosis, drugs, or a catastrophic accident, the aspect of intelligence that keeps the body going will be intact (as we witness with patients in a coma). This neatly solves the chicken-or-the-egg riddle about which came first, mind or brain. “Coming first” isn’t valid or relevant in the quantum vacuum, which is outside space and time. If gravity and mathematics began there, it’s a small step to give mind the same status. After all, there’s no way to experience mathematics, gravity, or anything else without a mind.
I realize that this small step carries science where many don’t want it to go, into the realm of things that cannot be quantified. But science is already there. (A personal aside: I once discussed consciousness with a prominent physicist deeply versed in the hard problem. When I asked if he wanted to discuss the issue publicly, he shrank away. “You don’t understand. Consciousness is the skeleton in the closet. We don’t discuss it, and if I did, my professional reputation would be ruined.”) Rumi, the beloved Sufi mystic, understood that mind is everywhere when he said, “The whole universe exists inside you. Ask all from yourself.” Placing the mind center stage in the universe solves a vexing riddle wrapped inside the hard problem, as follows: When I see a sunset in my mind’s eye, its glowing orange splashing across a sapphire sky, where is that sunset? It’s not in my brain, because the brain has no light or pictures inside it. There is nothing in the brain but soft quivering tissue, pockets of water, and stygian darkness. Yet the sunset I envision has to be somewhere, and the best answer is mental space.
In mental space mind and matter move together as one. If I want to remember my mother’s face, I conjure it up instantly. It doesn’t matter how many thousands of neurons must be orchestrated, or what centers of the brain must light up, to turn memory into a visible image. Mind and matter are inseparable. As the instrument of consciousness, the human brain needed time to evolve. Once it evolved sufficiently, a thought and a neuron became connected as perfectly as a pianist and a piano—only in this case, the brain plays the music of life.
Leonard offered Maxwell’s Demon to defend the basic laws of physics. I have no difficulty with that, so long as “basic laws” include the quantum world from which all possibilities spring. Let me offer Deepak’s Demon to defend the mind. This demon is perched on the top of the Empire State Building peering down at the traffic. Cars heading along Fifth Avenue sometimes turn left and sometimes turn right. The demon knows that all the cars are obeying the laws of physics, as are the atoms inside the bodies of the drivers. He knows that a statistical prediction can be made about which car might turn left or right. Does that mean that the laws of probability tell us what each driver is doing? Not at all, because Deepak’s Demon realizes that each car represents a mind making a decision. Am I going to Macy’s or to the United Nations? One is left, the other is right. Without the mind deciding first, cars don’t turn.
So the hard problem can be solved, but it takes a broader vision to do it. Reductionism isn’t enough. When asked what the quantum world means for everyday life, physics generally shrugs and goes about its day-to-day business. This attitude has been summarized as “Shut up and calculate.” Physics is proud of its desire to remain aloof from metaphysics. But like it or not, we must bring the essence of existence center stage. Our minds cannot rest until we know what the mind is. Spirituality has always welcomed that quest; now it’s time for science to do so as well.